WorldWideScience

Sample records for sunlight season snowmelt

  1. Modeling snowmelt infiltration in seasonally frozen ground

    Science.gov (United States)

    Budhathoki, S.; Ireson, A. M.

    2017-12-01

    In cold regions, freezing and thawing of the soil govern soil hydraulic properties that shape the surface and subsurface hydrological processes. The partitioning of snowmelt into infiltration and runoff has also important implications for integrated water resource management and flood risk. However, there is an inadequate representation of the snowmelt infiltration into frozen soils in most land-surface and hydrological models, creating the need for improved models and methods. Here we apply, the Frozen Soil Infiltration Model, FroSIn, which is a novel algorithm for infiltration in frozen soils that can be implemented in physically based models of coupled flow and heat transport. In this study, we apply the model in a simple configuration to reproduce observations from field sites in the Canadian prairies, specifically St Denis and Brightwater Creek in Saskatchewan, Canada. We demonstrate the limitations of conventional approaches to simulate infiltration, which systematically over-predict runoff and under predict infiltration. The findings show that FroSIn enables models to predict more reasonable infiltration volumes in frozen soils, and also represent how infiltration-runoff partitioning is impacted by antecedent soil moisture.

  2. Spatiotemporal patterns of High Mountain Asia's snowmelt season identified with an automated snowmelt detection algorithm, 1987-2016

    Science.gov (United States)

    Smith, Taylor; Bookhagen, Bodo; Rheinwalt, Aljoscha

    2017-10-01

    High Mountain Asia (HMA) - encompassing the Tibetan Plateau and surrounding mountain ranges - is the primary water source for much of Asia, serving more than a billion downstream users. Many catchments receive the majority of their yearly water budget in the form of snow, which is poorly monitored by sparse in situ weather networks. Both the timing and volume of snowmelt play critical roles in downstream water provision, as many applications - such as agriculture, drinking-water generation, and hydropower - rely on consistent and predictable snowmelt runoff. Here, we examine passive microwave data across HMA with five sensors (SSMI, SSMIS, AMSR-E, AMSR2, and GPM) from 1987 to 2016 to track the timing of the snowmelt season - defined here as the time between maximum passive microwave signal separation and snow clearance. We validated our method against climate model surface temperatures, optical remote-sensing snow-cover data, and a manual control dataset (n = 2100, 3 variables at 25 locations over 28 years); our algorithm is generally accurate within 3-5 days. Using the algorithm-generated snowmelt dates, we examine the spatiotemporal patterns of the snowmelt season across HMA. The climatically short (29-year) time series, along with complex interannual snowfall variations, makes determining trends in snowmelt dates at a single point difficult. We instead identify trends in snowmelt timing by using hierarchical clustering of the passive microwave data to determine trends in self-similar regions. We make the following four key observations. (1) The end of the snowmelt season is trending almost universally earlier in HMA (negative trends). Changes in the end of the snowmelt season are generally between 2 and 8 days decade-1 over the 29-year study period (5-25 days total). The length of the snowmelt season is thus shrinking in many, though not all, regions of HMA. Some areas exhibit later peak signal separation (positive trends), but with generally smaller magnitudes

  3. Spatiotemporal patterns of High Mountain Asia's snowmelt season identified with an automated snowmelt detection algorithm, 1987–2016

    Directory of Open Access Journals (Sweden)

    T. Smith

    2017-10-01

    Full Text Available High Mountain Asia (HMA – encompassing the Tibetan Plateau and surrounding mountain ranges – is the primary water source for much of Asia, serving more than a billion downstream users. Many catchments receive the majority of their yearly water budget in the form of snow, which is poorly monitored by sparse in situ weather networks. Both the timing and volume of snowmelt play critical roles in downstream water provision, as many applications – such as agriculture, drinking-water generation, and hydropower – rely on consistent and predictable snowmelt runoff. Here, we examine passive microwave data across HMA with five sensors (SSMI, SSMIS, AMSR-E, AMSR2, and GPM from 1987 to 2016 to track the timing of the snowmelt season – defined here as the time between maximum passive microwave signal separation and snow clearance. We validated our method against climate model surface temperatures, optical remote-sensing snow-cover data, and a manual control dataset (n = 2100, 3 variables at 25 locations over 28 years; our algorithm is generally accurate within 3–5 days. Using the algorithm-generated snowmelt dates, we examine the spatiotemporal patterns of the snowmelt season across HMA. The climatically short (29-year time series, along with complex interannual snowfall variations, makes determining trends in snowmelt dates at a single point difficult. We instead identify trends in snowmelt timing by using hierarchical clustering of the passive microwave data to determine trends in self-similar regions. We make the following four key observations. (1 The end of the snowmelt season is trending almost universally earlier in HMA (negative trends. Changes in the end of the snowmelt season are generally between 2 and 8 days decade−1 over the 29-year study period (5–25 days total. The length of the snowmelt season is thus shrinking in many, though not all, regions of HMA. Some areas exhibit later peak signal separation (positive

  4. Spatial variability and trends of seasonal snowmelt processes over Antarctic sea ice observed by satellite scatterometers

    Science.gov (United States)

    Arndt, S.; Haas, C.

    2017-12-01

    Snow is one of the key drivers determining the seasonal energy and mass budgets of sea ice in the Southern Ocean. Here, we analyze radar backscatter time series from the European Remote Sensing Satellites (ERS)-1 and-2 scatterometers, from the Quick Scatterometer (QSCAT), and from the Advanced Scatterometer (ASCAT) in order to observe the regional and inter-annual variability of Antarctic snowmelt processes from 1992 to 2014. On perennial ice, seasonal backscatter changes show two different snowmelt stages: A weak backscatter rise indicating the initial warming and metamorphosis of the snowpack (pre-melt), followed by a rapid rise indicating the onset of internal snowmelt and thaw-freeze cycles (snowmelt). In contrast, similar seasonal backscatter cycles are absent on seasonal ice, preventing the periodic retrieval of spring/summer transitions. This may be due to the dominance of ice bottom melt over snowmelt, leading to flooding and ice disintegration before strong snowmelt sets in. Resulting snowmelt onset dates on perennial sea ice show the expected latitudinal gradient from early melt onsets (mid-November) in the northern Weddell Sea towards late (end-December) or even absent snowmelt conditions further south. This result is likely related to seasonal variations in solar shortwave radiation (absorption). In addition, observations with different microwave frequencies allow to detect changing snow properties at different depths. We show that short wavelengths of passive microwave observations indicate earlier pre-melt and snowmelt onset dates than longer wavelength scatterometer observations, in response to earlier warming of upper snow layers compared to lower snow layers. Similarly, pre-melt and snowmelt onset dates retrieved from Ku-Band radars were earlier by an average of 11 and 23 days, respectively, than those retrieved from C-Band. This time difference was used to correct melt onset dates retrieved from Ku-Band to compile a consistent time series from

  5. Snowmelt timing, phenology, and growing season length in conifer forests of Crater Lake National Park, USA

    Science.gov (United States)

    O'Leary, Donal S.; Kellermann, Jherime L.; Wayne, Chris

    2018-02-01

    Anthropogenic climate change is having significant impacts on montane and high-elevation areas globally. Warmer winter temperatures are driving reduced snowpack in the western USA with broad potential impacts on ecosystem dynamics of particular concern for protected areas. Vegetation phenology is a sensitive indicator of ecological response to climate change and is associated with snowmelt timing. Human monitoring of climate impacts can be resource prohibitive for land management agencies, whereas remotely sensed phenology observations are freely available at a range of spatiotemporal scales. Little work has been done in regions dominated by evergreen conifer cover, which represents many mountain regions at temperate latitudes. We used moderate resolution imaging spectroradiometer (MODIS) data to assess the influence of snowmelt timing and elevation on five phenology metrics (green up, maximum greenness, senescence, dormancy, and growing season length) within Crater Lake National Park, Oregon, USA from 2001 to 2012. Earlier annual mean snowmelt timing was significantly correlated with earlier onset of green up at the landscape scale. Snowmelt timing and elevation have significant explanatory power for phenology, though with high variability. Elevation has a moderate control on early season indicators such as snowmelt timing and green up and less on late-season variables such as senescence and growing season length. PCA results show that early season indicators and late season indicators vary independently. These results have important implications for ecosystem dynamics, management, and conservation, particularly of species such as whitebark pine ( Pinus albicaulis) in alpine and subalpine areas.

  6. The hierarchy of controls on snowmelt-runoff generation over seasonally-frozen hillslopes

    OpenAIRE

    Coles, Anna E.; Appels, Willemijn M.; McConkey, Brian G.; McDonnell, Jeffrey J.

    2016-01-01

    Understanding and modeling snowmelt-runoff generation in seasonally-frozen regions is a major challenge in hydrology. Partly, this is because the controls on hillslope-scale snowmelt-runoff generation are potentially extensive and their hierarchy is poorly understood. Understanding the relative importance of controls (e.g. topography, vegetation, land use, soil characteristics, and precipitation dynamics) on runoff response is necessary for model development, spatial extrapolation, and runoff...

  7. Surface energy balance of seasonal snow cover for snow-melt ...

    Indian Academy of Sciences (India)

    This study describes time series analysis of snow-melt, radiation data and energy balance for a seasonal snow cover at Dhundi field station of SASE, which lies in Pir Panjal range of the. N–W Himalaya, for a winter season from 13 January to 12 April 2005. The analysis shows that mean snow surface temperature remains ...

  8. Seasonal change in precipitation, snowpack, snowmelt, soil water and streamwater chemistry, northern Michigan

    Science.gov (United States)

    Stottlemyer, R.; Toczydlowski, D.

    1999-01-01

    We have studied weekly precipitation, snowpack, snowmelt, soil water and streamwater chemistry throughout winter for over a decade in a small (176 ha) northern Michigan watershed with high snowfall and vegetated by 60 to 80 year-old northern hardwoods. In this paper, we examine physical, chemical, and biological processes responsible for observed seasonal change in streamwater chemistry based upon intensive study during winter 1996-1997. The objective was to define the contributions made to winter and spring streamwater chemical concentration and flux by processes as snowmelt, over-winter forest floor and surface soil mineralization, immobilization, and exchange, and subsurface flowpath. The forest floor and soil were unfrozen beneath the snowpack which permitted most snowmelt to enter. Over-winter soil mineralization and other biological processes maintain shallow subsurface ion and dissolved organic carbon (DOC) reservoirs. Small, but steady, snowmelt throughout winter removed readily mobilized soil NO3- which resulted in high over-winter streamwater concentrations but little flux. Winter soil water levels and flowpaths were generally deep which increased soil water and streamwater base cation (C(B)), HCO3-, and Si concentrations. Spring snowmelt increased soil water levels and removal of ions and DOC from the biologically active forest floor and shallow soils. The snowpack solute content was a minor component in determining streamwater ion concentration or flux during and following peak snowmelt. Exchangeable ions, weakly adsorbed anions, and DOC in the forest floor and surface soils dominated the chemical concentration and flux in soil water and streamwater. Following peak snowmelt, soil microbial immobilization and rapidly increased plant uptake of limiting nutrients removed nearly all available nitrogen from soil water and streamwater. During the growing season high evapotranspiration increased subsurface flowpath depth which in turn removed weathering

  9. Earlier Snowmelt Changes the Ratio Between Early and Late Season Forest Productivity

    Science.gov (United States)

    Knowles, J. F.; Molotch, N. P.; Trujillo, E.; Litvak, M. E.

    2017-12-01

    Future projections of declining snowpack and increasing potential evaporation associated with climate warming are predicted to advance the timing of snowmelt in mountain ecosystems globally. This scenario has direct implications for snowmelt-driven forest productivity, but the net effect of temporally shifting moisture dynamics is unknown with respect to the annual carbon balance. Accordingly, this study uses both satellite- and tower-based observations to document the forest productivity response to snowpack and potential evaporation variability between 1989 and 2012 throughout the southern Rocky Mountain ecoregion, USA. These results show that a combination of low snow accumulation and record high potential evaporation in 2012 resulted in the 34-year minimum ecosystem productivity that could be indicative of future conditions. Moreover, early and late season productivity were significantly and inversely related, suggesting that future shifts toward earlier or reduced snowmelt could increase late-season moisture stress to vegetation and thus restrict productivity despite a longer growing season. This relationship was further subject to modification by summer precipitation, and the controls on the early/late season productivity ratio are explored within the context of ecosystem carbon storage in the future. Any perturbation to the carbon cycle at this scale represents a potential feedback to climate change since snow-covered forests represent an important global carbon sink.

  10. Sunlight mediated seasonality in canopy structure and photosynthetic activity of Amazonian rainforests

    International Nuclear Information System (INIS)

    Bi, Jian; Knyazikhin, Yuri; Choi, Sungho; Park, Taejin; Barichivich, Jonathan; Ciais, Philippe; Fu, Rong; Ganguly, Sangram; Hall, Forrest; Hilker, Thomas; Huete, Alfredo; Jones, Matthew; Kimball, John; Lyapustin, Alexei I; Mõttus, Matti; Nemani, Ramakrishna R; Piao, Shilong; Poulter, Benjamin; Saleska, Scott R

    2015-01-01

    Resolving the debate surrounding the nature and controls of seasonal variation in the structure and metabolism of Amazonian rainforests is critical to understanding their response to climate change. In situ studies have observed higher photosynthetic and evapotranspiration rates, increased litterfall and leaf flushing during the Sunlight-rich dry season. Satellite data also indicated higher greenness level, a proven surrogate of photosynthetic carbon fixation, and leaf area during the dry season relative to the wet season. Some recent reports suggest that rainforests display no seasonal variations and the previous results were satellite measurement artefacts. Therefore, here we re-examine several years of data from three sensors on two satellites under a range of sun positions and satellite measurement geometries and document robust evidence for a seasonal cycle in structure and greenness of wet equatorial Amazonian rainforests. This seasonal cycle is concordant with independent observations of solar radiation. We attribute alternative conclusions to an incomplete study of the seasonal cycle, i.e. the dry season only, and to prognostications based on a biased radiative transfer model. Consequently, evidence of dry season greening in geometry corrected satellite data was ignored and the absence of evidence for seasonal variation in lidar data due to noisy and saturated signals was misinterpreted as evidence of the absence of changes during the dry season. Our results, grounded in the physics of radiative transfer, buttress previous reports of dry season increases in leaf flushing, litterfall, photosynthesis and evapotranspiration in well-hydrated Amazonian rainforests. (letter)

  11. Seasonal patterns in soil N availability in the arctic tundra in response to accelerated snowmelt and warming

    Science.gov (United States)

    Darrouzet-Nardi, A.; Wallenstein, M. D.; Steltzer, H.; Sullivan, P.; Melle, C.; Segal, A.; Weintraub, M. N.

    2010-12-01

    Arctic soils contain large stocks of carbon (C) and may act as a significant CO2 source in response to climate warming. However, nitrogen (N) availability limits both plant growth and decomposition in many Arctic sites, and may thus be a key constraint on climate-carbon feedbacks. While current models of tundra ecosystems and their responses to climate change assume that N limits plant growth and C limits decomposition, there is strong evidence to the contrary showing that N can also limit decomposition. For example, the production of both new microbial biomass and enzymes that degrade organic matter appear to be limited by N during the summer. N availability is strongly seasonal: we have previously observed relatively high availability early in the growing season followed by a pronounced crash in tussock tundra soils. To investigate the drivers of N availability throughout the season, we used a field manipulation of tussock tundra growing season length (~4 days acceleration of snowmelt) and air temperature (open top chambers) and a laboratory soil N addition in both early and late season. Nutrient availability throughout the field season was measured at high temporal resolution (25 measurements from soil thaw through early plant senescence). Results from a laboratory experiment in which N was added to early season and late season soils suggests that soil respiration is in fact N limited at both times of the season, though this limitation is temperature dependent with effects most pronounced at 10°C. High-resolution measurements of nutrients in the soil solution and extractable N throughout the season showed that although a nutrient crash in N can be observed mid-season, N availability can still fluctuate later in the season. Finally, effects of the extended growing season and increased air temperature have so far had few effects on soil nutrient N dynamics throughout the summer growing season, suggesting either an insensitivity of N availability to these

  12. Observations and simulations of the seasonal evolution of snowpack cold content and its relation to snowmelt and the snowpack energy budget

    Science.gov (United States)

    Jennings, Keith S.; Kittel, Timothy G. F.; Molotch, Noah P.

    2018-05-01

    Cold content is a measure of a snowpack's energy deficit and is a linear function of snowpack mass and temperature. Positive energy fluxes into a snowpack must first satisfy the remaining energy deficit before snowmelt runoff begins, making cold content a key component of the snowpack energy budget. Nevertheless, uncertainty surrounds cold content development and its relationship to snowmelt, likely because of a lack of direct observations. This work clarifies the controls exerted by air temperature, precipitation, and negative energy fluxes on cold content development and quantifies the relationship between cold content and snowmelt timing and rate at daily to seasonal timescales. The analysis presented herein leverages a unique long-term snow pit record along with validated output from the SNOWPACK model forced with 23 water years (1991-2013) of quality controlled, infilled hourly meteorological data from an alpine and subalpine site in the Colorado Rocky Mountains. The results indicated that precipitation exerted the primary control on cold content development at our two sites with snowfall responsible for 84.4 and 73.0 % of simulated daily gains in the alpine and subalpine, respectively. A negative surface energy balance - primarily driven by sublimation and longwave radiation emission from the snowpack - during days without snowfall provided a secondary pathway for cold content development, and was responsible for the remaining 15.6 and 27.0 % of cold content additions. Non-zero cold content values were associated with reduced snowmelt rates and delayed snowmelt onset at daily to sub-seasonal timescales, while peak cold content magnitude had no significant relationship to seasonal snowmelt timing. These results suggest that the information provided by cold content observations and/or simulations is most relevant to snowmelt processes at shorter timescales, and may help water resource managers to better predict melt onset and rate.

  13. The effect of season and latitude on in vitro vitamin D formation by sunlight in South Africa.

    Science.gov (United States)

    Pettifor, J M; Moodley, G P; Hough, F S; Koch, H; Chen, T; Lu, Z; Holick, M F

    1996-10-01

    To assess the effect of season and latitude on the in vitro formation of previtamin D3 and vitamin D3 from 7-dehydrocholesterol (7-DHC) by sunlight in two cities in South Africa, Cape Town and Johannesburg. An in vitro study utilising vials containing 7-DHC, which were exposed to sunlight for a period of 1 hour between 8:00 and 17:00 on 1 day a month for a year. Previtamin D3 and vitamin D3 were separated from 7-DHC by high-performance liquid chromatography, and the amounts formed were calculated with the use of external standards. A marked seasonal variation in vitamin D3 production was noted in Cape Town, with very little being formed during the winter months of April through September. In Johannesburg, in vitro formation changed little throughout the year, and was similar to that found in Cape Town during the summer. During sunlit hours, vitamin D3 production was maximal at midday and small quantities were still being formed between 8:00 and 9:00, and between 16:00 and 17:00 during the summer. During winter in Cape Town, peak formation at midday was less than one-third of that in Johannesburg, and negligible amounts were formed before 10:00 and after 15:00. The previously documented seasonal variation in serum 25-hydroxyvitamin D recorded in patients in Johannesburg is probably a consequence of the increased clothing worn and the decreased time spent out of doors during winter, rather than decreased ultraviolet radiation reaching the earth. The limited in vitro formation of vitamin D3 during winter in Cape Town may have clinical implications insofar as the management of metabolic bone diseases like rickets and osteoporosis is concerned. Breast-fed infants resident in the area are likely to suffer from vitamin D deficiency rickets unless vitamin D supplements are provided, or the mothers are encouraged to take their children out of doors.

  14. Taking the pulse of snowmelt: in situ sensors reveal seasonal, event and diurnal patterns of nitrate and dissolved organic matter variability in an upland forest stream

    Science.gov (United States)

    Brian A. Pellerin; John Franco Saraceno; James B. Shanley; Stephen D. Sebestyen; George R. Aiken; Wilfred M. Wollheim; Brian A. Bergamaschi

    2012-01-01

    Highly resolved time series data are useful to accurately identify the timing, rate, and magnitude of solute transport in streams during hydrologically dynamic periods such as snowmelt. We used in situ optical sensors for nitrate (NO3-) and chromophoric dissolved organic matter fluorescence (FDOM) to measure surface water...

  15. Biological consequences of earlier snowmelt from desert dust deposition in alpine landscapes.

    Science.gov (United States)

    Steltzer, Heidi; Landry, Chris; Painter, Thomas H; Anderson, Justin; Ayres, Edward

    2009-07-14

    Dust deposition to mountain snow cover, which has increased since the late 19(th) century, accelerates the rate of snowmelt by increasing the solar radiation absorbed by the snowpack. Snowmelt occurs earlier, but is decoupled from seasonal warming. Climate warming advances the timing of snowmelt and early season phenological events (e.g., the onset of greening and flowering); however, earlier snowmelt without warmer temperatures may have a different effect on phenology. Here, we report the results of a set of snowmelt manipulations in which radiation-absorbing fabric and the addition and removal of dust from the surface of the snowpack advanced or delayed snowmelt in the alpine tundra. These changes in the timing of snowmelt were superimposed on a system where the timing of snowmelt varies with topography and has been affected by increased dust loading. At the community level, phenology exhibited a threshold response to the timing of snowmelt. Greening and flowering were delayed before seasonal warming, after which there was a linear relationship between the date of snowmelt and the timing of phenological events. Consequently, the effects of earlier snowmelt on phenology differed in relation to topography, which resulted in increasing synchronicity in phenology across the alpine landscape with increasingly earlier snowmelt. The consequences of earlier snowmelt from increased dust deposition differ from climate warming and include delayed phenology, leading to synchronized growth and flowering across the landscape and the opportunity for altered species interactions, landscape-scale gene flow via pollination, and nutrient cycling.

  16. Some attributes of snow occurrence and snowmelt/sublimation rates ...

    African Journals Online (AJOL)

    2017-04-02

    Apr 2, 2017 ... regions may be strongly influenced by seasonal fluctuations in ... accurate snow mapping and modelling of snowmelt/runoff are ... regional climate and hydrology, earth surface processes, and rural livelihoods .... from clouds.

  17. Degradation of emerging contaminants from water under natural sunlight: The effect of season, pH, humic acids and nitrate and identification of photodegradation by-products.

    Science.gov (United States)

    Koumaki, Elena; Mamais, Daniel; Noutsopoulos, Constantinos; Nika, Maria-Christina; Bletsou, Anna A; Thomaidis, Nikolaos S; Eftaxias, Alexander; Stratogianni, Georgia

    2015-11-01

    Both photodegradation and hydrolysis of non-steroidal anti-inflammatory drugs (NSAIDs) and endocrine disrupting chemicals (EDCs) were investigated in order to evaluate their photochemical fate in aquatic environment and to assess the effect of season and specific characteristics of water (pH, humic acids and nitrate concentration) on the removal of target EDCs and NSAIDs through photodegradation. An additional objective was the identification of the photodegradation by-products of specific NSAIDs and their dependence on irradiation time. Selected compounds' transformation was investigated under natural sunlight radiation while control experiments were conducted in the dark. As expected, most of compounds' degradation rate decreased with decreasing light intensity between two different experimental periods. Most of the tested compounds exhibited different rates of degradation during direct and indirect photolysis. The degradation rate of the selected compounds increased in the presence of NO3(-) and the photodegradation rate was higher for some compounds in alkaline than in acidic solution. The effect of humic acids' presence in the water depends on the absorbance spectrum of the compound and the produced photosensitizers. More specifically, humic acids act as inner filter toward most of the selected NSAIDs and as photosensitizers toward most of the EDCs. The results of the irradiation experiments in the presence of both humic acids and NO3(-), indicate that the direct photolysis is much more efficient than indirect photochemical processes. Finally, several degradation by-products of ketoprofen and diclofenac were identified in the samples, exposed to sunlight. The dependence of these by-products on radiation time is also demonstrated. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Snowmelt Runoff: A New Focus of Urban Nonpoint Source Pollution

    OpenAIRE

    Jiunian Guan; Baixing Yan; Hui Zhu; Yingying Xu

    2012-01-01

    Irregular precipitation associated with global climate change had been causing various problems in urban regions. Besides the runoff due to rainfall in summer, the snowmelt runoff in early spring could also play an important role in deteriorating the water quality of the receiving waters. Due to global climate change, the snowfall has increased gradually in individual regions, and snowstorms occur more frequently, which leads to an enhancement of snowmelt runoff flow during the melting season...

  19. Snowmelt runoff: a new focus of urban nonpoint source pollution.

    Science.gov (United States)

    Zhu, Hui; Xu, Yingying; Yan, Baixing; Guan, Jiunian

    2012-11-30

    Irregular precipitation associated with global climate change had been causing various problems in urban regions. Besides the runoff due to rainfall in summer, the snowmelt runoff in early spring could also play an important role in deteriorating the water quality of the receiving waters. Due to global climate change, the snowfall has increased gradually in individual regions, and snowstorms occur more frequently, which leads to an enhancement of snowmelt runoff flow during the melting seasons. What is more, rivers just awaking from freezing constitute a frail ecosystem, with poor self-purification capacity, however, the urban snowmelt runoff could carry diverse pollutants accumulated during the winter, such as coal and/or gas combustion products, snowmelting agents, automotive exhaust and so on, which seriously threaten the receiving water quality. Nevertheless, most of the research focused on the rainfall runoff in rainy seasons, and the study on snowmelt runoff is still a neglected field in many countries and regions. In conclusion, due to the considerable water quantity and the worrisome water quality, snowmelt runoff in urban regions with large impervious surface areas should be listed among the important targets in urban nonpoint source pollution management and control.

  20. Snowmelt Runoff: A New Focus of Urban Nonpoint Source Pollution

    Science.gov (United States)

    Zhu, Hui; Xu, Yingying; Yan, Baixing; Guan, Jiunian

    2012-01-01

    Irregular precipitation associated with global climate change had been causing various problems in urban regions. Besides the runoff due to rainfall in summer, the snowmelt runoff in early spring could also play an important role in deteriorating the water quality of the receiving waters. Due to global climate change, the snowfall has increased gradually in individual regions, and snowstorms occur more frequently, which leads to an enhancement of snowmelt runoff flow during the melting seasons. What is more, rivers just awaking from freezing cosntitute a frail ecosystem, with poor self-purification capacity, however, the urban snowmelt runoff could carry diverse pollutants accumulated during the winter, such as coal and/or gas combustion products, snowmelting agents, automotive exhaust and so on, which seriously threaten the receiving water quality. Nevertheless, most of the research focused on the rainfall runoff in rainy seasons, and the study on snowmelt runoff is still a neglected field in many countries and regions. In conclusion, due to the considerable water quantity and the worrisome water quality, snowmelt runoff in urban regions with large impervious surface areas should be listed among the important targets in urban nonpoint source pollution management and control. PMID:23202881

  1. Increased spring freezing vulnerability for alpine shrubs under early snowmelt.

    Science.gov (United States)

    Wheeler, J A; Hoch, G; Cortés, A J; Sedlacek, J; Wipf, S; Rixen, C

    2014-05-01

    Alpine dwarf shrub communities are phenologically linked with snowmelt timing, so early spring exposure may increase risk of freezing damage during early development, and consequently reduce seasonal growth. We examined whether environmental factors (duration of snow cover, elevation) influenced size and the vulnerability of shrubs to spring freezing along elevational gradients and snow microhabitats by modelling the past frequency of spring freezing events. We sampled biomass and measured the size of Salix herbacea, Vaccinium myrtillus, Vaccinium uliginosum and Loiseleuria procumbens in late spring. Leaves were exposed to freezing temperatures to determine the temperature at which 50% of specimens are killed for each species and sampling site. By linking site snowmelt and temperatures to long-term climate measurements, we extrapolated the frequency of spring freezing events at each elevation, snow microhabitat and per species over 37 years. Snowmelt timing was significantly driven by microhabitat effects, but was independent of elevation. Shrub growth was neither enhanced nor reduced by earlier snowmelt, but decreased with elevation. Freezing resistance was strongly species dependent, and did not differ along the elevation or snowmelt gradient. Microclimate extrapolation suggested that potentially lethal freezing events (in May and June) occurred for three of the four species examined. Freezing events never occurred on late snow beds, and increased in frequency with earlier snowmelt and higher elevation. Extrapolated freezing events showed a slight, non-significant increase over the 37-year record. We suggest that earlier snowmelt does not enhance growth in four dominant alpine shrubs, but increases the risk of lethal spring freezing exposure for less freezing-resistant species.

  2. Development and field testing of agricultural snowmelting agents made from recycled bio-waste materials

    International Nuclear Information System (INIS)

    Hirota, T.; Hasegawa, M.; Tanaka, H.; Suzuki, S.; Tadano, T.

    2008-01-01

    In snow-covering region of Japan, the promotion of snowmelting with application of agricultural snowmelting agents ('Yusetsuzai' in Japanese) has been widely carried out by farmers at the snowmelting season. When black colored materials with albedo-lowering effect are spread on snow surface, absorption of solar radiation by snow is increased, the snowmelting is promoted and snow thawing date becomes earlier. As a result, the growing season of crop plants is extended. Existing agricultural snowmelting agents have been mostly made from industrial waste materials or industrial processed products due to requirement for the low cost of the raw materials. These agents may contain harmful heavy metal elements and may lead to environmental pollution. To solve these problems, we developed the new agricultural snowmelting agents made from recycled bio-waste materials generated from the fields of agriculture and fishery. The developed snowmelting agents were made from shells of Patinopecten yessoensis, fowl droppings and processed wastes of fish and shellfish, etc. Especially, the shells of Patinopecten yessoensis has problems due to generation of a huge quantity in Hokkaido. Therefore, the recycling-use of these waste materials was strongly requested and expected. The developed snowmelting agents were possible to spread efficiently and safely on the snow-surface without wide scattering by controlling the particle size within the range larger than 100 microm and smaller than 1180 microm. Results obtained from the field experiment showed that the albedo was decreased from 0.70 for natural snow to 0.20 and the promotion of snowmelting for 11 days was recognized when 100 kg/10a of developed agent was spread. The promoting ability of the developed agent was equivalent to those of the existing commercial snowmelting agents. (author)

  3. Sunlight and Vitamin D

    Science.gov (United States)

    Wacker, Matthias; Holick, Michael F.

    2013-01-01

    Vitamin D is the sunshine vitamin that has been produced on this earth for more than 500 million years. During exposure to sunlight 7-dehydrocholesterol in the skin absorbs UV B radiation and is converted to previtamin D3 which in turn isomerizes into vitamin D3. Previtamin D3 and vitamin D3 also absorb UV B radiation and are converted into a variety of photoproducts some of which have unique biologic properties. Sun induced vitamin D synthesis is greatly influenced by season, time of day, latitude, altitude, air pollution, skin pigmentation, sunscreen use, passing through glass and plastic, and aging. Vitamin D is metabolized sequentially in the liver and kidneys into 25-hydroxyvitamin D which is a major circulating form and 1,25-dihydroxyvitamin D which is the biologically active form respectively. 1,25-dihydroxyvitamin D plays an important role in regulating calcium and phosphate metabolism for maintenance of metabolic functions and for skeletal health. Most cells and organs in the body have a vitamin D receptor and many cells and organs are able to produce 1,25-dihydroxyvitamin D. As a result 1,25-dihydroxyvitamin D influences a large number of biologic pathways which may help explain association studies relating vitamin D deficiency and living at higher latitudes with increased risk for many chronic diseases including autoimmune diseases, some cancers, cardiovascular disease, infectious disease, schizophrenia and type 2 diabetes. A three-part strategy of increasing food fortification programs with vitamin D, sensible sun exposure recommendations and encouraging ingestion of a vitamin D supplement when needed should be implemented to prevent global vitamin D deficiency and its negative health consequences. PMID:24494042

  4. Forage yield and nitrogen nutrition dynamics of warm-season native forage genotypes under two shading levels and in full sunlight

    OpenAIRE

    Barro,Raquel Santiago; Varella,Alexandre Costa; Lemaire,Gilles; Medeiros,Renato Borges de; Saibro,João Carlos de; Nabinger,Carlos; Bangel,Felipe Villamil; Carassai,Igor Justin

    2012-01-01

    The successful achievement of a highly productive understorey pasture in silvopastoral systems depends on the use of well-adapted forage genotypes, showing good agronomic performance and persistence under shading and grazing. In this study, the herbage dry matter yield (DMY) and nitrogen nutrition dynamics were determined in three native warm-season grasses (Paspalum regnellii, Paspalum dilatatum and Paspalum notatum) and a forage legume (Arachis pintoi) under two shading levels compared with...

  5. Photochemical effects of sunlight.

    Science.gov (United States)

    Daniels, F

    1972-07-01

    The importance of sunlight in bringing about not only photosynthesis in plants, but also other photochemical effects, is reviewed. More effort should be devoted to photochemical storage of the sun's energy without the living plant. There is no theoretical reason to believe that such reactions are impossible. Ground rules for searching for suitable solar photochemical reactions are given, and a few attempts are described, but nothing successful has yet been found. Future possibilities are suggested. Photogalvanic cells which convert sunlight into electricity deserve further research. Eugene Rabinowitch has been an active pioneer in these fields.

  6. Forage yield and nitrogen nutrition dynamics of warm-season native forage genotypes under two shading levels and in full sunlight

    Directory of Open Access Journals (Sweden)

    Raquel Santiago Barro

    2012-07-01

    Full Text Available The successful achievement of a highly productive understorey pasture in silvopastoral systems depends on the use of well-adapted forage genotypes, showing good agronomic performance and persistence under shading and grazing. In this study, the herbage dry matter yield (DMY and nitrogen nutrition dynamics were determined in three native warm-season grasses (Paspalum regnellii, Paspalum dilatatum and Paspalum notatum and a forage legume (Arachis pintoi under two shading levels compared with full sun. The experiment was conducted in the Campanha region, Bagé, state of Rio Grande do Sul, Brazil, during two evaluation cycles (2008/2009 and 2009/2010. Three shade cloth levels (0%, 50% and 80% of light restriction were applied to the forage genotypes in a split plot design, in which shading levels were the main plot and forage genotypes were the subplots, with three replications. P. regnellii showed the highest accumulated DMY (1500 and 1700 g m-2, respectively, for the first and second evaluation cycles at all shading levels and showed no DMY decreased under the heavy shade (80%. Average DMY over the four genotypes under the 50% shade level was higher or equal compared with full sun. Influence of rainfall was observed on the DMY performance of all genotypes: the positive effect of moderate shading (50% on P. dilatatum and P. notatum DMY was associated to a low soil water availability status. Increased shading level resulted in high nitrogen nutrition index values on grasses, in comparison with full sun. All genotypes performed well under the moderate shading level, but the DMY of both P. regnellii and P. dilatatum and the herbage N content in P. notatum and A. pintoi of all genotypes stood out, showing that those main genotypes are promising to grow in silvopastoral systems at the Campanha region in southern Brazil.

  7. Deciduous trees are a large and overlooked sink for snowmelt water in the boreal forest

    Science.gov (United States)

    Young, Jessica; Bolton, W. Robert; Bhatt, Uma; Cristobal, Jordi; Thoman, Richard

    2016-01-01

    The terrestrial water cycle contains large uncertainties that impact our understanding of water budgets and climate dynamics. Water storage is a key uncertainty in the boreal water budget, with tree water storage often ignored. The goal of this study is to quantify tree water content during the snowmelt and growing season periods for Alaskan and western Canadian boreal forests. Deciduous trees reached saturation between snowmelt and leaf-out, taking up 21–25% of the available snowmelt water, while coniferous trees removed <1%. We found that deciduous trees removed 17.8–20.9 billion m3 of snowmelt water, which is equivalent to 8.7–10.2% of the Yukon River’s annual discharge. Deciduous trees transpired 2–12% (0.4–2.2 billion m3) of the absorbed snowmelt water immediately after leaf-out, increasing favorable conditions for atmospheric convection, and an additional 10–30% (2.0–5.2 billion m3) between leaf-out and mid-summer. By 2100, boreal deciduous tree area is expected to increase by 1–15%, potentially resulting in an additional 0.3–3 billion m3 of snowmelt water removed from the soil per year. This study is the first to show that deciduous tree water uptake of snowmelt water represents a large but overlooked aspect of the water balance in boreal watersheds.

  8. Hydrologic flow path development varies by aspect during spring snowmelt in complex subalpine terrain

    Science.gov (United States)

    Webb, Ryan W.; Fassnacht, Steven R.; Gooseff, Michael N.

    2018-01-01

    In many mountainous regions around the world, snow and soil moisture are key components of the hydrologic cycle. Preferential flow paths of snowmelt water through snow have been known to occur for years with few studies observing the effect on soil moisture. In this study, statistical analysis of the topographical and hydrological controls on the spatiotemporal variability of snow water equivalent (SWE) and soil moisture during snowmelt was undertaken at a subalpine forested setting with north, south, and flat aspects as a seasonally persistent snowpack melts. We investigated if evidence of preferential flow paths in snow can be observed and the effect on soil moisture through measurements of snow water equivalent and near-surface soil moisture, observing how SWE and near-surface soil moisture vary on hillslopes relative to the toes of hillslopes and flat areas. We then compared snowmelt infiltration beyond the near-surface soil between flat and sloping terrain during the entire snowmelt season using soil moisture sensor profiles. This study was conducted during varying snowmelt seasons representing above-normal, relatively normal, and below-normal snow seasons in northern Colorado. Evidence is presented of preferential meltwater flow paths at the snow-soil interface on the north-facing slope causing increases in SWE downslope and less infiltration into the soil at 20 cm depth; less association is observed in the near-surface soil moisture (top 7 cm). We present a conceptualization of the meltwater flow paths that develop based on slope aspect and soil properties. The resulting flow paths are shown to divert at least 4 % of snowmelt laterally, accumulating along the length of the slope, to increase the snow water equivalent by as much as 170 % at the base of a north-facing hillslope. Results from this study show that snow acts as an extension of the vadose zone during spring snowmelt and future hydrologic investigations will benefit from studying the snow and soil

  9. Psoriasis, Psoralen and Sunlight

    Directory of Open Access Journals (Sweden)

    R.P.C Naik

    1979-01-01

    Full Text Available Topical or oral administration of photoactive furocumarins followed by exposure to ultra violet light from artificial sources has been shown previously to clear psoriatic lesions. Sunlight has been chosen as the source of UVL m two separate paired comparison studies using topical and, oral 4,5, 8 trimethylpsoralen. Two out of 21 on topical therapy and none out of 6 patients on oral paired-comparison study showed faster clearance of the drug treated lesions compared to control sites.

  10. Responses of snowmelt runoff to climatic change in an inland river basin, Northwestern China, over the past 50 years

    Directory of Open Access Journals (Sweden)

    J. Wang

    2010-10-01

    Full Text Available The spatial and temporal variations of snowcover distribution, and snowmelt runoff are considered as sensitive indicators for climatic change. The purpose of this paper is to analyze and forecast the responses of snowmelt runoff to climate change in an inland river basin. The upper basin of Heihe River in Northwestern China was chose as the study area, and the observation data from the meteorological and hydrological stations were utilized to analyze the status and regularity of the climatic change over the past 50 years. Snow cover area was obtained by an optimized technology using Moderate Resolution Imaging Spectroradiometer data with Normalized Difference Snow Index adjustment and topographic correction. A concept of potential snowmelt was suggested to illustrate the response of spatial snowmelt to climate change. The results show that the annual SCA proportion and the potential snowmelt keep an increasing trend since 2000. There is a negative relationship between annual air temperature and SCA proportion from 2000 to 2008. Snowmelt Runoff Model was chose to simulate snowmelt runoff and scenario forecast the change trend of snowmelt runoff in this region. The results show that climatic warming was apparent in the upper basin of Heihe River over the past 50 a. Annual average air temperature of three different weather stations located in the basin has increased 2.1 °C, 2.6 °C and 2.9 °C respectively from 1956 to present. The snowmelt runoff has increased obviously from 1970 to present. With different warming climate scenarios, the results by using SRM simulating showed that the first occurred time of snowmelt runoff shift ahead and discharge become larger as responses of snowmelt runoff to air temperature increasing, and the influence of temperature rising on average discharge of the whole snow season is not obvious.

  11. Effects of snowmelt on watershed transit time distributions

    Science.gov (United States)

    Fang, Z.; Carroll, R. W. H.; Harman, C. J.; Wilusz, D. C.; Schumer, R.

    2017-12-01

    Snowmelt is the principal control of the timing and magnitude of water flow through alpine watersheds, but the streamflow generated may be displaced groundwater. To quantify this effect, we use a rank StorAge Selection (rSAS) model to estimate time-dependent travel time distributions (TTDs) for the East River Catchment (ERC, 84 km2) - a headwater basin of the Colorado River, and newly designated as the Lawrence Berkeley National Laboratory's Watershed Function Science Focus Area (SFA). Through the SFA, observational networks related to precipitation and stream fluxes have been established with a focus on environmental tracers and stable isotopes. The United Stated Geological Survey Precipitation Runoff Modeling System (PRMS) was used to estimate spatially- and temporally-variable boundary fluxes of effective precipitation (snowmelt & rain), evapotranspiration, and subsurface storage. The DiffeRential Evolution Adaptive Metropolis (DREAM) algorithm was used to calibrate the rSAS model to observed stream isotopic concentration data and quantify uncertainty. The sensitivity of the simulated TTDs to systematic changes in the boundary fluxes was explored. Different PRMS and rSAS model parameters setup were tested to explore how they affect the relationship between input precipitation, especially snowmelt, and the estimated TTDs. Wavelet Coherence Analysis (WCA) was applied to investigate the seasonality of TTD simulations. Our ultimate goal is insight into how the Colorado River headwater catchments store and route water, and how sensitive flow paths and transit times are to climatic changes.

  12. Snowmelt Pattern and Lake Ice Phenology around Tibetan Plateau Estimated from Enhanced Resolution Passive Microwave Data

    Science.gov (United States)

    Xiong, C.; Shi, J.; Wang, T.

    2017-12-01

    Snow and ice is very sensitive to the climate change. Rising air temperature will cause the snowmelt time change. In contrast, the change in snow state will have feedback on climate through snow albedo. The snow melt timing is also correlated with the associated runoff. Ice phenology describes the seasonal cycle of lake ice cover and includes freeze-up and breakup periods and ice cover duration, which is an important weather and climate indicator. It is also important for lake-atmosphere interactions and hydrological and ecological processes. The enhanced resolution (up to 3.125 km) passive microwave data is used to estimate the snowmelt pattern and lake ice phenology on and around Tibetan Plateau. The enhanced resolution makes the estimation of snowmelt and lake ice phenology in more spatial detail compared to previous 25 km gridded passive microwave data. New algorithm based on smooth filters and change point detection was developed to estimate the snowmelt and lake ice freeze-up and break-up timing. Spatial and temporal pattern of snowmelt and lake ice phonology are estimated. This study provides an objective evidence of climate change impact on the cryospheric system on Tibetan Plateau. The results show significant earlier snowmelt and lake ice break-up in some regions.

  13. Mercury and Dissolved Organic Matter Dynamics During Snowmelt in the Upper Provo River, Utah, USA

    Science.gov (United States)

    Packer, B. N.; Carling, G. T.; Nelson, S.; Aanderud, Z.; Shepherd Barkdull, N.; Gabor, R. S.

    2017-12-01

    Mercury (Hg) is deposited to mountains by atmospheric deposition and mobilized during snowmelt runoff, leading to Hg contamination in otherwise pristine watersheds. Mercury is typically transported with dissolved organic matter (DOM) from soils to streams and lakes. This study focused on Hg and DOM dynamics in the snowmelt-dominated upper Provo River watershed, northern Utah, USA. We sampled Hg, dissolved organic carbon (DOC) concentrations, and DOM fluorescence in river water, snowpack, and ephemeral streams over four years from 2014-2017 to investigate Hg transport mechanisms. During the snowmelt season (April through June), Hg concentrations typically increased from 1 to 8 ng/L showing a strong positive correlation with DOC. The dissolved Hg fraction was dominant in the river, averaging 75% of total Hg concentrations, suggesting that DOC is more important for transport than suspended particulate matter. Ephemeral channels, which represent shallow flow paths with strong interactions with soils, had the highest Hg (>10 ng/L) and DOC (>10 mg/L) concentrations, suggesting a soil water source of Hg and organic matter. Fluorescence spectroscopy results showed important changes in DOM type and quality during the snowmelt season and the soil water flow paths are activated. Changes in DOM characteristics during snowmelt improve the understanding of Hg dynamics with organic matter and elucidate transport pathways from the soil surface, ephemeral channels and groundwater to the Provo River. This study has implications for understanding Hg sources and transport mechanisms in mountain watersheds.

  14. Clouds and snowmelt on the north slope of Alaska

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, T.; Stamnes, K.; Bowling, S.A. [Univ. of Alaska, Fairbanks, AK (United States)

    1996-04-01

    Clouds have a large effect on the radiation field. Consequently, possible changes in cloud properties may have a very substantial impact on climate. Of all natural surfaces, seasonal snow cover has the highest surface albedo, which is one of the most important components of the climatic system. Interactions between clouds and seasonal snow cover are expected to have a significant effect on climate and its change at high latitudes. The purpose of this paper is to investigate the sensitivity of the surface cloud-radiative forcing during the period of snowmelt at high latitudes. The primary variables investigated are cloud liquid path (LWP) and droplet equivalent radius (r{sub e}). We will also examine the sensitivity of the surface radiative fluxes to cloud base height and cloud base temperature.

  15. Variability of Cloud Cover and Its Relation to Snowmelt and Runoff in the Mountainous Western United States

    Science.gov (United States)

    Sumargo, E.; Cayan, D. R.; Iacobellis, S.

    2014-12-01

    Obtaining accurate solar radiation input to snowmelt runoff models remains a fundamental challenge for water supply forecasters in the mountainous western U.S. The variability of cloud cover is a primary source of uncertainty in estimating surface radiation, especially given that ground-based radiometer networks in mountain terrains are sparse. Thus, remote sensed cloud properties provide a way to extend in situ observations and more importantly, to understand cloud variability in montane environment. We utilize 17 years of NASA/NOAA GOES visible albedo product with 4 km spatial and half-hour temporal resolutions to investigate daytime cloud variability in the western U.S. at elevations above 800 m. REOF/PC analysis finds that the 5 leading modes account for about two-thirds of the total daily cloud albedo variability during the whole year (ALL) and snowmelt season (AMJJ). The AMJJ PCs are significantly correlated with de-seasonalized snowmelt derived from CDWR CDEC and NRCS SNOTEL SWE data and USGS stream discharge across the western conterminous states. The sum of R2 from 7 days prior to the day of snowmelt/discharge amounts to as much as ~52% on snowmelt and ~44% on discharge variation. Spatially, the correlation patterns take on broad footprints, with strongest signals in regions of highest REOF weightings. That the response of snowmelt and streamflow to cloud variation is spread across several days indicates the cumulative effect of cloud variation on the energy budget in mountain catchments.

  16. Changes to Watershed Hydrology due to Changing Snowmelt Patterns, Michigan, US

    Science.gov (United States)

    Ford, C.; Kendall, A. D.; Hyndman, D. W.

    2017-12-01

    With increasing temperatures and changing precipitation patterns associated with global climate change, the future of hydrologic resources related to snowmelt is less certain than ever. Most existing snowmelt hydrology research focuses on mountainous regions such as the western United States, where snowpack is a primary reservoir of available freshwater. Less research has been done on snowmelt hydrology in non-mountainous, temperate middle to upper latitude regions such as the Midwestern US, where snowmelt is still an important contributor to water budgets (and critically summer water supplies). This study examines the changes to watershed hydrology due to changing snowmelt patterns in Michigan, which has a tension line between seasonally-persistent snowpacks in the north, and episodic snowpacks in the south. This transition varies in space and time, and is likely moving northward as a consequence of climate change. Changes to snow and winter weather were statistically determined from output of the NOAA's Snow Data Assimilation System (SNODAS) model along with historical weather data from the Global Historical Climatology Network. Stream data from the USGS, combined with in-house monitoring data from groundwater and soil moisture networks provide insight into the hydrologic changes. Snowmelt in years with warmer winter temperatures tend to end earlier in the year, resulting in earlier peak stream flows. These changes become more noticeable in the northern regions of the state, where snowfall amounts can be amongst the largest in the country. This study also examines the changing spatial transition zone between regions with snow lasting throughout the season and regions with a more episodic snow presence. In an area with some of the largest freshwater resources in the world, significant changes to streamflow and groundwater recharge could impact already stressed ecosystems and local water supplies.

  17. A Pulse of Mercury and Major Ions in Snowmelt Runoff from a Small Arctic Alaska Watershed.

    Science.gov (United States)

    Douglas, Thomas A; Sturm, Matthew; Blum, Joel D; Polashenski, Christopher; Stuefer, Svetlana; Hiemstra, Christopher; Steffen, Alexandra; Filhol, Simon; Prevost, Romain

    2017-10-03

    Atmospheric mercury (Hg) is deposited to Polar Regions during springtime atmospheric mercury depletion events (AMDEs) that require halogens and snow or ice surfaces. The fate of this Hg during and following snowmelt is largely unknown. We measured Hg, major ions, and stable water isotopes from the snowpack through the entire spring melt runoff period for two years. Our small (2.5 ha) watershed is near Barrow (now Utqiaġvik), Alaska. We measured discharge, made 10 000 snow depths, and collected over 100 samples of snow and meltwater for chemical analysis in 2008 and 2009 from the watershed snowpack and ephemeral stream channel. Results show an "ionic pulse" of mercury and major ions in runoff during both snowmelt seasons, but major ion and Hg runoff concentrations were roughly 50% higher in 2008 than in 2009. Though total discharge as a percent of total watershed snowpack water equivalent prior to the melt was similar in both years (36% in 2008 melt runoff and 34% in 2009), it is possible that record low precipitation in the summer of 2007 led to the higher major ion and Hg concentrations in 2008 melt runoff. Total dissolved Hg meltwater runoff of 14.3 (± 0.7) mg/ha in 2008 and 8.1 (± 0.4) mg/ha in 2009 is five to seven times higher than that reported from other arctic watersheds. We calculate 78% of snowpack Hg was exported with snowmelt runoff in 2008 and 41% in 2009. Our results suggest AMDE Hg complexed with Cl - or Br - may be less likely to be photochemically reduced and re-emitted to the atmosphere prior to snowmelt, and we estimate that roughly 25% of the Hg in snowmelt is attributable to AMDEs. Projected Arctic warming, with more open sea ice leads providing halogen sources that promote AMDEs, may provide enhanced Hg deposition, reduced Hg emission and, ultimately, an increase in snowpack and snowmelt runoff Hg concentrations.

  18. Comparison between snowmelt-runoff and rainfall-runoff nonpoint source pollution in a typical urban catchment in Beijing, China.

    Science.gov (United States)

    Chen, Lei; Zhi, Xiaosha; Shen, Zhenyao; Dai, Ying; Aini, Guzhanuer

    2018-01-01

    As a climate-driven event, nonpoint source (NPS) pollution is caused by rainfall- or snowmelt-runoff processes; however, few studies have compared the characteristics and mechanisms of these two kinds of NPS processes. In this study, three factors relating to urban NPS, including surface dust, snowmelt, and rainfall-runoff processes, were analyzed comprehensively by both field sampling and laboratory experiments. The seasonal variation and leaching characteristics of pollutants in surface dust were explored, and the runoff quality of snowmelt NPS and rainfall NPS were compared. The results indicated that dusts are the main sources of urban NPS and more pollutants are deposited in dust samples during winter and spring. However, pollutants in surface dust showed a low leaching ratio, which indicated most NPS pollutants would be carried as particulate forms. Compared to surface layer, underlying snow contained higher chemical oxygen demand, total suspended solids (TSS), Cu, Fe, Mn, and Pb concentrations, while the event mean concentration of most pollutants in snowmelt tended to be higher in roads. Moreover, the TSS and heavy metal content of snowmelt NPS was always higher than those of rainfall NPS, which indicated the importance of controlling snowmelt pollution for effective water quality management.

  19. Carotenoids content and sunlight susceptibility

    International Nuclear Information System (INIS)

    Oppezzo, Oscar J.; Costa, Cristina; Pizarro, Ramon A.

    2005-01-01

    Full text: An environmental pink pigmented bacterium was isolated and identified as Rhodococcus sp. Pigmentation mutants were obtained by chemical mutagenesis. Pigments present in the wild type strain (RMB90), in a pale yellow mutant (RMB91) and in two mutants exhibiting increased pigmentation (RMB92 and RMB93), were extracted with chloroform-methanol and analyzed by reverse phase HPLC. Survival of these strains after exposure to sunlight and ultraviolet radiation from artificial sources was studied under different physiological and irradiation conditions. The ability of RMB91 to survive sunlight exposure was reduced with respect to that of RMB90. Resistance was similar in both strains when bacteria grew in the presence of a carotenoid synthesis inhibitor, which had no effect on survival of RMB91. Reduced sunlight resistance in RMB91 was also observed during irradiations under N2. Using artificial radiation sources, non pigmented bacteria were less resistant to UVA, but not to UVB or UVC. Lethal effects of sunlight and UVA on RMB92 and RMB93 were increased with respect to the wild type strain. Carotenoids protect Rhodococcus sp against deleterious effects of sunlight. In non-photosynthetic bacteria studied to date, photo protection by carotenoids was dependent on [O 2 ]. This is not the case with Rhodococcus sp RMB90, suggesting the occurrence of a different mechanism for protection. UVA radiation seems to playa key role in photo-damage. (author)

  20. Methods for snowmelt forecasting in upland Britain

    Directory of Open Access Journals (Sweden)

    R. J. Moore

    1999-01-01

    Full Text Available Snow, whilst not a dominant feature of Britain's maritime climate, can exert a significant influence on major floods through its contribution as snowmelt. Flood warning systems which fail to take account of melting snow can prove highly misleading. Selected results of a study on methods for improved snowmelt forecasting using trail catchments in upland Britain are presented here. Melt models considered range from a temperature excess formulation, with the option to include wind and rain heating effects, to a full energy budget melt formulation. Storage of melt in the pack is controlled by a store with two outlets, allowing slow release of water followed by rapid release once a critical liquid water content is reached. For shallow snow packs, a partial cover curve determines the proportion of the catchment over which snow extends. The melt, storage and release mechanisms together constitute the PACK snowmelt module which provides inputs to the catchment model. Either a lumped or distributed catchment model can be used, configured to receive snowmelt inputs from elevation zones within the catchment; a PACK snowmelt module operates independently within each zone and its inputs are controlled by appropriate elevation lapse rates. Measurements of snow depth and/or water equivalent, from snow cores or a snow pillow, are assimilated to correct for a lack of direct snowfall measurements needed to maintain a water balance during snowfall. The updating scheme involves operating a PACK module at the measurement site (the 'point model' in parallel to PACK modules in the catchment model, with point model errors being transferred using a proportioning scheme to adjust the snowpack water contents of the catchment model. The results of the assessment of different model variants broadly favour the simpler model formulations. Hourly automatic monitoring of water equivalent using the snow pillow can help in updating the model but preferential melting from the

  1. Evaluation of snowmelt simulation in the Weather Research and Forecasting model

    Science.gov (United States)

    Jin, Jiming; Wen, Lijuan

    2012-05-01

    The objective of this study is to better understand and improve snowmelt simulations in the advanced Weather Research and Forecasting (WRF) model by coupling it with the Community Land Model (CLM) Version 3.5. Both WRF and CLM are developed by the National Center for Atmospheric Research. The automated Snow Telemetry (SNOTEL) station data over the Columbia River Basin in the northwestern United States are used to evaluate snowmelt simulations generated with the coupled WRF-CLM model. These SNOTEL data include snow water equivalent (SWE), precipitation, and temperature. The simulations cover the period of March through June 2002 and focus mostly on the snowmelt season. Initial results show that when compared to observations, WRF-CLM significantly improves the simulations of SWE, which is underestimated when the release version of WRF is coupled with the Noah and Rapid Update Cycle (RUC) land surface schemes, in which snow physics is oversimplified. Further analysis shows that more realistic snow surface energy allocation in CLM is an important process that results in improved snowmelt simulations when compared to that in Noah and RUC. Additional simulations with WRF-CLM at different horizontal spatial resolutions indicate that accurate description of topography is also vital to SWE simulations. WRF-CLM at 10 km resolution produces the most realistic SWE simulations when compared to those produced with coarser spatial resolutions in which SWE is remarkably underestimated. The coupled WRF-CLM provides an important tool for research and forecasts in weather, climate, and water resources at regional scales.

  2. Spatial and Temporal Variation in Primary Productivity (NDVI) of Coastal Alaskan Tundra: Decreased Vegetation Growth Following Earlier Snowmelt

    Science.gov (United States)

    Gamon, John A.; Huemmrich, K. Fred; Stone, Robert S.; Tweedie, Craig E.

    2015-01-01

    In the Arctic, earlier snowmelt and longer growing seasons due to warming have been hypothesized to increase vegetation productivity. Using the Normalized Difference Vegetation Index (NDVI) from both field and satellite measurements as an indicator of vegetation phenology and productivity, we monitored spatial and temporal patterns of vegetation growth for a coastal wet sedge tundra site near Barrow, Alaska over three growing seasons (2000-2002). Contrary to expectation, earlier snowmelt did not lead to increased productivity. Instead, productivity was associated primarily with precipitation and soil moisture, and secondarily with growing degree days, which, during this period, led to reduced growth in years with earlier snowmelt. Additional moisture effects on productivity and species distribution, operating over a longer time scale, were evident in spatial NDVI patterns associated with microtopography. Lower, wetter regions dominated by graminoids were more productive than higher, drier locations having a higher percentage of lichens and mosses, despite the earlier snowmelt at the more elevated sites. These results call into question the oft-stated hypothesis that earlier arctic growing seasons will lead to greater vegetation productivity. Rather, they agree with an emerging body of evidence from recent field studies indicating that early-season, local environmental conditions, notably moisture and temperature, are primary factors determining arctic vegetation productivity. For this coastal arctic site, early growing season conditions are strongly influenced by microtopography, hydrology, and regional sea ice dynamics, and may not be easily predicted from snowmelt date or seasonal average air temperatures alone. Our comparison of field to satellite NDVI also highlights the value of in-situ monitoring of actual vegetation responses using field optical sampling to obtain detailed information on surface conditions not possible from satellite observations alone.

  3. Trends and variability in streamflow and snowmelt runoff timing in the southern Tianshan Mountains

    Science.gov (United States)

    Shen, Yan-Jun; Shen, Yanjun; Fink, Manfred; Kralisch, Sven; Chen, Yaning; Brenning, Alexander

    2018-02-01

    Streamflow and snowmelt runoff timing of mountain rivers are susceptible to climate change. Trends and variability in streamflow and snowmelt runoff timing in four mountain basins in the southern Tianshan were analyzed in this study. Streamflow trends were detected by Mann-Kendall tests and changes in snowmelt runoff timing were analyzed based on the winter/spring snowmelt runoff center time (WSCT). Pearson's correlation coefficient was further calculated to analyze the relationships between climate variables, streamflow and WSCT. Annual streamflow increased significantly in past decades in the southern Tianshan, especially in spring and winter months. However, the relations between streamflow and temperature/precipitation depend on the different streamflow generation processes. Annual precipitation plays a vital role in controlling recharge in the Toxkon basin, while the Kaidu and Huangshuigou basins are governed by both precipitation and temperature. Seasonally, temperature has a strong effect on streamflow in autumn and winter, while summer streamflow appears more sensitive to changes in precipitation. However, temperature is the dominant factor for streamflow in the glacierized Kunmalik basin at annual and seasonal scales. An uptrend in streamflow begins in the 1990s at both annual and seasonal scales, which is generally consistent with temperature and precipitation fluctuations. Average WSCT dates in the Kaidu and Huangshuigou basins are earlier than in the Toxkon and Kunmalik basins, and shifted towards earlier dates since the mid-1980s in all the basins. It is plausible that WSCT dates are more sensitive to warmer temperature in spring period compared to precipitation, except for the Huangshuigou basin. Taken together, these findings are useful for applications in flood risk regulation, future hydropower projects and integrated water resources management.

  4. Snowmelt response to simulated warming across a large elevation gradient, southern Sierra Nevada, California

    Directory of Open Access Journals (Sweden)

    K. N. Musselman

    2017-12-01

    Full Text Available In a warmer climate, the fraction of annual meltwater produced at high melt rates in mountainous areas is projected to decline due to a contraction of the snow-cover season, causing melt to occur earlier and under lower energy conditions. How snowmelt rates, including extreme events relevant to flood risk, may respond to a range of warming over a mountain front is poorly known. We present a model sensitivity study of snowmelt response to warming across a 3600 m elevation gradient in the southern Sierra Nevada, USA. A snow model was run for three distinct years and verified against extensive ground observations. To simulate the impact of climate warming on meltwater production, measured meteorological conditions were modified by +1 to +6 °C. The total annual snow water volume exhibited linear reductions (−10 % °C−1 consistent with previous studies. However, the sensitivity of snowmelt rates to successive degrees of warming varied nonlinearly with elevation. Middle elevations and years with more snowfall were prone to the largest reductions in snowmelt rates, with lesser changes simulated at higher elevations. Importantly, simulated warming causes extreme daily snowmelt (99th percentiles to increase in spatial extent and intensity, and shift from spring to winter. The results offer insight into the sensitivity of mountain snow water resources and how the rate and timing of water availability may change in a warmer climate. The identification of future climate conditions that may increase extreme melt events is needed to address the climate resilience of regional flood control systems.

  5. Constraining snowmelt in a temperature-index model using simulated snow densities

    KAUST Repository

    Bormann, Kathryn J.; Evans, Jason P.; McCabe, Matthew

    2014-01-01

    Current snowmelt parameterisation schemes are largely untested in warmer maritime snowfields, where physical snow properties can differ substantially from the more common colder snow environments. Physical properties such as snow density influence the thermal properties of snow layers and are likely to be important for snowmelt rates. Existing methods for incorporating physical snow properties into temperature-index models (TIMs) require frequent snow density observations. These observations are often unavailable in less monitored snow environments. In this study, previous techniques for end-of-season snow density estimation (Bormann et al., 2013) were enhanced and used as a basis for generating daily snow density data from climate inputs. When evaluated against 2970 observations, the snow density model outperforms a regionalised density-time curve reducing biases from -0.027gcm-3 to -0.004gcm-3 (7%). The simulated daily densities were used at 13 sites in the warmer maritime snowfields of Australia to parameterise snowmelt estimation. With absolute snow water equivalent (SWE) errors between 100 and 136mm, the snow model performance was generally lower in the study region than that reported for colder snow environments, which may be attributed to high annual variability. Model performance was strongly dependent on both calibration and the adjustment for precipitation undercatch errors, which influenced model calibration parameters by 150-200%. Comparison of the density-based snowmelt algorithm against a typical temperature-index model revealed only minor differences between the two snowmelt schemes for estimation of SWE. However, when the model was evaluated against snow depths, the new scheme reduced errors by up to 50%, largely due to improved SWE to depth conversions. While this study demonstrates the use of simulated snow density in snowmelt parameterisation, the snow density model may also be of broad interest for snow depth to SWE conversion. Overall, the

  6. Constraining snowmelt in a temperature-index model using simulated snow densities

    KAUST Repository

    Bormann, Kathryn J.

    2014-09-01

    Current snowmelt parameterisation schemes are largely untested in warmer maritime snowfields, where physical snow properties can differ substantially from the more common colder snow environments. Physical properties such as snow density influence the thermal properties of snow layers and are likely to be important for snowmelt rates. Existing methods for incorporating physical snow properties into temperature-index models (TIMs) require frequent snow density observations. These observations are often unavailable in less monitored snow environments. In this study, previous techniques for end-of-season snow density estimation (Bormann et al., 2013) were enhanced and used as a basis for generating daily snow density data from climate inputs. When evaluated against 2970 observations, the snow density model outperforms a regionalised density-time curve reducing biases from -0.027gcm-3 to -0.004gcm-3 (7%). The simulated daily densities were used at 13 sites in the warmer maritime snowfields of Australia to parameterise snowmelt estimation. With absolute snow water equivalent (SWE) errors between 100 and 136mm, the snow model performance was generally lower in the study region than that reported for colder snow environments, which may be attributed to high annual variability. Model performance was strongly dependent on both calibration and the adjustment for precipitation undercatch errors, which influenced model calibration parameters by 150-200%. Comparison of the density-based snowmelt algorithm against a typical temperature-index model revealed only minor differences between the two snowmelt schemes for estimation of SWE. However, when the model was evaluated against snow depths, the new scheme reduced errors by up to 50%, largely due to improved SWE to depth conversions. While this study demonstrates the use of simulated snow density in snowmelt parameterisation, the snow density model may also be of broad interest for snow depth to SWE conversion. Overall, the

  7. Effects of concentrated sunlight on organic photovoltaics

    DEFF Research Database (Denmark)

    Tromholt, Thomas; Katz, Eugene A.; Hirsch, Baruch

    2010-01-01

    We report the effects of concentrated sunlight on key photovoltaic parameters and stability of organic photovoltaics (OPV). Sunlight collected and concentrated outdoors was focused into an optical fiber and delivered onto a 1 cm2 bulk-heterojunction cell. Sunlight concentration C was varied gradu...

  8. Investigating the early snowmelt of 2015 in the Cascade Mountains using new MODIS-based snowmelt timing maps

    Science.gov (United States)

    O'Leary, D., III; Hall, D. K.; Medler, M. J.; Flower, A.; Matthews, R.

    2017-12-01

    The spring of 2015 brought an alarmingly early snowmelt to the Cascade Mountains, impacting flora, fauna, watersheds, and wildfire activity. It is important that we understand these events because model-based projections suggest that snowmelt may arrive an average of 10-40 days earlier across the continental US by the year 2100. Available snow measurement methods including SNOTEL stations and stream gauges offer insights into point locations and individual watersheds, but lack the detail needed to assess snowmelt anomalies across the landscape. In this study we describe our new MODIS-based snowmelt timing maps (STMs), validate them with SNOTEL measurements, then use them to explore the spatial patterns of the 2015 snowmelt in the Cascades. We found that the Cascade Mountains experienced snowmelt 41 days earlier than the 2001-2015 average, with many areas melting >70 days early. Of concern to land managers, these events may be the `new normal' in the decades to come.

  9. Hydrologic modelling of the effect of snowmelt and temperature on a ...

    Indian Academy of Sciences (India)

    Theoretically, the snowmelt process should be influenced by temperature changes. ... the snowmelt-runoff using the snowfall-snowmelt routine in Soil and Water Assessment Tool (SWAT). .... infiltration, evapotranspiration, soil and snow.

  10. Characterizing snowmelt regime of the river swat - a case study

    International Nuclear Information System (INIS)

    Malik, M.A.

    2015-01-01

    Snowmelt generates 70 to 80% of runoff of Indus River and its tributaries. Forecasting snowmelt generated flow is important for water management, reservoir operation and channel diversion. River Swat being not direct contributor to the existing reservoirs remained out of focus for characterizing its snowmelt regime. Thirty years (1971-2000) data of upper Swat catchment above Kalam gauging station was acquired from WAPDA. Normal monthly values over the period and average monthly values of each year were determined for stream flow, precipitation and temperature together with average monthly values of weighted and maximum temperature. Snowmelt regime was ascertained from plot of normal values of flow, precipitation and temperature. Using temperature index approach, average monthly flow over the snowmelt months (April, May and June) in terms of mm depth over the catchment was regressed on all the temperature indices using exponential, power and third degree polynomial functions. Tmax was found the best index for snowmelt with R2 as 0.902 for the third degree polynomial function. Runoff coefficient (ROC) for the total precipitation was conceptualized and through iteration was found as T max 100. The optimized value of ROC was used to segregate rain induced and snowmelt induced runoff. The segregated snowmelt induced runoff was again regressed on Tmax using the same function which slightly improved R2 to 0.916. The model was tested for four years of data and forecasted flow was found reasonable in the context of simplicity of the approach. (author)

  11. Port Sunlight, essai architectural et social

    OpenAIRE

    Machet, Laurence

    2017-01-01

    The purpose of this article is to examine the city of Port Sunlight, its history, design and originality. Created by William Lever in 1888 in order to house his newly-built soap factory, Port Sunlight is part of the numerous “factory villages” built in the wake of the industrial revolution according to philanthropic and utilitarian principles. But this article intends to show that Port Sunlight differs from other factory towns. Its careful design, elaborate architecture and public facilities ...

  12. Characteristics of Eurasian snowmelt and its impacts on the land surface and surface climate

    Science.gov (United States)

    Ye, Kunhui; Lau, Ngar-Cheung

    2018-03-01

    The local hydrological and climatic impacts of Eurasian snowmelt are studied using advanced land surface and atmospheric data. It is found that intense melting of snow is located at mid-high latitudes in April and May. Snowmelt plays an important role in determining the seasonal cycles of surface runoff and soil moisture (SM). Specifically, melting is accompanied by sharp responses in surface runoff and surface SM while the impacts are delayed for deeper-layer of soil. This is particularly significant in the western sector of Eurasia. On interannual timescales, the responses of various surface parameters to snowmelt in the same month are rather significant. However, the persistence of surface SM anomalies is weak due to the strong soil evaporation anomalies and surplus of surface energy for evaporation. Strong impacts on the sensible heat flux, planetary boundary layer height and precipitation in the next month following the melting of snow are identified in west Russia and Siberia. Downward propagation of surface SM anomalies is observed and a positive evaporation-convection feedback is identified in west Russia. However, the subsequent impacts on the local convective precipitation in late spring-summer and its contribution to the total precipitation are seemingly weak. The atmospheric water vapor convergence has strong control over the total precipitation anomalies. Overall, snowmelt-produced SM anomalies are not found to significantly impact the late spring-summer local climate anomalies in Northern Eurasia. Therefore, the delayed remote-responses of atmospheric circulation and climate to the melting of Eurasian snow may be only possible near the melting period.

  13. Hydrologic modelling of the effect of snowmelt and temperature on a ...

    Indian Academy of Sciences (India)

    In this study, a distributed hydrologic model is used to explore the orographic effects on the snowmelt-runoff using the snowfall-snowmelt routine in Soil and Water Assessment Tool (SWAT). Three parameters, namely maximum snowmelt factor, minimum snowmelt factor, and snowpack temperature lag were analysed during ...

  14. Sunlight inactivation of Escherichia coli in waste stabilization microcosms in a sahelian region (Ouagadougou, Burkina Faso).

    Science.gov (United States)

    Maïga, Ynoussa; Denyigba, Kokou; Wethe, Joseph; Ouattara, Aboubakar Sidiki

    2009-02-09

    Experiments on sunlight inactivation of Escherichia coli were conducted from November 2006 to June 2007 in eight outdoors microcosms with different depths filled with maturation pond wastewater in order to determine pond depth influence on sunlight inactivation of E. coli. The long-term aim was to maximize sunlight inactivation of waterborne pathogens in waste stabilization ponds (WSPs) in sahelian regions where number of sunny days enable longer exposure of wastewater to sunlight. The inactivation was followed during daylight from 8.00 h to 17.00 h and during the night. Sunlight inactivation rates (K(S)), as a function of cumulative global solar radiation (insolation), were 16 and 24 times higher than the corresponding dark inactivation (K(D)) rates, respectively in cold and warm season. In warm season, E. coli was inactivated far more rapidly. Inactivation of E. coli follows the evolution of radiation during the day. In shallow depth microcosms, E. coli was inactivated far more rapidly than in high depth microcosms. The physical chemical parameters [pH, dissolved oxygen (DO)] of microcosms water were higher in shallow depth microcosms than in high depth microcosms suggesting a synergistic effect of sunlight and these parameters to damage E. coli. To increase the efficiency of the elimination of waterborne bacteria, the use of maturation ponds with intermediate depths (0.4m) would be advisable in view of the high temperatures and thus evaporation recorded in sahelian regions.

  15. Some attributes of snow occurrence and snowmelt/sublimation rates ...

    African Journals Online (AJOL)

    Some attributes of snow occurrence and snowmelt/sublimation rates in the Lesotho ... and trimmed MODIS SNOMAP image using the ArcGIS Spatial Analyst tool. ... and hydrology, earth surface processes, and rural livelihoods in the Lesotho ...

  16. Snowmelt Timing as a Determinant of Lake Inflow Mixing

    Science.gov (United States)

    Roberts, D. C.; Forrest, A. L.; Sahoo, G. B.; Hook, S. J.; Schladow, S. G.

    2018-02-01

    Snowmelt is a significant source of carbon, nutrient, and sediment loads to many mountain lakes. The mixing conditions of snowmelt inflows, which are heavily dependent on the interplay between snowmelt and lake thermal regime, dictate the fate of these loads within lakes and their ultimate impact on lake ecosystems. We use five decades of data from Lake Tahoe, a 600 year residence-time lake where snowmelt has little influence on lake temperature, to characterize the snowmelt mixing response to a range of climate conditions. Using stream discharge and lake profile data (1968-2017), we find that the proportion of annual snowmelt entering the lake prior to the onset of stratification increases as annual snowpack decreases, ranging from about 50% in heavy-snow years to close to 90% in warm, dry years. Accordingly, in 8 recent years (2010-2017) where hourly inflow buoyancy and discharge could be quantified, we find that decreased snowpack similarly increases the proportion of annual snowmelt entering the lake at weak to positive buoyancy. These responses are due to the stronger effect of winter precipitation conditions on streamflow timing and temperature than on lake stratification, and point toward increased nearshore and near-surface mixing of inflows in low-snowpack years. The response of inflow mixing conditions to snowpack is apparent when isolating temperature effects on snowpack. Snowpack levels are decreasing due to warming temperatures during winter precipitation. Thus, our findings suggest that climate change may lead to increased deposition of inflow loads in the ecologically dynamic littoral zone of high-residence time, snowmelt-fed lakes.

  17. Hydrologic scales, cloud variability, remote sensing, and models: Implications for forecasting snowmelt and streamflow

    Science.gov (United States)

    Simpson, James J.; Dettinger, M.D.; Gehrke, F.; McIntire, T.J.; Hufford, Gary L.

    2004-01-01

    Accurate prediction of available water supply from snowmelt is needed if the myriad of human, environmental, agricultural, and industrial demands for water are to be satisfied, especially given legislatively imposed conditions on its allocation. Robust retrievals of hydrologic basin model variables (e.g., insolation or areal extent of snow cover) provide several advantages over the current operational use of either point measurements or parameterizations to help to meet this requirement. Insolation can be provided at hourly time scales (or better if needed during rapid melt events associated with flooding) and at 1-km spatial resolution. These satellite-based retrievals incorporate the effects of highly variable (both in space and time) and unpredictable cloud cover on estimates of insolation. The insolation estimates are further adjusted for the effects of basin topography using a high-resolution digital elevation model prior to model input. Simulations of two Sierra Nevada rivers in the snowmelt seasons of 1998 and 1999 indicate that even the simplest improvements in modeled insolation can improve snowmelt simulations, with 10%-20% reductions in root-mean-square errors. Direct retrieval of the areal extent of snow cover may mitigate the need to rely entirely on internal calculations of this variable, a reliance that can yield large errors that are difficult to correct until long after the season is complete and that often leads to persistent underestimates or overestimates of the volumes of the water to operational reservoirs. Agencies responsible for accurately predicting available water resources from the melt of snowpack [e.g., both federal (the National Weather Service River Forecast Centers) and state (the California Department of Water Resources)] can benefit by incorporating concepts developed herein into their operational forecasting procedures. ?? 2004 American Meteorological Society.

  18. Quantifying effects of climate change on the snowmelt-dominated groundwater resources of northern New England

    Science.gov (United States)

    Dudley, Robert W.; Hodgkins, Glenn A.; Shanley, James B.; Mack, Thomas J.

    2010-01-01

    Recent U.S. Geological Survey (USGS) climate studies in New England have shown substantial evidence of hydrologic changes during the last 100 years, including trends toward earlier snowmelt runoff, decreasing occurrence of river ice, and decreasing winter snowpack. These studies are being expanded to include investigation of trends in groundwater levels and fluctuations. Groundwater is an important drinking-water source throughout northern New England (Maine, New Hampshire, and Vermont). The USGS is currently investigating whether or not groundwater recharge from snowmelt and precipitation exhibits historical trends. In addition to trend-testing, groundwater resources also will be analyzed by relating groundwater-level changes to the large year-to-year variability in weather conditions. Introduction The USGS has documented many seasonal climate-related changes in the northeastern United States that have occurred during the last 30 to 150 years. These changes include earlier snowmelt runoff in the late winter and early spring, decreasing duration of ice on rivers and lakes, decreasing ratio of snowfall to total precipitation, and denser and thinner late-winter snowpack. All of these changes are consistent with warming winter and spring air temperatures (Dudley and Hodgkins, 2002; Hodgkins and others, 2002; Huntington and others, 2004; Hodgkins and others, 2005; Hodgkins and Dudley, 2006a; Hodgkins and Dudley, 2006b). Climate-model projections for the Northeast indicate air-temperature warming, earlier snowmelt runoff, increases in annual evaporation, and decreased low streamflows (Hayhoe and others, 2007). The contribution and timing of spring snowmelt to groundwater recharge is particularly important to groundwater resources in the northeastern United States where aquifers typically consist of thin sediments overlying crystalline bedrock with relatively little storage capacity (Mack, 2009). Following spring recharge, groundwater slowly flows into streams throughout

  19. Observations and simulations of snowpack cold content and its relationship to snowmelt timing and rate

    Science.gov (United States)

    Jennings, K. S.; Molotch, N. P.

    2017-12-01

    Mountain snowpacks serve as a vital water resource for more than 1 billion people across the globe. Two key properties of snowmelt—rate and timing—are controlled by the snowpack energy budget where incoming positive fluxes are balanced by a decrease in the energy deficit of the snowpack and a change in the phase of water from solid to liquid. In this context, the energy deficit, or cold content, regulates snowmelt as runoff does not commence until the deficit approaches zero. There is significant uncertainty surrounding cold content despite its relevance to snowmelt processes, likely due to the inherent difficulties in its observation. Our work has clarified the previously unresolved meteorological and energy balance controls on cold content development in seasonal snowpacks by leveraging two unique datasets from the Niwot Ridge LTER in the Rocky Mountains of Colorado. The first is a long-term snow pit record of snowpack properties from an alpine and subalpine site within the LTER. These data were augmented with a 23-year simulation of the snowpack at both sites using a quality controlled, serially complete, hourly forcing dataset. The observations and simulations both indicated that cold content primarily developed through new snowfall, while a negative energy budget provided a secondary pathway for cold content development, mainly through longwave emission and sublimation. Cold content gains from snowfall outnumbered energy balance gains by 438% in the alpine and 166% in the subalpine. Increased spring precipitation and later peak cold content significantly delayed snowmelt onset and daily melt rates were reduced by 32.2% in the alpine and 36.1% in the subalpine when an energy deficit needed to be satisfied. Furthermore, preliminary climate change simulations indicated warmer air temperatures reduced cold content accumulation, which increased the amount of snow lost to melt throughout the winter as incoming positive fluxes had to overcome smaller energy

  20. Soil Biogeochemical and Microbial Feedbacks along a Snowmelt-Dominated Hillslope-to-Floodplain Transect in Colorado.

    Science.gov (United States)

    Sorensen, P.; Beller, H. R.; Bill, M.; Bouskill, N.; Brodie, E.; Chakraborty, R.; Conrad, M. E.; Karaoz, U.; Polussa, A.; Steltzer, H.; Wang, S.; Williams, K. H.; Wilmer, C.; Wu, Y.

    2017-12-01

    Nitrogen export from mountainous watersheds is a product of multiple interactions among hydrological processes and soil-microbial-plant feedbacks along the continuum from terrestrial to aquatic environments. In snow-dominated systems, like the East River Watershed (CO), seasonal processes such as snowmelt exert significant influence on the annual hydrologic cycle and may also link spatially distinct catchment subsystems, such as hillslope and adjoining riparian floodplains. Further, snowmelt is occurring earlier each year and this is predicted to result in a temporal asynchrony between historically coupled microbial nutrient release and plant nutrient demand in spring, with the potential to increase N export from the East River Watershed. Here we summarize biogeochemical data collected along a hillslope-to-riparian floodplain transect at the East River site. Starting in Fall 2016, we sampled soils at 3 depths and measured dissolved pools of soil nutrients (e.g., NH4+, NO3-, DOC, P), microbial biomass CN, and microbial community composition over a seasonal time course, through periods of snow accumulation, snowmelt, and plant senescence. Soil moisture content in the top 5 cm of floodplain soils was nearly 4X greater across sampling dates, coinciding with 2X greater microbial biomass C, larger extractable pools of NH4+, and smaller pools of NO3- in floodplain vs. hillslope soils. These results suggest that microbially mediated redox processes played an important role in N cycling along the transect. Hillslope vs. floodplain location also appeared to be a key factor that differentiated soil microbial communities (e.g., a more important factor than seasonality or soil depth or type). Snow accumulation and snowmelt exerted substantial influence on soil biogeochemistry. For example, microbial biomass accumulation increased about 2X beneath the winter snowpack. Snowmelt resulted in a precipitous crash in the microbial population, with 2.5X reductions in floodplain and 2X

  1. Snowmelt water drives higher soil erosion than rainfall water in a mid-high latitude upland watershed

    Science.gov (United States)

    Wu, Yuyang; Ouyang, Wei; Hao, Zengchao; Yang, Bowen; Wang, Li

    2018-01-01

    The impacts of precipitation and temperature on soil erosion are pronounced in mid-high latitude areas, which lead to seasonal variations in soil erosion. Determining the critical erosion periods and the reasons behind the increased erosion loads are essential for soil management decisions. Hence, integrated approaches combining experiments and modelling based on field investigations were applied to investigate watershed soil erosion characteristics and the dynamics of water movement through soils. Long-term and continuous data for surface runoff and soil erosion variation characteristics of uplands in a watershed were observed via five simulations by the Soil and Water Assessment Tool (SWAT). In addition, laboratory experiments were performed to quantify the actual soil infiltrabilities in snowmelt seasons (thawed treatment) and rainy seasons (non-frozen treatment). The results showed that over the course of a year, average surface runoff and soil erosion reached peak values of 31.38 mm and 1.46 t ha-1 a-1, respectively, in the month of April. They also ranked high in July and August, falling in the ranges of 23.73 mm to 24.91 mm and 0.55 t ha-1 a-1 to 0.59 t ha-1 a-1, respectively. With the infiltration time extended, thawed soils showed lower infiltrabilities than non-frozen soils, and the differences in soil infiltration amounts between these two were considerable. These results highlighted that soil erosion was very closely and positively correlated with surface runoff. Soil loss was higher in snowmelt periods than in rainy periods due to the higher surface runoff in early spring, and the decreased soil infiltrability in snowmelt periods contributed much to this higher surface runoff. These findings are helpful for identification of critical soil erosion periods when making soil management before critical months, especially those before snowmelt periods.

  2. Assessing the ability of operational snow models to predict snowmelt runoff extremes (Invited)

    Science.gov (United States)

    Wood, A. W.; Restrepo, P. J.; Clark, M. P.

    2013-12-01

    In the western US, the snow accumulation and melt cycle of winter and spring plays a critical role in the region's water management strategies. Consequently, the ability to predict snowmelt runoff at time scales from days to seasons is a key input for decisions in reservoir management, whether for avoiding flood hazards or supporting environmental flows through the scheduling of releases in spring, or for allocating releases for multi-state water distribution in dry seasons of year (using reservoir systems to provide an invaluable buffer for many sectors against drought). Runoff forecasts thus have important benefits at both wet and dry extremes of the climatological spectrum. The importance of the prediction of the snow cycle motivates an assessment of the strengths and weaknesses of the US's central operational snow model, SNOW17, in contrast to process-modeling alternatives, as they relate to simulating observed snowmelt variability and extremes. To this end, we use a flexible modeling approach that enables an investigation of different choices in model structure, including model physics, parameterization and degree of spatiotemporal discretization. We draw from examples of recent extreme events in western US watersheds and an overall assessment of retrospective model performance to identify fruitful avenues for advancing the modeling basis for the operational prediction of snow-related runoff extremes.

  3. Hydrograph separation techniques in snowmelt-dominated watersheds

    Science.gov (United States)

    Miller, S.; Miller, S. N.

    2017-12-01

    This study integrates hydrological, geochemical, and isotopic data for a better understanding of different streamflow generation pathways and residence times in a snowmelt-dominated region. A nested watershed design with ten stream gauging sites recording sub-hourly stream stage has been deployed in a snowmelt-dominated region in southeastern Wyoming, heavily impacted by the recent bark beetle epidemic. LiDAR-derived digital elevation models help elucidate effects from topography and watershed metrics. At each stream gauging site, sub-hourly stream water conductivity and temperature data are also recorded. Hydrograph separation is a useful technique for determining different sources of runoff and how volumes from each source vary over time. Following previous methods, diurnal cycles from sub-hourly recorded streamflow and specific conductance data are analyzed and used to separate hydrographs into overland flow and baseflow components, respectively. A final component, vadose-zone flow, is assumed to be the remaining water from the total hydrograph. With access to snowmelt and precipitation data from nearby instruments, runoff coefficients are calculated for the different mechanisms, providing information on watershed response. Catchments are compared to understand how different watershed characteristics translate snowmelt or precipitation events into runoff. Portable autosamplers were deployed at two of the gauging sites for high-frequency analysis of stream water isotopic composition during peak flow to compare methods of hydrograph separation. Sampling rates of one or two hours can detect the diurnal streamflow cycle common during peak snowmelt. Prior research suggests the bark beetle epidemic has had little effect on annual streamflow patterns; however, several results show an earlier shift in the day of year in which peak annual streamflow is observed. The diurnal cycle is likely to comprise a larger percentage of daily streamflow during snowmelt in post

  4. Evaluating MODIS snow products for modelling snowmelt runoff: Case study of the Rio Grande headwaters

    Science.gov (United States)

    Steele, Caitriana; Dialesandro, John; James, Darren; Elias, Emile; Rango, Albert; Bleiweiss, Max

    2017-12-01

    Snow-covered area (SCA) is a key variable in the Snowmelt-Runoff Model (SRM) and in other models for simulating discharge from snowmelt. Landsat Thematic Mapper (TM), Enhanced Thematic Mapper (ETM +) or Operational Land Imager (OLI) provide remotely sensed data at an appropriate spatial resolution for mapping SCA in small headwater basins, but the temporal resolution of the data is low and may not always provide sufficient cloud-free dates. The coarser spatial resolution Moderate Resolution Imaging Spectroradiometer (MODIS) offers better temporal resolution and in cloudy years, MODIS data offer the best alternative for mapping snow cover when finer spatial resolution data are unavailable. However, MODIS' coarse spatial resolution (500 m) can obscure fine spatial patterning in snow cover and some MODIS products are not sensitive to end-of-season snow cover. In this study, we aimed to test MODIS snow products for use in simulating snowmelt runoff from smaller headwater basins by a) comparing maps of TM and MODIS-based SCA and b) determining how SRM streamflow simulations are changed by the different estimates of seasonal snow depletion. We compared gridded MODIS snow products (Collection 5 MOD10A1 fractional and binary SCA; SCA derived from Collection 6 MOD10A1 Normalised Difference Snow Index (NDSI) Snow Cover), and the MODIS Snow Covered-Area and Grain size retrieval (MODSCAG) canopy-corrected fractional SCA (SCAMG), with reference SCA maps (SCAREF) generated from binary classification of TM imagery. SCAMG showed strong agreement with SCAREF; excluding true negatives (where both methods agreed no snow was present) the median percent difference between SCAREF and SCAMG ranged between -2.4% and 4.7%. We simulated runoff for each of the four study years using SRM populated with and calibrated for snow depletion curves derived from SCAREF. We then substituted in each of the MODIS-derived depletion curves. With efficiency coefficients ranging between 0.73 and 0.93, SRM

  5. Research of Snow-Melt Process on a Heated Platform

    Directory of Open Access Journals (Sweden)

    Vasilyev Gregory P.

    2016-01-01

    Full Text Available The article has shown the results of experimental researches of the snow-melt on a heated platform-near building heat-pump snow-melt platform. The near-building (yard heat pump platforms for snow melt with the area up to 10-15 m2 are a basis of the new ideology of organization of the street cleaning of Moscow from snow in the winter period which supposes the creation in the megalopolis of the «distributed snow-melt system» (DSMS using non-traditional energy sources. The results of natural experimental researches are presented for the estimation of efficiency of application in the climatic conditions of Moscow of heat pumps in the snow-melt systems. The researches were conducted on a model sample of the near-building heat-pump platform which uses the low-potential thermal energy of atmospheric air. The conducted researches have confirmed experimentally in the natural conditions the possibility and efficiency of using of atmospheric air as a source of low-potential thermal energy for evaporation of the snow-melt heat pump systems in the climatic conditions of Moscow. The results of laboratory researches of snow-melt process on a heated horizontal platform are presented. The researches have revealed a considerable dependence of efficiency of the snow-melt process on its piling mode (form-building and the organization of the process of its piling mode (form-building and the organization of the process of its (snow mass heat exchange with the surface of the heated platform. In the process of researches the effect of formation of an «ice dome» under the melting snow mass called by the fact that in case of the thickness of snow loaded on the platform more than 10 cm the water formed from the melting snow while the contact with the heating surface don’t spread on it, but soaks into the snow, wets it due to capillary effect and freezes. The formation of «ice dome» leads to a sharp increase of snow-melt period and decreases the operating

  6. Water balance of goats in Jeneponto - South Sulawesi under sunlight exposure and water restriction

    Directory of Open Access Journals (Sweden)

    Djoni Prawira Rahardja

    2007-10-01

    Full Text Available Water balance of 5 does of Kacang goat of Jeneponto was studied under the condition of sunlight exposure and water restriction. The study was conducted in dry season with 4 consecutive treatments of 10 d with 4-5 d of adjustment period between two consecutive treatments: (1 indoor and unrestricted water; (2 indoor and restricted water; (3 10 h outdoor–and unrestricted water; (4 10 h outdoor – restricted water. The maximum air temperature of outdoor was 39.3OC, and it was 30OC in the indoor environment. In all treatments, the animals were placed in the individual crates. The plasma volume of the goats was higher under sunlight exposure, but it decreased by water restriction, while hematocrite value indicated a reverse responses. Sunlight exposure did not significantly decrease the intake and digestion of organic matter, but water restriction affected significantly and this effect was higher under sunlight exposre. The proportions of water loss through every avenue were maintained relatively constant either under water restriction or sunlight exposure in which the respration rate increased significantly. The findings suggest that sunlight exposure with unrestricted water resulted in a positive water balance without a significant change in organic matter intake and utilization. Water restriction resulted in a negative water balance, reducing organic matter intake and utilization. As the adaptive mechanisms, the goat appeared to be able to withstand in the harsh environment of Jeneponto by expanding plasma volume, increasing body temperature and respiration rate.

  7. Responses of Tree Seedlings near the Alpine Treeline to Delayed Snowmelt and Reduced Sky Exposure

    Directory of Open Access Journals (Sweden)

    Maaike Y. Bader

    2017-12-01

    Full Text Available Earlier snowmelt changes spring stress exposure and growing-season length, possibly causing shifts in plant species dominance. If such shifts involve trees, this may lead to changes in treeline position. We hypothesized that earlier snowmelt would negatively affect the performance of tree seedlings near the treeline due to higher spring stress levels, but less so if seedlings were protected from the main stress factors of night frosts and excess solar radiation. We exposed seedlings of five European treeline tree species: Larix decidua, Picea abies, Pinus cembra, Pinus uncinata, and Sorbus aucuparia to two snow-cover treatments (early and late melting, with about two weeks difference combined with reduced sky exposure during the day (shading or night (night warming, repeated in two years, at a site about 200 m below the regional treeline elevation. Physiological stress levels (as indicated by lower Fv/Fm in the first weeks after emergence from snow were higher in early-emerging seedlings. As expected, shade reduced stress, but contrary to expectation, night warming did not. However, early- and late-emerging seedlings did not differ overall in their growth or survival, and the interaction with shading was inconsistent between years. Overall, shading had the strongest effect, decreasing stress levels and mortality (in the early-emerging seedlings only, but also growth. A two-week difference in snow-cover duration did not strongly affect the seedlings, although even smaller differences have been shown to affect productivity in alpine and arctic tundra vegetation. Still, snowmelt timing cannot be discarded as important for regeneration in subalpine conditions, because (1 it is likely more critical in very snow-rich or snow-poor mountains or landscape positions; and (2 it can change (subalpine vegetation phenology and productivity, thereby affecting plant interactions, an aspect that should be considered in future studies.

  8. Stable water isotope variation in a Central Andean watershed dominated by glacier and snowmelt

    Directory of Open Access Journals (Sweden)

    N. Ohlanders

    2013-03-01

    Full Text Available Central Chile is an economically important region for which water supply is dependent on snow- and ice melt. Nevertheless, the relative contribution of water supplied by each of those two sources remains largely unknown. This study represents the first attempt to estimate the region's water balance using stable isotopes of water in streamflow and its sources. Isotopic ratios of both H and O were monitored during one year in a high-altitude basin with a moderate glacier cover (11.5%. We found that the steep altitude gradient of the studied catchment caused a corresponding gradient in snowpack isotopic composition and that this spatial variation had a profound effect on the temporal evolution of streamflow isotopic composition during snowmelt. Glacier melt and snowmelt contributions to streamflow in the studied basin were determined using a quantitative analysis of the isotopic composition of streamflow and its sources, resulting in a glacier melt contribution of 50–90% for the unusually dry melt year of 2011/2012. This suggests that in (La Niña years with little precipitation, glacier melt is an important water source for central Chile. Predicted decreases in glacier melt due to global warming may therefore have a negative long-term impact on water availability in the Central Andes. The pronounced seasonal pattern in streamflow isotope composition and its close relation to the variability in snow cover and discharge presents a potentially powerful tool to relate discharge variability in mountainous, melt-dominated catchments with related factors such as contributions of sources to streamflow and snowmelt transit times.

  9. Tracking snowmelt in the subsurface: time-lapse electrical resistivity imaging on an alpine hill slope.

    Science.gov (United States)

    Thayer, D.; Parsekian, A.; Hyde, K.; Beverly, D.; Speckman, H. N.; Ewers, B. E.

    2015-12-01

    In the mountain West region the winter snowpack provides more than 70% of our annual water supply. Modeling and predicting the timing and magnitude of snowmelt-driven water yield is difficult due to the complexities of hydrologic systems that move meltwater from snow to rivers. Particular challenges are understanding the temporal and spatial domain of subsurface hydraulic processes at relevant scales, which range from points to catchments. Subsurface characterization often requires borehole instrumentation, which is expensive and extremely difficult to install in remote, rugged terrain. Advancements in non-invasive geophysical methods allow us to monitor changes in geophysical parameters over time and infer changes in hydraulic processes. In the No-Name experimental catchment in the Medicine Bow National Forest in Wyoming, we are conducting a multi-season, time-lapse electrical resistivity imaging survey on a sub-alpine hill slope. This south-facing, partially forested slope ranges from 5 degrees to 35 degrees in steepness and consists of a soil mantle covering buried glacial talus deposits of unknown depth. A permanent grid of down-slope and cross-slope electrode arrays is monitored up to four times a day. The arrays span the entire vertical distance of the slope, from an exposed bedrock ridge to a seasonal drainage below, and cover treed and non-treed areas. Geophysical measurements are augmented by temperature and moisture time-series instrumented below the surface in a contiguous 3 meter borehole. A time-series of multiple resistivity models each day from May to July shows the changing distribution of subsurface moisture during a seasonal drying sequence punctuated by isolated rain events. Spatial patterns of changing moisture indicate that soil and gravel in the top two meters drain into a saturated layer parallel to the slope which overlies less saturated material. These results suggest that water from snowmelt and rain events tends to move down-slope beneath

  10. Ultra-accelerated natural sunlight exposure testing

    Science.gov (United States)

    Jorgensen, Gary J.; Bingham, Carl; Goggin, Rita; Lewandowski, Allan A.; Netter, Judy C.

    2000-06-13

    Process and apparatus for providing ultra accelerated natural sunlight exposure testing of samples under controlled weathering without introducing unrealistic failure mechanisms in exposed materials and without breaking reciprocity relationships between flux exposure levels and cumulative dose that includes multiple concurrent levels of temperature and relative humidity at high levels of natural sunlight comprising: a) concentrating solar flux uniformly; b) directing the controlled uniform sunlight onto sample materials in a chamber enclosing multiple concurrent levels of temperature and relative humidity to allow the sample materials to be subjected to accelerated irradiance exposure factors for a sufficient period of time in days to provide a corresponding time of about at least a years worth of representative weathering of the sample materials.

  11. Insignificant change in Antarctic snowmelt volume since 1979

    NARCIS (Netherlands)

    Kuipers Munneke, P.; Picard, G.; van den Broeke, M.R.; Lenaerts, J.T.M.; van Meijgaard, E.

    2012-01-01

    Surface snowmelt is widespread in coastal Antarctica. Satellite-based microwave sensors have been observing melt area and duration for over three decades. However, these observations do not reveal the total volume of meltwater produced on the ice sheet. Here we present an Antarctic melt volume

  12. Concentrated sunlight for organic solar cells

    DEFF Research Database (Denmark)

    Tromholt, Thomas

    2010-01-01

    . A high solar intensity study of inverted P3HT:PCBM solar cells is presented. Performance peak positions were found to be in the range of 1-5 suns, with smaller cells peaking at higher solar concentrations. Additionally, concentrated sunlight is demonstrated as a practical tool for accelerated stability...... were degraded resulting in acceleration factors in the range of 19-55. This shows that concentrated sunlight can be used as qualitatively to determine the lifetime of polymers under highly accelerated conditions....

  13. Snowmelt-induced subsurface and overland flows in a hillslope in Noname Watershed, Laramie River Basin, Wyoming

    Science.gov (United States)

    Rogers, T.; Ohara, N.

    2015-12-01

    Only few field observations have been implemented using surface and sub-surface trenches to investigate snowmelt-induced hillslope runoffs in mountainous regions. Hillslope trenches may be one of the most direct ways to measure subsurface and overland flow during winter and spring seasons. In July 2014, a 10 meter long trench was constructed with hand tools through glacial till on a south facing hillslope in the Noname Watershed, Medicine Bow National Forest, Wyoming, where heavy equipment and motorized vehicles were restricted. This trench measures subsurface and overland flow for a 610 square meters catchment which has an average slope of 25 degrees. This water-collecting trench is equipped with 4 soil-moisture and temperature sensors to detect the presence of unsaturated flow. Field observations from the trench showed that diurnal oscillation of snowmelt seemed to control the overland flow between the snow and soil surface. The water inputs to the hillslope, including rainfall, evaporation, and snowmelt rates, were estimated from the energy balance computations using the observed meteorological data at the site. Using the water input data, the lateral flow component through the deeper soil or weathered bedrock layer was also quantified by the mass balance in the catchment. This study provides one of key field activities for Wyoming Center for Environmental Hydrology and Geophysics (WyCEHG) project.

  14. Vitamin D, Sunlight and Prostate Cancer Risk

    Directory of Open Access Journals (Sweden)

    Krishna Vanaja Donkena

    2011-01-01

    Full Text Available Prostate cancer is the second common cancer in men worldwide. The prevention of prostate cancer remains a challenge to researchers and clinicians. Here, we review the relationship of vitamin D and sunlight to prostate cancer risk. Ultraviolet radiation of the sunlight is the main stimulator for vitamin D production in humans. Vitamin D's antiprostate cancer activities may be involved in the actions through the pathways mediated by vitamin D metabolites, vitamin D metabolizing enzymes, vitamin D receptor (VDR, and VDR-regulated genes. Although laboratory studies including the use of animal models have shown that vitamin D has antiprostate cancer properties, whether it can effectively prevent the development and/or progression of prostate cancer in humans remains to be inconclusive and an intensively studied subject. This review will provide up-to-date information regarding the recent outcomes of laboratory and epidemiology studies on the effects of vitamin D on prostate cancer prevention.

  15. Degadation of semiconducting polymers by concentrated sunlight

    DEFF Research Database (Denmark)

    Tromholt, Thomas; Manceau, Matthieu; Petersen, Martin Helgesen

    2011-01-01

    infra-red spectra of MEH-PPV degraded at 1 sun intensity and at high solar concentration only showed minor deviations in degradation mechanisms. The acceleration factor was found to vary linearly with the solar concentration. Finally, a comparison of the degradation rates at 1 sun and 100 suns...... was carried out in a materials study employing five different conjugated polymers relevant to polymer solar cells for which acceleration factors in the range 19–55 were obtained.......A lens based sunlight concentration setup was used to accelerate the degradation of semiconducting polymers. Sunlight was collected outdoor and focused into an optical fiber bundle allowing for indoor experimental work. Photo-degradation of several polymers was studied by UV–vis absorbance...

  16. Climate change adaptation in a highly urbanized snowmelt dominated basin in Central Chile

    Science.gov (United States)

    Vicuna, S.; Bustos, E.; Merino, P.; Henriquez Dole, L. E.; Jansen, S.; Gil, M.; Ocampo, A.; Poblete, D.; Tosoni, D.; Meza, F. J.; Donoso, G.; Melo, O.

    2015-12-01

    The Maipo river basin holds 40% of Chile's total population and produces almost half of the country's Gross Domestic Product. The basin is located in the semiarid and snowmelt dominated central region of the country and, aside from the typical pressures of growth in developing country basins, the Maipo river basin faces climate change impacts associated with a reduction in total runoff and changes in its seasonality. Surface water is the main water source for human settlements, natural ecosystems, and economic activities including agriculture, mining and hydropower production. In 2012 a research project, called MAPA (Maipo Plan de Adaptacion), began with the objective of articulating a climate variability and climate change adaptation plan for the Maipo river basin. The project engaged at the beginning a group of relevant water and land use stakeholders which allowed for a good representation of critical aspects of an adaptation plan such as the definition of objectives and performance indicators, future land use scenarios, modeling of the different components of the system and design of adaptation strategies. The presentation will highlight the main results of the research project with a special focus on the upper catchments of the basin. These results include the assessment of impacts associated with future climate and land use scenarios on key components of the hydrologic cycle including snowmelt and glacier contribution to runoff and subsequent impacts on water availability for the operation of hydropower facilities, satisfaction of instream (recreation and aquatic ecosystem) uses and provision of water for the city of Santiago (7 million people) and to irrigate more than 100,000 hectares of high value crops. The integrative approach followed in this project including different perspectives on the use of water in the basin provides a good opportunity to test the varying degree of impacts that could be associated with a given future scenario and also understand

  17. Influence of Slope-Scale Snowmelt on Catchment Response Simulated With the Alpine3D Model

    Science.gov (United States)

    Brauchli, Tristan; Trujillo, Ernesto; Huwald, Hendrik; Lehning, Michael

    2017-12-01

    Snow and hydrological modeling in alpine environments remains challenging because of the complexity of the processes affecting the mass and energy balance. This study examines the influence of snowmelt on the hydrological response of a high-alpine catchment of 43.2 km2 in the Swiss Alps during the water year 2014-2015. Based on recent advances in Alpine3D, we examine how snow distributions and liquid water transport within the snowpack influence runoff dynamics. By combining these results with multiscale observations (snow lysimeter, distributed snow depths, and streamflow), we demonstrate the added value of a more realistic snow distribution at the onset of melt season. At the site scale, snowpack runoff is well simulated when the mass balance errors are corrected (R2 = 0.95 versus R2 = 0.61). At the subbasin scale, a more heterogeneous snowpack leads to a more rapid runoff pulse originating in the shallower areas while an extended melting period (by a month) is caused by snowmelt from deeper areas. This is a marked improvement over results obtained using a traditional precipitation interpolation method. Hydrological response is also improved by the more realistic snowpack (NSE of 0.85 versus 0.74), even though calibration processes smoothen out the differences. The added value of a more complex liquid water transport scheme is obvious at the site scale but decreases at larger scales. Our results highlight not only the importance but also the difficulty of getting a realistic snowpack distribution even in a well-instrumented area and present a model validation from multiscale experimental data sets.

  18. Accuracy assessment of a net radiation and temperature index snowmelt model using ground observations of snow water equivalent in an alpine basin

    Science.gov (United States)

    Molotch, N. P.; Painter, T. H.; Bales, R. C.; Dozier, J.

    2003-04-01

    In this study, an accumulated net radiation / accumulated degree-day index snowmelt model was coupled with remotely sensed snow covered area (SCA) data to simulate snow cover depletion and reconstruct maximum snow water equivalent (SWE) in the 19.1-km2 Tokopah Basin of the Sierra Nevada, California. Simple net radiation snowmelt models are attractive for operational snowmelt runoff forecasts as they are computationally inexpensive and have low input requirements relative to physically based energy balance models. The objective of this research was to assess the accuracy of a simple net radiation snowmelt model in a topographically heterogeneous alpine environment. Previous applications of net radiation / temperature index snowmelt models have not been evaluated in alpine terrain with intensive field observations of SWE. Solar radiation data from two meteorological stations were distributed using the topographic radiation model TOPORAD. Relative humidity and temperature data were distributed based on the lapse rate calculated between three meteorological stations within the basin. Fractional SCA data from the Landsat Enhanced Thematic Mapper (5 acquisitions) and the Airborne Visible and Infrared Imaging Spectrometer (AVIRIS) (2 acquisitions) were used to derive daily SCA using a linear regression between acquisition dates. Grain size data from AVIRIS (4 acquisitions) were used to infer snow surface albedo and interpolated linearly with time to derive daily albedo values. Modeled daily snowmelt rates for each 30-m pixel were scaled by the SCA and integrated over the snowmelt season to obtain estimates of maximum SWE accumulation. Snow surveys consisting of an average of 335 depth measurements and 53 density measurements during April, May and June, 1997 were interpolated using a regression tree / co-krig model, with independent variables of average incoming solar radiation, elevation, slope and maximum upwind slope. The basin was clustered into 7 elevation / average

  19. A simple model for local scale sensible and latent heat advection contributions to snowmelt

    OpenAIRE

    Harder, Phillip; Pomeroy, John W.; Helgason, Warren D.

    2018-01-01

    Local-scale advection of energy from warm snow-free surfaces to cold snow-covered surfaces is an important component of the energy balance during snowcover depletion. Unfortunately, this process is difficult to quantify in one-dimensional snowmelt models. This manuscript proposes a simple sensible and latent heat advection model for snowmelt situations that can be readily coupled to one-dimensional energy balance snowmelt models. An existing advection parameterization was coupled to a concept...

  20. Holick's rule and vitamin D from sunlight.

    Science.gov (United States)

    Dowdy, John C; Sayre, Robert M; Holick, Michael F

    2010-07-01

    Holick's rule says that sun exposure 1/4 of a minimal erythemal dose (MED) over 1/4 of a body is equivalent to 1000 International Units (IU) oral vitamin D3. Webb and Engelsen recently commented that the ultraviolet (UV) spectrum used to establish Holick's rule is unknown. They consequently used a spring midday Boston solar spectrum to estimate ample sunlight exposures for previtamin D3 (preD3) at various locations. Literature review found the source upon which this rule is based was a fluorescent sunlamp (FS lamp). The FS spectrum is known and its relative weighting against the action spectra for erythema and the preD3 is significantly different from the solar spectrum used to derive the standard vitamin D effective dose (SDD). The preD3 effectiveness of the solar spectrum per unit erythemal hazard is greater than the FS lamp by a factor of 1.32. Consequently, UV exposure estimates based on Boston reference sunlight, instead of the UV lamp employed in the originating experiments, over estimate UV exposure equivalent to approximately 1000 IU orally by approximately 1/3. This redefinition of SDD impacts risk/benefit assessments of optimal/feasible sun exposure for vitamin D maintenance and the application of Holick's rule to rational public health messages. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

  1. Assimilation of snow cover and snow depth into a snow model to estimate snow water equivalent and snowmelt runoff in a Himalayan catchment

    Directory of Open Access Journals (Sweden)

    E. E. Stigter

    2017-07-01

    Full Text Available Snow is an important component of water storage in the Himalayas. Previous snowmelt studies in the Himalayas have predominantly relied on remotely sensed snow cover. However, snow cover data provide no direct information on the actual amount of water stored in a snowpack, i.e., the snow water equivalent (SWE. Therefore, in this study remotely sensed snow cover was combined with in situ observations and a modified version of the seNorge snow model to estimate (climate sensitivity of SWE and snowmelt runoff in the Langtang catchment in Nepal. Snow cover data from Landsat 8 and the MOD10A2 snow cover product were validated with in situ snow cover observations provided by surface temperature and snow depth measurements resulting in classification accuracies of 85.7 and 83.1 % respectively. Optimal model parameter values were obtained through data assimilation of MOD10A2 snow maps and snow depth measurements using an ensemble Kalman filter (EnKF. Independent validations of simulated snow depth and snow cover with observations show improvement after data assimilation compared to simulations without data assimilation. The approach of modeling snow depth in a Kalman filter framework allows for data-constrained estimation of snow depth rather than snow cover alone, and this has great potential for future studies in complex terrain, especially in the Himalayas. Climate sensitivity tests with the optimized snow model revealed that snowmelt runoff increases in winter and the early melt season (December to May and decreases during the late melt season (June to September as a result of the earlier onset of snowmelt due to increasing temperature. At high elevation a decrease in SWE due to higher air temperature is (partly compensated by an increase in precipitation, which emphasizes the need for accurate predictions on the changes in the spatial distribution of precipitation along with changes in temperature.

  2. A prediction and damage assessment model for snowmelt flood events in middle and high latitudes Region

    Science.gov (United States)

    Qiao, C.; Huang, Q.; Chen, T.; Zhang, X.

    2017-12-01

    In the context of global warming, the snowmelt flood events in the mountainous area of the middle and high latitudes are increasingly frequent and create severe casualties and property damages. Carrying out the prediction and risk assessment of the snowmelt flood is of great importance in the water resources management, the flood warning and prevention. Based on the remote sensing and GIS techniques, the relationships of the variables influencing the snowmelt flood such as the snow area, the snow depth, the air temperature, the precipitation, the land topography and land covers are analyzed and a prediction and damage assessment model for snowmelt floods is developed. This model analyzes and predicts the flood submerging area, flood depth, flood grade, and the damages of different underlying surfaces in the study area in a given time period based on the estimation of snowmelt amount, the snowmelt runoff, the direction and velocity of the flood. Then it was used to predict a snowmelt flood event in the Ertis River Basin in northern Xinjiang, China, during March and June, 2005 and to assess its damages including the damages of roads, transmission lines, settlements caused by the floods and the possible landslides using the hydrological and meteorological data, snow parameter data, DEM data and land use data. A comparison was made between the prediction results from this model and observation data including the flood measurement and its disaster loss data, which suggests that this model performs well in predicting the strength and impact area of snowmelt flood and its damage assessment. This model will be helpful for the prediction and damage assessment of snowmelt flood events in the mountainous area in the middle and high latitudes in spring, which has great social and economic significance because it provides a relatively reliable method for snowmelt flood prediction and reduces the possible damages caused by snowmelt floods.

  3. First passage Brownian functional properties of snowmelt dynamics

    Science.gov (United States)

    Dubey, Ashutosh; Bandyopadhyay, Malay

    2018-04-01

    In this paper, we model snow-melt dynamics in terms of a Brownian motion (BM) with purely time dependent drift and difusion and examine its first passage properties by suggesting and examining several Brownian functionals which characterize the lifetime and reactivity of such stochastic processes. We introduce several probability distribution functions (PDFs) associated with such time dependent BMs. For instance, for a BM with initial starting point x0, we derive analytical expressions for : (i) the PDF P(tf|x0) of the first passage time tf which specify the lifetime of such stochastic process, (ii) the PDF P(A|x0) of the area A till the first passage time and it provides us numerous valuable information about the total fresh water availability during melting, (iii) the PDF P(M) associated with the maximum size M of the BM process before the first passage time, and (iv) the joint PDF P(M; tm) of the maximum size M and its occurrence time tm before the first passage time. These P(M) and P(M; tm) are useful in determining the time of maximum fresh water availability and in calculating the total maximum amount of available fresh water. These PDFs are examined for the power law time dependent drift and diffusion which matches quite well with the available data of snowmelt dynamics.

  4. Life-threatening motor vehicle crashes in bright sunlight

    OpenAIRE

    Redelmeier, Donald A.; Raza, Sheharyar

    2017-01-01

    Abstract Bright sunlight may create visual illusions that lead to driver error, including fallible distance judgment from aerial perspective. We tested whether the risk of a life-threatening motor vehicle crash was increased when driving in bright sunlight. This longitudinal, case-only, paired-comparison analysis evaluated patients hospitalized because of a motor vehicle crash between January 1, 1995 and December 31, 2014. The relative risk of a crash associated with bright sunlight was estim...

  5. Traceable calibration of photovoltaic reference cells using natural sunlight

    Science.gov (United States)

    Müllejans, H.; Zaaiman, W.; Pavanello, D.; Dunlop, E. D.

    2018-02-01

    At the European Solar Test Installation (ESTI) photovoltaic (PV) reference cells are calibrated traceably to SI units via the World Radiometric Reference (WRR) using natural sunlight. The Direct Sunlight Method (DSM) is described in detail and the latest measurement results and an updated uncertainty budget are reported. These PV reference cells then provide a practical means for measuring the irradiance of natural or simulated sunlight during the calibration of other PV devices.

  6. High-Resolution Discharge Forecasting for Snowmelt and Rainfall Mixed Events

    Directory of Open Access Journals (Sweden)

    Tomasz Berezowski

    2018-01-01

    Full Text Available Discharge events induced by mixture of snowmelt and rainfall are strongly nonlinear due to consequences of rain-on-snow phenomena and snowmelt dependence on energy balance. However, they received relatively little attention, especially in high-resolution discharge forecasting. In this study, we use Random Forests models for 24 h discharge forecasting in 1 h resolution in a 105.9 km 2 urbanized catchment in NE Poland: Biala River. The forcing data are delivered by Weather Research and Forecasting (WRF model in 1 h temporal and 4 × 4 km spatial resolutions. The discharge forecasting models are set in two scenarios with snowmelt and rainfall and rainfall only predictors in order to highlight the effect of snowmelt on the results (both scenarios use also pre-forecast discharge based predictors. We show that inclusion of snowmelt decrease the forecast errors for longer forecasts’ lead times. Moreover, importance of discharge based predictors is higher in the rainfall only models then in the snowmelt and rainfall models. We conclude that the role of snowmelt for discharge forecasting in mixed snowmelt and rainfall environments is in accounting for nonlinear physical processes, such as initial wetting and rain on snow, which cannot be properly modelled by rainfall only.

  7. Remote sensing of drivers of spring snowmelt flooding in the North Central US

    Science.gov (United States)

    Spring snowmelt poses an annual flood risk in non-mountainous regions, such as the northern Great Plains of North America. However, ground observations are often not sufficient to characterize the spatiotemporal variation of drivers of snowmelt floods for operational flood forecasting purposes. Re...

  8. Improvement of distributed snowmelt energy balance modeling with MODIS-based NDSI-derived fractional snow-covered area data

    Science.gov (United States)

    Joel W. Homan; Charles H. Luce; James P. McNamara; Nancy F. Glenn

    2011-01-01

    Describing the spatial variability of heterogeneous snowpacks at a watershed or mountain-front scale is important for improvements in large-scale snowmelt modelling. Snowmelt depletion curves, which relate fractional decreases in snowcovered area (SCA) against normalized decreases in snow water equivalent (SWE), are a common approach to scale-up snowmelt models....

  9. Modeling a two-layer flow system at the subarctic, subalpine tree line during snowmelt

    Science.gov (United States)

    Leenders, Erica E.; Woo, Ming-Ko

    2002-10-01

    In the subarctic it is common to encounter a two-layer flow system consisting of a porous organic cover overlying frozen or unfrozen mineral soils with much lower hydraulic conductivities. The "simple lumped reservoir parametric," or "semidistributed land-use-based runoff processes" (SLURP), model was adapted to simulate runoff generated by such a flow system from an upland shrub land to an open woodland downslope. A subalpine site in Wolf Creek, Yukon, Canada, was subdivided into two aggregated simulation areas (ASA), each being a unit characterized by a set of parameters. The model computes the vertical water balance and flow generation from several storages, and then routes the water out of the ASA. When applied to the 1999 snowmelt season, the model simulated the very low lateral flow and a large increase in storage in the mineral soil, as was observed in the field. The model was used to assess the sensitivity of the two-layer flow system under a range of temperature, snow cover, and frost conditions. Results show that within the range of possible climatic conditions, the hydrologic system is unlikely to yield significant runoff across the subalpine tree line, but if ground ice is abundant in the soil pores, percolation will be limited and fast flow from the surface layer is enhanced.

  10. Snowmelt on the Greenland Ice Sheet as Derived From Passive Microwave Satellite Data

    Science.gov (United States)

    Abdalati, Waleed; Steffen, Konrad

    1997-01-01

    The melt extent of the snow on the Greenland ice sheet is of considerable importance to the ice sheet's mass and energy balance, as well as Arctic and global climates. By comparing passive microwave satellite data to field observations, variations in melt extent have been detected by establishing melt thresholds in the cross-polarized gradient ratio (XPGR). The XPGR, defined as the normalized difference between the 19-GHz horizontal channel and the 37-GHz vertical channel of the Special Sensor Microwave/Imager (SSM/I), exploits the different effects of snow wetness on different frequencies and polarizations and establishes a distinct melt signal. Using this XPGR melt signal, seasonal and interannual variations in snowmelt extent of the ice sheet are studied. The melt is found to be most extensive on the western side of the ice sheet and peaks in late July. Moreover, there is a notable increasing trend in melt area between the years 1979 and 1991 of 4.4% per year, which came to an abrupt halt in 1992 after the eruption of Mt. Pinatubo. A similar trend is observed in the temperatures at six coastal stations. The relationship between the warming trend and increasing melt trend between 1979 and 1991 suggests that a 1 C temperature rise corresponds to an increase in melt area of 73000 sq km, which in general exceeds one standard deviation of the natural melt area variability.

  11. Modification of Sunlight Radiation through Colored Photo-Selective Nets Affects Anthocyanin Profile in Vaccinium spp. Berries.

    Directory of Open Access Journals (Sweden)

    Laura Zoratti

    Full Text Available In recent years, the interest on the effects of the specific wavelengths of the light spectrum on growth and metabolism of plants has been increasing markedly. The present study covers the effect of modified sunlight conditions on the accumulation of anthocyanin pigments in two Vaccinium species: the European wild bilberry (V. myrtillus L. and the cultivated highbush blueberry (V. corymbosum L..The two Vaccinium species were grown in the same test field in the Alps of Trentino (Northern Italy under modified light environment. The modification of sunlight radiation was carried out in field, through the use of colored photo-selective nets throughout the berry ripening during two consecutive growing seasons. The anthocyanin profile was then assessed in berries at ripeness.The results indicated that the light responses of the two Vaccinium species studied were different. Although both studied species are shade-adapted plants, 90% shading of sunlight radiation was beneficial only for bilberry plants, which accumulated the highest content of anthocyanins in both seasons. The same condition, instead, was not favorable for blueberries, whose maturation was delayed for at least two weeks, and anthocyanin accumulation was significantly decreased compared to berries grown under sunlight conditions. Moreover, the growing season had strong influence on the anthocyanin accumulation in both species, in relation to temperature flow and sunlight spectra composition during the berry ripening period.Our results suggest that the use of colored photo-selective nets may be a complementary agricultural practice for cultivation of Vaccinium species. However, further studies are needed to analyze the effect of the light spectra modifications to other nutritional properties, and to elucidate the molecular mechanisms behind the detected differences between the two relative Vaccinium species.

  12. Modification of Sunlight Radiation through Colored Photo-Selective Nets Affects Anthocyanin Profile in Vaccinium spp. Berries.

    Science.gov (United States)

    Zoratti, Laura; Jaakola, Laura; Häggman, Hely; Giongo, Lara

    2015-01-01

    In recent years, the interest on the effects of the specific wavelengths of the light spectrum on growth and metabolism of plants has been increasing markedly. The present study covers the effect of modified sunlight conditions on the accumulation of anthocyanin pigments in two Vaccinium species: the European wild bilberry (V. myrtillus L.) and the cultivated highbush blueberry (V. corymbosum L.). The two Vaccinium species were grown in the same test field in the Alps of Trentino (Northern Italy) under modified light environment. The modification of sunlight radiation was carried out in field, through the use of colored photo-selective nets throughout the berry ripening during two consecutive growing seasons. The anthocyanin profile was then assessed in berries at ripeness. The results indicated that the light responses of the two Vaccinium species studied were different. Although both studied species are shade-adapted plants, 90% shading of sunlight radiation was beneficial only for bilberry plants, which accumulated the highest content of anthocyanins in both seasons. The same condition, instead, was not favorable for blueberries, whose maturation was delayed for at least two weeks, and anthocyanin accumulation was significantly decreased compared to berries grown under sunlight conditions. Moreover, the growing season had strong influence on the anthocyanin accumulation in both species, in relation to temperature flow and sunlight spectra composition during the berry ripening period. Our results suggest that the use of colored photo-selective nets may be a complementary agricultural practice for cultivation of Vaccinium species. However, further studies are needed to analyze the effect of the light spectra modifications to other nutritional properties, and to elucidate the molecular mechanisms behind the detected differences between the two relative Vaccinium species.

  13. Hydrology and snowmelt simulation of Snyderville Basin, Park City, and adjacent areas, Summit County, Utah

    Science.gov (United States)

    Brooks, Lynette E.; Mason, James L.; Susong, David D.

    1998-01-01

    Increasing residential and commercial development is placing increased demands on the ground- and surface-water resources of Snyderville Basin, Park City, and adjacent areas in the southwestern corner of Summit County, Utah. Data collected during 1993-95 were used to assess the quantity and quality of the water resources in the study area.Ground water within the study area is present in consolidated rocks and unconsolidated valley fill. The complex geology makes it difficult to determine the degree of hydraulic connection between different blocks of consolidated rocks. Increased ground-water withdrawal during 1983- 95 generally has not affected ground-water levels. Ground-water withdrawal in some areas, however, caused seasonal fluctuations and a decline in ground-water levels from 1994 to 1995, despite greater-than-normal recharge in the spring of 1995.Ground water generally has a dissolved-solids concentration that ranges from 200 to 600 mg/L. Higher sulfate concentrations in water from wells and springs near Park City and in McLeod Creek and East Canyon Creek than in other parts of the study area are the result of mixing with water that discharges from the Spiro Tunnel. The presence of chloride in water from wells and springs near Park City and in streams and wells near Interstate Highway 80 is probably caused by the dissolution of applied road salt. Chlorofluorocarbon analyses indicate that even though water levels rise within a few weeks of snowmelt, the water took 15 to 40 years to move from areas of recharge to areas of discharge.Water budgets for the entire study area and for six subbasins were developed to better understand the hydrologic system. Ground-water recharge from precipitation made up about 80 percent of the ground-water recharge in the study area. Ground-water discharge to streams made up about 40 percent of the surface water in the study area and ground-water discharge to springs and mine tunnels made up about 25 percent. Increasing use of

  14. Reversible degradation of inverted organic solar cells by concentrated sunlight

    DEFF Research Database (Denmark)

    Tromholt, Thomas; Manor, Assaf; Katz, Eugene A

    2011-01-01

    . The transient state is believed to be a result of the breakdown of the diode behaviour of the ZnO electron transport layer by O2 desorption, increasing the hole conductivity. These results imply that accelerated degradation of organic solar cells by concentrated sunlight is not a straightforward process......Concentrated sunlight was used to study the performance response of inverted P3HT:PCBM organic solar cells after exposure to high intensity sunlight. Correlations of efficiency as a function of solar intensity were established in the range of 0.5–15 suns at three different stages: for a pristine...

  15. Nature sunlight bleaching of Ti center ESR signal in quartz

    International Nuclear Information System (INIS)

    Yin Gongming; Liu Chunru; Li Jianping; Fang Jiahu; Gao Lu; Lin Min

    2009-01-01

    Quartz grains were extracted from granite. Bleaching was carried out in four different area chosen for their different altitudes (Beijing, Yinchuan, Germu, Lhasa), in order to observe their behavior under different intensities of the UV (Ultra violet) component of sunlight. The result of our experiments indicate that the Ti center signal is totally bleachable by the natural sunlight and show that the Ti center signal was reduced to zero after about 128 h in Beijing and after 56 h for Lhasa. We can speculate that different intensity of the UV component of sunlight lead to different minimal time necessary to obtain the total bleaching of the quartz sample. (authors)

  16. Effects of sub-Arctic shrub canopies on snowmelt energetics

    Science.gov (United States)

    Bewley, D.; Essery, R.; Pomeroy, J.

    2006-12-01

    Much of the low Arctic is covered with shrub tundra, and there is increasing evidence that snowmelt rates are substantially different between shrub tundra and poorly vegetated sites. The cause of this remains uncertain, however, and extends beyond simple differences in albedo. Results are presented in this study from a detailed field investigation at Wolf Creek Research Basin in 2004 to determine the effect of two different shrub canopy structures on both melt rates and the partitioning of melt energy. The low shrub site (LSS) was essentially an unvegetated snowfield prior to melt (mean albedo ~0.85), and shrubs only became exposed during the last few days of melt reaching a mean height of 0.31 m and mean Plant Area Index (PAI) of 0.32. Shrubs at the tall shrub site (TSS) were partially buried initially (shrub fraction, mean height and PAI of 0.2, 0.9 m and 0.41) but dominated the landscape by the end of melt (corresponding values of 0.71, 1.6 m and 0.6). Melt rates were higher at TSS up until the exposure of shrubs and bare ground at LSS, after which the rates converged. A Shrub-Snow Canopy Model (SSCM) is developed to improve snowmelt simulations for shrub canopies by parameterizing the key shrub effects on surface fluxes, including the extinction of shortwave irradiance beneath shrubs and in canopy gaps, and the enhancement of snow surface fluxes of longwave radiation and sensible heat. SSCM was run for LSS assuming no shrubs were present above the variable snow and bare ground tiles, whereas for TSS an increasing shrub fraction above each tile was prescribed from observations. Results from both sites suggest that sensible heat fluxes contributed more melt energy than net radiation, and were greater during early melt at TSS due to the warming of exposed shrubs. SWE was accurately predicted against transect measurements at TSS (rms error 4 mm), but was overestimated at LSS (rms error 13 mm) since both air temperatures and turbulent transport were underestimated

  17. Sunlight and Vitamin D: A global perspective for health.

    Science.gov (United States)

    Wacker, Matthias; Holick, Michael F

    2013-01-01

    Vitamin D is the sunshine vitamin that has been produced on this earth for more than 500 million years. During exposure to sunlight 7-dehydrocholesterol in the skin absorbs UV B radiation and is converted to previtamin D3 which in turn isomerizes into vitamin D3. Previtamin D3 and vitamin D3 also absorb UV B radiation and are converted into a variety of photoproducts some of which have unique biologic properties. Sun induced vitamin D synthesis is greatly influenced by season, time of day, latitude, altitude, air pollution, skin pigmentation, sunscreen use, passing through glass and plastic, and aging. Vitamin D is metabolized sequentially in the liver and kidneys into 25-hydroxyvitamin D which is a major circulating form and 1,25-dihydroxyvitamin D which is the biologically active form respectively. 1,25-dihydroxyvitamin D plays an important role in regulating calcium and phosphate metabolism for maintenance of metabolic functions and for skeletal health. Most cells and organs in the body have a vitamin D receptor and many cells and organs are able to produce 1,25-dihydroxyvitamin D. As a result 1,25-dihydroxyvitamin D influences a large number of biologic pathways which may help explain association studies relating vitamin D deficiency and living at higher latitudes with increased risk for many chronic diseases including autoimmune diseases, some cancers, cardiovascular disease, infectious disease, schizophrenia and type 2 diabetes. A three-part strategy of increasing food fortification programs with vitamin D, sensible sun exposure recommendations and encouraging ingestion of a vitamin D supplement when needed should be implemented to prevent global vitamin D deficiency and its negative health consequences.

  18. Determination of Curve Number for snowmelt-runoff floods in a small catchment

    Directory of Open Access Journals (Sweden)

    L. Hejduk

    2015-06-01

    Full Text Available One of the widely used methods for predicting flood runoff depth from ungauged catchments is the curve number (CN method, developed by Soil Conservation Service (SCS of US Department of Agriculture. The CN parameter can be computed directly from recorded rainfall depths and direct runoff volumes in case of existing data. In presented investigations, the CN parameter has been computed for snowmelt-runoff events based on snowmelt and rainfall measurements. All required data has been gathered for a small agricultural catchment (A = 23.4 km2 of Zagożdżonka river, located in Central Poland. The CN number received from 28 snowmelt-runoff events has been compared with CN computed from rainfall-runoff events for the same catchment. The CN parameter, estimated empirically varies from 64.0 to 94.8. The relation between CN and snowmelt depth was investigated in a similar procedure to relation between CN and rainfall depth.

  19. Modeling the isotopic evolution of snowpack and snowmelt: Testing a spatially distributed parsimonious approach.

    Science.gov (United States)

    Ala-Aho, Pertti; Tetzlaff, Doerthe; McNamara, James P; Laudon, Hjalmar; Kormos, Patrick; Soulsby, Chris

    2017-07-01

    Use of stable water isotopes has become increasingly popular in quantifying water flow paths and travel times in hydrological systems using tracer-aided modeling. In snow-influenced catchments, snowmelt produces a traceable isotopic signal, which differs from original snowfall isotopic composition because of isotopic fractionation in the snowpack. These fractionation processes in snow are relatively well understood, but representing their spatiotemporal variability in tracer-aided studies remains a challenge. We present a novel, parsimonious modeling method to account for the snowpack isotope fractionation and estimate isotope ratios in snowmelt water in a fully spatially distributed manner. Our model introduces two calibration parameters that alone account for the isotopic fractionation caused by sublimation from interception and ground snow storage, and snowmelt fractionation progressively enriching the snowmelt runoff. The isotope routines are linked to a generic process-based snow interception-accumulation-melt model facilitating simulation of spatially distributed snowmelt runoff. We use a synthetic modeling experiment to demonstrate the functionality of the model algorithms in different landscape locations and under different canopy characteristics. We also provide a proof-of-concept model test and successfully reproduce isotopic ratios in snowmelt runoff sampled with snowmelt lysimeters in two long-term experimental catchment with contrasting winter conditions. To our knowledge, the method is the first such tool to allow estimation of the spatially distributed nature of isotopic fractionation in snowpacks and the resulting isotope ratios in snowmelt runoff. The method can thus provide a useful tool for tracer-aided modeling to better understand the integrated nature of flow, mixing, and transport processes in snow-influenced catchments.

  20. Determination of Curve Number for snowmelt-runoff floods in a small catchment

    OpenAIRE

    L. Hejduk; A. Hejduk; K. Banasik

    2015-01-01

    One of the widely used methods for predicting flood runoff depth from ungauged catchments is the curve number (CN) method, developed by Soil Conservation Service (SCS) of US Department of Agriculture. The CN parameter can be computed directly from recorded rainfall depths and direct runoff volumes in case of existing data. In presented investigations, the CN parameter has been computed for snowmelt-runoff events based on snowmelt and rainfall measurements. All required data ...

  1. Isotope techniques in catchment behaviour studies with particular emphasis on snowmelt runoff investigations

    International Nuclear Information System (INIS)

    Yurtsever, Y.

    1984-05-01

    The dynamics of runoff occurring mainly by snowmelt have been investigated by the aid of environmental isotopes. Regular samples collected from river water and snow cover throughout 1978 to 1981 at two selected catchment basins in eastern Turkey were analysed for their oxygen-18, deuterium and tritium contents. The tritium results together with detailed hydrological and hydro-meteorological data have enabled to study the time distribution of various component flow systems involved in the total runoff resulting from snowmelt

  2. Charles Burchfield: "October Wind and Sunlight in the Woods."

    Science.gov (United States)

    Fitzgerald, Gaynell

    1986-01-01

    Based on Charles Burchfield's watercolor, "October Wind and Sunlight in the Woods," the goal of this lesson is to introduce students in grades seven through nine to Burchfield's use of symbolism. (JDH)

  3. Analytic Models for Sunlight Charging of a Rapidly Spinning Satellite

    National Research Council Canada - National Science Library

    Tautz, Maurice

    2003-01-01

    ... photoelectrons can be blocked by local potential barriers. In this report, we discuss two analytic models for sunlight charging of a rapidly spinning spherical satellite, both of which are based on blocked photoelectron currents...

  4. Sunlight-induced DNA damage in human mononuclear cells

    DEFF Research Database (Denmark)

    Møller, Peter; Wallin, Hakan; Holst, Erik

    2002-01-01

    of sunlight was comparable to the interindividual variation, indicating that sunlight exposure and the individual's background were the two most important determinants for the basal level of DNA damage. Influence of other lifestyle factors such as exercise, intake of foods, infections, and age could......In this study of 301 blood samples from 21 subjects, we found markedly higher levels of DNA damage (nonpyrimidine dimer types) in the summer than in the winter detected by single-cell gel electrophoresis. The level of DNA damage was influenced by the average daily influx of sunlight ... to blood sampling. The 3 and 6 day periods before sampling influenced DNA damage the most. The importance of sunlight was further emphasized by a positive association of the DNA damage level to the amount of time the subjects had spent in the sun over a 3 day period prior to the sampling. The effect...

  5. Effects of Sunlight Exposure on the Quality Parameters of Bottled ...

    African Journals Online (AJOL)

    PROF HORSFALL

    microbial population (total coliform) of the bottled water with increasing exposure to sunlight was observed. ... safe drinking water which has led to the tremendous ... degradation under high temperature (Bach et al., ..... Solar and photocatalytic.

  6. Ion enrichment of snowmelt water by processes within a podzolic soil

    International Nuclear Information System (INIS)

    Hazlett, P.W.; Foster, N.W.; English, M.C.

    1992-01-01

    Ion concentrations in snowmelt runoff, forest-floor percolate and mineral-soil percolate collected in a tolerant hardwood forest at the Turkey Lakes Watershed, ON, were determined during the spring snowmelt of 1986. The results were examined to assess the modification of snowmelt water after contact with the forest soil. Concentrations of NO 3 - increased from 17 to 201 μmol c L -1 and SO 4 2- increased from 25 to 107 μmol c L -1 as meltwater passed through the organic layers and the upper mineral-soil horizons. Mineralization of organic N and S, and desorption of So 4 2- from the soil, provide sources of these ions for leaching during the snowmelt period. Ion-exchange reactions in the forest floor and upper mineral soil resulted in a decrease in H + and an increase in Ca 2+ concentration is solution. In the steep topography of this forested basin, the altered snowmelt solutions are rapidly transported downslope towards the aquatic system by lateral flow. Processes within the forest soil may therefore play an important role in determining the effects of snowmelt water on surface water chemistry in the spring

  7. Accelerated stability testing of organic photovoltaics using concentrated sunlight

    DEFF Research Database (Denmark)

    Katz, Eugene A.; Manor, Assaf; Mescheloff, Asaf

    2012-01-01

    We suggest to use concentrated sunlight for accelerated studies of light-induced mechanisms in the degradation of organic photovoltaics (OPV) based on the polymer (P3HT)/fullerene (PCBM) bulk heterojunctions. Two particular cases of the degradation are reported.......We suggest to use concentrated sunlight for accelerated studies of light-induced mechanisms in the degradation of organic photovoltaics (OPV) based on the polymer (P3HT)/fullerene (PCBM) bulk heterojunctions. Two particular cases of the degradation are reported....

  8. Geometry and the Physics of Seasons

    Science.gov (United States)

    Khavrus, Vyacheslav; Shelevytsky, Ihor

    2012-01-01

    By means of a simple mathematical model recently developed by the authors (2010 "Phys. Educ." 45 641), the passage of the seasons on the Earth is simulated for arbitrary latitudes, taking into account sunlight attenuation in the atmosphere. The method developed can be used to predict a realistic value of the solar energy input (insolation) that…

  9. Rainfall and snow-melt triggered glacial lake outbursts: a systematic analysis of the Kedarnath (Uttarakhand, India), June 2013 disaster

    Science.gov (United States)

    Allen, Simon; Rastner, Philipp; Arora, Manohar; Huggel, Christian; Stoffel, Markus

    2015-04-01

    Heavy rainfall in early June 2013 triggered flash flooding and landslides throughout the Indian Himalayan state of Uttarakhand, killing more than 6000 people. The destruction of roads and trekking routes left around 100,000 pilgrims and tourists stranded. Most fatalities and damages resulted directly from a lake outburst and debris flow disaster originating from above the village of Kedarnath on June 16 and 17. Here we provide a first systematic analysis of the contributing factors leading to the Kedarnath disaster, both in terms of hydro-meteorological triggering (rainfall, snowmelt, and temperature) and topographic predisposition. Specifically, the topographic characteristics of the Charobari lake watershed above Kedarnath are compared with other glacial lakes across the northwestern Indian Himalayan states of Uttarakhand and Himachal Pradesh, and implications for glacier lake outburst hazard assessment in a changing climate are discussed. Our analysis suggests that the early onset of heavy monsoon rainfall (390 mm, June 10 - 17) immediately following a prolonged four week period of unusually rapid snow cover depletion and elevated streamflow is the crucial hydro-meteorological factor, resulting in slope saturation and significant runoff into the small seasonal glacial lake. Over a four week period the MODIS-derived snow covered area above Kedarnath decreased nearly 50%, from above average coverage in mid-May to well below average coverage by the second week of June. Such a rapid decrease has not been observed in the previous 13-year record, where the average decrease in snow covered area over the same four week window is only 15%. The unusual situation of the lake being dammed in a steep, unstable paraglacial environment, but fed entirely from snow-melt and rainfall within a fluvial dominated watershed is important in the context of this disaster. A simple scheme enabling large-scale recognition of such an unfavorable topographic setting is presented, and on the

  10. Adaptive fluid lens and sunlight redirection system : exploring a novel way of redirecting and altering sunlight in large span roofs

    NARCIS (Netherlands)

    Heinzelmann, F.; Bristogianni, T.; Teuffel, P.; Stouffs, R.; Sariyildiz, S.

    2013-01-01

    The paper describes a novel system to alter and redirect sunlight under large span roofs with the help of a fluid lens system. Focus lies on the computational design, testing, measurement and evaluation of the performance of a physical prototype.

  11. The role of upland wetlands in modulating snowmelt runoff in the semi-arid Andes

    Science.gov (United States)

    Hevia, Andres; Sproles, Eric; Soulsby, Chris; Tetzlaff, Doerthe

    2016-04-01

    The wetlands, or bofedales, of semi-arid northern central Chile (29°-32°S) provide a critical store of water that modulate spring snowmelt runoff. Water released from bofedales helps sustain flows throughout the dry portions of the year, providing fresh water to downstream residents and a robust tourist, agricultural, and mining economy. In the Río Claro watershed (30°S, 1515 km2, 800m to 5500 m a.s.l.) a series fourteen bofedales have formed at natural choke points in the valley bottoms of the headwater reaches. The highly erosive dynamic of this watershed provides ample sediment, and some of these bofedales are up to 30 m deep. Annual precipitation in the region is limited to 4-6 events annually that fall primarily as snow at elevations above 3500 m. The subsurface storage of the headwaters is limited by the steep terrain of the headwater catchments that are devoid of soils and primarily underlain by granite bedrock. Downstream, irrigated area has increased by 200% between 1985 and 2005, driven by the cultivation of table grapes for export. For over 70 years local water managers have flooded the bodfedales during spring runoff to augment late season flow when irrigation demand peaks. While this low-tech strategy has worked in the past, a recent 8-year drought has raised concerns over long-term water security. We apply geophysical and geographic measurements, water quality, and stable isotopic tracers to calculate the volume of water storage and residence times in the bofedales of Río Claro. This information will be used to evaluate the reliability of the bofedale system as compared to a proposed reservoir in the headwaters of the Río Claro. Additionally, estimating the storage and residence times of the will help reduce uncertainty for modeling efforts currently underway in Río Claro.

  12. Hg in snow cover and snowmelt waters in high-sulfide tailing regions (Ursk tailing dump site, Kemerovo region, Russia).

    Science.gov (United States)

    Gustaytis, M A; Myagkaya, I N; Chumbaev, A S

    2018-07-01

    Gold-bearing polymetallic Cu-Zn deposits of sulphur-pyrite ores were discovered in the Novo-Ursk region in the 1930s. The average content of mercury (Hg) was approximately 120 μg/g at the time. A comprehensive study of Hg distribution in waste of metal ore enrichment industry was carried out in the cold season on the tailing dump site and in adjacent areas. Mercury concentration in among snow particulate, dissolved and colloid fractions was determined. The maximal Hg content in particulate fraction from the waste tailing site ranged 230-573 μg/g. Such indices as the frequency of aerosol dust deposition events per units of time and area, enrichment factor and the total load allowed to establish that the territory of the tailing waste dump site had a snow cover highly contaminated with dust deposited at a rate of 247-480 mg/(m 2 ∙day). Adjacent areas could be considered as area with low Hg contamination rate with average deposition rate of 30 mg/(m 2 ∙day). The elemental composition of the aerosol dust depositions was determined as well, which allowed to reveal the extent of enrichment waste dispersion throughout adjacent areas. The amount of Hg entering environment with snowmelt water discharge was estimated. As a result of snowmelting, in 2014 the nearest to the dump site hydrographic network got Hg as 7.1 g with colloids and as 5880 g as particles. The results obtained allowed to assess the degree of Hg contamination of areas under the impact of metal enrichment industry. Copyright © 2018 Elsevier Ltd. All rights reserved.

  13. Bayesian analyses of seasonal runoff forecasts

    Science.gov (United States)

    Krzysztofowicz, R.; Reese, S.

    1991-12-01

    Forecasts of seasonal snowmelt runoff volume provide indispensable information for rational decision making by water project operators, irrigation district managers, and farmers in the western United States. Bayesian statistical models and communication frames have been researched in order to enhance the forecast information disseminated to the users, and to characterize forecast skill from the decision maker's point of view. Four products are presented: (i) a Bayesian Processor of Forecasts, which provides a statistical filter for calibrating the forecasts, and a procedure for estimating the posterior probability distribution of the seasonal runoff; (ii) the Bayesian Correlation Score, a new measure of forecast skill, which is related monotonically to the ex ante economic value of forecasts for decision making; (iii) a statistical predictor of monthly cumulative runoffs within the snowmelt season, conditional on the total seasonal runoff forecast; and (iv) a framing of the forecast message that conveys the uncertainty associated with the forecast estimates to the users. All analyses are illustrated with numerical examples of forecasts for six gauging stations from the period 1971 1988.

  14. Ultra-Accelerated Natural Sunlight Exposure Testing Facilities

    Science.gov (United States)

    Lewandowski, Allan A.; Jorgensen, Gary J.

    2004-11-23

    A multi-faceted concentrator apparatus for providing ultra-accelerated natural sunlight exposure testing for sample materials under controlled weathering conditions comprising: facets that receive incident natural sunlight, transmits VIS/NIR and reflects UV/VIS onto a secondary reflector that delivers a uniform flux of UV/VIS onto a sample exposure plane located near a center of a facet array in a chamber that provide concurrent levels of temperature and/or relative humidity at high levels of up to 100.times. of natural sunlight that allow sample materials to be subjected to accelerated irradiance exposure factors for a significant period of time of about 3 to 10 days to provide a corresponding time of about at least a years worth representative weathering of sample materials.

  15. Successful pacing using a batteryless sunlight-powered pacemaker.

    Science.gov (United States)

    Haeberlin, Andreas; Zurbuchen, Adrian; Schaerer, Jakob; Wagner, Joerg; Walpen, Sébastien; Huber, Christoph; Haeberlin, Heinrich; Fuhrer, Juerg; Vogel, Rolf

    2014-10-01

    Today's cardiac pacemakers are powered by batteries with limited energy capacity. As the battery's lifetime ends, the pacemaker needs to be replaced. This surgical re-intervention is costly and bears the risk of complications. Thus, a pacemaker without primary batteries is desirable. The goal of this study was to test whether transcutaneous solar light could power a pacemaker. We used a three-step approach to investigate the feasibility of sunlight-powered cardiac pacing. First, the harvestable power was estimated. Theoretically, a subcutaneously implanted 1 cm(2) solar module may harvest ∼2500 µW from sunlight (3 mm implantation depth). Secondly, ex vivo measurements were performed with solar cells placed under pig skin flaps exposed to a solar simulator and real sunlight. Ex vivo measurements under real sunlight resulted in a median output power of 4941 µW/cm(2) [interquartile range (IQR) 3767-5598 µW/cm(2), median skin flap thickness 3.0 mm (IQR 2.7-3.3 mm)]. The output power strongly depended on implantation depth (ρSpearman = -0.86, P pacemaker powered by a 3.24 cm(2) solar module was implanted in vivo in a pig to measure output power and to pace. In vivo measurements showed a median output power of >3500 µW/cm(2) (skin flap thickness 2.8-3.84 mm). Successful batteryless VVI pacing using a subcutaneously implanted solar module was performed. Based on our results, we estimate that a few minutes of direct sunlight (irradiating an implanted solar module) allow powering a pacemaker for 24 h using a suitable energy storage. Thus, powering a pacemaker by sunlight is feasible and may be an alternative energy supply for tomorrow's pacemakers. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2014. For permissions please email: journals.permissions@oup.com.

  16. Application of snowmelt runoff model (SRM in mountainous watersheds: A review

    Directory of Open Access Journals (Sweden)

    Shalamu Abudu

    2012-06-01

    Full Text Available The snowmelt runoff model (SRM has been widely used in simulation and forecast of streamflow in snow-dominated mountainous basins around the world. This paper presents an overall review of worldwide applications of SRM in mountainous watersheds, particularly in data-sparse watersheds of northwestern China. Issues related to proper selection of input climate variables and parameters, and determination of the snow cover area (SCA using remote sensing data in snowmelt runoff modeling are discussed through extensive review of literature. Preliminary applications of SRM in northwestern China have shown that the model accuracies are relatively acceptable although most of the watersheds lack measured hydro-meteorological data. Future research could explore the feasibility of modeling snowmelt runoff in data-sparse mountainous watersheds in northwestern China by utilizing snow and glacier cover remote sensing data, geographic information system (GIS tools, field measurements, and innovative ways of model parameterization.

  17. Modulation of snow reflectance and snowmelt from Central Asian glaciers by anthropogenic black carbon.

    Science.gov (United States)

    Schmale, Julia; Flanner, Mark; Kang, Shichang; Sprenger, Michael; Zhang, Qianggong; Guo, Junming; Li, Yang; Schwikowski, Margit; Farinotti, Daniel

    2017-01-12

    Deposited mineral dust and black carbon are known to reduce the albedo of snow and enhance melt. Here we estimate the contribution of anthropogenic black carbon (BC) to snowmelt in glacier accumulation zones of Central Asia based on in-situ measurements and modelling. Source apportionment suggests that more than 94% of the BC is emitted from mostly regional anthropogenic sources while the remaining contribution comes from natural biomass burning. Even though the annual deposition flux of mineral dust can be up to 20 times higher than that of BC, we find that anthropogenic BC causes the majority (60% on average) of snow darkening. This leads to summer snowmelt rate increases of up to 6.3% (7 cm a -1 ) on glaciers in three different mountain environments in Kyrgyzstan, based on albedo reduction and snowmelt models.

  18. Experimental measurement and modeling of snow accumulation and snowmelt in a mountain microcatchment

    Science.gov (United States)

    Danko, Michal; Krajčí, Pavel; Hlavčo, Jozef; Kostka, Zdeněk; Holko, Ladislav

    2016-04-01

    Fieldwork is a very useful source of data in all geosciences. This naturally applies also to the snow hydrology. Snow accumulation and snowmelt are spatially very heterogeneous especially in non-forested, mountain environments. Direct field measurements provide the most accurate information about it. Quantification and understanding of processes, that cause these spatial differences are crucial in prediction and modelling of runoff volumes in spring snowmelt period. This study presents possibilities of detailed measurement and modeling of snow cover characteristics in a mountain experimental microcatchment located in northern part of Slovakia in Western Tatra mountains. Catchment area is 0.059 km2 and mean altitude is 1500 m a.s.l. Measurement network consists of 27 snow poles, 3 small snow lysimeters, discharge measurement device and standard automatic weather station. Snow depth and snow water equivalent (SWE) were measured twice a month near the snow poles. These measurements were used to estimate spatial differences in accumulation of SWE. Snowmelt outflow was measured by small snow lysimeters. Measurements were performed in winter 2014/2015. Snow water equivalent variability was very high in such a small area. Differences between particular measuring points reached 600 mm in time of maximum SWE. The results indicated good performance of a snow lysimeter in case of snowmelt timing identification. Increase of snowmelt measured by the snow lysimeter had the same timing as increase in discharge at catchment's outlet and the same timing as the increase in air temperature above the freezing point. Measured data were afterwards used in distributed rainfall-runoff model MIKE-SHE. Several methods were used for spatial distribution of precipitation and snow water equivalent. The model was able to simulate snow water equivalent and snowmelt timing in daily step reasonably well. Simulated discharges were slightly overestimated in later spring.

  19. Severe soil frost reduced losses of carbon and nitrogen from the forest floor during simulated snowmelt: A laboratory experiment

    Science.gov (United States)

    Andrew B. Reinmann; Pamela H. Templer; John L. Campbell

    2012-01-01

    Considerable progress has been made in understanding the impacts of soil frost on carbon (C) and nitrogen (N) cycling, but the effects of soil frost on C and N fluxes during snowmelt remain poorly understood. We conducted a laboratory experiment to determine the effects of soil frost on C and N fluxes from forest floor soils during snowmelt. Soil cores were collected...

  20. Sunlight-enhanced catalytic degradation over Ag–CuO ...

    Indian Academy of Sciences (India)

    Herein, we report sunlight-activated photo-catalysis response of direct current radio frequency (DC/RF)-sputtered Ag–CuO nanoparticles thin films.We have adopted this approach for facile removal and easy recovery of thin filmsafter use. Ag was incorporated at 2.5 and 5.4 wt% with reference to pure CuO. Structural ...

  1. Effect of sunlight, transport and storage vessels on drinking water ...

    African Journals Online (AJOL)

    Effect of sunlight, transport and storage vessels on drinking water quality in rural Ghana. ... on drinking water quality in rural Ghana. K Obiri-Danso, E Amevor, LA Andoh, K Jones ... Full Text: EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT

  2. Reversible degradation of inverted organic solar cells by concentrated sunlight

    International Nuclear Information System (INIS)

    Tromholt, Thomas; Krebs, Frederik C; Manor, Assaf; Katz, Eugene A

    2011-01-01

    Concentrated sunlight was used to study the performance response of inverted P3HT:PCBM organic solar cells after exposure to high intensity sunlight. Correlations of efficiency as a function of solar intensity were established in the range of 0.5-15 suns at three different stages: for a pristine cell, after 30 min exposure at 5 suns and after 30 min of rest in the dark. High intensity exposure introduced a major performance decrease for all solar intensities, followed by a partial recovery of the lost performance over time: at 1 sun only 6% of the initial performance was conserved after the high intensity exposure, while after rest the performance had recovered to 60% of the initial value. The timescale of the recovery effect was studied by monitoring the cell performance at 1 sun after high intensity exposure. This showed that cell performance was almost completely restored after 180 min. The transient state is believed to be a result of the breakdown of the diode behaviour of the ZnO electron transport layer by O 2 desorption, increasing the hole conductivity. These results imply that accelerated degradation of organic solar cells by concentrated sunlight is not a straightforward process, and care has to be taken to allow for a sound accelerated lifetime assessment based on concentrated sunlight.

  3. Electricity from Sunlight: The Future of Photovoltaics. Worldwatch Paper 52.

    Science.gov (United States)

    Flavin, Christopher

    Solar photovoltaic cells have been called the ultimate energy technology, environmentally benign and without moving parts, solar cells directly convert sunlight into electricity. Photovoltaic energy conversion is fundamentally different from all other forms of electricity generation. Without turbines, generators or other mechanical equipment, it…

  4. Effect of sunlight shielding on leaf structure and amino acids ...

    African Journals Online (AJOL)

    Light sensitive albino tea cultivar 'Jinguang' (Camellia sinensis) which grows albinism leaf in yellow colour, results to high level of amino acids but low levels of photosynthetic pigments including chlorophylls, neoxanthin, violaxanthin, phytoxanthin and β-carotene when it is exposed to high sunlight illumination in the ...

  5. Dietary calcium intake and sunlight exposure among children aged ...

    African Journals Online (AJOL)

    Nutritional rickets can be caused by either or both calcium and vitamin D deficiencies, and can frequently occur in Africa. In Ethiopia, limited evidence exists regarding the calcium intake of children and their sunlight exposure practices. The purpose of this study was to assess information regarding dietary calcium intake and ...

  6. Turning Sunlight into Electricity-Inorganic Solar Cells and Beyond

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 16; Issue 12. Turning Sunlight into Electricity - Inorganic Solar Cells and Beyond. A K Shukla. Volume 16 Issue 12 December 2011 pp 1294-1302. Fulltext. Click here to view fulltext PDF. Permanent link:

  7. Magnitudes and timing of seasonal peak snowpack water equivalents in Arizona: A preliminary study of the possible effects of recent climatic change

    Science.gov (United States)

    Peter F. Ffolliott; Gerald J. Gottfried

    2010-01-01

    Field measurements and computer-based predictions suggest that the magnitudes of seasonal peak snowpack water equivalents are becoming less and the timing of these peaks is occurring earlier in the snowmelt-runoff season of the western United States. These changes in peak snowpack conditions have often been attributed to a warming of the regional climate. To determine...

  8. [Soil infiltration of snowmelt water in the southern Gurbantunggut Desert, Xinjiang, China].

    Science.gov (United States)

    Hu, Shun-jun; Chen, Yong-bao; Zhu, Hai

    2015-04-01

    Soil infiltration of snow-melt water is an important income item of water balance in arid desert. The soil water content in west slope, east slope and interdune of sand dune in the southern Gurbantunggut Desert was monitored before snowfall and after snow melting during the winters of 2012-2013 and 2013-2014. According to the principle of water balance, soil infiltration of snow-melt in the west slope, east slope, interdune and landscape scale was calculated, and compared with the results measured by cylinder method. The results showed that the soil moisture recharge from unfrozen layer of unsaturated soil to surface frozen soil was negligible because the soil moisture content before snowfall was lower, soil infiltration of snow-melt water was the main source of soil water of shallow soil, phreatic water did not evaporate during freezing period, and did not get recharge after the snow melting. Snowmelt water in the west slope, east slope, interdune and landscape scale were 20-43, 27-43, 32-45, 26-45 mm, respectively.

  9. Spring Snowmelt and Mercury Export from a Forested Catchment in the Czech Republic, Central Europe

    Czech Academy of Sciences Publication Activity Database

    Navrátil, Tomáš; Rohovec, Jan; Hojdová, Maria; Vach, Marek

    2011-01-01

    Roč. 86, č. 6 (2011), s. 670-675 ISSN 0007-4861 R&D Projects: GA ČR GP526/07/P170 Institutional research plan: CEZ:AV0Z30130516 Keywords : mercury * DOC * acidified * catchment * snowmelt Subject RIV: DD - Geochemistry Impact factor: 1.018, year: 2011

  10. A DESIGN METHOD FOR RETAINING WALL BASED ON RETURN PERIOD OF RAINFALL AND SNOWMELT

    Science.gov (United States)

    Ebana, Ryo; Uehira, Kenichiro; Yamada, Tadashi

    The main purpose of this study is to develop a new design method for the retaining wall in a cold district. In the cold district, snowfall and snowmelt is one of the main factors in sediment related disaster. However, the effect of the snowmelt is not being taken account of sediment disasters precaution and evacuation system. In this study, we target at past slope failure disaster and quantitatively evaluate that the effect of rainfall and snowmelt on groundwater level and then verify the stability of slope. Water supplied on the slope was determined from the probabilistic approach of the snowmelt using DegreeDay method in this study. Furthermore, a slope stability analysis was carried out based on the ground water level that was obtained from the unsaturated infiltration flow with the saturated seepage flow simulations. From the result of the slope stability analysis, it was found that the effect of ground water level on the stability of slope is much bigger than that of other factors.

  11. Stream Nitrogen Inputs Reflect Groundwater Across a Snowmelt-Dominated Montane to Urban Watershed.

    Science.gov (United States)

    Hall, Steven J; Weintraub, Samantha R; Eiriksson, David; Brooks, Paul D; Baker, Michelle A; Bowen, Gabriel J; Bowling, David R

    2016-02-02

    Snowmelt dominates the hydrograph of many temperate montane streams, yet little work has characterized how streamwater sources and nitrogen (N) dynamics vary across wildland to urban land use gradients in these watersheds. Across a third-order catchment in Salt Lake City, Utah, we asked where and when groundwater vs shallow surface water inputs controlled stream discharge and N dynamics. Stream water isotopes (δ(2)H and δ(18)O) reflected a consistent snowmelt water source during baseflow. Near-chemostatic relationships between conservative ions and discharge implied that groundwater dominated discharge year-round across the montane and urban sites, challenging the conceptual emphasis on direct stormwater inputs to urban streams. Stream and groundwater NO3(-) concentrations remained consistently low during snowmelt and baseflow in most montane and urban stream reaches, indicating effective subsurface N retention or denitrification and minimal impact of fertilizer or deposition N sources. Rather, NO3(-) concentrations increased 50-fold following urban groundwater inputs, showing that subsurface flow paths potentially impact nutrient loading more than surficial land use. Isotopic composition of H2O and NO3(-) suggested that snowmelt-derived urban groundwater intercepted NO3(-) from leaking sewers. Sewer maintenance could potentially mitigate hotspots of stream N inputs at mountain/valley transitions, which have been largely overlooked in semiarid urban ecosystems.

  12. The role of microbes in snowmelt and radiative forcing on an Alaskan icefield

    Science.gov (United States)

    Ganey, Gerard Q.; Loso, Michael G.; Burgess, Annie Bryant; Dial, Roman J.

    2017-10-01

    A lack of liquid water limits life on glaciers worldwide but specialized microbes still colonize these environments. These microbes reduce surface albedo, which, in turn, could lead to warming and enhanced glacier melt. Here we present results from a replicated, controlled field experiment to quantify the impact of microbes on snowmelt in red-snow communities. Addition of nitrogen-phosphorous-potassium fertilizer increased alga cell counts nearly fourfold, to levels similar to nitrogen-phosphorus-enriched lakes; water alone increased counts by half. The manipulated alga abundance explained a third of the observed variability in snowmelt. Using a normalized-difference spectral index we estimated alga abundance from satellite imagery and calculated microbial contribution to snowmelt on an icefield of 1,900 km2. The red-snow area extended over about 700 km2, and in this area we determined that microbial communities were responsible for 17% of the total snowmelt there. Our results support hypotheses that snow-dwelling microbes increase glacier melt directly in a bio-geophysical feedback by lowering albedo and indirectly by exposing low-albedo glacier ice. Radiative forcing due to perennial populations of microbes may match that of non-living particulates at high latitudes. Their contribution to climate warming is likely to grow with increased melt and nutrient input.

  13. Effects of experimental snowmelt and rain on dispersal of six plant species

    NARCIS (Netherlands)

    Sarneel, J. M.

    2016-01-01

    Water flows affect dispersal of propagules of many plant species, and rivers and streams are therefore very important dispersal vectors. However, small water flows such as trough rain and snowmelt are much more common, but their effects on dispersal are barely studied. The importance of this form of

  14. High Arctic plant phenology is determined by snowmelt patterns but duration of phenological periods is fixed

    DEFF Research Database (Denmark)

    Semenchuk, Philipp R.; Gillespie, Mark A K; Rumpf, Sabine B.

    2016-01-01

    The duration of specific periods within a plant's life cycle are critical for plant growth and performance. In the High Arctic, the start of many of these phenological periods is determined by snowmelt date, which may change in a changing climate. It has been suggested that the end of these periods...

  15. Alkalinity generation in snowmelt and rain runoff during short distance flow over rock

    Science.gov (United States)

    James L. Clayton

    1998-01-01

    High-elevation ecosystems in the western United States typically have patchy, discontinuous areas of surficial soils surrounded by large areas of rock outcrop, talus, and scree. Snowmelt and precipitation that percolate through soil increase in alkalinity, principally by increasing base cation concentration through cation exchange, and by decreasing acid anion...

  16. Controls on deep drainage beneath the root soil zone in snowmelt-dominated environments

    Science.gov (United States)

    Hammond, J. C.; Harpold, A. A.; Kampf, S. K.

    2017-12-01

    Snowmelt is the dominant source of streamflow generation and groundwater recharge in many high elevation and high latitude locations, yet we still lack a detailed understanding of how snowmelt is partitioned between the soil, deep drainage, and streamflow under a variety of soil, climate, and snow conditions. Here we use Hydrus 1-D simulations with historical inputs from five SNOTEL snow monitoring sites in each of three regions, Cascades, Sierra, and Southern Rockies, to investigate how inter-annual variability on water input rate and duration affects soil saturation and deep drainage. Each input scenario was run with three different soil profiles of varying hydraulic conductivity, soil texture, and bulk density. We also created artificial snowmelt scenarios to test how snowmelt intermittence affects deep drainage. Results indicate that precipitation is the strongest predictor (R2 = 0.83) of deep drainage below the root zone, with weaker relationships observed between deep drainage and snow persistence, peak snow water equivalent, and melt rate. The ratio of deep drainage to precipitation shows a stronger positive relationship to melt rate suggesting that a greater fraction of input becomes deep drainage at higher melt rates. For a given amount of precipitation, rapid, concentrated snowmelt may create greater deep drainage below the root zone than slower, intermittent melt. Deep drainage requires saturation below the root zone, so saturated hydraulic conductivity serves as a primary control on deep drainage magnitude. Deep drainage response to climate is mostly independent of soil texture because of its reliance on saturated conditions. Mean water year saturations of deep soil layers can predict deep drainage and may be a useful way to compare sites in soils with soil hydraulic porosities. The unit depth of surface runoff often is often greater than deep drainage at daily and annual timescales, as snowmelt exceeds infiltration capacity in near-surface soil layers

  17. Inter-annual and spatial variability in hillslope runoff and mercury flux during spring snowmelt.

    Science.gov (United States)

    Haynes, Kristine M; Mitchell, Carl P J

    2012-08-01

    Spring snowmelt is an important period of mercury (Hg) export from watersheds. Limited research has investigated the potential effects of climate variability on hydrologic and Hg fluxes during spring snowmelt. The purpose of this research was to assess the potential impacts of inter-annual climate variability on Hg mobility in forested uplands, as well as spatial variability in hillslope hydrology and Hg fluxes. We compared hydrological flows, Hg and solute mobility from three adjacent hillslopes in the S7 watershed of the Marcell Experimental Forest, Minnesota during two very different spring snowmelt periods: one following a winter (2009-2010) with severely diminished snow accumulation (snow water equivalent (SWE) = 48 mm) with an early melt, and a second (2010-2011) with significantly greater winter snow accumulation (SWE = 98 mm) with average to late melt timing. Observed inter-annual differences in total Hg (THg) and dissolved organic carbon (DOC) yields were predominantly flow-driven, as the proportion by which solute yields increased was the same as the increase in runoff. Accounting for inter-annual differences in flow, there was no significant difference in THg and DOC export between the two snowmelt periods. The spring 2010 snowmelt highlighted the important contribution of melting soil frost in the timing of a considerable portion of THg exported from the hillslope, accounting for nearly 30% of the THg mobilized. Differences in slope morphology and soil depths to the confining till layer were important in controlling the large observed spatial variability in hydrological flowpaths, transmissivity feedback responses, and Hg flux trends across the adjacent hillslopes.

  18. Winter Ground Temperatures Control Snowmelt DOC Export From a Discontinuous Permafrost Watershed: A Multi-Year Perspective

    Science.gov (United States)

    Carey, S. K.

    2006-12-01

    For discontinuous and continuous permafrost watersheds, the largest mass flux of dissolved organic carbon (DOC) occurs during the snowmelt period. During this time, available allochtonous organic carbon that has accumulated over the winter in frozen organic soils is rapidly flushed to the basin outlet. While this process has been observed now in many river systems of different size and location, there have been few inter-annual reports on the mass of DOC loss and the factors controlling its variability during freshet. Hydrological and DOC fluxes were recorded for the 2002, 2003 and 2006 snowmelt season with supplementary over-winter data for an 8 square kilometer sub-basin (Granger Basin) of the Wolf Creek Research Basin, Yukon Territory, Canada. Granger Basin is an alpine catchment above treeline underlain with discontinuous permafrost (approximately 70 %) and has widespread surface organic soils up to 0.4 m in thickness. Pre-melt snow water equivalent varied widely throughout the basin, yet was greatest in 2006, followed by 2002 and 2003. Ground temperatures were notably colder throughout the 2003 winter compared with 2006 and 2002. For all years, discharge began in mid-May, and was a continuous event in 2002 and 2006. In 2003 four distinct melt-periods were observed due to rising and falling temperatures. During freshet, stream DOC concentration increased rapidly from 15 mg C/L on the first ascending limb of the hydrograph in each year. In 2003, DOC was largely flushed from the catchment several weeks prior to peak freshet. DOC concentration in wells and piezometers followed a similar pattern to streamflow DOC, with 2003 groundwater DOC concentrations less than 2002 and 2006. The total mass flux of DOC during freshet was 0.85, 0.45 and 1.01 g C/m2 for 2002, 2003 and 2006 respectively. Despite differences in pre-melt snow accumulation, the timing of melt and the volume of discharge, it appears that spring DOC export is largely controlled by over-winter ground

  19. Natural sunlight bleaching of the aluminum center in quartz

    International Nuclear Information System (INIS)

    Lin Min; Yin Gongming; Han Kongyan; Bao Jifei; Liu Jingwei; Jia Li

    2007-01-01

    The effect of sunlight bleaching on ESR signals from the aluminum center in quartz is reported for two samples of sand-sized quartz, one from a granite and one from a beach sand. The grains were exposed to direct sunlight for periods of time up to 500 h, with bleaching carried out in four different cities in China that are from 50 to 3600 m above sea level. Each sample bleached to the same residual level, ∼55% for the granite and 80% for the beach sand of the initial value after a 200 Gy dose had been given. After 200 h, the bleaching level reached was independent of the height above sea level

  20. Intensity correlation imaging with sunlight-like source

    Science.gov (United States)

    Wang, Wentao; Tang, Zhiguo; Zheng, Huaibin; Chen, Hui; Yuan, Yuan; Liu, Jinbin; Liu, Yanyan; Xu, Zhuo

    2018-05-01

    We show a method of intensity correlation imaging of targets illuminated by a sunlight-like source both theoretically and experimentally. With a Faraday anomalous dispersion optical filter (FADOF), we have modulated the coherence time of a thermal source up to 0.167 ns. And we carried out measurements of temporal and spatial correlations, respectively, with an intensity interferometer setup. By skillfully using the even Fourier fitting on the very sparse sampling data, the images of targets are successfully reconstructed from the low signal-noise-ratio(SNR) interference pattern by applying an iterative phase retrieval algorithm. The resulting imaging quality is as well as the one obtained by the theoretical fitting. The realization of such a case will bring this technique closer to geostationary satellite imaging illuminated by sunlight.

  1. Relationships between stream nitrate concentration and spatially distributed snowmelt in high-elevation catchments of the western U.S.

    Science.gov (United States)

    Perrot, Danielle; Molotch, Noah P.; Williams, Mark W.; Jepsen, Steven M.; Sickman, James O.

    2014-11-01

    This study compares stream nitrate (NO3-) concentrations to spatially distributed snowmelt in two alpine catchments, the Green Lakes Valley, Colorado (GLV4) and Tokopah Basin, California (TOK). A snow water equivalent reconstruction model and Landsat 5 and 7 snow cover data were used to estimate daily snowmelt at 30 m spatial resolution in order to derive indices of new snowmelt areas (NSAs). Estimates of NSA were then used to explain the NO3- flushing behavior for each basin over a 12 year period (1996-2007). To identify the optimal method for defining NSAs and elucidate mechanisms underlying catchment NO3- flushing, we conducted a series of regression analyses using multiple thresholds of snowmelt based on temporal and volumetric metrics. NSA indices defined by volume of snowmelt (e.g., snowmelt ≤ 30 cm) rather than snowmelt duration (e.g., snowmelt ≤ 9 days) were the best predictors of stream NO3- concentrations. The NSA indices were better correlated with stream NO3- concentration in TOK (average R2= 0.68) versus GLV4 (average R2= 0.44). Positive relationships between NSA and stream NO3- concentration were observed in TOK with peak stream NO3- concentration occurring on the rising limb of snowmelt. Positive and negative relationships between NSA and stream NO3- concentration were found in GLV4 with peak stream NO3- concentration occurring as NSA expands. Consistent with previous works, the contrasting NO3- flushing behavior suggests that streamflow in TOK was primarily influenced by overland flow and shallow subsurface flow, whereas GLV4 appeared to be more strongly influenced by deeper subsurface flow paths.

  2. Sunlight technologies for photochemical deactivation of organic pollutants in water

    Energy Technology Data Exchange (ETDEWEB)

    Acher, A.; Fischer, E.; Tornheim, R. [The Volcani Center, Inst. of Soils and Water, Bet Dagan (Israel); Manor, Y. [Sheba Medical Center, Central Virology Lab., Ramat Gan (Israel)

    1997-12-31

    Sensitized-photochemical oxidation methods aimed at use in water treatment technologies for deactivation of biotic (microorganisms) and/or of xenobiotic (pesticides) pollutants in water were developed using global solar radiation or concentrated sunlight (up to 250 suns). The solar global radiation was used either for detoxification of industrial waste water from a pesticide factory to allow their discharge into the urban sewer, or for disinfection of domestric effluents to be used in crop irrigation. The disinfection process was eventually carried out in an experimental pilot-scale plant, capable of disinfection up to 50 m{sup 3}/h of effluent supplied by an activated sludge sewage treatment plant located in Tel-Aviv area. The treated effluents did not show any regrowth of the microorganisms during 7 days. The solar concentrated radiation experiments performed using facilities of the Sun Tower of The Weizman Institute of Science, Rehovot. The concentrated sunlight was provided by different combination of several computer controlled heliostates, up to 8, that track the sun and focus the received sunlight onto the target situated on the roof of the sun-tower. The sunlight intensities measured on the target reached up to 200 kW/m{sup 2}. The experiments were performed either batch- or continuous-wise. The water-samples exposed to disinfection were the above effluent, filtered and supplemented with vaccine strain poliovirus or with different concentrations of an industrial potential pollutant (bromacil), MB 2 mg/L and two concentrations of dissolved oxygen (8.0 or 40.0 mg O{sub 2}/L). An exposure time of 2-3 seconds at 150 kW/m{sup 2} was decreased the microorganisms alive (counts) by five orders of magnitude. A comparison between the two above water treatment technologies is presented. (orig./SR)

  3. Passive radiative cooling below ambient air temperature under direct sunlight.

    Science.gov (United States)

    Raman, Aaswath P; Anoma, Marc Abou; Zhu, Linxiao; Rephaeli, Eden; Fan, Shanhui

    2014-11-27

    Cooling is a significant end-use of energy globally and a major driver of peak electricity demand. Air conditioning, for example, accounts for nearly fifteen per cent of the primary energy used by buildings in the United States. A passive cooling strategy that cools without any electricity input could therefore have a significant impact on global energy consumption. To achieve cooling one needs to be able to reach and maintain a temperature below that of the ambient air. At night, passive cooling below ambient air temperature has been demonstrated using a technique known as radiative cooling, in which a device exposed to the sky is used to radiate heat to outer space through a transparency window in the atmosphere between 8 and 13 micrometres. Peak cooling demand, however, occurs during the daytime. Daytime radiative cooling to a temperature below ambient of a surface under direct sunlight has not been achieved because sky access during the day results in heating of the radiative cooler by the Sun. Here, we experimentally demonstrate radiative cooling to nearly 5 degrees Celsius below the ambient air temperature under direct sunlight. Using a thermal photonic approach, we introduce an integrated photonic solar reflector and thermal emitter consisting of seven layers of HfO2 and SiO2 that reflects 97 per cent of incident sunlight while emitting strongly and selectively in the atmospheric transparency window. When exposed to direct sunlight exceeding 850 watts per square metre on a rooftop, the photonic radiative cooler cools to 4.9 degrees Celsius below ambient air temperature, and has a cooling power of 40.1 watts per square metre at ambient air temperature. These results demonstrate that a tailored, photonic approach can fundamentally enable new technological possibilities for energy efficiency. Further, the cold darkness of the Universe can be used as a renewable thermodynamic resource, even during the hottest hours of the day.

  4. Diagnosing land management and climate change impacts on snowmelt in semi-arid agricultural cold regions with an improved snowmelt model

    Science.gov (United States)

    Harder, P.; Pomeroy, J. W.; Helgason, W.

    2017-12-01

    Spring snowmelt is the most important hydrological event in semi-arid agricultural cold regions, recharging soil moisture and generating the majority of annual runoff. Adoption of no-till agricultural practices means vast areas of the Canadian Prairies, and other analogous regions, are characterized by standing crop stubble. The emergence of stubble during snowmelt will have important implications for the snowpack energy balance. In addition, spatiotemporally dynamic snowcover heterogeneity leads to enhancement of turbulent flux contributions to melt by advection of energy from warm moist bare ground to snow. Stubble emergence and advection are generally unaccounted for in snow models. To address these challenges a stubble-snow-atmosphere surface energy balance model is developed that relates stubble parameters to the snow surface energy balance. Existing fractal understandings of snowcover geometry are applied to a conceptualized boundary layer integration model to estimate a sensible and latent heat advection efficiency. The small-scale nature of stubble-snow-atmosphere interactions makes direct validation of the energy balance terms challenging. However, the energy balance estimates are assessed by comparing to measured snow and stubble surface temperatures, snow surface incoming shortwave radiation and areal average turbulent fluxes. Advection estimates are validated from a two-dimensional air temperature, water vapor and windspeed profiles. Snowcover geometry relationships are validated/updated with unmanned air vehicle observations. Observations for model assessment occurred in 2015 and 2016 on wheat and canola stubble fields in north-central Saskatchewan, Canada. The model is not calibrated to melt rates, yet compares well with available observations, providing confidence in the model structure and parameterization. Sensitivity analysis using the model revealed compensatory relationships in energy balance terms resulting in limited reduction of energy

  5. The effects of sunlight exposure on the neutron response of CN-85 track detector

    International Nuclear Information System (INIS)

    Ahmad, N.; Mirza, N.M.; Mirza, S.K.; Tufail, M.

    1996-01-01

    The effect of sunlight exposure on the neutron response of CN-85 track detectors has been studied. It has been observed that the response during the first 28 days of sunlight exposure is slightly enhanced (10%) and then deceases continuously with increase in the sunlight exposure. After 84 days of sunlight exposure the response of the exposed detector relative to an unexposed detector is only 22%. It is also observed that the response can not be maintained by wrapping the CN-85 etch track detectors in typewriter black carbon papers if they are exposed to sunlight. (author)

  6. New Technology and Experimental Study on Snow-Melting Heated Pavement System in Tunnel Portal

    Directory of Open Access Journals (Sweden)

    Jinxing Lai

    2015-01-01

    Full Text Available In recent years, with the rapid growth of economy and sharp rise of motor vehicles in China, the pavement skid resistance in tunnel portals has become increasingly important in cold region. However, the deicing salt, snow removal with machine, and other antiskid measures adopted by highway maintenance division have many limitations. To improve the treatment effect, we proposed a new snow-melting approach employing electric heat tracing, in which heating cables are installed in the structural layer of road. Through the field experiment, laboratory experiment, and numerical investigation, structure type, heating power, and preheating time of the flexible pavement heating system in tunnel portal were systematically analyzed, and advantages of electric heat tracing technology in improving the pavement skid resistance in tunnel portal were also presented. Therefore, such new technology, which offers new snow-melting methods for tunnel portal, bridge, mountainous area, and large longitudinal slope in cold region, has promising prospect for extensive application.

  7. New Technology and Experimental Study on Snow-Melting Heated Pavement System in Tunnel Portal

    OpenAIRE

    Lai, Jinxing; Qiu, Junling; Chen, Jianxun; Fan, Haobo; Wang, Ke

    2015-01-01

    In recent years, with the rapid growth of economy and sharp rise of motor vehicles in China, the pavement skid resistance in tunnel portals has become increasingly important in cold region. However, the deicing salt, snow removal with machine, and other antiskid measures adopted by highway maintenance division have many limitations. To improve the treatment effect, we proposed a new snow-melting approach employing electric heat tracing, in which heating cables are installed in the structural ...

  8. Flow-Control Systems Proof of Concept for Snowmelt Runoff at McMurdo Station, Antarctica

    Science.gov (United States)

    2017-01-01

    ER D C/ CR RE L TR -1 7- 1 Engineering for Polar Operations , Logistics, and Research (EPOLAR) Flow-Control Systems Proof of Concept for...January 2017 Flow-Control Systems Proof of Concept for Snowmelt Runoff at McMurdo Station, Antarctica Rosa Affleck U.S. Army Engineer Research and...runoff can be extreme where the flow can overwhelm both the drainage system and the operations and maintenance (O&M) crew. CRREL has been involved

  9. 50 years of change at 14 headwater snowmelt-dominated watersheds in Wyoming

    Science.gov (United States)

    Voutchkova, D. D.; Miller, S. N.

    2017-12-01

    Wyoming is a headwater state contributing to the water resources of four major US basins: Columbia River, Colorado River, Great Basin, and Missouri River. Most of the annual precipitation in this semi-arid state is received at high elevations as snow. Water availability for drinking water supply, reservoir storage, industrial, agricultural, and ecological needs - all depends on the variable and potentially changing annual snowmelt. Thus, characterizing snowmelt and snowmelt-dominated runoff variability and change at high-elevation headwater watersheds in Wyoming is of utmost importance. Next to quantifying variability and changes in total precipitation, snow-water equivalent (SWE), annual runoff and low flows at 14 selected and representative high-elevation watersheds during the previous 50 years, we also explore past watershed disturbances. Wildfires, forest management (e.g. timber harvest), and recent bark beetle outbakes have altered the vegetation and potentially the hydrology of these high-elevation watersheds. We present a synthesis and trend analysis of 49-75 complete water years (wy) of daily streamflow data for 14 high-elevation watersheds, 25-36 complete wy of daily SWE and precipitation data for the closest SNOTEL stations, and spatiotemporal data on burned areas for 20 wy, tree mortality for 18 wy, timber harvest during the 20th century, as well as overview on legacy tie-drive related distrbances. These results are discussed with respect to the differing watershed characteristics in order to present a spectrum of possible hydrologic responses. The importance of our work lies in extending our understanding of snowmelt headwater annual runoff and low-flow dynamics in Wyoming specifically. Such regional synthesis would inform and facilitate water managers and planners both at local state-wide level, but also in the intermountain US West.

  10. Modelling Snowmelt Runoff under Climate Change Scenarios in an Ungauged Mountainous Watershed, Northwest China

    Directory of Open Access Journals (Sweden)

    Yonggang Ma

    2013-01-01

    Full Text Available An integrated modeling system has been developed for analyzing the impact of climate change on snowmelt runoff in Kaidu Watershed, Northwest China. The system couples Hadley Centre Coupled Model version 3 (HadCM3 outputs with Snowmelt Runoff Model (SRM. The SRM was verified against observed discharge for outlet hydrological station of the watershed during the period from April to September in 2001 and generally performed well for Nash-Sutcliffe coefficient (EF and water balance coefficient (RE. The EF is approximately over 0.8, and the water balance error is lower than ± 10%, indicating reasonable prediction accuracy. The Statistical Downscaling Model (SDSM was used to downscale coarse outputs of HadCM3, and then the downscaled future climate data were used as inputs of the SRM. Four scenarios were considered for analyzing the climate change impact on snowmelt flow in the Kaidu Watershed. And the results indicated that watershed hydrology would alter under different climate change scenarios. The stream flow in spring is likely to increase with the increased mean temperature; the discharge and peck flow in summer decrease with the decreased precipitation under Scenarios 1 and 2. Moreover, the consideration of the change in cryosphere area would intensify the variability of stream flow under Scenarios 3 and 4. The modeling results provide useful decision support for water resources management.

  11. Technical-economic feasibility of orbiting sunlight reflectors

    Science.gov (United States)

    Alferov, Z.; Minin, V.

    1986-02-01

    The use of deflectors in orbit as a means of providing artificial illumination is examined. Considerations of technical and economic feasibility are addressed. Three main areas of application are distinguished: reflecting sunlight onto the surface of the Earth; concentration of the flow of solar energy on an orbiting receiver; and retransmission of optical radiation. The advantages of the artificial Earth illumination application of the orbiting reflector scheme in terms of energy savings in lighting cities, and additional daylight time for critical periods of farming operations are discussed.

  12. Interannual Variability in Dust Deposition, Radiative Forcing, and Snowmelt Rates in the Colorado River Basin

    Science.gov (United States)

    Skiles, M.; Painter, T. H.; Deems, J. S.; Barrett, A. P.

    2011-12-01

    Dust in snow accelerates snowmelt through its direct reduction of albedo and its further reduction of albedo by accelerating the growth of snow effective grain size. Since the Anglo expansion and disturbance of the western US that began in the mid 19th century, the mountain snow cover of the Colorado River Basin has been subject to five-fold greater dust loading. Here we present the impacts of dust deposition onto alpine snow cover using a 7-year energy balance record at the alpine and subalpine towers in the Senator Beck Basin Study Area (SBBSA), San Juan Mountains in southwestern Colorado, USA. We assess the radiative and hydrologic impacts with a two-layer point snow energy balance snowmelt model that calculates snowmelt and predicts point runoff using measured inputs of energy exchanges and snow properties. By removing the radiative forcing due to dust, we can determine snowmelt under observed dusty and modeled clean conditions. Additionally, we model the relative response of melt rates to simulated increases in air temperature. Our modeling results indicate that the number of days that dust advances retreat of snow cover and cumulative radiative forcing are linearly related to total dust concentration. The greatest dust radiative impact occurred in 2009, when the highest observed end of year dust concentrations reduced visible albedo to less than 0.35 during the last three weeks of snowcover and snow cover duration was shortened by 50 days. This work also shows that dust radiative forcing has a markedly greater impact on snow cover duration than increases in temperature in terms of acceleration of snowmelt. We have completed the same analysis over a 2-year energy balance record at the Grand Mesa Study plot (GMSP) in west central Colorado, 150 km north of SBBSA. This new location allows us to assess site variability. For example, at SBBSA 2010 and 2011 were the second and third highest dust deposition years, respectively, but 2010 was a larger year with 3

  13. Ocean color remote sensing using polarization properties of reflected sunlight

    Science.gov (United States)

    Frouin, R.; Pouliquen, E.; Breon, F.-M.

    1994-01-01

    The effects of the atmosphere and surface on sunlight backscattered to space by the ocean may be substantially reduced by using the unpolarized component of reflectance instead of total reflectance. At 450 nm, a wavelength of interest in ocean color remote sensing, and for typical conditions, 45% of the unpolarized reflectance may originate from the water body instead of 20% of the total reflectance, which represents a gain of a factor 2.2 in useful signal for water composition retrieval. The best viewing geometries are adjacent to the glitter region; they correspond to scattering angles around 100 deg, but they may change slightly depending on the polarization characteristics of the aerosols. As aerosol optical thickness increases, the atmosphere becomes less efficient at polarizing sunlight, and the enhancement of the water body contribution to unpolarized reflectance is reduced. Since the perturbing effects are smaller on unpolarized reflectance, at least for some viewing geometries, they may be more easily corrected, leading to a more accurate water-leaving signal and, therefore, more accurate estimates of phytoplankton pigment concentration.

  14. Bleaching of the thermoluminescence of feldspars by sunlight

    International Nuclear Information System (INIS)

    Robertson, G.B.; Prescott, J.R.; Hutton, J.T.

    1991-01-01

    Feldspars are an important component of materials used for thermoluminescence (TL) and photoluminescence (PL) dating of sediments; and successful dating implies a knowledge of the degree of re-setting by exposure to sunlight of the stored luminescence energy. We have studied the bleaching by full sunlight of the TL of six alkali feldspars of representative composition and of one oligoclase. The high potassium and high sodium feldspars are the brightest, and are also the least easily bleached, whereas those of intermediate (K-Na) composition bleach quickly. On a time scale of upwards of 16 h, all samples would have bleached enough for them to be useful for TL dating. A search was made for individual glow curve peaks that bleach particularly quickly (and are thus similar to the well-known 325 o C peak used in the TL dating of quartz). In the samples studied, there was only one glow curve peak that was selectively susceptible to bleaching: the 280 o C peak in oligoclase. (author)

  15. Can Skin Exposure to Sunlight Prevent Liver Inflammation?

    Directory of Open Access Journals (Sweden)

    Shelley Gorman

    2015-05-01

    Full Text Available Liver inflammation contributes towards the pathology of non-alcoholic fatty liver disease (NAFLD. Here we discuss how skin exposure to sunlight may suppress liver inflammation and the severity of NAFLD. Following exposure to sunlight-derived ultraviolet radiation (UVR, the skin releases anti-inflammatory mediators such as vitamin D and nitric oxide. Animal modeling studies suggest that exposure to UVR can prevent the development of NAFLD. Association studies also support a negative link between circulating 25-hydroxyvitamin D and NAFLD incidence or severity. Clinical trials are in their infancy and are yet to demonstrate a clear beneficial effect of vitamin D supplementation. There are a number of potentially interdependent mechanisms whereby vitamin D could dampen liver inflammation, by inhibiting hepatocyte apoptosis and liver fibrosis, modulating the gut microbiome and through altered production and transport of bile acids. While there has been a focus on vitamin D, other mediators induced by sun exposure, such as nitric oxide may also play important roles in curtailing liver inflammation.

  16. Detection of the timing and duration of snowmelt in the Hindu Kush-Himalaya using QuikSCAT, 2000-2008

    International Nuclear Information System (INIS)

    Panday, Prajjwal K; Frey, Karen E; Ghimire, Bardan

    2011-01-01

    The Hindu Kush-Himalayan (HKH) region holds the largest mass of ice in Central Asia and is highly vulnerable to global climate change, experiencing significant warming (0.21 ± 0.08 deg. C/decade) over the past few decades. Accurate monitoring of the timing and duration of snowmelt across the HKH region is important, as this region is expected to experience further warming in response to increased greenhouse gas forcing. Despite the many advantages and applications of satellite-derived radar scatterometer data shown for capturing ice and snow melt dynamics at high latitudes, similar comprehensive freeze/thaw detection studies at lower latitudes (including the HKH region) are still absent from the scientific literature. A comprehensive freeze/thaw detection study is utilized on perennial snow/ice and seasonal snow cover for the first time in the Himalayan and Karakoram regions. A dynamic threshold-based method is applied to enhanced QuikSCAT Ku-band backscatter observations from 2000 to 2008 that (a) provides spatial maps of the timing of melt, freeze, and melt season duration, and (b) emphasizes regional variability in freeze/thaw dynamics. The resulting average melt durations for 2000-2008 are 161 ± 11 days (early May-mid-October) for the eastern Himalayas, 130 ± 16 days (late May-early October) for the central Himalayas, 124 ± 13 days (mid-May-mid-September) for the western Himalayas, and 124 ± 12 days (late May-late September) for the Karakoram region. The eastern Himalayan region has on average an earlier melt onset, a later freeze-up, and therefore a longer melt season (∼5 weeks) relative to the central and western Himalayan and the Karakoram regions. Snowmelt dynamics exhibit regional and interannual variability with clear connections to terrain features, in particular elevation and aspect. With respect to ongoing controversies surrounding melt in the Himalayan region, this study provides an overall perspective of regional differences in melt onset

  17. Detection of the timing and duration of snowmelt in the Hindu Kush-Himalaya using QuikSCAT, 2000-2008

    Energy Technology Data Exchange (ETDEWEB)

    Panday, Prajjwal K; Frey, Karen E; Ghimire, Bardan, E-mail: ppanday@clarku.edu [Graduate School of Geography, Clark University, 950 Main Street, Worcester, MA 01610 (United States)

    2011-04-15

    The Hindu Kush-Himalayan (HKH) region holds the largest mass of ice in Central Asia and is highly vulnerable to global climate change, experiencing significant warming (0.21 {+-} 0.08 deg. C/decade) over the past few decades. Accurate monitoring of the timing and duration of snowmelt across the HKH region is important, as this region is expected to experience further warming in response to increased greenhouse gas forcing. Despite the many advantages and applications of satellite-derived radar scatterometer data shown for capturing ice and snow melt dynamics at high latitudes, similar comprehensive freeze/thaw detection studies at lower latitudes (including the HKH region) are still absent from the scientific literature. A comprehensive freeze/thaw detection study is utilized on perennial snow/ice and seasonal snow cover for the first time in the Himalayan and Karakoram regions. A dynamic threshold-based method is applied to enhanced QuikSCAT Ku-band backscatter observations from 2000 to 2008 that (a) provides spatial maps of the timing of melt, freeze, and melt season duration, and (b) emphasizes regional variability in freeze/thaw dynamics. The resulting average melt durations for 2000-2008 are 161 {+-} 11 days (early May-mid-October) for the eastern Himalayas, 130 {+-} 16 days (late May-early October) for the central Himalayas, 124 {+-} 13 days (mid-May-mid-September) for the western Himalayas, and 124 {+-} 12 days (late May-late September) for the Karakoram region. The eastern Himalayan region has on average an earlier melt onset, a later freeze-up, and therefore a longer melt season ({approx}5 weeks) relative to the central and western Himalayan and the Karakoram regions. Snowmelt dynamics exhibit regional and interannual variability with clear connections to terrain features, in particular elevation and aspect. With respect to ongoing controversies surrounding melt in the Himalayan region, this study provides an overall perspective of regional differences in

  18. A generic approach for sunlight and shadow impact computation on large city models

    OpenAIRE

    Jaillot , Vincent; Pedrinis , Frédéric; Servigne , Sylvie; Gesquière , Gilles

    2017-01-01

    International audience; Study of sunlight and shadow effects on the city has become more accessible with the development of 3D citymodels. It allows measuring when and how an object is exposed to the sunlight, which enables conducting manyrelated studies such as energy analyses or urban planning. While many works have been done for this purpose, itmay be interesting to know which objects (terrain, buildings, trees, etc.) prevent other objects from beingexposed to the sunlight. In this paper w...

  19. Early snowmelt events: detection, distribution, and significance in a major sub-arctic watershed

    International Nuclear Information System (INIS)

    Semmens, Kathryn Alese; Ramage, Joan; Bartsch, Annett; Liston, Glen E

    2013-01-01

    High latitude drainage basins are experiencing higher average temperatures, earlier snowmelt onset in spring, and an increase in rain on snow (ROS) events in winter, trends that climate models project into the future. Snowmelt-dominated basins are most sensitive to winter temperature increases that influence the frequency of ROS events and the timing and duration of snowmelt, resulting in changes to spring runoff. Of specific interest in this study are early melt events that occur in late winter preceding melt onset in the spring. The study focuses on satellite determination and characterization of these early melt events using the Yukon River Basin (Canada/USA) as a test domain. The timing of these events was estimated using data from passive (Advanced Microwave Scanning Radiometer—EOS (AMSR-E)) and active (SeaWinds on Quick Scatterometer (QuikSCAT)) microwave remote sensors, employing detection algorithms for brightness temperature (AMSR-E) and radar backscatter (QuikSCAT). The satellite detected events were validated with ground station meteorological and hydrological data, and the spatial and temporal variability of the events across the entire river basin was characterized. Possible causative factors for the detected events, including ROS, fog, and positive air temperatures, were determined by comparing the timing of the events to parameters from SnowModel and National Centers for Environmental Prediction North American Regional Reanalysis (NARR) outputs, and weather station data. All melt events coincided with above freezing temperatures, while a limited number corresponded to ROS (determined from SnowModel and ground data) and a majority to fog occurrence (determined from NARR). The results underscore the significant influence that warm air intrusions have on melt in some areas and demonstrate the large temporal and spatial variability over years and regions. The study provides a method for melt detection and a baseline from which to assess future change

  20. Ultraviolet- and sunlight-induced lipid peroxidation in liposomal membrane

    International Nuclear Information System (INIS)

    Mandal, T.K.; Chatterjee, S.N.

    1980-01-01

    Ultraviolet radiation and sunlight caused lipid peroxidation in the liposomal membrane (as detected by measurement of the oxidation index, A 233 /A 215 , and the amount of malondialdehyde formed) and made the membrane leaky (as revealed by the release of the trapped chromate anions). The oxidation index and the formation of malondialdehyde increased linearly with increasing dose of radiation and depended significantly on the dose rate. The effects were smaller in liposomes derived from Vibrio cholerae phospholipid than in those derived from egg lecithin. The effects of the radiation dose and dose rate on hemolysis and peroxidation (MDA formation) of the erythrocyte membrane followed a similar pattern. A direct correlation between the percentage leakage of chromate (Y) and the oxidation index (X) of the liposomal system was obtained as Y = 236.5 x X

  1. Harvesting Water from Air: Using Anhydrous Salt with Sunlight

    KAUST Repository

    Li, Renyuan

    2018-04-02

    Atmospheric water is abundant alternative water resource, equivalent to 6 times of water in all rivers on Earth. This work screens 14 common anhydrous and hydrated salt couples in terms of their physical and chemical stability, water vapor harvesting and release capacity under relevant application scenarios. Among the salts screened, copper chloride (CuCl2), copper sulfate (CuSO4) and magnesium sulfate (MgSO4) distinguish themselves and are further made into bi-layer water collection devices, with the top layer being photothermal layer while the bottom layer being salt-loaded fibrous membrane. The water collection devices are capable of capturing water vapor out of the air with low relative humidity (down to 15 %) and releasing water under regular and even weakened sunlight (i.e. 0.7 kW/m2). The work shines light on the potential use of anhydrous salt towards producing drinking water in water scarce regions.

  2. Persistence of Bacteroides ovatus under simulated sunlight irradiation

    KAUST Repository

    Dong, Shengkun

    2014-07-04

    Background: Bacteroides ovatus, a member of the genus Bacteroides, is considered for use in molecular-based methods as a general fecal indicator. However, knowledge on its fate and persistence after a fecal contamination event remains limited. In this study, the persistence of B. ovatus was evaluated under simulated sunlight exposure and in conditions similar to freshwater and seawater. By combining propidium monoazide (PMA) treatment and quantitative polymerase chain reaction (qPCR) detection, the decay rates of B. ovatus were determined in the presence and absence of exogenous photosensitizers and in salinity up to 39.5 parts per thousand at 27°C. Results: UVB was found to be important for B. ovatus decay, averaging a 4 log10 of decay over 6 h of exposure without the presence of extracellular photosensitizers. The addition of NaNO2, an exogenous sensitizer producing hydroxyl radicals, did not significantly change the decay rate of B. ovatus in both low and high salinity water, while the exogenous sensitizer algae organic matter (AOM) slowed down the decay of B. ovatus in low salinity water. At seawater salinity, the decay rate of B. ovatus was slower than that in low salinity water, except when both NaNO2 and AOM were present. Conclusion: The results of laboratory experiments suggest that if B. ovatus is released into either freshwater or seawater environment in the evening, 50% of it may be intact by the next morning; if it is released at noon, only 50% may be intact after a mere 5 min of full spectrum irradiation on a clear day. This study provides a mechanistic understanding to some of the important environmental relevant factors that influenced the inactivation kinetics of B. ovatus in the presence of sunlight irradiation, and would facilitate the use of B. ovatus to indicate the occurrence of fecal contamination.

  3. Using 87Sr/86Sr ratios to investigate changes in stream chemistry during snowmelt in the Provo River, Utah, USA

    Science.gov (United States)

    Hale, C. A.; Carling, G. T.; Fernandez, D. P.; Nelson, S.; Aanderud, Z.; Tingey, D. G.; Dastrup, D.

    2017-12-01

    Water chemistry in mountain streams is variable during spring snowmelt as shallow groundwater flow paths are activated in the watershed, introducing solutes derived from soil water. Sr isotopes and other tracers can be used to differentiate waters that have interacted with soils and dust (shallow groundwater) and bedrock (deep groundwater). To investigate processes controlling water chemistry during snowmelt, we analyzed 87Sr/86Sr ratios, Sr and other trace element concentrations in bulk snowpack, dust, soil, soil water, ephemeral channels, and river water during snowmelt runoff in the upper Provo River watershed in northern Utah, USA, over four years (2014-2017). Strontium concentrations in the river averaged 20 ppb during base flow and decreased to 10 ppb during snowmelt runoff. 87Sr/86Sr ratios were around 0.717 during base flow and decreased to 0.715 in 2014 and 0.713 in 2015 and 2016 during snowmelt, trending towards less radiogenic values of mineral dust inputs in the Uinta Mountain soils. Ephemeral channels, representing shallow flow paths with soil water inputs, had Sr concentrations between 7-20 ppb and 87Sr/86Sr ratios between 0.713-0.716. Snowpack Sr concentrations were generally soils that contain accumulated dust deposits with a less radiogenic 87Sr/86Sr ratio. These results suggest that flow paths and atmospheric dust are important to consider when investigating variable solute loads in mountain streams.

  4. [Simulation of rainfall and snowmelt runoff reduction in a northern city based on combination of green ecological strategies.

    Science.gov (United States)

    Han, Jin Feng; Liu, Shuo; Dai, Jun; Qiu, Hao

    2018-02-01

    With the aim to control and reduce rainfall and snowmelt runoff in northern cities in China, the summer runoff and spring snowmelt runoff in the studied area were simulated with the establishment of storm water management model (SWMM). According to the climate characteristics and the situation of the studied area, the low impact development (LID) green ecological strategies suitable for the studied area were established. There were three kinds of management strategies being used, including extended green roof, snow and rainwater harvesting devices, and grass-swales or trenches. We examined the impacts of those integrated green ecological measures on the summer rainfall and spring snowmelt runoff and their mitigation effects on the drainage network pressure. The results showed that the maximum flow rates of the measured rainfall in May 24th, June 10th and July 18th 2016 were 2.7, 6.2 and 7.4 m 3 ·s -1 respectively. The peak flow rates at different return periods of 1, 2, 5, 10 years were 2.39, 3.91, 6.24 and 7.85 m 3 ·s -1 , respectively. In the snowmelt period, the peak flow appeared at the beginning of March. The LID measures had positive effect on peak flow reduction, and thus delayed peak time and relieved drainage pressure. The flow reduction rate was as high as 70%. Moreover, the snow harvesting devices played a positive role in controlling snowmelt runoff in spring.

  5. Snow Cover, Snowmelt Timing and Stream Power in the Wind River Range, Wyoming

    Science.gov (United States)

    Hall, Dorothy K.; Foster, James L.; DiGirolamo, Nicolo E.; Riggs, George A.

    2011-01-01

    Earlier onset of springtime weather, including earlier snowmelt, has been documented in the western United States over at least the last 50 years. Because the majority (is greater than 70%) of the water supply in the western U.S. comes from snowmelt, analysis of the declining spring snowpack (and shrinking glaciers) has important implications for the management of streamflow. The amount of water in a snowpack influences stream discharge which can also influence erosion and sediment transport by changing stream power, or the rate at which a stream can do work, such as move sediment and erode the stream bed. The focus of this work is the Wind River Range (WRR) in west-central Wyoming. Ten years of Moderate-Resolution Imaging Spectroradiometer (MODIS) snow-cover, cloud-gap-filled (CGF) map products and 30 years of discharge and meteorological station data are studied. Streamflow data from streams in WRR drainage basins show lower annual discharge and earlier snowmelt in the decade of the 2000s than in the previous three decades, though no trend of either lower streamflow or earlier snowmelt was observed within the decade of the 2000s. Results show a statistically-significant trend at the 95% confidence level (or higher) of increasing weekly maximum air temperature (for three out of the five meteorological stations studied) in the decade of the 1970s, and also for the 40-year study period as a whole. The extent of snow-cover (percent of basin covered) derived from the lowest elevation zone (2500-3000 m) of the WRR, using MODIS CGF snow-cover maps, is strongly correlated with maximum monthly discharge on 30 April, where Spearman's Rank correlation, rs,=0.89 for the decade of the 2000s. We also investigated stream power for Bull Lake Creek above Bull Lake; and found a trend (significant at the 90% confidence level) toward reduced stream power from 1970 to 2009. Observed changes in streamflow and stream power may be related to increasing weekly maximum air temperature

  6. Phenology and carbon dioxide source/sink strength of a subalpine grassland in response to an exceptionally short snow season

    International Nuclear Information System (INIS)

    Galvagno, M; Cremonese, E; Filippa, G; Morra di Cella, U; Wohlfahrt, G; Rossini, M; Colombo, R; Julitta, T; Manca, G; Siniscalco, C; Migliavacca, M

    2013-01-01

    Changes in snow cover depth and duration predicted by climate change scenarios are expected to strongly affect high-altitude ecosystem processes. This study investigates the effect of an exceptionally short snow season on the phenology and carbon dioxide source/sink strength of a subalpine grassland. An earlier snowmelt of more than one month caused a considerable advancement (40 days) of the beginning of the carbon uptake period (CUP) and, together with a delayed establishment of the snow season in autumn, contributed to a two-month longer CUP. The combined effect of the shorter snow season and the extended CUP led to an increase of about 100% in annual carbon net uptake. Nevertheless, the unusual environmental conditions imposed by the early snowmelt led to changes in canopy structure and functioning, with a reduction of the carbon sequestration rate during the snow-free period. (letter)

  7. PRKCZ methylation is associated with sunlight exposure in a North American but not a Mediterranean population

    Science.gov (United States)

    Sunlight exposure has been shown to alter DNA methylation patterns across several human cell-types, including T-lymphocytes. Since epigenetic changes establish gene expression profiles, changes in DNA methylation induced by sunlight exposure warrant investigation. The purpose of this study was to as...

  8. Sunlight exposure and sun sensitivity associated with disability progression in multiple sclerosis

    NARCIS (Netherlands)

    D'hooghe, M. B.; Haentjens, P.; Nagels, G.; Garmyn, M.; De Keyser, J.

    Background: Sunlight and vitamin D have been inversely associated with the risk of multiple sclerosis (MS). Objective: We investigated sunlight exposure and sun sensitivity in relation to disability progression in MS. Methods: We conducted a survey among persons with MS, registered by the Flemish MS

  9. Integration of aspect and slope in snowmelt runoff modeling in a mountain watershed

    Directory of Open Access Journals (Sweden)

    Shalamu Abudu

    2016-10-01

    Full Text Available This study assessed the performances of the traditional temperature-index snowmelt runoff model (SRM and an SRM model with a finer zonation based on aspect and slope (SRM + AS model in a data-scarce mountain watershed in the Urumqi River Basin, in Northwest China. The proposed SRM + AS model was used to estimate the melt rate with the degree-day factor (DDF through the division of watershed elevation zones based on aspect and slope. The simulation results of the SRM + AS model were compared with those of the traditional SRM model to identify the improvements of the SRM + AS model's performance with consideration of topographic features of the watershed. The results show that the performance of the SRM + AS model has improved slightly compared to that of the SRM model. The coefficients of determination increased from 0.73, 0.69, and 0.79 with the SRM model to 0.76, 0.76, and 0.81 with the SRM + AS model during the simulation and validation periods in 2005, 2006, and 2007, respectively. The proposed SRM + AS model that considers aspect and slope can improve the accuracy of snowmelt runoff simulation compared to the traditional SRM model in mountain watersheds in arid regions by proper parameterization, careful input data selection, and data preparation.

  10. Snowmelt runoff in the Green River basin derived from MODIS snow extent

    Science.gov (United States)

    Barton, J. S.; Hall, D. K.

    2011-12-01

    The Green River represents a vital water supply for southwestern Wyoming, northern Colorado, eastern Utah, and the Lower Colorado River Compact states (Arizona, Nevada, and California). Rapid development in the southwestern United States combined with the recent drought has greatly stressed the water supply of the Colorado River system, and concurrently increased the interest in long-term variations in stream flow. Modeling of snowmelt runoff represents a means to predict flows and reservoir storage, which is useful for water resource planning. An investigation is made into the accuracy of the Snowmelt Runoff Model of Martinec and Rango, driven by Moderate Resolution Imaging Spectroradiometer (MODIS) snow maps for predicting stream flow within the Green River basin. While the moderate resolution of the MODIS snow maps limits the spatial detail that can be captured, the daily coverage is an important advantage of the MODIS imagery. The daily MODIS snow extent is measured using the most recent clear observation for each 500-meter pixel. Auxiliary data used include temperature and precipitation time series from the Snow Telemetry (SNOTEL) and Remote Automated Weather Station (RAWS) networks as well as from National Weather Service records. Also from the SNOTEL network, snow-water equivalence data are obtained to calibrate the conversion between snow extent and runoff potential.

  11. The role of environmental parameter (degree day of snowmelt runoff simulation

    Directory of Open Access Journals (Sweden)

    Ghulam Nabi*, Muhammad Latif, Habib-ur-Rehman and Aftab Hussain Azhar

    2011-04-01

    Full Text Available The upper Indus basin comprises the high mountains covered with snow and glaciers. So the major portion of flowfrom Indus basin is due to snow and glacier melt runoff. The terrain is difficult to measure the hydrological andhydraulics data. Most of the data is available at catchments outlets. Due to the data constraints Snowmelt RunoffModel (SRM was used to estimate the snow melt runoff in Astor basin during, year 2000. The input data includeddaily temperature, precipitation and division of catchment in to different zones on the basis of elevation difference.The elevation zones were made from the Digital Elevation Model (DEM of the area. The snow depletion curveswere made by Landsat TM satellite data analysis on the monthly basis. The model output was dischargehydrograph. The model performance was tested by calculating the statistical parameters such as coefficient ofefficiency (COE and volume difference in percentage. The COE for simulation was 0.91 which illustrates a goodrelationship between simulated and measured values of runoff. The volume difference (Dv for simulation was 9.01.The statistical test showed that model performance was good. The results of SRM model encouraged to usetemperature index approach for snowmelt runoff estimation in Indus basin.

  12. Investigation of sunlight-induced deterioration of aroma of pummelo (Citrus maxima) essential oil.

    Science.gov (United States)

    Sun, Hao; Ni, Hui; Yang, Yuanfan; Wu, Ling; Cai, Hui-nong; Xiao, An-feng; Chen, Feng

    2014-12-10

    Deterioration of aromas of pummelo essential oil (EO) induced by sunlight was compared to those induced by heat and oxygen exposure using the techniques of sensory evaluation and GC-MS analysis. The sunlight-exposed EO was found to possess an oily off-flavor odor, which was significantly different from its counterparts induced by oxygen and heat. The strong oily note of the sunlight-exposed EO was attributed to the existence of linalool oxides and limonene oxides, as well as the lack of neral and geranial, for which UV sunlight was revealed to be the critical contributor causing the chemical reactions for the aroma changes. The results demonstrated that UV sunlight could significantly affect the aroma of the pummelo EO, providing valuable information that will benefit the production and storage of EO-based aromatic products.

  13. Asteroid thermal modeling in the presence of reflected sunlight

    Science.gov (United States)

    Myhrvold, Nathan

    2018-03-01

    A new derivation of simple asteroid thermal models is presented, investigating the need to account correctly for Kirchhoff's law of thermal radiation when IR observations contain substantial reflected sunlight. The framework applies to both the NEATM and related thermal models. A new parameterization of these models eliminates the dependence of thermal modeling on visible absolute magnitude H, which is not always available. Monte Carlo simulations are used to assess the potential impact of violating Kirchhoff's law on estimates of physical parameters such as diameter and IR albedo, with an emphasis on NEOWISE results. The NEOWISE papers use ten different models, applied to 12 different combinations of WISE data bands, in 47 different combinations. The most prevalent combinations are simulated and the accuracy of diameter estimates is found to be depend critically on the model and data band combination. In the best case of full thermal modeling of all four band the errors in an idealized model the 1σ (68.27%) confidence interval is -5% to +6%, but this combination is just 1.9% of NEOWISE results. Other combinations representing 42% of the NEOWISE results have about twice the CI at -10% to +12%, before accounting for errors due to irregular shape or other real world effects that are not simulated. The model and data band combinations found for the majority of NEOWISE results have much larger systematic and random errors. Kirchhoff's law violation by NEOWISE models leads to errors in estimation accuracy that are strongest for asteroids with W1, W2 band emissivity ɛ12 in both the lowest (0.605 ≤ɛ12 ≤ 0 . 780), and highest decile (0.969 ≤ɛ12 ≤ 0 . 988), corresponding to the highest and lowest deciles of near-IR albedo pIR. Systematic accuracy error between deciles ranges from a low of 5% to as much as 45%, and there are also differences in the random errors. Kirchhoff's law effects also produce large errors in NEOWISE estimates of pIR, particularly for high

  14. Genotoxic action of sunlight upon Bacillus subtilis spores

    International Nuclear Information System (INIS)

    Munakata, Nobuo

    1989-01-01

    Samples of Bacillus subtilis spores dried on membrane filter were exposed to natural sunlight from solar-noon time at Tokyo. The survival and mutation induction of wild-type (UVR) and repair-deficient (UVS) spores were determined on 66 occasions since 1979. Two of the values were considered to be useful in monitoring solar UV intensity; the inverse of the time (in minutes) of exposure to kill 63% of the UVS spores ('sporocidal index') and the induced mutation frequency at 60 minutes of exposure of the UVR spores ('mutagenic index'). Both values were varied greatly due to time of a year, weather and other conditions. Estimates of year-round changes under clear skies were obtained by connecting the maximum values attained in these years. In these curves, there are more than 7-fold differences in the genotoxicity between winter and summer months, with major increases observed in early spring and decreases through autumn. Using a series of UV cut-off filters, the wavelengths most effective for the sporocidal actions were estimated to be in the range of 308 - 325 nm, shorter wavelengths being effective when the genotoxicity was higher. Sunburn meter of Robertson-Berger type seems to respond to slightly longer wavelength components of the solar spectrum. However, a reasonable correlation was obtained between the reading of the meter and the sporocidal index. (author)

  15. The economic feasibility of producing hydrogen from sunlight and wind

    International Nuclear Information System (INIS)

    Mann, M. K.; Spath, P. L.; Watt, A. S.

    1999-01-01

    The feasibility of utilizing photoelectrochemical and electrolytical technologies to convert energy from the sun and wind into hydrogen was studied. In exploring opportunities to reduce the cost of hydrogen production through interaction with the electric utility grid, it was found that direct photoelectrochemical (PEC) conversion of sunlight has the economic potential to compete with direct photovoltaic/electrolysis, notwithstanding the significant stability and efficiency issues that are still awaiting solution. Interaction with the grid, while maximizing electrolizer use, makes a significant impact on the economics of producing hydrogen by photovoltaic/electrolysis, making wind-based systems also more economical. Electrolysis was found to be the optimal solution only with electricity from renewable sources or with less expensive non-peak electricity. On the other hand, the delivered cost of hydrogen was found to the lowest when electricity production was decoupled from the hydrogen production operation. Decoupled hydrogen production also has an additional benefit, i.e. it produces the hydrogen where it is needed, therefore it mitigates the need for various storage and distribution costs. 6 refs., 4 tabs., 2 figs

  16. Theory of direct sunlight transmission through orthogonal screen cells

    International Nuclear Information System (INIS)

    Aljofi, E.K.

    2006-01-01

    The Purpose of this paper is to investigate the feasibility of using the Rawshan screens to control high light intensity and to avoid excessive solar radiation penetrating inside the building interior. The exploration of the environmental characteristics of this device indicates an ideal solution to utilize available daylight in the arid atmosphere, reduces energy consumption due to the us of artificial light and ensures the continuity of the traditional architecture and the country heritage. A systematic analysis of direct sunlight transmission has been explored using a mathematical approach. The study intends to construct a predictive tool for the architects through which different specifications of the Rawshan screens were identified as far as direct beam of light concerned. The predictive tool was set-up to investigate various parameters of the screen such as the screen configurations, the aperture configurations, the change in orientation and the effect of the sky condition. The analysis of light transmission through the screen were set-up for orthogonal shapes

  17. Dust in Snow in the Colorado River Basin: Spatial Variability in Dust Concentrations, Radiative Forcing, and Snowmelt Rates

    Science.gov (United States)

    Skiles, M.; Painter, T.; Deems, J. S.; Landry, C.; Bryant, A.

    2012-12-01

    Since the disturbance of the western US that began with the Anglo settlement in the mid 19th century, the mountain snow cover of the Colorado River Basin (CRB) has been subject to five-fold greater dust loading. This dust deposition accelerates snowmelt through its direct reduction of albedo and its further reduction of albedo by accelerating the growth of snow effective grain size. We have previously quantified the impacts of dust in snow using a 6-year record of dust concentration and energy balance fluxes at the alpine and subalpine towers in the Senator Beck Basin Study Area (SBBSA), San Juan Mountains in southwestern Colorado, USA. Dust loading exhibited interannual variability, and end of year dust concentrations were not necessarily related to the number of dust deposition events. Radiative forcing enhanced springtime melt by 21 to 51 days with the magnitude of advanced loss being linearly related to total dust concentration at the end of snow cover. To expand our understanding of dust on snow deposition patterns we utilize collections of dust concentration at the Colorado Dust on Snow (CODOS) study sites, established in 2009 along the western side of the CRB, to assess spatial variability in dust loading. In situ sampling of dust stratigraphy and concentration occurs twice each season, once over peak snow water equivalent (15 April), and again during melt (15 May). Dust loading occurs at all sites; dust concentrations are always higher in May, vary between sites, and the highest and lowest dust years were 2009 and 2012, respectively. In the absence of regular sampling and energy balance instrumentation these sites do not allow us to quantify the advanced melt due to dust. To facilitate this a new energy balance site, Grand Mesa Study plot (GMSP), was established for water year 2010 in west central Colorado, 150 km north of SBBSA. Back trajectories indicate similar Colorado Plateau dust sources at both SBBSA and GMSP, yet GMSP exhibits slightly lower dust

  18. Monitoring of the Liquid Water Content During Snowmelt Using C-Band SAR Data and the Snow Model CROCUS

    Science.gov (United States)

    Rondeau-Genesse, G.; Trudel, M.; Leconte, R.

    2014-12-01

    Coupling C-Band synthetic aperture radar (SAR) data to a multilayer snow model is a step in better understanding the temporal evolution of the radar backscattering coefficient during snowmelt. The watershed used for this study is the Nechako River Basin, located in the Rocky Mountains of British-Columbia (Canada). This basin has a snowpack of several meters in depth and part of its water is diverted to the Kemano hydropower system, managed by Rio-Tinto Alcan. Eighteen RADARSAT-2 ScanSAR Wide archive images were acquired in VV/VH polarization for the winter of 2011-2012, under different snow conditions. They are interpreted along with CROCUS, a multilayer physically-based snow model developed by Météo-France. This model discretizes the snowpack into 50 layers, which makes it possible to monitor various characteristics, such as liquid water content (LWC), throughout the season. CROCUS is used to model three specific locations of the Nechako River Basin. Results vary from one site to another, but in general there is a good agreement between the modeled LWC of the first layer of the snowpack and the backscattering coefficient of the RADARSAT-2 images, with a coefficient of determination (R²) of 0.80 and more. The radar images themselves were processed using an updated version of Nagler's methodology, which consists of subtracting an image in wet snow conditions to one in dry snow conditions, as wet snow can then be identified using a soft threshold centered around -3 dB. A second filter was used in order to differentiate dry snow and bare soil. That filter combines a VH/VV ratio threshold and an altitude criterion. The ensuing maps show a good agreement with the MODIS snow-covered area, which is already obtained daily over the Nechako River Basin, but with additional information on the location of wet snow and without sensibility to cloud cover. As a next step, the outputs of CROCUS will be used in Mätzler's Microwave Emission Model of Layered Snowpacks (MEMLS) to

  19. High resolution climate scenarios for snowmelt modelling in small alpine catchments

    Science.gov (United States)

    Schirmer, M.; Peleg, N.; Burlando, P.; Jonas, T.

    2017-12-01

    Snow in the Alps is affected by climate change with regard to duration, timing and amount. This has implications with respect to important societal issues as drinking water supply or hydropower generation. In Switzerland, the latter received a lot of attention following the political decision to phase out of nuclear electricity production. An increasing number of authorization requests for small hydropower plants located in small alpine catchments was observed in the recent years. This situation generates ecological conflicts, while the expected climate change poses a threat to water availability thus putting at risk investments in such hydropower plants. Reliable high-resolution climate scenarios are thus required, which account for small-scale processes to achieve realistic predictions of snowmelt runoff and its variability in small alpine catchments. We therefore used a novel model chain by coupling a stochastic 2-dimensional weather generator (AWE-GEN-2d) with a state-of-the-art energy balance snow cover model (FSM). AWE-GEN-2d was applied to generate ensembles of climate variables at very fine temporal and spatial resolution, thus providing all climatic input variables required for the energy balance modelling. The land-surface model FSM was used to describe spatially variable snow cover accumulation and melt processes. The FSM was refined to allow applications at very high spatial resolution by specifically accounting for small-scale processes, such as a subgrid-parametrization of snow covered area or an improved representation of forest-snow processes. For the present study, the model chain was tested for current climate conditions using extensive observational dataset of different spatial and temporal coverage. Small-scale spatial processes such as elevation gradients or aspect differences in the snow distribution were evaluated using airborne LiDAR data. 40-year of monitoring data for snow water equivalent, snowmelt and snow-covered area for entire

  20. Variable flushing mechanisms and landscape structure control stream DOC export during snowmelt in a set of nested catchments

    Science.gov (United States)

    Vincent J. Pacific; Kelsey G. Jencso; Brian L. McGlynn

    2010-01-01

    Stream DOC dynamics during snowmelt have been the focus of much research, and numerous DOC mobilization and delivery mechanisms from riparian and upland areas have been proposed. However, landscape structure controls on DOC export from riparian and upland landscape elements remains poorly understood. We investigated stream and groundwater DOC dynamics across three...

  1. Interannual variability of plant phenology in tussock tundra: modelling interactions of plant productivity, plant phenology, snowmelt and soil thaw

    NARCIS (Netherlands)

    Wijk, van M.T.; Williams, M.; Laundre, J.A.; Shaver, G.R.

    2003-01-01

    We present a linked model of plant productivity, plant phenology, snowmelt and soil thaw in order to estimate interannual variability of arctic plant phenology and its effects on plant productivity. The model is tested using 8 years of soil temperature data, and three years of bud break data of

  2. Potential for western US seasonal snowpack prediction

    Science.gov (United States)

    Kapnick, Sarah B.; Yang, Xiaosong; Vecchi, Gabriel A.; Delworth, Thomas L.; Gudgel, Rich; Malyshev, Sergey; Milly, Paul C. D.; Shevliakova, Elena; Underwood, Seth; Margulis, Steven A.

    2018-01-01

    Western US snowpack—snow that accumulates on the ground in the mountains—plays a critical role in regional hydroclimate and water supply, with 80% of snowmelt runoff being used for agriculture. While climate projections provide estimates of snowpack loss by the end of th ecentury and weather forecasts provide predictions of weather conditions out to 2 weeks, less progress has been made for snow predictions at seasonal timescales (months to 2 years), crucial for regional agricultural decisions (e.g., plant choice and quantity). Seasonal predictions with climate models first took the form of El Niño predictions 3 decades ago, with hydroclimate predictions emerging more recently. While the field has been focused on single-season predictions (3 months or less), we are now poised to advance our predictions beyond this timeframe. Utilizing observations, climate indices, and a suite of global climate models, we demonstrate the feasibility of seasonal snowpack predictions and quantify the limits of predictive skill 8 month sin advance. This physically based dynamic system outperforms observation-based statistical predictions made on July 1 for March snowpack everywhere except the southern Sierra Nevada, a region where prediction skill is nonexistent for every predictor presently tested. Additionally, in the absence of externally forced negative trends in snowpack, narrow maritime mountain ranges with high hydroclimate variability pose a challenge for seasonal prediction in our present system; natural snowpack variability may inherently be unpredictable at this timescale. This work highlights present prediction system successes and gives cause for optimism for developing seasonal predictions for societal needs.

  3. A hydrometric and geochemical approach to test the transmissivity feedback hypothesis during snowmelt

    Science.gov (United States)

    Kendall, K.A.; Shanley, J.B.; McDonnell, Jeffery J.

    1999-01-01

    To test the transmissivity feedback hypothesis of runoff generation, surface and subsurface waters were monitored and sampled during the 1996 snowmelt at various topographic positions in a 41 ha forested headwater catchment at Sleepers River, Vermont. Two conditions that promote transmissivity feedback existed in the catchment during the melt period. First, saturated hydraulic conductivity increased toward land surface, from a geometric mean of 3.6 mm h-1 in glacial till to 25.6 mm h-1 in deep soil to 54.0 mm h-1 in shallow soil. Second, groundwater levels rose to within 0.3 m of land surface at all riparian sites and most hillslope sites at peak melt. The importance of transmissivity feedback to streamflow generation was tested at the catchment scale by examination of physical and chemical patterns of groundwater in near-stream (discharge) and hillslope (recharge/lateral flow) zones, and within a geomorphic hollow (convergent flow). The presence of transmissivity feedback was supported by the abrupt increase in streamflow as the water table rose into the surficial, transmissive zone; a flattening of the groundwater level vs. streamflow curve occurred at most sites. This relation had a clockwise hysteresis (higher groundwater level for given discharge on rising limb than at same discharge on falling limb) at riparian sites, suggesting that the riparian zone was the dominant source area during the rising limb of the melt hydrograph. Hysteresis was counterclockwise at hillslope sites, suggesting that hillslope drainage controlled the snowmelt recession. End member mixing analysis using Ca, Mg, Na, dissolved organic carbon (DOC), and Si showed that stream chemistry could be explained as a two-component mixture of groundwater high in base cations and an O-horizon/overland flow water high in DOC. The dominance of shallow flow paths during events was indicated by the high positive correlation of DOC with streamflow (r2 = 0.82). Despite the occurrence of transmissivity

  4. Biological Effects of Sunlight, Ultraviolet Radiation, Visible Light, Infrared Radiation and Vitamin D for Health.

    Science.gov (United States)

    Holick, Michael F

    2016-03-01

    Humans evolved in sunlight and had depended on sunlight for its life giving properties that was appreciated by our early ancestors. However, for more than 40 years the lay press and various medical and dermatology associations have denounced sun exposure because of its association with increased risk for skin cancer. The goal of this review is to put into perspective the many health benefits that have been associated with exposure to sunlight, ultraviolet A (UVA) ultraviolet B (UVB), visible and infrared radiation. Copyright© 2016 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

  5. Flow and discharge of groundwater from a snowmelt-affected sandy beach

    Science.gov (United States)

    Chaillou, G.; Lemay-Borduas, F.; Larocque, M.; Couturier, M.; Biehler, A.; Tommi-Morin, G.

    2018-02-01

    The study is based on a complex and unique data set of water stable isotopes (i.e., δ18O and δ2H), radon-222 activities (i.e., 222Rn) and groundwater levels to better understand the interaction of fresh groundwater and recirculated seawater in a snowmelt-affected subterranean estuary (STE) in a boreal region (Îles-de-la-Madeleine, Qc, Canada). By using a combination of hydrogeological and marine geochemical approaches, the objective was to analyze and quantify submarine groundwater discharge processes through a boreal beach after the snow melt period, in early June. The distribution of δ18O and δ2H in beach groundwater showed that inland fresh groundwater contributed between 97 and 30% of water masses presented within the STE. A time series of water table levels during the 16 days of the study indicated that tides propagated as a dynamic wave limiting the mass displacement of seawater within the STE. This up-and-down movement of the water table (∼10-30 cm) induced the vertical infiltration of seawater at the falling tide. At the front of the beach, a radon-based mass balance calculated with high-resolution 222Rn survey estimated total SGD of 3.1 m3/m/d at the discharge zone and a mean flow to 1.5 m3/m/d in the bay. The nearshore discharge agreed relatively well with Darcy fluxes calculated at the beach face. Fresh groundwater makes up more than 50% of the total discharge during the measuring campaign. These results indicate that beaches in boreal and cold regions could be important sources of freshwater originate and groundwater-borne solutes and contaminants to the marine environment after the snowmelt.

  6. Spatial patterns of goose grubbing suggest elevated grubbing in dry habitats linked to early snowmelt

    Directory of Open Access Journals (Sweden)

    Åshild Ø. Pedersen

    2013-05-01

    Full Text Available The western Palaearctic tundra is a breeding habitat for large populations of European geese. After their arrival in spring, pink-footed geese (Anser brachyrhynchus forage extensively on below-ground plant parts, using a feeding technique called grubbing that has substantial impact on the tundra vegetation. Previous studies have shown a high frequency of grubbing in lowland fen vegetation. In the present study, we examined the occurrence of grubbing in other habitat types on Spitsbergen, in the Arctic archipelago of Svalbard. Goose grubbing was surveyed along 19 altitudinal transects, going from the valley bottom to altitudes dominated by scree. Grubbing was more frequent in the wet habitat type at low altitudes compared to the drier habitat type at higher altitudes. For the dry habitat type, a higher frequency of grubbing was found in study plots with a south-east facing exposure where snowmelt is expected to be early. This suggests that pink-footed geese primarily use dry vegetation types for grubbing when they are snow-free in early spring and the availability of snow-free patches of the preferred wet vegetation types in the lowlands is limited. Dry vegetation types have poorer recovery rates from disturbance than wet ones. Sites with early snowmelt and dry vegetation types may therefore be at greater risk of long-term habitat degradation. We conclude that the high growth rate of the Svalbard-breeding pink-footed goose population suggests that increasing impacts of grubbing can be expected and argue that a responsible monitoring of the effects on the tundra ecosystem is crucial.

  7. Intra-basin variability of snowmelt water balance calculations in a subarctic catchment

    Science.gov (United States)

    McCartney, Stephen E.; Carey, Sean K.; Pomeroy, John W.

    2006-03-01

    The intra-basin variability of snowmelt and melt-water runoff hydrology in an 8 km2 subarctic alpine tundra catchment was examined for the 2003 melt period. The catchment, Granger Creek, is within the Wolf Creek Research Basin, Yukon, which is typical of mountain subarctic landscapes in northwestern Canada. The study catchment was segmented into nine internally uniform zones termed hydrological response units (HRUs) based on their similar hydrological, physiographic, vegetation and soil properties. Snow accumulation exhibited significant variability among the HRUs, with greatest snow water equivalent in areas of tall shrub vegetation. Melt began first on southerly exposures and at lower elevations, yet average melt rates for the study period varied little among HRUs with the exception of those with steep aspects. In HRUs with capping organic soils, melt water first infiltrated this surface horizon, satisfying its storage capacity, and then percolated into the frozen mineral substrate. Infiltration and percolation into frozen mineral soils was restricted where melt occurred rapidly and organic soils were thin; in this case, melt-water delivery rates exceeded the frozen mineral soil infiltration rate, resulting in high runoff rates. In contrast, where there were slower melt rates and thick organic soils, infiltration was unlimited and runoff was suppressed. The snow water equivalent had a large impact on runoff volume, as soil storage capacity was quickly surpassed in areas of deep snow, diverting the bulk of melt water laterally to the drainage network. A spatially distributed water balance indicated that the snowmelt freshet was primarily controlled by areas with tall shrub vegetation that accumulate large quantities of snow and by alpine areas with no capping organic soils. The intra-basin water balance variability has important implications for modelling freshet in hydrological models.

  8. Field-scale water balance closure in seasonally frozen conditions

    Directory of Open Access Journals (Sweden)

    X. Pan

    2017-11-01

    Full Text Available Hydrological water balance closure is a simple concept, yet in practice it is uncommon to measure every significant term independently in the field. Here we demonstrate the degree to which the field-scale water balance can be closed using only routine field observations in a seasonally frozen prairie pasture field site in Saskatchewan, Canada. Arrays of snow and soil moisture measurements were combined with a precipitation gauge and flux tower evapotranspiration estimates. We consider three hydrologically distinct periods: the snow accumulation period over the winter, the snowmelt period in spring, and the summer growing season. In each period, we attempt to quantify the residual between net precipitation (precipitation minus evaporation and the change in field-scale storage (snow and soil moisture, while accounting for measurement uncertainties. When the residual is negligible, a simple 1-D water balance with no net drainage is adequate. When the residual is non-negligible, we must find additional processes to explain the result. We identify the hydrological fluxes which confound the 1-D water balance assumptions during different periods of the year, notably blowing snow and frozen soil moisture redistribution during the snow accumulation period, and snowmelt runoff and soil drainage during the melt period. Challenges associated with quantifying these processes, as well as uncertainties in the measurable quantities, caution against the common use of water balance residuals to estimate fluxes and constrain models in such a complex environment.

  9. Surfactant and natural sunlight enhanced Photogalvanic effect of Sudan I dye

    Directory of Open Access Journals (Sweden)

    Pooran Koli

    2017-12-01

    Full Text Available Photogalvanic cells (PG have been extensively studied for solar power and storage at low intensity artificial sunlight. But, PG can be practically significant and applicable in daily life only when they are validated at natural sunlight intensity. Therefore, the present study of photogalvanics of Sudan I-Fructose with efficiency enhancer chemical such as Sodium Lauryl Sulfate (SLS surfactant in alkaline medium has been used to observe their workable feasibility in natural sunlight with investigation for optimal fabrication parameters. The cell has been found workable in natural sunlight with greatly enhanced optimum cell performance compared to that for reported similar cells. The observed optimum cell performance in terms of maximum power, short-circuit current, open-circuit potential, conversion efficiency and storage capacity (as half change time is of the order of 1081.1 μW, 4200 μA, 1048 mV, 13.5%, and 31 min, respectively.

  10. Influence of thermoluminescence signal for debris flow surface materials by sunlight bleaching

    International Nuclear Information System (INIS)

    Song Bo; Wei Mingjian; He Youbing; Zhou Rui; Zhao Qiuyue; Zhang Bin

    2013-01-01

    Thermoluminescence was utilized for measuring the thermoluminescence signals of the standard debris flow samples which were bleached by simulated sunlight and debris flow samples after real sunlight bleaching. The experiment results demonstrate that light bleaching phenomenon of the debris flow occurs when it experiences a period of exposure. The thermoluminescence signal of the samples weakens gradually with the increase of depth. The optical bleaching phenomenon is obvious. Within a certain depth, light bleaching phenomenon is enhanced with the increase of light intensity. The annealing depth of simulated sunlight bleaching experiment is about 1 mm, and the actual annealing depth of sunlight bleaching is about 6 mm. According to the equivalent dose variation with depth, the mud of natural debris flow can be divided into two stages. It has fundamental significance in the application of thermoluminescence dating techniques to divide the stages of debris flow sediments. (authors)

  11. Sunlight suppressing rejection of 280- to 320-nm UV-radiation-induced skin tumors in mice

    International Nuclear Information System (INIS)

    Morison, W.L.; Kelley, S.P.

    1985-01-01

    Repeated exposure of female C3H/HeNCR- mice to sunlight prevented the normal immunologic rejection of a UV-induced tumor. This systemic immunologic alteration was transferred to syngeneic lethally X-irradiated animals with lymphoid cells from mice exposed to sunlight. The lymphoid cells also were able to suppress the capacity of lymphoid cells from normal animals to reject a UV-induced tumor. The 295- to 320-nm wave band appeared to be responsible for this immunosuppressive effect of sunlight because suppression was prevented by filtration of the radiation through Mylar and by application of a sunscreen containing para-aminobenzoic acid. These observations may have importance in understanding the pathogenesis of sunlight-induced skin cancer in humans

  12. Long-term decline of the canopy-forming algae Gelidium corneum, associated to extreme wave events and reduced sunlight hours, in the southeastern Bay of Biscay

    Science.gov (United States)

    Borja, Angel; Chust, Guillem; Fontán, Almudena; Garmendia, Joxe Mikel; Uyarra, María C.

    2018-05-01

    Canopy-forming macroalgae are experiencing large biogeographical shifts due to climate change. One of them (Gelidium corneum) has shown a dramatic decline in biomass in northern Spain, in the past 20 years. We investigate here two most plausible hypotheses to explain its decline: (i) a combination of increasing wave energy and decrease of irradiance in the growth season; and (ii) a combination of increasing light in summer and decreasing nutrient concentration. Using a dataset of biomass and environmental variables (1993-2016), in three sectors and three water depths, we have determined that the variables explaining more biomass variability were: suspended solids, nitrate, sunlight hours, significant wave height threshold exceedances (Hs5m), temperature, silicate, and nitrite. When undertaking multiple regression analyses for the whole depth range, only the model including sunlight hours with Hs5m was selected, being highly significant (p algae from the substratum during the growth season. The decline rate in biomass with time, at each sector and depth, was highly correlated (p < 0.001) to the wave energy flux received at each depth, which was higher at 5 m in all sectors, decreasing with depth. In turn, nutrients, instead of decreasing, have increased, and only nitrate presented a significant negative correlation with G. corneum biomass, which was not significant after detrending. The significant (p = 0.001) increase in rainfall over the studied period can explain the increase of those nutrients. Hence, we question whether the effect of nutrients is such, as already described. The most likely factor explaining the decline of this macroalga was the combination of sunlight hours decrease and Hs5m increase.

  13. Toxicological impact of cadmium-based quantum dots towards aquatic biota: Effect of natural sunlight exposure

    Energy Technology Data Exchange (ETDEWEB)

    Silva, B.F. [Department of Biology, Faculty of Science, University of Porto, Rua do Campo Alegre, 4169-007 Porto (Portugal); CIIMAR, Interdisciplinary Centre of Marine and Environmental Research, Rua dos Bragas, 289, 4050-123 Porto (Portugal); Andreani, T. [Centro de Investigação em Química da Universidade do Porto, Rua do Campo Alegre, 687, 4169-007 Porto (Portugal); Department of Chemistry and Biochemistry, Faculty of Science, University of Porto, Rua do Campo Alegre, 4169-007 Porto (Portugal); CITAB − Centre for Research and Technology of Agro-Environmental and Biological Sciences, University of Trás-os-Montes e Alto Douro, UTAD, Vila Real (Portugal); Gavina, A., E-mail: anacsgavina@gmail.com [Department of Biology, Faculty of Science, University of Porto, Rua do Campo Alegre, 4169-007 Porto (Portugal); CIIMAR, Interdisciplinary Centre of Marine and Environmental Research, Rua dos Bragas, 289, 4050-123 Porto (Portugal); Vieira, M.N. [Department of Biology, Faculty of Science, University of Porto, Rua do Campo Alegre, 4169-007 Porto (Portugal); CIIMAR, Interdisciplinary Centre of Marine and Environmental Research, Rua dos Bragas, 289, 4050-123 Porto (Portugal); Pereira, C.M. [Centro de Investigação em Química da Universidade do Porto, Rua do Campo Alegre, 687, 4169-007 Porto (Portugal); Department of Chemistry and Biochemistry, Faculty of Science, University of Porto, Rua do Campo Alegre, 4169-007 Porto (Portugal); Rocha-Santos, T. [Department of Chemistry and Centre for Environmental and Marine Studies (CESAM), University of Aveiro, Campus de Santiago, 3810-193 Aveiro (Portugal); and others

    2016-07-15

    Highlights: • Under sunlight exposure, all QDs form particle aggregates in the different media. • CdSeS/ZnS QDs showed lower toxic effects to V. fischeri before sunlight exposure. • Sunlight exposure decreased the toxicity of CdS 480 in all organisms. • Sunlight exposure increased the toxicity of CdS 380 QDs for D. magna. • Shell of QDs seemed to make them less harmful to aquatic organisms. - Abstract: Cadmium-based quantum dots (QDs) are increasingly applied in existent and emerging technologies, especially in biological applications due to their exceptional photophysical and functionalization properties. However, they are very toxic compounds due to the high reactive and toxic cadmium core. The present study aimed to determine the toxicity of three different QDs (CdS 380, CdS 480 and CdSeS/ZnS) before and after the exposure of suspensions to sunlight, in order to assess the effect of environmentally relevant irradiation levels in their toxicity, which will act after their release to the environment. Therefore, a battery of ecotoxicological tests was performed with organisms that cover different functional and trophic levels, such as Vibrio fischeri, Raphidocelis subcapitata, Chlorella vulgaris and Daphnia magna. The results showed that core-shell type QDs showed lower toxic effects to V. fischeri in comparison to core type QDs before sunlight exposure. However, after sunlight exposure, there was a decrease of CdS 380 and CdS 480 QD toxicity to bacterium. Also, after sunlight exposure, an effective decrease of CdSeS/ZnS and CdS 480 toxicity for D. magna and R. subcapitata, and an evident increase in CdS 380 QD toxicity, at least for D. magna, were observed. The results of this study suggest that sunlight exposure has an effect in the aggregation and precipitation reactions of larger QDs, causing the degradation of functional groups and formation of larger bulks which may be less prone to photo-oxidation due to their diminished surface area. The same

  14. Coupling the WRF model with a temperature index model based on remote sensing for snowmelt simulations in a river basin in the Altay Mountains, northwest China

    Science.gov (United States)

    Wu, X.; Shen, Y.; Wang, N.; Pan, X.; Zhang, W.; He, J.; Wang, G.

    2017-12-01

    Snowmelt water is an important freshwater resource in the Altay Mountains in northwest China, and it is also crucial for local ecological system, economic and social sustainable development; however, warming climate and rapid spring snowmelt can cause floods that endanger both eco-environment and public and personal property and safety. This study simulates snowmelt in the Kayiertesi River catchment using a temperature-index model based on remote sensing coupled with high-resolution meteorological data obtained from NCEP reanalysis fields that were downscaled using Weather Research Forecasting model, then bias-corrected using a statistical downscaled model. Validation of the forcing data revealed that the high-resolution meteorological fields derived from downscaled NCEP reanalysis were reliable for driving the snowmelt model. Parameters of temperature-index model based on remote sensing were calibrated for spring 2014, and model performance was validated using MODIS snow cover and snow observations from spring 2012. The results show that the temperature-index model based on remote sensing performed well, with a simulation mean relative error of 6.7% and a Nash-Sutchliffe efficiency of 0.98 in spring 2012 in the river of Altay Mountains. Based on the reliable distributed snow water equivalent simulation, daily snowmelt runoff was calculated for spring 2012 in the basin. In the study catchment, spring snowmelt runoff accounts for 72% of spring runoff and 21% of annual runoff. Snowmelt is the main source of runoff for the catchment and should be managed and utilized effectively. The results provide a basis for snowmelt runoff predictions, so as to prevent snowmelt-induced floods, and also provide a generalizable approach that can be applied to other remote locations where high-density, long-term observational data is lacking.

  15. Natural Sunlight Shapes Crude Oil-Degrading Bacterial Communities in Northern Gulf of Mexico Surface Waters

    OpenAIRE

    Bacosa, Hernando P.; Liu, Zhanfei; Erdner, Deana L.

    2015-01-01

    Following the Deepwater Horizon (DWH) spill in 2010, an enormous amount of oil was observed in the deep and surface waters of the northern Gulf of Mexico. Surface waters are characterized by intense sunlight and high temperature during summer. While the oil-degrading bacterial communities in the deep-sea plume have been widely investigated, the effect of natural sunlight on those in oil polluted surface waters remains unexplored to date. In this study, we incubated surface water from the DWH ...

  16. Snowmelt and sublimation: field experiments and modelling in the High Atlas Mountains of Morocco

    Directory of Open Access Journals (Sweden)

    O. Schulz

    2004-01-01

    Full Text Available Snow in the High Atlas Mountains is a major source for freshwater renewal and for water availability in the semi-arid lowlands of south-eastern Morocco. Snowfall- and snow-ablation monitoring and modelling is important for estimating potential water delivery from the mountain water towers to the forelands. This study is part of GLOWA-IMPETUS, an integrated management project dealing with scarce water resources in West Africa. The Ameskar study area is located to the south of the High Atlas Mountains, in their rain shadow. As a part of the M’Goun river basin within the upper Drâa valley, the study area is characterised by high radiation inputs, low atmospheric humidity and long periods with sub-zero temperatures. Its altitude ranges between 2000 m and 4000 m, with dominant north- and south-facing slopes. Snowfall occurs mainly from November to April but even summit regions can become repeatedly devoid of snow cover. Snow cover maps for the M’Goun basin (1240 km2 are derived from calculations of NDSI (Normalized Difference Snow Index from MODIS satellite images and snow depth is monitored at four automatic weather stations between 2000–4000 m. Snowfall events are infrequent at lower altitudes. The presence of snow penitentes at altitudes above 3000 m indicates that snow sublimation is an important component of snow ablation. Snow ablation was modelled with the UEB Utah Energy Balance Model (Tarboton and Luce, 1996. This single layer, physically-based, point energy and mass balance model is driven by meteorological variables recorded at the automatic weather stations at Tounza (2960 m and Tichki (3260 m. Data from snow pillows at Tounza and Tichki are used to validate the model’s physical performance in terms of energy and water balances for a sequence of two snowfall events in the winter of 2003/4. First UEB modelling results show good overall performance and timing of snowmelt and sublimation compared to field investigations. Up to 44

  17. Natural sunlight shapes crude oil-degradingbacterial communities in northern Gulf of Mexico surface waters

    Directory of Open Access Journals (Sweden)

    Hernando P Bacosa

    2015-12-01

    Full Text Available Following the Deepwater Horizon (DWH spill in 2010, an enormous amount of oil was observed in the deep and surface waters of the northern Gulf of Mexico. Surface waters are characterized by intense sunlight and high temperature during summer. While the oil-degrading bacterial communities in the deep-sea plume have been widely investigated, the effect of natural sunlight on those in oil polluted surface waters remains unexplored to date. In this study, we incubated surface water from the DWH site with amendments of crude oil, Corexit dispersant, or both for 36 d under natural sunlight in the northern Gulf of Mexico. The bacterial community was analyzed over time for total abundance, density of alkane and polycyclic aromatic hydrocarbon degraders, and community composition via pyrosequencing. Our results showed that, for treatments with oil and/or Corexit, sunlight significantly reduced bacterial diversity and evenness and was a key driver of shifts in bacterial community structure. In samples containing oil or dispersant, sunlight greatly reduced abundance of the Cyanobacterium Synechococcus but increased the relative abundances of Alteromonas, Marinobacter, Labrenzia, Sandarakinotalea, Bartonella, and Halomonas. Dark samples with oil were represented by members of Thalassobius, Winogradskyella, Alcanivorax, Formosa, Pseudomonas, Eubacterium, Erythrobacter, Natronocella, and Coxiella. Both oil and Corexit inhibited the Candidatus Pelagibacter with or without sunlight exposure. For the first time, we demonstrated the effects of light in structuring microbial communities in water with oil and/or Corexit. Overall, our findings improve understanding of oil pollution in surface water, and provide unequivocal evidence that sunlight is a key factor in determining bacterial community composition and dynamics in oil polluted marine waters.

  18. Natural Sunlight Shapes Crude Oil-Degrading Bacterial Communities in Northern Gulf of Mexico Surface Waters.

    Science.gov (United States)

    Bacosa, Hernando P; Liu, Zhanfei; Erdner, Deana L

    2015-01-01

    Following the Deepwater Horizon (DWH) spill in 2010, an enormous amount of oil was observed in the deep and surface waters of the northern Gulf of Mexico. Surface waters are characterized by intense sunlight and high temperature during summer. While the oil-degrading bacterial communities in the deep-sea plume have been widely investigated, the effect of natural sunlight on those in oil polluted surface waters remains unexplored to date. In this study, we incubated surface water from the DWH site with amendments of crude oil, Corexit dispersant, or both for 36 days under natural sunlight in the northern Gulf of Mexico. The bacterial community was analyzed over time for total abundance, density of alkane and polycyclic aromatic hydrocarbon degraders, and community composition via pyrosequencing. Our results showed that, for treatments with oil and/or Corexit, sunlight significantly reduced bacterial diversity and evenness and was a key driver of shifts in bacterial community structure. In samples containing oil or dispersant, sunlight greatly reduced abundance of the Cyanobacterium Synechococcus but increased the relative abundances of Alteromonas, Marinobacter, Labrenzia, Sandarakinotalea, Bartonella, and Halomonas. Dark samples with oil were represented by members of Thalassobius, Winogradskyella, Alcanivorax, Formosa, Pseudomonas, Eubacterium, Erythrobacter, Natronocella, and Coxiella. Both oil and Corexit inhibited the Candidatus Pelagibacter with or without sunlight exposure. For the first time, we demonstrated the effects of light in structuring microbial communities in water with oil and/or Corexit. Overall, our findings improve understanding of oil pollution in surface water, and provide unequivocal evidence that sunlight is a key factor in determining bacterial community composition and dynamics in oil polluted marine waters.

  19. Recent changes in spring snowmelt timing in the Yukon River basin detected by passive microwave satellite data

    Directory of Open Access Journals (Sweden)

    K. A. Semmens

    2013-06-01

    Full Text Available Spring melt is a significant feature of high latitude snowmelt dominated drainage basins influencing hydrological and ecological processes such as snowmelt runoff and green-up. Melt duration, defined as the transition period from snowmelt onset until the end of the melt refreeze, is characterized by high diurnal amplitude variations (DAV where the snowpack is melting during the day and refreezing at night, after which the snowpack melts constantly until depletion. Determining trends for this critical period is necessary for understanding how the Arctic is changing with rising temperatures and provides a baseline from which to assess future change. To study this dynamic period, brightness temperature (Tb data from the Special Sensor Microwave Imager (SSM/I 37 V-GHz frequency from 1988 to 2010 were used to assess snowmelt timing trends for the Yukon River basin, Alaska/Canada. Annual Tb and DAV for 1434 Equal-Area Scalable Earth (EASE-Grid pixels (25 km resolution were processed to determine melt onset and melt refreeze dates from Tb and DAV thresholds previously established in the region. Temporal and spatial trends in the timing of melt onset and melt refreeze, and the duration of melt were analyzed for the 13 sub-basins of the Yukon River basin with three different time interval approaches. Results show a lengthening of the melt period for the majority of the sub-basins with a significant trend toward later end of melt refreeze after which the snowpack melts day and night leading to snow clearance, peak discharge, and green-up. Earlier melt onset trends were also found in the higher elevations and northernmost sub-basins (Porcupine, Chandalar, and Koyukuk rivers. Latitude and elevation displayed the dominant controls on melt timing variability and spring solar flux was highly correlated with melt timing in middle (∼600–1600 m elevations.

  20. Characterization of aircraft deicer and anti-icer components and toxicity in airport snowbanks and snowmelt runoff

    Science.gov (United States)

    Corsi, S.R.; Geis, S.W.; Loyo-Rosales, J. E.; Rice, C.P.; Sheesley, R.J.; Failey, G.G.; Cancilla, Devon A.

    2006-01-01

    Snowbank samples were collected from snowbanks within a medium-sized airport for four years to characterize aircraft deicer and anti-icer (ADAF) components and toxicity. Concentrations of ADAF components varied with median glycol concentrations from individual sampling periods ranging from 65 to 5940 mg/L. Glycol content in snowbanks ranged from 0.17 to 11.4% of that applied to aircraft. Glycol, a freezing point depressant, was selectively removed during melt periods before snow and ice resulting in lower glycol concentrations after melt periods. Concentrations of ADAF components in airport runoff were similar during periods of snowmelt as compared to active ADAF application periods; however, due to the long duration of snowmelt events, greater masses of glycol were transported during snowmelt events. Alkylphenol ethoxylates (APEO), selected APEO degradation products, and 4- and 5-methyl-1H-benzotriazole were detected in snowbank samples and airport snowmelt. Concentrations of APEO parent products were greater in snowbank samples than in runoff samples. Relative abundance of APEO degradation products increased in the downstream direction from the snowbank to the outfalls and the receiving stream with respect to APEO parent compounds and glycol. Toxicity in Microtox assays remained in snowbanks after most glycol had been removed during melt periods. Increased toxicity in airport snowbanks as compared to other urban snowbanks was not explained by additional combustion or fuel contribution in airport snow. Organic markers suggest ADAF additives as a possible explanation for this increased toxicity. Results indicate that glycol cannot be used as a surrogate for fate and transport of other ADAF components. ?? 2006 American Chemical Society.

  1. Performance and Uncertainty Evaluation of Snow Models on Snowmelt Flow Simulations over a Nordic Catchment (Mistassibi, Canada

    Directory of Open Access Journals (Sweden)

    Magali Troin

    2015-11-01

    Full Text Available An analysis of hydrological response to a multi-model approach based on an ensemble of seven snow models (SM; degree-day and mixed degree-day/energy balance models coupled with three hydrological models (HM is presented for a snowmelt-dominated basin in Canada. The present study aims to compare the performance and the reliability of different types of SM-HM combinations at simulating snowmelt flows over the 1961–2000 historical period. The multi-model approach also allows evaluating the uncertainties associated with the structure of the SM-HM ensemble to better predict river flows in Nordic environments. The 20-year calibration shows a satisfactory performance of the ensemble of 21 SM-HM combinations at simulating daily discharges and snow water equivalents (SWEs, with low streamflow volume biases. The validation of the ensemble of 21 SM-HM combinations is conducted over a 20-year period. Performances are similar to the calibration in simulating the daily discharges and SWEs, again with low model biases for streamflow. The spring-snowmelt-generated peak flow is captured only in timing by the ensemble of 21 SM-HM combinations. The results of specific hydrologic indicators show that the uncertainty related to the choice of the given HM in the SM-HM combinations cannot be neglected in a more quantitative manner in simulating snowmelt flows. The selection of the SM plays a larger role than the choice of the SM approach (degree-day versus mixed degree-day/energy balance in simulating spring flows. Overall, the snow models provide a low degree of uncertainty to the total uncertainty in hydrological modeling for snow hydrology studies.

  2. Changes in snowmelt runoff timing in western North America under a 'business as usual' climate change scenario

    Science.gov (United States)

    Stewart, I.T.; Cayan, D.R.; Dettinger, M.D.

    2004-01-01

    Spring snowmelt is the most important contribution of many rivers in western North America. If climate changes, this contribution may change. A shift in the timing of springtime snowmelt towards earlier in the year already is observed during 1948-2000 in many western rivers. Streamflow timing changes for the 1995-2099 period are projected using regression relations between observed streamflow-timing responses in each river, measured by the temporal centroid of streamflow (CT) each year, and local temperature (TI) and precipitation (PI) indices. Under 21st century warming trends predicted by the Parallel Climate Model (PCM) under business-as-usual greenhouse-gas emissions, streamflow timing trends across much of western North America suggest even earlier springtime snowmelt than observed to date. Projected CT changes are consistent with observed rates and directions of change during the past five decades, and are strongest in the Pacific Northwest, Sierra Nevada, and Rocky Mountains, where many rivers eventually run 30-40 days earlier. The modest PI changes projected by PCM yield minimal CT changes. The responses of CT to the simultaneous effects of projected TI and PI trends are dominated by the TI changes. Regression-based CT projections agree with those from physically-based simulations of rivers in the Pacific Northwest and Sierra Nevada.

  3. Improving the performance of temperature index snowmelt model of SWAT by using MODIS land surface temperature data.

    Science.gov (United States)

    Yang, Yan; Onishi, Takeo; Hiramatsu, Ken

    2014-01-01

    Simulation results of the widely used temperature index snowmelt model are greatly influenced by input air temperature data. Spatially sparse air temperature data remain the main factor inducing uncertainties and errors in that model, which limits its applications. Thus, to solve this problem, we created new air temperature data using linear regression relationships that can be formulated based on MODIS land surface temperature data. The Soil Water Assessment Tool model, which includes an improved temperature index snowmelt module, was chosen to test the newly created data. By evaluating simulation performance for daily snowmelt in three test basins of the Amur River, performance of the newly created data was assessed. The coefficient of determination (R (2)) and Nash-Sutcliffe efficiency (NSE) were used for evaluation. The results indicate that MODIS land surface temperature data can be used as a new source for air temperature data creation. This will improve snow simulation using the temperature index model in an area with sparse air temperature observations.

  4. Snowmelt induced hydrologic perturbations drive dynamic microbiological and geochemical behaviors across a shallow riparian aquifer

    Directory of Open Access Journals (Sweden)

    Robert eDanczak

    2016-05-01

    Full Text Available Shallow riparian aquifers represent hotspots of biogeochemical activity in the arid western US. While these environments provide extensive ecosystem services, little is known of how natural environmental perturbations influence subsurface microbial communities and associated biogeochemical processes. Over a six-month period we tracked the annual snowmelt-driven incursion of groundwater into the vadose zone of an aquifer adjacent to the Colorado River, leading to increased dissolved oxygen (DO concentrations in the normally suboxic saturated zone. Strong biogeochemical heterogeneity was measured across the site, with abiotic reactions between DO and sulfide minerals driving rapid DO consumption and mobilization of redox active species in reduced aquifer regions. Conversely, extensive DO increases were detected in less reduced sediments. 16S rRNA gene surveys tracked microbial community composition within the aquifer, revealing strong correlations between increases in putative oxygen-utilizing chemolithoautotrophs and heterotrophs and rising DO concentrations. The gradual return to suboxic aquifer conditions favored increasing abundances of 16S rRNA sequences matching members of the Microgenomates (OP11 and Parcubacteria (OD1 that have been strongly implicated in fermentative processes. Microbial community stability measurements indicated that deeper aquifer locations were relatively less affected by geochemical perturbations, while communities in shallower locations exhibited the greatest change. Reactive transport modeling of the geochemical and microbiological results supported field observations, suggesting that a predictive framework can be applied to develop a greater understanding of such environments.

  5. Application of the Snowmelt Runoff model in the Kuban river basin using MODIS satellite images

    International Nuclear Information System (INIS)

    Georgievsky, M V

    2009-01-01

    This paper analyses an opportunity to integrate remote sensing data in a forecasting scheme of river inflow to the Krasnodar reservoir. MODIS MOD10A2 eight-day composite snow cover data was selected as the basic remote sensing information. Based on these data, a database which consists of maximal snow extent maps covering the Kuban river basin over the period from March 2000 to the present, along with the technique of operative monitoring of the maximal snow covered area for the main basins of the rivers flowing into the Krasnodar reservoir were developed. It was revealed that the snow cover distribution data could be useful in the prediction of flooding in the basin. In addition, the Snowmelt Runoff model, application of which is based on snow cover remote sensing data as the input information, was tested as a short-term forecasting model. The obtained results enable us to conclude that the model can be used for short-term runoff forecasts in the mountain and foothill areas of the Krasnodar reservoir basin.

  6. Application of the Snowmelt Runoff model in the Kuban river basin using MODIS satellite images

    Energy Technology Data Exchange (ETDEWEB)

    Georgievsky, M V, E-mail: mgeorgievsky@hotmail.co [State Hydrological Institute, St Petersburg (Russian Federation)

    2009-10-15

    This paper analyses an opportunity to integrate remote sensing data in a forecasting scheme of river inflow to the Krasnodar reservoir. MODIS MOD10A2 eight-day composite snow cover data was selected as the basic remote sensing information. Based on these data, a database which consists of maximal snow extent maps covering the Kuban river basin over the period from March 2000 to the present, along with the technique of operative monitoring of the maximal snow covered area for the main basins of the rivers flowing into the Krasnodar reservoir were developed. It was revealed that the snow cover distribution data could be useful in the prediction of flooding in the basin. In addition, the Snowmelt Runoff model, application of which is based on snow cover remote sensing data as the input information, was tested as a short-term forecasting model. The obtained results enable us to conclude that the model can be used for short-term runoff forecasts in the mountain and foothill areas of the Krasnodar reservoir basin.

  7. Snowmelt induced hydrologic perturbations drive dynamic microbiological and geochemical behaviors across a shallow riparian aquifer

    Science.gov (United States)

    Danczak, Robert; Yabusaki, Steven; Williams, Kenneth; Fang, Yilin; Hobson, Chad; Wilkins, Michael

    2016-05-01

    Shallow riparian aquifers represent hotspots of biogeochemical activity in the arid western US. While these environments provide extensive ecosystem services, little is known of how natural environmental perturbations influence subsurface microbial communities and associated biogeochemical processes. Over a six-month period we tracked the annual snowmelt-driven incursion of groundwater into the vadose zone of an aquifer adjacent to the Colorado River, leading to increased dissolved oxygen (DO) concentrations in the normally suboxic saturated zone. Strong biogeochemical heterogeneity was measured across the site, with abiotic reactions between DO and sulfide minerals driving rapid DO consumption and mobilization of redox active species in reduced aquifer regions. Conversely, extensive DO increases were detected in less reduced sediments. 16S rRNA gene surveys tracked microbial community composition within the aquifer, revealing strong correlations between increases in putative oxygen-utilizing chemolithoautotrophs and heterotrophs and rising DO concentrations. The gradual return to suboxic aquifer conditions favored increasing abundances of 16S rRNA sequences matching members of the Microgenomates (OP11) and Parcubacteria (OD1) that have been strongly implicated in fermentative processes. Microbial community stability measurements indicated that deeper aquifer locations were relatively less affected by geochemical perturbations, while communities in shallower locations exhibited the greatest change. Reactive transport modeling of the geochemical and microbiological results supported field observations, suggesting that a predictive framework can be applied to develop a greater understanding of such environments.

  8. Sunlight stability and rain-fastness of formulations of Baculovirus heliothis

    International Nuclear Information System (INIS)

    Ignoffo, C.M.; Garcia, C.; Saathoff, S.G.

    1997-01-01

    Sunlight-Ultraviolet, with an activity spectrum from 290 to 400 nm, is the most destructive factor affecting the persistence of baculoviruses. Benzopurpurin (a disazo dye) and carbon provided the best protection when polyhedral inclusion bodies (PIB) of Baculovirus heliothis were exposed to an artificial spectrum simulating sunlight-UV (UV). Greater than 75% of the original PIB activity was still present after 48 h of sunlight-UV. When sprayed on soybeans and exposed to natural sunlight, only formulations with carbon provided significant protection of PIB. The half-life of formulations were PIB-only 4.9 +/- 1.4 h (mean +/- SE), PIB + polymer (pyrrolidone-based sticker) 3.3 +/- 0.6 h, PIB + polymer + benzopurpurin 3.4 +/- 0.7 h, and PIB + polymer + carbon 27.7 +/- 5.2 h. PIB of B. heliothis tenaciously adhere to soybean, Glycine max (L.) Merrill, leaflets after spraying and drying. Less than 6% of the PIB activity of nonformulated PIB was lost after a drenching, simulated rainfall. More than 97% of the original PIB activity of carbon formulations was still present on soybean leaflets after 10 h of exposure to sunlight-UV. In contrast, 20% was present for formulations without carbon

  9. Hypovitaminosis D in patients undergoing kidney transplant: the importance of sunlight exposure

    Directory of Open Access Journals (Sweden)

    Cristiane F. Vilarta

    Full Text Available OBJECTIVES: Recent studies have shown a high prevalence of hypovitaminosis D, defined as a serum 25-hydroxyvitamin D level less than 30 ng/ml, in both healthy populations and patients with chronic kidney disease. Patients undergoing kidney transplant are at an increased risk of skin cancer and are advised to avoid sunlight exposure. Therefore, these patients might share two major risk factors for hypovitaminosis D: chronic kidney disease and low sunlight exposure. This paper describes the prevalence and clinical characteristics of hypovitaminosis D among patients undergoing kidney transplant. METHODS: We evaluated 25-hydroxyvitamin D serum levels in a representative sample of patients undergoing kidney transplant. We sought to determine the prevalence of hypovitaminosis D, compare these patients with a control group, and identify factors associated with hypovitaminosis D (e.g., sunlight exposure and dietary habits. RESULTS: Hypovitaminosis D was found in 79% of patients undergoing kidney transplant, and the major associated factor was low sunlight exposure. These patients had higher creatinine and intact parathyroid hormone serum levels, with 25-hydroxyvitamin D being inversely correlated with intact parathyroid hormone serum levels. Compared with the control group, patients undergoing kidney transplant presented a higher prevalence of 25-hydroxyvitamin D deficiency and lower serum calcium, phosphate and albumin but higher creatinine and intact parathyroid hormone levels. CONCLUSIONS: Our results confirmed the high prevalence of hypovitaminosis D in patients undergoing kidney transplant. Therapeutic strategies such as moderate sunlight exposure and vitamin D supplementation should be seriously considered for this population.

  10. Commonly recommended daily intake of vitamin D is not sufficient if sunlight exposure is limited

    DEFF Research Database (Denmark)

    Glerup, H; Mikkelsen, K; Poulsen, L

    2000-01-01

    OBJECTIVES: Sunlight exposure of the skin is known to be the most important source of vitamin D. The aims of this study were: (i) to estimate vitamin D status amongst sunlight-deprived individuals (veiled Arab women, veiled ethnic Danish Moslem women and Danish controls); and (ii) through food...... intake analysis to estimate the oral intake of vitamin D necessary to keep a normal vitamin D status in sunlight-deprived individuals. DESIGN: Cross-sectional study amongst randomly selected Moslem women of Arab origin living in Denmark. Age-matched Danish women were included as controls. To control...... for racial differences, a group of veiled ethnic Danish Moslem women (all Caucasians) was included. SETTING: Primary Health Care Centre, City Vest and Department of Endocrinology and Metabolism C, University Hospital of Aarhus, Aarhus Amtssygehus, Aarhus, Denmark. SUBJECTS: Sixty-nine Arab women (60 veiled...

  11. Effect of sunlight on the survival of pathogenic E. coli in freshwater and sea water

    DEFF Research Database (Denmark)

    Surendraraj, Alagarsamy; Farvin, Sabeena; Thampuran, N.

    2011-01-01

    An enteropathogenic group of E. coli are the emerging category of pathogen of public health significance. Several recent pathogenic E. coli outbreaks are associated with drinking water. Aquaculture, the fast emerging food production sector also poses a pathogenic EHEC outbreak risk, as it regularly...... uses cow dung, a reservoir of this organism. Hence, a experiment was set up to study the duration of survival of pathogenic E. coli under sunlight and darkness. Eight pathogenic E. coli isolates from clinical (EPEC, ETEC, EHEC, EAEC), veterinary (CTE3, CTE4) and environmental sources (ASHE3, Rao II......) were studied for their survival under sunlight and darkness in fresh water and seawater. Effect of direct sunlight on the viable but nonculturable (VBNC) state of cultures was also studied. The results of the study indicated a distinct pattern between freshwater system and seawater system. Pathogenic E...

  12. Roles of sunlight and natural ventilation for controlling infection: historical and current perspectives.

    Science.gov (United States)

    Hobday, R A; Dancer, S J

    2013-08-01

    Infections caught in buildings are a major global cause of sickness and mortality. Understanding how infections spread is pivotal to public health yet current knowledge of indoor transmission remains poor. To review the roles of natural ventilation and sunlight for controlling infection within healthcare environments. Comprehensive literature search was performed, using electronic and library databases to retrieve English language papers combining infection; risk; pathogen; and mention of ventilation; fresh air; and sunlight. Foreign language articles with English translation were included, with no limit imposed on publication date. In the past, hospitals were designed with south-facing glazing, cross-ventilation and high ceilings because fresh air and sunlight were thought to reduce infection risk. Historical and recent studies suggest that natural ventilation offers protection from transmission of airborne pathogens. Particle size, dispersal characteristics and transmission risk require more work to justify infection control practices concerning airborne pathogens. Sunlight boosts resistance to infection, with older studies suggesting potential roles for surface decontamination. Current knowledge of indoor transmission of pathogens is inadequate, partly due to lack of agreed definitions for particle types and mechanisms of spread. There is recent evidence to support historical data on the effects of natural ventilation but virtually none for sunlight. Modern practice of designing healthcare buildings for comfort favours pathogen persistence. As the number of effective antimicrobial agents declines, further work is required to clarify absolute risks from airborne pathogens along with any potential benefits from additional fresh air and sunlight. Copyright © 2013 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.

  13. Cathodic protection of carbon steel in natural seawater: Effect of sunlight radiation

    Energy Technology Data Exchange (ETDEWEB)

    Benedetti, Alessandro [Istituto per l' Energetica e le Interfasi, IENI - CNR, Milano, via Roberto Cozzi 53 20125 Milano (Italy)], E-mail: alessandro.benedetti@cnr.it; Magagnin, Luca [Dip. Chimica, Materiali e Ing. Chimica G. Natta, Politecnico di Milano, via Mancinelli 7, 20131 Milano (Italy); Passaretti, Francesca [Istituto per l' Energetica e le Interfasi IENI - CNR, Lecco, c.so Promessi Sposi 29, 23900 Lecco (Italy); Chelossi, Elisabetta; Faimali, Marco [Istituto di Scienze Marine, ISMAR- CNR - Via De Marini 6, 16149, Genova (Italy); Montesperelli, Giampiero [Universita di Roma - Tor Vergata, Dipartimento di Scienze e Tecnologie Chimiche, Via della Ricerca Scientifica 00133, Roma (Italy)

    2009-11-01

    Cathodic protection of metals in seawater is known to be influenced by chemical-physical parameters affecting cathodic processes (oxygen discharge, hydrogen evolution and calcareous deposit precipitation). In shallow seawater, these parameters are influenced by sunlight photoperiod and photosynthetic activity. The results presented here represent the first step in studies dedicated to cathodic protection in shallow photic seawater. This paper reports on carbon steel protected at -850 mV vs. Ag/AgCl (oxygen limiting current regime) in the presence of sunlight radiation but in the absence of biological and photosynthetic activity, the role of which deserves future research. Comparison of results obtained by exposing electrochemical cells to daylight cycles in both biologically inactivated natural seawater and in NaCl 3.5 wt.% solutions showed that sunlight affects current densities and that calcareous deposit interfere with light-currents effects. Sunlight radiation and induced heating of the solution have been separated, highlighting results not otherwise obvious: (1) observed current waves concomitant with sunlight radiation depend fundamentally on solar radiation, (2) solar radiation can determine current enhancements from early to late phases of aragonite crystal growth, (3) a three-day-old CaCO{sub 3} layer reduces but does not eliminate the amplitude of the current waves. Theoretical calculations for oxygen limiting currents and additional field tests showed that sunlight, rather than bulk solution heating, is the main cause of daily current enhancements. This was confirmed by polarizations performed at -850 and -1000 mV vs. Ag/AgCl (constant bulk temperature), during which the electrode was irradiated with artificial lighting. This test also confirmed O{sub 2} discharge to be the cathodic process involved. A mechanism of radiation conversion to heat in the oxygen diffusion layer region is proposed.

  14. Comparison of germicidal activity of sunlight with the response of a sunburning meter

    Energy Technology Data Exchange (ETDEWEB)

    Billen, D; Green, A E.S.

    1975-01-01

    In the present work, we compare germicidal activity of sunlight on strain AB 2480 with the irradiance of sunlight as measured with a Sunburning Ultraviolet Meter (manufactured by the Skin and Cancer Hospital, Temple University Health Sciences Center, Philadelphia, Pennsylvania). This instrument, an adaptation by Berger of one developed by Robertson (1972), uses a magnesium tungstate phosphor with a response approximating that of the erythema action spectrum. The light emitted by the phosphor is detected by a phototube which produces a proportional electric current, the signal used in these experiments. (auth)

  15. Errors in short circuit measurements due to spectral mismatch between sunlight and solar simulators

    Science.gov (United States)

    Curtis, H. B.

    1976-01-01

    Errors in short circuit current measurement were calculated for a variety of spectral mismatch conditions. The differences in spectral irradiance between terrestrial sunlight and three types of solar simulator were studied, as well as the differences in spectral response between three types of reference solar cells and various test cells. The simulators considered were a short arc xenon lamp AMO sunlight simulator, an ordinary quartz halogen lamp, and an ELH-type quartz halogen lamp. Three types of solar cells studied were a silicon cell, a cadmium sulfide cell and a gallium arsenide cell.

  16. Spatial variability of shortwave radiative fluxes in the context of snowmelt

    Science.gov (United States)

    Pinker, Rachel T.; Ma, Yingtao; Hinkelman, Laura; Lundquist, Jessica

    2014-05-01

    Snow-covered mountain ranges are a major source of water supply for run-off and groundwater recharge. Snowmelt supplies as much as 75% of surface water in basins of the western United States. Factors that affect the rate of snow melt include incoming shortwave and longwave radiation, surface albedo, snow emissivity, snow surface temperature, sensible and latent heat fluxes, ground heat flux, and energy transferred to the snowpack from deposited snow or rain. The net radiation generally makes up about 80% of the energy balance and is dominated by the shortwave radiation. Complex terrain poses a great challenge for obtaining the needed information on radiative fluxes from satellites due to elevation issues, spatially-variable cloud cover, rapidly changing surface conditions during snow fall and snow melt, lack of high quality ground truth for evaluation of the satellite based estimates, as well as scale issues between the ground observations and the satellite footprint. In this study we utilize observations of high spatial resolution (5-km) as available from the Moderate Resolution Imaging Spectro-radiometer (MODIS) to derive surface shortwave radiative fluxes in complex terrain, with attention to the impact of slopes on the amount of radiation received. The methodology developed has been applied to several water years (January to July during 2003, 2004, 2005 and 2009) over the western part of the United States, and the available information was used to derive metrics on spatial and temporal variability in the shortwave fluxes. It is planned to apply the findings from this study for testing improvements in Snow Water Equivalent (SWE) estimates.

  17. Snowmelt runoff from northern alpine tundra hillslopes: major processes and methods of simulation

    Directory of Open Access Journals (Sweden)

    W. L. Quinton

    2004-01-01

    Full Text Available In northern alpine tundra, large slope gradients, late-lying snow drifts and shallow soils overlying impermeable substrates all contribute to large hillslope runoff volumes during the spring freshet. Understanding the processes and pathways of hillslope runoff in this environment is, therefore, critical to understanding the water cycle within northern alpine tundra ecosystems. This study: (a presents the results of a field study on runoff from a sub-alpine tundra hillslope with a large snow drift during the spring melt period; (b identifies the major runoff processes that must be represented in simulations of snowmelt runoff from sub-alpine tundra hillslopes; (c describes how these processes can be represented in a numerical simulation model; and d compares field measurements with modelled output to validate or refute the conceptual understanding of runoff generation embodied in the process simulations. The study was conducted at Granger Creek catchment, 15 km south of Whitehorse, Yukon Territory, Canada, on a north-facing slope below a late-lying snow drift. For the freshet period, the major processes to be represented in a runoff model include the rate of meltwater release from the late-lying snowdrift, the elevation and thickness of the saturated layer, the magnitude of the soil permeability and its variation with depth. The daily cycle of net all-wave radiation was observed to drive the diurnal pulses of melt water from the drift; this, in turn, was found to control the daily pulses of flow through the hillslope subsurface and in the stream channel. The computed rate of frost table lowering fell within the observed values; however, there was wide variation among the measured frost table depths. Spatial variability in frost table depth would result in spatial variabilities in saturated layer depth and thickness, which would, in turn, produce variations in subsurface flow rates over the slope, including preferential flowpaths. Keywords

  18. The Impact of a Kinesthetic Approach to Teaching Earth's Seasons

    Science.gov (United States)

    Slater, Stephanie; Morrow, C. A.

    2010-01-01

    The AAAS Benchmarks and NRC National Science Education Standards clearly prescribe that all American middle school students should understand that Earth's seasons are caused by variations in the amount of sunlight that hits Earth's surface due to tilt. An explanation for the cause of the seasons that is consistent with a scientifically accurate viewpoint would involve how the amount of sunlight reaching Earth's surface at different latitudes and is directly related to the planet's tilt. However, the most common alternative explanation given is the changing distance between the Sun and Earth. Previous research, as well as common experience, indicates that conventional instructional approaches on the concept of seasons are rarely sufficient in achieving scientifically accurate or durable conceptual change. Given the highly spatial nature of the concept, and the highly socially nature of human beings, some curriculum developers have turned to kinesthetic instructional approaches as a means to develop students' spatial reasoning and problem solving skills while confronting misconceptions and allowing students to socially construct scientifically accurate models of the seasons. We report results from a quantitative study on the impact on understanding of ninth grade students using kinesthetic approach to instruction for the traditionally challenging topic of Earth's seasons. The guiding research question was: To what extent does the kinesthetic astronomy instructional approach assist students in correcting misconceptions about the cause of the seasons? Using a single-group, multiple measures quasi-experimental study design, data was collected pre- and post-instruction using written, student-supplied-response assessments. Additionally, a third assessment was conducted 8 weeks after instruction in an attempt to measure durability. The results showed that statistically significant conceptual change occurred across three subtopics supporting seasons and were stable over 8

  19. Influenza Seasonal Summary, 2014-2015 Season

    Science.gov (United States)

    2015-08-14

    Influenza Seasonal Summarv 2014-2015 Season EpiData Center Department Communicable Disease Division NMCPHC-EDC-TR-394-2015 REPORT DOCUMENTATION... Influenza Seasonal Summary, 2014-2015 Season Sb. GRANT NUMBER $c. PROGRAM ELEMENT NUMBER 6. AUTHORjS) Sd. PROJECT NUMBER Ashleigh K McCabe, Kristen R...SUPPLEMENTARY NOTES 1<l. ABSTRACT This report summartzes influenza activity among Department of Navy (DON) and Depar1ment of Defense (DOD

  20. Seasonality, mobility, and livability.

    Science.gov (United States)

    2012-01-31

    Signature project 4a, Seasonality, Mobility, and Livability investigated the effects of weather, season, built environment, community amenities, attitudes, and demographics on mobility and quality of life (QOL). A four season panel survey exami...

  1. Reversible degradation in ITO-containing organic photovoltaics under concentrated sunlight

    NARCIS (Netherlands)

    Galagan, Y.O.; Mescheloff, A.; Veenstra, S.C.; Andriessen, H.A.J.M.; Katz, E.A.

    2015-01-01

    Stabilities of ITO-containing and ITO-free organic solar cells were investigated under simulated AM 1.5G illumination and under concentrated natural sunlight. In both cases ITO-free devices exhibit high stability, while devices containing ITO show degradation of their photovoltaic performance. The

  2. Sunlight-enhanced calcareous deposition on cathodic stainless steel in natural seawater

    Digital Repository Service at National Institute of Oceanography (India)

    Eashwar, M.; SathishKumar, P.; Ravishankar, R.; Subramanian, G.

    In replicate series of experiments in natural seawater, one in full darkness and the other in a 1:1 diurnal cycle with as little as 5 percent of natural solar illumination, sunlight promoted calcareous deposition on cathodic stainless steel surfaces...

  3. Colour Counts: Sunlight and Skin Type as Drivers of Vitamin D Deficiency at UK Latitudes.

    Science.gov (United States)

    Webb, Ann R; Kazantzidis, Andreas; Kift, Richard C; Farrar, Mark D; Wilkinson, Jack; Rhodes, Lesley E

    2018-04-07

    Sunlight exposure, with resulting cutaneous synthesis, is a major source of vitamin D for many, while dietary intake is low in modern diets. The constitutive pigment in skin determines skin type, observed as white, brown, or black skin. The melanin pigment absorbs ultraviolet radiation (UVR) and protects underlying skin from damage caused by UVR. It also reduces the UVR available for vitamin D synthesis in the skin. It has been shown that the white-skinned population of the UK are able to meet their vitamin D needs with short, daily lunchtime exposures to sunlight. We have followed the same methodology, based on a 10-year UK all-weather UVR climatology, observation (sun exposure, diet, vitamin D status), and UVR intervention studies with Fitzpatrick skin type V (brown) adults, to determine whether sunlight at UK latitudes could provide an adequate source of vitamin D for this section of the population. Results show that to meet vitamin D requirements, skin type V individuals in the UK need ~25 min daily sunlight at lunchtime, from March to September. This makes several assumptions, including that forearms and lower legs are exposed June-August; only exposing hands and face at this time is inadequate. For practical and cultural reasons, enhanced oral intake of vitamin D should be considered for this population.

  4. Tropospheric nitrogen dioxide inversions based on spectral measurements of scattered sunlight

    NARCIS (Netherlands)

    Vlemmix, T.

    2011-01-01

    This thesis describes the development of inversion methods for tropospheric nitrogen dioxide (NO2), based on ground based observations of scattered sunlight with themulti-axis differential optical absorption spectroscopy (MAX-DOAS) technique. NO2 is an atmospheric trace gas which, when present near

  5. HISTORY OF SUNLIGHT EXPOSURE IS A RISK FACTOR FOR AGE-RELATED MACULAR DEGENERATION

    NARCIS (Netherlands)

    Schick, T.; Ersoy, L.; Lechanteur, Y.T.; Saksens, N.T.; Hoyng, C.B.; Hollander, A.I. den; Kirchhof, B.; Fauser, S.

    2016-01-01

    PURPOSE: To evaluate effects of current and past sunlight exposure and iris color on early and late age-related macular degeneration (AMD). METHODS: Of 3,701 individuals from the EUGENDA database, 752 (20.3%) showed early AMD, 1,179 (31.9%) late AMD, and 1,770 (47.8%) were controls. Information

  6. Greenhouse Effect: Temperature of a Metal Sphere Surrounded by a Glass Shell and Heated by Sunlight

    Science.gov (United States)

    Nguyen, Phuc H.; Matzner, Richard A.

    2012-01-01

    We study the greenhouse effect on a model satellite consisting of a tungsten sphere surrounded by a thin spherical, concentric glass shell, with a small gap between the sphere and the shell. The system sits in vacuum and is heated by sunlight incident along the "z"-axis. This development is a generalization of the simple treatment of the…

  7. DNA damage by ethylbenzenehydroperoxide formed from carcinogenic ethylbenzene by sunlight irradiation

    International Nuclear Information System (INIS)

    Toda, Chitose; Uchida, Takafumi; Midorikawa, Kaoru; Murata, Mariko; Hiraku, Yusuke; Okamoto, Yoshinori; Ueda, Koji; Kojima, Nakao; Kawanishi, Shosuke

    2003-01-01

    Ethylbenzene, widely used in human life, is a non-mutagenic carcinogen. Sunlight-irradiated ethylbenzene caused DNA damage in the presence of Cu 2+ , but unirradiated ethylbenzene did not. A Cu + -specific chelator bathocuproine inhibited DNA damage and catalase showed a little inhibitory effect. The scopoletin assay revealed that peroxides and H 2 O 2 were formed in ethylbenzene exposed to sunlight. These results suggest that Cu + and alkoxyl radical mainly participate in DNA damage, and H 2 O 2 partially does. When catalase was added, DNA damage at thymine and cytosine was inhibited. Ethylbenzenehydroperoxide, identified by GC/MS analysis, induced the formation of 8-oxo-7,8-dihydro-2 ' -deoxyguanosine and caused DNA damage at consecutive guanines, as observed with cumenehydroperoxide. Equimolar concentrations of H 2 O 2 and acetophenone were produced by the sunlight-irradiation of 1-phenylethanol, a further degraded product of ethylbenzene. These results indicate a novel pathway that oxidative DNA damage induced by the peroxide and H 2 O 2 derived from sunlight-irradiated ethylbenzene may lead to expression of the carcinogenicity

  8. Colour Counts: Sunlight and Skin Type as Drivers of Vitamin D Deficiency at UK Latitudes

    Directory of Open Access Journals (Sweden)

    Ann R. Webb

    2018-04-01

    Full Text Available Sunlight exposure, with resulting cutaneous synthesis, is a major source of vitamin D for many, while dietary intake is low in modern diets. The constitutive pigment in skin determines skin type, observed as white, brown, or black skin. The melanin pigment absorbs ultraviolet radiation (UVR and protects underlying skin from damage caused by UVR. It also reduces the UVR available for vitamin D synthesis in the skin. It has been shown that the white-skinned population of the UK are able to meet their vitamin D needs with short, daily lunchtime exposures to sunlight. We have followed the same methodology, based on a 10-year UK all-weather UVR climatology, observation (sun exposure, diet, vitamin D status, and UVR intervention studies with Fitzpatrick skin type V (brown adults, to determine whether sunlight at UK latitudes could provide an adequate source of vitamin D for this section of the population. Results show that to meet vitamin D requirements, skin type V individuals in the UK need ~25 min daily sunlight at lunchtime, from March to September. This makes several assumptions, including that forearms and lower legs are exposed June–August; only exposing hands and face at this time is inadequate. For practical and cultural reasons, enhanced oral intake of vitamin D should be considered for this population.

  9. Plant Leaf Imaging using Time of Flight Camera under Sunlight, Shadow and Room Conditions

    DEFF Research Database (Denmark)

    Kazmi, Wajahat; Foix, Sergi; Alenya, Guillem

    2012-01-01

    In this article, we analyze the effects of ambient light on Time of Flight (ToF) depth imaging for a plant's leaf in sunlight, shadow and room conditions. ToF imaging is sensitive to ambient light and we try to find the best possible integration times (IT) for each condition. This is important in...

  10. Hybrid sunlight/LED illumination and renewable solar energy saving concepts for indoor lighting.

    Science.gov (United States)

    Tsuei, Chih-Hsuan; Sun, Wen-Shing; Kuo, Chien-Cheng

    2010-11-08

    A hybrid method for using sunlight and light-emitting diode (LED) illumination powered by renewable solar energy for indoor lighting is simulated and presented in this study. We can illuminate an indoor space and collect the solar energy using an optical switching system. When the system is turned off, the full spectrum of the sunlight is concentrated by a concentrator, to be absorbed by solar photovoltaic devices that provide the electricity to power the LEDs. When the system is turned on, the sunlight collected by the concentrator is split into visible and non-visible rays by a beam splitter. The visible rays pass through the light guide into a light box where it is mixed with LED light to ultimately provide uniform illumination by a diffuser. The non-visible rays are absorbed by the solar photovoltaic devices to provide electrical power for the LEDs. Simulation results show that the efficiency of the hybrid sunlight/LED illumination with the renewable solar energy saving design is better than that of LED and traditional lighting systems.

  11. Dose-Response Effect of Sunlight on Vitamin D2 Production in Agaricus bisporus Mushrooms

    DEFF Research Database (Denmark)

    Urbain, Paul; Jakobsen, Jette

    2015-01-01

    The dose response effect of UV-B irradiation from sunlight on vitamin D2 content of sliced Agaricus bisporus (white button mushroom) during the process of sun-drying was investigated.Real-time UV-B and UV-A data were obtained using a high-performance spectroradiometer. During the first hour...

  12. SnowCloud - a Framework to Predict Streamflow in Snowmelt-dominated Watersheds Using Cloud-based Computing

    Science.gov (United States)

    Sproles, E. A.; Crumley, R. L.; Nolin, A. W.; Mar, E.; Lopez-Moreno, J. J.

    2017-12-01

    Streamflow in snowy mountain regions is extraordinarily challenging to forecast, and prediction efforts are hampered by the lack of timely snow data—particularly in data sparse regions. SnowCloud is a prototype web-based framework that integrates remote sensing, cloud computing, interactive mapping tools, and a hydrologic model to offer a new paradigm for delivering key data to water resource managers. We tested the skill of SnowCloud to forecast monthly streamflow with one month lead time in three snow-dominated headwaters. These watersheds represent a range of precipitation/runoff schemes: the Río Elqui in northern Chile (200 mm/yr, entirely snowmelt); the John Day River, Oregon, USA (635 mm/yr, primarily snowmelt); and the Río Aragon in the northern Spain (850 mm/yr, snowmelt dominated). Model skill corresponded to snowpack contribution with Nash-Sutcliffe Efficiencies of 0.86, 0.52, and 0.21 respectively. SnowCloud does not require the user to possess advanced programming skills or proprietary software. We access NASA's MOD10A1 snow cover product to calculate the snow metrics globally using Google Earth Engine's geospatial analysis and cloud computing service. The analytics and forecast tools are provided through a web-based portal that requires only internet access and minimal training. To test the efficacy of SnowCloud we provided the tools and a series of tutorials in English and Spanish to water resource managers in Chile, Spain, and the United States. Participants assessed their user experience and provided feedback, and the results of our multi-cultural assessment are also presented. While our results focus on SnowCloud, they outline methods to develop cloud-based tools that function effectively across cultures and languages. Our approach also addresses the primary challenges of science-based computing; human resource limitations, infrastructure costs, and expensive proprietary software. These challenges are particularly problematic in developing

  13. Sunlight exposure or vitamin D supplementation for vitamin D-deficient non-western immigrants: a randomized clinical trial

    NARCIS (Netherlands)

    Wicherts, I.S.; Boeke, A.J.P.; van der Meer, I.M.; van Schoor, N.M.; Knol, D.L.; Lips, P.T.A.M.

    2011-01-01

    Summary: Vitamin D deficiency is very common in non-western immigrants. In this randomized clinical trial, vitamin D 800 IU/day or 100,000 IU/3 months were compared with advised sunlight exposure. Vitamin D supplementation was more effective than advised sunlight exposure in improving vitamin D

  14. IS THERE A LINK BETWEEN SUNLIGHT EXPOSURE AND 25-HYDROXYVITAMIN D DEFICIENCY IN CHRONIC KIDNEY DISEASE PATIENTS?

    Directory of Open Access Journals (Sweden)

    Angela Yee-Moon Wang

    2012-06-01

    In conclusion, our study confirmed an extremely high prevalence of vitamin D deficiency and an important association between outdoor sunlight exposure and 25(OHD deficiency in Chinese stage 3-5 CKD patients. Further study is needed to determine whether increasing daily outdoor sunlight exposure may represent a cost-free treatment for correcting nutritional 25(OHD deficiency in the CKD population.

  15. Influence of snowpack and melt energy heterogeneity on snow cover depletion and snowmelt runoff simulation in a cold mountain environment

    Science.gov (United States)

    DeBeer, Chris M.; Pomeroy, John W.

    2017-10-01

    The spatial heterogeneity of mountain snow cover and ablation is important in controlling patterns of snow cover depletion (SCD), meltwater production, and runoff, yet is not well-represented in most large-scale hydrological models and land surface schemes. Analyses were conducted in this study to examine the influence of various representations of snow cover and melt energy heterogeneity on both simulated SCD and stream discharge from a small alpine basin in the Canadian Rocky Mountains. Simulations were performed using the Cold Regions Hydrological Model (CRHM), where point-scale snowmelt computations were made using a snowpack energy balance formulation and applied to spatial frequency distributions of snow water equivalent (SWE) on individual slope-, aspect-, and landcover-based hydrological response units (HRUs) in the basin. Hydrological routines were added to represent the vertical and lateral transfers of water through the basin and channel system. From previous studies it is understood that the heterogeneity of late winter SWE is a primary control on patterns of SCD. The analyses here showed that spatial variation in applied melt energy, mainly due to differences in net radiation, has an important influence on SCD at multiple scales and basin discharge, and cannot be neglected without serious error in the prediction of these variables. A single basin SWE distribution using the basin-wide mean SWE (SWE ‾) and coefficient of variation (CV; standard deviation/mean) was found to represent the fine-scale spatial heterogeneity of SWE sufficiently well. Simulations that accounted for differences in (SWE ‾) among HRUs but neglected the sub-HRU heterogeneity of SWE were found to yield similar discharge results as simulations that included this heterogeneity, while SCD was poorly represented, even at the basin level. Finally, applying point-scale snowmelt computations based on a single SWE depth for each HRU (thereby neglecting spatial differences in internal

  16. Relationship Between Satellite-Derived Snow Cover and Snowmelt-Runoff Timing in the Wind River Range, Wyoming

    Science.gov (United States)

    Hall, Dorothy K.; Foster, James L.; DiGirolamo, Nicolo E.; Riggs, George A.

    2010-01-01

    MODIS-derived snow cover measured on 30 April in any given year explains approximately 89 % of the variance in stream discharge for maximum monthly streamflow in that year. Observed changes in streamflow appear to be related to increasing maximum air temperatures over the last four decades causing lower spring snow-cover extent. The majority (>70%) of the water supply in the western United States comes from snowmelt, thus analysis of the declining spring snowpack (and resulting declining stream discharge) has important implications for streamflow management in the drought-prone western U.S.

  17. Visual performance with sport-tinted contact lenses in natural sunlight.

    Science.gov (United States)

    Erickson, Graham B; Horn, Fraser C; Barney, Tyler; Pexton, Brett; Baird, Richard Y

    2009-05-01

    The use of tinted and clear contact lenses (CLs) in all aspects of life is becoming a more popular occurrence, particularly in athletic activities. This study broadens previous research regarding performance-tinted CLs and their effects on measures of visual performance. Thirty-three subjects (14 male, 19 female) were fitted with clear B&L Optima 38, 50% visible light transmission Amber and 36% visible light transmission Gray-Green Nike Maxsight CLs in an individualized randomized sequence. Subjects were dark-adapted with welding goggles before testing and in between subtests involving a Bailey-Lovie chart and the Haynes Distance Rock test. The sequence of testing was repeated for each lens modality. The Amber and Gray-Green lenses enabled subjects to recover vision faster in bright sunlight compared with clear lenses. Also, subjects were able to achieve better visual recognition in bright sunlight when compared with clear lenses. Additionally, the lenses allowed the subjects to alternate fixation between a bright and shaded target at a more rapid rate in bright sunlight as compared with clear lenses. Subjects preferred both the Amber and Gray-Green lenses over clear lenses in the bright and shadowed target conditions. The results of the current study show that Maxsight Amber and Gray-Green lenses provide better contrast discrimination in bright sunlight, better contrast discrimination when alternating between bright and shaded target conditions, better speed of visual recovery in bright sunlight, and better overall visual performance in bright and shaded target conditions compared with clear lenses.

  18. Photosynthesis, photoprotection, and growth of shade-tolerant tropical tree seedlings under full sunlight.

    Science.gov (United States)

    Krause, G Heinrich; Winter, Klaus; Matsubara, Shizue; Krause, Barbara; Jahns, Peter; Virgo, Aurelio; Aranda, Jorge; García, Milton

    2012-09-01

    High solar radiation in the tropics is known to cause transient reduction in photosystem II (PSII) efficiency and CO(2) assimilation in sun-exposed leaves, but little is known how these responses affect the actual growth performance of tropical plants. The present study addresses this question. Seedlings of five woody neotropical forest species were cultivated under full sunlight and shaded conditions. In full sunlight, strong photoinhibition of PSII at midday was documented for the late-successional tree species Ormosia macrocalyx and Tetragastris panamensis and the understory/forest gap species, Piper reticulatum. In leaves of O. macrocalyx, PSII inhibition was accompanied by substantial midday depression of net CO(2) assimilation. Leaves of all species had increased pools of violaxanthin-cycle pigments. Other features of photoacclimation, such as increased Chl a/b ratio and contents of lutein, β-carotene and tocopherol varied. High light caused strong increase of tocopherol in leaves of T. panamensis and another late-successional species, Virola surinamensis. O. macrocalyx had low contents of tocopherol and UV-absorbing substances. Under full sunlight, biomass accumulation was not reduced in seedlings of T. panamensis, P. reticulatum, and V. surinamensis, but O. macrocalyx exhibited substantial growth inhibition. In the highly shade-tolerant understory species Psychotria marginata, full sunlight caused strongly reduced growth of most individuals. However, some plants showed relatively high growth rates under full sun approaching those of seedlings at 40 % ambient irradiance. It is concluded that shade-tolerant tropical tree seedlings can achieve efficient photoacclimation and high growth rates in full sunlight.

  19. Sunlight exposure during leisure activities and risk of prostate cancer in Montréal, Canada, 2005-2009.

    Science.gov (United States)

    Yu, Jennifer; Lavoué, Jérôme; Parent, Marie-Élise

    2014-07-28

    Prostate cancer (PCa) is the leading cause of cancer in men in many developed countries, but no modifiable risk factors have been identified. A handful of analytical studies have suggested a possible etiological role for sunlight exposure. We report here on the association between leisure-time sunlight exposure during adulthood and PCa risk in the context of a population-based case-control study. In all, 1,904 PCa cases were ascertained across Montreal French hospitals between 2005 and 2009. Concurrently, 1,962 population controls, frequency matched to cases by age (±5 years), were selected from the electoral list for French-speakers in Greater Montreal. Interviews elicited the frequency of engagement in any leisure activity during adulthood. This was used to derive cumulative sunlight exposure indices: a cumulative number of leisure activities events entailing sunlight exposure and a cumulative duration of sunlight exposure during leisure activities. Unconditional logistic regression was conducted to yield odds ratios (OR) and 95% confidence intervals (CI) for estimating the association between sunlight exposure indices and PCa risk, adjusting for age, ancestry, family history of PCa, PCa screening, education, solar protection, body mass index and physical activity. Compared with men in the upper quartile category for the number of sunlight exposure events, men never exposed during leisure time had an OR of 1.32 (95% CI: 0.82-2.14). ORs were 1.11, 0.91 and 1.00 for the first to the third quartiles of exposure, respectively. Similar results were observed for cumulative duration of exposure to sunlight, and by PCa aggressiveness. These findings provide little evidence of an association between sunlight exposure during leisure-time and PCa risk. Men with no sunlight exposure appeared at somewhat higher risks but none of the estimates achieved statistical significance.

  20. Soil moisture response to snowmelt and rainfall in a Sierra Nevada mixed-conifer forest

    Science.gov (United States)

    Roger C. Bales; Jan W. Hopmans; Anthony T. O’Geen; Matthew Meadows; Peter C. Hartsough; Peter Kirchner; Carolyn T. Hunsaker; Dylan. Beaudette

    2011-01-01

    Using data from a water-balance instrument cluster with spatially distributed sensors we determined the magnitude and within-catchment variability of components of the catchment-scale water balance, focusing on the relationship of seasonal evapotranspiration to changes in snowpack and soil moisture storage. Co-located, continuous snow depth and soil moisture...

  1. Enhancing Seasonal Water Outlooks: Needs and Opportunities in the Critical Runoff Season

    Science.gov (United States)

    Ray, A. J.; Barsugli, J. J.; Yocum, H.; Stokes, M.; Miskus, D.

    2017-12-01

    The runoff season is a critical period for the management of water supply in the western U.S., where in many places over 70% of the annual runoff occurs in the snowmelt period. Managing not only the volume, but the intra-seasonal timing of the runoff is important for optimizing storage, as well as achieving other goals such as mitigating flood risk, and providing peak flows for riparian habitat management, for example, for endangered species. Western river forecast centers produce volume forecasts for western reservoirs that are key input into many water supply decisions, and also short term river forecasts out to 10 days. The early volume forecasts each year typically begin in December, and are updated throughout the winter and into the runoff season (April-July for many areas, but varies). This presentation will discuss opportunities for enhancing this existing suite of RFC water outlooks, including the needs for and potential use for "intraseasonal" products beyond those provided by the Ensemble Streamflow Prediction system and the volume forecasts. While precipitation outlooks have little skill for many areas and seasons, and may not contribute significantly to the outlook, late winter and spring temperature forecasts have meaningful skill in certain areas and sub-seasonal to seasonal time scales. This current skill in CPC temperature outlooks is an opportunity to translate these products into information about the snowpack and potential runoff timing, even where the skill in precipitation is low. Temperature is important for whether precipitation falls as snow or rain, which is critical for streamflow forecasts, especially in the melt season in snowpack-dependent watersheds. There is a need for better outlooks of the evolution of snowpack, conditions influencing the April-July runoff, and the timing of spring peak or shape of the spring hydrograph. The presentation will also discuss a our work with stakeholders of the River Forecast Centers and the NIDIS

  2. Impacts of Non-Stationarity in Climate on Flood Intensity-Duration-Frequency: Case Studies in Mountainous Areas with Snowmelt

    Science.gov (United States)

    Hou, Z.; Ren, H.; Sun, N.; Leung, L. R.; Liu, Y.; Coleman, A. M.; Skaggs, R.; Wigmosta, M. S.

    2017-12-01

    Hydrologic engineering design usually involves intensity-duration-frequency (IDF) analysis for calculating runoff from a design storm of specified precipitation frequency and duration using event-based hydrologic rainfall-runoff models. Traditionally, the procedure assumes climate stationarity and neglects snowmelt-driven runoff contribution to floods. In this study, we used high resolution climate simulations to provide inputs to the physics-based Distributed Hydrology Soil and Vegetation Model (DHSVM) to determine the spatially distributed precipitation and snowmelt available for runoff. Climate model outputs were extracted around different mountainous field sites in Colorado and California. IDF curves were generated at each numerical grid of DHSVM based on the simulated precipitation, temperature, and available water for runoff. Quantitative evaluation of trending and stationarity tests were conducted to identify (quasi-)stationary time periods for reliable IDF analysis. The impact of stationarity was evaluated by comparing the derived IDF attributes with respect to time windows of different length and level of stationarity. Spatial mapping of event return-period was performed for various design storms, and spatial mapping of event intensity was performed for given duration and return periods. IDF characteristics were systematically compared (historical vs RCP4.5 vs RCP8.5) using annual maximum series vs partial duration series data with the goal of providing reliable IDF analyses to support hydrologic engineering design.

  3. Assessing the response of Emerald Lake, an alpine watershed in Sequoia National Park, California, to acidification during snowmelt by using a simple hydrochemical model

    International Nuclear Information System (INIS)

    Hooper, R.P.; West, C.T.; Peters, N.E.

    1990-01-01

    A sparsely parameterized hydrochemical model has been developed by using data from Emerald Lake watershed, which is a 120-ha alpine catchment in Sequoia National Park, California. Greater than 90% of the precipitation to this watershed is snow; hence, snowmelt is the dominant hydrologic event. A model which uses a single alkalinity-generating mechanism, primary mineral weathering, was able to capture the pattern of solute concentrations in surface waters during snowmelt. An empirical representation of the weathering reaction, which is based on rock weathering stoichiometry and which uses discharge as a measure of residence time, was included in the model. Results of the model indicate that current deposition levels would have to be increased between three-fold and eight-fold to exhaust the alkalinity of the lake during snowmelt if their is a mild acidic pulse in the stream at the beginning of snowmelt as was observed during the study period. The acidic pulse in the inflow stream at the onset of snowmelt was less pronounced than acidic pulses observed in the meltwater draining the snowpack at a point using snow lysimeters or in the laboratory. Sulfate concentrations in the stream water were the most constant; chloride and nitrate concentrations increased slightly at the beginning of snowmelt. Additional field work is required to resolve whether an acidic meltwater pulse occurs over a large area as well as at a point or whether, due to physical and chemical processes within the snowpack, the acidic meltwater pulse is attenuated at the catchment scale. The modest data requirements of the model permit its applications to other alpine watersheds that are much less intensively studied than Emerald Lake watershed

  4. Application and Evaluation of a Snowmelt Runoff Model in the Tamor River Basin, Eastern Himalaya Using a Markov Chain Monte Carlo (MCMC) Data Assimilation Approach

    Science.gov (United States)

    Panday, Prajjwal K.; Williams, Christopher A.; Frey, Karen E.; Brown, Molly E.

    2013-01-01

    Previous studies have drawn attention to substantial hydrological changes taking place in mountainous watersheds where hydrology is dominated by cryospheric processes. Modelling is an important tool for understanding these changes but is particularly challenging in mountainous terrain owing to scarcity of ground observations and uncertainty of model parameters across space and time. This study utilizes a Markov Chain Monte Carlo data assimilation approach to examine and evaluate the performance of a conceptual, degree-day snowmelt runoff model applied in the Tamor River basin in the eastern Nepalese Himalaya. The snowmelt runoff model is calibrated using daily streamflow from 2002 to 2006 with fairly high accuracy (average Nash-Sutcliffe metric approx. 0.84, annual volume bias runoff in the Tamor River basin for the 2002-2006 period is estimated to be 29.7+/-2.9% (which includes 4.2+/-0.9% from snowfall that promptly melts), whereas 70.3+/-2.6% is attributed to contributions from rainfall. On average, the elevation zone in the 4000-5500m range contributes the most to basin runoff, averaging 56.9+/-3.6% of all snowmelt input and 28.9+/-1.1% of all rainfall input to runoff. Model simulated streamflow using an interpolated precipitation data set decreases the fractional contribution from rainfall versus snowmelt compared with simulations using observed station precipitation. Model experiments indicate that the hydrograph itself does not constrain estimates of snowmelt versus rainfall contributions to total outflow but that this derives from the degree-day melting model. Lastly, we demonstrate that the data assimilation approach is useful for quantifying and reducing uncertainty related to model parameters and thus provides uncertainty bounds on snowmelt and rainfall contributions in such mountainous watersheds.

  5. Biodegradation and photooxidation of crude oil under natural sunlight in the northern Gulf of Mexico

    Science.gov (United States)

    Bacosa, H. P.; Erdner, D.; Liu, Z.

    2016-02-01

    An enormous amount of oil was observed in the deep and surface waters of the northern Gulf of Mexico (nGoM) following the Deepwater Horizon (DWH) spill. While the oil degradation and bacterial communities in the deep-sea plume have been widely investigated, the effect of sunlight on oil and bacterial assemblages in surface waters have received less attention. In this study, we amended surface water collected near the DWH site with crude oil and/or Corexit dispersant and incubated under natural sunlight in the nGoM for 36 d in summer of 2013. The residual alkanes, polycyclic aromatic hydrocarbons (PAHs), and alkalyted PAHs were analyzed by GC-MS, and bacterial community was determined via pyrosequencing. The results show that n-alkane biodegradation rate constants (first order) were ca. ten-fold higher than the photooxidation rate constants. While biodegradation was characterized by a lag phase, photooxidation rate constants for the 2-3 ring and 4-5 ring PAHs, were 0.08-0.98 day-1 and 0.01-0.07 day-1, respectively. Compared to biodegradation, photooxidation increased the transformation of 4-5 ring PAHs by 70% and 3-4 ring alkylated PAHs by 36%. Sunlight significantly reduced bacterial diversity and a driver of shifts in bacterial community structure in oil and Corexit treatments. In amended treatments, sunlight increased the relative abundances of Alteromonas, Marinobacter, Labrenzia, Sandarakinotalea, Halomonas and Bartonella, while the dark treatments enriched Thalassobius, Winogradskyella, Alcanivorax, Formosa, Eubacterium, Erythrobacter, Natronocella, and Pseudomonas. This suggests that different bacteria are degrading the hydrocarbons in the dark and under light exposure. In a follow up study using DNA-Stable isotope probing (SIP), we identified the alkane and PAH degraders using 13C-labeled hexadecane and phenanthrene, respectively. The results of metagenomic and metatranscriptomic analyses in the light and dark incubations will be presented. For the first

  6. Effect of the precipitation interpolation method on the performance of a snowmelt runoff model

    Science.gov (United States)

    Jacquin, Alexandra

    2014-05-01

    Uncertainties on the spatial distribution of precipitation seriously affect the reliability of the discharge estimates produced by watershed models. Although there is abundant research evaluating the goodness of fit of precipitation estimates obtained with different gauge interpolation methods, few studies have focused on the influence of the interpolation strategy on the response of watershed models. The relevance of this choice may be even greater in the case of mountain catchments, because of the influence of orography on precipitation. This study evaluates the effect of the precipitation interpolation method on the performance of conceptual type snowmelt runoff models. The HBV Light model version 4.0.0.2, operating at daily time steps, is used as a case study. The model is applied in Aconcagua at Chacabuquito catchment, located in the Andes Mountains of Central Chile. The catchment's area is 2110[Km2] and elevation ranges from 950[m.a.s.l.] to 5930[m.a.s.l.] The local meteorological network is sparse, with all precipitation gauges located below 3000[m.a.s.l.] Precipitation amounts corresponding to different elevation zones are estimated through areal averaging of precipitation fields interpolated from gauge data. Interpolation methods applied include kriging with external drift (KED), optimal interpolation method (OIM), Thiessen polygons (TP), multiquadratic functions fitting (MFF) and inverse distance weighting (IDW). Both KED and OIM are able to account for the existence of a spatial trend in the expectation of precipitation. By contrast, TP, MFF and IDW, traditional methods widely used in engineering hydrology, cannot explicitly incorporate this information. Preliminary analysis confirmed that these methods notably underestimate precipitation in the study catchment, while KED and OIM are able to reduce the bias; this analysis also revealed that OIM provides more reliable estimations than KED in this region. Using input precipitation obtained by each method

  7. Effect of precipitation spatial distribution uncertainty on the uncertainty bounds of a snowmelt runoff model output

    Science.gov (United States)

    Jacquin, A. P.

    2012-04-01

    This study analyses the effect of precipitation spatial distribution uncertainty on the uncertainty bounds of a snowmelt runoff model's discharge estimates. Prediction uncertainty bounds are derived using the Generalized Likelihood Uncertainty Estimation (GLUE) methodology. The model analysed is a conceptual watershed model operating at a monthly time step. The model divides the catchment into five elevation zones, where the fifth zone corresponds to the catchment glaciers. Precipitation amounts at each elevation zone i are estimated as the product between observed precipitation (at a single station within the catchment) and a precipitation factor FPi. Thus, these factors provide a simplified representation of the spatial variation of precipitation, specifically the shape of the functional relationship between precipitation and height. In the absence of information about appropriate values of the precipitation factors FPi, these are estimated through standard calibration procedures. The catchment case study is Aconcagua River at Chacabuquito, located in the Andean region of Central Chile. Monte Carlo samples of the model output are obtained by randomly varying the model parameters within their feasible ranges. In the first experiment, the precipitation factors FPi are considered unknown and thus included in the sampling process. The total number of unknown parameters in this case is 16. In the second experiment, precipitation factors FPi are estimated a priori, by means of a long term water balance between observed discharge at the catchment outlet, evapotranspiration estimates and observed precipitation. In this case, the number of unknown parameters reduces to 11. The feasible ranges assigned to the precipitation factors in the first experiment are slightly wider than the range of fixed precipitation factors used in the second experiment. The mean squared error of the Box-Cox transformed discharge during the calibration period is used for the evaluation of the

  8. Snowmelt in a High Latitude Mountain Catchment: Effect of Vegetation Cover and Elevation

    Science.gov (United States)

    Pomeroy, J. W.; Essery, R. L.; Ellis, C. R.; Hedstrom, N. R.; Janowicz, R.; Granger, R. J.

    2004-12-01

    The energetics and mass balance of snowpacks in the premelt and melt period were compared from three elevation bands in a high latitude mountain catchment, Wolf Creek Research Basin, Yukon. Elevation is strongly correlated with vegetation cover and in this case the three elevation bands (low, middle, high) correspond to mature spruce forest, dense shrub tundra and sparse tundra (alpine). Measurements of radiation, ground heat flux, snow depth, snowfall, air temperature, wind speed were made on a half-hourly basis at the three elevations for a 10 year period. Sondes provided vertical gradients of air temperature, humidity, wind speed and air pressure. Snow depth and density surveys were conducted monthly. Comparisons of wind speed, air temperature and humidity at three elevations show that the expected elevational gradients in the free atmosphere were slightly enhanced just above the surface canopies, but that the climate at the snow surface was further influenced by complex canopy effects. Premelt snow accumulation was strongly affected by intercepted snow in the forest and blowing snow sublimation in the sparse tundra but not by the small elevational gradients in snowfall. As a result the maximum premelt SWE was found in the mid-elevation shrub tundra and was roughly double that of the sparse tundra or forest. Minimum variability of SWE was observed in the forest and shrub tundra (CV=0.25) while in the sparse tundra variability doubled (CV=0.5). Snowmelt was influenced by differences in premelt accumulation as well as differences in the net energy fluxes to snow. Elevation had a strong effect on the initiation of melt with the forest melt starting on average 16 days before the shrub tundra and 19 days before the sparse tundra. Mean melt rates showed a maximum in middle elevations and increased from 860 kJ/day in the forest to 1460 kJ/day in the sparse tundra and 2730 kJ/day in the shrub tundra. The forest canopy reduced melt while the shrub canopy enhanced it

  9. Modeling of Future Changes in Seasonal Snowpack and Impacts on Summer Low Flows in Alpine Catchments

    Science.gov (United States)

    Jenicek, Michal; Seibert, Jan; Staudinger, Maria

    2018-01-01

    It is expected that an increasing proportion of the precipitation will fall as rain in alpine catchments in the future. Consequently, snow storage is expected to decrease, which, together with changes in snowmelt rates and timing, might cause reductions in spring and summer low flows. The objectives of this study were (1) to simulate the effect of changing snow storage on low flows during the warm seasons and (2) to relate drought sensitivity to the simulated snow storage changes at different elevations. The Swiss Climate Change Scenarios 2011 data set was used to derive future changes in air temperature and precipitation. A typical bucket-type catchment model, HBV-light, was applied to 14 mountain catchments in Switzerland to simulate streamflow and snow in the reference period and three future periods. The largest relative decrease in annual maximum SWE was simulated for elevations below 2,200 m a.s.l. (60-75% for the period 2070-2099) and the snowmelt season shifted by up to 4 weeks earlier. The relative decrease in spring and summer minimum runoff that was caused by the relative decrease in maximum SWE (i.e., elasticity), reached 40-90% in most of catchments for the reference period and decreased for the future periods. This decreasing elasticity indicated that the effect of snow on summer low flows is reduced in the future. The fraction of snowmelt runoff in summer decreased by more than 50% at the highest elevations and almost disappeared at the lowest elevations. This might have large implications on water availability during the summer.

  10. Improved Flexible Transparent Conductive Electrodes based on Silver Nanowire Networks by a Simple Sunlight Illumination Approach

    Science.gov (United States)

    Kou, Pengfei; Yang, Liu; Chang, Cheng; He, Sailing

    2017-01-01

    Silver nanowire (Ag NW) networks have attracted wide attention as transparent electrodes for emerging flexible optoelectronics. However, the sheet resistance is greatly limited by large wire-to-wire contact resistances. Here, we propose a simple sunlight illumination approach to remarkably improve their electrical conductivity without any significant degradation of the light transmittance. Because the power density is extremely low (0.1 W/cm2, 1-Sun), only slight welding between Ag NWs has been observed. Despite this, a sheet resistance of solar concentrations. Due to the reduced resistance, high-performance transparent film heaters as well as efficient defrosters have been demonstrated, which are superior to the previously-reported Ag NW based film heaters. Since the sunlight is environmentally friendly and easily available, sophisticated or expensive facilities are not necessary. Our findings are particularly meaningful and show enormous potential for outdoor applications. PMID:28169343

  11. Photodegradation of 2,4-Dichlorophenol in Aqueous Systems under Simulated and Natural Sunlight

    Directory of Open Access Journals (Sweden)

    Dorota Gryglik

    2016-01-01

    Full Text Available The work presents results of studies on 2,4-dichlorophenol (2,4-DCP degradation in aqueous solutions using photochemically initiated processes by simulated and natural sunlight. A number of possible substrate photodegradation routes were investigated, by both direct photolysis and photosensitized oxidation process. The major role of singlet oxygen in 2,4-DCP photodegradation was proved. Rose Bengal and derivatives of porphine and phthalocyanine were used as sensitizers. The influences of various process parameters on the reaction rate were investigated. On the basis of experimental data reaction rate constants of 2,4-DCP photosensitized oxidation were determined. The possibility of using natural sunlight to degrade 2,4-DCP in water in the middle latitudes was stated. The acute toxicity bioassay was conducted with the marine bacterium Vibrio fischeri as a bioluminescent indicator. The obtained results encourage further research on this process.

  12. Effects of UV, sunlight and X-ray radiation on quiescent human cells in culture

    International Nuclear Information System (INIS)

    Kantor, G.J.

    1986-01-01

    Nondividing human diploid fibroblasts (HDF) in culture have been used to study the effect on cell lethality of ultraviolet light, natural sunlight and X-rays. A lethal effect is defined as cellular degeneration, loss from the culture and inability to exclude vital strains. Far- and mid-UV have a readily observable lethal effect (cell loss), with DNA and DNA damage as the critical target and critical damage respectively. In part, natural sunlight kills cells by a similar mechanism but has an additional lethal effect at longer exposure times. This additional effect is expressed by the retention of the dead cells in culture, in contrast to the UV-induced promotion of cell degeneration and loss. Relatively large doses of X-rays that destroy proliferative capacity, have no detectable lethal effect on the maintenance of non-dividing cells. The biological response of nondividing HDF to radiations from different parts of the electromagnetic spectrum is dissimilar. (author)

  13. Sunlight reflection off the spacecraft with a solar sail on the surface of mars

    Science.gov (United States)

    Starinova, O. L.; Rozhkov, M. A.; Gorbunova, I. V.

    2018-05-01

    Modern technologies make it possible to fulfill many projects in the field of space exploration. One such project is the colonization of Mars and providing favorable conditions for living on it. Authors propose principles of functioning of the spacecraft with a solar sail, intended to create a thermal and light spot in a predetermined area of the Martian surface. This additional illumination can maintain and support certain climatic conditions on a small area where a Mars base could be located. This paper investigate the possibility of the spacecraft continuously reflect the sunlight off the solar sail on the small area of the Mars surface. The mathematical motion model in such condition of the solar sail's orientation is considered and used for motion simulation session. Moreover, the analysis of this motion is performed. Thus, were obtained parameters of the synchronic non-Keplerian orbit and spacecraft construction. In addition, were given recommendations for further applying satellites to reflect the sunlight on a planet's surface.

  14. Reflected Sunlight Reduction and Characterization for a Deep-Space Optical Receiver Antenna (DSORA)

    Science.gov (United States)

    Clymer, B. D.

    1990-01-01

    A baffle system for the elimination of first-order specular and diffuse reflection of sunlight from the sunshade of a deep-space optical receiver telescope is presented. This baffle system consists of rings of 0.5cm blades spaced 2.5 cm apart on the walls of GO hexagonal sunshade tubes that combine to form the telescope sunshade. The shadow cast by the blades, walls, and rims of the tubes prevent all first-order reflections of direct sunlight from reaching the primary mirror of the telescope. A reflection model of the sunshade without baffles is also presented for comparison. Since manufacturers of absorbing surfaces do not measure data near grazing incidence, the reflection properties at anticipated angles of incidence must be characterized. A description of reflection from matte surfaces in term of bidirectional reflection distribution function (BRDF) is presented along with a discussion of measuring BRDF near grazing incidence.

  15. Photolysis of polycyclic aromatic hydrocarbons adsorbed on spruce [Picea abies (L.) Karst.] needles under sunlight irradiation

    International Nuclear Information System (INIS)

    Niu Junfeng; Chen Jingwen; Martens, D.; Quan Xie; Yang Fenglin; Kettrup, A.; Schramm, K.-W.

    2003-01-01

    Photolysis of PAHs on surfaces may determine their ultimate fate in the environment. - Photolysis of polycyclic aromatic hydrocarbons (PAHs) sorbed on surfaces of spruce [Picea abies (L.) Karst.] needles under sunlight irradiation was investigated. PAHs were produced by combustion of polyvinyl chloride (PVC), wood, high-density polyethylene (HDPE), and styrene in a stove. The factors of sunlight irradiation on the surfaces of spruce needles were taken into consideration when investigating the kinetic parameters. The photolysis of the 18 PAHs under study follows first-order kinetics. The photolysis half-lives range from 15 h for dibenzo(a,h)anthracene to 75 h for phenanthrene. Photolysis of some PAHs on surfaces of spruce needles may play an important role on the fate of PAHs in the environment

  16. Seasonal contrast in the surface energy balance of the Sahel

    Science.gov (United States)

    Miller, R. L.; Slingo, A.; Barnard, J. C.; Kassianov, E.

    2009-07-01

    Over much of the world, heating of the surface by sunlight is balanced predominately by evaporative cooling. However, at the Atmospheric Radiation Measurement (ARM) Mobile Facility (AMF) in Niamey, Niger, evaporation makes a significant contribution to the surface energy balance only at the height of the rainy season, when precipitation has replenished the reservoir of soil moisture. The AMF was placed at Niamey from late 2005 to early 2007 to provide measurements of surface fluxes in coordination with geostationary satellite retrievals of radiative fluxes at the top of the atmosphere, as part of the RADAGAST experiment to calculate atmospheric radiative divergence. We use observations at the mobile facility to investigate how the surface adjusts to radiative forcing throughout the year. The surface response to solar heating varies with changes in atmospheric water vapor associated with the seasonal reversal of the West African monsoon, which modulates the greenhouse effect and the ability of the surface to radiate thermal energy directly to space. During the dry season, sunlight is balanced mainly by longwave radiation and the turbulent flux of sensible heat. The ability of longwave radiation to cool the surface drops after the onset of southwesterly surface winds at Niamey, when moist, oceanic air flows onshore, increasing local column moisture and atmospheric opacity. Following the onset of southwesterly flow, evaporation remains limited by the supply of moisture from precipitation. By the height of the rainy season, however, sufficient precipitation has accumulated that evaporation is controlled by incident sunlight, and radiative forcing of the surface is balanced comparably by the latent, sensible, and longwave fluxes. Evaporation increases with the leaf area index, suggesting that plants are a significant source of atmospheric moisture and may tap moisture stored beneath the surface that accumulated during a previous rainy season. Surface radiative forcing

  17. Converting sunlight into red light in fluorosilicate glass for amorphous silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Ming, Chengguo, E-mail: mingchengguo1978@163.com [Physics Department, School of Sciences, Tianjin University of Science & Technology, Tianjin 300457 (China); Song, Feng [Photonics Center, College of Physical Science, Nankai University, Tianjin 300071 (China); Ren, Xiaobin [Physics Department, School of Sciences, Tianjin University of Science & Technology, Tianjin 300457 (China); Yuan, Fengying; Qin, Yueting [Physics Department, School of Sciences, Tianjin University of Science & Technology, Tianjin 300457 (China); Photonics Center, College of Physical Science, Nankai University, Tianjin 300071 (China); An, Liqun; Cai, Yuanxue [Physics Department, School of Sciences, Tianjin University of Science & Technology, Tianjin 300457 (China)

    2017-03-15

    Fluorosilicate glass was prepared by high-temperature melting method to explore highly efficient luminescence materials for amorphous silicon solar cells. Absorption, excitation and emission spectra of the glass were measured. The optical characters of the glass were discussed in details. The glass can efficiently convert sunlight into red light. Our glass can be applied to amorphous silicon solar cells as a converter of solar spectrum.

  18. Carcinogenic effect of sequential artificial sunlight and UV-A irradiation in hairless mice. Consequences for solarium 'therapy'

    International Nuclear Information System (INIS)

    Staberg, B.; Wulf, H.C.; Poulsen, T.; Klemp, P.; Brodthagen, H.

    1983-01-01

    The carcinogenic effect of artificial UV sunlight followed by UV-A irradiation in human solaria doses has been studied with the use of the hairless mouse as an animal model. Artificial sunlight exposure alone induced only a moderate skin tumor incidence (animals with at least one tumor) of 0.15 after one year, and UV-A irradiation alone induced no tumor formation. However, the combination of artificial sunlight exposure and subsequent UV-A irradiation significantly increased the tumor incidence to 0.72. We conclude that, in humans, tanning with UV-A for cosmetic purposes may not be an innocuous procedure

  19. The Photocatalytic Activity of TiO2-Zeolite Composite for Degradation of Dye Using Synthetic UV and Jeddah Sunlight

    Directory of Open Access Journals (Sweden)

    Laila M. Al-Harbi

    2015-01-01

    Full Text Available In this research different composites of impregnated TiO2 with LTA or FAU zeolites were used as different weight% ratio for photodegradation of organic dye. Normal laboratory UV-lamps were used as a source of UV irradiation. In addition a setup of system of mirrors was used to collect real Jeddah sunlight. A comparison of UV and real sunlight photodegradation activity showed that the real sunlight enhances new centers of active sites exhibiting higher catalytic activity than that of UV irradiated samples.

  20. Photolytic debromination pathway of polybrominated diphenyl ethers in hexane by sunlight

    International Nuclear Information System (INIS)

    Wei, Hua; Zou, Yonghong; Li, An; Christensen, Erik R.; Rockne, Karl J.

    2013-01-01

    The objective of this work is to identify the photolytic debromination pathways of polybrominated diphenyl ethers (PBDEs). Thirteen PBDEs (BDEs 209, 208, 207, 206, 196, 183, 154, 153, 100, 99, 85, 47 and 28) in hexane were individually exposed to sunlight for up to 64 h. A total of 180 PBDEs were screened and 74 BDE debromination products were detected. The disappearance rate constant increased exponentially with increasing number of bromines. While no evident difference in debromination preference among ortho, meta and para bromines was found for heavier congeners, the vulnerability rank order was meta ≥ ortho > para for the lighter congeners (≤8 Br). The total molar mass of PBDEs continuously decreased during sunlight exposure, indicating PBDEs were transformed to non-PBDE compounds. A stochastic least squares debromination pathway model was developed to simulate the reactions and determine the yields to extend the results beyond the experimental observations. -- Highlights: ► 74 PBDEs are identified as the products of debromination via photolysis. ► Debromination is more likely at meta than para positions for PBDEs with ≤8 bromines. ► The stochastic least squares model results agree with and expand the experimental observations. ► Mass imbalance indicates a significant loss of PBDE mass during sunlight exposure. -- The PBDE debromination products and pathways identified in this work will assist in future studies on their environmental fate

  1. Modified optical fiber daylighting system with sunlight transportation in free space.

    Science.gov (United States)

    Vu, Ngoc-Hai; Pham, Thanh-Tuan; Shin, Seoyong

    2016-12-26

    We present the design, optical simulation, and experiment of a modified optical fiber daylighting system (M-OFDS) for indoor lighting. The M-OFDS is comprised of three sub-systems: concentration, collimation, and distribution. The concentration part is formed by coupling a Fresnel lens with a large-core plastic optical fiber. The sunlight collected by the concentration sub-system is propagated in a plastic optical fiber and then collimated by the collimator, which is a combination of a parabolic mirror and a convex lens. The collimated beam of sunlight travels in free space and is guided to the interior by directing flat mirrors, where it is diffused uniformly by a distributor. All parameters of the system are calculated theoretically. Based on the designed system, our simulation results demonstrated a maximum optical efficiency of 71%. The simulation results also showed that sunlight could be delivered to the illumination destination at distance of 30 m. A prototype of the M-OFDS was fabricated, and preliminary experiments were performed outdoors. The simulation results and experimental results confirmed that the M-OFDS was designed effectively. A large-scale system constructed by several M-OFDSs is also proposed. The results showed that the presented optical fiber daylighting system is a strong candidate for an inexpensive and highly efficient application of solar energy in buildings.

  2. Decontamination of poultry feed from ochratoxin A by UV and sunlight radiations.

    Science.gov (United States)

    Ameer Sumbal, Gul; Hussain Shar, Zahid; Hussain Sherazi, Syed Tufail; Sirajuddin; Nizamani, Shafi Muhammad; Mahesar, Safaraz Ahmed

    2016-06-01

    Mycotoxin-contaminated feed is very dangerous for the growth and even life of poultry. The objective of the current study was to investigate the efficacy of ultra-violet irradiation for decontamination of ochratoxin A (OTA) in spiked and naturally contaminated poultry feed samples. Spiked and naturally contaminated feed samples were irradiated with ultra-violet light (UV) at distance of 25 cm over the feed samples. In vitro, the effect of UV intensity (0.1 mW cm(-2) at 254 nm UV-C) on different types of poultry feeds contaminated with OTA was evaluated. The same samples were also irradiated with sunlight and analysed for OTA by an indirect enzyme linked immunosorbent assay method. Poultry feed samples containing 500 µg kg(-1) were 100% decontaminated in 180 min with UV radiation while OTA was decreased to 70-95 µg kg(-1) using the same poultry feed samples after 8 h sunlight irradiation. Therefore, UV light was found to be more effective. Only 1 h of UV irradiation was found to be sufficient to bring the OTA level to the maximum regulatory limit suggested for poultry feeds (100 µg kg(-1) ), while 8 h were needed to obtain this level using sunlight radiations. The proposed approach is a viable option to reduce the level of OTA in contaminated poultry feeds. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

  3. Prevention of hip fractures by exposure to sunlight and pharmacotherapy in patients with Alzheimer's disease.

    Science.gov (United States)

    Iwamoto, Jun; Sato, Yoshihiro; Tanaka, Kiyoshi; Takeda, Tsuyoshi; Matsumoto, Hideo

    2009-01-01

    Hypovitaminosis D and K due to malnutrition or sunlight deprivation, compensatory hyperparathyroidism, increased bone resorption, low bone mineral density (BMD), and an increased risk of falls may contribute to an increased risk of hip fractures in patients with Alzheimer's disease. The purpose of the present study was to clarify the efficacy of interventions against hip fractures in patients with Alzheimer's disease. With respect to randomized controlled trials (RCTs) regarding Alzheimer's disease and hip fractures, the literature was searched with PubMed. Three RCTs were identified, and the relative risk (RR) and 95% confidence interval (CI) were calculated for individual RCTs. Exposure to sunlight with calcium supplementation, menatetrenone (vitamin K2) plus calcium and vitamin D supplementation, and risedronate plus calcium and vitamin D supplementation improved hypovitaminosis D and hyperparathyroidism, contributing to a reduction in bone resorption. Risedronate itself strongly decreased bone resorption. Menatetrenone also decreased the serum level of undercarboxylated osteocalcin. The three interventions increased metacarpal BMD and reduced the incidence of hip fractures. The respective RRs (95% CI) were 0.22 (0.049-0.999), 0.13 (0.031-0.554), and 0.26 (0.100- 0.690). The present study clarified the efficacy of three interventions, including exposure to sunlight, menatetrenone, and risedronate with calcium and/or vitamin D supplementation against hip fractures in patients with Alzheimer's disease.

  4. A new mathematical approximation of sunlight attenuation in rocks for surface luminescence dating

    Energy Technology Data Exchange (ETDEWEB)

    Laskaris, Nikolaos, E-mail: nick.laskaris@gmail.com [University of the Aegean, Department of Mediterranean Studies, Laboratory of Archaeometry, 1 Demokratias Avenue, Rhodes 85100 (Greece); Liritzis, Ioannis, E-mail: liritzis@rhodes.aegean.gr [University of the Aegean, Department of Mediterranean Studies, Laboratory of Archaeometry, 1 Demokratias Avenue, Rhodes 85100 (Greece)

    2011-09-15

    The attenuation of sunlight through different rock surfaces and the thermoluminescence (TL) or Optical stimulated luminescence (OSL) residuals clock resetting derived from sunlight induced eviction of electrons from electron traps, is a prerequisite criterion for potential dating. The modeling of change of residual luminescence as a function of two variables, the solar radiation path length (or depth) and exposure time offers further insight into the dating concept. The double exponential function modeling based on the Lambert-Beer law, valid under certain assumptions, constructed by a quasi-manual equation fails to offer a general and statistically sound expression of the best fit for most rock types. A cumulative log-normal distribution fitting provides a most satisfactory mathematical approximation for marbles, marble schists and granites, where absorption coefficient and residual luminescence parameters are defined per each type of rock or marble quarry. The new model is applied on available data and age determination tests. - Highlights: > Study of aattenuation of sunlight through different rock surfaces. > Study of the thermoluminescence (TL) or Optical stimulated luminescence (OSL) residuals as a function of depth. > A Cumulative Log-Normal Distribution fitting provides the most satisfactory modeling for marbles, marble schists and granites. > The new model (Cummulative Log-Norm Fitting) is applied on available data and age determination tests.

  5. A new mathematical approximation of sunlight attenuation in rocks for surface luminescence dating

    International Nuclear Information System (INIS)

    Laskaris, Nikolaos; Liritzis, Ioannis

    2011-01-01

    The attenuation of sunlight through different rock surfaces and the thermoluminescence (TL) or Optical stimulated luminescence (OSL) residuals clock resetting derived from sunlight induced eviction of electrons from electron traps, is a prerequisite criterion for potential dating. The modeling of change of residual luminescence as a function of two variables, the solar radiation path length (or depth) and exposure time offers further insight into the dating concept. The double exponential function modeling based on the Lambert-Beer law, valid under certain assumptions, constructed by a quasi-manual equation fails to offer a general and statistically sound expression of the best fit for most rock types. A cumulative log-normal distribution fitting provides a most satisfactory mathematical approximation for marbles, marble schists and granites, where absorption coefficient and residual luminescence parameters are defined per each type of rock or marble quarry. The new model is applied on available data and age determination tests. - Highlights: → Study of aattenuation of sunlight through different rock surfaces. → Study of the thermoluminescence (TL) or Optical stimulated luminescence (OSL) residuals as a function of depth. → A Cumulative Log-Normal Distribution fitting provides the most satisfactory modeling for marbles, marble schists and granites. → The new model (Cummulative Log-Norm Fitting) is applied on available data and age determination tests.

  6. Sunlight Effects on Immune System: Is There Something Else in addition to UV-Induced Immunosuppression?

    Directory of Open Access Journals (Sweden)

    D. H. González Maglio

    2016-01-01

    Full Text Available Sunlight, composed of different types of radiation, including ultraviolet wavelengths, is an essential source of light and warmth for life on earth but has strong negative effects on human health, such as promoting the malignant transformation of skin cells and suppressing the ability of the human immune system to efficiently detect and attack malignant cells. UV-induced immunosuppression has been extensively studied since it was first described by Dr. Kripke and Dr. Fisher in the late 1970s. However, skin exposure to sunlight has not only this and other unfavorable effects, for example, mutagenesis and carcinogenesis, but also a positive one: the induction of Vitamin D synthesis, which performs several roles within the immune system in addition to favoring bone homeostasis. The impact of low levels of UV exposure on the immune system has not been fully reported yet, but it bears interesting differences with the suppressive effect of high levels of UV radiation, as shown by some recent studies. The aim of this article is to put some ideas in perspective and pose some questions within the field of photoimmunology based on established and new information, which may lead to new experimental approaches and, eventually, to a better understanding of the effects of sunlight on the human immune system.

  7. Sunlight Effects on Immune System: Is There Something Else in addition to UV-Induced Immunosuppression?

    Science.gov (United States)

    Paz, M. L.; Leoni, J.

    2016-01-01

    Sunlight, composed of different types of radiation, including ultraviolet wavelengths, is an essential source of light and warmth for life on earth but has strong negative effects on human health, such as promoting the malignant transformation of skin cells and suppressing the ability of the human immune system to efficiently detect and attack malignant cells. UV-induced immunosuppression has been extensively studied since it was first described by Dr. Kripke and Dr. Fisher in the late 1970s. However, skin exposure to sunlight has not only this and other unfavorable effects, for example, mutagenesis and carcinogenesis, but also a positive one: the induction of Vitamin D synthesis, which performs several roles within the immune system in addition to favoring bone homeostasis. The impact of low levels of UV exposure on the immune system has not been fully reported yet, but it bears interesting differences with the suppressive effect of high levels of UV radiation, as shown by some recent studies. The aim of this article is to put some ideas in perspective and pose some questions within the field of photoimmunology based on established and new information, which may lead to new experimental approaches and, eventually, to a better understanding of the effects of sunlight on the human immune system. PMID:28070504

  8. Modelling the snowmelt and the snow water equivalent by creating a simplified energy balance conceptual snow model

    Science.gov (United States)

    Riboust, Philippe; Thirel, Guillaume; Le Moine, Nicolas; Ribstein, Pierre

    2016-04-01

    A better knowledge of the accumulated snow on the watersheds will help flood forecasting centres and hydro-power companies to predict the amount of water released during spring snowmelt. Since precipitations gauges are sparse at high elevations and integrative measurements of the snow accumulated on watershed surface are hard to obtain, using snow models is an adequate way to estimate snow water equivalent (SWE) on watersheds. In addition to short term prediction, simulating accurately SWE with snow models should have many advantages. Validating the snow module on both SWE and snowmelt should give a more reliable model for climate change studies or regionalization for ungauged watersheds. The aim of this study is to create a new snow module, which has a structure that allows the use of measured snow data for calibration or assimilation. Energy balance modelling seems to be the logical choice for designing a model in which internal variables, such as SWE, could be compared to observations. Physical models are complex, needing high computational resources and many different types of inputs that are not widely measured at meteorological stations. At the opposite, simple conceptual degree-day models offer to simulate snowmelt using only temperature and precipitation as inputs with fast computing. Its major drawback is to be empirical, i.e. not taking into account all of the processes of the energy balance, which makes this kind of model more difficult to use when willing to compare SWE to observed measurements. In order to reach our objectives, we created a snow model structured by a simplified energy balance where each of the processes is empirically parameterized in order to be calculated using only temperature, precipitation and cloud cover variables. This model's structure is similar to the one created by M.T. Walter (2005), where parameterizations from the literature were used to compute all of the processes of the energy balance. The conductive fluxes into the

  9. Sunlight creates oxygenated species in water-soluble fractions of Deepwater horizon oil

    Energy Technology Data Exchange (ETDEWEB)

    Ray, Phoebe Z. [Department of Chemistry, University of New Orleans, New Orleans, LA 70148 (United States); Chen, Huan [National High Magnetic Field Laboratory, Florida State University, 1800 East Paul Dirac Drive, Tallahassee, FL 32310-4005 (United States); Podgorski, David C. [National High Magnetic Field Laboratory, Florida State University, 1800 East Paul Dirac Drive, Tallahassee, FL 32310-4005 (United States); Future Fuels Institute, Florida State University, 1800 East Paul Dirac Drive, Tallahassee, FL 32310-4005 (United States); McKenna, Amy M. [National High Magnetic Field Laboratory, Florida State University, 1800 East Paul Dirac Drive, Tallahassee, FL 32310-4005 (United States); Tarr, Matthew A., E-mail: mtarr@uno.edu [Department of Chemistry, University of New Orleans, New Orleans, LA 70148 (United States)

    2014-09-15

    Graphical abstract: Sunlight oxygenates petroleum. - Highlights: • Oxidation seen in water-soluble oil fraction after exposure to simulated sunlight. • Oxygen addition occurred across a wide range of carbon number and DBE. • Oil compounds were susceptible to addition of multiple oxygens to each molecule. • Results provide understanding of fate of oil on water after exposure to sunlight. - Abstract: In order to assess the impact of sunlight on oil fate, Macondo well oil from the Deepwater Horizon (DWH) rig was mixed with pure water and irradiated with simulated sunlight. After irradiation, the water-soluble organics (WSO) from the dark and irradiated samples were extracted and characterized by ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Liquid–liquid extraction yielded two fractions from dark and irradiated water/oil mixtures: acidic WSOs (negative-ion electrospray (ESI)), and base/neutral WSOs (positive-ion ESI) coupled to FT-ICR MS to catalog molecular-level transformations that occur to Macondo-derived WSOs after solar irradiation. Such direct measure of oil phototransformation has not been previously reported. The most abundant heteroatom class detected in the irradiated WSO acid fractions correspond to molecules that contain five oxygens (O{sub 5}), while the most abundant acids in the dark samples contain two oxygen atoms per molecule (O{sub 2}). Higher-order oxygen classes (O{sub 5}–O{sub 9}) were abundant in the irradiated samples, but <1.5% relative abundance in the dark sample. The increased abundance of higher-order oxygen classes in the irradiated samples relative to the dark samples indicates that photooxidized components of the Macondo crude oil become water-soluble after irradiation. The base/neutral fraction showed decreased abundance of pyridinic nitrogen (N{sub 1}) concurrent with an increased abundance of N{sub 1}O{sub x} classes after irradiation. The predominance of higher

  10. Assimilation of snow cover and snow depth into a snow model to estimate snow water equivalent and snowmelt runoff in a Himalayan catchment

    NARCIS (Netherlands)

    Stigter, Emmy E.; Wanders, Niko; Saloranta, Tuomo M.; Shea, Joseph M.; Bierkens, M.F.P.; Immerzeel, W.W.

    2017-01-01

    Snow is an important component of water storage in the Himalayas. Previous snowmelt studies in the Himalayas have predominantly relied on remotely sensed snow cover. However, snow cover data provide no direct information on the actual amount of water stored in a snowpack, i.e., the snow water

  11. Sorting Out Seasonal Allergies

    Science.gov (United States)

    ... Close ‹ Back to Healthy Living Sorting Out Seasonal Allergies Sneezing, runny nose, nasal congestion. Symptoms of the ... How do I know if I have seasonal allergies? According to Dr. Georgeson, the best way to ...

  12. Interacting effects of sunlight, agriculturally derived dissolved organic matter and reactive oxygen species on fecal indicator bacteria growth dynamics

    Science.gov (United States)

    Bacterial survival in agriculturally impacted surface waters is dependent on resource availability and also on potential resource transformations, mediated by biotic and abiotic processes. In this study, we focused on the effect of sunlight irradiated cattle fecal extract (CFE) a...

  13. Comparison Study On Sunlight Or Gamma Radiation Aging Resistance Of Poly (Vinyl Pyrrolidone) Aqueous Solution With PVP Nanogel

    International Nuclear Information System (INIS)

    Doan Binh; Pham Thu Hong; Nguyen Nguyet Dieu; Nguyen Thanh Duoc

    2011-01-01

    Comparison study on sunlight or gamma-radiation aging resistance of poly (vinyl pyrrolidone) (PVP) aqueous solution with PVP nanogel at 0.5% was carried out. Sunlight or gamma- radiation aging resistance of PVP aqueous solution and nanogel was evaluated on the basis of their intrinsic viscosity, UV-VIS absorbance, weight averaged molecular weight (M w ). The PVP aqueous solution and nanogel exposed to sunlight in the storage duration of 3 months and to gamma radiation at absorbed doses of 0, 15, 30, 50 kGy were used for this study. Furthermore, the stability of PVP nanogel and of PVP aqueous solution was also studied on the change of their intrinsic viscosity, UV-VIS absorbance, weight averaged molecular weight, particle size distribution and coil size. The experimental results were shown that the aging resistance of PVP nanogel was higher than that of PVP aqueous solution when exposed to gamma radiation or sunlight. (author)

  14. Why We Need More Nature at Work: Effects of Natural Elements and Sunlight on Employee Mental Health and Work Attitudes.

    Science.gov (United States)

    An, Mihyang; Colarelli, Stephen M; O'Brien, Kimberly; Boyajian, Melanie E

    2016-01-01

    This study investigated the effects of natural elements and direct and indirect sunlight exposure on employee mental health and work attitudes. We recruited participants via an online panel from the United States and India, and analyzed data from 444 employees. Natural elements and sunlight exposure related positively to job satisfaction and organizational commitment, and negatively to depressed mood and anxiety. Direct sunlight was a dominant predictor of anxiety; indirect sunlight was a dominant predictor of depressed mood, job satisfaction, and organizational commitment. Natural elements buffered the relationship between role stressors and job satisfaction, depressed mood, and anxiety. We also found that depressed mood partially mediated the relationship between natural elements and job satisfaction. We discuss scientific and policy implications of these findings.

  15. Why We Need More Nature at Work: Effects of Natural Elements and Sunlight on Employee Mental Health and Work Attitudes

    Science.gov (United States)

    An, Mihyang; Colarelli, Stephen M.; O'Brien, Kimberly; Boyajian, Melanie E.

    2016-01-01

    This study investigated the effects of natural elements and direct and indirect sunlight exposure on employee mental health and work attitudes. We recruited participants via an online panel from the United States and India, and analyzed data from 444 employees. Natural elements and sunlight exposure related positively to job satisfaction and organizational commitment, and negatively to depressed mood and anxiety. Direct sunlight was a dominant predictor of anxiety; indirect sunlight was a dominant predictor of depressed mood, job satisfaction, and organizational commitment. Natural elements buffered the relationship between role stressors and job satisfaction, depressed mood, and anxiety. We also found that depressed mood partially mediated the relationship between natural elements and job satisfaction. We discuss scientific and policy implications of these findings. PMID:27214041

  16. Air Ambient-Operated pNIPAM-Based Flexible Actuators Stimulated by Human Body Temperature and Sunlight.

    Science.gov (United States)

    Yamamoto, Yuki; Kanao, Kenichiro; Arie, Takayuki; Akita, Seiji; Takei, Kuniharu

    2015-05-27

    Harnessing a natural power source such as the human body temperature or sunlight should realize ultimate low-power devices. In particular, macroscale and flexible actuators that do not require an artificial power source have tremendous potential. Here we propose and demonstrate electrically powerless polymer-based actuators operated at ambient conditions using a packaging technique in which the stimulating power source is produced by heat from the human body or sunlight. The actuating angle, force, and reliability are discussed as functions of temperature and exposure to sunlight. Furthermore, a wearable device platform and a smart curtain actuated by the temperature of human skin and sunlight, respectively, are demonstrated as the first proof-of-concepts. These nature-powered actuators should realize a new class of ultimate low-power devices.

  17. Sunlight exposure behaviour and vitamin D status in photosensitive patients: longitudinal comparative study with healthy individuals at U.K. latitude.

    Science.gov (United States)

    Rhodes, L E; Webb, A R; Berry, J L; Felton, S J; Marjanovic, E J; Wilkinson, J D; Vail, A; Kift, R

    2014-12-01

    Low vitamin D status is prevalent in wintertime in populations at northerly latitudes. Photosensitive patients are advised to practise sun avoidance, but their sunlight exposure levels, photoprotective measures and resulting vitamin D status are unknown. To examine seasonal vitamin D status in photosensitive patients relative to healthy individuals and to assess quantitatively behavioural and demographic contributors. This was a longitudinal prospective cohort study (53·5°N) examining year-round 25-hydroxyvitamin D [25(OH)D] levels, sun-exposure behaviour and oral vitamin D intake in photosensitive patients diagnosed at a photoinvestigation unit (n = 53), compared with concurrently assessed healthy adults (n = 109). Photosensitive patients achieved seasonal 25(OH)D variation, but insufficient (vitamin D intake was low in both groups (photosensitive: 2·94 μg per day). Supplementation and summer surface area exposure predicted summer peak and winter trough 25(OH)D levels. A 1 μg per day increment in supplementary vitamin D raised summer and winter 25(OH)D by 5% (95% CI 3-7) and 9% (95% CI 5-12), respectively (both P vitamin D status. Guidance on oral measures should target this patient group and their physicians. © 2014 British Association of Dermatologists.

  18. Seasonal Allergies (Hay Fever)

    Science.gov (United States)

    ... Safe Videos for Educators Search English Español Seasonal Allergies (Hay Fever) KidsHealth / For Parents / Seasonal Allergies (Hay ... español Alergia estacional (fiebre del heno) About Seasonal Allergies "Achoo!" It's your son's third sneezing fit of ...

  19. Seasonal Variation in Epidemiology

    Science.gov (United States)

    Marrero, Osvaldo

    2013-01-01

    Seasonality analyses are important in medical research. If the incidence of a disease shows a seasonal pattern, then an environmental factor must be considered in its etiology. We discuss a method for the simultaneous analysis of seasonal variation in multiple groups. The nuts and bolts are explained using simple trigonometry, an elementary…

  20. A sunlight-induced method for rapid biosynthesis of silver nanoparticles using an Andrachnea chordifolia ethanol extract

    Energy Technology Data Exchange (ETDEWEB)

    Karimi Zarchi, A.A.; Faridi Majidi, R. [Tehran University of Medical Sciences, Department of Nanomedicine, School of Advanced Medical Technologies, Tehran (Iran, Islamic Republic of); Mokhtari, N.; Shahverdi, A.R. [Tehran University of Medical Sciences, Department of Pharmaceutical Biotechnology and Medicinal Plants Research Center, Faculty of Pharmacy, Tehran (Iran, Islamic Republic of); Arfan, M.; Rehman, T.; Ali, M. [University of Peshawar, Institute of Chemical Sciences, Peshawar, Khyber Pakhtoonkhwa (Pakistan); Amini, M. [Tehran University of Medical Sciences, Department of Medicinal Chemistry, Faculty of Pharmacy, Tehran (Iran, Islamic Republic of)

    2011-05-15

    In this study a sunlight-induced method for rapid synthesis of silver nanoparticles using an ethanol extract of Andrachnea chordifolia is described. The silver nitrate solutions (1 mM) containing the ethanol extract of Andrachnea chordifolia were irradiated by both sunlight radiation and by sunlight radiation passed through different colored filters (red, yellow or green). The smallest size of silver nanoparticles was obtained when a silver ion solution was irradiated for 5 minutes by direct sunlight radiation. Further examination of the shape and size and of the surface chemistry of these biogenic silver nanoparticles, which were prepared under sunlight radiation, was carried out using transmission electron microscopy and infrared spectroscopy, respectively. Transmission electron microscopy images show spherical particles with an average size of 3.4 nm. Hydroxyl residues were also detected on the surface of these biogenic silver nanoparticles fabricated using plant extract of Andrachnea chordifolia under sunlight radiation. Our study on the reduction of silver ions by this plant extract in darkness shows that the synthesis process can take place under dark conditions at much longer incubations (48 hours). Larger silver polydispersed nanoparticles ranging in size from 3 to 30 nm were obtained when the silver ions were treated with the ethanol extract of Andrachnea chordifolia under dark conditions for 48 hours. (orig.)

  1. Sunlight persistence and rainfastness of spray-dried formulations of baculovirus isolated from Anagrapha falcifera (Lepidoptera: Noctuidae).

    Science.gov (United States)

    Tamez-Guerra, P; McGuire, M R; Behle, R W; Hamm, J J; Sumner, H R; Shasha, B S

    2000-04-01

    Nuclear polyhedrosis viruses such as the one isolated from the celery looper, Anagrapha falcifera (Kirby) (AfMNPV), have the potential to be successful bioinsecticides if improved formulations can prevent rapid loss of insecticidal activity from environmental conditions such as sunlight and rainfall. We tested 16 spray-dried formulations of AfMNPV to determine the effect of different ingredients (e.g., lignin, corn flour, and so on) on insecticidal activity after simulated rain and simulated sunlight (at Peoria, IL) and natural sunlight exposures (at Tifton, GA). The most effective formulation contained pregelatinized corn flour and potassium lignate, which retained more than half of its original activity after 5 cm of simulated rain, and almost full activity after 8 h of simulated sunlight. In Georgia, formulations made with and without lignin were compared for persistence of insecticidal activity when exposed to natural sunlight. In addition, the effect of fluorescent brighteners as formulation components and spray tank additives was tested. Results showed that the formulations with lignin had more insecticidal activity remaining after sunlight exposure than formulations without lignin. The inclusion of brighteners in the formulation did not improve initial activity or virus persistence. However, a 1% tank mix significantly enhanced activity and improved persistence. Scanning electron micrographs revealed discreet particles, and transmission electron micrographs showed virus embedded within microgranules. Results demonstrated that formulations made with natural ingredients could improve persistence of virus-based biopesticides.

  2. Cultural variation in seasonal depression: cross-national differences in winter versus summer patterns of seasonal affective disorder.

    Science.gov (United States)

    Kasof, Joseph

    2009-05-01

    Research suggests that two dimensions of national culture, individualism-collectivism and power distance, predict affective responses to the seasonally varying levels of ambient sunlight that may underlie regular cycles of mood and behavior in Seasonal Affective Disorder (SAD). Specifically, negative affect is predicted by the diminished sunlight of fall-winter in countries higher in individualism and lower in power distance, and by the increased sunlight of spring-summer in countries lower in individualism and higher in power distance. This study tests whether individualism correlates positively, and power distance negatively, with the frequency of winter-SAD relative to that of summer-SAD. A search for studies reporting frequencies of both winter-SAD and summer-SAD identified 55 samples encompassing 18 countries and 38,408 participants, including 1931 with SAD. The frequency of winter-SAD, relative to that of summer-SAD, correlated positively with individualism (r=.67, p=.001) and negatively with power distance (r=-.72, p=.0001). Countries in which winter-SAD was more common than summer-SAD were significantly more individualistic and less power-distant than countries in which summer-SAD was more common than winter-SAD. Results survived various tests of threats to validity. The study is limited by the quantity, quality, diversity, and representativeness of the research under review and by its correlational design. Individualism and power distance are strongly related to the relative prevalence of winter-SAD and summer-SAD. Culture may play an important but previously overlooked role in the etiology of SAD.

  3. Dynamic light absorption of biomass-burning organic carbon photochemically aged under natural sunlight

    Science.gov (United States)

    Zhong, M.; Jang, M.

    2014-02-01

    Wood-burning aerosol produced under smoldering conditions was photochemically aged with different relative humidity (RH) and NOx conditions using a 104 m3 dual outdoor chamber under natural sunlight. Light absorption of organic carbon (OC) was measured over the course of photooxidation using a UV-visible spectrometer connected to an integrating sphere. At high RH, the color decayed rapidly. NOx slightly prolonged the color of wood smoke, suggesting that NOx promotes the formation of chromophores via secondary processes. Overall, the mass absorption cross section (integrated between 280 and 600 nm) of OC increased by 11-54% (except high RH) in the morning and then gradually decreased by 19-68% in the afternoon. This dynamic change in light absorption of wood-burning OC can be explained by two mechanisms: chromophore formation and sunlight bleaching. To investigate the effect of chemical transformation on light absorption, wood smoke particles were characterized using various spectrometers. The intensity of fluorescence, which is mainly related to polycyclic aromatic hydrocarbons (PAHs), rapidly decreased with time, indicating the potential bleaching of PAHs. A decline of levoglucosan concentrations evinced the change of primary organic aerosol with time. The aerosol water content measured by Fourier transform infrared spectroscopy showed that wood-burning aerosol became less hygroscopic as photooxidation proceeded. A similar trend in light absorption changes has been observed in ambient smoke aerosol originating from the 2012 County Line wildfire in Florida. We conclude that the biomass-burning OC becomes less light absorbing after 8-9 h sunlight exposure compared to fresh wood-burning OC.

  4. Dynamic light absorption of biomass burning organic carbon photochemically aged under natural sunlight

    Science.gov (United States)

    Zhong, M.; Jang, M.

    2013-08-01

    Wood burning aerosol produced under smoldering conditions was photochemically aged with different relative humidity (RH) and NOx conditions using a 104 m3 dual outdoor chamber under natural sunlight. Light absorption of organic carbon (OC) was measured over the course of photooxidation using a UV-visible spectrometer connected to an integrating sphere. At high RH, the color decayed rapidly. NOx slightly prolonged the color of wood smoke, suggesting that NOx promotes the formation of chromophores via secondary processes. Overall, the mass absorption cross-section (integrated between 280 nm and 600 nm) of OC increased by 11-54% (except high RH) in the morning and then gradually decreased by 19-68% in the afternoon. This dynamic change in light absorption of wood burning OC can be explained by two mechanisms: chromophore formation and sunlight bleaching. To investigate the effect of chemical transformation on light absorption, wood smoke particles were characterized using various spectrometers. The intensity of fluorescence, which is mainly related to polycyclic aromatic hydrocarbons (PAHs), rapidly decreased with time indicating the potential bleaching of PAHs. A decline of levoglucosan concentrations evinced the change of POA with time. The aerosol water content measured by Fourier transform infrared spectroscopy showed that wood burning aerosol became less hygroscopic as photooxidation proceeded. A similar trend in light absorption changes has been observed in ambient smoke aerosol originating from the 2012 County Line Wildfire in Florida. We conclude that the biomass burning OC becomes less light absorbing after 8-9 h sunlight exposure compared to fresh wood burning OC.

  5. Formation of rutile fasciculate zone induced by sunlight irradiation at room temperature and its hemocompatibility

    International Nuclear Information System (INIS)

    Zhang, Xuan-Hui; Zheng, Xiang; Cheng, Yuan; Li, Guo-Hua; Chen, Xiao-Ping; Zheng, Jian-Hui

    2013-01-01

    The fasciculate zone of phase pure rutile was fabricated under sunlight irradiation at room temperature, using titanium tetrachloride as a sole precursor. The crystal phase, morphology and microstructure, and optical absorption behavior of the samples were characterized by X-ray Diffraction, High-Resolution Transmission Electron Microscope (HRTEM) and UV–vis Diffuse Reflectance Spectra (DRS), respectively. XRD results show that the crystal phase of the sample is composed of rutile only, and a lattice distortion displays in the crystallite of the sample. HRTEM results show that the morphology of rutile particle is fasciculate zone constituted of nanoparticles with a diameter of 4–7 nm, and these particles grow one by one and step by step. The pattern of the selected area electron diffraction of the sample is Kikuchi type, which can be attributed to the predominant orientation growth of rutile nanoparticles along [001] induced by sunlight irradiation. DRS results show that the absorption threshold of the sample is 415 nm, corresponding to the band gap energy of 2.99 eV, which is lower than the band gap energy of rutile, 3.03 eV. Blood compatibility measurement shows that the sample has no remarkable effect on hemolytic and coagulation activity. The percent hemolysis of red blood cells is less than 5% even treated with a big dosage of the fasciculate rutile and under UV irradiation, and there are no obvious changes of plasma recalcification time after the rutile treatment. Thus, the novel structure of rutile fasciculate has low potential toxicity for blood and is hemocompatibility safe. Highlights: • A novel approach to fabricate the fasciculate zone of phase pure rutile • The fasciculate grows from a particle to nanorod and to fasciculate, step by step. • A preferred orientation growth induced by sunlight irradiation in the fasciculate • The rutile fasciculate is low toxicity for blood and is hemocompatibility safe

  6. Greenhouse effect: temperature of a metal sphere surrounded by a glass shell and heated by sunlight

    International Nuclear Information System (INIS)

    Nguyen, Phuc H; Matzner, Richard A

    2012-01-01

    We study the greenhouse effect on a model satellite consisting of a tungsten sphere surrounded by a thin spherical, concentric glass shell, with a small gap between the sphere and the shell. The system sits in vacuum and is heated by sunlight incident along the z-axis. This development is a generalization of the simple treatment of the greenhouse effect given by Kittel and Kroemer (1980 Thermal Physics (San Francisco: Freeman)) and can serve as a very simple model demonstrating the much more complex Earth greenhouse effect. Solution of the model problem provides an excellent pedagogical tool at the Junior/Senior undergraduate level.

  7. Sunlight simulators-the key to understanding the physiological effects of the sun

    CSIR Research Space (South Africa)

    Singh, A

    2006-07-01

    Full Text Available simulator Slide 4 © CSIR 2006 www.csir.co.za ۞ Benefits of natural sunlight ۞ Restrictions of lifestyles ۞ Common misconceptions ۞ Experimental setups Slide 5 © CSIR 2006 www.csir.co.za Cancer Males...,043 181,439 Lung 965,241 848,132 386,891 330,786 Melanoma of skin 79,043 21,952 81,134 18,829 Breast 1,151,298 410,712 Leukemia 171,037 125,142 129,485 97,364 All sites but skin 5,801,839 3,795,991 5,060,657 2...

  8. Bacterial growth in humic waters exposed to UV-radiation and simulated sunlight

    DEFF Research Database (Denmark)

    Corin, N.; Backlund, P.; Wiklund, T.

    1998-01-01

    Sterile filtered (0.45 mu m) humic lake water was exposed to simulated sunlight (300-800 nm) or W-radiation (254 run)for various periods of times and the dissolved organic carbon content, absorbance at 254 and 460 nm and PH were recorded. The irradiated water was inoculated with a natural bacterial...... assemblage and the number of viable bacteria war estimated 3 and 5 days after the inoculation using the plate count technique. The number of viable bacteria increased with the irradiation time indicating that the chemical changes of the humus macromolecules observed during irradiation resulted...

  9. Concentration of sunlight to solar-surface levels using non-imaging optics

    Science.gov (United States)

    Gleckman, Philip; O'Gallagher, Joseph; Winston, Roland

    1989-05-01

    An account is given of the design and operational principles of a solar concentrator that employs nonimaging optics to achieve a solar flux equal to 56,000 times that of ambient sunlight, yielding temperatures comparable to, and with further development of the device, exceeding those of the solar surface. In this scheme, a parabolic mirror primary concentrator is followed by a secondary concentrator, designed according to the edge-ray method, which is filled with a transparent oil. The device may be used in materials-processing, waste-disposal, and solar-pumped laser applications.

  10. Use of sunlight to degrade oxytetracycline in marine aquaculture's waters

    International Nuclear Information System (INIS)

    Leal, J.F.; Esteves, V.I.; Santos, E.B.H.

    2016-01-01

    Oxytracycline (OTC) is a broad spectrum antibiotic authorized for use in European aquaculture. Its photo-degradation has been widely studied in synthetic aqueous solutions, sometimes resorting to expensive methods and without proven effectiveness in natural waters. Thus, this work studied the possibility to apply the solar photo-degradation for removal of OTC from marine aquaculture's waters. For that, water samples were collected at different locals of the water treatment circuit, from two different aquaculture companies. Water samples were firstly characterized regarding to pH, salinity, total suspended solids (TSS), organic carbon and UV–Vis spectroscopic characteristics. Then, the samples were spiked with OTC and irradiated using simulated sunlight in order to evaluate the matrix effects on OTC photo-degradation. From kinetic results, the apparent quantum yields and the outdoor half-life times, at 40°N for midsummer and midwinter days were estimated by the first time for these conditions. For a midsummer day, at sea level, the outdoor half-life time predicted for OTC in these aquaculture's waters ranged between 21 and 25 min. Additionally, the pH and salinity effects on the OTC photo-degradation were evaluated and it has been shown that high pH values and the presence of sea salt increase the OTC photo-degradation rate in aquaculture's waters, compared to results in deionised water. The results are very promising to apply this low-cost methodology using the natural sunlight in aquaculture's waters to remove OTC. - Highlights: • Oxytetracycline (OTC) is one of the most used antibiotics in aquaculture. • OTC photolysis in marine aquaculture's water is faster than in deionised water. • The sunlight radiation quickly remove the OTC from aquaculture's water. • Outdoor half-life for a midsummer day is 21–25 min in aquaculture's water. • High pH's and salinities increase the OTC photo-degradation. - This work

  11. Session 6: photo-catalytic degradation of Toluene using sunlight-type excitation

    Energy Technology Data Exchange (ETDEWEB)

    Fuerte, A.; Hernandez-Alonso, M.D.; Martinez-Arias, A.; Conesa, J.C.; Soria, J.; Fernandez-Garcia, M. [Instituto de Catalisis y Petroleoquimica, CSIC, -Madrid (Spain)

    2004-07-01

    In this report we investigate the doping of anatase-TiO{sub 2} with nine different cations. It is shown that W can be one of the best options for toluene photo-degradation using sunlight-type excitation. Thermal and hydrothermal treatments were applied to amorphous Ti-W mixed oxide precursors with varying W:Ti atomic ratio for obtaining nano-structured particles having different properties. All Ti-W precursors were prepared by a microemulsion method and the mixed oxides characterized by using XRD, XPS, as well as XAFS, Raman and UV-Vis Spectroscopies. (authors)

  12. Sunlight-Induced Photochemical Degradation of Methylene Blue by Water-Soluble Carbon Nanorods

    Directory of Open Access Journals (Sweden)

    Anshu Bhati

    2016-01-01

    Full Text Available Water-soluble graphitic hollow carbon nanorods (wsCNRs are exploited for their light-driven photochemical activities under outdoor sunlight. wsCNRs were synthesized by a simple pyrolysis method from castor seed oil, without using any metal catalyst or template. wsCNRs exhibited the light-induced photochemical degradation of methylene blue used as a model pollutant by the generation of singlet oxygen species. Herein, we described a possible degradation mechanism of methylene blue under the irradiation of visible photons via the singlet oxygen-superoxide anion pathway.

  13. Persistence of marine fish environmental DNA and the influence of sunlight.

    Directory of Open Access Journals (Sweden)

    Elizabeth A Andruszkiewicz

    Full Text Available Harnessing information encoded in environmental DNA (eDNA in marine waters has the potential to revolutionize marine biomonitoring. Whether using organism-specific quantitative PCR assays or metabarcoding in conjunction with amplicon sequencing, scientists have illustrated that realistic organism censuses can be inferred from eDNA. The next step is establishing ways to link information obtained from eDNA analyses to actual organism abundance. This is only possible by understanding the processes that control eDNA concentrations. The present study uses mesocosm experiments to study the persistence of eDNA in marine waters and explore the role of sunlight in modulating eDNA persistence. We seeded solute-permeable dialysis bags with water containing indigenous eDNA and suspended them in a large tank containing seawater. Bags were subjected to two treatments: half the bags were suspended near the water surface where they received high doses of sunlight, and half at depth where they received lower doses of sunlight. Bags were destructively sampled over the course of 87 hours. eDNA was extracted from water samples and used as template for a Scomber japonicus qPCR assay and a marine fish-specific 12S rRNA PCR assay. The latter was subsequently sequenced using a metabarcoding approach. S. japonicus eDNA, as measured by qPCR, exhibited first order decay with a rate constant ~0.01 hr -1 with no difference in decay rate constants between the two experimental treatments. eDNA metabarcoding identified 190 organizational taxonomic units (OTUs assigned to varying taxonomic ranks. There was no difference in marine fish communities as measured by eDNA metabarcoding between the two experimental treatments, but there was an effect of time. Given the differences in UVA and UVB fluence received by the two experimental treatments, we conclude that sunlight is not the main driver of fish eDNA decay in the experiments. However, there are clearly temporal effects that

  14. Dispersed single-phase-step Michelson interferometer for Doppler imaging using sunlight.

    Science.gov (United States)

    Wan, Xiaoke; Ge, Jian

    2012-09-15

    A Michelson interferometer is dispersed with a fiber array-fed spectrograph, providing 59 Doppler sensing channels using sunlight in the 510-570 nm wavelength region. The interferometer operates at a single-phase-step mode, which is particularly advantageous in multiplexing and data processing compared to the phase-stepping mode of other interferometer spectrometer instruments. Spectral templates are prepared using a standard solar spectrum and simulated interferometer modulations, such that the correlation function with a measured 1D spectrum determines the Doppler shift. Doppler imaging of a rotating cylinder is demonstrated. The average Doppler sensitivity is ~12 m/s, with some channels reaching ~5 m/s.

  15. Temporal Stability of the Microbial Community in Sewage-Polluted Seawater Exposed to Natural Sunlight Cycles and Marine Microbiota

    Science.gov (United States)

    Sassoubre, Lauren M.; Yamahara, Kevan M.

    2015-01-01

    Billions of gallons of untreated wastewater enter the coastal ocean each year. Once sewage microorganisms are in the marine environment, they are exposed to environmental stressors, such as sunlight and predation. Previous research has investigated the fate of individual sewage microorganisms in seawater but not the entire sewage microbial community. The present study used next-generation sequencing (NGS) to examine how the microbial community in sewage-impacted seawater changes over 48 h when exposed to natural sunlight cycles and marine microbiota. We compared the results from microcosms composed of unfiltered seawater (containing naturally occurring marine microbiota) and filtered seawater (containing no marine microbiota) to investigate the effect of marine microbiota. We also compared the results from microcosms that were exposed to natural sunlight cycles with those from microcosms kept in the dark to investigate the effect of sunlight. The microbial community composition and the relative abundance of operational taxonomic units (OTUs) changed over 48 h in all microcosms. Exposure to sunlight had a significant effect on both community composition and OTU abundance. The effect of marine microbiota, however, was minimal. The proportion of sewage-derived microorganisms present in the microcosms decreased rapidly within 48 h, and the decrease was the most pronounced in the presence of both sunlight and marine microbiota, where the proportion decreased from 85% to 3% of the total microbial community. The results from this study demonstrate the strong effect that sunlight has on microbial community composition, as measured by NGS, and the importance of considering temporal effects in future applications of NGS to identify microbial pollution sources. PMID:25576619

  16. Increased polycyclic aromatic hydrocarbon toxicity following their photomodification in natural sunlight: impacts on the duckweed Lemna gibba L. G-3

    International Nuclear Information System (INIS)

    Huang, X.D.; Dixon, D.G.; Greenberg, B.M.

    1995-01-01

    The authors previously demonstrated that simulated solar radiation (SSR), with a fluence rate of only 40 mumol m -2 sec -1 , increased polycyclic aromatic hydrocarbon (PAH) toxicity to the duckweed Lemna gibba and that PAHs photomodified in SSR (generally oxygenation of the ring system) are more toxic than the parent compounds (Huang et al., Environ. Toxicol. Chem., 1993, 12, 1067-1077). It is not known, however, to what extent toxicity of PAHs can increase due to photomodification. Thus, natural sunlight, which has a high fluence rate (approximately 2000 mumol m -2 sec -1 ), was used to photomodify anthracene, benzo[a]pyrene, fluoranthene, phenanthrene, and pyrene. Toxicity was based on growth inhibition of L. gibba, measured as the rate of production of new leaves over an 8-day period. Initially, the toxicity of the PAHs applied in intact form was probed, with the compounds demonstrating greater toxicity in sunlight than in SSR. Next the PAHs were photomodified in sunlight prior to incubation with the plants. The half-lives of the PAHs in sunlight ranged from 12 min to 30 hr. Although most of the products of PAH photomodification are not yet identified, the degree that PAH toxicity increased following photomodification in sunlight could still be probed. The mixtures of photomodified chemicals that were derived from each PAH in sunlight were applied of L. gibba and growth inhibition under 100 mumol m -2 sec -1 of SSR was determined. The LC50s for the PAH photoproducts generated in sunlight were an order of magnitude lower than the LC50s for the PAHs applied in intact form. (author)

  17. Modeling Aspect Controlled Formation of Seasonally Frozen Ground on Montane Hillslopes: a Case Study from Gordon Gulch, Colorado

    Science.gov (United States)

    Rush, M.; Rajaram, H.; Anderson, R. S.; Anderson, S. P.

    2017-12-01

    The Intergovernmental Panel on Climate Change (2013) warns that high-elevation ecosystems are extremely vulnerable to climate change due to short growing seasons, thin soils, sparse vegetation, melting glaciers, and thawing permafrost. Many permafrost-free regions experience seasonally frozen ground. The spatial distribution of frozen soil exerts a strong control on subsurface flow and transport processes by reducing soil permeability and impeding infiltration. Accordingly, evolution of the extent and duration of frozen ground may alter streamflow seasonality, groundwater flow paths, and subsurface storage, presenting a need for coupled thermal-hydrologic models to project hydrologic responses to climate warming in high-elevation regions. To be useful as predictive tools, such models should incorporate the heterogeneity of solar insolation, vegetation, and snowpack dynamics. We present a coupled thermal-hydrologic modeling study against the backdrop of field observations from Gordon Gulch, a seasonally snow-covered montane catchment in the Colorado Front Range in the Boulder Creek Critical Zone Observatory. The field site features two instrumented hillslopes with opposing aspects: the snowpack on the north-facing slope persists throughout much of the winter season, while the snowpack on the south-facing slope is highly ephemeral. We implemented a surface energy balance and snowpack accumulation and ablation model that is coupled to the subsurface flow and transport code PFLOTRAN-ICE to predict the hydrologic consequences of aspect-controlled frozen soil formation during water years 2013-2016. Preliminary model results demonstrate the occurrence of seasonally-frozen ground on the north-facing slope that directs snowmelt to the stream by way of shallow subsurface flow paths. The absence of persistently frozen ground on the south-facing slope allows deeper infiltration of snowmelt recharge. The differences in subsurface flow paths also suggest strong aspect

  18. Photoelectrochemical-type sunlight photodetector based on MoS2/graphene heterostructure

    International Nuclear Information System (INIS)

    Huang, Zongyu; Han, Weijia; Chander, D Sathish; Qi, Xiang; Zhang, Han; Tang, Hongli; Ren, Long

    2015-01-01

    We have fabricated a novel sunlight photo-detector based on a MoS 2 /graphene heterostructure. The MoS 2 /graphene heterostructure was prepared by a facile hydrothermal method along with a subsequent annealing process followed by a substrate-induced high selective nucleation and growth mechanism. The microstructures and morphologies of the two-dimensional MoS 2 /graphene heterostructure can be experimentally confirmed by x-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and a UV–vis absorption spectrometer. Photoresponse investigations performed by a photoelectrochemical (PEC) measurement system indicate that the synthesized MoS 2 /graphene heterostructure shows superior photoresponse activities under the illumination of sunlight in contrast with bare MoS 2 and graphene. The improved photoresponsivity can be attributed to the enhanced light absorption, strong light–matter interaction and the extremely efficient charge separation of the heterostructure. The structure and performances of the MoS 2 /graphene heterostructure suggest promising applications in the field of photonics and optoelectronics. (paper)

  19. Dissolved organic carbon biodegradability from thawing permafrost stimulated by sunlight rather than inorganic nitrogen

    Science.gov (United States)

    Liu, F.; Chen, L.; Zhang, B.; Wang, G.; Qin, S.; Yang, Y.

    2017-12-01

    Permafrost thaw could result in a large portion of frozen carbon being laterally transferred to aquatic ecosystems as dissolved organic carbon (DOC). During this delivery process, the size of biodegradable DOC (BDOC) determines the proportion of DOC mineralized by microorganisms and associated carbon loss to the atmosphere, which may further trigger positive carbon-climate feedback. Thermokarst is an abrupt permafrost thaw process that can enhance DOC export and also impact DOC processing through increased inorganic nitrogen (N) and sunlight exposure. However, it remains unclear how thermokarst-impacted BDOC responds to inorganic N addition and ultraviolet (UV) light irradiation. Here we explored the responses of DOC concentration, composition and its biodegradability to inorganic N and UV light in a typical thermokarst on the Tibetan Plateau, by combining field observation and laboratory incubation with spectra analyses (UV-visible absorption and three-dimensional fluorescence spectra) and parallel factor analyses. Our results showed that BDOC in thermokarst feature outflows was significantly higher than in reference water. Furthermore, inorganic N addition had no influence on thermokarst-impacted BDOC, whereas exposure to UV light significantly increased BDOC by as much as 2.3 times higher than the dark-control. Moreover, N addition and UV irradiation did not generate additive effects on BDOC. These results imply that sunlight rather than inorganic N can increase thermokarst-derived BDOC, potentially strengthening the positive permafrost carbon-climate feedback.

  20. Terrestrial photovoltaic power systems with sunlight concentration. Annual progress report, January 1, 1975--December 31, 1975

    Energy Technology Data Exchange (ETDEWEB)

    Backus, C.E.

    1976-01-31

    This annual report is for the second year of a program to investigate the characteristics of the components and the total system using sunlight concentrated onto solar cells. The second year was primarily to experimentally investigate the conclusions of the first year of analytical studies. Cells have been fabricated that are designed for different intensities. Typically the efficiency of a cell will increase from its 11 percent at AM1 peak to efficiency at the designed concentration level and return to its initial efficiency at about 3 times its designed concentration level. The developed cells have been tested under high intensity simulators and in concentrated sunlight and have shown to have the predicted response. The experimental testing of passive cooling limitations for cooling cells with just finned arrangements in the back of the cell has been completed in the controlled environment of a wind tunnel. These experiments have confirmed the heat transfer coefficients that had been used in the analytical studies. Testing was done to collect heat transfer coefficients for actual wind conditions and these data show good agreement with the controlled wind tunnel data. Four photovoltaic/concentrator system experiments have been started with CR of about 3, 10, 25, and 100. System analysis has indicated that photovoltaic concentration systems may be attractive in low solar irradiation areas such as Cleveland.

  1. A full-sunlight-driven photocatalyst with super long-persistent energy storage ability.

    Science.gov (United States)

    Li, Jie; Liu, Yuan; Zhu, Zhijian; Zhang, Guozhu; Zou, Tao; Zou, Zhijun; Zhang, Shunping; Zeng, Dawen; Xie, Changsheng

    2013-01-01

    A major drawback of traditional photocatalysts like TiO2 is that they can only work under illumination, and the light has to be UV. As a solution for this limitation, visible-light-driven energy storage photocatalysts have been developed in recent years. However, energy storage photocatalysts that are full-sunlight-driven (UV-visible-NIR) and possess long-lasting energy storage ability are lacking. Here we report, a Pt-loaded and hydrogen-treated WO3 that exhibits a strong absorption at full-sunlight spectrum (300-1,000 nm), and with a super-long energy storage time of more than 300 h to have formaldehyde degraded in dark. In this new material system, the hydrogen treated WO3 functions as the light harvesting material and energy storage material simultaneously, while Pt mainly acts as the cocatalyst to have the energy storage effect displayed. The extraordinary full-spectrum absorption effect and long persistent energy storage ability make the material a potential solar-energy storage and an effective photocatalyst in practice.

  2. A pathway for sustainable conversion of sunlight to hydrogen using proposed compact CPV system

    KAUST Repository

    Burhan, Muhammad

    2018-03-22

    Solar energy being intermittent in nature, can provide a sustainable, steady and high density energy source when converted into electrolytic hydrogen. However, in current photovoltaic market trend with 99% conventional single junction PV panels, this cannot be achieved efficiently and economically. The advent of the multi-junction solar cells (MJCs), with cell-efficiency exceeding 46%, has yet to receive wide spread acceptance in the current PV market in form of concentrated photovoltaic (CPV) system, because of its system design complexity, limiting its application scope and customers. The objective of this paper is to develop a low cost compact CPV system that will not only eliminate its application and installation related restrictions but it is also introducing a highly efficient and sustainable photovoltaic system for common consumer, to convert intermittent sunlight into green hydrogen. The developed CPV system negates the common conviction by showing two times more power output than the flat plate PV, in tropical region. In addition, sunlight to hydrogen conversion efficiency of 18% is recorded for CPV, which is two times higher than alone electricity production efficiency of flat plate PV.

  3. Roles of Saccharomyces cerevisiae DNA polymerases Poleta and Polzeta in response to irradiation by simulated sunlight.

    Science.gov (United States)

    Kozmin, Stanislav G; Pavlov, Youri I; Kunkel, Thomas A; Sage, Evelyne

    2003-08-01

    Sunlight causes lesions in DNA that if unrepaired and inaccurately replicated by DNA polymerases yield mutations that result in skin cancer in humans. Two enzymes involved in translesion synthesis (TLS) of UV-induced photolesions are DNA polymerase eta (Poleta) and polymerase zeta (Polzeta), encoded by the RAD30A and REV3 genes, respectively. Previous studies have investigated the TLS roles of these polymerases in human and yeast cells irradiated with monochromatic, short wavelength UVC radiation (254 nm). However, less is known about cellular responses to solar radiation, which is of higher and mixed wavelengths (310-1100 nm) and produces a different spectrum of DNA lesions, including Dewar photoproducts and oxidative lesions. Here we report on the comparative cytotoxic and mutagenic effects of simulated sunlight (SSL) and UVC radiation on yeast wild-type, rad30Delta, rev3Delta and rev3Delta rad30Delta strains. The results with SSL support several previous interpretations on the roles of these two polymerases in TLS of photodimers and (6-4) photoproducts derived from studies with UVC. They further suggest that Poleta participates in the non-mutagenic bypass of SSL-dependent cytosine-containing Dewar photoproducts and 8-oxoguanine, while Polzeta is mainly responsible for the mutagenic bypass of all types of Dewar photoproducts. They also suggest that in the absence of Polzeta, Poleta contributes to UVC- and SSL-induced mutagenesis, possibly by the bypass of photodimers containing deaminated cytosine.

  4. Factors influencing adherence with therapeutic sunlight exposure in older people in intermediate care facilities.

    Science.gov (United States)

    Durvasula, Seeta; Sambrook, Philip N; Cameron, Ian D

    2012-01-01

    The purpose of this study was to investigate the factors influencing low adherence with therapeutic sunlight exposure in a randomized controlled trial conducted with older people living in intermediate care facilities. The study involved participants in the FREEDOM (Falls Risk Epidemiology: Effect of vitamin D on skeletal Outcomes and other Measures) study, a randomized controlled trial of therapeutic sun exposure to reduce falls in older people in intermediate care facilities. Semi-structured interviews were conducted with thirty participants in the FREEDOM trial, and with ten sunlight officers who were employed to facilitate the sun exposure. Two focus groups involving 10 participants in the FREEDOM trial were also held at the end of the intervention period. Common themes were derived from the interview and focus group transcripts. The study showed that the perceived health benefits did not influence adherence with the sun exposure. Factors such as socializing with others and being outdoors were more important in encouraging attendance. The main barriers to adherence included the perceived inflexibility and regimentation of daily attendance, clash with other activities, unsuitable timing and heat discomfort. This study showed that providing greater flexibility and autonomy to older people in how and when they receive sun exposure is likely to improve adherence. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  5. Natural organic matter and sunlight accelerate the degradation of 17ss-estradiol in water

    International Nuclear Information System (INIS)

    Leech, Dina M.; Snyder, Matthew T.; Wetzel, Robert G.

    2009-01-01

    Nanomolar concentrations of steroid hormones such as 17β-estradiol can influence the reproductive development and sex ratios of invertebrate and vertebrate populations. Thus their release into surface and ground waters from wastewater facilities and agricultural applications of animal waste is of environmental concern. Many of these compounds are chromophoric and susceptible to photolytic degradation. High intensity UV-C radiation has been demonstrated to degrade some of these compounds in engineered systems. However, the degradation efficacy of natural solar radiation in shallow fresh waters is less understood. Here photolytic experiments with 17β-estradiol demonstrated modest photodegradation (∼ 26%) when exposed to simulated sunlight between 290 and 720 nm. Photodegradation significantly increased (∼ 40-50%) in the presence of 2.0-15.0 mg/l of dissolved organic carbon (DOC) derived from humic acids of the Suwannee River, GA. However, rates of photodegradation reached a threshold at approximately 5.0 mg/l DOC. Observed suppression of photolysis in the presence of a radical inhibitor (i.e. 2-propanol) indicated that a significant proportion of the degradation was due to radicals formed from the photolysis of DOC. Although photodegradation was greatest in full sunlight containing UV-B (290-320 nm), degradation was also detected with UV-A (320-400 nm) and visible light (400-720 nm) alone

  6. A pathway for sustainable conversion of sunlight to hydrogen using proposed compact CPV system

    KAUST Repository

    Burhan, Muhammad; Shahzad, Muhammad Wakil; Oh, Seung Jin; Ng, Kim Choon

    2018-01-01

    Solar energy being intermittent in nature, can provide a sustainable, steady and high density energy source when converted into electrolytic hydrogen. However, in current photovoltaic market trend with 99% conventional single junction PV panels, this cannot be achieved efficiently and economically. The advent of the multi-junction solar cells (MJCs), with cell-efficiency exceeding 46%, has yet to receive wide spread acceptance in the current PV market in form of concentrated photovoltaic (CPV) system, because of its system design complexity, limiting its application scope and customers. The objective of this paper is to develop a low cost compact CPV system that will not only eliminate its application and installation related restrictions but it is also introducing a highly efficient and sustainable photovoltaic system for common consumer, to convert intermittent sunlight into green hydrogen. The developed CPV system negates the common conviction by showing two times more power output than the flat plate PV, in tropical region. In addition, sunlight to hydrogen conversion efficiency of 18% is recorded for CPV, which is two times higher than alone electricity production efficiency of flat plate PV.

  7. Inactivation and mutation induction in Saccharomyces cerevisiae exposed to simulated sunlight: evaluation of action spectra.

    Science.gov (United States)

    Schenk-Meuser, K; Pawlowsky, K; Kiefer, J

    1992-07-15

    The effectiveness of polychromatic light irradiation was investigated for haploid yeast cells. Inactivation and mutation induction were measured in both a RAD-wildtype strain and an excision-repair defective strain. The behaviour of vegetative "wet" cells was compared to that of dehydrated cells. The aim of the study was to assess the interaction of UVC with other wavelengths in cells of different states of humidity. The irradiation procedure was therefore carried out using a solar simulator either with full spectrum or with a UVC-blocking filter (modified sunlight) added. The results were analysed on the basis of separately determined action spectra. The summation of the efficiency of individual wavelengths was compared to the values obtained from polychromatic irradiation. It is shown that the effects caused by the whole-spectrum irradiation in wet cells can be predicted sufficiently from the calculation, while dried wildtype cells exhibit higher mutation rates. Thus it can be assumed that drying-specific damage leads to lethal and mutagenic lesions which are processed in different ways, causing a synergistic behaviour in mutation induction. Irradiation of vegetative cells with modified sunlight (UVC-) results in less inactivation and lower mutation rates than were calculated. From these results it can be concluded that this antagonistic behaviour is caused by the interaction of near-UV photoproducts.

  8. Prevalence and sunlight photolysis of controlled and chemotherapeutic drugs in aqueous environments

    International Nuclear Information System (INIS)

    Lin, Angela Yu-Chen; Lin, Yen-Ching; Lee, Wan-Ning

    2014-01-01

    This study addresses the occurrences and natural fates of chemotherapeutics and controlled drugs when found together in hospital effluents and surface waters. The results revealed the presence of 11 out of 16 drugs in hospital effluents, and the maximum detected concentrations were at the μg L −1 level in the hospital effluents and the ng L −1 level in surface waters. The highest concentrations corresponded to meperidine, morphine, 5-fluorouracil and cyclophosphamide. The sunlight photolysis of the target compounds was investigated, and the results indicated that morphine and codeine can be significantly attenuated, with half-lives of 0.27 and 2.5 h, respectively, in natural waters. Photolysis can lower the detected environmental concentrations, also lowering the estimated environmental risks of the target drugs to human health. Nevertheless, 5-fluorouracil and codeine were found to have a high risk quotient (RQ), demonstrating the high risks of directly releasing hospital wastewater into the environment. - Highlights: • High occurrence of chemotherapeutics and controlled substances in aqueous systems. • Photolysis lowers the detected concentrations of morphine and codeine. • 5-fluorouracil and codeine in hospital effluents have high risk quotients. - Chemotherapeutics and controlled drugs occur at significant levels in hospital effluents and surface waters. Natural sunlight photolysis reduces their environmental occurrence

  9. Sunlight triggers cutaneous lupus through a CSF-1-dependent mechanism in MRL-Fas(lpr) mice.

    Science.gov (United States)

    Menke, Julia; Hsu, Mei-Yu; Byrne, Katelyn T; Lucas, Julie A; Rabacal, Whitney A; Croker, Byron P; Zong, Xiao-Hua; Stanley, E Richard; Kelley, Vicki R

    2008-11-15

    Sunlight (UVB) triggers cutaneous lupus erythematosus (CLE) and systemic lupus through an unknown mechanism. We tested the hypothesis that UVB triggers CLE through a CSF-1-dependent, macrophage (Mø)-mediated mechanism in MRL-Fas(lpr) mice. By constructing mutant MRL-Fas(lpr) strains expressing varying levels of CSF-1 (high, intermediate, none), and use of an ex vivo gene transfer to deliver CSF-1 intradermally, we determined that CSF-1 induces CLE in lupus-susceptible MRL-Fas(lpr) mice, but not in lupus-resistant BALB/c mice. UVB incites an increase in Møs, apoptosis in the skin, and CLE in MRL-Fas(lpr), but not in CSF-1-deficient MRL-Fas(lpr) mice. Furthermore, UVB did not induce CLE in BALB/c mice. Probing further, UVB stimulates CSF-1 expression by keratinocytes leading to recruitment and activation of Møs that, in turn, release mediators, which induce apoptosis in keratinocytes. Thus, sunlight triggers a CSF-1-dependent, Mø-mediated destructive inflammation in the skin leading to CLE in lupus-susceptible MRL-Fas(lpr) but not lupus-resistant BALB/c mice. Taken together, CSF-1 is envisioned as the match and lupus susceptibility as the tinder leading to CLE.

  10. Sunlight exposure and sun sensitivity associated with disability progression in multiple sclerosis.

    Science.gov (United States)

    D'hooghe, M B; Haentjens, P; Nagels, G; Garmyn, M; De Keyser, J

    2012-04-01

    Sunlight and vitamin D have been inversely associated with the risk of multiple sclerosis (MS). We investigated sunlight exposure and sun sensitivity in relation to disability progression in MS. We conducted a survey among persons with MS, registered by the Flemish MS society, Belgium, and stratified data according to relapsing-onset and progressive-onset MS. We used Kaplan-Meier survival and Cox proportional hazard regression analyses with time to Expanded Disability Status Scale (EDSS) 6 as outcome measure. Hazard ratios for the time from onset and from birth were calculated for the potentially predictive variables, adjusting for age at onset, gender and immunomodulatory treatment. 704 (51.3%) of the 1372 respondents had reached EDSS 6. In relapsing-onset MS, respondents reporting equal or higher levels of sun exposure than persons of the same age in the last 10 years had a decreased risk of reaching EDSS 6. In progressive-onset MS, increased sun sensitivity was associated with an increased hazard of reaching EDSS 6. The association of higher sun exposure with a better outcome in relapsing-onset MS may be explained by either a protective effect or reverse causality. Mechanisms underlying sun sensitivity might influence progression in progressive-onset MS.

  11. Natural organic matter and sunlight accelerate the degradation of 17ss-estradiol in water

    Energy Technology Data Exchange (ETDEWEB)

    Leech, Dina M. [Institute of Marine Sciences, University of North Carolina at Chapel Hill, 3431 Arendell Street, Morehead City, NC 28557 (United States)], E-mail: dmleech@email.unc.edu; Snyder, Matthew T.; Wetzel, Robert G. [Department of Environmental Sciences and Engineering, School of Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 (United States)

    2009-03-01

    Nanomolar concentrations of steroid hormones such as 17{beta}-estradiol can influence the reproductive development and sex ratios of invertebrate and vertebrate populations. Thus their release into surface and ground waters from wastewater facilities and agricultural applications of animal waste is of environmental concern. Many of these compounds are chromophoric and susceptible to photolytic degradation. High intensity UV-C radiation has been demonstrated to degrade some of these compounds in engineered systems. However, the degradation efficacy of natural solar radiation in shallow fresh waters is less understood. Here photolytic experiments with 17{beta}-estradiol demonstrated modest photodegradation ({approx} 26%) when exposed to simulated sunlight between 290 and 720 nm. Photodegradation significantly increased ({approx} 40-50%) in the presence of 2.0-15.0 mg/l of dissolved organic carbon (DOC) derived from humic acids of the Suwannee River, GA. However, rates of photodegradation reached a threshold at approximately 5.0 mg/l DOC. Observed suppression of photolysis in the presence of a radical inhibitor (i.e. 2-propanol) indicated that a significant proportion of the degradation was due to radicals formed from the photolysis of DOC. Although photodegradation was greatest in full sunlight containing UV-B (290-320 nm), degradation was also detected with UV-A (320-400 nm) and visible light (400-720 nm) alone.

  12. Infrastructure Improvements for Snowmelt Runoff Forecasting and Assessments of Climate Change Impacts on Water Supplies in the Rio Grande Basin

    Science.gov (United States)

    Rango, A.; Steele, C. M.; Demouche, L.

    2009-12-01

    In the Southwest US, the southern Rocky Mountains provide a significant orographic barrier to prevailing moisture-laden Westerly winds, which results in snow accumulation and melt, both vitally important to the region’s water resources. The inherent variability of meteorological conditions in the Southwest, during both snowpack buildup and depletion, requires improved spatially-distributed data. The population of ground-based networks (SNOTEL, SCAN, and weather stations) is sparse and does not satisfactorily represent the variability of snow accumulation and melt. Remote sensing can be used to supplement data from ground networks, but the most frequently available remotely sensed product with the highest temporal and spatial resolution, namely snow cover, only provides areal data and not snow volume. Fortunately, the Snowmelt Runoff Model(SRM), which was developed in mountainous regions of the world, including the Rio Grande basin, accepts snow covered area as one of its major input variables along with temperature and precipitation. With the growing awareness of atmospheric warming and the southerly location of Southwest watersheds, it has become apparent that the effects of climate change will be especially important for Southwestern water users. The NSF-funded EPSCoR project “Climate Change Impacts on New Mexico’s Mountain Sources of Water” (started in 2009) has focused on improving hydrometeorological measurements, developing basin-wide and sub-basin snow cover mapping methods, generating snowmelt runoff simulations, forecasts, and long-term climate change assessments, and informing the public of the results through outreach and educational activities. Five new SNOTEL and four new SCAN sites are being installed in 2009-2010 and 12 existing basic SNOTEL sites are being upgraded. In addition, 30 automated precipitation gages are being added to New Mexico measurement networks. The first phase of snow mapping and modeling has focused on four sub basins

  13. Timing of Seasonal Sales.

    OpenAIRE

    Courty, Pascal; Li, Hao

    1999-01-01

    We present a model of timing of seasonal sales where stores choose several designs at the beginning of the season without knowing wich one, if any, will be fashionable. Fashionable designs have a chance to fetch high prices in fashion markets while non-fashionable ones must be sold in a discount market. In the beginning of the season, stores charge high prices in the hope of capturing their fashion market. As the end of the season approaches with goods still on the shelves, stores adjust down...

  14. Effect of sunlight irradiation on photocatalytic pyrene degradation in contaminated soils by micro-nano size TiO2

    International Nuclear Information System (INIS)

    Chang Chien, S.W.; Chang, C.H.; Chen, S.H.; Wang, M.C.; Madhava Rao, M.; Satya Veni, S.

    2011-01-01

    The enhanced catalytic pyrene degradation in quartz sand and alluvial and red soils by micro-nano size TiO 2 in the presence and absence of sunlight was investigated. The results showed that the synergistic effect of sunlight irradiation and TiO 2 was more efficient on pyrene degradation in quartz sand and red and alluvial soils than the corresponding reaction system without sunlight irradiation. In the presence of sunlight irradiation, the photooxidation (without TiO 2 ) of pyrene was very pronounced in alluvial and red soils and especially in quartz sand. However, in the absence of sunlight irradiation, the catalytic pyrene degradation by TiO 2 and the photooxidation (without TiO 2 ) of pyrene were almost nil. This implicates that ultra-violet (UV) wavelength range of sunlight plays an important role in TiO 2 -enhanced photocatalytic pyrene degradation and in photooxidation (without TiO 2 ) of pyrene. The percentages of photocatalytic pyrene degradation by TiO 2 in quartz sand, alluvial and red soils under sunlight irradiation were 78.3, 23.4, and 31.8%, respectively, at 5 h reaction period with a 5% (w/w) dose of the amended catalyst. The sequence of TiO 2 -enhanced catalytic pyrene degradation in quartz sand and alluvial and red soils was quartz sand > red soil > alluvial soil, due to different texture and total organic carbon (TOC) contents of the quartz sand and other two soils. The differential Fourier transform infrared (FT-IR) spectra of degraded pyrene in alluvial soil corroborate that TiO 2 -enhanced photocatalytic degradation rate of degraded pyrene was much greater than photooxidation (without TiO 2 ) rate of degraded pyrene. Based on the data obtained, the importance for the application of TiO 2 -enhanced photocatalytic pyrene degradation and associated organic contaminants in contaminated soils was elucidated. - Highlights: → Synergistic effect of sunlight irradiation and TiO 2 promoted degradation of pyrene. → Micro-nano size TiO 2 enhanced

  15. Interannual Variability in Radiative Forcing and Snowmelt Rates by Desert Dust in Snowcover in the Colorado River Basin

    Science.gov (United States)

    Skiles, S.; Painter, T. H.; Barrett, A. P.; Landry, C.; Deems, J. S.; Winstral, A. H.

    2010-12-01

    Dust in snow accelerates snowmelt through its direct reduction of albedo and its further reduction of albedo by accelerating the growth of snow effective grain size. Since the Anglo expansion and disturbance of the western US that began in the mid 19th century, the mountain snow cover of the Colorado River Basin has been subject to five-fold greater dust loading. This research expands on the work done in Painter et al. (2007) by assessing the interannual variability in radiative forcing, melt rates, and shortening of snow cover duration from 2005 to 2010, and the relative response of melt rates to simulated increases in air temperature. We ran the SNOBAL snowmelt model over the 6 year energy balance record at the alpine and subalpine towers in the Senator Beck Basin Study Area, San Juan Mountains, Colorado, USA. Observations indicate that dust concentrations are not correlated with total number of dust events and that dust loading and concentrations vary by an order of magnitude during the 6 year record. Our modeling results indicate that the number of days that dust advances retreat of snow cover and cumulative radiative forcing are linearly related to total dust concentration. Over the 6 years of record we have shown that for all years dust advances melt relative to a clean snowpack, even in lowest dust concentration years melt is advanced by up to 26 days. The greatest dust radiative impact occurred in 2009, when snow cover duration was shortened by 50 days, and the highest observed end of year dust concentrations reduced visible albedo to less than 0.35 during the last three weeks of snowcover. This work also shows that dust radiative forcing has a markedly greater impact on snow cover duration than increases in temperature. In the presence of dust there is little impact from temperature increases of 2 °C and 4 °C (0-4 days) and, in the absence of dust radiative forcing, temperature increases shorten snow cover duration by 5-18 days, compared with the 26

  16. The influence of air temperature inversions on snowmelt and glacier mass-balance simulations, Ammassalik island, SE Greenland

    Energy Technology Data Exchange (ETDEWEB)

    Mernild, Sebastian Haugard [Los Alamos National Laboratory; Liston, Glen [COLORADO STATE UNIV.

    2009-01-01

    In many applications, a realistic description of air temperature inversions is essential for accurate snow and glacier ice melt, and glacier mass-balance simulations. A physically based snow-evolution modeling system (SnowModel) was used to simulate eight years (1998/99 to 2005/06) of snow accumulation and snow and glacier ice ablation from numerous small coastal marginal glaciers on the SW-part of Ammassalik Island in SE Greenland. These glaciers are regularly influenced by inversions and sea breezes associated with the adjacent relatively low temperature and frequently ice-choked fjords and ocean. To account for the influence of these inversions on the spatiotemporal variation of air temperature and snow and glacier melt rates, temperature inversion routines were added to MircoMet, the meteorological distribution sub-model used in SnowModel. The inversions were observed and modeled to occur during 84% of the simulation period. Modeled inversions were defined not to occur during days with strong winds and high precipitation rates due to the potential of inversion break-up. Field observations showed inversions to extend from sea level to approximately 300 m a.s.l., and this inversion level was prescribed in the model simulations. Simulations with and without the inversion routines were compared. The inversion model produced air temperature distributions with warmer lower elevation areas and cooler higher elevation areas than without inversion routines due to the use of cold sea-breeze base temperature data from underneath the inversion. This yielded an up to 2 weeks earlier snowmelt in the lower areas and up to 1 to 3 weeks later snowmelt in the higher elevation areas of the simulation domain. Averaged mean annual modeled surface mass-balance for all glaciers (mainly located above the inversion layer) was -720 {+-} 620 mm w.eq. y{sup -1} for inversion simulations, and -880 {+-} 620 mm w.eq. y{sup -1} without the inversion routines, a difference of 160 mm w.eq. y

  17. Application of global datasets for hydrological modelling of a remote, snowmelt driven catchment in the Canadian Sub-Arctic

    Science.gov (United States)

    Casson, David; Werner, Micha; Weerts, Albrecht; Schellekens, Jaap; Solomatine, Dimitri

    2017-04-01

    Hydrological modelling in the Canadian Sub-Arctic is hindered by the limited spatial and temporal coverage of local meteorological data. Local watershed modelling often relies on data from a sparse network of meteorological stations with a rough density of 3 active stations per 100,000 km2. Global datasets hold great promise for application due to more comprehensive spatial and extended temporal coverage. A key objective of this study is to demonstrate the application of global datasets and data assimilation techniques for hydrological modelling of a data sparse, Sub-Arctic watershed. Application of available datasets and modelling techniques is currently limited in practice due to a lack of local capacity and understanding of available tools. Due to the importance of snow processes in the region, this study also aims to evaluate the performance of global SWE products for snowpack modelling. The Snare Watershed is a 13,300 km2 snowmelt driven sub-basin of the Mackenzie River Basin, Northwest Territories, Canada. The Snare watershed is data sparse in terms of meteorological data, but is well gauged with consistent discharge records since the late 1970s. End of winter snowpack surveys have been conducted every year from 1978-present. The application of global re-analysis datasets from the EU FP7 eartH2Observe project are investigated in this study. Precipitation data are taken from Multi-Source Weighted-Ensemble Precipitation (MSWEP) and temperature data from Watch Forcing Data applied to European Reanalysis (ERA)-Interim data (WFDEI). GlobSnow-2 is a global Snow Water Equivalent (SWE) measurement product funded by the European Space Agency (ESA) and is also evaluated over the local watershed. Downscaled precipitation, temperature and potential evaporation datasets are used as forcing data in a distributed version of the HBV model implemented in the WFLOW framework. Results demonstrate the successful application of global datasets in local watershed modelling, but

  18. Evolution of concentration-discharge relations revealed by high frequency diurnal sampling of stream water during spring snowmelt

    Science.gov (United States)

    Olshansky, Y.; White, A. M.; Thompson, M.; Moravec, B. G.; McIntosh, J. C.; Chorover, J.

    2017-12-01

    Concentration discharge (C-Q) relations contain potentially important information on critical zone (CZ) processes including: weathering reactions, water flow paths and nutrient export. To examine the C-Q relations in a small (3.3 km2) headwater catchment - La Jara Creek located in the Jemez River Basin Critical Zone Observatory, daily, diurnal stream water samples were collected during spring snow melt 2017, from two flumes located in outlets of the La Jara Creek and a high elevation zero order basin within this catchment. Previous studies from this site (McIntosh et al., 2017) suggested that high frequency sampling was needed to improve our interpretation of C-Q relations. The dense sampling covered two ascending and two descending limbs of the snowmelt hydrograph, from March 1 to May 15, 2017. While Na showed inverse correlation (dilution) with discharge, most other solutes (K, Mg, Fe, Al, dissolved organic carbon) exhibited positive (concentration) or chemostatic trends (Ca, Mn, Si, dissolved inorganic carbon and dissolved nitrogen). Hysteresis in the C-Q relation was most pronounced for bio-cycled cations (K, Mg) and for Fe, which exhibited concentration during the first ascending limb followed by a chemostatic trend. A pulsed increase in Si concentration immediately after the first ascending limb in both flumes suggests mixing of deep groundwater with surface water. A continual increase in Ge/Si concentrations followed by a rapid decrease after the second rising limb may suggest a fast transition between soil water to ground water dominating the stream flow. Fourier transform infrared spectroscopy of selected samples across the hydrograph demonstrated pronounced changes in dissolved organic matter molecular composition with the advancement of the spring snow melt. X-ray micro-spectroscopy of colloidal material isolated from the collected water samples indicated a significant role for organic matter in the transport of inorganic colloids. Analyses of high

  19. Seasonal variation of dystocia in a large Danish cohort.

    Science.gov (United States)

    Rohr Thomsen, Christine; Uldbjerg, Niels; Hvidman, Lone; Atladóttir, Hjördís Ósk; Henriksen, Tine Brink; Milidou, Ioanna

    2014-01-01

    Dystocia is one of the most frequent causes of cesarean delivery in nulliparous women. Despite this, its causes are largely unknown. Vitamin D receptor (VDR) has been found in the myometrium. Thus, it is possible that vitamin D affects the contractility of the myometrium and may be involved in the pathogenesis of dystocia. Seasonal variation of dystocia in areas with distinct seasonal variation in sunlight exposure, like Denmark, could imply that vitamin D may play a role. This study examined whether there was seasonal variation in the incidence of dystocia in a Danish population. We used information from a cohort of 34,261 nulliparous women with singleton pregnancies, spontaneous onset of labor between 37 and 42 completed gestational weeks, and vertex fetal presentation. All women gave birth between 1992 and 2010 at the Department of Obstetrics and Gynecology, Aarhus University Hospital, Skejby. Logistic regression combined with cubic spline was used to estimate the seasonal variation for each outcome after adjusting for calendar time. No evidence for seasonal variation was found for any of the outcomes: acute cesarean delivery due to dystocia (p = 0.44); instrumental vaginal delivery due to dystocia (p = 0.69); oxytocin augmentation due to dystocia (p = 0.46); and overall dystocia (p = 0.91). No seasonal variation in the incidence of dystocia was observed in a large cohort of Danish women. This may reflect no association between vitamin D and dystocia, or alternatively that other factors with seasonal variation and influence on the occurrence of dystocia attenuate such an association.

  20. Fractionation of cesium isotopes and 90Sr in snowmelt run-off and lake waters from a contaminated Norwegian mountain catchment

    International Nuclear Information System (INIS)

    Salbu, B.; Bjoernstad, H.E.; Brittain, J.E.

    1992-01-01

    Cesium isotopes and 90 Sr have been determined in the inflow and outflow rivers of a Norwegian subalpine lake. The lake is situated in an area contaminated by Chernobyl fallout. Sampling was carried out during the spring peak discharge period associated with snowmelt. Transported coarse particulate plant material was collected by traps. Particles and colloids were removed from water samples by hollow fibre ultrafiltration. The results illustrate that run-off during the spring snowmelt is an important pathway for these radionuclides. The cesium isotopes are predominantly transported as colloids, while 90 Sr is present in the form of low molecular weight mobile species. Based on lake budget calculations, more than 50% of the cesium input is retained in the lake, while more than 90% of the 90 Sr is transported through the lake and into lower parts of the drainage system. (author) 16 refs.; 6 figs.; 3 tabs

  1. Snow-melt flood frequency analysis by means of copula based 2D probability distributions for the Narew River in Poland

    Directory of Open Access Journals (Sweden)

    Bogdan Ozga-Zielinski

    2016-06-01

    New hydrological insights for the region: The results indicated that the 2D normal probability distribution model gives a better probabilistic description of snowmelt floods characterized by the 2-dimensional random variable (Qmax,f, Vf compared to the elliptical Gaussian copula and Archimedean 1-parameter Gumbel–Hougaard copula models, in particular from the view point of probability of exceedance as well as complexity and time of computation. Nevertheless, the copula approach offers a new perspective in estimating the 2D probability distribution for multidimensional random variables. Results showed that the 2D model for snowmelt floods built using the Gumbel–Hougaard copula is much better than the model built using the Gaussian copula.

  2. Seasonal Accumulation and Depletion of Local Sediment Stores of Four Headwater Catchments

    Directory of Open Access Journals (Sweden)

    Sarah E. Martin

    2014-07-01

    Full Text Available Seasonal turbidity patterns and event-level hysteresis analysis of turbidity verses discharge in four 1 km2 headwater catchments in California’s Sierra Nevada indicate localized in-channel sediment sources and seasonal accumulation-depletion patterns of stream sediments. Turbidity signals were analyzed for three years in order to look at the relationships between seasonal turbidity trends, event turbidity patterns, and precipitation type to stream sediment production and transport. Seasonal patterns showed more turbidity events associated with fall and early to mid- winter events than with peak snow-melt. No significant turbidity patterns emerged for periods of snow melt vs. rain. Single event hysteresis loops showed clockwise patterns were dominant suggesting local sediment sources. In successive discharge events, the largest turbidity spike was often associated with the first but not necessarily the largest discharge event-indicating seasonal depletion of local sediment stores. In multi-peaked discharge events, hysteresis loops shifted from clockwise to linear or random patterns suggesting that localized sediment stores are being used up and sufficient flow energy must be reached to start entraining the more consolidated bank/bed sediment or that dominant sediment sources may be shifting to less localized areas such as hill slopes. A conceptual model with phases of accumulation and transport is proposed.

  3. Hydrological response to dynamical downscaling of climate model outputs: A case study for western and eastern snowmelt-dominated Canada catchments

    OpenAIRE

    Magali Troin; Daniel Caya; Juan Alberto Velázquez; François Brissette

    2015-01-01

    Study region: An analysis of hydrological response to a dynamically downscaled multi-member multi-model global climate model (GCM) ensemble of simulations based on the Canadian Regional Climate Model (CRCM) is presented for three snowmelt-dominated basins in Canada. The basins are situated in the western mountainous (British Columbia) and eastern level (Quebec) regions in Canada, providing comprehensive experiments to validate the CRCM over various topographic features. Study focus: The ev...

  4. Executive summary - Assessing the response of Emerald Lake, an alpine watershed in Sequoia National Park, California, to acidification during snowmelt using a simple hydrochemical model

    International Nuclear Information System (INIS)

    Hooper, R.P.; West, C.T.; Peters, N.E.

    1990-01-01

    A simple process-oriented model, called the Alpine Lake Forecaster (ALF), was constructed using data collected from the Integrated Watershed Study of Emerald Lake, Sequoia National Park, California. ALF is able to capture the basic solute patterns during snowmelt in this alpine catchment where groundwater is a minor contributor to streamflow. It includes an empirical representation of primary mineral weathering as the only alkalinity generating mechanism. During a heavy snow year, such as the one used for calibrating the model, the model accurately simulated the surface water chemical change in response to the initial ionic pulse from the snowpack and to the dilution that occurs at peak snowmelt. Because the model does not consider cation exchange, it over-predicts the acidification during the initial period of snowmelt, and therefore is a conservative predictor. However, the minimum alkalinity observed in the main inflows to Emerald Lake and in the lake outflow is accurately simulated by the model. The representation of the lake as simply a missing volume with no additional chemical reactions is supported by the observation. The model predicts a change of 2 to 5 microequiv/L in the minimum alkalinity of the lake outflow during snowmelt if the deposition would have to increase between two and 18 times the current load-alkalinity of the lake; the precise increase depends on hydrologic conditions and on the pattern of solute release from the snowpack. An acidic rainstorm that exhausted the alkalinity of the lake was observed during summer 1984 after the lake had stratified, and is the likely cause of the acidification of Emerald Lake

  5. Study of critical free-area ratio during the snow-melting process on pavement using low-temperature heating fluids

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Huajun [School of Energy and Environment Engineering, Hebei University of Technology, Tianjin 300401 (China); Chen, Zhihao [Faculty of Engineering, Yokohama National University, Hodogaya, Yokohama 240-8501 (Japan)

    2009-01-15

    Critical free-area ratio (CFR) is an interesting phenomenon during the snow-melting process on pavement using low-temperature heating fluids such as geothermal tail water and industrial waste water. This paper is performed to further investigate the mechanism of CFR and its influencing factors. A simplified theoretical model is presented to describe the heat and mass transfer process on pavement. Especially the variation of thermal properties and the capillary effect of snow layer are considered. Numerical computation shows that the above theoretical model is effective for the prediction of CFR during the snow-melting process. Furthermore, the mechanism of CFR is clarified in detail. CFR is independent of the layout of hydronic pipes, the fluid temperature, the idling time, and weather conditions. It is both the non-uniform temperature distribution and complicated porous structure of snow layer that lead to the occurrence of CFR. Besides, the influences of operation parameters including the fluid temperature, the idling time, the pipe spacing and buried depths on snow melting are analyzed, which are helpful for the next optimal design of snow-melting system. (author)

  6. Study of critical free-area ratio during the snow-melting process on pavement using low-temperature heating fluids

    Energy Technology Data Exchange (ETDEWEB)

    Wang Huajun [School of Energy and Environment Engineering, Hebei University of Technology, Tianjin 300401 (China)], E-mail: huajunwang@126.com; Chen Zhihao [Faculty of Engineering, Yokohama National University, Hodogaya, Yokohama 240-8501 (Japan)

    2009-01-15

    Critical free-area ratio (CFR) is an interesting phenomenon during the snow-melting process on pavement using low-temperature heating fluids such as geothermal tail water and industrial waste water. This paper is performed to further investigate the mechanism of CFR and its influencing factors. A simplified theoretical model is presented to describe the heat and mass transfer process on pavement. Especially the variation of thermal properties and the capillary effect of snow layer are considered. Numerical computation shows that the above theoretical model is effective for the prediction of CFR during the snow-melting process. Furthermore, the mechanism of CFR is clarified in detail. CFR is independent of the layout of hydronic pipes, the fluid temperature, the idling time, and weather conditions. It is both the non-uniform temperature distribution and complicated porous structure of snow layer that lead to the occurrence of CFR. Besides, the influences of operation parameters including the fluid temperature, the idling time, the pipe spacing and buried depths on snow melting are analyzed, which are helpful for the next optimal design of snow-melting system.

  7. Study of critical free-area ratio during the snow-melting process on pavement using low-temperature heating fluids

    International Nuclear Information System (INIS)

    Wang Huajun; Chen Zhihao

    2009-01-01

    Critical free-area ratio (CFR) is an interesting phenomenon during the snow-melting process on pavement using low-temperature heating fluids such as geothermal tail water and industrial waste water. This paper is performed to further investigate the mechanism of CFR and its influencing factors. A simplified theoretical model is presented to describe the heat and mass transfer process on pavement. Especially the variation of thermal properties and the capillary effect of snow layer are considered. Numerical computation shows that the above theoretical model is effective for the prediction of CFR during the snow-melting process. Furthermore, the mechanism of CFR is clarified in detail. CFR is independent of the layout of hydronic pipes, the fluid temperature, the idling time, and weather conditions. It is both the non-uniform temperature distribution and complicated porous structure of snow layer that lead to the occurrence of CFR. Besides, the influences of operation parameters including the fluid temperature, the idling time, the pipe spacing and buried depths on snow melting are analyzed, which are helpful for the next optimal design of snow-melting system

  8. Assessment of future climate change impacts on nonpoint source pollution in snowmelt period for a cold area using SWAT.

    Science.gov (United States)

    Wang, Yu; Bian, Jianmin; Zhao, Yongsheng; Tang, Jie; Jia, Zhuo

    2018-02-05

    The source area of Liao River is a typical cold region in northeastern China, which experiences serious problems with agricultural nonpoint source pollution (NPS), it is important to understand future climate change impacts on NPS in the watershed. This issue has been investigated by coupling semi distributed hydrological model (SWAT), statistical downscaling model (SDSM) and global circulation model (GCMs). The results show that annual average temperature would rise by 2.1 °C (1.3 °C) in the 2080 s under scenario RCP8.5 (RCP4.5), and annual precipitation would increase by 67 mm (33 mm). The change in winter temperature and precipitation is most significant with an increase by 0.23 °C/10a (0.17 °C/10a) and 1.94 mm/10a (2.78 mm/10a). The future streamflow, TN and TP loads would decrease by 19.05% (10.59%), 12.27% (8.81%) and 10.63% (6.11%), respectively. Monthly average streamflow, TN and TP loads would decrease from March to November, and increase from December to February. This is because the increased precipitation and temperature in winter, which made the spring snowpack melting earlier. These study indicate the trends of nonpoint source pollution during the snowmelt period under climate change conditions, accordingly adaptation measures will be necessary.

  9. Long-wave Irradiance Measurement and Modeling during Snowmelt, a Case Study in the Yukon Territory, Canada

    Science.gov (United States)

    Sicart, J.; Essery, R.; Pomeroy, J.

    2004-12-01

    At high latitudes, long-wave radiation emitted by the atmosphere and solar radiation can provide similar amounts of energy for snowmelt due to the low solar elevation and the high albedo of snow. This paper investigates temporal and spatial variations of long-wave irradiance at the snow surface in an open sub-Arctic environment. Measurements were conducted in the Wolf Creek Research Basin, Yukon Territory, Canada (60°36'N, 134°57'W) during the springs of 2002, 2003 and 2004. The main causes of temporal variability are air temperature and cloud cover, especially in the beginning of the melting period when the atmosphere is still cold. Spatial variability was investigated through a sensitivity study to sky view factors and to temperatures of surrounding terrain. The formula of Brutsaert gives a useful estimation of the clear-sky irradiance at hourly time steps. Emission by clouds was parameterized at the daily time scale from the atmospheric attenuation of solar radiation. The inclusion of air temperature variability does not much improve the calculation of cloud emission.

  10. Recent ice cap snowmelt in Russian High Arctic and anti-correlation with late summer sea ice extent

    International Nuclear Information System (INIS)

    Zhao, Meng; Ramage, Joan; Semmens, Kathryn; Obleitner, Friedrich

    2014-01-01

    Glacier surface melt dynamics throughout Novaya Zemlya (NovZ) and Severnaya Zemlya (SevZ) serve as a good indicator of ice mass ablation and regional climate change in the Russian High Arctic. Here we report trends of surface melt onset date (MOD) and total melt days (TMD) by combining multiple resolution-enhanced active and passive microwave satellite datasets and analyze the TMD correlations with local temperature and regional sea ice extent. The glacier surface snowpack on SevZ melted significantly earlier (−7.3 days/decade) from 1992 to 2012 and significantly longer (7.7 days/decade) from 1995 to 2011. NovZ experienced large interannual variability in MOD, but its annual mean TMD increased. The snowpack melt on NovZ is more sensitive to temperature fluctuations than SevZ in recent decades. After ruling out the regional temperature influence using partial correlation analysis, the TMD on both archipelagoes is statistically anti-correlated with regional late summer sea ice extent, linking land ice snowmelt dynamics to regional sea ice extent variations. (letter)

  11. Modelling of seasonal dynamics of Wetland-Groundwater flow interaction in the Canadian Prairies

    Science.gov (United States)

    Ali, Melkamu; Nussbaumer, Raphaël; Ireson, Andrew; Keim, Dawn

    2015-04-01

    Wetland-shallow groundwater interaction is studied at the St. Denis National Wildlife Area in Saskatchewan, Canada, located within the northern glaciated prairies of North America. Ponds in the Canadian Prairies are intermittently connected by fill-spill processes in the spring and growing season of some wetter years. The contribution of the ponds and wetlands to groundwater is still a significant research challenge. The objective of this study is to evaluate model's ability to reproduce observed effects of groundwater-wetland interactions including seasonal pattern of shallow groundwater table, intended flow direction and to quantify the depression induced infiltration from the wetland to the surrounding uplands. The integrated surface-wetland-shallow groundwater processes and the changes in land-energy and water balances caused by the flow interaction are simulated using ParFlow-CLM at a small watershed of 1km2 containing both permanent and seasonal wetland complexes. We compare simulated water table depth with piezometers reading monitored by level loggers at the watershed. We also present the strengths and limitations of the model in reproducing observed behaviour of the groundwater table response to the spring snowmelt and summer rainfall. Simulations indicate that the shallow water table at the uphill recovers quickly after major rainfall events in early summer that generates lateral flow to the pond. In late summer, the wetland supplies water to the surrounding upland when the evapotranspiration is higher than the precipitation in which more water from the root zone is up taken by plants. Results also show that Parflow-CLM is able to reasonably simulate the water table patterns response to summer rainfall, while it is insufficient to reproduce the spring snowmelt infiltration which is the most dominant hydrological process in the Prairies.

  12. Simulation of Snowmelt Runoff Using SRM Model and Comparison With Neural Networks ANN and ANFIS (Case Study: Kardeh dam basin

    Directory of Open Access Journals (Sweden)

    morteza akbari

    2017-03-01

    Full Text Available Introduction: Snowmelt runoff plays an important role in providing water and agricultural resources, especially in mountainous areas. There are different methods to simulate the process of snowmelt. Inter alia, degree-day model, based on temperature-index is more cited. Snowmelt Runoff Model is a conceptual hydrological model to simulate and predict the daily flow of rivers in the mountainous basins on the basis of comparing the accuracy of AVHRR and TM satellite images to determine snow cover in Karun Basin. Additionally, overestimation of snow-covered area decreased with increasing spatial resolution of satellite data.Studies conducted in the Zayandehrood watershed dam, showed that in the calculation of the snow map cover, changes from MODIS satellite imagery, at the time that the image does not exist, using the digital elevation model and regression analysis can provide to estimate the appropriate data from satellites. In the study of snow cover in eastern Turkey, in the mountainous regions of the Euphrates River, data from five meteorological stations and MODIS images were used with a resolution of 500 m. The results showed that satellite images have a good accuracy in estimating snow cover. In a Watershed in northern Pakistan in the period from 2000 to 2006, SRM model was used to estimate the snow cover using MODIS images. The purpose of this study was to evaluate the snowmelt runoff using remote sensing data and SRM model for flow simulation, based on statistical parameters in the Kardeh dam basin. Materials and Methods: Kardeh dam basin has an area of about 560 square kilometers and is located in the north of Mashhad. This area is in the East of Hezarmasjed – kopehdagh zone that is one of the main basins of Kashafrood. This basin is a mountainous area. About 261 km of the basin is located at above 2000 m. The lowest point of the basin is at the watershed outlet with1300 meters and the highest point in the basin, in the North West part

  13. Graphene-SnO2 composites for highly efficient photocatalytic degradation of methylene blue under sunlight.

    Science.gov (United States)

    Seema, Humaira; Christian Kemp, K; Chandra, Vimlesh; Kim, Kwang S

    2012-09-07

    Graphene sheets decorated with SnO(2) nanoparticles (RGO-SnO(2)) were prepared via a redox reaction between graphene oxide (GO) and SnCl(2). Graphene oxide (GO) was reduced to graphene (RGO) and Sn(2+) was oxidized to SnO(2) during the redox reaction, leading to a homogeneous distribution of SnO(2) nanoparticles on RGO sheets. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images show uniform distribution of the nanoparticles on the RGO surface and high-resolution transmission electron microscopy (HRTEM) shows an average particle size of 3-5 nm. The RGO-SnO(2) composite showed an enhanced photocatalytic degradation activity for the organic dye methylene blue under sunlight compared to bare SnO(2) nanoparticles. This result leads us to believe that the RGO-SnO(2) composite could be used in catalytic photodegradation of other organic dyes.

  14. Sunlight effects on the 3D polar current system determined from low Earth orbit measurements

    DEFF Research Database (Denmark)

    Laundal, Karl M.; Finlay, Chris; Olsen, Nils

    2016-01-01

    Interaction between the solar wind and the Earth’s magnetosphere is associated with large-scale currents in the ionosphere at polar latitudes that flow along magnetic field lines (Birkeland currents) and horizontally. These current systems are tightly linked, but their global behaviors are rarely...... analyzed together. In this paper, we present estimates of the average global Birkeland currents and horizontal ionospheric currents from the same set of magnetic field measurements. The magnetic field measurements, from the low Earth orbiting Swarm and CHAMP satellites, are used to co-estimate poloidal...... and toroidal parts of the magnetic disturbance field, represented in magnetic apex coordinates. The use of apex coordinates reduces effects of longitudinal and hemispheric variations in the Earth’s main field. We present global currents from both hemispheres during different sunlight conditions. The results...

  15. On the apparent velocity of integrated sunlight. I - 1983-1985

    Science.gov (United States)

    Deming, Drake; Espenak, Fred; Jennings, Donald E.; Brault, James W.; Wagner, Jeremy

    1987-01-01

    Frequency measurements for the Delta V = 2 transitions of CO in the integrated light spectrum of the sun are presented. The nature and magnitude of systematic errors which typically arise in absolute velocity measurements of integrated sunlight are explored in some detail, and measurements believed accurate at the level of about 5 m/s or less are presented. It is found that the integrated light velocity varies by about 3 m/s or less over a one-day period. Over the long term, the data indicate an increasing blue-shift in these weak infrared lines amounting to 30 m/s from 1983 to 1985. The sense of the drift is consistent with a lessening in the magnetic inhibition of granular convection at solar minimum. Such an effect has implications for the spectroscopic detectability of planetary-mass companions to solar-type stars.

  16. Type II GaSb quantum ring solar cells under concentrated sunlight.

    Science.gov (United States)

    Tsai, Che-Pin; Hsu, Shun-Chieh; Lin, Shih-Yen; Chang, Ching-Wen; Tu, Li-Wei; Chen, Kun-Cheng; Lay, Tsong-Sheng; Lin, Chien-Chung

    2014-03-10

    A type II GaSb quantum ring solar cell is fabricated and measured under the concentrated sunlight. The external quantum efficiency confirms the extended absorption from the quantum rings at long wavelength coinciding with the photoluminescence results. The short-circuit current of the quantum ring devices is 5.1% to 9.9% more than the GaAs reference's under various concentrations. While the quantum ring solar cell does not exceed its GaAs counterpart in efficiency under one-sun, the recovery of the open-circuit voltages at higher concentration helps to reverse the situation. A slightly higher efficiency (10.31% vs. 10.29%) is reported for the quantum ring device against the GaAs one.

  17. Degradation of 4-Chlorophenol Under Sunlight Using ZnO Nanoparticles as Catalysts

    Science.gov (United States)

    Rajar, Kausar; Sirajuddin; Balouch, Aamna; Bhanger, M. I.; Sherazi, Tufail H.; Kumar, Raj

    2018-03-01

    Herein we demonstrate a simplistic microwave assisted chemical precipitation approach regarding the synthesis of zinc oxide nanoparticles. As-prepared ZnO nanoparticles (NPs) were characterized by UV-visible spectroscopy, Fourier transform infra-red spectroscopy, atomic force microscopy and x-ray diffractometry and scrutinized as photo-catalysts for degradation of 4-chlorophenol (4-CP) under sunlight. The study substantiated that 98.5% of 4-CP was degraded within 20 min in the absence of initiator like H2O2 which reflects an outstanding prospective use for ZnO NPs as photo-catalysts. The nanocatalysts were recycled four times and still showed catalytic efficiency up to 95.5% for degradation of 4-CP in the specified 20 min.

  18. Sunlight-assisted synthesis of colloidal silver nanoparticles using chitosan as reducing agent

    Science.gov (United States)

    Susilowati, E.; Maryani; Ashadi

    2018-04-01

    The present study we explore an environmentally friendly colloidal silver nanoparticles preparation using chitosan as reducing agent and stabilizer. It develops a new strategy on preparation of silver nanoparticles through the gel phase using sodium hydroxide (NaOH) as accelerator reagent. Sunlight irradiation was employed to assisted reducing process of silver ions to silver nanoparticles. Localized surface plasmon resonance (LSPR) phenomenon of silver nanoparticles was investigated using UV-Vis spectrophotometer. The shape and size of silver particles were analyzed using TEM. The formation of silver nanoparticles was confirmed by the appearance of LSPR absorption peak at 396.0–412.0 nm. The absorption peak of LSPR were affected by NaOH amount, time of sulight irradiation and concentration of AgNO3. The produced silver nanoparticles were spherical with dominant size range of 5 to 8 nm as shown by TEM images. All colloidals were stable without any aggregation for 30 days after preparation.

  19. Recovery of hexavalent chromium from water using photoactive TiO2-montmorillonite under sunlight

    Directory of Open Access Journals (Sweden)

    Ridha Djellabi

    2016-04-01

    Full Text Available Hexavalent chromium was removed from water under sunlight using a synthesized TiO2-montmorillonite (TiO2-M employing tartaric acid as a hole scavenger. Cr(VI species was then reduced to Cr(III species by electrons arising from TiO2 particles. After that, the produced Cr(III species  was transferred to montmorillonite  due to electrostatic attractions leading to  set free TiO2 particles for a further Cr(VI species reduction. Furthermore, produced Cr(III, after Cr(VI reduction, does not  penetrate into the solution. The results indicate that no dark adsorption of Cr(VI species on TiO2-M is present, however, the reduction of Cr(VI species under sunlight increased strongly as a function of tartaric acid concentration up to 60 ppm, for which the extent of reduction is maximum within 3 h. On the other hand, the reduction extent of Cr(VI species is maximum with an initial concentration of Cr(VI species lower than 30 ppm by the use of 0.2 g/L of TiO2-M. Nevertheless, the increase of the Cr(VI initial concentration led to increase the amount of Cr(VI species reduced (capacity of reduction until a Cr(VI concentration of 75 and 100 ppm, for which  it remained constant at around 221 mg/g. For comparison, the increase of Cr(VI species concentration in the case of the commercial TiO2 P25 under the same conditions exhibited its deactivation when the reduced amount decreased from 198.1 to 157.6 mg/g as the concentration increased from 75 to 100 ppm.

  20. The relationship between long-term sunlight radiation and cognitive decline in the REGARDS cohort study

    Science.gov (United States)

    Kent, Shia T.; Kabagambe, Edmond K.; Wadley, Virginia G.; Howard, Virginia J.; Crosson, William L.; Al-Hamdan, Mohammad Z.; Judd, Suzanne E.; Peace, Fredrick; McClure, Leslie A.

    2014-04-01

    Sunlight may be related to cognitive function through vitamin D metabolism or circadian rhythm regulation. The analysis presented here sought to test whether ground and satellite measures of solar radiation are associated with cognitive decline. The study used a 15-year residential history merged with satellite and ground monitor data to determine sunlight (solar radiation) and air temperature exposure for a cohort of 19,896 cognitively intact black and white participants aged 45+ from the 48 contiguous United States. Exposures of 15, 10, 5, 2, and 1-year were used to predict cognitive status at the most recent assessment in logistic regression models; 1-year insolation and maximum temperatures were chosen as exposure measures. Solar radiation interacted with temperature, age, and gender in its relationships with incident cognitive impairment. After adjustment for covariates, the odds ratio (OR) of cognitive decline for solar radiation exposure below the median vs above the median in the 3rd tertile of maximum temperatures was 1.88 (95 % CI: 1.24, 2.85), that in the 2nd tertile was 1.33 (95 % CI: 1.09, 1.62), and that in the 1st tertile was 1.22 (95 % CI: 0.92, 1.60). We also found that participants under 60 years old had an OR = 1.63 (95 % CI: 1.20, 2.22), those 60-80 years old had an OR = 1.18 (95 % CI: 1.02, 1.36), and those over 80 years old had an OR = 1.05 (0.80, 1.37). Lastly, we found that males had an OR = 1.43 (95 % CI: 1.22, 1.69), and females had an OR = 1.02 (0.87, 1.20). We found that lower levels of solar radiation were associated with increased odds of incident cognitive impairment.

  1. Sunlight-exposed biofilm microbial communities are naturally resistant to chernobyl ionizing-radiation levels.

    Science.gov (United States)

    Ragon, Marie; Restoux, Gwendal; Moreira, David; Møller, Anders Pape; López-García, Purificación

    2011-01-01

    The Chernobyl accident represents a long-term experiment on the effects of exposure to ionizing radiation at the ecosystem level. Though studies of these effects on plants and animals are abundant, the study of how Chernobyl radiation levels affect prokaryotic and eukaryotic microbial communities is practically non-existent, except for a few reports on human pathogens or soil microorganisms. Environments enduring extreme desiccation and UV radiation, such as sunlight exposed biofilms could in principle select for organisms highly resistant to ionizing radiation as well. To test this hypothesis, we explored the diversity of microorganisms belonging to the three domains of life by cultivation-independent approaches in biofilms developing on concrete walls or pillars in the Chernobyl area exposed to different levels of radiation, and we compared them with a similar biofilm from a non-irradiated site in Northern Ireland. Actinobacteria, Alphaproteobacteria, Bacteroidetes, Acidobacteria and Deinococcales were the most consistently detected bacterial groups, whereas green algae (Chlorophyta) and ascomycete fungi (Ascomycota) dominated within the eukaryotes. Close relatives to the most radio-resistant organisms known, including Rubrobacter species, Deinococcales and melanized ascomycete fungi were always detected. The diversity of bacteria and eukaryotes found in the most highly irradiated samples was comparable to that of less irradiated Chernobyl sites and Northern Ireland. However, the study of mutation frequencies in non-coding ITS regions versus SSU rRNA genes in members of a same actinobacterial operational taxonomic unit (OTU) present in Chernobyl samples and Northern Ireland showed a positive correlation between increased radiation and mutation rates. Our results show that biofilm microbial communities in the most irradiated samples are comparable to non-irradiated samples in terms of general diversity patterns, despite increased mutation levels at the single

  2. On the apparent velocity of integrated sunlight. 2: 1983-1992 and comparisons with magnetograms

    Science.gov (United States)

    Deming, Drake; Plymate, Claude

    1994-01-01

    We report additional results in our program to monitor the wavelength stability of lines in the 2.3 micrometer spectrum of integrated sunlight. We use the McMath Fourier transform spectrometer (FTS) of the National Solar Observatory to monitor 16 delta V = 2 lines of (12)C(16)O, as well as five atomic lines. Wavenumber calibration is achieved using a low-pressure N2O absorption cell and checked against terrestrial atmospheric lines. Imperfect optical integration of the solar disk remains the principal source of error, but this error has been reduced by improved FTS/telescope collimation and observing procedures. The present results include data from an additional 13 quarterly observing runs since 1985. We continue to find that the apparent velocity of integrated sunlight is variable, in the sense of having a greater reshift at solar maximum. This is supported by the temporal dependence of the integrated light velocity, and by the presence of a correlation between velocity and the disk-averaged magnetic flux derived from Kitt Peak magnetograms. The indicated peak-to-peak apparent velocity amplitude over a solar cycle is approximately the same as the velocity amplitude of the Sun's motion about the solar system barycenter. This represents about half the amplitude which we inferred in Paper I (Deming et al. 1987), but the present result has a much greater statistical significance. Our results have implications for those investigations which search for the Doppler signatures of planetary-mass companions to solar-type stars. We contrast our results to the recent finding by McMillan et al. 1993 that solar absorption lines in the violet spectral region are wavelength-stable over the solar cycle.

  3. Molecular and sensory mechanisms to mitigate sunlight-induced DNA damage in treefrog tadpoles.

    Science.gov (United States)

    Schuch, André P; Lipinski, Victor M; Santos, Mauricio B; Santos, Caroline P; Jardim, Sinara S; Cechin, Sonia Z; Loreto, Elgion L S

    2015-10-01

    The increased incidence of solar ultraviolet B (UVB) radiation has been proposed as an environmental stressor, which may help to explain the enigmatic decline of amphibian populations worldwide. Despite growing knowledge regarding the UV-induced biological effects in several amphibian models, little is known about the efficacy of DNA repair pathways. In addition, little attention has been given to the interplay between these molecular mechanisms with other physiological strategies that avoid the damage induced by sunlight. Here, DNA lesions induced by environmental doses of solar UVB and UVA radiation were detected in genomic DNA samples of treefrog tadpoles (Hypsiboas pulchellus) and their DNA repair activity was evaluated. These data were complemented by monitoring the induction of apoptosis in blood cells and tadpole survival. Furthermore, the tadpoles' ability to perceive and escape from UV wavelengths was evaluated as an additional strategy of photoprotection. The results show that tadpoles are very sensitive to UVB light, which could be explained by the slow DNA repair rates for both cyclobutane pyrimidine dimers (CPDs) and pyrimidine (6,4) pyrimidone photoproducts (6,4PPs). However, they were resistant to UVA, probably as a result of the activation of photolyases during UVA irradiation. Surprisingly, a sensory mechanism that triggers their escape from UVB and UVA light avoids the generation of DNA damage and helps to maintain the genomic integrity. This work demonstrates the genotoxic impact of both UVB and UVA radiation on tadpoles and emphasizes the importance of the interplay between molecular and sensory mechanisms to minimize the damage caused by sunlight. © 2015. Published by The Company of Biologists Ltd.

  4. Effect of artificial sunlight on the retention of external calcein marks on lake trout

    Science.gov (United States)

    Honeyfield, D.C.; Kehler, T.; Fletcher, J.W.; Mohler, J.W.

    2008-01-01

    When choosing a fish marking technique to address fishery related questions, it is important to consider factors that affect mark retention. Calcein, a chemical marking agent, is under investigation for potential use on fish. Two laboratory trials were conducted with calcein-marked lake trout Salvelinus namaycush to determine the effect of artificial sunlight on calcein mark intensity. In trial 1, fish exposed to 18,000 lx for 7 d lost 90% or more of the calcein mark intensity (relative to the colorimetric key, mg/L) on the head, body, ventral region, and pectoral fins relative to mark intensity in fish that were maintained in darkness. In trial 2, light intensity was reduced 2.5-3.0-fold. After 7 d of light exposure, calcein mark intensity on the head was reduced by 40-45% relative to mark intensity in fish that were held in darkness; by day 14, calcein mark intensity on the head was reduced by 55-60% relative to that of dark-treated fish. No further decline was observed in light-exposed fish, and head mark intensity values did not differ among days 14, 21, and 28 for this treatment group. Of the four areas evaluated, the head and pectoral fin were more easily read using a colorimetric key than the lateral or ventral regions of the fish. The concentration of calcein spotted on filter paper to devise the colorimetric key ranged from 1 to 100 mg/L. A difference of approximately 7 mg/L in apparent calcein mark intensity means for the head region could be detected using the colorimetric key. These trials showed that calcein mark intensity on lake trout declined when fish were exposed to artificial sunlight, and the use of a colorimetric key improved the objectivity of calcein mark intensity assessment.

  5. Seasonal Variation in Vitamin D Status among Frail Older Hospitalized Patients.

    Science.gov (United States)

    Pourhassan, M; Wirth, R

    2018-01-01

    Seasonal variation in 25-hydroxyvitamin D [25(OH)D] levels is the result of sunlight dependent skin synthesis of vitamin D. However, its presence is not studied in frail older hospitalized patients. We sought to investigate whether seasonal variation in 25(OH)D levels is evident among these patients. This study investigated older participants who were consecutively admitted between February 2015 and December 2016 to the geriatric acute care ward. Results of routine measurements of 25(OH)D at hospital admission were retrospectively analyzed and stratified according to months and seasons. Previous intake of vitamin D supplementation was derived from the patients' medical records. The study group comprised 679 participants (mean age 82.1±8.2; 457 females), of which 78% had vitamin D deficiency. Older individuals not taking vitamin D supplements had a lower mean serum 25(OH)D than those receiving supplements. Of those patients with no vitamin D supplementation, 87.0% were vitamin D deficient and only 5% showing sufficient vitamin 25(OH)D. Further, there were neither monthly nor seasonal variations in vitamin 25(OH)D levels among these patients and their vitamin D levels stayed far below the recommended threshold of 20 ng/ml across the seasons. Vitamin D deficiency was very prevalent in the subgroup of older hospitalized patients without vitamin D supplementation, irrespective of season. Since no seasonal variations in mean 25(OH)D levels was observed, sunlight dependent skin synthesis is unlikely to contribute to vitamin D status in these patients. Supplementation seems to be necessary to maintain desirable vitamin D levels among this population throughout the year.

  6. Polygons in Seasonal Frost

    Science.gov (United States)

    2004-01-01

    8 February 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a summertime scene in the south polar region of the red planet. A patch of bright frost--possibly water ice--is seen in the lower third of the image. Polygon patterns that have developed in the ice as it sublimes away can be seen; these are not evident in the defrosted surfaces, so they are thought to have formed in the frost. This image is located near 82.6oS, 352.5oW. Sunlight illuminates this scene from the upper left; the image covers an area 3 km (1.9 mi) wide.

  7. Seasonality in the Austrian Economy: Common Seasonals and Forecasting

    OpenAIRE

    Kunst, Robert M.

    1992-01-01

    Abstract: Seasonal cointegration generalizes the idea of cointegration to processes with unit roots at frequencies different from 0. Here, also the dual notion of common trends, "common seasonals", is adopted for the seasonal case. Using a five-variable macroeconomic core system of the Austrian economy, it is demonstrated how common seasonals and seasonal cointegrating vectors look in practice. Statistical tests provide clear evidence on seasonal cointegration in the system. However, it is sh...

  8. Seasonal Changes in the Character and Nitrogen Content of Dissolved Organic Matter in an Alpine/Subalpine Headwater Catchment

    Directory of Open Access Journals (Sweden)

    Eran W. Hood

    2001-01-01

    Full Text Available We are studying the chemical quality of dissolved organic nitrogen (DON in a high-elevation watershed in the Colorado Front Range. Samples were collected over the 2000 snowmelt runoff season at two sites across an alpine/subalpine ecotone to understand how the transition between the lightly vegetated alpine and forested reaches of the catchment influences the chemical character of DON. Samples were analyzed approximately weekly for dissolved organic material (DOM content and chemical character. A subset of samples was analyzed for the elemental content of fulvic and hydrophilic acids. Concentrations of DON at both sites were highest in the spring at the initiation of snowmelt, decreased during snowmelt, and increased again during the late summer and fall. In contrast, concentrations of dissolved organic carbon (DOC peaked on the ascending limb of the hydrograph and declined to seasonal minima on the descending limb of the hydrograph. The ratio of DOC:DON showed a seasonal shift at both sites with high values (40 to 55 during peak runoff in early summer and lower values (15 to 25 during low flows late in the runoff season. These results indicate that there was a seasonal change in the relative N content of DOM at both sites. Chemical fractionation of DOC showed that there were temporal and longitudinal changes in the chemical character of DOC. At the alpine site, the fulvic acid content of DOC decreased from 57% in June to 35% in September. The change in fulvic acid was less pronounced at the forested site, from 66% in June to 54% in September. Elemental analysis of fulvic and hydrophilic acids indicated that hydrophilic acids were N rich compared to fulvic acids. Additionally, fulvic and hydrophilic acids isolated at the alpine site had a lower C:N ratio than those isolated at the forested site. Similarly, the C:N ratio of organic acids at both sites was lower in September than in June during peak runoff. These differences appear to be a result

  9. Wind and sunlight shape microbial diversity in surface waters of the North Pacific Subtropical Gyre.

    Science.gov (United States)

    Bryant, Jessica A; Aylward, Frank O; Eppley, John M; Karl, David M; Church, Matthew J; DeLong, Edward F

    2016-06-01

    Few microbial time-series studies have been conducted in open ocean habitats having low seasonal variability such as the North Pacific Subtropical Gyre (NPSG), where surface waters experience comparatively mild seasonal variation. To better describe microbial seasonal variability in this habitat, we analyzed rRNA amplicon and shotgun metagenomic data over two years at the Hawaii Ocean Time-series Station ALOHA. We postulated that this relatively stable habitat might reveal different environmental factors that influence planktonic microbial community diversity than those previously observed in more seasonally dynamic habitats. Unexpectedly, the data showed that microbial diversity at 25 m was positively correlated with average wind speed 3 to 10 days prior to sampling. In addition, microbial community composition at 25 m exhibited significant correlations with solar irradiance. Many bacterial groups whose relative abundances varied with solar radiation corresponded to taxa known to exhibit strong seasonality in other oceanic regions. Network co-correlation analysis of 25 m communities showed seasonal transitions in composition, and distinct successional cohorts of co-occurring phylogenetic groups. Similar network analyses of metagenomic data also indicated distinct seasonality in genes originating from cyanophage, and several bacterial clades including SAR116 and SAR324. At 500 m, microbial community diversity and composition did not vary significantly with any measured environmental parameters. The minimal seasonal variability in the NPSG facilitated detection of more subtle environmental influences, such as episodic wind variation, on surface water microbial diversity. Community composition in NPSG surface waters varied in response to solar irradiance, but less dramatically than reported in other ocean provinces.

  10. Seasonality of Suicidal Behavior

    Science.gov (United States)

    Woo, Jong-Min; Okusaga, Olaoluwa; Postolache, Teodor T.

    2012-01-01

    A seasonal suicide peak in spring is highly replicated, but its specific cause is unknown. We reviewed the literature on suicide risk factors which can be associated with seasonal variation of suicide rates, assessing published articles from 1979 to 2011. Such risk factors include environmental determinants, including physical, chemical, and biological factors. We also summarized the influence of potential demographic and clinical characteristics such as age, gender, month of birth, socioeconomic status, methods of prior suicide attempt, and comorbid psychiatric and medical diseases. Comprehensive evaluation of risk factors which could be linked to the seasonal variation in suicide is important, not only to identify the major driving force for the seasonality of suicide, but also could lead to better suicide prevention in general. PMID:22470308

  11. Seasonal Affective Disorder

    Science.gov (United States)

    ... than any non-seasonal depressions. Symptoms of Major Depression Feeling depressed most of the day, nearly every ... Bethesda, MD 20892-9663 Follow Us Facebook Twitter YouTube Google Plus NIMH Newsletter NIMH RSS Feed NIMH ...

  12. CCAA seasonal forecasting

    International Development Research Centre (IDRC) Digital Library (Canada)

    Integrating meteorological and indigenous knowledge-based seasonal climate forecasts in ..... Explanation is based on spiritual and social values. Taught by .... that provided medicine and food became the subject of strict rules and practices ...

  13. 76 FR 62052 - Issuance of a Loan Guarantee to First Solar, Inc., for the Desert Sunlight Solar Farm Project

    Science.gov (United States)

    2011-10-06

    ... DEPARTMENT OF ENERGY Issuance of a Loan Guarantee to First Solar, Inc., for the Desert Sunlight Solar Farm Project AGENCY: U.S. Department of Energy. ACTION: Record of decision. SUMMARY: The U.S... The proposed DSSFP is a photovoltaic solar electrical generating facility using commercial, thin-film...

  14. Photodegradation of pharmaceuticals in the aquatic environment by sunlight and UV-A, -B and -C irradiation.

    Science.gov (United States)

    Kawabata, Kohei; Sugihara, Kazumi; Sanoh, Seigo; Kitamura, Shigeyuki; Ohta, Shigeru

    2013-01-01

    In order to investigate the effect of sunlight on the persistence and ecotoxicity of pharmaceuticals contaminating the aquatic environment, we exposed nine pharmaceuticals (acetaminophen (AA), amiodarone (AM), dapsone (DP), dexamethasone (DX), indomethacin (IM), naproxen (NP), phenytoin (PH), raloxifene (RL), and sulindac (SL)) in aqueous media to sunlight and to ultraviolet (UV) irradiation at 254, 302 or 365 nm (UV-C, UV-B or UV-A, respectively). Degradation of the pharmaceuticals was monitored by means of high-performance liquid chromatography (HPLC). Sunlight completely degraded AM, DP and DX within 6 hr, and partly degraded the other pharmaceuticals, except AA and PH, which were not degraded. Similar results were obtained with UV-B, while UV-A was less effective (both UV-A and -B are components of sunlight). All the pharmaceuticals were photodegraded by UV-C, which is used for sterilization in sewage treatment plants. Thus, the photodegradation rates of pharmaceuticals are dependent on both chemical structure and the wavelength of UV exposure. Toxicity assay using the luminescent bacteria test (ISO11348) indicated that UV irradiation reduced the toxicity of some pharmaceuticals to aquatic organisms by decreasing their amount (photodegradation) and increased the toxicity of others by generating toxic photoproduct(s). These results indicate the importance of investigating not only parent compounds, but also photoproducts in the risk assessment of pharmaceuticals in aquatic environments.

  15. Sunlight Induced Rapid Oil Absorption and Passive Room-Temperature Release: An Effective Solution toward Heavy Oil Spill Cleanup

    KAUST Repository

    Wu, Mengchun

    2018-05-18

    Rapid cleanup and easy recovery of spilled heavy oils is always a great challenge due to their high viscosity (>103 mPa s). One of the efficient methods to absorb highly viscous oils is to reduce their viscosity by increasing their temperature. In this work, the authors integrate the sunlight‐induced light‐to‐heat conversion effect of polypyrrole (PPy) and thermoresponsive property of poly(N‐isopropylacrylamide) (PNIPAm) into the melamine sponge, which successfully delivers a fast heavy oil absorption under sunlight and passive oil release underwater at room temperature. Thanks to the rationally designed functionalities, the PNIPAm/PPy functionalized sponges possess oleophilicity and hydrophobicity under sunlight. Due to the photothermal effect of PPy, the sponges locally heat up contacting heavy oil under sunlight and reduce its viscosity to a point where the oil voluntarily flow into the pores of the sponge. The material in this work is able to rapidly absorb the heavy oil with room temperature viscosity as high as ≈1.60 × 105 mPa s. The absorbed oil can be passively forced out the sponge underwater at room temperature due to the hydrophilicity of PNIPAm. The sunlight responsive and multifunctional sponge represents a meaningful attempt in coming up with a sustainable solution toward heavy oil spill.

  16. Fate of kelthane residues on apple pomace exposed to drying in the dark, sunlight, and ultraviolet light irradiation

    International Nuclear Information System (INIS)

    Archer, T.E.; Toscano, R.A.

    1972-01-01

    The present investigations were undertaken to determine the fate of Kelthane residues intentionally applied to apples under controlled laboratory conditions and the reduction of these residues in the pomace by exposure to drying in the dark, in sunlight, and ultraviolet light irradiation

  17. Use of sunlight to partially detoxify groundnut (peanut) cake flour and casein contaminated with aflatoxin B1.

    Science.gov (United States)

    Shantha, T; Murthy, V S

    1981-03-01

    Sunlight destroyed 83 and 50% of the toxin added to casein and groundnut cake flour, respectively. Equilibrium dialysis revealed that both casein and groundnut protein bind aflatoxin but the toxin bound to casein appeared more photo-labile than that bound to groundnut protein.

  18. 76 FR 50493 - Notice of Availability of the Record of Decision for the Desert Sunlight Holdings, LLC, Desert...

    Science.gov (United States)

    2011-08-15

    ... DEPARTMENT OF THE INTERIOR Bureau of Land Management [CACA-48649, LLCAD06000 L51010000 ER0000... right-of-way (ROW) application CACA-48649 for the Desert Sunlight Solar Farm Project (DSSF). The DSSF is... (CACA-052682) where the project would interconnect with the SCE regional transmission system. The DSSF...

  19. Sunlight Induced Rapid Oil Absorption and Passive Room-Temperature Release: An Effective Solution toward Heavy Oil Spill Cleanup

    KAUST Repository

    Wu, Mengchun; Shi, Yusuf; Chang, Jian; Li, Renyuan; Ong, Chi Siang; Wang, Peng

    2018-01-01

    Rapid cleanup and easy recovery of spilled heavy oils is always a great challenge due to their high viscosity (>103 mPa s). One of the efficient methods to absorb highly viscous oils is to reduce their viscosity by increasing their temperature. In this work, the authors integrate the sunlight‐induced light‐to‐heat conversion effect of polypyrrole (PPy) and thermoresponsive property of poly(N‐isopropylacrylamide) (PNIPAm) into the melamine sponge, which successfully delivers a fast heavy oil absorption under sunlight and passive oil release underwater at room temperature. Thanks to the rationally designed functionalities, the PNIPAm/PPy functionalized sponges possess oleophilicity and hydrophobicity under sunlight. Due to the photothermal effect of PPy, the sponges locally heat up contacting heavy oil under sunlight and reduce its viscosity to a point where the oil voluntarily flow into the pores of the sponge. The material in this work is able to rapidly absorb the heavy oil with room temperature viscosity as high as ≈1.60 × 105 mPa s. The absorbed oil can be passively forced out the sponge underwater at room temperature due to the hydrophilicity of PNIPAm. The sunlight responsive and multifunctional sponge represents a meaningful attempt in coming up with a sustainable solution toward heavy oil spill.

  20. Decoding the drivers of bank erosion on the Mekong river: The roles of the Asian monsoon, tropical storms, and snowmelt.

    Science.gov (United States)

    Darby, Stephen E; Leyland, Julian; Kummu, Matti; Räsänen, Timo A; Lauri, Hannu

    2013-04-01

    We evaluate links between climate and simulated river bank erosion for one of the world's largest rivers, the Mekong. We employ a process-based model to reconstruct multidecadal time series of bank erosion at study sites within the Mekong's two main hydrological response zones, defining a new parameter, accumulated excess runoff (AER), pertinent to bank erosion. We employ a hydrological model to isolate how snowmelt, tropical storms and monsoon precipitation each contribute to AER and thus modeled bank erosion. Our results show that melt (23.9% at the upstream study site, declining to 11.1% downstream) and tropical cyclones (17.5% and 26.4% at the upstream and downstream sites, respectively) both force significant fractions of bank erosion on the Mekong. We also show (i) small, but significant, declines in AER and hence assumed bank erosion during the 20th century, and; (ii) that significant correlations exist between AER and the Indian Ocean Dipole (IOD) and El Niño Southern Oscillation (ENSO). Of these modes of climate variability, we find that IOD events exert a greater control on simulated bank erosion than ENSO events; but the influences of both ENSO and IOD when averaged over several decades are found to be relatively weak. However, importantly, relationships between ENSO, IOD, and AER and hence inferred river bank erosion are not time invariant. Specifically, we show that there is an intense and prolonged epoch of strong coherence between ENSO and AER from the early 1980s to present, such that in recent decades derived Mekong River bank erosion has been more strongly affected by ENSO.

  1. Numerical simulation of extreme snowmelt observed at the SIGMA-A site, northwest Greenland, during summer 2012

    Directory of Open Access Journals (Sweden)

    M. Niwano

    2015-05-01

    Full Text Available The surface energy balance (SEB from 30 June to 14 July 2012 at site SIGMA (Snow Impurity and Glacial Microbe effects on abrupt warming in the Arctic-A, (78°03' N, 67°38' W; 1490 m a.s.l. on the northwest Greenland Ice Sheet (GrIS was investigated by using in situ atmospheric and snow measurements as well as numerical modeling with a one-dimensional multi-layered physical snowpack model called SMAP (Snow Metamorphism and Albedo Process. At SIGMA-A, remarkable near-surface snowmelt and continuous heavy rainfall (accumulated precipitation between 10 and 14 July was estimated to be 100 mm were observed after 10 July 2012. Application of the SMAP model to the GrIS snowpack was evaluated based on the snow temperature profile, snow surface temperature, surface snow grain size, and shortwave albedo, all of which the model simulated reasonably well. Above all, the fact that the SMAP model successfully reproduced frequently observed rapid increases in snow albedo under cloudy conditions highlights the advantage of the physically based snow albedo model (PBSAM incorporated in the SMAP model. Using such data and model, we estimated the SEB at SIGMA-A from 30 June to 14 July 2012. Radiation-related fluxes were obtained from in situ measurements, whereas other fluxes were calculated with the SMAP model. By examining the components of the SEB, we determined that low-level clouds accompanied by a significant temperature increase played an important role in the melt event observed at SIGMA-A. These conditions induced a remarkable surface heating via cloud radiative forcing in the polar region.

  2. Using Temperature Forecasts to Improve Seasonal Streamflow Forecasts in the Colorado and Rio Grande Basins

    Science.gov (United States)

    Lehner, F.; Wood, A.; Llewellyn, D.; Blatchford, D. B.; Goodbody, A. G.; Pappenberger, F.

    2017-12-01

    Recent studies have documented the influence of increasing temperature on streamflow across the American West, including snow-melt driven rivers such as the Colorado or Rio Grande. At the same time, some basins are reporting decreasing skill in seasonal streamflow forecasts, termed water supply forecasts (WSFs), over the recent decade. While the skill in seasonal precipitation forecasts from dynamical models remains low, their skill in predicting seasonal temperature variations could potentially be harvested for WSFs to account for non-stationarity in regional temperatures. Here, we investigate whether WSF skill can be improved by incorporating seasonal temperature forecasts from dynamical forecasting models (from the North American Multi Model Ensemble and the European Centre for Medium-Range Weather Forecast System 4) into traditional statistical forecast models. We find improved streamflow forecast skill relative to traditional WSF approaches in a majority of headwater locations in the Colorado and Rio Grande basins. Incorporation of temperature into WSFs thus provides a promising avenue to increase the robustness of current forecasting techniques in the face of continued regional warming.

  3. Similar photoperiod-related birth seasonalities among professional baseball players and lesbian women with an opposite seasonality among gay men: Maternal melatonin may affect fetal sexual dimorphism.

    Science.gov (United States)

    Marzullo, Giovanni

    2014-05-30

    Based on pre-mid-20th-century data, the same photoperiod-related birth seasonality previously observed in schizophrenia was also recently found in neural-tube defects and in extreme left-handedness among professional baseball players. This led to a hypothesis implicating maternal melatonin and other mediators of sunlight actions capable of affecting 4th-embryonic-week developments including neural-tube closure and left-right differentiation of the brain. Here, new studies of baseball players suggest that the same sunlight actions could also affect testosterone-dependent male-female differentiation in the 4-month-old fetus. Independently of hand-preferences, baseball players (n=6829), and particularly the stronger hitters among them, showed a unique birth seasonality with an excess around early-November and an equally significant deficit 6 months later around early-May. In two smaller studies, north-American and other northern-hemisphere born lesbians showed the same strong-hitter birth seasonality while gay men showed the opposite seasonality. The sexual dimorphism-critical 4th-fetal-month testosterone surge coincides with the summer-solstice in early-November births and the winter-solstice in early-May births. These coincidences are discussed and a "melatonin mechanism" is proposed based on evidence that in seasonal breeders maternal melatonin imparts "photoperiodic history" to the newborn by direct inhibition of fetal testicular testosterone synthesis. The present effects could represent a vestige of this same phenomenon in man. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  4. Diffused sunlight driven highly synergistic pathway for complete mineralization of organic contaminants using reduced graphene oxide supported photocatalyst

    Energy Technology Data Exchange (ETDEWEB)

    Babu, Sundaram Ganesh; Ramalingam Vinoth [SRM Research Institute, SRM University, Kattankulathur 603203, Chennai, Tamilnadu (India); Neppolian, Bernaurdshaw, E-mail: neppolian.b@res.srmuniv.ac.in [SRM Research Institute, SRM University, Kattankulathur 603203, Chennai, Tamilnadu (India); Dionysiou, Dionysios D. [Environmental Engineering and Science Program, Department of Biomedical, Chemical and Environmental Engineering, University of Cincinnati, Cincinnati, OH 45221-0012 (United States); Ashokkumar, Muthupandian [The School of Chemistry, University of Melbourne, Parkville, Melbourne, Victoria 3010 (Australia)

    2015-06-30

    Highlights: • Diffused sunlight is firstly used as an effective source for the degradation of organics. • More than 10 fold synergistic effect is achieved by sono-photocatalysis. • rGO enhances the degradation efficiency up to 54% as compared with CuO–TiO{sub 2} alone. • Plausible mechanism and intermediates formed are supported with experimental studies. - Abstract: Diffused sunlight is found to be an effective light source for the efficient degradation and mineralization of organic pollutant (methyl orange as a probe) by sono-photocatalytic degradation using reduced graphene oxide (rGO) supported CuO–TiO{sub 2} photocatalyst. The prepared catalysts are characterized by XRD, XPS, UV–vis DRS, PL, photoelectrochemical, SEM-EDS and TEM. A 10 fold synergy is achieved for the first time by combining sonochemical and photocatalytic degradation under diffused sunlight. rGO loading augments the activity of bare CuO–TiO{sub 2} more than two fold. The ability of rGO in storing, transferring, and shuttling electrons at the heterojunction between TiO{sub 2} and CuO facilitates the separation of photogenerated electron–hole pairs, as evidenced by the photoluminescence results. The complete mineralization of MO and the by-products within a short span of time is confirmed by TOC analysis. Further, hydroxyl radical mediated degradation under diffused sunlight is confirmed by LC–MS. This system shows similar activity for the degradation of methylene blue and 4-chlorophenol indicating the versatility of the catalyst for the degradation of various pollutants. This investigation is likely to open new possibilities for the development of highly efficient diffused sunlight driven TiO{sub 2} based photocatalysts for the complete mineralization of organic contaminants.

  5. Sunlight exposure is important for preventing hip fractures in patients with Alzheimer's disease, Parkinson's disease, or stroke.

    Science.gov (United States)

    Iwamoto, J; Takeda, T; Matsumoto, H

    2012-04-01

    Hypovitaminosis D as a result of malnutrition or sunlight deprivation, increased bone resorption, low bone mineral density (BMD), or an increased risk of falls may contribute to an increased risk of hip fractures in patients with neurological diseases, including Alzheimer's disease, Parkinson's disease, and stroke. The purpose of this study was to clarify the efficacy of sunlight exposure for reducing the risk of hip fractures in patients with such neurological diseases. The English literature was searched using PubMed, and randomized controlled trials evaluating the efficacy of sunlight exposure for reducing the risk of hip fractures in patients with Alzheimer's disease, Parkinson's disease, and stroke were identified. The relative risk and the 95% confidence interval were calculated for individual randomized controlled trials, and a pooled data analysis (meta-analysis) was performed. Three randomized controlled trials were identified. Sunlight exposure improved hypovitaminosis D and increased the BMD. The relative risk (95% confidence interval) of hip fractures was 0.22 (0.05, 1.01) for Alzheimer's disease, 0.27 (0.08, 0.96) for Parkinson's disease, and 0.17 (0.02, 1.36) for stroke. The relative risk (95% confidence interval) calculated for the pooled data analysis was 0.23 (0.10, 0.56) (P = 0.0012), suggesting a significant risk reduction rate of 77%. The present meta-analysis added additional evidence indicating the efficacy of sunlight exposure for reducing the risk of hip fractures in patients with Alzheimer's disease, Parkinson's disease, and stroke. © 2011 John Wiley & Sons A/S.

  6. Amazon Forests Maintain Consistent Canopy Structure and Greenness During the Dry Season

    Science.gov (United States)

    Morton, Douglas C.; Nagol, Jyoteshwar; Carabajal, Claudia C.; Rosette, Jacqueline; Palace, Michael; Cook, Bruce D.; Vermote, Eric F.; Harding, David J.; North, Peter R. J.

    2014-01-01

    The seasonality of sunlight and rainfall regulates net primary production in tropical forests. Previous studies have suggested that light is more limiting than water for tropical forest productivity, consistent with greening of Amazon forests during the dry season in satellite data.We evaluated four potential mechanisms for the seasonal green-up phenomenon, including increases in leaf area or leaf reflectance, using a sophisticated radiative transfer model and independent satellite observations from lidar and optical sensors. Here we show that the apparent green up of Amazon forests in optical remote sensing data resulted from seasonal changes in near-infrared reflectance, an artefact of variations in sun-sensor geometry. Correcting this bidirectional reflectance effect eliminated seasonal changes in surface reflectance, consistent with independent lidar observations and model simulations with unchanging canopy properties. The stability of Amazon forest structure and reflectance over seasonal timescales challenges the paradigm of light-limited net primary production in Amazon forests and enhanced forest growth during drought conditions. Correcting optical remote sensing data for artefacts of sun-sensor geometry is essential to isolate the response of global vegetation to seasonal and interannual climate variability.

  7. Seasonal variability of the hydrogen exosphere of Mars

    Science.gov (United States)

    Halekas, J. S.

    2017-05-01

    The Mars Atmosphere and Volatile EvolutioN (MAVEN) mission measures both the upstream solar wind and collisional products from energetic neutral hydrogen atoms that precipitate into the upper atmosphere after their initial formation by charge exchange with exospheric hydrogen. By computing the ratio between the densities of these populations, we derive a robust measurement of the column density of exospheric hydrogen upstream of the Martian bow shock. By comparing with Chamberlain-type model exospheres, we place new constraints on the structure and escape rates of exospheric hydrogen, derived from observations sensitive to a different and potentially complementary column from most scattered sunlight observations. Our observations provide quantitative estimates of the hydrogen exosphere with nearly complete temporal coverage, revealing order of magnitude seasonal changes in column density and a peak slightly after perihelion, approximately at southern summer solstice. The timing of this peak suggests either a lag in the response of the Martian atmosphere to solar inputs or a seasonal effect driven by lower atmosphere dynamics. The high degree of seasonal variability implied by our observations suggests that the Martian atmosphere and the thermal escape of light elements depend sensitively on solar inputs.

  8. Nocturnal light pollution and underexposure to daytime sunlight: Complementary mechanisms of circadian disruption and related diseases.

    Science.gov (United States)

    Smolensky, Michael H; Sackett-Lundeen, Linda L; Portaluppi, Francesco

    2015-01-01

    Routine exposure to artificial light at night (ALAN) in work, home, and community settings is linked with increased risk of breast and prostate cancer (BC, PC) in normally sighted women and men, the hypothesized biological rhythm mechanisms being frequent nocturnal melatonin synthesis suppression, circadian time structure (CTS) desynchronization, and sleep/wake cycle disruption with sleep deprivation. ALAN-induced perturbation of the CTS melatonin synchronizer signal is communicated maternally at the very onset of life and after birth via breast or artificial formula feedings. Nighttime use of personal computers, mobile phones, electronic tablets, televisions, and the like--now epidemic in adolescents and adults and highly prevalent in pre-school and school-aged children--is a new source of ALAN. However, ALAN exposure occurs concomitantly with almost complete absence of daytime sunlight, whose blue-violet (446-484 nm λ) spectrum synchronizes the CTS and whose UV-B (290-315 nm λ) spectrum stimulates vitamin D synthesis. Under natural conditions and clear skies, day/night and annual cycles of UV-B irradiation drive corresponding periodicities in vitamin D synthesis and numerous bioprocesses regulated by active metabolites augment and strengthen the biological time structure. Vitamin D insufficiency and deficiency are widespread in children and adults in developed and developing countries as a consequence of inadequate sunlight exposure. Past epidemiologic studies have focused either on exposure to too little daytime UV-B or too much ALAN, respectively, on vitamin D deficiency/insufficiency or melatonin suppression in relation to risk of cancer and other, e.g., psychiatric, hypertensive, cardiac, and vascular, so-called, diseases of civilization. The observed elevated incidence of medical conditions the two are alleged to influence through many complementary bioprocesses of cells, tissues, and organs led us to examine effects of the totality of the artificial light

  9. Sunlight-exposed biofilm microbial communities are naturally resistant to chernobyl ionizing-radiation levels.

    Directory of Open Access Journals (Sweden)

    Marie Ragon

    Full Text Available BACKGROUND: The Chernobyl accident represents a long-term experiment on the effects of exposure to ionizing radiation at the ecosystem level. Though studies of these effects on plants and animals are abundant, the study of how Chernobyl radiation levels affect prokaryotic and eukaryotic microbial communities is practically non-existent, except for a few reports on human pathogens or soil microorganisms. Environments enduring extreme desiccation and UV radiation, such as sunlight exposed biofilms could in principle select for organisms highly resistant to ionizing radiation as well. METHODOLOGY/PRINCIPAL FINDINGS: To test this hypothesis, we explored the diversity of microorganisms belonging to the three domains of life by cultivation-independent approaches in biofilms developing on concrete walls or pillars in the Chernobyl area exposed to different levels of radiation, and we compared them with a similar biofilm from a non-irradiated site in Northern Ireland. Actinobacteria, Alphaproteobacteria, Bacteroidetes, Acidobacteria and Deinococcales were the most consistently detected bacterial groups, whereas green algae (Chlorophyta and ascomycete fungi (Ascomycota dominated within the eukaryotes. Close relatives to the most radio-resistant organisms known, including Rubrobacter species, Deinococcales and melanized ascomycete fungi were always detected. The diversity of bacteria and eukaryotes found in the most highly irradiated samples was comparable to that of less irradiated Chernobyl sites and Northern Ireland. However, the study of mutation frequencies in non-coding ITS regions versus SSU rRNA genes in members of a same actinobacterial operational taxonomic unit (OTU present in Chernobyl samples and Northern Ireland showed a positive correlation between increased radiation and mutation rates. CONCLUSIONS/SIGNIFICANCE: Our results show that biofilm microbial communities in the most irradiated samples are comparable to non-irradiated samples in

  10. Sunlight-Exposed Biofilm Microbial Communities Are Naturally Resistant to Chernobyl Ionizing-Radiation Levels

    Science.gov (United States)

    Ragon, Marie; Restoux, Gwendal; Moreira, David; Møller, Anders Pape; López-García, Purificación

    2011-01-01

    Background The Chernobyl accident represents a long-term experiment on the effects of exposure to ionizing radiation at the ecosystem level. Though studies of these effects on plants and animals are abundant, the study of how Chernobyl radiation levels affect prokaryotic and eukaryotic microbial communities is practically non-existent, except for a few reports on human pathogens or soil microorganisms. Environments enduring extreme desiccation and UV radiation, such as sunlight exposed biofilms could in principle select for organisms highly resistant to ionizing radiation as well. Methodology/Principal Findings To test this hypothesis, we explored the diversity of microorganisms belonging to the three domains of life by cultivation-independent approaches in biofilms developing on concrete walls or pillars in the Chernobyl area exposed to different levels of radiation, and we compared them with a similar biofilm from a non-irradiated site in Northern Ireland. Actinobacteria, Alphaproteobacteria, Bacteroidetes, Acidobacteria and Deinococcales were the most consistently detected bacterial groups, whereas green algae (Chlorophyta) and ascomycete fungi (Ascomycota) dominated within the eukaryotes. Close relatives to the most radio-resistant organisms known, including Rubrobacter species, Deinococcales and melanized ascomycete fungi were always detected. The diversity of bacteria and eukaryotes found in the most highly irradiated samples was comparable to that of less irradiated Chernobyl sites and Northern Ireland. However, the study of mutation frequencies in non-coding ITS regions versus SSU rRNA genes in members of a same actinobacterial operational taxonomic unit (OTU) present in Chernobyl samples and Northern Ireland showed a positive correlation between increased radiation and mutation rates. Conclusions/Significance Our results show that biofilm microbial communities in the most irradiated samples are comparable to non-irradiated samples in terms of general

  11. Application of a UV-Vis submersible probe for capturing changes in DOC concentrations across a mire complex during the snowmelt and summer periods

    Science.gov (United States)

    Avagyan, Armine; Runkle, Benjamin; Kutzbach, Lars

    2013-04-01

    An accurate quantification of dissolved organic carbon (DOC) is crucial for understanding changes in water resources under the influence of climate, land use and urbanization. However, the conventionally used methods do not allow high frequency in situ analyses in remote or hostile environments (e.g., industrial wastewater or during environmental high-flow events, such as snowmelt or floods). In particular, missing measurements during the snowmelt period in landscapes of the boreal region can lead to significant miscalculations in regional carbon budgets. Therefore, the aim of the study was to test the performance of a portable, submersible UV-Vis spectrophotometer (spectro::lyser, s::can Messtechnik GmbH, Austria) during the snowmelt period in a boreal mire-forest catchment, and to provide a conceptual understanding of the spatial and temporal dynamics of DOC concentrations during and after snowmelt. During 2011, water samples were collected from the near-pristine Ust-Pojeg mire complex in northwestern Russia (61° 56'N, 50° 13'E). Sampling started during the spring snowmelt period and continued until late fall. The mire presented a mosaic of different landscape units. The mire consisted of minerogeous (fen), ombrogenous (bog), and transitional forest-mire (lagg) zones. Water samples were taken from the surface across the mire (22 points at 50-m intervals). DOC concentrations were analyzed directly at the study site using a portable, submersible UV-Vis spectrophotometer, which uses high-resolution absorbance measurements over the wavelength range 200-742.5 nm at 2.5-nm intervals as a proxy for DOC content. Because the DOC composition of fluids varies by site, a local calibration replaced the default settings of the spectro::lyser (Global Calibration) to enhance the accuracy of the measurements. To evaluate the local calibration and correct for drift, the same samples (n = 157) were additionally analyzed using the wet persulfate oxidation method (O

  12. Inverse Geochemical Reaction Path Modelling and the Impact of Climate Change on Hydrologic Structure in Snowmelt-Dominated Catchments in the Southwestern USA

    Science.gov (United States)

    Driscoll, J. M.; Meixner, T.; Molotch, N. P.; Sickman, J. O.; Williams, M. W.; McIntosh, J. C.; Brooks, P. D.

    2011-12-01

    Snowmelt from alpine catchments provides 70-80% of the American Southwest's water resources. Climate change threatens to alter the timing and duration of snowmelt in high elevation catchments, which may also impact the quantity and the quality of these water resources. Modelling of these systems provides a robust theoretical framework to process the information extracted from the sparse physical measurement available in these sites due to their remote locations. Mass-balance inverse geochemical models (via PHREEQC, developed by the USGS) were applied to two snowmelt-dominated catchments; Green Lake 4 (GL4) in the Rockies and Emerald Lake (EMD) in the Sierra Nevada. Both catchments primarily consist of granite and granodiorite with a similar bulk geochemistry. The inputs for the models were the initial (snowpack) and final (catchment output) hydrochemistry and a catchment-specific suite of mineral weathering reactions. Models were run for wet and dry snow years, for early and late time periods (defined hydrologically as 1/2 of the total volume for the year). Multiple model solutions were reduced to a representative suite of reactions by choosing the model solution with the fewest phases and least overall phase change. The dominant weathering reactions (those which contributed the most solutes) were plagioclase for GL4 and albite for EMD. Results for GL4 show overall more plagioclase weathering during the dry year (214.2g) than wet year (89.9g). Both wet and dry years show more weathering in the early time periods (63% and 56%, respectively). These results show that the snowpack and outlet are chemically more similar during wet years than dry years. A possible hypothesis to explain this difference is a change in contribution from subsurface storage; during the wet year the saturated catchment reduces contact with surface materials that would result in mineral weathering reactions by some combination of reduced infiltration and decreased subsurface transit time. By

  13. Evaluation and Application of Gridded Snow Water Equivalent Products for Improving Snowmelt Flood Predictions in the Red River Basin of the North

    Science.gov (United States)

    Schroeder, R.; Jacobs, J. M.; Vuyovich, C.; Cho, E.; Tuttle, S. E.

    2017-12-01

    Each spring the Red River basin (RRB) of the North, located between the states of Minnesota and North Dakota and southern Manitoba, is vulnerable to dangerous spring snowmelt floods. Flat terrain, low permeability soils and a lack of satisfactory ground observations of snow pack conditions make accurate predictions of the onset and magnitude of major spring flood events in the RRB very challenging. This study investigated the potential benefit of using gridded snow water equivalent (SWE) products from passive microwave satellite missions and model output simulations to improve snowmelt flood predictions in the RRB using NOAA's operational Community Hydrologic Prediction System (CHPS). Level-3 satellite SWE products from AMSR-E, AMSR2 and SSM/I, as well as SWE computed from Level-2 brightness temperatures (Tb) measurements, including model output simulations of SWE from SNODAS and GlobSnow-2 were chosen to support the snowmelt modeling exercises. SWE observations were aggregated spatially (i.e. to the NOAA North Central River Forecast Center forecast basins) and temporally (i.e. by obtaining daily screened and weekly unscreened maximum SWE composites) to assess the value of daily satellite SWE observations relative to weekly maximums. Data screening methods removed the impacts of snow melt and cloud contamination on SWE and consisted of diurnal SWE differences and a temperature-insensitive polarization difference ratio, respectively. We examined the ability of the satellite and model output simulations to capture peak SWE and investigated temporal accuracies of screened and unscreened satellite and model output SWE. The resulting SWE observations were employed to update the SNOW-17 snow accumulation and ablation model of CHPS to assess the benefit of using temporally and spatially consistent SWE observations for snow melt predictions in two test basins in the RRB.

  14. Standard Test Method for Electrical Performance of Concentrator Terrestrial Photovoltaic Modules and Systems Under Natural Sunlight

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2009-01-01

    1.1 This test method covers the determination of the electrical performance of photovoltaic concentrator modules and systems under natural sunlight using a normal incidence pyrheliometer. 1.2 The test method is limited to module assemblies and systems where the geometric concentration ratio specified by the manufacturer is greater than 5. 1.3 This test method applies to concentrators that use passive cooling where the cell temperature is related to the air temperature. 1.4 Measurements under a variety of conditions are allowed; results are reported under a select set of concentrator reporting conditions to facilitate comparison of results. 1.5 This test method applies only to concentrator terrestrial modules and systems. 1.6 This test method assumes that the module or system electrical performance characteristics do not change during the period of test. 1.7 The performance rating determined by this test method applies only at the period of the test, and implies no past or future performance level. 1.8...

  15. Standard Test Method for Electrical Performance of Photovoltaic Cells Using Reference Cells Under Simulated Sunlight

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2009-01-01

    1.1 This test method covers the determination of the electrical performance of a photovoltaic cell under simulated sunlight by means of a calibrated reference cell procedure. 1.2 Electrical performance measurements are reported with respect to a select set of standard reporting conditions (SRC) (see Table 1) or to user-specified conditions. 1.2.1 The SRC or user-specified conditions include the cell temperature, the total irradiance, and the reference spectral irradiance distribution. 1.3 This test method is applicable only to photovoltaic cells with a linear response over the range of interest. 1.4 The cell parameters determined by this test method apply only at the time of test, and imply no past or future performance level. 1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this s...

  16. Genotoxic action of sunlight upon Bacillus subtilis spores: monitoring studies at Tokyo, Japan.

    Science.gov (United States)

    Munakata, N

    1989-12-01

    Samples of Bacillus subtilis spores dried on membrane filter were exposed to natural sunlight from solar-noon time at Tokyo. The survival and mutation induction of wild-type (UVR) and repair-deficient (UVS) spores were determined on 66 occasions since 1979. Two of the values were considered to be useful in monitoring solar UV intensity; the inverse of the time (in minutes) of exposure to kill 63% of the UVS spores ("sporocidal index") and the induced mutation frequency at 60 minutes of exposure of the UVR spores ("mutagenic index"). Both values were varied greatly due to time of a year, weather and other conditions. Estimates of year-round changes under clear skies were obtained by connecting the maximum values attained in these years. In these curves, there are more than 7-fold differences in the genotoxicity between winter and summer months, with major increases observed in early spring and decreases through autumn. Using a series of UV cut-off filters, the wavelengths most effective for the sporocidal actions were estimated to be in the range of 308-325 nm, shorter wavelengths being effective when the genotoxicity was higher. Sunburn meter of Robertson-Berger type seems to respond to slightly longer wavelength components of the solar spectrum. However, a reasonable correlation was obtained between the reading of the meter and the sporocidal index.

  17. Mycorrhiza symbiosis increases the surface for sunlight capture in Medicago truncatula for better photosynthetic production.

    Directory of Open Access Journals (Sweden)

    Lisa Adolfsson

    Full Text Available Arbuscular mycorrhizal (AM fungi play a prominent role in plant nutrition by supplying mineral nutrients, particularly inorganic phosphate (Pi, and also constitute an important carbon sink. AM stimulates plant growth and development, but the underlying mechanisms are not well understood. In this study, Medicago truncatula plants were grown with Rhizophagus irregularis BEG141 inoculum (AM, mock inoculum (control or with P(i fertilization. We hypothesized that AM stimulates plant growth through either modifications of leaf anatomy or photosynthetic activity per leaf area. We investigated whether these effects are shared with P(i fertilization, and also assessed the relationship between levels of AM colonization and these effects. We found that increased P(i supply by either mycorrhization or fertilization led to improved shoot growth associated with increased nitrogen uptake and carbon assimilation. Both mycorrhized and P(i-fertilized plants had more and longer branches with larger and thicker leaves than the control plants, resulting in an increased photosynthetically active area. AM-specific effects were earlier appearance of the first growth axes and increased number of chloroplasts per cell section, since they were not induced by P(i fertilization. Photosynthetic activity per leaf area remained the same regardless of type of treatment. In conclusion, the increase in growth of mycorrhized and P(i-fertilized Medicago truncatula plants is linked to an increase in the surface for sunlight capture, hence increasing their photosynthetic production, rather than to an increase in the photosynthetic activity per leaf area.

  18. Direct photolysis rates and transformation pathways of the lampricides TFM and niclosamide in simulated sunlight

    Science.gov (United States)

    McConville, Megan B.; Hubert, Terrance D.; Remucal, Christina K.

    2016-01-01

    The lampricides 3-trifluoromethyl-4-nitrophenol (TFM) and 2′,5-dichloro-4′-nitrosalicylanilide (niclosamide) are directly added to many tributaries of the Great Lakes that harbor the invasive parasitic sea lamprey. Despite their long history of use, the fate of lampricides is not well understood. This study evaluates the rate and pathway of direct photodegradation of both lampricides under simulated sunlight. The estimated half-lives of TFM range from 16.6 ± 0.2 h (pH 9) to 32.9 ± 1.0 h (pH 6), while the half-lives of niclosamide range from 8.88 ± 0.52 days (pH 6) to 382 ± 83 days (pH 9) assuming continuous irradiation over a water depth of 55 cm. Both compounds degrade to form a series of aromatic intermediates, simple organic acids, ring cleavage products, and inorganic ions. Experimental data were used to construct a kinetic model which demonstrates that the aromatic products of TFM undergo rapid photolysis and emphasizes that niclosamide degradation is the rate-limiting step to dehalogenation and mineralization of the lampricide. This study demonstrates that TFM photodegradation is likely to occur on the time scale of lampricide applications (2–5 days), while niclosamide, the less selective lampricide, will undergo minimal direct photodegradation during its passage to the Great Lakes.

  19. Vitamin D, cod-liver oil, sunlight, and rickets: a historical perspective.

    Science.gov (United States)

    Rajakumar, Kumaravel

    2003-08-01

    Rickets, a disease of vitamin D deficiency, is rarely confronted by the practicing pediatrician in the United States today. At the turn of the 20th century, rickets was rampant among the poor children living in the industrialized and polluted northern cities of the United States. With the discovery of vitamin D and the delineation of the anti-rachitic properties of cod-liver oil by the 1930s, it became possible to not only treat but also eradicate rickets in the United States. Rickets was a common disease in 17th century England. Frances Glisson's treatise on rickets published in 1650, a glorious contribution to English medicine, described the clinical and anatomic features of rickets in great detail. The exact etiology of rickets had been elusive until the 1920s. During the Glissonian era, rickets was a mysterious disease. By the late 19th and early 20th century, faulty diet or faulty environment (poor hygiene, lack of fresh air and sunshine) or lack of exercise was implicated in its etiology. Animal experiments, appreciation of folklore advocating the benefits of cod-liver oil, and the geographical association of rickets to lack of sunshine were all relevant factors in the advancement of knowledge in the conquest of this malady. In this article, the history of rickets pertaining to the discovery of vitamin D, cod-liver oil, and sunlight is reviewed.

  20. Towards a Better Understanding of the Molecular Mechanisms Involved in Sunlight-Induced Melanoma

    Directory of Open Access Journals (Sweden)

    Williams Mandy

    2005-01-01

    Full Text Available Although much less prevalent than its nonmelanoma skin cancer counterparts, cutaneous malignant melanoma (CMM is the most lethal human skin cancer. Epidemiological and biological studies have established a strong link between lifetime exposure to ultraviolet (UV light, particularly sunburn in childhood, and the development of melanoma. However, the specific molecular targets of this environmental carcinogen are not known. Data obtained from genetic and molecular studies over the last few years have identified the INK4a/ARF locus as the “gatekeeper” melanoma suppressor, encoding two tumour suppressor proteins in human, p16 INK4a and p14 ARF . Recent developments in molecular biotechnology and research using laboratory animals have made a significant gene breakthrough identifying the components of the p16 INK4a /Rb pathway as the principal and rate-limiting targets of UV radiation actions in melanoma formation. This review summarizes the current knowledge of the molecular mechanisms involved in melanoma development and its relationship to sunlight UV radiation.

  1. Spectropolarimetric Measurements of Scattered Sunlight in the Huggins Bands: Retrieval of Tropospheric Ozone Profiles

    Science.gov (United States)

    Fu, D.; Sander, S. P.; Stutz, J.; Pongetti, T. J.; Yung, Y. L.; Wong, M.; Natraj, V.; Li, K.; Shia, R.

    2009-12-01

    Ozone concentrations in the troposphere have increased over the past century as a result of anthropogenic emissions of NOx and volatile organic compounds. In addition to being harmful to human health and plant life, ozone is an important greenhouse gas, especially in the middle and upper troposphere. Therefore, accurate monitoring of tropospheric ozone vertical distributions is crucial for a better understanding of air quality and climate change. Simulations of vector radiative transfer in the near ultraviolet region have shown that tropospheric ozone profiles can be retrieved using polarization measurements. However, to date there has been no experimental test of this method. A new compact, portable spectropolarimeter has been built for atmospheric remote sensing. The first comprehensive description of the configuration and performance of this instrument for ground-based operation is provided and sample atmospheric scattered sunlight spectra are shown. Using optimal estimation retrieval theory we study the information content of polarization spectra in the Huggins band and uncertainties in the retrieval associated with the measurement parameters, such as aerosol scattering.

  2. Mycorrhiza Symbiosis Increases the Surface for Sunlight Capture in Medicago truncatula for Better Photosynthetic Production

    Science.gov (United States)

    Adolfsson, Lisa; Keresztes, Áron; Uddling, Johan; Schoefs, Benoît; Spetea, Cornelia

    2015-01-01

    Arbuscular mycorrhizal (AM) fungi play a prominent role in plant nutrition by supplying mineral nutrients, particularly inorganic phosphate (Pi), and also constitute an important carbon sink. AM stimulates plant growth and development, but the underlying mechanisms are not well understood. In this study, Medicago truncatula plants were grown with Rhizophagus irregularis BEG141 inoculum (AM), mock inoculum (control) or with Pi fertilization. We hypothesized that AM stimulates plant growth through either modifications of leaf anatomy or photosynthetic activity per leaf area. We investigated whether these effects are shared with Pi fertilization, and also assessed the relationship between levels of AM colonization and these effects. We found that increased Pi supply by either mycorrhization or fertilization led to improved shoot growth associated with increased nitrogen uptake and carbon assimilation. Both mycorrhized and Pi-fertilized plants had more and longer branches with larger and thicker leaves than the control plants, resulting in an increased photosynthetically active area. AM-specific effects were earlier appearance of the first growth axes and increased number of chloroplasts per cell section, since they were not induced by Pi fertilization. Photosynthetic activity per leaf area remained the same regardless of type of treatment. In conclusion, the increase in growth of mycorrhized and Pi-fertilized Medicago truncatula plants is linked to an increase in the surface for sunlight capture, hence increasing their photosynthetic production, rather than to an increase in the photosynthetic activity per leaf area. PMID:25615871

  3. Direct Photolysis Rates and Transformation Pathways of the Lampricides TFM and Niclosamide in Simulated Sunlight.

    Science.gov (United States)

    McConville, Megan B; Hubert, Terrance D; Remucal, Christina K

    2016-09-20

    The lampricides 3-trifluoromethyl-4-nitrophenol (TFM) and 2',5-dichloro-4'-nitrosalicylanilide (niclosamide) are directly added to many tributaries of the Great Lakes that harbor the invasive parasitic sea lamprey. Despite their long history of use, the fate of lampricides is not well understood. This study evaluates the rate and pathway of direct photodegradation of both lampricides under simulated sunlight. The estimated half-lives of TFM range from 16.6 ± 0.2 h (pH 9) to 32.9 ± 1.0 h (pH 6), while the half-lives of niclosamide range from 8.88 ± 0.52 days (pH 6) to 382 ± 83 days (pH 9) assuming continuous irradiation over a water depth of 55 cm. Both compounds degrade to form a series of aromatic intermediates, simple organic acids, ring cleavage products, and inorganic ions. Experimental data were used to construct a kinetic model which demonstrates that the aromatic products of TFM undergo rapid photolysis and emphasizes that niclosamide degradation is the rate-limiting step to dehalogenation and mineralization of the lampricide. This study demonstrates that TFM photodegradation is likely to occur on the time scale of lampricide applications (2-5 days), while niclosamide, the less selective lampricide, will undergo minimal direct photodegradation during its passage to the Great Lakes.

  4. Bleaching of the thermoluminescence of feldspars by selected wavelengths present in sunlight

    International Nuclear Information System (INIS)

    Robertson, G.B.; Prescott, J.R.; Hutton, J.T.

    1993-01-01

    Feldspars occur in many sediments, and dating them by thermoluminescence (TL) requires a knowledge of how efficiently sunlight bleaches these minerals. The relative bleaching efficiencies of various wavelengths have been investigated for four alkali feldspars and an oligoclase, using the natural TL of the samples and the artificial TL induced by laboratory irradiation, bleached by wavelengths in the range 322-550 nm. Ultraviolet wavelengths are more efficient than the longer wavelengths at bleaching all the glow-curve peaks and are responsible for most of the phototransfer from high-temperature peaks to low-temperature peaks. Some feldspars show an initial increase in TL intensity with bleaching. Two sanidines of similar bulk composition but different TL glow curves show different dependences on bleaching wavelength. In a sodic sanidine with a dominant 240 o C peak the energy required to bleach to 50% was a thousand times greater at 550 nm than at 322 nm. In contrast, another sanidine with a complex glow curve between 150 and 450 o C showed a much slower change in the 330 o C peak with wavelength - a factor of 10 between 322 and 550 nm - with a region between 400 and 500 nm which was almost independent of wavelength. This behaviour is explained by competing mechanisms of phototransfer and bleaching which depend on wavelength in different ways. (author)

  5. Sunlight and Vitamin D: The Bone and Cancer Connections (invited paper)

    International Nuclear Information System (INIS)

    Holick, M.F.

    2000-01-01

    Vitamin D plays an essential role for calcium metabolism and bone health. It has been estimated that 90 to 95% of our vitamin D requirement comes from casual exposure to sunlight. There is a wide variety of factors that strongly influence the cutaneous production of vitamin D. These include melanin pigmentation, latitude, time of day, sunscreen use, and aging. There is an association with increased risk and mortality to breast, colon, and prostrate cancer. There is evidence that 25-hydroxyvitamin D, the major circulating form of vitamin D, is directly metabolised in prostate, breast, colon, and skin cells to its active form 1,25-dihydroxyvitamin D. 1,25-Dihydroxyvitamin D 3 has the capacity to regulate cell proliferation and differentiation. Therefore, it may be that an increase in the cutaneous synthesis of vitamin D results in the increase in the production of 1,25(OH) 2 D in tissues not related to calcium metabolism that results in a decrease in malignancy. (author)

  6. Photocatalytic degradation of phenol by iodine doped tin oxide nanoparticles under UV and sunlight irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Al-Hamdi, Abdullah M.; Sillanpää, Mika [Laboratory of Green Chemistry, Lappeenranta University of Technology, Sammonkatu 12, 50130 Mikkeli (Finland); Dutta, Joydeep, E-mail: dutta@squ.edu.om [Chair in Nanotechnology, Water Research Center, Sultan Qaboos University, P.O. Box 17, 123 Al-Khoudh (Oman)

    2015-01-05

    Highlights: • A sol–gel method used to synthesize tin oxide nanoparticles. • Nanoparticles of tin oxide doped with different iodine concentrations. • Degradation studies carried up with UV–vis, TOC, HPLC and GC instruments. • 1% iodine doped tin dioxide showed maximum photodegradation efficiency. - Abstract: Iodine doped tin oxide (SnO{sub 2}:I) nanoparticles were prepared by sol–gel synthesis and their photocatalytic activities with phenol as a test contaminant were studied. In the presence of the catalysts, phenol degradation under direct sunlight was comparable to what was achieved under laboratory conditions. Photocatalytic oxidation reactions were studied by varying the catalyst loading, light intensity, illumination time, pH of the reactant and phenol concentration. Upon UV irradiation in the presence of SnO{sub 2}:I nanoparticles, phenol degrades very rapidly within 30 min, forming carboxylic acid which turns the solution acidic. Phenol degradation rate with 1% iodine doped SnO{sub 2} nanoparticles is at least an order of magnitude higher compared to the degradation achieved through undoped SnO{sub 2} nanoparticles under similar illumination conditions.

  7. SASKTRAN: A spherical geometry radiative transfer code for efficient estimation of limb scattered sunlight

    International Nuclear Information System (INIS)

    Bourassa, A.E.; Degenstein, D.A.; Llewellyn, E.J.

    2008-01-01

    The inversion of satellite-based observations of limb scattered sunlight for the retrieval of constituent species requires an efficient and accurate modelling of the measurement. We present the development of the SASKTRAN radiative transfer model for the prediction of limb scatter measurements at optical wavelengths by method of successive orders along rays traced in a spherical atmosphere. The component of the signal due to the first two scattering events of the solar beam is accounted for directly along rays traced in the three-dimensional geometry. Simplifying assumptions in successive scattering orders provide computational optimizations without severely compromising the accuracy of the solution. SASKTRAN is designed for the analysis of measurements from the OSIRIS instrument and the implementation of the algorithm is efficient such that the code is suitable for the inversion of OSIRIS profiles on desktop computers. SASKTRAN total limb radiance profiles generally compare better with Monte-Carlo reference models over a large range of solar conditions than the approximate spherical and plane-parallel models typically used for inversions

  8. Converting sunlight into audible sound by means of the photoacoustic effect: The Heliophone.

    Science.gov (United States)

    Roozen, N B; Glorieux, C; Liu, L; Rychtáriková, M; Van der Donck, T; Jacobs, A

    2016-09-01

    One hundred and thirty-five years after Alexander Graham Bell and his assistant Charles Sumner Tainter explored the photoacoustic effect, and about 40 years after Rosencwaig and Gersho modeled the effect in a photoacoustic cell configuration, the phenomenon is revisited in a "Heliophone" device that converts sunlight into sound. The light is focused on a carbon blackened copper coated Kapton foil in an acoustic cell by means of a compound parabolic collimator, and its intensity is modulated by a mechanical chopper. A horn is employed to make the sound audible without electronic amplification. The description of the photoacoustic effect that was introduced by Rosencwaig and Gersho is extended to a cell-horn configuration, in which the periodically heated air above the foil acts as an oscillating piston, driving acoustic waves in the horn. The pressure in the cavity-horn assembly is calculated by considering the air layer piston as an equivalent volume velocity source. The importance of the carbon black (soot) layer to enhance light absorption, but above all to enhance the photothermal excitation efficiency, is elucidated by means of an experimentally supported physical model.

  9. Photocatalytic degradation of phenol by iodine doped tin oxide nanoparticles under UV and sunlight irradiation

    International Nuclear Information System (INIS)

    Al-Hamdi, Abdullah M.; Sillanpää, Mika; Dutta, Joydeep

    2015-01-01

    Highlights: • A sol–gel method used to synthesize tin oxide nanoparticles. • Nanoparticles of tin oxide doped with different iodine concentrations. • Degradation studies carried up with UV–vis, TOC, HPLC and GC instruments. • 1% iodine doped tin dioxide showed maximum photodegradation efficiency. - Abstract: Iodine doped tin oxide (SnO 2 :I) nanoparticles were prepared by sol–gel synthesis and their photocatalytic activities with phenol as a test contaminant were studied. In the presence of the catalysts, phenol degradation under direct sunlight was comparable to what was achieved under laboratory conditions. Photocatalytic oxidation reactions were studied by varying the catalyst loading, light intensity, illumination time, pH of the reactant and phenol concentration. Upon UV irradiation in the presence of SnO 2 :I nanoparticles, phenol degrades very rapidly within 30 min, forming carboxylic acid which turns the solution acidic. Phenol degradation rate with 1% iodine doped SnO 2 nanoparticles is at least an order of magnitude higher compared to the degradation achieved through undoped SnO 2 nanoparticles under similar illumination conditions

  10. Sunlight-charged electrochromic battery based on hybrid film of tungsten oxide and polyaniline

    Science.gov (United States)

    Chang, Xueting; Hu, Ruirui; Sun, Shibin; Liu, Jingrong; Lei, Yanhua; Liu, Tao; Dong, Lihua; Yin, Yansheng

    2018-05-01

    Electrochromic (EC) energy storage devices that could realize the multifunctional integration of energy storage and electrochromism have gained much recent attention. Herein, an EC battery based on the hybrid film of W18O49 and polyaniline (PANI) is developed and assembled, which integrates energy storage and EC functions in one device. The W18O49/PANI-EC battery delivers a discharging capacity of 52.96 mA h g-1, which is about two times higher than that of the W18O49-EC battery. Sunlight irradiation could greatly promote the oxidation reactions of both W18O49 and PANI during the charging process of the W18O49/PANI-EC battery, thus effectively accelerating the charging rate. This work provides a green, convenient, environmentally friendly, and cost-free charging strategy for the EC energy systems and could further advance the development of the multifunctional EC devices based on the organic/inorganic composites.

  11. ZnO-graphene quantum dots heterojunctions for natural sunlight-driven photocatalytic environmental remediation

    Science.gov (United States)

    Kumar, Suneel; Dhiman, Ankita; Sudhagar, Pitchaimuthu; Krishnan, Venkata

    2018-07-01

    In this work, we report the formation of heterojunctions comprising of graphene quantum dots (GQD) decorated ZnO nanorods (NR) and its use as efficient photocatalysts for environmental remediation. The heterojunctions has been designed to be active both in the UV and visible light regions and anticipated utilize the maximum part of the solar light spectrum. In this view, we examined the photocatalytic performance of our heterojunctions towards the degradation of colored pollutant (methylene blue (MB) dye) and a colorless pollutant (carbendazim (CZ) fungicide) under sunlight irradiation. Compared to bare photocatalyst ZnO and GQD, the heterojunction with 2 wt% of GQD (ZGQD2) showed the best photocatalytic activity by effectively degrading (about 95%) of organic pollutants (MB and CZ) from water within a short span of 70 min. The superior photocatalytic activity of these ZnO-GQD heterojunctions could be attributed to efficient charge carrier separation lead suppressed recombination rate at photocatalyst interfaces. In addition to the enhanced light absorption from UV to visible region, the high specific surface area of ZGQD2 heterojunction (353.447 m2 g-1) also imparts strong adsorption capacity for pollutants over catalyst surface, resulting in high photoactivity. Based on the obtained results, band gap alignment at ZnO-GQD heterojunction and active species trapping experiments, a plausible mechanism is proposed for photocatalytic reaction. The excellent photostability and recyclability of the ZnO-GQD heterojunctions fostering as promising photocatalyst candidate for environmental remediation applications.

  12. Hydrogen at the Rooftop: Compact CPV-Hydrogen system to Convert Sunlight to Hydrogen

    KAUST Repository

    Burhan, Muhammad

    2017-12-27

    Despite being highest potential energy source, solar intermittency and low power density make it difficult for solar energy to compete with the conventional power plants. Highly efficient concentrated photovoltaic (CPV) system provides best technology to be paired with the electrolytic hydrogen production, as a sustainable energy source with long term energy storage. However, the conventional gigantic design of CPV system limits its market and application to the open desert fields without any rooftop installation scope, unlike conventional PV. This makes CPV less popular among solar energy customers. This paper discusses the development of compact CPV-Hydrogen system for the rooftop application in the urban region. The in-house built compact CPV system works with hybrid solar tracking of 0.1° accuracy, ensured through proposed double lens collimator based solar tracking sensor. With PEM based electrolyser, the compact CPV-hydrogen system showed 28% CPV efficiency and 18% sunlight to hydrogen (STH) efficiency, for rooftop operation in tropical region of Singapore. For plant designers, the solar to hydrogen production rating of 217 kWh/kg has been presented with 15% STH daily average efficiency, recorded from the long term field operation of the system.

  13. Hydrogen at the Rooftop: Compact CPV-Hydrogen system to Convert Sunlight to Hydrogen

    KAUST Repository

    Burhan, Muhammad; Wakil Shahzad, Muhammad; Ng, Kim Choon

    2017-01-01

    Despite being highest potential energy source, solar intermittency and low power density make it difficult for solar energy to compete with the conventional power plants. Highly efficient concentrated photovoltaic (CPV) system provides best technology to be paired with the electrolytic hydrogen production, as a sustainable energy source with long term energy storage. However, the conventional gigantic design of CPV system limits its market and application to the open desert fields without any rooftop installation scope, unlike conventional PV. This makes CPV less popular among solar energy customers. This paper discusses the development of compact CPV-Hydrogen system for the rooftop application in the urban region. The in-house built compact CPV system works with hybrid solar tracking of 0.1° accuracy, ensured through proposed double lens collimator based solar tracking sensor. With PEM based electrolyser, the compact CPV-hydrogen system showed 28% CPV efficiency and 18% sunlight to hydrogen (STH) efficiency, for rooftop operation in tropical region of Singapore. For plant designers, the solar to hydrogen production rating of 217 kWh/kg has been presented with 15% STH daily average efficiency, recorded from the long term field operation of the system.

  14. The relationship between solar activity and the H and K line cores in integrated sunlight

    International Nuclear Information System (INIS)

    Jebsen, D.E.; Mitchell, W.E. Jr.

    1978-01-01

    In this paper the authors present and analyze new data on the cores of the H and K lines of ionized calcium in the spectrum of integrated sunlight. The intensities of the components Hsub(2γ), H 3 , Hsub(2r), Ksub(2γ), K 3 , and Ksub(2r) in the line cores were measured in terms of the continuum intensity at 4000 A during a solar rotation in September 1969. Other data on these components, obtained at or close to the time of solar minimum (September 1964) and solar maximum (September 1968), were also included. The intensities of these features are compared with two indices of solar activity: the Ca II plage index and the 2800 MHZ signal. The average correlation coefficients between the intensities of the measured features and those indices were 0.69 and 0.64, respectively. The results are consistent with those of Bumba and Ruzickova-Topolova (1967) for a solar rotation period in 1965. The method and results should provide a detailed quantitative basis for the study of the activity cycles and rotation periods of solar-type stars. (Auth.)

  15. Periphyton ecology of glacial and snowmelt streams, Ny-Alesund, Svalbard: presence of mineral particles in water and their erosive activity

    Czech Academy of Sciences Publication Activity Database

    Kubečková, Klára; Elster, Josef; Kanda, H.

    2001-01-01

    Roč. 123, - (2001), s. 141-172 ISSN 1438-9134. [International conference: Algae and extreme environments. Třeboň, 11.09.2000-16.09.2000] R&D Projects: GA AV ČR KSK6005114; GA AV ČR IAA6005002 Institutional research plan: CEZ:AV0Z6005908; CEZ:MSM 123100004 Keywords : Periphyton * species diversity and productivity * the Arctic * glacial snowmelt streams * physical disturbances erosive discharge * water turbidity Subject RIV: EA - Cell Biology Impact factor: 0.488, year: 2000

  16. Relationship Between Satellite-Derived Snow Cover and Snowmelt-Runoff Timing and Stream Power in the Wind River Range, Wyoming

    Science.gov (United States)

    Hall, Dorothy K.; Foster, James L.; DiGirolamo, Nicolo E.; Riggs, George A.

    2010-01-01

    Earlier onset of springtime weather including earlier snowmelt has been documented in the western United States over at least the last 50 years. Because the majority (>70%) of the water supply in the western U.S. comes from snowmelt, analysis of the declining spring snowpack (and shrinking glaciers) has important implications for streamflow management. The amount of water in a snowpack influences stream discharge which can also influence erosion and sediment transport by changing stream power, or the rate at which a stream can do work such as move sediment and erode the stream bed. The focus of this work is the Wind River Range (WRR) in west-central Wyoming. Ten years of Moderate-Resolution Imaging Spectroradiometer (MODIS) snow-cover, cloud- gap-filled (CGF) map products and 30 years of discharge and meteorological station data are studied. Streamflow data from six streams in the WRR drainage basins show lower annual discharge and earlier snowmelt in the decade of the 2000s than in the previous three decades, though no trend of either lower streamflow or earlier snowmelt was observed using MODIS snow-cover maps within the decade of the 2000s. Results show a statistically-significant trend at the 95% confidence level (or higher) of increasing weekly maximum air temperature (for three out of the five meteorological stations studied) in the decade of the 1970s, and also for the 40-year study period. MODIS-derived snow cover (percent of basin covered) measured on 30 April explains over 89% of the variance in discharge for maximum monthly streamflow in the decade of the 2000s using Spearman rank correlation analysis. We also investigated stream power for Bull Lake Creek Above Bull Lake from 1970 to 2009; a statistically-significant end toward reduced stream power was found (significant at the 90% confidence level). Observed changes in streamflow and stream power may be related to increasing weekly maximum air temperature measured during the 40-year study period. The

  17. Seasonal Influenza: An Overview

    Science.gov (United States)

    Li, Christina; Freedman, Marian

    2009-01-01

    Seasonal influenza is a major cause of morbidity and mortality in the United States. It also has major social and economic consequences in the form of high rates of absenteeism from school and work as well as significant treatment and hospitalization costs. In fact, annual influenza epidemics and the resulting deaths and lost days of productivity…

  18. Seasonal atmospheric extinction

    International Nuclear Information System (INIS)

    Mikhail, J.S.

    1979-01-01

    Mean monochromatic extinction coefficients at various wavelengths at the Kottamia Observatory site have shown the existence of a seasonal variation of atmospheric extinction. The extinction of aerosol compontnts with wavelengths at winter represent exceedingly good conditions. Spring gives the highest extinction due to aerosol. (orig.)

  19. Seasonality of Rural Finance

    OpenAIRE

    Khandker, Shahidur R.; Samad, Hussain A.; Badruddoza, Syed

    2017-01-01

    Simultaneity of borrowing, withdrawal of savings, and loan defaults due to the pronounced seasonality of agriculture often leads to investment failure of rural financial institutions. Lack of borrowing leads to lack of in-come- and consumption-smoothing, and in turn, causes inefficient resource allocation by rural households. Financial institutions that are active in rural areas take diffe...

  20. The Hungry Season

    African Journals Online (AJOL)

    start to go some way towards addressing this fundamental question. A delightful animation of The Hungry Season, commissioned by Leonie Joubert and funded by the University of Cape Town's Criminology. Department and the Embassy of Finland, is available online at http://www.youtube.com/ watch?v=iX77NZttLKo.

  1. Antiviral Drugs: Seasonal Flu

    Centers for Disease Control (CDC) Podcasts

    2010-09-29

    In this podcast, Dr. Joe Bresee explains the nature of antiviral drugs and how they are used for seasonal flu.  Created: 9/29/2010 by National Center for Immunization and Respiratory Diseases (NCIRD).   Date Released: 9/29/2010.

  2. Warning Signs: Seasonal Flu

    Centers for Disease Control (CDC) Podcasts

    2010-09-29

    In this podcast, Dr. Joe Bresee describes the main symptoms of seasonal flu and when it is serious enough to seek medical help.  Created: 9/29/2010 by National Center for Immunization and Respiratory Diseases (NCIRD).   Date Released: 9/29/2010.

  3. Take Three: Seasonal Flu

    Centers for Disease Control (CDC) Podcasts

    2010-09-29

    In this podcast, Dr. Joe Bresee describes how to keep from getting seasonal flu and spreading it to others by taking these three steps.  Created: 9/29/2010 by National Center for Immunization and Respiratory Diseases (NCIRD).   Date Released: 9/29/2010.

  4. Scenario approach for the seasonal forecast of Kharif flows from the Upper Indus Basin

    Science.gov (United States)

    Fraz Ismail, Muhammad; Bogacki, Wolfgang

    2018-02-01

    Snow and glacial melt runoff are the major sources of water contribution from the high mountainous terrain of the Indus River upstream of the Tarbela reservoir. A reliable forecast of seasonal water availability for the Kharif cropping season (April-September) can pave the way towards better water management and a subsequent boost in the agro-economy of Pakistan. The use of degree-day models in conjunction with satellite-based remote-sensing data for the forecasting of seasonal snow and ice melt runoff has proved to be a suitable approach for data-scarce regions. In the present research, the Snowmelt Runoff Model (SRM) has not only been enhanced by incorporating the glacier (G) component but also applied for the forecast of seasonal water availability from the Upper Indus Basin (UIB). Excel-based SRM+G takes account of separate degree-day factors for snow and glacier melt processes. All-year simulation runs with SRM+G for the period 2003-2014 result in an average flow component distribution of 53, 21, and 26 % for snow, glacier, and rain, respectively. The UIB has been divided into Upper and Lower parts because of the different climatic conditions in the Tibetan Plateau. The scenario approach for seasonal forecasting, which like the Ensemble Streamflow Prediction method uses historic meteorology as model forcings, has proven to be adequate for long-term water availability forecasts. The accuracy of the forecast with a mean absolute percentage error (MAPE) of 9.5 % could be slightly improved compared to two existing operational forecasts for the UIB, and the bias could be reduced to -2.0 %. However, the association between forecasts and observations as well as the skill in predicting extreme conditions is rather weak for all three models, which motivates further research on the selection of a subset of ensemble members according to forecasted seasonal anomalies.

  5. T198. A SCHIZOPHRENIA-LIKE BIRTH SEASONALITY AMONG MATHEMATICIANS AND AN OPPOSITE SEASONALITY AMONG BIOLOGISTS: MORE EVIDENCE IMPLICATING BIMODAL RHYTHMS OF GENERAL BIRTHS

    Science.gov (United States)

    Marzullo, Giovanni

    2018-01-01

    Abstract Background Based on early-20th century births, a pre-electric illumination time of comparatively normal human exposure to sunlight, studies of schizophrenia (SCZ) found a birth seasonality with two opposite effects: a SCZ-liability peak among subjects born around late-February and an equally significant SCZ-resistance peak among those born six months later, around late-August. We previously investigated this rhythm in connection with a sunlight-dependent bimodal rhythm of general births that, prior to the full advent of electric lighting (but not later), occurred ubiquitously in non-equatorial parts of the world. We found that the SCZ-liability peak coincided with a first, Feb-Mar peak of general-population births (the GP1) while the SCZ-resistance peak coincided with a second, Aug-Sep peak of those births (the GP2). Moreover, in a study of hand and visual-field preferences among professional baseball players, we found the SCZ-liability, GP1-coincident seasonality among players with preferences denoting cerebral asymmetry “deficits” (CADs) and the SCZ-resistance, GP2-coincident seasonality among those with preferences denoting cerebral asymmetry “excesses.” Also, in a study suggested by associations of CADs with artistic abilities, we found the SCZ-liability, GP1-coincident seasonality among groups representing visual, performing and literary art “creators” (VPL-Artists) and the SCZ-resistance, GP2-coincident seasonality among groups representing art critics, historians, curators and other art “observers” (Para-Artists). Together, these findings suggested, as one possibility (but see later), that the SCZ-liability, CAD effects and artistic abilities could all three represent traits genetically or otherwise selected into the GP1 excess population of newborns and out of the GP2 population. The present study of “scientists” was initially aimed at the purported arts/science antithesis. Methods Birth seasonalities were examined among early

  6. Sunlight-Driven Forging of Amide/Ester Bonds from Three Independent Components: An Approach to Carbamates.

    Science.gov (United States)

    Zhao, Yating; Huang, Binbin; Yang, Chao; Chen, Qingqing; Xia, Wujiong

    2016-11-04

    A photoredox catalytic route to carbamates enabled by visible irradiation (or simply sunlight) has been developed. This process leads to a novel approach to the construction of heterocyclic rings wherein the amide or ester motifs of carbamates were assembled from three isolated components. Large-scale experiments were realized by employing continuous flow techniques, and reuse of photocatalyst demonstrated the green and sustainable aspects of this method.

  7. Coupled optic-thermodynamic analysis of a novel wireless power transfer system using concentrated sunlight for space applications

    International Nuclear Information System (INIS)

    Zhong, Ming-Liang; Li, Yun-Ze; Mao, Yu-Feng; Liang, Yi-Hao; Liu, Jia

    2017-01-01

    Highlights: • A novel space wireless power transfer system is proposed. • Concentrated sunlight is used as the medium to avoid multiple conversions. • Fresnel lens and optical fiber bundle make the system compact and space-qualified. • Coupled optic-thermodynamic model is developed to analyze link efficiencies. • End-to-end efficiency achieved is as twice as that of microwave or laser system. - Abstract: The energy generation and supply for in-orbit spacecraft have become an urgent problem concerning efficient and economical utilization of spacecraft formation flying. To fill the gap between the requirement of inter-spacecraft energy transfer and the development of wireless power transfer, this paper presents a novel wireless power transfer system whose transmission medium is concentrated sunlight. The system concentrates sunlight using a Fresnel lens, and changes the direction of concentrated sunlight beam with optical fibers. The light energy is converted to thermal form by a heat collector, and then it is utilized to generate electricity by a Stirling engine integrated with linear alternator. Equipments employed on fractionated spacecraft shall be supported by this electric energy. A coupled optic-thermodynamic model was developed to analyze system link efficiencies. This system offers characteristics such as high flexibility, relatively low cost for launch and maintenance, and most importantly, high end-to-end efficiency. Simulation results show that the geometric concentration ratio and the temperature ratio of expansion and compression spaces are two key parameters of this system. Output power of 234.3 W was achieved on the distance of 100 m, and the end-to-end efficiency of the system was above 20%.

  8. Pengaruh Suhu Terhadap Tegangan Permukaan Sabun Cuci Piring Cair Buatan Sendiri, Sunlight, Dan S.O.S

    OpenAIRE

    Siahaan, Okio Patar

    2011-01-01

    The effect of temperature on the surface tension of homemade liquid dish soap, Sunlight, and SOS was carried out. The temperatures was variated 280C(without heating), 300C, 400C and 500C. The homemade liquid dish soap was prepared by using an active ingredients. The active ingredient of the liquid dishwashing soap were sodium lauryl ether sulphate, sodium alkyl benzene sulfonate, and sodium lauril ether sulfate, respectively. The determination of surface tension was based the increasing of t...

  9. Quantification of ultraviolet radiation-induced DNA damage in the urine of Swedish adults and children following exposure to sunlight

    OpenAIRE

    Liljendahl, Tove Sandberg; Kotova, Natalia; Segerbäck, Dan

    2012-01-01

    DNA damage following exposure to ultraviolet radiation (UVR) is important in skin cancer development. The predominant photoproduct, cyclobutane thymine dimer (T=T), is repaired and excreted in the urine, where it provides a biomarker of exposure. To quantify urinary T=T levels after recreational sunlight exposure in adults and children. Average UVR doses were measured with personal dosimeters. Urinary T=T was analysed with (32)P-postlabelling. ResuLTS: Background levels of T=T increased...

  10. The effect of seasonal changes and climatic factors on suicide attempts of young people.

    Science.gov (United States)

    Akkaya-Kalayci, Türkan; Vyssoki, Benjamin; Winkler, Dietmar; Willeit, Matthaeus; Kapusta, Nestor D; Dorffner, Georg; Özlü-Erkilic, Zeliha

    2017-11-15

    Seasonal changes and climatic factors like ambient temperature, sunlight duration and rainfall can influence suicidal behavior. This study analyses the relationship between seasonal changes and climatic variations and suicide attempts in 2131 young patients in Istanbul, Turkey. In our study sample, there was an association between suicide attempts in youths and seasonal changes, as suicide attempts occurred most frequently during summer in females as well as in males. Furthermore, there was a positive correlation between the mean temperature over the past 10 days and temperature at the index day and suicide attempts in females. After seasonality effects were mathematically removed, the mean temperature 10 days before a suicide attempt remained significant in males only, indicating a possible short-term influence of temperature on suicide attempts. This study shows an association between suicide attempts of young people and climatic changes, in particular temperature changes as well as seasonal changes. Therefore, the influence of seasonal changes and climatic factors on young suicide attempters should get more attention in research to understand the biopsychosocial mechanisms playing a role in suicide attempts of young people. As suicide attempts most frequently occur in young people, further research is of considerable clinical importance.

  11. Molecular identification of host feeding patterns of snow-melt mosquitoes (Diptera: Culicidae): potential implications for the transmission ecology of Jamestown Canyon virus.

    Science.gov (United States)

    Murdock, C C; Olival, Kevin J; Perkins, Susan L

    2010-03-01

    We collected blood-fed, snow-melt mosquitoes (Culicidae: Culiseta and Aedes) to describe the feeding patterns of potential mosquito vectors of Jamestown Canyon virus (JCV, Bunyaviridae: Orthobunyavirus). JCV is an arthropod-borne, zoonotic virus with deer as the primary amplifying host in western alpine ecosystems. We collected mosquitoes from natural resting areas, fiber pots, and carbon-dioxide baited miniature light traps in the Colorado Rocky Mountains in 2007. We conducted two polymerase chain reactions to amplify and sequence vertebrate DNA extracted from blood-fed mosquitoes, which yielded comparable, but not identical, results. Mammal-specific primers found mule deer (Odocoileus hemionus) and elk (Cervus elaphus canadensis) as the source of all bloodmeals. To determine if unamplified bloodmeals were from nonmammalian sources, we screened all samples with conserved vertebrate primers, which confirmed the initial polymerase chain reaction results, but also found porcupine (Erethizon dorsatum) and human (Homo sapiens) as additional bloodmeal sources. We consistently found that mule deer were the primary hosts for mosquitoes in this system. These results suggest that snow-melt mosquitoes, in particular A. cataphylla, may be important vectors in western JCV alpine systems and may also act as a bridge vector for JCV from cervid virus reservoirs to humans.

  12. Extreme air pollution events in Hokkaido, Japan, traced back to early snowmelt and large-scale wildfires over East Eurasia: Case studies.

    Science.gov (United States)

    Yasunari, Teppei J; Kim, Kyu-Myong; da Silva, Arlindo M; Hayasaki, Masamitsu; Akiyama, Masayuki; Murao, Naoto

    2018-04-25

    To identify the unusual climate conditions and their connections to air pollutions in a remote area due to wildfires, we examine three anomalous large-scale wildfires in May 2003, April 2008, and July 2014 over East Eurasia, as well as how products of those wildfires reached an urban city, Sapporo, in the northern part of Japan (Hokkaido), significantly affecting the air quality. NASA's MERRA-2 (the Modern-Era Retrospective analysis for Research and Applications, Version 2) aerosol re-analysis data closely reproduced the PM 2.5 variations in Sapporo for the case of smoke arrival in July 2014. Results show that all three cases featured unusually early snowmelt in East Eurasia, accompanied by warmer and drier surface conditions in the months leading to the fires, inducing long-lasting soil dryness and producing climate and environmental conditions conducive to active wildfires. Due to prevailing anomalous synoptic-scale atmospheric motions, smoke from those fires eventually reached a remote area, Hokkaido, and worsened the air quality in Sapporo. In future studies, continuous monitoring of the timing of Eurasian snowmelt and the air quality from the source regions to remote regions, coupled with the analysis of atmospheric and surface conditions, may be essential in more accurately predicting the effects of wildfires on air quality.

  13. Increased concentrations of polycyclic aromatic hydrocarbons in Alpine streams during annual snowmelt: investigating effects of sampling method, site characteristics, and meteorology.

    Science.gov (United States)

    Shahpoury, Pourya; Hageman, Kimberly J; Matthaei, Christoph D; Alumbaugh, Robert E; Cook, Michelle E

    2014-10-07

    Silicone passive samplers and macroinvertebrates were used to measure time-integrated concentrations of polycyclic aromatic hydrocarbons (PAHs) in alpine streams during annual snowmelt. The three sampling sites were located near a main highway in Arthur's Pass National Park in the Southern Alps of New Zealand. A similar set of PAH congeners, composed of 2-4 rings, were found in silicone passive samplers and macroinvertebrates. The background PAH concentrations were similar at all sites, implying that proximity to the highway did not affect concentrations. In passive samplers, an increase of PAH concentrations by up to seven times was observed during snowmelt. In macroinvertebrates, the concentration changes were moderate; however, macroinvertebrate sampling did not occur during the main pulse observed in the passive samplers. The extent of vegetation in the catchment appeared to affect the concentration patterns seen at the different stream sites. A strong correlation was found between PAH concentrations in passive samplers and the amount of rainfall in the study area, indicating that the washout of contaminants from snowpack by rainfall was an important process.

  14. Effect of exposure to sunlight and phosphorus-limitation on bacterial degradation of coloured dissolved organic matter (CDOM) in freshwater.

    Science.gov (United States)

    Kragh, Theis; Søndergaard, Morten; Tranvik, Lars

    2008-05-01

    This study reports on the interacting effect of photochemical conditioning of dissolved organic matter and inorganic phosphorus on the metabolic activity of bacteria in freshwater. Batch cultures with lake-water bacteria and dissolved organic carbon (DOC) extracted from a humic boreal river were arranged in an experimental matrix of three levels of exposure to simulated sunlight and three levels of phosphorus concentration. We measured an increase in bacterial biomass, a decrease in DOC and bacterial respiration as CO(2) production and O(2) consumption over 450 h. These measurements were used to calculate bacterial growth efficiency (BGE). Bacterial degradation of DOC increased with increasing exposure to simulated sunlight and availability of phosphorus and no detectable growth occurred on DOC that was not pre-exposed to simulated sunlight. The outcome of photochemical degradation of DOC changed with increasing availability of phosphorus, resulting in an increase in BGE from about 5% to 30%. Thus, the availability of phosphorus has major implications for the quantitative transfer of carbon in microbial food webs.

  15. Morphology-controlled electrodeposition of Cu2O microcrystalline particle films for application in photocatalysis under sunlight

    International Nuclear Information System (INIS)

    Wu, Guodong; Zhai, Wei; Sun, Fengqiang; Chen, Wei; Pan, Zizhao; Li, Weishan

    2012-01-01

    Graphical abstract: Display Omitted Highlights: ► PEG was used to electro-deposit Cu 2 O microcrystalline particle films. ► Morphologies of Cu 2 O microcrystals could be controlled by the amount of PEG. ► The films showed regularly varied photocatalytic activities under sunlight. ► The films could be recycled and showed stable activities. -- Abstract: Morphology-controlled Cu 2 O microcrystalline particle films had been successfully electrodeposited on tin-doped indium oxide glass substrates in CuSO 4 solutions containing different amounts of polyethylene glycol (PEG) additives. With an increase of PEG, microcrystals gradually changed from irregular shapes to cubes, octahedrons, and spherical shapes. Sizes increasingly became smaller with an increase of PEG under the same deposition time. These films had been first used as recyclable photocatalysts and showed excellent and photocatalytic activities in photodegradation of methylene blue (MB) under sunlight. Activities were regularly varied relative to the morphologies of films controlled by the amount of PEG and could be further enhanced by adding a little amount of hydrogen peroxide in the MB solution. The method for controllable preparation of Cu 2 O microcrystals with photocatalytic activities was simple and inexpensive. The as-prepared particle films could also be used in photodegradation of many other pollutants under sunlight.

  16. Dietary intakes of expeditioners during prolonged sunlight deprivation in polar enviroments do not support bone health.

    Science.gov (United States)

    Iuliano, Sandra; Ayton, Jeff

    2015-01-01

    Background Early Antarctic expeditions were plagued by nutrient deficiencies, due to lack of fresh food and reliance on preserved foods. Modern Antarctic expeditioners also require provisions to be shipped in, but improved knowledge and storage options ensure foods are nutritionally sound. Despite this, nutritional imbalances are observed. Objectives To determine the adequacy of dietary intake of Antarctic expeditioners, with reference to bone health. Design Dietary intake was determined on 225 adults (mean age 42±11 years, 16% female) during 12-month deployments at Australian Antarctic stations from 2004 to 2010, using weighed 3-day food records. Nutrient intake was analysed using FoodWorks. Foods were divided into the 5 food groups according to the Australian Guide to Healthy Eating. Results Men consumed below the recommended levels [recommended daily intake (RDI)/adequate intakes (AI)] of calcium (79±42% of RDI, p<0.001), magnesium (83±34% of RDI, p<0.001), potassium (86±29% of AI, p<0.001) and fibre (75±30% of AI, p<0.001), and above the upper limit (UL) for sodium (125±48% of UL p<0.001), whereas women consumed below the recommended levels of calcium (68±21% of RDI, p<0.001) and iron (73±37% of RDI, p<0.001). Vitamin D intake is not substantial (<150 IU/d). Men consumed more alcohol than women (18±24 g/d vs. 10±13 g/d, p<0.05), nearer the guideline of ≤20 g/d. Men and women consumed approximately 1 serving of dairy food per day, and 3 of 5 recommended vegetable servings. Discretionary foods were consumed in excess of recommended. Conclusions Improving consumption of calcium-rich (dairy) foods better supports bone health during sunlight deprivation. Increasing vegetable intake to recommended levels will increase fibre, potassium and magnesium intakes. The challenge is the logistics of providing these foods throughout the year.

  17. Enhanced photocatalytic degradation of dyes under sunlight using biocompatible TiO2 nanoparticles

    Science.gov (United States)

    Bharati, B.; Sonkar, A. K.; Singh, N.; Dash, D.; Rath, Chandana

    2017-08-01

    As TiO2 is one of the most popular photocatalysts, we have studied here the photocatalytic degradation of the most common dyestuffs like rhodamine B (RhB), congo red (CR) and methylene blue (MB), which mainly come from the textile and photographic industries using nanoparticles of TiO2. Nanoparticles of TiO2 synthesized through a simple and cost effective sol-gel technique crystallizes in the anatase phase, showing a band gap less than that of bulk value. Particles consisting of coherently scattered domains of size 33 nm are found to be agglomerated and polycrystalline in nature. While the degradation rates of MB, CR and RhB after irradiating with a renewable source of energy, i.e. sunlight, show 100% degradation, TiO2 irradiated with UV light of 4.8 eV shows a much slower degradation rate. To use the waste water after photocatalysis, we examine further the biocompatibile nature of the TiO2 nanoparticles by platelet interaction activity, hemolysis effect and MTT assay. It is worth mentioning here that TiO2 nanoparticles are found to be highly hemocompatible, show no platelet aggregation, and the level of intracellular ROS in human platelets does not show significant change in ROS level. We conclude that TiO2 nanoparticles constitute an excellent photocatalyst and biocompatible material, and that after photocatalytic degradation of dye effluents obtained from textile industries, purified water can be used in agriculture and domestic sectors.

  18. Antiradical capacity and polyphenol composition of asparagus spears varieties cultivated under different sunlight conditions.

    Science.gov (United States)

    Kulczyński, Bartosz; Kobus-Cisowska, Joanna; Kmiecik, Dominik; Gramza-Michałowska, Anna; Golczak, Dorota; Korczak, Józef

    2016-01-01

    Asparagus officinalis has a high nutritional value. Asparagus is rich in a number of bioactive compounds, mainly flavonoids (quercetin), glutathione, vitamin C, vitamin E, fructans (inulin and fructooligosaccharides) and phytosterols (b-sitosterol). These compounds may play an important role in human health. The purpose of this study was to examine the antioxidant potential and polyphenol composition of white, pale-colored and green asparagus spears of different cultivars. Investigations were conducted on different asparagus spear extracts. The study included three colors of asparagus (white, pale-colored and green) from five different cultivars subjected to the ethanol extraction procedure. Total phenolic content was also determined by the Folin-Ciocalteu method. Polyphenol (phenolic acids and flavonols) composition was estimated using the HPLC method. The antioxidant properties of extracts were examined using DPPH, ABTS and metal ion chelating assays. The highest contents of phenolic and flavonoids were observed in green asparagus from Grolim and the lowest in pale-colored asparagus from Gyjmlin. It was found that both the color of asparagus and the cultivar had a significant effect on the composition of phenolic acid and flavonols. Radical scavenging activity toward DPPH• and ABTS was highest for green asparagus cv. Grolim and Eposs. The greatest number of Fe ions was chelated by samples of green asparagus cv. Grolim and Huchel's Alpha and pale-colored asparagus cv. Huchel's Alpha. It was shown that the antioxidant activity of asparagus spears measured by antiradical and chelating activity test depends on variety and color. The highest activity was found in green asparagus and the lowest was identified in white asparagus extracts. It has also been clarified that changes in flavonol and phenolic acid composition and increases in their diversity depends on growing with sunlight and variety. Asparagus can provide a valuable source of phenolic compounds in the

  19. A practical demonstration of water disinfection using TiO2 films and sunlight.

    Science.gov (United States)

    Gelover, Silvia; Gómez, Luis A; Reyes, Karina; Teresa Leal, Ma

    2006-10-01

    The scope of this study is the assessment of the efficiency of solar disinfection by heterogeneous photocatalysis with sol-gel immobilized (titanium dioxide) TiO2 films over glass cylinders. The solar disinfection process known as SODIS was considered as a reference. Spring water naturally polluted with coliform bacteria was exposed to sunlight in plastic bottles with and without TiO2 over simple solar collectors and the disinfection effectiveness was measured. Total and fecal coliforms quantification was performed by means of the chromogenic substrate method in order to obtain the efficiency of each disinfection treatment. The disinfection with TiO2 was more efficient than the SODIS process, inactivating total coliforms as well as fecal coliforms. On a sunny day (more than 1000 W m(-2) irradiance), it took the disinfection with immobilized TiO2 15 min of irradiation to inactivate the fecal coliforms to make them undetectable. For inactivation of total coliforms, 30 min was required, so that in less than half the time it takes SODIS, the treated water complies with the microbial standards for drinking water in Mexico. Another important part of this study has been to determine the bacterial regrowth in water after the disinfection processes were tested. After SODIS, bacterial regrowth of coliforms was observed. In contrast, when using the TiO2 catalyst, coliforms regrowth was not detected, neither for total nor for fecal coliforms. The disinfection process using TiO2 kept treated water free of coliforms at least for seven days after sun irradiation. This demonstration opens the possibility of application of this simple method in rural areas of developing countries.

  20. Daytime Cognitive Performance in Response to Sunlight or Fluorescent Light Controlling for Sleep Duration

    Science.gov (United States)

    Ramos, Jhanic; Zamos, Adela; Rao, Rohit; Flynn-Evans, Erin

    2015-01-01

    Light is the primary synchronizer of the human circadian rhythm and also has acute alerting effects. Our study involves and comparing the alertness, performance and sleep of participants in the NASA Ames Sustainability Base, which uses sunlight as its primary light source, to in a traditional office building which uses overhead florescent lighting and varying exposure to natural light. The purpose of this study is to determine whether the use of natural lighting as a primary light source improves daytime cognitive function and promotes nighttime sleep. Participants from the Sustainability Base will be matched by gender and age to individuals working in other NASA buildings. In a prior study we found no differences in performance between those working in the Sustainability Base and those working in other buildings. Unexpectedly, we found that the average sleep duration among participants in both buildings was short, which likely obscured our ability to detect a difference the effect of light exposure on alertness. Given that such sleep deprivation has negative effects on cognitive performance, in this iteration of the study we are asking the participants to maintain a regular schedule with eight hours in bed each night in order to control for the effect of self-selected sleep restriction. Over the course of one week, we will ask the participants to wear actiwatches continuously, complete a psychomotor vigilance task (PVT) and digit symbol substitution task (DSST) three times per day, and keep daily sleepwork diaries. We hope that this study will provide data to support the idea that natural lighting and green architectural design are optimal to enhance healthy nighttime sleep patterns and daytime cognitive performance.

  1. Reusable sunlight activated photocatalyst Ag3PO4 and its significant antibacterial activity

    International Nuclear Information System (INIS)

    Thiyagarajan, Shankar; Singh, Sarika; Bahadur, D.

    2016-01-01

    A simple and surfactant free soft chemical approach is adopted for the successful synthesis of Ag 3 PO 4 nanoparticles (NPs) at room temperature. The obtained Ag 3 PO 4 NPs are nearly spherical in shape with a size of 250 ± 50 nm. These NPs are highly efficient for the degradation of three organic dyes (methylene blue, rhodamine B and methyl orange) under four different types of light sources. In this case, the superior photocatalytic activity is mainly driven by singlet oxygen radicals and it is confirmed through the electron spin resonance (ESR) spin trapping technique, using several quenchers/sources. Notably, these NPs have the ability to absorb large portion of solar spectrum and therefore it displays higher efficiency under sunlight as compared to UV-C light and a 60 W household compact fluorescence lamp (CFL). Furthermore, these NPs exhibit excellent colloidal stability and recycling capability for the degradation of dyes. In addition, it possesses significant antibacterial activity with complete inhibition of bacterial pathogen, Escherichia coli at a very low concentration (0.01 mg/mL) after a mere 15 min of incubation time. The inhibition of bacterial growth is also suggested from the generation of intracellular reactive oxygen species (ROS) in E. coli by fluorescence microscopy. Thus, these NPs may provide a potential outcome for the environmental remediation. - Graphical abstract: Schematic representation of the mechanism involved in photodegradation of organic dyes and inhibition of bacterial growth using Ag 3 PO 4 nanoparticles. - Highlights: • Excellent catalytic activity for dyes degradation under different light sources. • Mechanism involving catalyst mediated ROS generation in photocatalysis suggested. • Good recycling capability of Ag 3 PO 4 even after the fifth cycles. • Extraordinary antibacterial activity of Ag 3 PO 4 after a very short incubation time. • Detection of intracellular ROS in bacterial cells by fluorescence

  2. Identification of symmetric and asymmetric responses in seasonal streamflow globally to ENSO phase

    Science.gov (United States)

    Lee, Donghoon; Ward, Philip J.; Block, Paul

    2018-04-01

    The phase of the El Niño Southern Oscillation (ENSO) has large-ranging effects on streamflow and hydrologic conditions globally. While many studies have evaluated this relationship through correlation analysis between annual streamflow and ENSO indices, an assessment of potential asymmetric relationships between ENSO and streamflow is lacking. Here, we evaluate seasonal variations in streamflow by ENSO phase to identify asymmetric (AR) and symmetric (SR) spatial pattern responses globally and further corroborate with local precipitation and hydrological condition. The AR and SR patterns between seasonal precipitation and streamflow are identified at many locations for the first time. Our results identify strong SR patterns in particular regions including northwestern and southern US, northeastern and southeastern South America, northeastern and southern Africa, southwestern Europe, and central-south Russia. The seasonally lagged anomalous streamflow patterns are also identified and attributed to snowmelt, soil moisture, and/or cumulative hydrological processes across river basins. These findings may be useful in water resources management and natural hazards planning by better characterizing the propensity of flood or drought conditions by ENSO phase.

  3. Effect of Ambient Sunlight Intensity on the Temporal Phenolic Profiles of Vitis Vinifera L. Cv. Chardonnay During the Ripening Season -- A Field Study.

    Czech Academy of Sciences Publication Activity Database

    Šebela, David; Turóczy, Zoltán; Olejníčková, Julie; Kumšta, M.; Sotolář, R.

    2017-01-01

    Roč. 38, č. 1 (2017), s. 94-102 ISSN 0253-939X R&D Projects: GA ČR GA522/09/1565; GA MŠk(CZ) LO1415; GA MŠk(CZ) LM2015061 Institutional support: RVO:67179843 Keywords : abiotic stress * catechin * grape berries * OD 280nm * UV light * viticulture Subject RIV: EH - Ecology, Behaviour OBOR OECD: Environmental sciences (social aspects to be 5.7) Impact factor: 0.873, year: 2016

  4. Sunlight Modulates Fruit Metabolic Profile and Shapes the Spatial Pattern of Compound Accumulation within the Grape Cluster.

    Science.gov (United States)

    Reshef, Noam; Walbaum, Natasha; Agam, Nurit; Fait, Aaron

    2017-01-01

    Vineyards are characterized by their large spatial variability of solar irradiance (SI) and temperature, known to effectively modulate grape metabolism. To explore the role of sunlight in shaping fruit composition and cluster uniformity, we studied the spatial pattern of incoming irradiance, fruit temperature and metabolic profile within individual grape clusters under three levels of sunlight exposure. The experiment was conducted in a vineyard of Cabernet Sauvignon cv. located in the Negev Highlands, Israel, where excess SI and midday temperatures are known to degrade grape quality. Filtering SI lowered the surface temperature of exposed fruits and increased the uniformity of irradiance and temperature in the cluster zone. SI affected the overall levels and patterns of accumulation of sugars, organic acids, amino acids and phenylpropanoids, across the grape cluster. Increased exposure to sunlight was associated with lower accumulation levels of malate, aspartate, and maleate but with higher levels of valine, leucine, and serine, in addition to the stress-related proline and GABA. Flavan-3-ols metabolites showed a negative response to SI, whereas flavonols were highly induced. The overall levels of anthocyanins decreased with increased sunlight exposure; however, a hierarchical cluster analysis revealed that the members of this family were grouped into three distinct accumulation patterns, with malvidin anthocyanins and cyanidin-glucoside showing contrasting trends. The flavonol-glucosides, quercetin and kaempferol, exhibited a logarithmic response to SI, leading to improved cluster uniformity under high-light conditions. Comparing the within-cluster variability of metabolite accumulation highlighted the stability of sugars, flavan-3-ols, and cinnamic acid metabolites to SI, in contrast to the plasticity of flavonols. A correlation-based network analysis revealed that extended exposure to SI modified metabolic coordination, increasing the number of negative

  5. Vaccination against seasonal flu

    CERN Multimedia

    2015-01-01

    The Medical Service once again recommends you to get your annual flu vaccination for the year.   Vaccination is the most effective way of avoiding the illness and any serious consequences and protecting those around you. The flu can have especially serious consequences for people with chronic conditions (diabetes, cardio-vascular disease, etc.), pregnant women, infants, and people over 65 years of age. Remember, anyone working on the CERN site who wishes to be vaccinated against seasonal flu should go to the Infirmary (Building 57, ground floor) with their vaccine. The Medical Service will issue a prescription on the day of the vaccination for the purposes of reimbursement by UNIQA. NB: The Medical Service cannot provide this vaccination service for family members or retired members of the personnel. For more information: • The "Seasonal flu" flyer by the Medical Service • Recommendations of the Swiss Federal Office of Public...

  6. Vaccination against seasonal influenza

    CERN Multimedia

    DG Unit

    2009-01-01

    As every year, the Medical Service is taking part in the campaign to promote vaccination against seasonal influenza. Vaccination against seasonal influenza is especially recommended for people suffering from chronic lung, cardio-vascular or kidney conditions or diabetes, for those recovering from a serious illness or surgical operation and for everyone over the age of 65. The influenza virus is transmitted by air and contact with contaminated surfaces, hence the importance of washing hands regularly with soap and / or disinfection using a hydro-alcoholic solution. From the onset of symptoms (fever> 38°, chills, cough, muscle aches and / or joint pain, fatigue) you are strongly recommended to stay at home to avoid spreading the virus. In the present context of the influenza A (H1N1) pandemic, it is important to dissociate these two illnesses and emphasise that the two viruses and the vaccines used to combat them are quite different and that protection against one will not pr...

  7. An approach to quantify sources, seasonal change, and biogeochemical processes affecting metal loading in streams: Facilitating decisions for remediation of mine drainage

    Science.gov (United States)

    Kimball, B.A.; Runkel, R.L.; Walton-Day, K.

    2010-01-01

    Historical mining has left complex problems in catchments throughout the world. Land managers are faced with making cost-effective plans to remediate mine influences. Remediation plans are facilitated by spatial mass-loading profiles that indicate the locations of metal mass-loading, seasonal changes, and the extent of biogeochemical processes. Field-scale experiments during both low- and high-flow conditions and time-series data over diel cycles illustrate how this can be accomplished. A low-flow experiment provided spatially detailed loading profiles to indicate where loading occurred. For example, SO42 - was principally derived from sources upstream from the study reach, but three principal locations also were important for SO42 - loading within the reach. During high-flow conditions, Lagrangian sampling provided data to interpret seasonal changes and indicated locations where snowmelt runoff flushed metals to the stream. Comparison of metal concentrations between the low- and high-flow experiments indicated substantial increases in metal loading at high flow, but little change in metal concentrations, showing that toxicity at the most downstream sampling site was not substantially greater during snowmelt runoff. During high-flow conditions, a detailed temporal sampling at fixed sites indicated that Zn concentration more than doubled during the diel cycle. Monitoring programs must account for diel variation to provide meaningful results. Mass-loading studies during different flow conditions and detailed time-series over diel cycles provide useful scientific support for stream management decisions.

  8. Simulation of the Unexpected Photosynthetic Seasonality in Amazonian Evergreen Forests by Using an Improved Diffuse Fraction-Based Light Use Efficiency Model

    Science.gov (United States)

    Yan, Hao; Wang, Shao-Qiang; da Rocha, Humberto R.; Rap, Alexandru; Bonal, Damien; Butt, Nathalie; Coupe, Natalia Restrepo; Shugart, Herman H.

    2017-11-01

    Understanding the mechanism of photosynthetic seasonality in Amazonian evergreen forests is critical for its formulation in global climate and carbon cycle models. However, the control of the unexpected photosynthetic seasonality is highly uncertain. Here we use eddy-covariance data across a network of Amazonian research sites and a novel evapotranspiration (E) and two-leaf-photosynthesis-coupled model to investigate links between photosynthetic seasonality and climate factors on monthly scales. It reproduces the GPP seasonality (R2 = 0.45-0.69) with a root-mean-square error (RMSE) of 0.67-1.25 g C m-2 d-1 and a Bias of -0.03-1.04 g C m-2 d-1 for four evergreen forest sites. We find that the proportion of diffuse and direct sunlight governs the photosynthetic seasonality via their interaction with sunlit and shaded leaves, supported by a proof that canopy light use efficiency (LUE) has a strong linear relationship with the fraction of diffuse sunlight for Amazonian evergreen forests. In the transition from dry season to rainy season, incident total radiation (Q) decreased while LUE and diffuse fraction increased, which produced the large seasonal increase ( 34%) in GPP of evergreen forests. We conclude that diffuse radiation is an important environmental driver of the photosynthetic seasonality in tropical Amazon forests yet depending on light utilization by sunlit and shaded leaves. Besides, the GPP model simulates the precipitation-dominated GPP seasonality (R2 = 0.40-0.69) at pasture and savanna sites. These findings present an improved physiological method to relate light components with GPP in tropical Amazon.

  9. Summer season | Cafeteria closures

    CERN Multimedia

    2013-01-01

    Please note the following cafeteria closures over the summer season: Bldg. 54 closed from 29/07/2013 to 06/09/2013. Bldg. 13: closed from 13/07/2013 to 06/09/2013. Restaurant No. 2, table service (brasserie and restaurant): closed from 01/08/2013 to 06/09/2013. Bldg. 864: closed from 29/07/2013 to 06/09/2013. Bldg. 865: closed from 29/07/2013 to 06/09/2013.

  10. Quantification of the impact of precipitation spatial distribution uncertainty on predictive uncertainty of a snowmelt runoff model

    Science.gov (United States)

    Jacquin, A. P.

    2012-04-01

    This study is intended to quantify the impact of uncertainty about precipitation spatial distribution on predictive uncertainty of a snowmelt runoff model. This problem is especially relevant in mountain catchments with a sparse precipitation observation network and relative short precipitation records. The model analysed is a conceptual watershed model operating at a monthly time step. The model divides the catchment into five elevation zones, where the fifth zone corresponds to the catchment's glaciers. Precipitation amounts at each elevation zone i are estimated as the product between observed precipitation at a station and a precipitation factor FPi. If other precipitation data are not available, these precipitation factors must be adjusted during the calibration process and are thus seen as parameters of the model. In the case of the fifth zone, glaciers are seen as an inexhaustible source of water that melts when the snow cover is depleted.The catchment case study is Aconcagua River at Chacabuquito, located in the Andean region of Central Chile. The model's predictive uncertainty is measured in terms of the output variance of the mean squared error of the Box-Cox transformed discharge, the relative volumetric error, and the weighted average of snow water equivalent in the elevation zones at the end of the simulation period. Sobol's variance decomposition (SVD) method is used for assessing the impact of precipitation spatial distribution, represented by the precipitation factors FPi, on the models' predictive uncertainty. In the SVD method, the first order effect of a parameter (or group of parameters) indicates the fraction of predictive uncertainty that could be reduced if the true value of this parameter (or group) was known. Similarly, the total effect of a parameter (or group) measures the fraction of predictive uncertainty that would remain if the true value of this parameter (or group) was unknown, but all the remaining model parameters could be fixed

  11. Direct contamination - seasonality

    International Nuclear Information System (INIS)

    Aarkrog, A.

    1994-01-01

    Direct contamination is the primary pathway to terrestrial vegetation in the first period after an activity release to the atmosphere. All radionuclides are able to be transferred via this pathway. Deposition, interception and retention are the three processes involved in direct contamination of crops. Wet deposition is more important than dry deposition in temperature regions. Resuspension and rainsplash both belong to secondary direct deposition and became evident for e.g. radiocaesium after the Chernobyl accident. Seasonality is the varying response to radioactive contamination of crops according to the time of the year when the contamination occurs. Shortlived radionuclides (as 131 I) and those that mainly enter the foodchain by direct contamination (e.g. 137 Cs) are especially important in this connection. In particular, the contamination of cereal crops is influenced by seasonality. As a result of seasonality the impact of the Chernobyl accident on the radioactive contamination of human diet was for the same deposition density higher in southern than in northern Europe. (orig.)

  12. Vaccination against seasonal influenza

    CERN Multimedia

    GS Department

    2010-01-01

    This year, as usual, the Medical Service is helping to promote vaccination against seasonal influenza. Vaccination against seasonal flu is especially recommended for anyone who suffers from chronic pulmonary, cardio-vascular or kidney disease or diabetes, is recovering from a serious illness or major surgery, or is over 65 years of age. The flu virus is transmitted through the air and through contact with contaminated surfaces, so frequent hand-washing with soap and/or an antiseptic hand wash is of great importance. As soon as the first symptoms appear (fever above 38°, shivering, coughing, muscle and/or joint pains, generalised weakness), you are strongly recommended to stay at home to avoid spreading the virus. Anyone working on the CERN site who wishes to be vaccinated against seasonal flu should go to the Infirmary (Building 57, ground floor), with their dose of vaccine. The Medical Service will issue a prescription on the day of the vaccination for the purposes of reimbursement through UNIQA...

  13. Flublok Seasonal Influenza (Flu) Vaccination

    Science.gov (United States)

    ... type="submit" value="Submit" /> Archived Flu Emails Influenza Types Seasonal Avian Swine Variant Pandemic Other Flublok Seasonal Influenza (Flu) Vaccine Questions & Answers Language: English (US) Español ...

  14. Genome-Wide Transcriptional Profiles of the Berry Skin of Two Red Grape Cultivars (Vitis vinifera) in Which Anthocyanin Synthesis Is Sunlight-Dependent or -Independent

    Science.gov (United States)

    Guan, Le; Xin, Hai-Ping; Li, Ji-Hu; Li, Shao-Hua

    2014-01-01

    Global gene expression was analyzed in the berry skin of two red grape cultivars, which can (‘Jingyan’) or cannot (‘Jingxiu’) synthesize anthocyanins after sunlight exclusion from fruit set until maturity. Gene transcripts responding to sunlight exclusion in ‘Jingyan’ were less complex than in ‘Jingxiu’; 528 genes were induced and 383 repressed in the former, whereas 2655 genes were induced and 205 suppressed in ‘Jingxiu’. They were regulated either in the same or opposing manner in the two cultivars, or in only one cultivar. In addition to VvUFGT and VvMYBA1, some candidate genes (e.g. AOMT, GST, and ANP) were identified which are probably involved in the differential responses of ‘Jingxiu’ and ‘Jingyan’ to sunlight exclusion. In addition, 26 MYB, 14 bHLH and 23 WD40 genes responded differently to sunlight exclusion in the two cultivars. Interestingly, all of the 189 genes classified as being relevant to ubiquitin-dependent protein degradation were down-regulated by sunlight exclusion in ‘Jingxiu’, but the majority (162) remained unchanged in ‘Jingyan’ berry skin. It would be of interest to determine the precise role of the ubiquitin pathway following sunlight exclusion, particularly the role of COP9 signalosome, cullins, RING-Box 1, and COP1-interacting proteins. Only a few genes in the light signal system were found to be regulated by sunlight exclusion in either or both cultivars. This study provides a valuable overview of the transcriptome changes and gives insight into the genetic background that may be responsible for sunlight-dependent versus -independent anthocyanin biosynthesis in berry skin. PMID:25158067

  15. NEW SEASON NEW HOPES: OFF-SEASON OPTIMISM

    Directory of Open Access Journals (Sweden)

    Oguz Ersan

    2017-12-01

    Full Text Available While literature on the relation between on-field sports performance and stock returns is ample, there is very limited evidence on off-season stage. Constituting around 3 months, off-seasons do not only occupy a significant part of the year but also represent totally different characteristics than on-seasons. They lack the periodic, unambiguous news events in on-seasons (match results, instead they are associated with highly uncertain transfer news and rumors. We show that this distinction has several impacts on the stock market performances of soccer clubs. Most notably, off-seasons generate substantially higher (excess returns. After controlling for other variables, the estimated effect of off-season periods is as high as 38.75%, annually. In line with several seminal studies, we link this fact to increased optimism and betting behavior through uncertain periods; and periods prior to the start of a new calendar (in our case, new season. For all of the examined 7 clubs (3 from Italy and 4 from Turkey, mean excess returns over the market are positive (negative in off-seasons (on-seasons. On-seasons are associated with increased trading activity due to more frequent news. Stocks of Italian clubs are evidently more volatile through off-seasons while volatility results for the stocks of Turkish clubs are not consistent.

  16. Seca da semente de café ao sol Effect of sunlight on coffee seed viability

    Directory of Open Access Journals (Sweden)

    Oswaldo Bacchi

    1955-01-01

    Full Text Available O presente trabalho diz respeito a estudos realizados com o objetivo de observar a influência da luz solar sôbre a capacidade germinativa da semente despolpada de café e verificar, portanto, a possibilidade de se efetuar a seca desta semente exclusivamente ao sol. Além de um ensaio preliminar, foram efetuados mais outros dois, compreendendo, ao todo, duas secas ao sol, duas em um secador a baixa temperatura (±28°C, uma a sombra e uma em um secador a alta temperatura (±40°C. Pelas correlações entre as porcentagens de germinação e de umidade, que foram estabelecidas após diferentes períodos de secagem, foram tiradas as duas seguintes conclusões, que são as principais com relação ao objetivo dêstes ensaios : 1 Os raios solares são prejudiciais à capacidade germinativa da semente de café; sua nocividade acha-se, porém, intimamente ligada ao teor de umidade na semente. 2 À vista da conclusão acima, verifica-se que a semente despolpada de café e, muito provavelmente, também a não despolpada, podem ser perfeitamente sêcas a pleno sol sem que haja prejuízo para sua vitalidade, uma vez que sejam recolhidas antes que o seu teor de umidade caia abaixo do ponto crítico de 8% - 9%.In this paper the author deals with the question related to the coffee seed drying, with special attention to the effect of the sun radiations on seed viability. Based on the results obtained, the following conclusions were drawn : (a The sun rays have no specific influence on the viability of hulled coffee seed ; their effect is indirect and related to loss of moisture by the seed. (b Coffee seed can be dried in the sunlight without loss of viability if the water content does not drop under 8% to 9%. Below this critical level seed germination falls rapidly. (c The moisture content of coffee seed dried „in the sun may fall to about 7% in a short time with the consequent injury to viability. (d Under most conditions in the state of São Paulo

  17. Dietary intakes of expeditioners during prolonged sunlight deprivation in polar enviroments do not support bone health

    Directory of Open Access Journals (Sweden)

    Sandra Iuliano

    2015-08-01

    Full Text Available Background: Early Antarctic expeditions were plagued by nutrient deficiencies, due to lack of fresh food and reliance on preserved foods. Modern Antarctic expeditioners also require provisions to be shipped in, but improved knowledge and storage options ensure foods are nutritionally sound. Despite this, nutritional imbalances are observed. Objectives: To determine the adequacy of dietary intake of Antarctic expeditioners, with reference to bone health. Design: Dietary intake was determined on 225 adults (mean age 42±11 years, 16% female during 12-month deployments at Australian Antarctic stations from 2004 to 2010, using weighed 3-day food records. Nutrient intake was analysed using FoodWorks. Foods were divided into the 5 food groups according to the Australian Guide to Healthy Eating. Results: Men consumed below the recommended levels [recommended daily intake (RDI/adequate intakes (AI] of calcium (79±42% of RDI, p<0.001, magnesium (83±34% of RDI, p<0.001, potassium (86±29% of AI, p<0.001 and fibre (75±30% of AI, p<0.001, and above the upper limit (UL for sodium (125±48% of UL p<0.001, whereas women consumed below the recommended levels of calcium (68±21% of RDI, p<0.001 and iron (73±37% of RDI, p<0.001. Vitamin D intake is not substantial (<150 IU/d. Men consumed more alcohol than women (18±24 g/d vs. 10±13 g/d, p<0.05, nearer the guideline of ≤20 g/d. Men and women consumed approximately 1 serving of dairy food per day, and 3 of 5 recommended vegetable servings. Discretionary foods were consumed in excess of recommended. Conclusions: Improving consumption of calcium-rich (dairy foods better supports bone health during sunlight deprivation. Increasing vegetable intake to recommended levels will increase fibre, potassium and magnesium intakes. The challenge is the logistics of providing these foods throughout the year.

  18. Seasonal Snowpack Dynamics and Runoff in a Maritime Forested Basin, Niigata, Japan

    Science.gov (United States)

    Whitaker, A. C.; Sugiyama, H.

    2005-12-01

    Seasonal snowpack dynamics are described through field measurements under contrasting canopy conditions for a mountainous catchment in the Japan Sea region. Microclimatic data, snow accumulation, albedo and lysimeter runoff is given through three complete winter seasons 2002-05 in: (1) mature cedar stand, (2) larch stand, and (3) regenerating cedar stand or opening. The accumulation and melt of seasonal snowpack strongly influences streamflow runoff during December to May, including winter base-flow, mid-winter melt, rain-on-snow, and diurnal peaks driven by radiation melt in spring. Lysimeter runoff at all sites is characterised by constant ground melt of 0.8-1.0 mm/day. Rapid response to mid-winter melt or rainfall shows that the snowpack remains in a ripe or near-ripe condition throughout the snowcover season. Hourly and daily lysimeter discharge was greatest during rain-on-snow with the majority of runoff due to rainfall passing through the snowpack as opposed to snowmelt. For both rain-on-snow and radiation melt events lysimeter discharge was generally greatest at the open site, although there were exceptions such as during interception melt events. During radiation melt instantaneous discharge was up to 4.0 times greater in the opening compared to the mature cedar, and 48-hour discharge was up to 2.5 times greater. Perhaps characteristic of maritime climates, forest interception melt is shown to be important in addition to sublimation in reducing snow accumulation beneath dense canopies. While sublimation represents a loss from the catchment water balance, interception melt percolates through the snowpack and contributes to soil moisture during the winter season. Strong differences in microclimate and snowpack albedo persisted between cedar, larch and open sites, and it is suggested further work is needed to account for this in hydrological simulation models.

  19. Monitoring snowmelt and solute transport at Oslo airport by combining time-lapse electrical resistivity, soil water sampling and tensiometer measurements

    Science.gov (United States)

    Bloem, E.; French, H. K.

    2013-12-01

    Monitoring contaminant transport at contaminated sites requires optimization of the configuration of a limited number of samplings points combined with heterogeneous flow and preferential flowpaths. Especially monitoring processes in the unsaturated zone is a major challenge due to the limited volume monitored by for example suction cups and their risk to clog in a highly active degradation zone. To make progress on soil contamination assessment and site characterization there is a strong need to integrate field-sale extensively instrumented tools, with non-invasive (geophysical) methods which provide spatially integrated measurements also in the unsaturated zone. Examples of sites that might require monitoring activities in the unsaturated zone are airports with winter frost where large quantities of de-icing chemicals are used each winter; salt and contaminant infiltration along roads; constructed infiltration systems for treatment of sewerage or landfill seepage. Electrical resistivity methods have proved to be useful as an indirect measurement of subsurface properties and processes at the field-scale. The non-uniqueness of the interpretation techniques can be reduced by constraining the inversion through the addition of independent geophysical measurements along the same profile. Or interpretation and understanding of geophysical images can be improved by the combination with classical measurements of soil physical properties, soil suction, contaminant concentration and temperatures. In our experiment, at the research field station at Gardermoen, Oslo airport, we applied a degradable de-icing chemical and an inactive tracer to the snow cover prior to snowmelt. To study the solute transport processes in the unsaturated zone time-lapse cross borehole electrical resistivity tomography (ERT) measurements were conducted at the same time as soil water samples were extracted at multiple depths with suction cups. Measurements of soil temperature, and soil tension were

  20. Laminae development in opal-A precipitates associated with seasonal growth of the form-genus Calothrix (Cyanobacteria), Rehai geothermal area, Tengchong, Yunnan Province, China

    Science.gov (United States)

    Jones, Brian; Peng, Xiaotong

    2015-04-01

    The western discharge apron at Meinuquan (Rehai geothermal area, Yunnan Province, China), which incorporates the upper terrace, terrace front, and lower terrace, is covered with laminated opal-A precipitates that have formed from the spring waters that flow across its surface. Laminae are formed of silicified Calothrix mats or featureless opal-A that contains no microbes, scattered spherical and rod-shaped microbes, and/or rare Calothrix. Rapid silicification of the Calothrix led to preservation of their basal heterocysts, vegetative cells, trichomes, tapering filaments, and laminated and splayed sheaths. The Calothrix mats grew during the dry season when there was maximum sunlight because of low cloud cover. During this time, the mats grew under stable conditions because the water that flowed across the discharge apron was sourced from the springs, and temperature and water geochemistry was more or less constant. Growth of the Calothrix mats decreased during the wet season (April to late September) when sunlight is reduced due to the extensive cloud cover associated with the monsoonal rains. During the wet season, water flowing over the discharge apron is a mixture of rainwater, runoff from the surrounding hillsides, and spring water. Such variable flow conditions, water temperatures, and water geochemistry curtailed microbe growth and impacted silica precipitation. The precipitates at Meinuquan are like those associated with some Icelandic hot springs. Although growth of Calothrix is controlled by sunlight in both settings, the periods of maximum sunlight in China (October-March) and Iceland (June-August) are at different times of the year because of their geographic locations.

  1. Music season coming soon

    CERN Multimedia

    CERN Bulletin in collaboration with Julio Rosenfeld

    2012-01-01

    On 16 June, CERN’s music season will open with Music on the Lawn. The event is the CERN Music Club’s contribution to the Fete de la Musique and will take place on the terrace of Restaurant 1 from 2 p.m. to 8 p.m. The Hardronic Festival, CERN’s long-running rock festival, will be held on the evenings of 20 and 21 July in Prévessin, on the terrace behind Restaurant 3. If you would like to help with the organisation, please contact the Music Club by e-mail: music.club@cern.ch.   The Canettes Blues Band during the 2011 Hardronic Festival. (© Christoph Balle, 2010). Summer is coming, and along with it comes the music season. CERN will be hosting its two annual rock music concerts: Music on the Lawn and the Hardronic Festival. The two events are organised by the CERN Music Club, which has been sharing the enjoyment of good music with its numerous fans for many years. “Music on the Lawn was originally created so that the members of the Mus...

  2. Flu season and trehalose

    Directory of Open Access Journals (Sweden)

    Robbins RA

    2018-01-01

    Full Text Available Most of us who are practicing medicine know that we are in a very active flu season. This was brought home to me when last week trying to admit a patient to the hospital from the office. She was a bone marrow transplant patient who had severe diarrhea and dehydration probably secondary to C. difficile. Hospital admissions said the patient had to be sent to the Emergency Room because the hospital was full due to the flu epidemic. Nationwide there has been a dramatic increase in the number of hospitalizations due to influenza over the past week from 13.7 to 22.7 per 100,000 (1. Influenza A(H3N2 has been the most common form of influenza reported this season. These viruses are often linked to more severe illness, especially in children and people age 65 years and older. Fortunately, the CDC also says that the flu cases may be peaking. However, at ...

  3. Vaccination against seasonal influenza

    CERN Multimedia

    SC Unit

    2009-01-01

    As every year, the Medical Service is taking part in the campaign to promote vaccination against seasonal influenza. Vaccination against seasonal influenza is especially recommended for people suffering from chronic lung, cardio-vascular or kidney conditions or diabetes, for those recovering from a serious illness or surgical operation and for everyone over the age of 65. The influenza virus is transmitted by air and contact with contaminated surfaces, hence the importance of washing hands regularly with soap and / or disinfection using a hydro-alcoholic solution. From the onset of symptoms (fever> 38°, chills, cough, muscle aches and / or joint pain, fatigue) you are strongly recommended to stay at home to avoid spreading the virus. In the present context of the influenza A (H1N1) pandemic, it is important to dissociate these two illnesses and emphasise that the two viruses and the vaccines used to combat them are quite different and that protection against one will not provide protection against the...

  4. Using Microporous Polytetrafluoroethylene Thin Sheets as a Flexible Solar Diffuser to Minimize Sunlight Glint to Cameras in Space

    Science.gov (United States)

    Choi, Michael K.

    2016-01-01

    An innovative design of using microporous PTFE thin sheets as a solar diffuser for MLI blankets or mechanical structure has been developed. It minimizes sunlight or stray-light glint to cameras when it is incident on these components in space. A microporous black PTFE thin sheet solar diffuser has been qualified for flight at NASA GSFC and installed to the TAGSAM arm MLI, OCAMS PolyCam sunshade MLI and SamCam motor riser MLI in the NASA OSIRIS-REx mission to meet the SamCam camera BRDF requirement.

  5. Aromatic/heterocyclic amino acids and the simulated sunlight-ultraviolet inactivation of the Heliothis/Helicoverpa baculovirus

    International Nuclear Information System (INIS)

    Ignoffo, C.M.; Garcia, C.

    1995-01-01

    Tryptophan, of five aromatic/heterocyclic amino acids (tyrosine, phenylalanine, proline, histidine) provided significant protection of the Heliothis baculovirus (HzSNPV) from inactivation by simulated ultraviolet (SUV). Fifty percent of SUV protection of HzSNPV with tryptophan or tyrosine was obtained at 0.03 mg/ml and 0.5 mg/ml, respectively. Rates as high as 100.0 mg/ml of phenylalanine, histidine, or proline provided <50% protection. The extent of tryptophan protection was correlated with its absorption in the sunlight UV-B spectra. 16 refs., 2 tabs

  6. Effect of exposure to sunlight and phosphorus-limitation on bacterial degradation of coloured dissolved organic matter (CDOM) in freshwater

    DEFF Research Database (Denmark)

    Kragh, Theis; Søndergaard, Morten; Tranvik, Lars

    2008-01-01

    This study reports on the interacting effect of photochemical conditioning of dissolved organic matter and inorganic phosphorus on the metabolic activity of bacteria in freshwater. Batch cultures with lake-water bacteria and dissolved organic carbon (DOC) extracted from a humic boreal river were...... arranged in an experimental matrix of three levels of exposure to simulated sunlight and three levels of phosphorus concentration. We measured an increase in bacterial biomass, a decrease in DOC and bacterial respiration as CO(2) production and O(2) consumption over 450 h. These measurements were used...

  7. Using microporous polytetrafluoroethylene thin sheets as a flexible solar diffuser to minimize sunlight glint to cameras in space

    Science.gov (United States)

    Choi, Michael K.

    2016-09-01

    An innovative design of using microporous PTFE thin sheets as a solar diffuser for MLI blankets or mechanical structure has been developed. It minimizes sunlight or stray-light glint to cameras when it is incident on these components in space. A microporous black PTFE thin sheet solar diffuser has been qualified for flight at NASA GSFC and installed to the TAGSAM arm MLI, OCAMS PolyCam sunshade MLI and SamCam motor riser MLI in the NASA OSIRIS-REx mission to meet the SamCam camera BRDF requirement.

  8. Knowledge of vitamin D and perceptions and attitudes toward sunlight among Chinese middle-aged and elderly women: a population survey in Hong Kong

    Directory of Open Access Journals (Sweden)

    Lee Ka-Kui

    2006-09-01

    Full Text Available Abstract Background Physical and biological risk factors for vitamin D inadequacy are known; however, cultural- and population-specific behaviours and attitudes that influence these risk factors, particularly among Asian people, are less well documented. To understand more about prevailing attitudes and behaviour toward sunlight and knowledge of vitamin D among a population at greater risk of impaired vitamin D status, poor bone health and osteoporosis, we conducted a telephone interview survey of 547 middle-aged and elderly Chinese women living in Hong Kong. Methods All telephone interviews were conducted using the Computer Assisted Telephone Technique and target respondents were selected by random sampling. Interviews were conducted in Cantonese and eighteen main questions were asked pertaining to personal characteristics, perceptions, attitudes and behaviour toward sunlight, and knowledge about vitamin D. Results The survey results showed that 62.3% (n = 341 did not like going in the sun and 66.7% of respondents spent an average of 6–10 hours indoors, between 6:30 am and 7:00 pm, during weekdays. However, 58% of people thought that they had enough exposure to sunlight. The majority had heard of vitamin D, but knowledge about the role and sources of vitamin D was low. Among those who knew that sunlight was a source of vitamin D, the majority spent less than 1 h in the sun in the past week (76.4% vs 23.6%, 1 h in the sun in the past week, chi-square p Conclusion The survey revealed considerable ignorance and confusion about the role of sunlight in vitamin D production, and the function and sources of vitamin D. Attitudes and behaviour toward sunlight were largely negative and many took measures to avoid sunlight, particularly among younger (middle-aged women who had good awareness of vitamin D.

  9. Patterns and timing of sunlight exposure and risk of basal cell and squamous cell carcinomas of the skin – a case–control study

    Directory of Open Access Journals (Sweden)

    Iannacone Michelle R

    2012-09-01

    Full Text Available Abstract Background Non-melanoma skin cancer (NMSC, comprised of basal (BCC and squamous (SCC cell carcinomas, is the most common cancer in Caucasians. Ultraviolet radiation (UVR exposure is the most important environmental risk factor for NMSC. However, the precise relationship between UVR and the risk of NMSC is complex, and the relationship may differ by skin cancer type. Methods A case–control study was conducted among Florida residents to investigate measures of patterns (intermittent vs. continuous and timing (childhood vs. adulthood of sunlight exposure in BCC and SCC. Participants included 218 BCC and 169 SCC cases recruited from a university dermatology clinic and 316 controls with no history of skin or other cancers. Results A history of blistering sunburn (a measure of intermittent sunlight exposure was associated with both BCC (OR = 1.96, 95% CI = 1.27-3.03 and SCC (OR = 2.02, 95% CI = 1.22-3.33. Additionally, having a job in the sun for ≥3 months for 10 years or longer (a measure of continuous sunlight exposure was also associated with both BCC and SCC in our study population. With the exception of younger age at first blistering sunburn, measures of younger age at sunlight exposure tended to be associated with SCC, but not BCC risk. Conclusions Results from the current study suggest that sunlight exposure is associated with both BCC and SCC risk regardless of the pattern in which the exposure was received (i.e. intermittent vs. continuous. The data also suggest that sunlight exposure at a younger age may be more important for SCC but not BCC, however additional studies are needed to further characterize sunlight exposure-response relationships in different types of NMSC.

  10. Patterns and timing of sunlight exposure and risk of basal cell and squamous cell carcinomas of the skin – a case–control study

    International Nuclear Information System (INIS)

    Iannacone, Michelle R; Fenske, Neil A; Rollison, Dana E; Wang, Wei; Stockwell, Heather G; O’Rourke, Kathleen; Giuliano, Anna R; Sondak, Vernon K; Messina, Jane L; Roetzheim, Richard G; Cherpelis, Basil S

    2012-01-01

    Non-melanoma skin cancer (NMSC), comprised of basal (BCC) and squamous (SCC) cell carcinomas, is the most common cancer in Caucasians. Ultraviolet radiation (UVR) exposure is the most important environmental risk factor for NMSC. However, the precise relationship between UVR and the risk of NMSC is complex, and the relationship may differ by skin cancer type. A case–control study was conducted among Florida residents to investigate measures of patterns (intermittent vs. continuous) and timing (childhood vs. adulthood) of sunlight exposure in BCC and SCC. Participants included 218 BCC and 169 SCC cases recruited from a university dermatology clinic and 316 controls with no history of skin or other cancers. A history of blistering sunburn (a measure of intermittent sunlight exposure) was associated with both BCC (OR = 1.96, 95% CI = 1.27-3.03) and SCC (OR = 2.02, 95% CI = 1.22-3.33). Additionally, having a job in the sun for ≥3 months for 10 years or longer (a measure of continuous sunlight exposure) was also associated with both BCC and SCC in our study population. With the exception of younger age at first blistering sunburn, measures of younger age at sunlight exposure tended to be associated with SCC, but not BCC risk. Results from the current study suggest that sunlight exposure is associated with both BCC and SCC risk regardless of the pattern in which the exposure was received (i.e. intermittent vs. continuous). The data also suggest that sunlight exposure at a younger age may be more important for SCC but not BCC, however additional studies are needed to further characterize sunlight exposure-response relationships in different types of NMSC

  11. Seasonal and inter-annual variability of aerosol optical properties during 2005-2010 over Red Mountain Pass and Impact on the Snow Cover of the San Juan Mountains

    Science.gov (United States)

    Singh, R. P.; Gautam, R.; Painter, T. H.

    2011-12-01

    Growing body of evidence suggests the significant role of aerosol solar absorption in accelerated seasonal snowmelt in the cryosphere and elevated mountain regions via snow contamination and radiative warming processes. Characterization of aerosol optical properties over seasonal snow cover and snowpacks is therefore important towards the better understanding of aerosol radiative effects and associated impact on snow albedo. In this study, we present seasonal variations in column-integrated aerosol optical properties retrieved from AERONET sunphotometer measurements (2005-2010) at Red Mountain Pass (37.90° N, 107.72° W, 3368 msl) in the San Juan Mountains, in the vicinity of the North American Great Basin and Colorado Plateau deserts. The aerosol optical depth (AOD) measured at 500nm is generally low (pollutant transport. In addition, the possibility of the observed increased coarse-mode influence associated with mineral dust influx cannot be ruled out, due to westerly-airmass driven transport from arid/desert regions as suggested by backward trajectory simulations. A meteorological coupling is also found in the summer season between AOD and column water vapor retrieved from AERONET with co-occurring enhanced water vapor and AOD. Based on column measurements, it is difficult to ascertain the aerosol composition, however, the summer-time enhanced aerosol loading as presented here is consistent with the increased dust deposition in the San Juan mountain snow cover as reported in recent studies. In summary, this study is expected to better understand the seasonal and inter-annual aerosol column variations and is an attempt to provide an insight into the effects of aerosol solar absorption on accelerated seasonal snowmelt in the San Juan mountains.

  12. Snow cover volumes dynamic monitoring during melting season using high topographic accuracy approach for a Lebanese high plateau witness sinkhole

    Science.gov (United States)

    Abou Chakra, Charbel; Somma, Janine; Elali, Taha; Drapeau, Laurent

    2017-04-01

    Climate change and its negative impact on water resource is well described. For countries like Lebanon, undergoing major population's rise and already decreasing precipitations issues, effective water resources management is crucial. Their continuous and systematic monitoring overs long period of time is therefore an important activity to investigate drought risk scenarios for the Lebanese territory. Snow cover on Lebanese mountains is the most important water resources reserve. Consequently, systematic observation of snow cover dynamic plays a major role in order to support hydrologic research with accurate data on snow cover volumes over the melting season. For the last 20 years few studies have been conducted for Lebanese snow cover. They were focusing on estimating the snow cover surface using remote sensing and terrestrial measurement without obtaining accurate maps for the sampled locations. Indeed, estimations of both snow cover area and volumes are difficult due to snow accumulation very high variability and Lebanese mountains chains slopes topographic heterogeneity. Therefore, the snow cover relief measurement in its three-dimensional aspect and its Digital Elevation Model computation is essential to estimate snow cover volume. Despite the need to cover the all lebanese territory, we favored experimental terrestrial topographic site approaches due to high resolution satellite imagery cost, its limited accessibility and its acquisition restrictions. It is also most challenging to modelise snow cover at national scale. We therefore, selected a representative witness sinkhole located at Ouyoun el Siman to undertake systematic and continuous observations based on topographic approach using a total station. After four years of continuous observations, we acknowledged the relation between snow melt rate, date of total melting and neighboring springs discharges. Consequently, we are able to forecast, early in the season, dates of total snowmelt and springs low

  13. Seasonal soybean crop reflectance

    Science.gov (United States)

    Lemaster, E. W. (Principal Investigator); Chance, J. E.

    1983-01-01

    Data are presented from field measurements of 1980 including 5 acquisitions of handheld radiometer reflectance measurements, 7 complete sets of parameters for implementing the Suits mode, and other biophysical parameters to characterize the soybean canopy. LANDSAT calculations on the simulated Brazilian soybean reflectance are included along with data collected during the summer and fall on 1981 on soybean single leaf optical parameters for three irrigation treatments. Tests of the Suits vegetative canopy reflectance model for the full hemisphere of observer directions as well as the nadir direction show moderate agreement for the visible channels of the MSS and poor agreement in the near infrared channel. Temporal changes in the spectral characteristics of the single leaves were seen to occur as a function of maturity which demonstrates that the absorptance of a soybean single leaf is more a function of thetransmittancee characteristics than the seasonally consistent single leaf reflectance.

  14. Season-ahead streamflow forecast informed tax strategies for semi-arid water rights markets

    Science.gov (United States)

    Delorit, J. D.; Block, P. J.

    2016-12-01

    In many semi-arid regions multisectoral demands stress available water supplies. The Elqui River valley of north central Chile, which draws on limited capacity reservoirs supplied largely by annually variable snowmelt, is one of these cases. This variability forces water managers to develop demand-based allocation strategies which have typically resulted in water right volume reductions, applied equally per right. Compounding this issue is often deferred or delayed infrastructure investments, which has been linked Chile's Coasian approach to water markets, under which rights holders do not pay direct procurement costs, non-use fees, nor taxes. Here we build upon our previous research using forecasts of likely water rights reductions, informed by season-ahead prediction models of October-January (austral growing season) streamflow, to construct annual, forecast-sensitive, per right tax. We believe this tax, to be borne by right holders, will improve the beneficial use of water resources by stimulating water rights trading and improving system efficiency by generating funds for infrastructure investment, thereby reducing free-ridership and conflict between rights holders. Research outputs will include sectoral per right tax assessments, tax revenue generation, Elqui River valley economic output, and water rights trading activity.

  15. Sunlight-driven eco-friendly smart curtain based on infrared responsive graphene oxide-polymer photoactuators.

    Science.gov (United States)

    Leeladhar; Raturi, Parul; Singh, J P

    2018-02-27

    Photomechanical actuation is the conversion of light energy into mechanical energy through some smart materials. Infrared-responsive smart materials have become an emerging field of research due to easy availability and eco-friendly nature of their stimulus in the form of sunlight, which contains about 50% of near-infrared(nIR) making these materials useful at macro-scale photoactuator applications. Here, we demonstrate fabrication of highly versatile nIR triggered photoactuators based on graphene oxide/polycarbonate bilayers that offers fast, low-cost fabrication, large deflection, reversible actuation and wavelength-selective response. The photoactuators are realized by vacuum filtration of graphene oxide/water dispersion through polycarbonate membrane resulting graphene oxide/polymer bilayer structure. The photoactuation response was measured in the form of deflection from equilibrium position as a result of infrared-irradiation. The deflection is caused by the generated thermal stress at the interface of bilayers due to mismatch of thermal expansion coefficient as a results of nIR absorption by graphene oxide and subsequent temperature rise. A maximum deflection of 12 mm (circular-shaped structure with diameter 28 mm) with corresponding bending curvature of 0.33 cm -1 was shown by this photoactuator for illumination intensity of 106 mW/cm 2 . Few applications of these photoactuators such as sunlight-driven smart curtain, infrared actuated curtain and self-folding box are also demonstrated.

  16. Sunlight Triggers Cutaneous Lupus through a Colony Stimulating Factor-1 (CSF-1) Dependent Mechanism in MRL-Faslpr mice

    Science.gov (United States)

    Menke, Julia; Hsu, Mei-Yu; Byrne, Katelyn T.; Lucas, Julie A.; Rabacal, Whitney A.; Croker, Byron P.; Zong, Xiao-Hua; Stanley, E. Richard; Kelley, Vicki R.

    2008-01-01

    Sunlight (UVB) triggers cutaneous (CLE) and systemic lupus through an unknown mechanism. We tested the hypothesis that UVB triggers CLE through a CSF-1-dependent, macrophage (Mø) -mediated mechanism in MRL-Faslpr mice. By constructing mutant MRL-Faslpr strains expressing varying levels of CSF-1 (high, intermediate, none), and use of an ex-vivo gene transfer to deliver CSF-1 intra-dermally, we determined that CSF-1 induces CLE in lupus-susceptible, MRL-Faslpr mice, but not in lupus-resistant, BALB/c mice. Notably, UVB incites an increase in Mø, apoptosis in the skin and CLE in MRL-Faslpr, but not in CSF-1-deficient MRL-Faslpr mice. Furthermore, UVB did not induce CLE in BALB/c mice. Probing further, UVB stimulates CSF-1 expression by keratinocytes leading to recruitment and activation of Mø that, in turn, release mediators, which induce apoptosis in keratinocytes. Thus, sunlight triggers a CSF-1-dependent, Mø-mediated destructive inflammation in the skin leading to CLE in lupus-susceptible MRL-Faslpr, but not lupus-resistant BALB/c mice. Taken together, we envision CSF-1 as the “match” and lupus-susceptibility as the “tinder” leading to CLE. PMID:18981160

  17. Space Radar Image of Bebedauro, Brazil, seasonal

    Science.gov (United States)

    1994-01-01

    This is an X-band image showing seasonal changes at the hydrological test site of Bebedouro in Brazil. The image is centered at 9 degrees south latitude and 40.2 degrees west longitude. This image was acquired by the Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar (SIR-C/X-SAR) aboard the space shuttle Endeavour on April 10, 1994, during the first flight of the radar system, and on October 1, 1994, during the second mission. The swath width is approximately 16.5 kilometers (10.5 miles) wide. The image channels have the following color assignments: red represents data acquired on April 10; green represents data acquired on October 1; blue corresponds to the ratio of the two data sets. Agriculture plays an important economic and social role in Brazil. One of the major problems related to Brazilian agriculture is estimating the size of planting areas and their productivity. Due to cloud cover and the rainy season, which occurs from November through April, optical and infrared Earth observations are seldom used to survey the region. An additional goal of monitoring this region is to watch the floodplains of rivers like Rio Sao Francisco in order to determine suitable locations for additional agricultural fields. This area belongs to the semi-arid northeastern region of Brazil, where estimates have suggested that about 10 times more land could be used for agriculture, including some locations which could be used for irrigation projects. Monitoring of soil moisture during the important summer crop season is of high priority for the future development and productivity of this region. In April the area was covered with vegetation because of the moisture of the soil and only small differences could be seen in X-band data. In October the run-off channels of this hilly region stand out quite clearly because the greenish areas indicated much less soil moisture and water content in plants. Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar (SIR

  18. Sensitivities of dry season runoff to precipitation and temperature in southern Sierra Nevada streams

    Science.gov (United States)

    Safeeq, M.; Hunsaker, C. T.; Bales, R. C.

    2016-12-01

    In a mediterranean climate, dry season runoff sustains water supply and supports aquatic habitat and other ecosystems. Precipitation and temperature directly, by regulating recharge and evapotranspiration (ET), and indirectly, by regulating amount and timing of snowmelt, control the dry season runoff in the Sierra Nevada. Here, we explored relative impacts of precipitation and temperature variability on dry season runoff using path analysis. Specific objectives include: (i) to quantify the direct and indirect impacts of precipitation and temperature on 7-day average minimum flow (Qmin) and (ii) to explore the role of preceding year Qmin on fall season runoff (QF). We used daily runoff, air temperature, precipitation, and snow water equivalent (SWE) over 2004-2015 for the ten catchments in the Kings River Experimental Watersheds. For path analysis model of Qmin, we defined annual precipitation and temperature as exogenous variables and peak SWE, day of snow disappearance, and Qmin as endogenous variables. For QF, we defined current year fall precipitation and preceding year Qmin as exogenous variables and current year QF as an endogenous variable. Path analysis results for Qmin show precipitation as a dominant driver when compared to temperature, peak SWE, and day of snow disappearance. However, in half of the catchments that are mostly located at higher elevations the impact of temperature on Qmin was either comparable or exceeded that of precipitation. This relatively high sensitivity of Qmin to air temperature in high elevation catchments is consistent with the earlier findings of increased ET in proportion to warming. The direct effects of peak SWE and day of snow disappearance on Qmin were limited, and indirect effects of temperature and precipitation via peak SWE and day of snow disappearance were not significant. The preceding year Qmin and fall precipitation showed comparable impacts on QF, indicating that the storage in the preceding year modulates current

  19. Tundra shrub effects on growing season energy and carbon dioxide exchange

    Science.gov (United States)

    Lafleur, Peter M.; Humphreys, Elyn R.

    2018-05-01

    Increased shrub cover on the Arctic tundra is expected to impact ecosystem-atmosphere exchanges of carbon and energy resulting in feedbacks to the climate system, yet few direct measurements of shrub tundra-atmosphere exchanges are available to corroborate expectations. Here we present energy and carbon dioxide (CO2) fluxes measured using the eddy covariance technique over six growing seasons at three closely located tundra sites in Canada’s Low Arctic. The sites are dominated by the tundra shrub Betula glandulosa, but percent cover varies from 17%–60% and average shrub height ranges from 18–59 cm among sites. The site with greatest percent cover and height had greater snow accumulation, but contrary to some expectations, it had similar late-winter albedo and snow melt dates compared to the other two sites. Immediately after snowmelt latent heat fluxes increased more slowly at this site compared to the others. Yet by the end of the growing season there was little difference in cumulative latent heat flux among the sites, suggesting evapotranspiration was not increased with greater shrub cover. In contrast, lower albedo and less soil thaw contributed to greater summer sensible heat flux at the site with greatest shrub cover, resulting in greater total atmospheric heating. Net ecosystem exchange of CO2 revealed the potential for enhanced carbon cycling rates under greater shrub cover. Spring CO2 emissions were greatest at the site with greatest percent cover of shrubs, as was summer net uptake of CO2. The seasonal net sink for CO2 was ~2 times larger at the site with the greatest shrub cover compared to the site with the least shrub cover. These results largely agree with expectations that the growing season feedback to the atmosphere arising from shrub expansion in the Arctic has the potential to be negative for CO2 fluxes but positive for turbulent energy fluxes.

  20. Effect of grape bunch sunlight exposure and UV radiation on phenolics and volatile composition of Vitis vinifera L. cv. Pinot noir wine.

    Science.gov (United States)

    Song, Jianqiang; Smart, Richard; Wang, Hua; Dambergs, Bob; Sparrow, Angela; Qian, Michael C

    2015-04-15

    The effect of canopy leaf removal and ultraviolet (UV) on Pinot noir grape and wine composition was investigated in this study. Limited basal leaf removal in the fruit zone was conducted, compared to shaded bunches. The UV exposure was controlled using polycarbonate screens to block UV radiation, and acrylic screens to pass the UV. The results showed that bunch sunlight and UV exposure significantly increased the Brix and pH in the grape juice, and increased substantially wine colour density, anthocyanins, total pigment, total phenolics and tannin content. Bunch sunlight and UV exposure affected terpene alcohols, C13-norisprenoids and other volatile composition of the wine differently. Sunlight exposure and UV resulted in increase of nerol, geraniol and citronellol but not linalool. Sunlight exposure slightly increased the concentration of β-ionone, but the increase was not statistically significant for UV treatment. Neither sunlight nor UV treatment showed any impact on the concentration of β-damascenone. Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. Seasonal and Water Column Trends of the Relative Role of Nitrate and Nitrite as ·OH Sources in Surface Waters

    International Nuclear Information System (INIS)

    Vione, D.; Minero, C.; Maurino, V.; Pelizzetti, E.

    2007-01-01

    Based on literature data of sunlight spectrum, photolysis quantum yields, and absorption spectra, the relative role of nitrite and nitrate as ·OH sources in surface waters was assessed, and its dependence on the season and the depth of the water column studied. In the majority of surface water samples (river, lake and seawater) nitrite is expected to play a more important role as ·OH source compared to nitrate, in spite of the usually lower [NO 2 - ] values. Interestingly, under the hypothesis of a constant ratio of the concentrations of nitrate and nitrite (to be corrected later on for the actual concentration ratio in a given sample), the relative role of nitrite compared to nitrate would be minimum in summer, at noon, in the surface layer of natural waters. Any decrease in the sunlight intensity that can be experienced in the natural environment (different season than summer, water column absorption, time of the day other than the solar noon), with its associated influence on the sunlight spectrum, would increase the relative role of nitrite compared to nitrate

  2. Global Seasonality of Rotavirus Disease

    Science.gov (United States)

    Patel, Manish M.; Pitzer, Virginia; Alonso, Wladimir J.; Vera, David; Lopman, Ben; Tate, Jacqueline; Viboud, Cecile; Parashar, Umesh D.

    2012-01-01

    Background A substantial number of surveillance studies have documented rotavirus prevalence among children admitted for dehydrating diarrhea. We sought to establish global seasonal patterns of rotavirus disease before widespread vaccine introduction. Methods We reviewed studies of rotavirus detection in children with diarrhea published since 1995. We assessed potential relationships between seasonal prevalence and locality by plotting the average monthly proportion of diarrhea cases positive for rotavirus according to geography, country development, and latitude. We used linear regression to identify variables that were potentially associated with the seasonal intensity of rotavirus. Results Among a total of 99 studies representing all six geographical regions of the world, patterns of year-round disease were more evident in low- and low-middle income countries compared with upper-middle and high income countries where disease was more likely to be seasonal. The level of country development was a stronger predictor of strength of seasonality (P=0.001) than geographical location or climate. However, the observation of distinctly different seasonal patterns of rotavirus disease in some countries with similar geographical location, climate and level of development indicate that a single unifying explanation for variation in seasonality of rotavirus disease is unlikely. Conclusion While no unifying explanation emerged for varying rotavirus seasonality globally, the country income level was somewhat more predictive of the likelihood of having seasonal disease than other factors. Future evaluation of the effect of rotavirus vaccination on seasonal patterns of disease in different settings may help understand factors that drive the global seasonality of rotavirus disease. PMID:23190782

  3. A phytotron for plant stress research: how far can artificial lighting compare to natural sunlight?

    International Nuclear Information System (INIS)

    Thiel, S.; Döhring, T.; Köfferlein, M.; Kosak, A.; Martin, P.; Seidlitz, H.K.

    1996-01-01

    Plants have adapted very efficiently to their natural light habitat. Artificial plant illumination, therefore, requires careful design. Not only the quantity of radiation per area or volume (intensity) but also the spectral quality has to match seasonal and diurnal variations of natural global radiation as close as possible. The GSF Research Center has developed a phytotron system especially devoted to plant stress research, where these requirements are of particular importance. The phytotron consists of seven closed chambers (4 walk-in size chambers, two medium and one small sun simulator). Our contribution outlines the basic design of the lighting and presents spectral data. A good approximation of terrestrial global radiation is achieved if several commercially available lamp types are combined and adequate filters are applied to reject unwanted infrared and harmful ultraviolet radiation. A programmable switch control for the individual lamp banks allows a variation of both spectrum and intensity of the illumination. Spectroradiometric measurements show that the maximum level of illumination in the small and in the medium size chambers can compete both in spectral distribution and in intensity with outdoor global radiation for solar elevations up to 60°. The maximum light level available inside the large walk-in chambers reaches an irradiance corresponding to solar elevation of 50°. The UV-B: UV-A: PAR ratio, which mirrors the spectral balance of plant lighting, can be adjusted to values following the diurnal variation of natural global radiation.(author)

  4. Sunlight, iron and radicals to tackle the resistant leftovers of biotreated winery wastewater.

    Science.gov (United States)

    Ioannou, Lida; Velegraki, Theodora; Michael, Costas; Mantzavinos, Dionissios; Fatta-Kassinos, Despo

    2013-04-01

    Winery wastewater is characterized by high organic content consisting of alcohols, acids and recalcitrant high-molecular-weight compounds (e.g. polyphenols, tannins and lignins). So far, biological treatment constitutes the best available technology for such effluents that are characterized by high seasonal variability; however the strict legislation applied on the reclamation and reuse of wastewaters for irrigation purposes introduces the need for further treatment of the bioresistant fraction of winery effluents. In this context, the use of alternative treatment technologies, aiming to mineralize or transform refractory molecules into others which could be further biodegraded, is a matter of great concern. In this study, a winery effluent that had already been treated in a sequencing batch reactor was subjected to further purification by homogeneous and heterogeneous solar Fenton oxidation processes. The effect of various operating variables such as catalyst and oxidant concentration, initial pH, temperature and lamp power on the abatement of chemical oxygen demand (COD), dissolved organic carbon (DOC), color, total phenolics and ecotoxicity has been assessed in the homogeneous solar Fenton process. In addition, a comparative assessment between homogeneous and heterogeneous solar Fenton processes was performed. In the present study the homogeneous solar Fenton process has been demonstrated to be the most effective process, yielding COD, DOC and total phenolics removal of about 69%, 48% and 71% in 120 min of the photocatalytic treatment, respectively.

  5. Regional-seasonal weather forecasting

    Energy Technology Data Exchange (ETDEWEB)

    Abarbanel, H.; Foley, H.; MacDonald, G.; Rothaus, O.; Rudermann, M.; Vesecky, J.

    1980-08-01

    In the interest of allocating heating fuels optimally, the state-of-the-art for seasonal weather forecasting is reviewed. A model using an enormous data base of past weather data is contemplated to improve seasonal forecasts, but present skills do not make that practicable. 90 references. (PSB)

  6. Diagnosing the Role of Transpiration in the Transition from Dry to Wet Season Over the Amazon Using Satellite Observations

    Science.gov (United States)

    Wright, J. S.; Fu, R.; Yin, L.; Chae, J.

    2013-12-01

    Reanalysis data indicates that land surface evapotranspiration plays a key role in determining the timing of wet season onset over the Amazon. Here, we use satellite observations of water vapor and its stable isotopes, carbon dioxide, leaf area index, and precipitation together with reanalysis data to explore the importance of transpiration in initiating the transition from dry season to wet season over the Amazon. The growth of vegetation in this region is primarily limited by the availability of sunlight rather than the availability of soil moisture, so that the increase of solar radiation during the dry season coincides with dramatic increases in leaf area index within forested ecosystems. This period of plant growth is accompanied by uptake of carbon dioxide and enrichment of heavy isotopes in water vapor, particularly near the land surface. Reanalysis data indicate that this pre-wet season enrichment of HDO is accompanied by sharp increases in the surface latent heat flux, which eventually triggers sporadic moist convection. The transport of transpiration-enriched near-surface air by this convection causes a dramatic increase in free-tropospheric HDO in late August and September. September also marks transition points in the annual cycles of leaf area index (maximum) and carbon dioxide (minimum). The increase in convective activity during this period creates convergence, enhancing moisture transport into the region and initiating the wet season.

  7. Seasonal variations of ochreous precipitates in mine effluents in Finland

    International Nuclear Information System (INIS)

    Kumpulainen, Sirpa; Carlson, Liisa; Raeisaenen, Marja-Liisa

    2007-01-01

    Ochreous precipitate and water samples were collected from the surroundings of seven closed sulphide mines in Finland. In the Hammaslahti Zn-Cu-Au mine, Otravaara pyrite mine and Paroistenjaervi Cu-W-As mine, the collection was repeated in different seasons to study mineralogical and geochemical variations of precipitates. The sampling was done in 1999-2002 from the ditches and drainage ponds of the tailings and waste rock piles that are susceptible to seasonal changes. Mineralogy of the precipitates was evaluated by X-ray diffraction (XRD) and infrared spectroscopy (IR), and precipitate geochemistry was examined by selective extractions. Schwertmannite (Fe 8 O 8 (OH) 6 SO 4 ) was the most typical Fe hydroxide mineral found. Goethite was almost as common as schwertmannite, was often poorly ordered, and contained up to 10 wt.% of SO 4 . Goethite and schwertmannite were commonly found as mixtures, and they occurred in similar pH and SO 4 concentrations. Ferrihydrite (nominally Fe 5 HO 8 . 4H 2 O) was typically found in areas not influenced by acid mine drainage, and also in acid mine waters with high organic matter or As content. Jarosite (KFe 3 (SO 4 ) 2 (OH) 6 ) was found only in one site. In addition, some gypsum (CaSO 4 . 2H 2 O) and aluminous sulphate precipitates (presumably basaluminite, Al 4 (SO 4 )(OH) 10 . 5H 2 O) were identified. Selective extractions showed that acid extracts Fe tot /S tot -ratios of schwertmannite and goethite samples were similar, but the ratio of oxalate-extractable to total Fe, Fe ox /Fe tot , of goethite samples were lower than those of the schwertmannite samples. Only Al, Si and As were bound to precipitates in substantial amounts, up to several wt.%. In schwertmannites and goethites, Al, Cu, Co, Mn and Zn were mostly structural, substituting for Fe in an Fe oxyhydroxide structure or bound to surface adsorption sites in pores limited by diffusion. In ferrihydrites, heavy metals were also partly bound in adsorbed form dissolving in

  8. Photocatalysis and self-cleaning from g-C3N4 coated cotton fabrics under sunlight irradiation

    Science.gov (United States)

    Fan, Yunde; Zhou, Ji; Zhang, Jin; Lou, Yaqin; Huang, Zhenwu; Ye, Yong; Jia, Li; Tang, Bin

    2018-05-01

    Graphite-like carbon nitride (g-C3N4) nanosheets have been facilely assembled via electrostatic interaction onto cotton fabrics for achieving multi-functionalities. The surface morphologies, chemical composition and optical features of the g-C3N4-coated fabrics were characterized. The treated cotton fabrics exhibited remarkable photocatalytic degradation activity and superior self-cleaning performance. A complete degradation of Rhodamine B (RhB) and removal of stains were accomplished under simulated sunlight irradiation. More importantly, the modified fabrics can be reused in catalysis reactions with great durability. The practical treatment approach demonstrated from this work has great potential to be applied in textile industry for functional fabrics manufacture.

  9. Reconfigurable Charge Pump Circuit with Variable Pumping Frequency Scheme for Harvesting Solar Energy under Various Sunlight Intensities

    Directory of Open Access Journals (Sweden)

    Jeong Heon Kim

    2014-01-01

    Full Text Available We propose variable pumping frequency (VPF scheme which is merged with the previous reconfigurable charge pump (RCP circuit that can change its architecture according to a given sunlight condition. Here, merging the VPF scheme with the architecture reconfiguration can improve percentage output currents better by 21.4% and 22.4% than RCP circuit with the fixed pumping frequencies of 7 MHz and 15 MHz, respectively. Comparing the VPF scheme with real maximum power points (MPP, the VPF can deliver 91.9% of the maximum amount of output current to the load on average. In terms of the power and area overheads, the VPF scheme proposed in this paper consumes the power by 0.4% of the total power consumption and occupies the layout area by 1.61% of the total layout area.

  10. The influence of exposure to ultraviolet radiation in simulated sunlight on ascospores causing Black Sigatoka disease of banana and plantain

    Science.gov (United States)

    Parnell, Mark; Burt, P. J. A.; Wilson, Kate

    The influence of ultraviolet (UV) radiation in simulated natural sunlight on the viability of ascospores of Mycosphaerella fijiensis, the cause of Black Sigatoka disease in banana and plantain, has been investigated as part of a study to assess the windborne spread of this pathogen from mainland Central and South America into the Caribbean. Spores were killed following continuous exposure to UV radiation for periods of 6 h or over. This relatively short exposure time suggests that the distances over which viable spores can be transported will be determined not only by the speed of the wind but also the amount of cloud cover and the time off day that spore release occurs. On this basis, wind dispersal of viable spores over distances greater than a few hundred kilometres is unlikely. These conclusions are reinforced by an examination of historical reports of the arrival of the disease in previously uninfected areas of the Americas and Africa.

  11. A Kolmogorov-type competition model with multiple coexistence states and its applications to plant competition for sunlight

    Science.gov (United States)

    Just, Winfried; Nevai, Andrew L.

    2008-12-01

    It is demonstrated that a Kolmogorov-type competition model featuring species allocation and gain functions can possess multiple coexistence statesE Two examples are constructed: one in which the two competing species possess rectangular allocation functions but distinct gain functions, and the other in which one species has a rectangular allocation function, the second species has a bi-rectangular allocation function, and the two species share a common gain function. In both examples, it is shown that the species nullclines may intersect multiple times within the interior of the first quadrant, thus creating both locally stable and unstable equilibrium points. These results have important applications in the study of plant competition for sunlight, in which the allocation functions describe the vertical placement of leaves for two competing species, and the gain functions represent rates of photosynthesis performed by leaves at different heights when shaded by overlying leaves belonging to either species.

  12. Abnormal responses to mid-ultraviolet light of cultured fibroblasts from patients with disorders featuring sunlight sensitivity

    International Nuclear Information System (INIS)

    Smith, P.J.; Paterson, M.C.

    1982-01-01

    The postultraviolet light (UV) colony-forming ability and DNA repair properties were examined of human skin fibroblasts derived from two groups of donors at high risk of cancer; (a) persons exhibiting sensitivity to sunlight; and (b) persons with conditions possibly associated with an underlying defect in the repair of radiogenic DNA damage. A comparison was made between the effects of far UV (254 nm) and mid UV (313 nm). Biochemical studies performed on strains sensitive to 313-nm UV alone suggest that their unusual photoresponse is not attributable to defective repair of cyclobutyl pyrimidine dimers. Furthermore, our data imply that thymine glycols are unlikely candidates for the critical lethal lesions in 313-nm UV-sensitive strains. Evidence is presented in support of the contention that mid UV may be partially radiomimetic, thus extending our understanding of the deleterious biological effects of this ubiquitous environmental carcinogen

  13. Sunlight to hydrogen conversion: Design optimization and energy management of concentrated photovoltaic (CPV-Hydrogen) system using micro genetic algorithm

    KAUST Repository

    Burhan, Muhammad

    2016-02-14

    Owing to the intermittent solar irradiance from cloud cover in the diurnal period and unavailability at night time, the practical design of a solar system requires energy backup storage for an uninterrupted supply or for off-grid operation. However, for highly efficient CPV (concentrated photovoltaic) system, the literature is lacking for energy management and optimization algorithm and tool for standalone operation. In this paper, a system with CPV and electrolyser is presented where beam irradiance of sunlight is harnessed to convert the instantaneously generated electricity into useful Hydrogen/Oxygen gas, where they can be stored and re-used for downstream applications such as the fuel cells, etc. The multi-variable design and multi-objective optimization strategies are proposed and presented for a standalone operation of the CPV-Hydrogen system as well as their system performances, particularly electrical rating of CPV based upon the real weather data of Singapore. © 2016 Elsevier Ltd.

  14. Arctic tundra shrub invasion and soot deposition: Consequences for spring snowmelt and near-surface air temperatures

    Science.gov (United States)

    Strack, John E.; Pielke, Roger A.; Liston, Glen E.

    2007-12-01

    Invasive shrubs and soot pollution both have the potential to alter the surface energy balance and timing of snow melt in the Arctic. Shrubs reduce the amount of snow lost to sublimation on the tundra during the winter leading to a deeper end-of-winter snowpack. The shrubs also enhance the absorption of energy by the snowpack during the melt season by converting incoming solar radiation to longwave radiation and sensible heat. Soot deposition lowers the albedo of the snow, allowing it to more effectively absorb incoming solar radiation and thus melt faster. This study uses the Colorado State University Regional Atmospheric Modeling System version 4.4 (CSU-RAMS 4.4), equipped with an enhanced snow model, to investigate the effects of shrub encroachment and soot deposition on the atmosphere and snowpack in the Kuparuk Basin of Alaska during the May-June melt period. The results of the simulations suggest that a complete invasion of the tundra by shrubs leads to a 2.2°C warming of 3 m air temperatures and a 108 m increase in boundary layer depth during the melt period. The snow-free date also occurred 11 d earlier despite having a larger initial snowpack. The results also show that a decrease in the snow albedo of 0.1, owing to soot pollution, caused the snow-free date to occur 5 d earlier. The soot pollution caused a 1.0°C warming of 3 m air temperatures and a 25 m average deepening of the boundary layer.

  15. Effects of gamma rays, ultraviolet radiation, sunlight, microwaves and electromagnetic fields on gene expression mediated by human immunodeficiency virus promoter

    International Nuclear Information System (INIS)

    Libertin, C.R.; Woloschak, G.E.; Panozzo, J.; Groh, K.R.; Chang-Liu, Chin-Mei; Schreck, S.

    1994-01-01

    Previous work by our group and others has shown the modulation of human immunodeficiency virus (HIV) promoter or long terminal repeat (LTR) after exposure to neutrons and ultraviolet radiations. Using HeLa cells stably transfected with a construct containing the chloramphenicol acetyl transferase (CAT) gene, the transcription of which is mediated by the HIV-LTR, we designed experiments to examine the effects of exposure to different types of radiation (such as γ rays, ultraviolet and sunlight irradiations, electromagnetic fields and microwaves) in HIV-LTR-driven expression of CAT. These results demonstrated ultraviolet-light-induced transcription from the HIV promoter, as has been shown by others. Exposure to other DNA-damaging agents such as γ rays and sunlight (with limited exposures) had no significant effect on transcription mediated by HIV-LTR, suggesting that induction of HIV is not mediated by just any type of DNA damage but rather may require specific types of DNA damage. Microwaves did not cause cell killing when cells in culture were exposed in high volumes of medium, and the same cells showed no changes in expression. When microwave exposure was carried out in low volumes of medium (so that excessive heat was generated) induction of HIV-LTR transcription (as assayed by CAT activity) was evident. Electromagnetic field exposures had no effect on expression of HIV-LTR. These results demonstrate that not all types of radiation and not all DNA-damaging agents are capable of inducing HIV. We hypothesize that induction of HIV transcription may be mediated by several different signals exposure to radiation. 22 refs., 8 figs

  16. Roles of Saccharomyces cerevisiae DNA polymerases Polη and Polζ in response to irradiation by simulated sunlight

    Science.gov (United States)

    Kozmin, Stanislav G.; Pavlov, Youri I.; Kunkel, Thomas A.; Sage, Evelyne

    2003-01-01

    Sunlight causes lesions in DNA that if unrepaired and inaccurately replicated by DNA polymerases yield mutations that result in skin cancer in humans. Two enzymes involved in translesion synthesis (TLS) of UV-induced photolesions are DNA polymerase η (Polη) and polymerase ζ (Polζ), encoded by the RAD30A and REV3 genes, respectively. Previous studies have investigated the TLS roles of these polymerases in human and yeast cells irradiated with monochromatic, short wavelength UVC radiation (254 nm). However, less is known about cellular responses to solar radiation, which is of higher and mixed wavelengths (310–1100 nm) and produces a different spectrum of DNA lesions, including Dewar photoproducts and oxidative lesions. Here we report on the comparative cytotoxic and mutagenic effects of simulated sunlight (SSL) and UVC radiation on yeast wild-type, rad30Δ, rev3Δ and rev3Δ rad30Δ strains. The results with SSL support several previous interpretations on the roles of these two polymerases in TLS of photodimers and (6–4) photoproducts derived from studies with UVC. They further suggest that Polη participates in the non-mutagenic bypass of SSL-dependent cytosine-containing Dewar photoproducts and 8-oxoguanine, while Polζ is mainly responsible for the mutagenic bypass of all types of Dewar photoproducts. They also suggest that in the absence of Polζ, Polη contributes to UVC- and SSL-induced mutagenesis, possibly by the bypass of photodimers containing deaminated cytosine. PMID:12888515

  17. Influence of manure age and sunlight on the community structure of cattle fecal bacteria as revealed by Illumina sequencing

    Science.gov (United States)

    Wong, K.; Shaw, T. I.; Oladeinde, A.; Molina, M.

    2013-12-01

    Fecal pollution of environmental waters is a major concern for the general public because exposure to fecal-associated pathogens can have severe impacts on human health. Stream and river impairment due to fecal pollution is largely the result of agricultural activities in the United States. In the last few years, numerous metagenomic studies utilized next generation sequencing to develop microbial community profiles by massively sequencing the 16sRNA hypervariable region. This technology supports the application of water quality assessment such as pathogen detection and fecal source tracking. The bacteria communities of samples in these studies were determined when they were freshly collected; therefore, little is known about how feces age or how environmental stress influences the microbial ecology of fecal materials. In this study we monitored bacteria community changes in cattle feces for 57 days after excretion (day 0, 2, 4 8, 15, 22, 29, 43, 57) by sequencing the 16s variable region 4, using Illumnia MiSeq. Twelve cattle feces were studied; half of the samples were directly exposed to sunlight (unshaded) and half were shaded. Results indicate that the relative abundance (RA) profile in both shaded and unshaded samples rapidly changed from day 0 to 15, but stabilized from day 22 to 57. Firmcutes were the most abundant phylum (~40%) at day 0, but were reduced to rarefaction curve analysis, richness of bacteria diversity in feces decreased as time progressed. Some pathogens such as Campylobacter were detected only at the beginning, meaning they substantially decayed during the course of our study. Overall, this study indicated: (1) sunlight can influence the community structure and (2) after excretion the fecal bacteria diversity can be significantly changed over time. Future studies should therefore use not only the microbial signature of fresh but also moderately aged fecal samples to develop more accurate community profiles for fecal source tracking.

  18. Seasonal Variations in Color Preference.

    Science.gov (United States)

    Schloss, Karen B; Nelson, Rolf; Parker, Laura; Heck, Isobel A; Palmer, Stephen E

    2017-08-01

    We investigated how color preferences vary according to season and whether those changes could be explained by the ecological valence theory (EVT). To do so, we assessed the same participants' preferences for the same colors during fall, winter, spring, and summer in the northeastern United States, where there are large seasonal changes in environmental colors. Seasonal differences were most pronounced between fall and the other three seasons. Participants liked fall-associated dark-warm colors-for example, dark-red, dark-orange (brown), dark-yellow (olive), and dark-chartreuse-more during fall than other seasons. The EVT could explain these changes with a modified version of Palmer and Schloss' (2010) weighted affective valence estimate (WAVE) procedure that added an activation term to the WAVE equation. The results indicate that color preferences change according to season, as color-associated objects become more/less activated in the observer. These seasonal changes in color preferences could not be characterized by overall shifts in weights along cone-contrast axes. Copyright © 2016 Cognitive Science Society, Inc.

  19. Predictability of Western Himalayan river flow: melt seasonal inflow into Bhakra Reservoir in northern India

    Directory of Open Access Journals (Sweden)

    I. Pal

    2013-06-01

    Full Text Available Snowmelt-dominated streamflow of the Western Himalayan rivers is an important water resource during the dry pre-monsoon spring months to meet the irrigation and hydropower needs in northern India. Here we study the seasonal prediction of melt-dominated total inflow into the Bhakra Dam in northern India based on statistical relationships with meteorological variables during the preceding winter. Total inflow into the Bhakra Dam includes the Satluj River flow together with a flow diversion from its tributary, the Beas River. Both are tributaries of the Indus River that originate from the Western Himalayas, which is an under-studied region. Average measured winter snow volume at the upper-elevation stations and corresponding lower-elevation rainfall and temperature of the Satluj River basin were considered as empirical predictors. Akaike information criteria (AIC and Bayesian information criteria (BIC were used to select the best subset of inputs from all the possible combinations of predictors for a multiple linear regression framework. To test for potential issues arising due to multicollinearity of the predictor variables, cross-validated prediction skills of the best subset were also compared with the prediction skills of principal component regression (PCR and partial least squares regression (PLSR techniques, which yielded broadly similar results. As a whole, the forecasts of the melt season at the end of winter and as the melt season commences were shown to have potential skill for guiding the development of stochastic optimization models to manage the trade-off between irrigation and hydropower releases versus flood control during the annual fill cycle of the Bhakra Reservoir, a major energy and irrigation source in the region.

  20. Using the nonlinear aquifer storage-discharge relationship to simulate the base flow of glacier- and snowmelt-dominated basins in northwest China

    Science.gov (United States)

    Gan, R.; Luo, Y.

    2013-09-01

    Base flow is an important component in hydrological modeling. This process is usually modeled by using the linear aquifer storage-discharge relation approach, although the outflow from groundwater aquifers is nonlinear. To identify the accuracy of base flow estimates in rivers dominated by snowmelt and/or glacier melt in arid and cold northwestern China, a nonlinear storage-discharge relationship for use in SWAT (Soil Water Assessment Tool) modeling was developed and applied to the Manas River basin in the Tian Shan Mountains. Linear reservoir models and a digital filter program were used for comparisons. Meanwhile, numerical analysis of recession curves from 78 river gauge stations revealed variation in the parameters of the nonlinear relationship. It was found that the nonlinear reservoir model can improve the streamflow simulation, especially for low-flow period. The higher Nash-Sutcliffe efficiency, logarithmic efficiency, and volumetric efficiency, and lower percent bias were obtained when compared to the one-linear reservoir approach. The parameter b of the aquifer storage-discharge function varied mostly between 0.0 and 0.1, which is much smaller than the suggested value of 0.5. The coefficient a of the function is related to catchment properties, primarily the basin and glacier areas.

  1. Using the nonlinear aquifer storage–discharge relationship to simulate the base flow of glacier- and snowmelt-dominated basins in northwest China

    Directory of Open Access Journals (Sweden)

    R. Gan

    2013-09-01

    Full Text Available Base flow is an important component in hydrological modeling. This process is usually modeled by using the linear aquifer storage–discharge relation approach, although the outflow from groundwater aquifers is nonlinear. To identify the accuracy of base flow estimates in rivers dominated by snowmelt and/or glacier melt in arid and cold northwestern China, a nonlinear storage–discharge relationship for use in SWAT (Soil Water Assessment Tool modeling was developed and applied to the Manas River basin in the Tian Shan Mountains. Linear reservoir models and a digital filter program were used for comparisons. Meanwhile, numerical analysis of recession curves from 78 river gauge stations revealed variation in the parameters of the nonlinear relationship. It was found that the nonlinear reservoir model can improve the streamflow simulation, especially for low-flow period. The higher Nash–Sutcliffe efficiency, logarithmic efficiency, and volumetric efficiency, and lower percent bias were obtained when compared to the one-linear reservoir approach. The parameter b of the aquifer storage–discharge function varied mostly between 0.0 and 0.1, which is much smaller than the suggested value of 0.5. The coefficient a of the function is related to catchment properties, primarily the basin and glacier areas.

  2. Surface Water Geochemistry, Sediment, and Field Parameters During Snowmelt and Monsoons in the New Mexico Reach of the Animas and San Juan Rivers, 2016

    Science.gov (United States)

    Blake, J.; Brown, J. E.; Mast, A.

    2017-12-01

    Following the release of three million gallons of metals laden surface water from the Gold King Mine in August 2015, surface-water samples were collected in the New Mexico reach of the Animas and San Juan Rivers during 2016 snowmelt and in the Animas River during three 2016 monsoonal storms. These samples were evaluated for dissolved (turbidity and specific conductance can provide insight to changes in concentrations of the river on a finer time scale. Regression models developed for selected sites on the Animas and San Juan Rivers show that flow, turbidity and specific conductance may be useful in understanding the relationship between total metal concentrations and real-time parameters. Surrogates for suspended sediment such as hydroacoustic may also be useful, and potentially the best option in this system, for monitoring the concentration of metals in surface water. Further evaluation of the chemistry of the watershed soils and bedrock, the streambed sediments, and suspended sediments will improve understanding of the geochemical processes in the Animas and San Juan Rivers.

  3. A fully automated meltwater monitoring and collection system for spatially distributed isotope analysis in snowmelt-dominated catchments

    Science.gov (United States)

    Rücker, Andrea; Boss, Stefan; Von Freyberg, Jana; Zappa, Massimiliano; Kirchner, James

    2016-04-01

    In many mountainous catchments the seasonal snowpack stores a significant volume of water, which is released as streamflow during the melting period. The predicted change in future climate will bring new challenges in water resource management in snow-dominated headwater catchments and their receiving lowlands. To improve predictions of hydrologic extreme events, particularly summer droughts, it is important characterize the relationship between winter snowpack and summer (low) flows in such areas (e.g., Godsey et al., 2014). In this context, stable water isotopes (18O, 2H) are a powerful tool for fingerprinting the sources of streamflow and tracing water flow pathways. For this reason, we have established an isotope sampling network in the Alptal catchment (46.4 km2) in Central-Switzerland as part of the SREP-Drought project (Snow Resources and the Early Prediction of hydrological DROUGHT in mountainous streams). Samples of precipitation (daily), snow cores (weekly) and runoff (daily) are analyzed for their isotopic signature in a regular cycle. Precipitation is also sampled along a horizontal transect at the valley bottom, and along an elevational transect. Additionally, the analysis of snow meltwater is of importance. As the sample collection of snow meltwater in mountainous terrain is often impractical, we have developed a fully automatic snow lysimeter system, which measures meltwater volume and collects samples for isotope analysis at daily intervals. The system consists of three lysimeters built from Decagon-ECRN-100 High Resolution Rain Gauges as standard component that allows monitoring of meltwater flow. Each lysimeter leads the meltwater into a 10-liter container that is automatically sampled and then emptied daily. These water samples are replaced regularly and analyzed afterwards on their isotopic composition in the lab. Snow melt events as well as system status can be monitored in real time. In our presentation we describe the automatic snow lysimeter

  4. Seasonal and diurnal dependence of Pc 3-5 magnetic pulsation power at geomagnetically conjugate stations in the auroral zones

    International Nuclear Information System (INIS)

    Saito, Hiroaki; Sato, Natsuo; Tonegawa, Yutaka; Yoshino, Takeo; Saemundsson, T.

    1989-01-01

    Seasonal and diurnal variations of Pc 3-5 magnetic pulsation powers have been examined using 2 years of magnetic data from geomagnetically conjugate stations, Syowa in Antarctica and Husafell and Tjoernes in Iceland. The magnetic pulsation powers are found to be relatively higher at the winter hemisphere station than at the summer station. The pulsations observed during equinox show a diurnal dependence, i.e., that the power density is higher in the geomagnetic morning at the stations in Iceland than at Syowa, and this relationship is reversed in the afternoon. The power density ratio of Pc 3 pulsations between the conjugate stations, which is associated with the seasons and with local time, is higher than that of Pc 5. These characteristics can be attributed to the effects of sunlight in the ionosphere, i.e., Pc 3-5 pulsations are shielded when the waves propagate from the magnetosphere to the ground through the sunlit ionosphere

  5. Seasonal Allergies: Diagnosis, Treatment & Research

    Science.gov (United States)

    ... this page please turn JavaScript on. Feature: Seasonal Allergies Diagnosis, Treatment & Research Past Issues / Spring 2015 Table of Contents Diagnosis Testing for Allergies Knowing exactly what you are allergic to can ...

  6. 2012 Swimming Season Fact Sheets

    Science.gov (United States)

    To help beachgoers make informed decisions about swimming at U.S. beaches, EPA annually publishes state-by-state data about beach closings and advisories for the previous year's swimming season. These fact sheets summarize that information by state.

  7. Preparation of K-doped TiO{sub 2} nanostructures by wet corrosion and their sunlight-driven photocatalytic performance

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Eunhye; Jin, Saera; Kim, Jiyoon; Chang, Sung-Jin [Department of Chemistry, Chung-Ang University, Seoul 06974 (Korea, Republic of); Jun, Byung-Hyuk [Neutron Science Division, Korea Atomic Energy Research Institute, Daejeon 34057 (Korea, Republic of); Park, Kwang-Won, E-mail: bryan.kwangwon.park@gmail.com [Department of Chemistry, Chung-Ang University, Seoul 06974 (Korea, Republic of); Hong, Jongin, E-mail: hongj@cau.ac.kr [Department of Chemistry, Chung-Ang University, Seoul 06974 (Korea, Republic of)

    2016-08-30

    Highlights: • Potassium-doped TiO{sub 2} nanowire networks were prepared by the corrosion reaction of Ti nanoparticles in an alkaline solution. • They were applied to sunlight-driven photocatalytic degradation of differently charged dye molecules. • The adsorption of the dye molecules on the photocatalyst surface is crucial for their sunlight-driven photodegradation. - Abstract: K-doped TiO{sub 2} nanowire networks were prepared by the corrosion reaction of Ti nanoparticles in an alkaline (potassium hydroxide: KOH) solution. The prepared nanostructures were characterized by scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) analysis, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, X-ray diffraction (XRD) and photoluminescence (PL) spectra. Their sunlight-driven photocatalytic activity was also investigated with differently charged dye molecules, such as methylene blue, rhodamine B and methyl orange. The adsorption of the dye molecules on the photocatalyst surface would play a critical role in their selective photodegradation under sunlight illumination.

  8. Meteorological Reference Years of Daily Mean Temperature during the Sunlight Time; Anos Tipos de Temperaturas Medias Diarias durante las Horas de Sol

    Energy Technology Data Exchange (ETDEWEB)

    Marchante Jimenez, M.; Ramirez Santigosa, L.N.; Mora Lopez, L.; Sidrach de Cardona Ortin, M.

    2002-07-01

    In this work the characterization of the daily mean temperature during the sunlight time has been analyzed. An algorithm for the hourly series generation from extreme daily values has been applied to evaluate the daily mean temperature during the sunlight time. A generic algorithm has been enounced as a function of the sunrise time. This algorithm allows taking into account the fractions related to the sunrise and sunset hours. This methodology has been applied in data from 45 Spanish stations, uniformly distributed in the Iberian Peninsula. Data for a period of 14 years has been used in most of locations, and once the interest variable has been calculated, the meteorological reference year of the daily mean temperature during the sunlight time has been evaluated in each stations. The next step is the evaluation of the daily mean temperature during the sunlight time in any point into the zone of evaluation, not only in the measured stations. >From the result data in each measured station, an geographic information system has been used in order to calculate the interpolation, obtaining maps with a data each 5 km for each of the 365 days of the year. Then, this results can be superposed with the solar radiation evaluation obtaining the input data for the sizing of the photovoltaic grid connected system in any point of the Spanish geography. (Author) 8 refs.

  9. Efficacy of a dose range of simulated sunlight exposures in raising vitamin D status in South Asian adults: implications for targeted guidance on sun exposure.

    Science.gov (United States)

    Farrar, Mark D; Webb, Ann R; Kift, Richard; Durkin, Marie T; Allan, Donald; Herbert, Annie; Berry, Jacqueline L; Rhodes, Lesley E

    2013-06-01

    Vitamin D is essential for bone health, and cutaneous synthesis is an important source. South Asians cannot attain adequate amounts of vitamin D by following general recommendations on summer sunlight exposure at northerly latitudes, and increased exposure may be appropriate for improving their vitamin D status. We examined the efficacy of a dose range of simulated summer sunlight exposures in raising vitamin D status in UK adults of South Asian ethnicity. In a dose-response study, healthy adults of South Asian ethnicity (n = 60; 20-60 y old) received 1 of 6 ultraviolet exposures ranging from 0.65 to 3.9 standard erythema doses (SEDs), which were equivalent to 15-90 min unshaded noontime summer sunlight at 53.5°N (Manchester, United Kingdom), 3 times/wk for 6 wk, while wearing casual clothes that revealed a 35% skin area. Serum 25-hydroxyvitamin D [25(OH)D] was measured weekly, and dietary vitamin D was estimated. At baseline, all completing participants (n = 51) were vitamin D insufficient [25(OH)D concentrations 10 ng/mL. Targeted guidance on sunlight exposure could usefully enhance vitamin D status to avoid deficiency [25(OH)D concentration >10 ng/mL] in South Asians living at latitudes distant from the equator. This trial was registered at the ISRCTN Register (www.isrctn.org) as 07565297.

  10. Documentation of a heat and water transfer model for seasonally frozen soils with application to a precipitation-runoff model

    Science.gov (United States)

    Emerson, Douglas G.

    1991-01-01

    A model that simulates heat and water transfer in soils during freezing and thawing periods was developed and incorporated into the U.S. Geological Survey's Precipitation-Runoff Modeling System. The transfer of heat 1s based on an equation developed from Fourier's equation for heat flux. Field capacity and infiltration rate can vary throughout the freezing and thawing period, depending on soil conditions and rate and timing of snowmelt. The transfer of water within the soil profile is based on the concept of capillary forces. The model can be used to determine the effects of seasonally frozen soils on ground-water recharge and surface-water runoff. Data collected for two winters, 1985-86 and 1986-87, on three runoff plots were used to calibrate and verify the model. The winter of 1985-86 was colder than normal and snow cover was continuous throughout the winter. The winter of 1986-87 was wanner than normal and snow accumulated for only short periods of several days.Runoff, snowmelt, and frost depths were used as the criteria for determining the degree of agreement between simulated and measured data. The model was calibrated using the 1985-86 data for plot 2. The calibration simulation agreed closely with the measured data. The verification simulations for plots 1 and 3 using the 1985-86 data and for plots 1 and 2 using the 1986-87 data agreed closely with the measured data. The verification simulation for plot 3 using the 1986-87 data did not agree closely. The recalibratlon simulations for plots 1 and 3 using the 1985-86 data Indicated small improvement because the verification simulations for plots 1 and 3 already agreed closely with the measured data.

  11. Extended season for northern butterflies.