WorldWideScience

Sample records for hg wet deposition

  1. Modeled Wet Nitrate Deposition

    Data.gov (United States)

    U.S. Environmental Protection Agency — Modeled data on nitrate wet deposition was obtained from Dr. Jeff Grimm at Penn State Univ. Nitrate wet depostion causes acidification and eutrophication of surface...

  2. European wet deposition maps based on measurements

    NARCIS (Netherlands)

    Leeuwen EP van; Erisman JW; Draaijers GPJ; Potma CJM; Pul WAJ van; LLO

    1995-01-01

    To date, wet deposition maps on a European scale have been based on long-range transport model results. For most components wet deposition maps based on measurements are only available on national scales. Wet deposition maps of acidifying components and base cations based on measurements are needed

  3. European wet deposition maps based on measurements

    NARCIS (Netherlands)

    Leeuwen EP van; Erisman JW; Draaijers GPJ; Potma CJM; Pul WAJ van; LLO

    1995-01-01

    To date, wet deposition maps on a European scale have been based on long-range transport model results. For most components wet deposition maps based on measurements are only available on national scales. Wet deposition maps of acidifying components and base cations based on measurements are needed

  4. Mercury speciation in wet deposition samples collected from a coastal area of Minamata Bay

    Science.gov (United States)

    Marumoto, Kohji; Matsuyama, Akito

    2014-04-01

    To better understand the methylation and demethylation of mercury (Hg) in the atmosphere, monomethyl mercury (MMHg) concentrations in wet deposition samples collected in the Minamata Bay area from September, 2009 to August, 2010 were determined. The concentrations of total Hg (dissolved Hg + particulate Hg) and dissolved reactive Hg were also measured. The volume-weighted mean concentrations of dissolved MMHg and total Hg were 0.061 and 5.9 ng L-1, respectively. Almost 90% of total Hg was in the dissolved phase and dissolved reactive Hg was the dominant Hg species in the wet deposition. The wet deposition fluxes of total Hg and reactive Hg increased in the rainy season (summer and fall), while the concentrations and wet deposition fluxes of MMHg were higher in winter and spring than in summer. Factors affecting this seasonal variation of MMHg were also considered. The MMHg in wet depositions may be decomposed by the increased levels of UV radiation in summer months, although MMHg can also be emitted from anthropogenic and biogenic sources and/or produced by photochemical reactions. Long-range transport from the Asian continent may also contribute to the seasonal variation of the wet MMHg deposition flux.

  5. Assessing the emission sources of atmospheric mercury in wet deposition across Illinois.

    Science.gov (United States)

    Gratz, Lynne E; Keeler, Gerald J; Morishita, Masako; Barres, James A; Dvonch, J Timothy

    2013-03-15

    From August 4, 2007 to August 31, 2009, we collected event-based precipitation samples for mercury (Hg) and trace element analyses at four sites in Illinois (IL), USA. The objectives of these measurements were to quantify Hg wet deposition across the state, and to assess the contributions to Hg in precipitation from major local and regional emission sources. Monitoring sites were located, from north to south, in Chicago, Peoria, Nilwood, and Carbondale, IL. Measurements from these four sites demonstrated that a clear spatial gradient in Hg wet deposition was not evident across the state. Each site received>10μgm(-2) of Hg wet deposition annually, and these observed values were comparable to annual Hg wet deposition measurements from other event-based precipitation monitoring sites in source-impacted areas of the Midwestern U.S. We applied the multivariate statistical receptor model, Positive Matrix Factorization (EPA PMF v3.0), to the measured Hg and trace element wet deposition amounts at the four sites. Results suggested that 50% to 74% of total Hg wet deposition at each site could be attributed to coal combustion emissions. The other source signatures identified in the precipitation compositions included cement manufacturing, mixed metal smelting/waste incineration, iron-steel production, and a phosphorus source. We also applied a hybrid receptor model, Quantitative Transport Bias Analysis (QTBA), to the Hg wet deposition datasets to identify the major source regions associated with the measured values. The calculated QTBA probability fields suggested that transport from urban/industrial areas, such as Chicago/Gary, St. Louis, and the Ohio River Valley, resulted in some of the highest estimated event-based Hg wet deposition amounts at the four sites (potential mass transfer of up to 0.32μgm(-2)). The combined application of PMF and QTBA supported the hypothesis that local and regional coal combustion was the largest source of Hg wet deposition in Illinois.

  6. Assessing the Emission Sources of Atmospheric Mercury in Wet Deposition Across Illinois, USA

    Directory of Open Access Journals (Sweden)

    Gratz L. E.

    2013-04-01

    Full Text Available From August 2007 to August 2009, we collected event-based precipitation samples for mercury (Hg and trace element analysis at four sites in Illinois, USA. The objectives of these measurements were to quantify the levels of Hg wet deposition across the state, and to assess the contributions to Hg in precipitation from major local and regional emission sources. The measurement sites were located in Chicago, Peoria, Nilwood, and Carbondale, IL. We were not able to identify a clear spatial gradient in Hg wet deposition among the sites. At all four locations we frequently observed Hg concentrations in precipitation > 25 ng/L, while each site received > 10 μg/m2 of Hg wet deposition annually, suggesting a substantial impact from local and regional anthropogenic emission sources. We applied the multivariate statistical receptor model Positive Matrix Factorization (PMF to the measured Hg and trace element wet deposition amounts at the four sites. The results suggested that 60-83% of total Hg deposition at each site could be attributed to coal combustion emissions. Although we identified other source signatures in the precipitation composition, including cement manufacturing, metal smelting / waste incineration, and iron-steel production, these sources contributed substantially less to the measured amounts of Hg wet deposition. We also applied the hybrid receptor model Quantitative Transport Bias Analysis (QTBA to the Hg wet deposition data from each site to identify the major source regions associated with the measured values. Results suggested that sources in the Chicago/Gary, St. Louis, and Ohio River Valley urban/industrial areas had a substantial impact on Hg wet deposition, strongly supporting the conclusion that local and regional coal combustion was the largest source of Hg wet deposition in Illinois.

  7. High mercury wet deposition at a “clean Air” site in Puerto Rico

    Science.gov (United States)

    Shanley, James B.; Engle, Mark A.; Scholl, Martha A.; Krabbenhoft, David P.; Brunette, Robert; Olson, Mark L.; Conroy, Mary E.

    2015-01-01

    Atmospheric mercury deposition measurements are rare in tropical latitudes. Here we report on seven years (April 2005 to April 2012, with gaps) of wet Hg deposition measurements at a tropical wet forest in the Luquillo Mountains, northeastern Puerto Rico, U.S. Despite receiving unpolluted air off the Atlantic Ocean from northeasterly trade winds, during two complete years the site averaged 27.9 μg m–2 yr–1 wet Hg deposition, or about 30% more than Florida and the Gulf Coast, the highest deposition areas within the U.S. These high Hg deposition rates are driven in part by high rainfall, which averaged 2855 mm yr–1. The volume-weighted mean Hg concentration was 9.8 ng L–1, and was highest during summer and lowest during the winter dry season. Rainout of Hg (decreasing concentration with increasing rainfall depth) was minimal. The high Hg deposition was not supported by gaseous oxidized mercury (GOM) at ground level, which remained near global background concentrations (<10 pg m–3). Rather, a strong positive correlation between Hg concentrations and the maximum height of rain detected within clouds (echo tops) suggests that droplets in high convective cloud tops scavenge GOM from above the mixing layer. The high wet Hg deposition at this “clean air” site suggests that other tropical areas may be hotspots for Hg deposition as well.

  8. Atmospheric mercury simulation using the CMAQ model: formulation description and analysis of wet deposition results

    Science.gov (United States)

    Bullock, O. Russell; Brehme, Katherine A.

    The community multiscale air quality (CMAQ) modeling system has been adapted to simulate the emission, transport, transformation and deposition of atmospheric mercury (Hg) in three distinct forms: elemental Hg gas, reactive gaseous Hg, and particulate Hg. Emissions of Hg are currently defined from information published in the Environmental Protection Agency's Mercury Study Report to Congress. The atmospheric transport of these three forms of Hg is simulated in the same manner as for all other substances simulated by the CMAQ model to date. Transformations of Hg are simulated with four new chemical reactions within the standard CMAQ gaseous chemistry framework and a highly modified cloud chemistry mechanism which includes a compound-specific speciation for oxidized forms of Hg, seven new aqueous-phase Hg reactions, six aqueous Hg chemical equilibria, and a two-way mechanism for the sorption of dissolved oxidized Hg to elemental carbon particles. The CMAQ Hg model simulates the partitioning of reactive gaseous Hg between air and cloud water based on the Henry's constant for mercuric chloride. Henry's equilibrium is assumed for elemental Hg also. Particulate Hg is assumed to be incorporated into the aqueous medium during cloud nucleation. Wet and dry deposition is simulated for each of the three forms of Hg. Wet deposition rate is calculated based on precipitation information from the CMAQ meteorological processor and the physicochemical Hg speciation in the cloud chemistry mechanism. Dry deposition rate is calculated based on dry deposition velocity and air concentration information for each of the three forms of Hg. The horizontal modeling domain covers the central and eastern United States and adjacent southern Canada. An analysis of simulated Hg wet deposition versus weekly observations is performed. The results are described for two evaluation periods: 4 April-2 May 1995, and 20 June-18 July 1995.

  9. Atmospheric wet and litterfall mercury deposition at urban and rural sites in China

    Science.gov (United States)

    Fu, Xuewu; Yang, Xu; Lang, Xiaofang; Zhou, Jun; Zhang, Hui; Yu, Ben; Yan, Haiyu; Lin, Che-Jen; Feng, Xinbin

    2016-09-01

    Mercury (Hg) concentrations and deposition fluxes in precipitation and litterfall were measured at multiple sites (six rural sites and an urban site) across a broad geographic area in China. The annual deposition fluxes of Hg in precipitation at rural sites and an urban site were 2.0 to 7.2 and 12.6 ± 6.5 µg m-2 yr-1, respectively. Wet deposition fluxes of Hg at rural sites showed a clear regional difference with elevated deposition fluxes in the subtropical zone, followed by the temporal zone and arid/semi-arid zone. Precipitation depth is the primary influencing factor causing the variation of wet deposition. Hg fluxes through litterfall ranged from 22.8 to 62.8 µg m-2 yr-1, higher than the wet deposition fluxes by a factor of 3.9 to 8.7 and representing approximately 75 % of the total Hg deposition at the forest sites in China. This suggests that uptake of atmospheric Hg by foliage is the dominant pathway to remove atmospheric Hg in forest ecosystems in China. Wet deposition fluxes of Hg at rural sites of China were generally lower compared to those in North America and Europe, possibly due to a combination of lower precipitation depth, lower GOM concentrations in the troposphere and the generally lower cloud base heights at most sites that wash out a smaller amount of GOM and PBM during precipitation events.

  10. Five-year records of mercury wet deposition flux at GMOS sites in the Northern and Southern hemispheres

    Science.gov (United States)

    Sprovieri, Francesca; Pirrone, Nicola; Bencardino, Mariantonia; D'Amore, Francesco; Angot, Helene; Barbante, Carlo; Brunke, Ernst-Günther; Arcega-Cabrera, Flor; Cairns, Warren; Comero, Sara; Diéguez, María del Carmen; Dommergue, Aurélien; Ebinghaus, Ralf; Feng, Xin Bin; Fu, Xuewu; Garcia, Patricia Elizabeth; Gawlik, Bernd Manfred; Hageström, Ulla; Hansson, Katarina; Horvat, Milena; Kotnik, Jože; Labuschagne, Casper; Magand, Olivier; Martin, Lynwill; Mashyanov, Nikolay; Mkololo, Thumeka; Munthe, John; Obolkin, Vladimir; Ramirez Islas, Martha; Sena, Fabrizio; Somerset, Vernon; Spandow, Pia; Vardè, Massimiliano; Walters, Chavon; Wängberg, Ingvar; Weigelt, Andreas; Yang, Xu; Zhang, Hui

    2017-02-01

    The atmospheric deposition of mercury (Hg) occurs via several mechanisms, including dry and wet scavenging by precipitation events. In an effort to understand the atmospheric cycling and seasonal depositional characteristics of Hg, wet deposition samples were collected for approximately 5 years at 17 selected GMOS monitoring sites located in the Northern and Southern hemispheres in the framework of the Global Mercury Observation System (GMOS) project. Total mercury (THg) exhibited annual and seasonal patterns in Hg wet deposition samples. Interannual differences in total wet deposition are mostly linked with precipitation volume, with the greatest deposition flux occurring in the wettest years. This data set provides a new insight into baseline concentrations of THg concentrations in precipitation worldwide, particularly in regions such as the Southern Hemisphere and tropical areas where wet deposition as well as atmospheric Hg species were not investigated before, opening the way for future and additional simultaneous measurements across the GMOS network as well as new findings in future modeling studies.

  11. ROE Wet Sulfate Deposition 2009-2011

    Data.gov (United States)

    U.S. Environmental Protection Agency — The raster data represent the amount of wet sulfate deposition in kilograms per hectare from 2009 to 2011. Summary data in this indicator were provided by EPA’s...

  12. ROE Wet Nitrate Deposition 1989-1991

    Data.gov (United States)

    U.S. Environmental Protection Agency — The raster data represent the amount of wet nitrate deposition in kilograms per hectare from 1989 to 1991. Summary data in this indicator were provided by EPA’s...

  13. ROE Wet Nitrate Deposition 2011-2013

    Data.gov (United States)

    U.S. Environmental Protection Agency — The raster data represent the amount of wet nitrate deposition in kilograms per hectare from 2011 to 2013. Summary data in this indicator were provided by EPA’s...

  14. Controlling Factors of Long-Term Trends in Mercury Wet Deposition and Precipitation Concentrations at Huntington Wildlife Forest

    Science.gov (United States)

    Ye, Z.; Mao, H.; Driscoll, C. T.

    2015-12-01

    Observations from the Mercury Deposition Network (MDN) at Huntington Wildlife Forest (HWF) suggested that a significant decline (r2 = 0.34, p = 0.03) from 2000 to 2013 in volume weighted mean (VWM) Hg concentrations in precipitation was linked to Hg emission decreases in the United States, especially in the Northeast and Midwest, and yet Hg wet deposition has remained fairly constant over the past two decades. The present study aimed to investigate the climatic, terrestrial, and anthropogenic factors that influenced the decadal pattern in Hg wet deposition in upstate NY. In spring and summer, when Hg wet deposition was the strongest, significant positive correlation (r2 = 0.89, p < 0.0001 in spring; r2 = 0.58, p = 0.002 in summer) of Hg wet deposition with precipitation was found. Increases in precipitation during these seasons could offset the decreasing of Hg concentration in precipitation. Besides, springtime positive correlation (r2 = 0.35, p = 0.02) between precipitation and the North Atlantic Oscillation (NAO) index together with geopotential height and wind speed analysis indicated that large-scale dynamical forcing was likely an important factor influencing the long term trend in springtime Hg wet deposition at HWF. To further quantify the roles of meteorological and anthropogenic factors in Hg wet deposition, the Community Multiscale Air Quality (CMAQ) model was employed using an algorithm depicting state-of-the-art Hg chemistry mechanism and up-to-date Hg emission inventories evaluated with MDN and Atmospheric Mercury Network (AMNet) measurement data. CMAQ simulations with a constant vs. realistic meteorological conditions for multiple warm seasons (including spring and summer) were used to characterize and quantify the impacts of inter-annual variability of precipitation and atmospheric circulation on Hg wet deposition. In addition, contributions to Hg wet deposition from decreases in anthropogenic emissions in NYS and nation-wide were quantified from

  15. Bioindication of volcanic mercury (Hg) deposition around Mt Etna (Sicily)

    Science.gov (United States)

    Martin, R.; Witt, M. L.; Sawyer, G. M.; Watt, S.; Bagnato, E.; Calabrese, S.; Aiuppa, A.; Delmelle, P.; Pyle, D. M.; Mather, T. A.

    2012-12-01

    Mt. Etna is a major natural source of Hg to the Mediterranean region. Total mercury concentrations, [Hg]tot, in Castanea sativa (sweet chestnut) leaves sampled 7-13 km from Etna's vents (during six campaigns in 2005-2011) were determined using atomic absorption spectroscopy. [Hg]tot in C. sativa was greatest on Etna's SE flank reflecting Hg deposition from the typically overhead volcanic plume. When adjusted for leaf age, [Hg]tot in C. sativa also increased with recent eruptive activity. [Hg]tot in C. sativa was not controlled by [Hg]tot in soils, which instead was greatest on the (upwind) NW flank and correlated strongly with soil organic matter (% Org). Our results suggest that at least ~1% of Hg emitted from Etna is deposited proximally, supporting recent measurement and model results which indicate that GEM (Hg0; the dominant form of Hg in high temperature magmatic gases) is oxidised rapidly to RGM and Hgp in ambient temperature volcanic plumes. Samples of C. sativa and soils were also collected in July and September 2012 alongside SO2 and acid gas diffusion tube samples. These new samples will enable us to investigate Hg accumulation over a single growth season with reference to the exposure of vegetation to volcanic gases and particles.

  16. Four-year record of mercury wet deposition in one typical industrial city in southwest China

    Science.gov (United States)

    Qin, Caiqing; Wang, Yongmin; Peng, Yulong; Wang, Dingyong

    2016-10-01

    During the period from December 2010 to November 2014, long-term monitoring of Hg wet deposition was conducted at three sites in Chongqing. The four-year volume-weighted mean concentrations (VWC) of total mercury (THg) and methylmercury (MeHg) in precipitation were 34.25 ng L-1 and 0.48 ng L-1, respectively. The average annual wet deposition fluxes were 37.83 ± 11.53 μg m-2 yr-1 for THg and 0.61 ± 0.19 μg m-2 yr-1 for MeHg. Besides, the average proportion of MeHg in THg was 1.41%. These data were well ahead of values observed in most of other areas. The annual VWC of Hg rose remarkably in 2012 and then reached a plateau or climbed mildly in the following 2 years, while its annual wet deposition fluxes saw an upward trend throughout the whole period. In addition, the high figures of Hg concentration were generally found in the non-monsoon seasons, but its elevated wet deposition fluxes normally appeared in the rainy seasons. These characteristics of inter-annual and seasonal changes for VWC and fluxes were observed at every sampling site in this study as well. Besides, there were significantly spatial distributions for VWC and fluxes of THg in the descending order of the downtown (NA), the suburban (BB) and the controlled site (JY). While for MeHg, BB had the largest values, followed by NA and JY. So apart from THg load, the formation of MeHg was influenced by other factors in Chongqing, like the concentration of reactive mercury (RHg) in precipitation. Additionally, particulate bound mercury (PHg) is the dominant form among various Hg species, and atmospheric Hg is effectively eliminated during the initial period of the rain event and the below-cloud scavenging is the predominant mechanism contributing Hg to precipitation.

  17. Wet deposition in the northeastern United States

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, J; Mohnen, V; Kadlecek, J

    1980-12-01

    Attempts are made to examine concentration and wet deposition of pollutant material at selected stations within the northeastern United States and to characterize as many events as possible with respect to air mass origin. Further attempts are made to develop a regional pattern for the deposition of dominant ion species. MAP3S (US Multistate Atmospheric Power Production Pollution Study) data for 1977 to 1979 are used to determine concentration and deposition on an event basis from which monthly, seasonal, annual, and cumulative averages are developed. The ARL-ATAD trajectory model is used to characterize individual events as to air mass origin. Case studies are examined to illustrate variability in the chemical composition of precipitation originating from distinctly different air mass trajectories. A difference in concentration of pollution-related ions in precipitation is noted between Midwest/Ohio Valley and Great Lakes/Canadian air mass origins for carefully selected cases. Total deposition of the major ions is examined in an effort to develop a regional pattern for deposition over a period of at least one year. For that purpose, total deposition is normalized to remove the variability in precipitation amounts for inter-station comparison. No marked gradient is noted in the normalized deposition totals within the northeast of the United States. The Adirondack region exhibited the lowest normalized ion deposition value, while the Illinois station showed the highest of the MAP3S network. The data analysis suggest that the acid rain phenomena covers the entire northeast. The concept of large scale mixing emerges to account for the lack of a significant gradient in the normalized deposition.

  18. Wet deposition in the northeastern United States

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, J; Mohnen, V; Kadlecek, J

    1980-12-01

    Attempts are made to examine concentration and wet deposition of pollutant material at selected stations within the northeastern United States and to characterize as many events as possible with respect to air mass origin. Further attempts are made to develop a regional pattern for the deposition of dominant ion species. MAP3S (US Multistate Atmospheric Power Production Pollution Study) data for 1977 to 1979 are used to determine concentration and deposition on an event basis from which monthly, seasonal, annual, and cumulative averages are developed. The ARL-ATAD trajectory model is used to characterize individual events as to air mass origin. Case studies are examined to illustrate variability in the chemical composition of precipitation originating from distinctly different air mass trajectories. A difference in concentration of pollution-related ions in precipitation is noted between Midwest/Ohio Valley and Great Lakes/Canadian air mass origins for carefully selected cases. Total deposition of the major ions is examined in an effort to develop a regional pattern for deposition over a period of at least one year. For that purpose, total deposition is normalized to remove the variability in precipitation amounts for inter-station comparison. No marked gradient is noted in the normalized deposition totals within the northeast of the United States. The Adirondack region exhibited the lowest normalized ion deposition value, while the Illinois station showed the highest of the MAP3S network. The data analysis suggest that the acid rain phenomena covers the entire northeast. The concept of large scale mixing emerges to account for the lack of a significant gradient in the normalized deposition.

  19. Atmospheric total gaseous mercury (TGM concentrations and wet and dry deposition of mercury at a high-altitude mountain peak in south China

    Directory of Open Access Journals (Sweden)

    H. Zhang

    2009-11-01

    Full Text Available China is regarded as the largest contributor of mercury (Hg to the global atmospheric Hg budget. However, concentration levels and depositions of atmospheric Hg in China are poorly known. Continuous measurements of atmospheric total gaseous mercury (TGM were carried out from May 2008 to May 2009 at the summit of Mt. Leigong in south China. Wet and dry deposition fluxes of Hg were also calculated following collection of precipitation, throughfall and litterfall. Atmospheric TGM concentrations averaged 2.80±1.51 ng m−3, which was highly elevated compared to global background values but much lower than semi-rural and industrial/urban areas in China, indicating great emissions of Hg in central, south and southwest China. Seasonal and diurnal variations of TGM were observed, which reflected variations in source intensity, deposition processes and meteorological factors. Wet deposition of Hg was quite low, while its dry deposition of Hg (litterfall + throughfall-direct wet deposition constituted a major portion of total deposition (~88% for total mercury (THg and 84% for methyl mercury (MeHg. This highlights the importance of vegetation to Hg atmospheric cycling. In a remote forest ecosystem of China, dry deposition of TGM, especially gaseous elemental mercury (GEM, was very important for the depletion of atmospheric Hg. Elevated TGM level in ambient air may accelerate the foliar uptake of Hg through air which may partly explain the elevated Hg dry deposition fluxes observed in Mt. Leigong.

  20. Trends in mercury wet deposition and mercury air concentrations across the U.S. and Canada

    Science.gov (United States)

    Weiss-Penzias, Peter S.; Gay, David A.; Brigham, Mark E.; Parsons, Matthew T.; Gustin, Mae S.; ter Shure, Arnout

    2016-01-01

    This study examined the spatial and temporal trends of mercury (Hg) in wet deposition and air concentrations in the United States (U.S.) and Canada between 1997 and 2013. Data were obtained from the National Atmospheric Deposition Program (NADP) and Environment Canada monitoring networks, and other sources. Of the 19 sites with data records from 1997–2013, 53% had significant negative trends in Hg concentration in wet deposition, while no sites had significant positive trends, which is in general agreement with earlier studies that considered NADP data up until about 2010. However, for the time period 2007–2013 (71 sites), 17% and 13% of the sites had significant positive and negative trends, respectively, and for the time period 2008–2013 (81 sites) 30% and 6% of the sites had significant positive and negative trends, respectively. Non-significant positive tendencies were also widespread. Regional trend analyses revealed significant positive trends in Hg concentration in the Rocky Mountains, Plains, and Upper Midwest regions for the recent time periods in addition to significant positive trends in Hg deposition for the continent as a whole. Sulfate concentration trends in wet deposition were negative in all regions, suggesting a lower importance of local Hg sources. The trend in gaseous elemental Hg from short-term datasets merged as one continuous record was broadly consistent with trends in Hg concentration in wet deposition, with the early time period (1998–2007) producing a significantly negative trend (− 1.5 ± 0.2% year− 1) and the recent time period (2008–2013) displaying a flat slope (− 0.3 ± 0.1% year− 1, not significant). The observed shift to more positive or less negative trends in Hg wet deposition primarily seen in the Central-Western regions is consistent with the effects of rising Hg emissions from regions outside the U.S. and Canada and the influence of long-range transport in the free troposphere.

  1. Mercury Wet Scavenging and Deposition Differences by Precipitation Type.

    Science.gov (United States)

    Kaulfus, Aaron S; Nair, Udaysankar; Holmes, Christopher D; Landing, William M

    2017-03-07

    We analyze the effect of precipitation type on mercury wet deposition using a new database of individual rain events spanning the contiguous United States. Measurements from the Mercury Deposition Network (MDN) containing single rainfall events were identified and classified into six precipitation types. Mercury concentrations in surface precipitation follow a power law of precipitation depth that is modulated by precipitation system morphology. After controlling for precipitation depth, the highest mercury deposition occurs in supercell thunderstorms, with decreasing deposition in disorganized thunderstorms, quasi-linear convective systems (QLCS), extratropical cyclones, light rain, and land-falling tropical cyclones. Convective morphologies (supercells, disorganized, and QLCS) enhance wet deposition by a factor of at least 1.6 relative to nonconvective morphologies. Mercury wet deposition also varies by geographic region and season. After controlling for other factors, we find that mercury wet deposition is greater over high-elevation sites, seasonally during summer, and in convective precipitation.

  2. ROE Wet Sulfate Deposition Raster 2011-2013

    Data.gov (United States)

    U.S. Environmental Protection Agency — The raster data represent the amount of wet sulfate deposition in kilograms per hectare from 2011 to 2013. Summary data in this indicator were provided by EPA’s...

  3. ROE Wet Sulfate Deposition Raster 1989-1991

    Data.gov (United States)

    U.S. Environmental Protection Agency — The raster data represent the amount of wet sulfate deposition in kilograms per hectare from 1989 to 1991. Summary data in this indicator were provided by EPA’s...

  4. Inorganic Nitrogen Wet Deposition for the Conterminous United States, 1962

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Annual inorganic nitrogen wet deposition were estimated for the conterminous United States for 1962. The estimates were derived from inorganic nitrogen...

  5. Inorganic Nitrogen Wet Deposition for the Conterminous United States, 1984

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Annual inorganic nitrogen wet deposition were estimated for the conterminous United States for 1984. The estimates were derived from inorganic nitrogen...

  6. Inorganic Nitrogen Wet Deposition for the Conterminous United States, 1963

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Annual inorganic nitrogen wet deposition were estimated for the conterminous United States for 1963. The estimates were derived from inorganic nitrogen...

  7. Inorganic Nitrogen Wet Deposition for the Conterminous United States, 1983

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Annual inorganic nitrogen wet deposition were estimated for the conterminous United States for 1983. The estimates were derived from inorganic nitrogen...

  8. Inorganic Nitrogen Wet Deposition for the Conterminous United States, 1961

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Annual inorganic nitrogen wet deposition were estimated for the conterminous United States for 1961. The estimates were derived from inorganic nitrogen...

  9. Inorganic Nitrogen Wet Deposition for the Conterminous United States, 1964

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Annual inorganic nitrogen wet deposition were estimated for the conterminous United States for 1964. The estimates were derived from inorganic nitrogen...

  10. Enhanced Hg{sup 2+} removal and Hg{sup 0} re-emission control from wet fuel gas desulfurization liquors with additives

    Energy Technology Data Exchange (ETDEWEB)

    Tingmei Tang; Jiang Xu; Rongjie Lu; Jingjing Wo; Xinhua Xu [Zhejiang University, Hangzhou (China). Department of Environmental Engineering

    2010-12-15

    Secondary atmospheric pollutions may result from wet flue gas desulfurization (FGD) systems caused by the reduction of Hg{sup 2+} to Hg{sup 0}. The present study employed three agents: Na{sub 2}S, 2,4,6-trimercaptotiazine, trisodium salt nonahydrate (TMT) and sodium dithiocarbamate (DTCR) to precipitate aqueous Hg{sup 2+} in simulated desulfurization solutions. The effects of the precipitator's dosing quantity, the initial pH value, the reaction temperature, the concentrations of Cl{sup -} and other metal ions (e.g. Cu{sup 2+} and Pb{sup 2+}) on Hg{sup 2+} removal were studied. A linear relationship was observed between Hg{sup 2+} removal efficiency and the increasing precipitator's doses along with initial pH. The addition of chloride and metal ions impaired the Hg{sup 2+} removal from solutions due to the complexation of Cl{sup -} and Hg{sup 2+} as well as the chelating competition between Hg{sup 2+} and other metal ions. Based on a comprehensive comparison of the treatment effects, DTCR was found to be the most effective precipitating agent. Moreover, all the precipitating agents were potent enough to inhibit Hg{sup 2+} reduction as well as Hg{sup 0} re-emission from FGD liquors. More than 90% Hg{sup 2+} was captured by precipitating agents while Hg{sup 2+} reduction efficiency decreased from 54% to just less than 3%. The additives could efficiently control the secondary Hg{sup 0} pollution from FGD liquors. 21 refs., 6 figs.

  11. Electrophoretic deposition of titania nanoparticles: Wet density of deposits during EPD

    Indian Academy of Sciences (India)

    Morteza Farrokhi-Rad; Taghi Shahrabi; Shirin Khanmohammadi

    2014-08-01

    Electrophoretic deposition (EPD) of titania nanoparticles was performed at different voltages and times. The wet density of deposits was calculated according to the Archimedes’ principle. The wet density as well as the electric field over the deposits increased with time and attained the plateau at longer times. The velocity at which particles attach to the deposit, strongly influences its wet density at initial times. However, the effect of electro-osmotic flow is dominant at longer times. The coating with higher wet density had the higher corrosion resistance in Ringer’s solution at 37.5 °C due to its closely packed and crack free microstructure.

  12. Comparison of Mercury Mass Loading in Streams to Wet and Dry Atmospheric Deposition in Watersheds of the Western US: Evidence for Non-Atmospheric Mercury Sources

    Science.gov (United States)

    Domagalski, J. L.; Majewski, M. S.; Alpers, C. N.; Eckley, C.

    2015-12-01

    Many streams in the western United States (US) are listed as impaired by mercury (Hg), and it is important to understand the magnitudes of the various sources in order to implement management strategies. Atmospheric deposition of Hg and can be a major source of aquatic contamination, along with mine wastes, and other sources. Prior studies in the eastern US have shown that streams deliver less than 50% of the atmospherically deposited Hg on an annual basis. In this study, we compared annual stream Hg loads for 20 watersheds in the western US to measured wet and modeled dry deposition. Land use varies from undisturbed to mixed (agricultural, urban, forested, mining). Data from the Mercury Deposition Network was used to estimate Hg input from precipitation. Dry deposition was not directly measured, but can be modeled using the Community Multi-scale Air Quality model. At an undeveloped watershed in the Rocky Mountains, the ratio of stream Hg load to atmospheric deposition was 0.2 during a year of average precipitation. In contrast, at the Carson River in Nevada, with known Hg contamination from historical silver mining with Hg amalgamation, stream export exceeded atmospheric deposition by a factor of 60, and at a small Sierran watershed with gold mining, the ratio was 70. Larger watersheds with mixed land uses, tend to have lower ratios of stream export relative to atmospheric deposition suggesting storage of Hg. The Sacramento River was the largest watershed for which Hg riverine loads were available with an average ratio of stream Hg export to atmospheric deposition of 0.10. Although Hg was used in upstream historical mining operations, the downstream river Hg load is partially mitigated by reservoirs, which trap sediment. This study represents the first compilation of riverine Hg loads in comparison to atmospheric deposition on a regional scale; the approach may be useful in assessing the relative importance of atmospheric and non-atmospheric Hg sources.

  13. Lacustrine responses to decreasing wet mercury deposition rates: results from a case study in northern Minnesota

    Science.gov (United States)

    Brigham, Mark E.; Sandheinrich, Mark B.; Gay, David A.; Maki, Ryan P.; Krabbenhoft, David P.; Wiener, James G.

    2014-01-01

    We present a case study comparing metrics of methylmercury (MeHg) contamination for four undeveloped lakes in Voyageurs National Park to wet atmospheric deposition of mercury (Hg), sulfate (SO4–2), and hydrogen ion (H+) in northern Minnesota. Annual wet Hg, SO4–2, and H+ deposition rates at two nearby precipitation monitoring sites indicate considerable decreases from 1998 to 2012 (mean decreases of 32, 48, and 66%, respectively). Consistent with decreases in the atmospheric pollutants, epilimnetic aqueous methylmercury (MeHgaq) and mercury in small yellow perch (Hgfish) decreased in two of four lakes (mean decreases of 46.5% and 34.5%, respectively, between 2001 and 2012). Counter to decreases in the atmospheric pollutants, MeHgaq increased by 85% in a third lake, whereas Hgfish increased by 80%. The fourth lake had two disturbances in its watershed during the study period (forest fire; changes in shoreline inundation due to beaver activity); this lake lacked overall trends in MeHgaq and Hgfish. The diverging responses among the study lakes exemplify the complexity of ecosystem responses to decreased loads of atmospheric pollutants.

  14. Geological behavior of wet outflow deposition fly ash

    Institute of Scientific and Technical Information of China (English)

    周德泉; 赵明华; 刘宏利; 周毅; 严聪

    2008-01-01

    The geological behaviors of wet outflow deposition fly ash were investigated, including the feature of in-situ single and even bridge cone penetration test (CPT) curves, the change of the penetration parameters and vane strength with the increase of depth and the difference of the penetration resistance on and down the water level. Drilling, CPT and vane shear test were carried out in silty clay, fine sand, and fly ash of the ash-dam. The CPT curves of the fly ash do not show a critical depth. The cone resistance (qc) of the fly ash is smaller than that of silty clay or sand; the friction resistance is smaller than that of filling silty clay, similar to that of deposition silty clay or more than that of fine sand; the friction ratio is smaller than that of filling silty clay, or more than that of deposition silty clay or much more than that of fine sand. The specific penetration resistance (ps) is similar to that of filling silty clay, or more than that of deposition silty clay. There is a clear interface effect between the deposition fly ash and the clay. Interface effect of ps-h curve at the groundwater table is clear, and ps of the fly ash reduces significantly under the table. The vane strength of the fly ash increases as the depth increases. The deposition fly ash with wet outflow is similar to silt in the geological behavior.

  15. Formation of PdHg by reaction of palladium thin film contacts deposited onto mercuric iodide ({alpha}-HgI{sub 2}) radiation detector crystals

    Energy Technology Data Exchange (ETDEWEB)

    Medlin, D.L. [Sandia National Labs., Livermore, CA (United States); Van Scyoc, J.M. [Carnegie-Mellon Univ., Pittsburgh, PA (United States). Dept. of Electrical and Computer Engineering; Gilbert, T.S. [Carnegie-Mellon Univ., Pittsburgh, PA (United States). Dept. of Electrical and Computer Engineering; Schlesinger, T.E. [Carnegie-Mellon Univ., Pittsburgh, PA (United States). Dept. of Electrical and Computer Engineering; Boehme, D. [Sandia National Labs., Livermore, CA (United States); Schieber, M. [Sandia National Labs., Livermore, CA (United States); Natarajan, M. [TN Technologies, Inc., Round Rock, TX (United States); James, R.B. [Sandia National Labs., Livermore, CA (United States)

    1996-10-01

    The microstructure and phase distribution of palladium thin films sputter deposited onto {alpha}-HgI{sub 2} for use as electrical contacts in radiation detectors are investigated using electron microscopy. Our results show a limited reaction to form palladium mercuride (PdHg). It is shown that the formation of PdHg via several reaction pathways is thermodynamically feasible. (orig.).

  16. Removal of Hg{sup 0} from flue gases in wet FGD by catalytic oxidation with air - An experimental study

    Energy Technology Data Exchange (ETDEWEB)

    Andrej Stergarsek; Milena Horvat; Peter Frkal; Jost Stergarsek [' Jozef Stefan' Institute, Ljubljana (Slovenia)

    2010-11-15

    Research efforts are being focused on the development of mercury removal technologies, mainly directed to two alternative approaches: (I) the enhancement of homogeneous oxidation in the flue gases of Hg{sup 0} to water soluble Hg{sup 2+} by the addition of chlorides or bromides to the boiler or; (ii) the adsorption of Hg{sup 2+} and Hg{sup 0} on impregnated activated carbon (AC). A third option gaining more attention lately is based on the oxidation and retention of dissolved Hg{sup 0} in the wet flue gas desulphurisation (FGD) system. The experimental evidence of the present work showed that Hg{sup 0} present in the gaseous phase can be dissolved and oxidized to a high degree (70-90%) by air together with SO{sub 3}{sup 2-} in wet FGD solutions. Transition metals such as Fe{sup 2+} and Mn{sup 2+} act as catalysts, chloride enhances the reaction, while some oxosulphur compounds, e.g. tetrathionate, inhibit the oxidation. A combination of several catalysts at a concentration of sulphite (SO{sub 3}{sup 2-}) below 100 mg L{sup -1} and an adequate redox potential of the solution can assure reasonable mercury removal even in the presence of oxidation inhibiting compounds. The main competitive reactions that govern final Hg{sup 0} removal in the FGD are as follows: (1) oxidation of Hg{sup 0} together with SO{sub 2} with air, enhanced by catalysts; (2) removal of catalysts by precipitation in the form of Fe(OH){sub 3} and eventually as MnO{sub 2} (to overcome this problem continuous addition of catalysts to the solution is required); (3) reduction of Fe{sup 3+} by tetrathionate to Fe{sup 2+} which (4) may reduce Hg{sup 2+} to Hg{sup 0} and probably (5) the complexation of Hg{sup 2+} by anions present which may play an important role in the mechanism by complexing the product(s) of the Hg{sup 0} oxidation reaction. 35 refs., 10 figs., 7 tabs.

  17. Atmospheric wet deposition of mercury and other trace elements in Pensacola, Florida

    Directory of Open Access Journals (Sweden)

    W. M. Landing

    2010-05-01

    Full Text Available In an effort to understand and quantify the impact of local, regional, and far-distant atmospheric mercury sources to rainfall mercury deposition in the Pensacola, Florida watershed, a program of event-based rainfall sampling was started in late 2004. Modified Aerochem-Metrics wet/dry rainfall samplers were deployed at three sites in the region around the Crist coal-fired power plant and event-based samples were collected continuously for three years. Samples were analyzed for total Hg and a suite of trace elements including Al, As, Ba, Bi, Cd, Ce, Co, Cr, Cs, Cu, Fe, Ga, La, Li, Mg, Mn, Na, Nb, Ni, P, Pb, Sb, Se, Si, Sn, Sr, Th, U, V, and Zn. Nutrients (ammonia and nitrate and major anions (chloride and sulfate were also measured on each sample. Multivariate statistical methods were used to sort these tracers into factors that represent potential source categories contributing to the rainfall chemistry. As, Hg, Sb, Se, Sn, and non sea-salt sulfate were all significantly correlated (R>0.6 with one factor which we interpret as an anthropogenic source term reflecting input from coal combustion throughout the southeastern US. Using ratios of total Hg to volatile elements, we estimate that 22–33% of the rainfall Hg results from coal combustion in the southeastern US with the majority coming from the global background.

  18. Bimodal variation in mercury wet deposition to the coastal zone of the southern Baltic

    Directory of Open Access Journals (Sweden)

    P. Siudek

    2009-10-01

    Full Text Available In the following periods: November 2005–June 2006 and October 2007–January 2009, concentrations and deposition rates of total mercury (THg and Hg(II were measured in precipitation over the urbanized and industrialized area of the southern Baltic – the city of Gdynia. Rains over the coastal zone had different concentrations of total mercury, they ranged from 8.6 to 118.0 ng L−1, out of which about 32% were labile, inorganic forms, easily reducible in a SnCl2 solution. Over the southern Baltic two maxima of concentrations were observed: first, in the heating season and second, in the non-heating season. Elevated concentrations of mercury in precipitations during heating seasons were the result of the activity of local emission sources (intensive combustion of fossil fuels in domestic furnaces and individual power and heat generating plants. During the warm season, precipitation over the southern Baltic could clean the air from Hg reemitted from sea and land surfaces. Precipitations, which purified marine and continental air masses were responsible for the comparable input of mercury to the coastal zone. The wet deposition value in 2008 was estimated to be 28.9 μg m−2. In the coastal zone of the southern Baltic, acid precipitations with the elevated Hg concentrations are very frequent.

  19. Mercury in stream water at five Czech catchments across a Hg and S deposition gradient

    Science.gov (United States)

    Navrátil, Tomáš; Shanley, James B.; Rohovec, Jan; Oulehle, Filip; Krám, Pavel; Matoušková, Šárka; Tesař, Miroslav; Hojdová, Maria

    2015-01-01

    The Czech Republic was heavily industrialized in the second half of the 20th century but the associated emissions of Hg and S from coal burning were significantly reduced since the 1990s. We studied dissolved (filtered) stream water mercury (Hg) and dissolved organic carbon (DOC) concentrations at five catchments with contrasting Hg and S deposition histories in the Bohemian part of the Czech Republic. The median filtered Hg concentrations of stream water samples collected in hydrological years 2012 and 2013 from the five sites varied by an order of magnitude from 1.3 to 18.0 ng L− 1. The Hg concentrations at individual catchments were strongly correlated with DOC concentrations r from 0.64 to 0.93 and with discharge r from 0.48 to 0.75. Annual export fluxes of filtered Hg from individual catchments ranged from 0.11 to 13.3 μg m− 2 yr− 1 and were highest at sites with the highest DOC export fluxes. However, the amount of Hg exported per unit DOC varied widely; the mean Hg/DOC ratio in stream water at the individual sites ranged from 0.28 to 0.90 ng mg− 1. The highest stream Hg/DOC ratios occurred at sites Pluhův Bor and Jezeří which both are in the heavily polluted Black Triangle area. Stream Hg/DOC was inversely related to mineral and total soil pool Hg/C across the five sites. We explain this pattern by greater soil Hg retention due to inhibition of soil organic matter decomposition at the sites with low stream Hg/DOC and/or by precipitation of a metacinnabar (HgS) phase. Thus mobilization of Hg into streams from forest soils likely depends on combined effects of organic matter decomposition dynamics and HgS-like phase precipitation, which were both affected by Hg and S deposition histories.

  20. 1987 wet deposition temporal and spatial patterns in North America

    Energy Technology Data Exchange (ETDEWEB)

    Simpson, J.C.; Olsen, A.R.

    1990-03-01

    The focus of this report is on North American wet deposition temporal patterns from 1979 to 1987 and spatial patterns for 1987. The report investigates the patterns of annual precipitation-weighted average concentration and annual deposition for nine ion species: hydrogen, sulfate, nitrate, ammonium, calcium, chloride, sodium, potassium, and magnesium. Data are from the Acid Deposition System (ADS) for the statistical reporting of North American deposition data which includes the National Atmospheric Deposition Program/National Trends Network (NADP/NTN), the MAP3S precipitation chemistry network, the Utility Acid Precipitation Study Program (UAPSP), the Canadian Precipitation Monitoring Network (CAPMoN), and the daily and 4-weekly Acidic Precipitation in Ontario Study (APIOS-D and APIOS-C). Mosaic maps, based on surface estimation using kriging, display concentration and deposition spatial patterns of pH, hydrogen, sulfate, nitrate, ammonium, and calcium ion species for 1987 annual, winter, and summer periods. The temporal pattern analyses use a subset of 39 sites over a 9-year (1979--1987) period and an expanded subset of 140 sites with greater spatial coverage over a 6-year (1982--1987) period. 68 refs., 15 figs., 15 tabs.

  1. Mass Dependent Fractionation of Hg Isotopes in Source Rocks, Mineral Deposits and Spring Waters of the California Coast Ranges, USA

    Science.gov (United States)

    Smith, C. N.; Kesler, S. E.; Blum, J. D.; Rytuba, J. J.

    2007-12-01

    We present here the first study of the isotopic composition of Hg in rocks, ore deposits, and active hydrothermal systems from the California Coast Ranges, one of Earth's largest Hg-depositing systems. The Franciscan Complex and Great Valley Sequence, which form the bedrock in the California Coast Ranges, are intruded and overlain by Tertiary volcanic rocks including the Clear Lake Volcanic Sequence. These rocks contain two types of Hg deposits, hot-spring deposits that form at shallow depths (geothermal systems that release Hg to the present surface. The Franciscan Complex and Great Valley Sequence contain clastic sedimentary rocks with higher concentrations of Hg than volcanic rocks of the Clear Lake Volcanic Field. Mean Hg isotope compositions for all three rock units are similar, although the range of values in Franciscan Complex rocks is greater than in either Great Valley or Clear Lake rocks. Hot spring and silica-carbonate Hg deposits have similar average isotopic compositions that are indistinguishable from averages for the three rock units, although δ202Hg values for the Hg deposits have a greater variance than the country rocks. Precipitates from dilute spring and saline thermal waters in the area have similarly large variance and a mean δ202Hg value that is significantly lower than the ore deposits and rocks. These observations indicate there is little or no isotopic fractionation during release of Hg from its source rocks into hydrothermal solutions. Isotopic fractionation does appear to take place during transport and concentration of Hg in deposits, especially in their uppermost parts. Boiling of hydrothermal fluids is likely the most important process causing of the observed Hg isotope fractionation. This should result in the release of Hg with low δ202Hg values into the atmosphere from the top of these hydrothermal systems and a consequent enrichment in heavy Hg isotopes in the upper crust through time.

  2. Anisotropic silver nanoparticles deposited on zeolite a for selective Hg2+ colorimetric sensing and antibacterial studies

    Directory of Open Access Journals (Sweden)

    Khorshidi Alireza

    2015-01-01

    Full Text Available Silver nanoparticles deposited on the surface of zeolite A were prepared via post ion-exchange reduction, and reduction-deposition methods. Formation of the silver nanoparticles on the surface of zeolite A was verified by surface plasmon spectra using diffuse reflectance spectroscopy and ultraviolet-visible spectroscopy. Morphology of the prepared samples was characterized by X-ray diffraction and scanning electron microscopy. Furthermore, silver nanoparticles deposited on the zeolite A, after fixation of Rhodamine B dye molecules over themselves, were successful in detecting Hg2+ ions selectively. After treatment with the so-obtained sensor, color change from colorless to pink was visible to the naked eye for the Hg2+ solution concentrations down to 1.0×10-8 mol.L-1. Antibacterial tests demonstrated the multifunctional application of the silver nanoparticles deposited on zeolite A.

  3. Precipitation chemistry and wet deposition in a remote wet savanna site in West Africa: Djougou (Benin)

    Science.gov (United States)

    Akpo, A. B.; Galy-Lacaux, C.; Laouali, D.; Delon, C.; Liousse, C.; Adon, M.; Gardrat, E.; Mariscal, A.; Darakpa, C.

    2015-08-01

    In the framework of the IDAF (IGAC/DEBITS/AFrica) international program, this study aims to study the chemical composition of precipitation and associated wet deposition at the rural site of Djougou in Benin, representative of a West and Central African wet savanna. Five hundred and thirty rainfall samples were collected at Djougou, Benin, from July 2005 to December 2009 to provide a unique database. The chemical composition of precipitation was analyzed for inorganic (Ca2+, Mg2+, Na+, NH4+, K+, NO3-, Cl-, SO42-) and organic (HCOO-, CH3COO-, C2H5COO-, C2O42-) ions, using ion chromatography. The 530 collected rain events represent a total of 5706.1 mm of rainfall compared to the measured pluviometry 6138.9 mm, indicating that the collection efficiency is about 93%. The order of total annual loading rates for soluble cations is NH4+ > Ca2+ > Mg2+ > K+. For soluble anions the order of loading is carbonates > HCOO- > NO3- > CH3COO- > SO4,SUP>2- > Cl- > C2O42- > C2H5COO-. In the wet savanna of Djougou, 86% of the measured pH values range between 4.7 and 5.7 with a median pH of 5.19, corresponding to a VWM (Volume Weighed Mean) H+ concentration of 6.46 μeq·L-1. This acidity results from a mixture of mineral and organic acids. The annual sea salt contribution was computed for K+, Mg2+, Ca2+ and SO42- and represents 4.2% of K+, 41% of Mg2+, 1.3% of Ca2+, and 7.4% of SO42-. These results show that K+, Ca2+, SO42-, and Mg2+ were mainly of non-marine origin. The marine contribution is estimated at 9%. The results of the chemical composition of rainwater of Djougou indicates that, except for the carbonates, ammonium has the highest VWM concentration (14.3 μeq·L-1) and nitrate concentration is 8.2 μeq·L-1. The distribution of monthly VWM concentration for all ions is computed and shows the highest values during the dry season, comparing to the wet season. Identified nitrogenous compound sources (NOx and NH3) are domestic animals, natural emissions from savanna soils

  4. Atmospheric wet deposition of mercury and other trace elements in Pensacola, Florida

    Directory of Open Access Journals (Sweden)

    W. M. Landing

    2009-12-01

    Full Text Available To understand and quantify the impact of local, regional, and distant atmospheric mercury sources to rainfall mercury deposition in the Pensacola, Florida watershed, a program of event-based rainfall sampling was started in late 2004. Modified Aerochem-Metrics wet/dry rainfall samplers were deployed at three sites in the region around the Crist coal-fired power plant and event-based samples were collected continuously for three years. Samples were analyzed for total mercury, volatile elements As, Se, and Sn, and a suite of trace elements including Al, Bi, Cd, Ce, Co, Cr, Cs, Cu, Dy, Er, Eu, Fe, Ho, Ga, Gd, La, Li, Lu, Mg, Mn, Na, Nb, Nd, Ni, P, Pb, Pr, Rb, Sb, Sc, Si, Sm, Sr, Tb, Th, Ti, Tm, U, V, Y, Yb, and Zn. Nutrients and major ions were also measured on each sample.

    Multivariate statistical methods are used to sort these tracers into factors that represent potential source components that contribute to the rainfall chemistry. Hg, As, Se, Sn, Sb, and non sea-salt sulfate were all significantly correlated with one anthropogenic factor. Using various Hg/element ratios, we can estimate that 22–33% of the rainfall mercury in the region results from coal combustion.

  5. The Kongsberg silver deposits, Norway: Ag-Hg-Sb mineralization and constraints for the formation of the deposits

    Science.gov (United States)

    Kotková, Jana; Kullerud, Kåre; Šrein, Vladimír; Drábek, Milan; Škoda, Radek

    2017-07-01

    The Kongsberg silver district has been investigated by microscopy and electron microprobe analysis, focusing primarily on the Ag-Hg-Sb mineralization within the context of the updated mineral paragenesis. The earliest mineralization stage is represented by sulfides, including acanthite, and sulfosalts. Native silver formed initially through breakdown of early Ag-bearing phases and later through influx of additional Ag-bearing fluids and silver remobilization. The first two generations of native silver were separated in time by the formation of Ni-Co-Fe sulfarsenides and the monoarsenide niccolite along rims of silver crystals. The presence of As-free sulfosalts and the absence of di- and tri-arsenides suggest a lower arsenic/sulfur activity ratio for the Kongsberg deposits compared to other five-element deposits. Native silver shows binary Ag-Hg and Ag-Sb solid solutions, in contrast to the ternary Ag-Hg-Sb compositions typical for other deposits of similar type. Antimonial silver together with allargentum, dyscrasite, and pyrargyrite was documented exclusively from the northern area of the district. Elsewhere, the only Sb-bearing minerals are polybasite and tetrahedrite/freibergite. Hg-rich silver (up to 21 wt% Hg) has been documented only in the central-western area. Myrmekite of freibergite and chalcopyrite reflects exsolution from an original Ag-poor tetrahedrite upon cooling, while myrmekite of pyrite and silver, forming through breakdown of low-temperature phases (argentopyrite or lenaite) upon heating, characterizes the Kongsberg silver district. Based on the stabilities of minerals and mineral assemblages, the formation of the silver mineralization can be constrained to temperatures between 180 and 250 °C.

  6. Changes in wet nitrogen deposition in the United States between 1985 and 2012

    NARCIS (Netherlands)

    Du, E.; Vries, de W.; Galloway, J.N.; Hu, X.; Fang, J.

    2014-01-01

    The United States (US) is among the global hotspots of nitrogen (N) deposition and assessing the temporal trends of wet N deposition is relevant to quantify the effectiveness of existing N regulation policies and its consequent environmental effects. This study analyzed changes in observed wet depos

  7. Atmospheric wet deposition of sulfur and nitrogen in Jiuzhaigou National Nature Reserve, Sichuan Province, China.

    Science.gov (United States)

    Qiao, Xue; Xiao, Weiyang; Jaffe, Daniel; Kota, Sri Harsha; Ying, Qi; Tang, Ya

    2015-04-01

    In the last two decades, remarkable ecological changes have been observed in Jiuzhaigou National Nature Reserve (JNNR). Some of these changes might be related to excessive deposition of sulfur (S) and nitrogen (N), but the relationship has not been quantified due to lack of monitoring data, particularly S and N deposition data. In this study, we investigated the concentrations, fluxes, and sources of S and N wet deposition in JNNR from April 2010 to May 2011. The results show that SO4(2-), NO3-, and NH4+ concentrations in the wet deposition were 39.4-170.5, 6.2-34.8, and 0.2-61.2 μeq L(-1), with annual Volume-Weighted Mean (VWM) concentrations of 70.5, 12.7, and 13.4 μeq L(-1), respectively. Annual wet deposition fluxes of SO4(2-), NO3-, and NH4+ were 8.06, 1.29, and 1.39 kg S(N)ha(-1), respectively, accounting for about 90% of annual atmospheric inputs of these species at the monitoring site. The results of Positive Matrix Factorization (PMF) analysis show that fossil fuel combustion, agriculture, and aged sea salt contributed to 99% and 83% of annual wet deposition fluxes of SO4(2-) and NO3-, respectively. Agriculture alone contributed to 89% of annual wet deposition flux of NH4+. Although wet deposition in JNNR was polluted by anthropogenic acids, the acidity was largely neutralized by the Ca2+ from crust and 81% of wet deposition samples had a pH higher than 6.00. However, acid rain mainly caused by SO4(2-) continued to occur in the wet season, when ambient alkaline dust concentration was lower. Since anthropogenic emissions have elevated S and N deposition and caused acid rain in JNNR, further studies are needed to better quantify the regional sources and ecological effects of S and N deposition for JNNR.

  8. RF magnetron sputtering deposition of CdTe passivation on HgCdTe

    Science.gov (United States)

    Rutkowski, Jaroslaw; Adamiec, Krzysztof; Rogalski, Antoni

    1998-04-01

    In this study, we report the RF magnetron sputtering growth and characterization of CdTe passivant on bulk n-type HgCdTe. Our investigations include the HgCdTe surface preparation and in-situ pretreatment, deposition-induced surface damage, interface charge, CdTe film stoichiometry, and thermal stability. The metal-insulator-semiconductor test structures are processed and their electrical properties are measured by capacitance-voltage characteristics. The heterostructures are also characterized by reflectance measurement. In order to investigate the passivation properties of CdTe/HgCdTe heterostructures, we have modeled the band diagram of abrupt CdTe/HgCdTe heterojunction. The effect of sputtering growth condition parameters is also reported. The sputtering CdTe layers, exhibit excellent dielectric, insulating and mechano- chemical properties, as well as interface properties. The interfaces are characterized by slight accumulation and a small hysteresis. A carefully controlled growth process and surface pretreatment tailored to the specific material are required in order to obtain near flat band conditions on n- type materials. Additional informations on surface limitations are obtained from analyzing the I-V characteristics of photodiodes with metal gates covering the p-n junction surface location.

  9. 3D modelling of transport, deposition and resuspension of highway deposited sediments in wet detention ponds.

    Science.gov (United States)

    Bentzen, T R

    2010-01-01

    The paper presents results from an experimental and numerical study of flows and transport of primarily particle bound pollutants in highway wet detention ponds. The study presented here is part of a general investigation on road runoff and pollution in respect to wet detention ponds. The objective is to evaluate the quality of long term simulation based on historical rains series of the pollutant discharges from roads and highways. A three-dimensional hydrodynamic and mud transport model is used for the investigation. The transport model has been calibrated and validated on e.g. experiments in a 30 m long concrete channel with width of 0.8 m and a water depth of approximately 0.8 m and in circular flume experiments in order to reproduce near-bed specific processes such as resuspension and consolidation. With a fairly good agreement with measurements, modelling of hydrodynamics, transport of dissolved pollutants and particles in wet detention ponds is possible with application of a three dimensional RANS model and the advection/dispersion equation taken physical phenomena like wind, waves, deposition, erosion and consolidation of the bottom sediment into account.

  10. Wet deposition of oxidized nitrogen in the United States Pacific Northwest for 2002

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This spatial data set was created by the U.S. Geological Survey (USGS) to represent the amount of wet deposition of oxidized nitrogen in the Pacific Northwest region...

  11. Inorganic Nitrogen Wet Deposition for the Conterminous United States, July 1955-June 1956

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Annual inorganic nitrogen wet deposition were estimated for the conterminous United States for July 1955 through June 1956. The estimates were derived from...

  12. Observations of atmospheric Hg species and depositions in remote areas of China

    Directory of Open Access Journals (Sweden)

    Feng X.

    2013-04-01

    Full Text Available From September 2007, we conducted continuous measurements of speciated atmospheric mercury (Hg and atmospheric mercury depositions at five remote sites in China. Four of these sites were involved in the Global Mercury Observation System (GMOS as ground-based stations. These stations were located in the northwest, southwest, northeast, and east part of China, respectively, which represent the regional atmospheric Hg budgets in different areas of China. The preliminary results showed that mean TGM concentrations were in the range of 1.60 – 2.88 ng m-3, with relatively higher levels observed at sites in Eastern China and Southwestern China and lower levels at sites in Northeastern and Northwestern China. TGM concentrations at remote sites of China were also higher than those reported from background sites in North America and Europe, and this is corresponding very well with the Chinese great anthropogenic Hg emissions. Gaseous oxidized mercury (GOM and particulate bounded mercury (PBM were in the ranges of 3.2 – 7.4 pg m−3 and 19.4 – 43.5 pg m-3, respectively. The preliminary result on precipitation showed mean precipitation THg concentrations were in the range of 2.7 – 18.0 ng L-1.

  13. Comparison of annual dry and wet deposition fluxes of selected pesticides in Strasbourg, France

    Energy Technology Data Exchange (ETDEWEB)

    Sauret, Nathalie [Marseilles University, Laboratoire Chimie Provence - UMR 6264, Campus Saint Charles, Case 29, 3 Place Victor Hugo, 13331 Marseilles Cedex 03 (France); Wortham, Henri [Marseilles University, Laboratoire Chimie Provence - UMR 6264, Campus Saint Charles, Case 29, 3 Place Victor Hugo, 13331 Marseilles Cedex 03 (France)], E-mail: Henri.Wortham@univ-provence.fr; Strekowski, Rafal [Marseilles University, Laboratoire Chimie Provence - UMR 6264, Campus Saint Charles, Case 29, 3 Place Victor Hugo, 13331 Marseilles Cedex 03 (France); Herckes, Pierre [Arizona State University, Department of Chemistry and Biochemistry, Tempe, AZ 85287-1604 (United States); Nieto, Laura Ines [Marseilles University, Laboratoire Chimie Provence - UMR 6264, Campus Saint Charles, Case 29, 3 Place Victor Hugo, 13331 Marseilles Cedex 03 (France)

    2009-01-15

    This work summarizes the results of a study of atmospheric wet and dry deposition fluxes of Deisopropyl-atrazine (DEA), Desethyl-atrazine (DET), Atrazine, Terbuthylazine, Alachlor, Metolachlor, Diflufenican, Fenoxaprop-p-ethyl, Iprodione, Isoproturon and Cymoxanil pesticides conducted in Strasbourg, France, from August 2000 through August 2001. The primary objective of this work was to calculate the total atmospheric pesticide deposition fluxes induced by atmospheric particles. To do this, a modified one-dimensional cloud water deposition model was used. All precipitation and deposition samples were collected at an urban forested park environment setting away from any direct point pesticide sources. The obtained deposition fluxes induced by atmospheric particles over a forested area showed that the dry deposition flux strongly contributes to the total deposition flux. The dry particle deposition fluxes are shown to contribute from 4% (DET) to 60% (cymoxanil) to the total deposition flux (wet + dry). - A modified one-dimensional cloud water deposition model is used to estimate the deposition fluxes of pesticides in the particle phase and compare the relative importance of dry and wet depositions.

  14. Photocatalytic oxidation removal of Hg0 using ternary Ag/AgI-Ag2CO3 hybrids in wet scrubbing process under fluorescent light

    Science.gov (United States)

    Zhang, Anchao; Zhang, Lixiang; Chen, Xiaozhuan; Zhu, Qifeng; Liu, Zhichao; Xiang, Jun

    2017-01-01

    A series of ternary Ag/AgI-Ag2CO3 photocatalysts synthesized using a facile coprecipitation method were employed to investigate their performances of Hg0 removal in a wet scrubbing reactor. The hybrids were characterized by N2 adsorption-desorption, XRD, SEM-EDS, HRTEM, XPS, DRS and ESR. The photocatalytic activities of Hg0 removal were evaluated under fluorescent light. The results showed that AgI content, fluorescent light irradiation, reaction temperature all showed significant influences on Hg0 removal. NO exhibited significant effect on Hg0 removal in comparison to SO2. Among these ternary Ag/AgI-Ag2CO3 hybrids, Ag/AgI(0.1)-Ag2CO3 showed the highest Hg0 removal efficiency, which could be ascribed to the effective separation of photogenerated electron-hole pairs between AgI and Ag2CO3 and the surface plasmon resonance (SPR) effect in the visible region by metallic silver nanoparticles (Ag0 NPs). The trapping studies of reactive radicals showed that the superoxide radicals (rad O2-) may play a key role in Hg0 removal under fluorescent light. According to the experimental and characterization results, a possible photocatalytic oxidation mechanism for enhanced Hg0 removal over Ag/AgI(0.1)-Ag2CO3 hybrid under fluorescent light was proposed.

  15. Atmospheric wet and dry deposition of trace elements at 10 sites in Northern China

    Science.gov (United States)

    Pan, Y. P.; Wang, Y. S.

    2015-01-01

    Atmospheric deposition is considered to be a major process that removes pollutants from the atmosphere and an important source of nutrients and contaminants for ecosystems. Trace elements (TEs), especially toxic metals deposited on plants and into soil or water, can cause substantial damage to the environment and human health due to their transfer and accumulation in food chains. Despite public concerns, quantitative knowledge of metal deposition from the atmosphere to ecosystems remains scarce. To advance our understanding of the spatiotemporal variations in the magnitudes, pathways, compositions and impacts of atmospherically deposited TEs, precipitation (rain and snow) and dry-deposited particles were collected simultaneously at 10 sites in Northern China from December 2007 to November 2010. The measurements showed that the wet and dry depositions of TEs in the target areas were orders of magnitude higher than previous observations within and outside China, generating great concern over the potential risks. The spatial distribution of the total (wet plus dry) deposition flux was consistent with that of the dry deposition, with a significant decrease from industrial and urban areas to suburban, agricultural and rural sites, while the wet deposition exhibited less spatial variation. In addition, the seasonal variation of wet deposition was also different from that of dry deposition, although they were both governed by the precipitation and emission patterns. For the majority of TEs that exist as coarse particles, dry deposition dominated the total flux at each site. This was not the case for potassium, nickel, arsenic, lead, zinc, cadmium, selenium, silver and thallium, for which the relative importance between wet and dry deposition fluxes varied by site. Whether wet deposition is the major atmospheric cleansing mechanism for the TEs depends on the size distribution of the particles. We found that atmospheric inputs of copper, lead, zinc, cadmium, arsenic and

  16. Episodic response project: Wet deposition at watersheds in three regions of the eastern United States

    Energy Technology Data Exchange (ETDEWEB)

    Barchet, W.R.

    1991-11-01

    During the period from August 1988 to June 1990, wet-only sampling of precipitation was carried out at three Episodic Response Project sites and at one supplemental site. The three watershed sites are Moss Lake, Biscuit Brook, and Linn Run. The supplemental site was the MAP3S site at Pennsylvania State University that characterizes the central group of northern Appalachian streams. The site operators adhered by varying degrees to the sample collection protocol based on the daily sampling protocol of the MAP3S Precipitation Chemistry Network. Sulfate and nitrate ion together accounted for more than 80% of total anions (in {mu}Eq/L) in the precipitation at all sites. Wet deposition of sulfate at Moss Lake, Biscuit Brook, Penn State, and Linn Run averaged 223, 230, 253, and 402 mg/m{sup 2}/month, respectively, whereas nitrate wet deposition averaged 197, 195, 160, and 233 mg/m{sup 2}/month, respectively. Sulfate deposition was a factor of 2 to 4 higher in summer than in winter. The seasonal pattern for nitrate deposition was weak; the seasonal contrast was less than a factor of 2.5 at all sites. The association between the wet deposition and precipitation chemistry at the MAP3S monitoring site and the average for the study watersheds was dependent on the distance between the site and watershed and the intervening terrain. Precipitation chemistry at the monitoring site is representative of that at the ERP study watersheds in the Adirondack and Catskill regions and in the south-western group of watersheds in the Appalachian region. High spatial variability in precipitation amounts makes this assumption weaker for wet deposition. Chemical input to watersheds from dry deposition has not been determined at any site but could range from a factor of 0.3 to 1.0 of the wet deposition. 7 refs., 38 figs., 12 tabs.

  17. Annual variations in wet-deposition chemistry related to changes in climate

    Science.gov (United States)

    Wetherbee, Gregory A.; Mast, M. Alisa

    2016-02-01

    National Atmospheric Deposition Program (NADP)/National Trends Network precipitation type, snow-season duration, and annual timing of selected chemical wet-deposition maxima vary with latitude and longitude within a 35-year (1979-2013) data record for the contiguous United States and Alaska. From the NADP data collected within the region bounded by 35.6645°-48.782° north latitude and 124°-68° west longitude, similarities in latitudinal and longitudinal patterns of changing snow-season duration, fraction of annual precipitation recorded as snow, and the timing of chemical wet-deposition maxima, suggest that the chemical climate of the atmosphere is linked to physical changes in climate. Total annual precipitation depth has increased 4-6 % while snow season duration has decreased from approximately 7 to 21 days across most of the USA, except in higher elevation regions where it has increased by as much as 21 days. Snow-season precipitation is increasingly comprised of snow, but annually total precipitation is increasingly comprised of liquid precipitation. Meanwhile, maximum ammonium deposition occurs as much as 27 days earlier, and the maximum nitrate: sulfate concentration ratio in wet-deposition occurs approximately 10-21 days earlier in the year. The maximum crustal (calcium + magnesium + potassium) cation deposition occurs 2-35 days earlier in the year. The data suggest that these shifts in the timing of atmospheric wet deposition are linked to a warming climate, but the ecological consequences are uncertain.

  18. Chemical Bath Deposition of PbS:Hg2+ Nanocrystalline Thin Films

    Directory of Open Access Journals (Sweden)

    R. Palomino-Merino

    2013-01-01

    Full Text Available Nanocrystalline PbS thin films were prepared by Chemical Bath Deposition (CBD at 40 ± 2°C onto glass substrates and their structural and optical properties modified by in-situ doping with Hg. The morphological changes of the layers were analyzed using SEM and the X-rays spectra showing growth on the zinc blende (ZB face. The grain size determined by using X-rays spectra for undoped samples was found to be ~36 nm, whereas with the doped sample was 32–20 nm. Optical absorption spectra were used to calculate the Eg, showing a shift in the range 1.4–2.4 eV. Raman spectroscopy exhibited an absorption band ~135 cm−1 displaying only a PbS ZB structure.

  19. Dispersion and dry and wet deposition of PAHs in an atmospheric environment.

    Science.gov (United States)

    Ozaki, N; Nitta, K; Fukushima, T

    2006-01-01

    The atmospheric concentration and dry and wet deposition were measured for particulate matter (PM) and polycyclic aromatic hydrocarbons (PAHs) from August to December in Higashi-Hiroshima City, Japan. PM concentration of fine particles (0.6-7 microm) was 5.7-75.1 micro m(-3), and coarse particles (> 7 microm) was 2.2-22.3 microg m(-3). Total PAHs concentration of fine particles was 0.14-16.3 ng m(-3), and coarse particles was 0.01-0.77 ng m(-3). Their concentration increased on non-rainy days and decreased rapidly on rainy days. For seasonal fluctuations of PAHs, their concentrations decreased from summer to winter, and the rate of decrease was more distinct for fine particles. For total (dry + wet) depositions, the PM flux was 1.9-11.2 mg m(-2) d(-1), and the total PAHs flux was 1.9-97.2 ng m(-3) d(-1). From these measurements, the yearly total loading of PAHs was estimated for the particle phase. Total loading was 28 microg m(-2) y(-1) for the dry deposition and 52 mg m(-2) y(-1) for the wet deposition. The loading of the wet deposition was comparable to those of the dry deposition for all ring numbers.

  20. Improved mapping of National Atmospheric Deposition Program wet-deposition in complex terrain using PRISM-gridded data sets.

    Science.gov (United States)

    Latysh, Natalie E; Wetherbee, Gregory Alan

    2012-01-01

    High-elevation regions in the United States lack detailed atmospheric wet-deposition data. The National Atmospheric Deposition Program/National Trends Network (NADP/NTN) measures and reports precipitation amounts and chemical constituent concentration and deposition data for the United States on annual isopleth maps using inverse distance weighted (IDW) interpolation methods. This interpolation for unsampled areas does not account for topographic influences. Therefore, NADP/NTN isopleth maps lack detail and potentially underestimate wet deposition in high-elevation regions. The NADP/NTN wet-deposition maps may be improved using precipitation grids generated by other networks. The Parameter-elevation Regressions on Independent Slopes Model (PRISM) produces digital grids of precipitation estimates from many precipitation-monitoring networks and incorporates influences of topographical and geographical features. Because NADP/NTN ion concentrations do not vary with elevation as much as precipitation depths, PRISM is used with unadjusted NADP/NTN data in this paper to calculate ion wet deposition in complex terrain to yield more accurate and detailed isopleth deposition maps in complex terrain. PRISM precipitation estimates generally exceed NADP/NTN precipitation estimates for coastal and mountainous regions in the western United States. NADP/NTN precipitation estimates generally exceed PRISM precipitation estimates for leeward mountainous regions in Washington, Oregon, and Nevada, where abrupt changes in precipitation depths induced by topography are not depicted by IDW interpolation. PRISM-based deposition estimates for nitrate can exceed NADP/NTN estimates by more than 100% for mountainous regions in the western United States.

  1. Improved mapping of National Atmospheric Deposition Program wet-deposition in complex terrain using PRISM-gridded data sets

    Science.gov (United States)

    Latysh, Natalie E.; Wetherbee, Gregory Alan

    2012-01-01

    High-elevation regions in the United States lack detailed atmospheric wet-deposition data. The National Atmospheric Deposition Program/National Trends Network (NADP/NTN) measures and reports precipitation amounts and chemical constituent concentration and deposition data for the United States on annual isopleth maps using inverse distance weighted (IDW) interpolation methods. This interpolation for unsampled areas does not account for topographic influences. Therefore, NADP/NTN isopleth maps lack detail and potentially underestimate wet deposition in high-elevation regions. The NADP/NTN wet-deposition maps may be improved using precipitation grids generated by other networks. The Parameter-elevation Regressions on Independent Slopes Model (PRISM) produces digital grids of precipitation estimates from many precipitation-monitoring networks and incorporates influences of topographical and geographical features. Because NADP/NTN ion concentrations do not vary with elevation as much as precipitation depths, PRISM is used with unadjusted NADP/NTN data in this paper to calculate ion wet deposition in complex terrain to yield more accurate and detailed isopleth deposition maps in complex terrain. PRISM precipitation estimates generally exceed NADP/NTN precipitation estimates for coastal and mountainous regions in the western United States. NADP/NTN precipitation estimates generally exceed PRISM precipitation estimates for leeward mountainous regions in Washington, Oregon, and Nevada, where abrupt changes in precipitation depths induced by topography are not depicted by IDW interpolation. PRISM-based deposition estimates for nitrate can exceed NADP/NTN estimates by more than 100% for mountainous regions in the western United States.

  2. Method development estimating ambient mercury concentration from monitored mercury wet deposition

    Directory of Open Access Journals (Sweden)

    S. M. Chen

    2013-05-01

    Full Text Available Speciated atmospheric mercury data have recently been monitored at multiple locations in North America; but the spatial coverage is far less than the long-established mercury wet deposition network. The present study describes a first attempt linking ambient concentration with wet deposition using Beta distribution fitting of a ratio estimate. The mean, median, mode, standard deviation, and skewness of the fitted Beta distribution parameters were generated using data collected in 2009 at 11 monitoring stations. Comparing the normalized histogram and the fitted density function, the empirical and fitted Beta distribution of the ratio shows a close fit. The estimated ambient mercury concentration was further partitioned into reactive gaseous mercury and particulate bound mercury using linear regression model developed by Amos et al. (2012. The method presented here can be used to roughly estimate mercury ambient concentration at locations and/or times where such measurement is not available but where wet deposition is monitored.

  3. Hg1-xCdxTe vapor deposition on CdZnTe substrates by Closed Space Sublimation technique

    Science.gov (United States)

    Rubio, Sandra; Sochinskii, Nikolai V.; Repiso, Eva; Tsybrii, Zinoviia; Sizov, Fiodor; Plaza, Jose Luis; Diéguez, Ernesto

    2017-01-01

    Closed Space Sublimation (CSS) technique has been studied to deposit Hg1-xCdxTe polycrystalline films on CdZnTe substrates at the improved pressure-temperature conditions. The experimental results on film characterization suggest that the CSS optimal conditions are the argon atmospheric pressure (1013 mbar) and the deposition temperature in the range of 500-550 °C. These conditions provide macro-defect free Hg1-xCdxTe films with the uniform size and surface distribution of polycrystals.

  4. Continental-scale variation in chloride/bromide ratios of wet deposition.

    Science.gov (United States)

    Short, M A; de Caritat, P; McPhail, D C

    2017-01-01

    Chlorine and bromine play crucial roles in atmospheric element cycles and are important environmental tracers in catchment investigations, so understanding their distribution at the Earth's near-surface is imperative for deciphering their behaviour. This study presents the first continental-scale analysis of Cl(-) and Br(-) concentrations of wet deposition, based on six and half years of weekly samples collected across North America. A recently developed imputation algorithm was applied to estimate the high proportion of censored Br(-) values, as well as the other eight analytes, based on the multivariate relationships of nine analytes. The results are consistent with previous studies that have found that the concentrations of these two ions in wet deposition, and the Cl(-)/Br(-) ratios of wet deposition decrease with distance inland. Close to the coast, Cl(-)/Br(-) ratios of wet deposition are similar to the ratio found in seawater (~288 by mass), rapidly decrease to approximately a third of the seawater ratio at ~200km inland, and then decrease at a much lesser rate to reach mass-ratios of 20 to 10 at ~1500km inland, following a logarithmic regression. The Niagara Falls and the Great Salt Lake are identified as localised sources of atmospheric solutes based on elevated Cl(-)/Br(-) ratios of wet deposition at proximal sites. Our observations provide further confidence in the findings presented in previous studies that have shown that Cl(-)/Br(-) ratios systematically decrease with increasing distance from the coast, despite the potential confounding impact of other processes, such as weather patterns, chemical behaviour and anthropogenic activity. Our results provide improved estimates of Cl(-)/Br(-) ratios of wet deposition source water in the absence of site-specific data.

  5. The chemical composition and fluxes of atmospheric wet deposition at four sites in South Africa

    Science.gov (United States)

    Conradie, E. H.; Van Zyl, P. G.; Pienaar, J. J.; Beukes, J. P.; Galy-Lacaux, C.; Venter, A. D.; Mkhatshwa, G. V.

    2016-12-01

    South Africa is the economic hub of southern Africa and is regarded as an important source region of atmospheric pollutants. A nitrogen dioxide (NO2) hotspot is clearly visible from space over the South African Mpumalanga Highveld, while South Africa is also regarded as the 9th largest anthropogenic sulphur (S) emitting country. Notwithstanding the importance of South Africa with regard to nitrogen (N) and S emissions, very limited data has been published on the chemical composition of wet deposition for this region. This paper presents the concentrations of sodium (Na+), ammonium (NH4+), potassium (K+), calcium (Ca2+), magnesium (Mg2+), nitrate (NO3-), chloride (Cl-), sulphate (SO42-) and water-soluble organic acids (OA) in the wet deposition samples collected between 2009 and 2014 at four South African IDAF (IGAC DEBITS Africa) sites, which are regarded as regional representatives of the north-eastern interior. Also, wet deposition fluxes of the ten ions are calculated and presented in this paper. The results show that the total ionic concentrations and fluxes of wet deposition were much higher at the two sites closer to anthropogenic emissions, while the pH of wet deposition at these two sites were lower compared to that of the two sites that were less impacted by anthropogenic emissions. . The major sources of the ten ions included marine, terrigenous (crust), fossil fuel combustion, agriculture and biomass burning. Significant contributions from fossil fuel combustion were determined for the two sites in close proximity to anthropogenic source regions. The results of back trajectory analysis, however, did indicate that the two remote sites are also affected by air masses passing over the source region through anti-cyclonic recirculation. The largest contributions at the two sites distant from the anthropogenic source regions were marine sources, while the impact of biomass burning was also more significant at the remote sites. Comparison to previous wet

  6. Atmospheric trace elements at Enewetak Atoll: 2. Transport to the ocean by wet and dry deposition

    Science.gov (United States)

    Arimoto, R.; Duce, R. A.; Ray, B. J.; Unni, C. K.

    1985-02-01

    The concentrations of trace elements in precipitation and dry deposition are presented for samples collected at Enewetak Atoll (11°N, 162° E) during SEAREX experiments in 1979. The concentrations of Al, Sc, Mn, Fe, Co, and Th in rain are dominated by crustal material, and for these elements, wet deposition evidently exceeds dry deposition. For most of these elements the present rates of atmospheric deposition at Enewetak are similar to their mean rate of accumulation in sediments over the past 5-10,000 years, suggesting that the air-to-sea exchange of particles is closely tied to the sedimentary cycle of the mid-Pacific. Noncrustal sources govern the concentrations of Pb, Zn, Cu, Se, and Cd in wet and dry deposition samples. Analyses of dry deposition collected from a flat plastic plate indicate that the amount of material recycled from the sea surface varies markedly between samples, and even though these estimates do not necessarily reflect the dry deposition to the ocean surface, the results suggest that recycled sea spray often amounts to more than 50% of the total dry deposition of the enriched elements. Recycled sea spray also makes up a significant fraction of the total wet deposition of the enriched elements. The net deposition rates of elements such as Cu and Zn are greater than or equal to their inputs from vertical mixing, but the net deposition of Pb clearly exceeds the input from upwelling. The current net deposition rates of the enriched elements are also similar to their rates of removal to sediments. These results indicate that air-sea exchange processes may significantly affect the chemistry of trace metals in the open ocean.

  7. Aldehyde concentrations in wet deposition and river waters

    Energy Technology Data Exchange (ETDEWEB)

    Dąbrowska, Agata, E-mail: agatadab@amu.edu.pl; Nawrocki, Jacek

    2013-05-01

    The process of pollutants removal from the atmosphere can be responsible for the appearance of aldehydes in surface waters. We observed that formaldehyde, acetaldehyde, propanal, glyoxal, methylglyoxal and acetone were commonly present in precipitations as well as in surface water samples, while semi-volatile and poorly soluble aldehydes as nonanal and decanal were observed seasonally. Particularly high level of carbonyls concentration was noted after periods of drought and at the beginning of rainy periods. We estimated that ca. 40% of aldehydes from wet precipitations were delivered into river waters. The level of carbonyl concentration in river was positively correlated with specific local meteorological conditions such as solar radiation and ozone concentration, in contrast, there was negative correlation between aldehyde concentration in the river samples and the precipitation intensity. - Highlights: ► Atmosphere pollutants are responsible for the appearance of aldehydes in surface waters. ► Volatile aldehydes are commonly present in precipitations as well as in surface waters. ► Semi-volatile and poorly soluble aldehydes as nonanal and decanal were observed seasonally. ► High concentration of carbonyls were noted after periods of drought and at the beginning of rain. ► Carbonyl concentration in river is correlated to meteorological conditions.

  8. Wet and dry nitrogen deposition in the central Sichuan Basin of China

    Science.gov (United States)

    Kuang, Fuhong; Liu, Xuejun; Zhu, Bo; Shen, Jianlin; Pan, Yuepeng; Su, Minmin; Goulding, Keith

    2016-10-01

    Reactive nitrogen (Nr) plays a key role in the atmospheric environment and its deposition has induced large negative impacts on ecosystem health and services. Five-year continuous in-situ monitoring of N deposition, including wet (total nitrogen (WTN), total dissolved nitrogen (WTDN), dissolved organic nitrogen (WDON), ammonium nitrogen (WAN) and nitrate nitrogen (WNN)) and dry (DNH3, DHNO3, DpNH4+, DpNO3- and DNO2) deposition, had been conducted since August 2008 to December 2013 (wet) and May 2011 to December 2013 (dry) in Yan-ting, China, a typical agricultural area in the central Sichuan Basin. Mean annual total N deposition from 2011 to 2013 was 30.8 kg N ha-1 yr-1, and speculated that of 2009 and 2010 was averaged 28.2 kg N ha-1 yr-1, respectively. Wet and dry N deposition accounted for 76.3% and 23.7% of annual N deposition, respectively. Reduced N (WAN, DNH3 and DpNH4+) was 1.7 times of oxidized N (WNN, DHNO3, DNO2 and DpNO3-) which accounted for 50.9% and 30.3% of TN, respectively. Maximum loadings of all N forms of wet deposition, gaseous NH3, HNO3 and particulate NH4+ in dry deposition occurred in summer and minimum loadings in winter. Whether monthly, seasonal or annual averaged, dissolved N accounted for more than 70% of the total. N deposition in the central Sichuan Basin increased during the sampling period, especially that of ammonium compounds, and has become a serious threat to local aquatic ecosystems, the surrounding forest and other natural or semi-natural ecosystems in the upper reaches of the Yangtze River.

  9. Oil sands development and its impact on atmospheric wet deposition of air pollutants to the Athabasca Oil Sands Region, Alberta, Canada.

    Science.gov (United States)

    Lynam, Mary M; Dvonch, J Timothy; Barres, James A; Morishita, Masako; Legge, Allan; Percy, Kevin

    2015-11-01

    Characterization of air pollutant deposition resulting from Athabasca oil sands development is necessary to assess risk to humans and the environment. To investigate this we collected event-based wet deposition during a pilot study in 2010-2012 at the AMS 6 site 30 km from the nearest upgrading facility in Fort McMurray, AB, Canada. Sulfate, nitrate and ammonium deposition was (kg/ha) 1.96, 1.60 and 1.03, respectively. Trace element pollutant deposition ranged from 2 × 10(-5) - 0.79 and exhibited the trend Hg < Se < As < Cd < Pb < Cu < Zn < S. Crustal element deposition ranged from 1.4 × 10(-4) - 0.46 and had the trend: La < Ce < Sr < Mn < Al < Fe < Mg. S, Se and Hg demonstrated highest median enrichment factors (130-2020) suggesting emissions from oil sands development, urban activities and forest fires were deposited. High deposition of the elements Sr, Mn, Fe and Mg which are tracers for soil and crustal dust implies land-clearing, mining and hauling emissions greatly impacted surrounding human settlements and ecosystems.

  10. Wet and dry deposition of atmospheric nitrogen at ten sites in Northern China

    Directory of Open Access Journals (Sweden)

    Y. P. Pan

    2012-01-01

    Full Text Available Emissions of reactive nitrogen (N species can affect surrounding ecosystems via atmospheric deposition. However, few long-term and multi-site measurements have focused on both the wet and the dry deposition of individual N species in large areas of Northern China. Thus, the magnitude of atmospheric deposition of various N species in Northern China remains uncertain. In this study, the wet and dry atmospheric deposition of different N species was investigated during a three-year observation campaign at ten selected sites in Northern China. The results indicate that N deposition levels in Northern China were high with a ten-site, three-year average of 60.6 kg N ha−1 yr−1. The deposition levels showed spatial and temporal variation in the range of 28.5–100.4 kg N ha−1 yr−1. Of the annual total deposition, 40% was deposited via precipitation, and the remaining 60% was comprised of dry-deposited forms. Compared with gaseous N species, particulate N species were not the major contributor of dry-deposited N; they contributed approximately 10% to the total flux. On an annual basis, oxidized species accounted for 21% of total N deposition, thereby implying that other forms of gaseous N, such as NH3, comprised a dominant portion of the total flux. The contribution of NO3 to N deposition was enhanced in certain urban and industrial areas. As expected, the total N deposition in Northern China was significantly larger than the values reported by national scale monitoring networks in Europe, North America and East Asia because of high rates of wet deposition and gaseous NH3 dry deposition. The results have three important implications. First, atmospheric N deposition in Northern China falls within the range of critical loads for temperate forests and grasslands, a threshold above which harmful ecological effects to specified parts of temperate ecosystems often

  11. The composition of wet deposition in El Paso, Texas

    Science.gov (United States)

    Emmert, Sonny

    The composition of precipitation reflects the transport of particles from varying air mass source regions as well as input from local environmental and anthropogenic activities. Air research in El Paso, TX, U.S.A/Ciudad Juarez, Chihuahua, Mexico has been traditionally limited to studies of local inputs of air pollution; no transition has been made to studying the scavenging, washout, and transport of pollutants by precipitation. The goal of this research project was to identify transported pollutants in precipitation, and determine if there were any health and ecological implications. The research investigated biological, chemical, and geological constituents in precipitation samples collected between September 2004 and October 2005. A variety of analysis techniques were used to determine composition of the precipitation. These techniques included bacterial and fungal plate counts, inductively coupled plasma/mass spectrometry, ion chromatography, transmission electron microscopy, scanning electron microscopy, and electron microprobe analysis. Samples were collected from an urban site in El Paso, Texas at the campus of the University of Texas at El Paso. Wet only samples were the target of the sample collection. Particulate matter <10 microns was correlated with fungal growth while particulate matter < 2.5 microns was correlated with bacterial growth in analyzed samples. Microscopy methods revealed new techniques in particle characterization, evidence of anthropogenic influence, and a wide variety of particle compositions. The ionic chemistry results reflected elevated levels of ions as well as an overall alkalinity of rainwater samples. Elemental analysis of the inorganic fraction suggested elevated enrichment of Phosphorus in the study area and possible ratios for transport identification of southwestern dust storms.

  12. 3D Modelling of Transport, Deposition and Resuspension of Highway Deposited Sediments in wet Detention Ponds

    DEFF Research Database (Denmark)

    Bentzen, Thomas Ruby

    2010-01-01

    The paper presents results from an experimental and numerical study of flows and transport of primarily particle bound pollutants in highway wet detention ponds. The study presented here is part of a general investigation on road runoff and pollution in respect to wet detention ponds. The objecti...

  13. Electrodes on a budget: Micropatterned electrode fabrication by wet chemical deposition

    OpenAIRE

    Ebina, Wataru; Rowat, Amy C; Weitz, David A.

    2009-01-01

    Precise patterning of metals is required for diverse microfluidic and microelectromechanical system (MEMS) applications ranging from the separation of proteins to the manipulation of single cells and drops of water-in-oil emulsions. Here we present a very simple, inexpensive method for fabricating micropatterned electrodes. We deposit a thin metal layer of controlled thickness using wet chemistry, thus eliminating the need for expensive equipment typically required for metal deposition. We de...

  14. Dry and wet deposition of polycyclic aromatic hydrocarbons and comparison with typical media in urban system of Shanghai, China

    Science.gov (United States)

    Wang, Qing; Liu, Min; Li, Ye; Liu, Yankun; Li, Shuwen; Ge, Rongrong

    2016-11-01

    Polycyclic aromatic hydrocarbons (PAHs) were studied in dry and wet deposition samples collected at urban and suburban sites of Shanghai, China from April 2014 to April 2015. Average wet deposition fluxes of PAHs were higher than dry deposition (62.6 ± 41.5 vs. 26.9 ± 14.4 μg/m2/day). However, dry deposition removed more PAHs than wet deposition (69% vs. 31%) due to much shorter durations of wet deposition. The highest dry and wet deposition fluxes were in fall and winter, respectively. The highest amount of dry deposition was in fall and the highest of wet deposition was in summer. The contribution of wet deposition to total deposited PAHs in Shanghai, East China was higher than that in northern China and lower than that in southern China. The difference can be explained by both precipitation amount and removal efficiency (washout ratio). Average dry deposition velocity and washout ratio of particle-associated PAHs were 5.2 cm/s and 5.8 × 104, respectively. Four sources of deposited PAHs were unraveled by positive matrix factorization (PMF) model: traffic, coal combustion, coking and volatilization, contributing 28.7%, 24.6%, 23.7% and 23.0%, respectively. More contribution of traffic and less coal combustion and volatilization were found at urban than at suburban site. As the connection between aerosol and surface soil, deposition had a different PAH composition from those in the two sides, containing more low MW PAHs. That arose the concern that dry deposition velocity and particle washout ratio could be overestimated if coarse particulate matter was excluded from the calculation. Although deposition has been considered as the predominant pathway of PAHs to urban surface system, the PAH composition in street dust differed drastically from that in deposition. This indicated that other sources (e.g. traffic) in urban system could have a greater contribution to PAHs than it had been identified in deposition samples.

  15. Temporal and spatial trends of chemical composition of wet deposition samples collected in Austria

    Science.gov (United States)

    Schreiner, Elisabeth; Kasper-Giebl, Anne; Lohninger, Hans

    2016-04-01

    Triggered by the occurrence of acid rain a sampling network for the collection of wet deposition samples was initiated in Austria in the early 1980s. Now the data set covers a time period of slightly more than 30 years for the stations being operable since the beginning. Sampling of rain water and snow was and is performed with Wet and Dry Only Samplers (WADOS) on a daily basis. Chemical analysis of rain water and snow samples comprised anions (chloride, nitrate, sulfate) and cations (sodium, ammonium, potassium, calcium and magnesium) as well as pH and electrical conductivity. Here we evaluate and discuss temporal trends of both, ion concentrations and wet deposition data for twelve sampling stations, which were operable for most of the observation period of 30 years. As expected concentrations and wet deposition loads of sulfate and acidity decreased significantly during the last three decades - which is also reflected by a strong decrease of sulfur emissions in Austria and neighboring countries. Regarding nitrate the decrease of concentrations and wet deposition loads is less pronounced. Again this is in accordance with changes in emission data. In case of ammonium even less stations showed a significant decrease of annual average concentrations and depositions. Reasons for that might be twofold. On one hand emissions of ammonia did not decrease as strongly as e.g. sulfur emissions. Furthermore local sources will be more dominant and can influence the year to year variability. Seasonality of ion concentrations and deposition loads were investigated using Fourier analysis. Sulfate, nitrate, ammonium, acidity and also precipitation amount showed characteristic seasonal patterns for most of the sites and for concentrations as well as deposition loads. However the maxima in ion concentrations and deposition loads were observed during different times of the year. Concentrations of basic cations and chloride, on the contrary, hardly showed any seasonality. However, as

  16. Modelling wet deposition in simulations of volcanic ash dispersion from hypothetical eruptions of Merapi, Indonesia

    Science.gov (United States)

    Dare, Richard A.; Potts, Rodney J.; Wain, Alan G.

    2016-10-01

    The statistical impact of including the process of wet deposition in dispersion model predictions of the movement of volcanic ash is assessed. Based on hypothetical eruptions of Merapi, Indonesia, sets of dispersion model simulations were generated, each containing four simulations per day over a period of three years, to provide results based on a wide range of atmospheric conditions. While on average dry sedimentation removes approximately 10% of the volcanic ash from the atmosphere during the first 24 h, wet deposition removes an additional 30% during seasons with highest rainfall (December and January) but only an additional 1% during August and September. The majority of the wet removal is due to in-cloud rather than below-cloud collection of volcanic ash particles. The largest uncertainties in the amount of volcanic ash removed by the process of wet deposition result from the choice of user-defined parameters used to compute the scavenging coefficient, and from the definition of the cloud top height. Errors in the precipitation field provided by the numerical weather prediction model utilised here have relatively less impact.

  17. Source-receptor relationship of wet and dry depositions of PAHs in Northeast Asia

    Science.gov (United States)

    Inomata, Yayoi; Kajino, Mizuo; Sato, Keiichi; Kurokawa, Junichi; Tang, Ning; Ohara, Toshimasa; Hayakawa, Kazuichi; Ueda, Hiromasa

    2016-04-01

    The spatial distribution of polycyclic aromatic hydrocarbons (PAHs) deposition by the source-receptor analysis over Northeast Asia was investigated by using an Eulerian regional-scale aerosol chemical model denoted as Regional Air Quality Model 2 for Persistent Organic Pollutants (RAQM2-POP version) at the year of 2005. We confirmed that the simulation was reproduced the PAH concentrations in precipitation based on comparison with observed and simulated concentrations. In this research, the domain was divided into six-source regions (Northern China, NCHN; Central China, CCHN; South China, SCHN; eastern Russia, ERUS; South Korea, SKOR; Japan, JPN) and three-receptor regions (Yellow Sea and East China Sea, ECS; the Sea of Japan, SOJ; northwestern Pacific Ocean, NWP). We focus on benzo[a]pyrene (BaP), which is the most carcinogenic species. The largest emission occurs on CCHN, following SCHN, NCHN, ERUS, SKOR, JPN. In the three Chinese domains and ERUS, the largest contribution to the dry and wet deposition is the domestic origin. In these domains, the wet deposition amount of BaP was 2-16 times larger than those of the dry deposition amount. The total deposition (wet+dry) amount was lower than those of the emission amount. In contrast, the total depositions are larger than the emissions from their own domains in the downwind region (SKOR, JPN), indicating a signature of long-range transport of PAH to the downwind regions. The relative contributions from the three Chinese domains and ERUS to the downwind region (KOR, JPN) are evaluated. For wet deposition in winter, the relative contribution from NCHN and CCHN (20-69%) are larger, whereas the relative contribution from CCHN, SCHN, RUS (13-57%) are larger in summer. These are controlled by the distribution of precipitation. For dry deposition, the relative contribution from NCHN and CCHN (28-49%) are large in winter season, whereas the relative contribution from the three Chinese domains and ERUS are decrease in summer

  18. Wet and dry atmospheric depositions of inorganic nitrogen during plant growing season in the coastal zone of Yellow River Delta.

    Science.gov (United States)

    Yu, Junbao; Ning, Kai; Li, Yunzhao; Du, Siyao; Han, Guangxuan; Xing, Qinghui; Wu, Huifeng; Wang, Guangmei; Gao, Yongjun

    2014-01-01

    The ecological problems caused by dry and wet deposition of atmospheric nitrogen have been widespread concern in the world. In this study, wet and dry atmospheric depositions were monitored in plant growing season in the coastal zone of the Yellow River Delta (YRD) using automatic sampling equipment. The results showed that SO4 (2-) and Na(+) were the predominant anion and cation, respectively, in both wet and dry atmospheric depositions. The total atmospheric nitrogen deposition was ~2264.24 mg m(-2), in which dry atmospheric nitrogen deposition was about 32.02%. The highest values of dry and wet atmospheric nitrogen deposition appeared in May and August, respectively. In the studied area, NO3 (-)-N was the main nitrogen form in dry deposition, while the predominant nitrogen in wet atmospheric deposition was NH4 (+)-N with ~56.51% of total wet atmospheric nitrogen deposition. The average monthly attribution rate of atmospheric deposition of NO3 (-)-N and NH4 (+)-N was ~31.38% and ~20.50% for the contents of NO3 (-)-N and NH4 (+)-N in 0-10 cm soil layer, respectively, suggested that the atmospheric nitrogen was one of main sources for soil nitrogen in coastal zone of the YRD.

  19. Wet Etching of Heat Treated Atomic Layer Chemical Vapor Deposited Zirconium Oxide in HF Based Solutions

    Science.gov (United States)

    Balasubramanian, Sriram; Raghavan, Srini

    2008-06-01

    Alternative materials are being considered to replace silicon dioxide as gate dielectric material. Of these, the oxides of hafnium and zirconium show the most promise. However, integrating these new high-k materials into the existing complementary metal-oxide-semiconductor (CMOS) process remains a challenge. One particular area of concern is the wet etching of heat treated high-k dielectrics. In this paper, work done on the wet etching of heat treated atomic layer chemical vapor deposited (ALCVD) zirconium oxide in HF based solutions is presented. It was found that heat treated material, while refractory to wet etching at room temperature, is more amenable to etching at higher temperatures when methane sulfonic acid is added to dilute HF solutions. Selectivity over SiO2 is still a concern.

  20. Increasing aeolian dust deposition to snowpacks in the Rocky Mountains inferred from snowpack, wet deposition, and aerosol chemistry

    Science.gov (United States)

    Clow, David W.; Williams, Mark W.; Schuster, Paul F.

    2016-12-01

    Mountain snowpacks are a vital natural resource for ∼1.5 billion people in the northern Hemisphere, helping to meet human and ecological demand for water in excess of that provided by summer rain. Springtime warming and aeolian dust deposition accelerate snowmelt, increasing the risk of water shortages during late summer, when demand is greatest. While climate networks provide data that can be used to evaluate the effect of warming on snowpack resources, there are no established regional networks for monitoring aeolian dust deposition to snow. In this study, we test the hypothesis that chemistry of snow, wet deposition, and aerosols can be used as a surrogate for dust deposition to snow. We then analyze spatial patterns and temporal trends in inferred springtime dust deposition to snow across the Rocky Mountains, USA, for 1993-2014. Geochemical evidence, including strong correlations (r2 ≥ 0.94) between Ca2+, alkalinity, and dust concentrations in snow deposited during dust events, indicate that carbonate minerals in dust impart a strong chemical signature that can be used to track dust deposition to snow. Spatial patterns in chemistry of snow, wet deposition, and aerosols indicate that dust deposition increases from north to south in the Rocky Mountains, and temporal trends indicate that winter/spring dust deposition increased by 81% in the southern Rockies during 1993-2014. Using a multivariate modeling approach, we determined that increases in dust deposition and decreases in springtime snowfall combined to accelerate snowmelt timing in the southern Rockies by approximately 7-18 days between 1993 and 2014. Previous studies have shown that aeolian dust emissions may have doubled globally during the 20th century, possibly due to drought and land-use change. Climate projections for increased aridity in the southwestern U.S., northern Africa, and other mid-latitude regions of the northern Hemisphere suggest that aeolian dust emissions may continue to increase

  1. Temporal and spatial patterns in the chemistry of wet deposition in Southern Alps

    Science.gov (United States)

    Rogora, M.; Colombo, L.; Marchetto, A.; Mosello, R.; Steingruber, S.

    2016-12-01

    In the last decades, in Europe a large effort was carried out to reduce sulphur and nitrogen emission in the atmosphere, in order to improve air quality and reduce the acidity of atmospheric deposition and the amount of nitrogen compounds it carries to terrestrial and aquatic ecosystems. This resulted in a sharp decrease in the deposition of sulphate and acidity, while until recently a decrease of the atmospheric load of nitrogen compounds was not evident. In this paper, we focus on the subalpine and alpine areas in North-Western Italy and Southern Switzerland (Canton Ticino), receiving high deposition of atmospheric pollutants transported from emission sources in the Po Valley, one of the most urbanised and industrialised areas of Europe. Long-term studies, covering a 30-year period (1984-2014), were carried out on the chemistry of atmospheric deposition in this area and its effects on surface water bodies through a cooperation between Swiss and Italian research institutions. A total of 14 atmospheric deposition wet-only sampling sites operate in this area, covering a wide latitudinal and altitudinal range (about 200-1900 m a.s.l.). A spatial gradient in the deposition of sulphate and nitrogen compounds was evident both in the 1990s and in recent times (2008-2012), with highest values in the south-eastern part of the area, close to the major emission sources. Deposition also varied depending on local topography. The analysis of long-term trends revealed a large proportion of significant decreasing trends in the concentration of both sulphate and nitrogen compounds. Deposition changes were less evident, due to the high interannual variability in the data, caused by the highly variable precipitation amount, ranging from 1200-1300 mm in dry years to 3000 mm in wet years. Sulphate concentrations and deposition decreased steadily since the 1980s, while ammonium and nitrate showed a widespread decrease only in the most recent period (after 2006). However, nitrogen wet

  2. Sensitivity study of the wet deposition schemes in the modelling of the Fukushima accident.

    Science.gov (United States)

    Quérel, Arnaud; Quélo, Denis; Roustan, Yelva; Mathieu, Anne; Kajino, Mizuo; Sekiyama, Thomas; Adachi, Kouji; Didier, Damien; Igarashi, Yasuhito

    2016-04-01

    The Fukushima-Daiichi release of radioactivity is a relevant event to study the atmospheric dispersion modelling of radionuclides. Actually, the atmospheric deposition onto the ground may be studied through the map of measured Cs-137 established consecutively to the accident. The limits of detection were low enough to make the measurements possible as far as 250km from the nuclear power plant. This large scale deposition has been modelled with the Eulerian model ldX. However, several weeks of emissions in multiple weather conditions make it a real challenge. Besides, these measurements are accumulated deposition of Cs-137 over the whole period and do not inform of deposition mechanisms involved: in-cloud, below-cloud, dry deposition. A comprehensive sensitivity analysis is performed in order to understand wet deposition mechanisms. It has been shown in a previous study (Quérel et al, 2016) that the choice of the wet deposition scheme has a strong impact on the assessment of the deposition patterns. Nevertheless, a "best" scheme could not be highlighted as it depends on the selected criteria: the ranking differs according to the statistical indicators considered (correlation, figure of merit in space and factor 2). A possibility to explain the difficulty to discriminate between several schemes was the uncertainties in the modelling, resulting from the meteorological data for instance. Since the move of the plume is not properly modelled, the deposition processes are applied with an inaccurate activity in the air. In the framework of the SAKURA project, an MRI-IRSN collaboration, new meteorological fields at higher resolution (Sekiyama et al., 2013) were provided and allows to reconsider the previous study. An updated study including these new meteorology data is presented. In addition, a focus on several releases causing deposition in located areas during known period was done. This helps to better understand the mechanisms of deposition involved following the

  3. Assessment of dry and wet atmospheric deposits of radioactive aerosols: application to Fukushima radiocaesium fallout.

    Science.gov (United States)

    Gonze, Marc-André; Renaud, Philippe; Korsakissok, Irène; Kato, Hiroaki; Hinton, Thomas G; Mourlon, Christophe; Simon-Cornu, Marie

    2014-10-07

    The Fukushima Dai-ichi nuclear accident led to massive atmospheric deposition of radioactive substances onto the land surfaces. The spatial distribution of deposits has been estimated by Japanese authorities for gamma-emitting radionuclides through either airborne monitoring surveys (since April 2011) or in situ gamma-ray spectrometry of bare soil areas (since summer 2011). We demonstrate that significant differences exist between the two surveys for radiocaesium isotopes and that these differences can be related to dry deposits through the use of physically based relationships involving aerosol deposition velocities. The methodology, which has been applied to cesium-134 and cesium-137 deposits within 80-km of the nuclear site, provides reasonable spatial estimations of dry and wet deposits that are discussed and compared to atmospheric numerical simulations from the Japanese Atomic Energy Agency and the French Institute of Radioprotection and Nuclear Safety. As a complementary approach to numerical simulations, this field-based analysis has the possibility to contribute information that can be applied to the understanding and assessment of dose impacts to human populations and the environment around Fukushima.

  4. Wet deposition of mercury in the U.S. and Canada, 1996-2005: Results and analysis of the NADP mercury deposition network (MDN)

    Science.gov (United States)

    Prestbo, Eric M.; Gay, David A.

    One of the most critical measurements needed to understand the biogeochemical cycle of mercury, and to verify atmospheric models, is the rate of mercury wet-deposition. The Mercury Deposition Network (MDN) operates sites across North America to monitor total mercury in wet-deposition. MDN's primary goal is to provide both spatial and temporal continental-scale observations of mercury wet-deposition fluxes to support researchers, modelers, policy-makers and the public interest. MDN represents the only continental-scale mercury deposition database with a >10-year record of continuous values. This study provides analysis and interpretation of MDN observations at 10 years (1996-2005) with an emphasis on investigating whether rigorous, statistically-significant temporal trends and spatial patterns were present and where they occurred. Wet deposition of mercury ranges from more than 25 μg m -2 yr in south Florida to less than 3 μg m -2 yr in northern California. Volume-weighted total mercury concentrations are statistically different between defined regions overall (Southeast ≈ Midwest > Ohio River > Northeast), with the highest in Florida, Minnesota, and several Southwest locations (10-16 ng L -1). Total mercury wet-deposition is significantly different between defined regions (Southeast > Ohio River > Midwest > Northeast). Mercury deposition is strongly seasonal in eastern North America. The average mercury concentration is about two times higher in summer than in winter, and the average deposition is approximately more than three times greater in summer than in winter. Forty-eight sites with validated datasets of five years or more were tested for trends using the non-parametric seasonal Kendall trend test. Significant decreasing mercury wet-deposition concentration trends were found at about half of the sites, particularly across Pennsylvania and extending up through the Northeast.

  5. Wet and dry atmospheric deposition on TiO{sub 2} coated glass

    Energy Technology Data Exchange (ETDEWEB)

    Chabas, Anne, E-mail: anne.chabas@lisa.univ-paris12.f [Laboratoire Interuniversitaire des Systemes Atmospheriques, Universite Paris 12, Universite Paris 7, CNRS, 61 avenue du General de Gaulle, 94010 Creteil (France); Gentaz, Lucile; Lombardo, Tiziana; Sinegre, Romain [Laboratoire Interuniversitaire des Systemes Atmospheriques, Universite Paris 12, Universite Paris 7, CNRS, 61 avenue du General de Gaulle, 94010 Creteil (France); Falcone, Roberto [Stazione Sperimentale del Vetro, Calle Briati 10, 30141 Murano, Venezia (Italy); Verita, Marco [Laboratorio di Analisi dei Materiali Antichi LAMA, Universita IUAV di Venezia, S. Polo 2648, 30125 Venezia (Italy); Cachier, Helene [Laboratoire des Sciences du Climat et de l' Environnement, CNRS-CEA, Orme des Merisiers, bat 701, 91191Gif sur Yvette (France)

    2010-12-15

    To prevent the soiling of glass window used in the built environment, the use TiO{sub 2} coated products appears an important application matter. To test the cleaning efficiency and the sustainability of self-cleaning glass, a field experiment was conducted under real life condition, on a site representative of the background urban pollution. Samples of float glass, used as reference, and commercialized TiO{sub 2} coated glasses were exposed to dry and wet atmospheric deposition during two years. The crossed optical, chemical and microscopic evaluations performed, after withdrawal, allowed highlighting a sensible difference between the reference and the self-cleaning substrate in terms of accumulation, nature, abundance and geometry of the deposit. This experiment conducted in real site emphasized on the efficacy of self-cleaning glass to reduce the maintenance cost. - This paper evaluates the self-cleaning glass efficiency highlighting its ability to prevent soiling and to be used as a mean of remediation.

  6. On the wetting behavior of ceria thin films grown by pulsed laser deposition

    Science.gov (United States)

    Fu, Sin-Pui; Rossero, Jorge; Chen, Chen; Li, Daniel; Takoudis, Christos G.; Abiade, Jeremiah T.

    2017-02-01

    Polymers are most widely used in the production of water-repellant coatings. However, their use in applications requiring wear resistance or high-temperature stability is extremely limited. A recent report suggests that wear resistant, thermally stable rare earth oxide materials like cerium dioxide (ceria) are intrinsically water repellant. We have studied this intriguing finding for ceria thin films fabricated by pulsed laser deposition (PLD) at different oxygen pressures and different substrate temperatures. We used a custom apparatus for measuring water contact angles on ceria films deposited by PLD. X-ray photoelectron spectroscopy was used to determine the relationship between the ceria wetting behavior and ceria surface chemistry. Our results show that ceria thin films are intrinsically hydrophilic and that hydrophobicity arises due to adsorption of hydrocarbon species after ˜24 h.

  7. Passivation Effect of Atomic Layer Deposition of Al2O3 Film on HgCdTe Infrared Detectors

    Science.gov (United States)

    Zhang, Peng; Ye, Zhen-Hua; Sun, Chang-Hong; Chen, Yi-Yu; Zhang, Tian-Ning; Chen, Xin; Lin, Chun; Ding, Ring-Jun; He, Li

    2016-09-01

    The passivation effect of atomic layer deposition of (ALD) Al2O3 film on a HgCdTe infrared detector was investigated in this work. The passivation effect of Al2O3 film was evaluated by measuring the minority carrier lifetime, capacitance versus voltage ( C- V) characteristics of metal-insulator-semiconductor devices, and resistance versus voltage ( R- V) characteristics of variable-area photodiodes. The minority carrier lifetime, C- V characteristics, and R- V characteristics of HgCdTe devices passivated by ALD Al2O3 film was comparable to those of HgCdTe devices passivated by e-beam evaporation of ZnS/CdTe film. However, the baking stability of devices passivated by Al2O3 film is inferior to that of devices passivated by ZnS/CdTe film. In future work, by optimizing the ALD Al2O3 film growing process and annealing conditions, it may be feasible to achieve both excellent electrical properties and good baking stability.

  8. Global cloud and precipitation chemistry and wet deposition: tropospheric model simulations with ECHAM5/MESSy1

    Directory of Open Access Journals (Sweden)

    J. Lelieveld

    2007-05-01

    Full Text Available The representation of cloud and precipitation chemistry and subsequent wet deposition of trace constituents in global atmospheric chemistry models is associated with large uncertainties. To improve the simulated trace gas distributions we apply the new submodel SCAV, which includes detailed cloud and precipitation chemistry and present results of the atmospheric chemistry general circulation model ECHAM5/MESSy1. A good agreement with observed wet deposition fluxes for species causing acid rain is obtained. The new scheme enables prognostic calculations of the pH of clouds and precipitation, and these results are also in accordance with observations. We address the influence of detailed cloud and precipitation chemistry on trace constituents based on sensitivity simulations. The results confirm previous results from regional scale and box models, and we extend the analysis to the role of aqueous phase chemistry on the global scale. Some species are directly affected through multiphase removal processes, and many also indirectly through changes in oxidant concentrations, which in turn have an impact on the species lifetime. While the overall effect on tropospheric ozone is relatively small (3 can reach ≈20%, and several important compounds (e.g., H2O2, HCHO are substantially depleted by clouds and precipitation.

  9. Optimisation of wet chemical silane deposition to improve the interfacial strength of stainless steel/epoxy

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Amit Kumar, E-mail: aghosh@vub.ac.be [Research group of Physical Chemistry and Polymer Science, Vrije Universiteit Brussel (VUB), Pleinlaan 2, B-1050 Brussels (Belgium); Bertels, Ellen; Goderis, Bart; Smet, Mario [Polymer Chemistry and Materials, KU Leuven, Celestijnenlaan 200f-box 2404, B-3001 Heverlee (Belgium); Van Hemelrijck, Danny [Department of Mechanics of Materials and Constructions, Vrije Universiteit Brussel (VUB), Pleinlaan 2, B-1050 Brussels (Belgium); Van Mele, Bruno [Research group of Physical Chemistry and Polymer Science, Vrije Universiteit Brussel (VUB), Pleinlaan 2, B-1050 Brussels (Belgium)

    2015-01-01

    Highlights: • γ-aminopropyltriethoxysilane (APS) wet surface treatment was evaluated to improve the interfacial strength of stainless steel/epoxy hybrid. • The applied methodology seems to be of major importance. • A doubling of the interfacial strength compared to non-treated samples is observed. • The obtained fracture strength value of more than 60 MPa by far exceeds values currently found in literature and approaches the epoxy fracture strength. - Abstract: The evaluation of various wet chemical deposition conditions of γ-aminopropyltriethoxysilane (APS) on stainless steel resulted in stainless steel/epoxy hybrids with improved interfacial strength. Nuclear magnetic resonance spectroscopy (NMR) revealed the working window of the silane solution used, while scanning electron microscopy (SEM) and spectroscopic ellipsometry (SE) served at characterising the final APS film structural properties. With pull-off testing the interfacial strength of surface treated steel plates in contact with an epoxy resin was determined. Fracture surface morphological features allowed identifying the failure mode. Optimisation of the different silane deposition conditions led to a doubling of the interfacial strength compared to non-treated samples. The fracture strength value of more than 60 MPa by far exceeds values currently found in literature and approaches the epoxy fracture strength by which the original adhesive failure mode converts into a more cohesive failure mode.

  10. Wet deposition of hydrocarbons in the city of Tehran-Iran.

    Science.gov (United States)

    Zahed, Mohammad Ali; Pardakhti, Alireza; Mohajeri, Leila; Bateni, Farshid

    2010-06-01

    Air pollution in the city of Tehran has been a major problem for the past three decades. The direct effects of hydrocarbon contaminants in the air are particularly important such as their carcinogenic, mutagenic, and teratogenic effects which can be transported to other environments via dry and wet deposition. In the present study, rainwater samples were collected and analyzed for 16 polycyclic aromatic hydrocarbons (PAHs), benzene, toluene, ethyl benzene, and xylene (BTEX) as well as fuel fingerprints in two ranges of gasoline (C5-C11) and diesel fuel (C12-C20) using a gas chromatograph equipped with a flame ionization detector (GC/FID). Mean concentrations of summation operator16 PAHs varied between 372 and 527 microg/L and for BTEX was between 87 and 188 microg/L with maximum of 36 microg/L for toluene. Both gasoline range hydrocarbons (GRH) and diesel range hydrocarbons (DRH) were also present in the collected rainwater at concentrations of 190 and 950 microg/L, respectively. Hydrocarbon transports from air to soil were determined in this wet deposition. Average hydrocarbon transportation for summation operatorPAHs, BTEX, GRH, and DRH was 2,747, 627, 1,152, and 5,733 microg/m(2), respectively.

  11. Global cloud and precipitation chemistry and wet deposition: tropospheric model simulations with ECHAM5/MESSy1

    Directory of Open Access Journals (Sweden)

    H. Tost

    2007-01-01

    Full Text Available The representation of cloud and precipitation chemistry and subsequent wet deposition of trace constituents in global atmospheric chemistry models is associated with large uncertainties. To improve the simulated trace gas distributions we apply the new submodel SCAV, which includes detailed cloud and precipitation chemistry and present results of the atmospheric chemistry general circulation model ECHAM5/MESSy1. A good agreement with observed wet deposition fluxes for species causing acid rain is obtained. The new scheme enables prognostic calculations of the pH of clouds and precipitation, and these results are also in accordance with observations. We address the influence of detailed cloud and precipitation chemistry on trace constituents based on sensitivity simulations. The results confirm previous results from regional scale and box models, and we extend the analysis to the role of aqueous phase chemistry on the global scale. Some species are directly affected through multiphase removal processes, and many also indirectly through changes in oxidant concentrations, which in turn have an impact on the species lifetime. While the overall effect on tropospheric ozone is relatively small (<10%, regional effects on O3 can reach ~20%, and several important compounds (e.g., H2O2, HCHO are substantially depleted by clouds and precipitation.

  12. [Chemical Characteristics of Atmospheric Wet Deposition in Winter and Its Forestry Canopy Interception Mechanism in Red Soil Hilly Area].

    Science.gov (United States)

    Hao, Zhuo; Gao, Yang; Zhang, Jin-zhong; Yu, Gui-rui

    2015-12-01

    In order to disclose the interception mechanism of forestry canopy to atmospheric wet deposition, the concentrations of nutrients (C, N, P, S) and trace elements (K, Ca, Na, Mg, Al, Fe, Mn, Zn) in wet deposition and through fall in winter were monitored in Subtropical Qiananzhou basin. The results showed that the wet deposition in this area was mainly acid deposition, the pH of which ranged from 3.49 to 7.0. The major components of wet deposition were nitrate (NO₃⁻) and sulfate ions (SO₄²⁻), the monthly average deposition fluxes of which were 4.68 kg · hm⁻² and 0.36 kg · hm⁻², and trace elements (Zn, K, Ca) with monthly average deposition fluxes of 1.72, 0.56 and 0.36 kg · hm⁻², respectively. Non-metallic nutrients such as dissolved organic carbon (DOC) , dissolved total nitrogen (DTN), total phosphorus (TP), Ca, Mg and Mn were easy to leach, the dilution rate could reach up to 64.69%, 206.75%, 301.38%, 137.94%, 405.25% and 1226.60%, respectively. Moreover, the Zn and sulfate ion (SO₄²⁻) could be well absorbed by forests canopy, the absorption proportions of which were 73.50% and 12.51%, respectively.

  13. Atmospherically-promoted photosynthetic activity in a well-mixed ecosystem: Significance of wet deposition events of nitrogen compounds

    OpenAIRE

    2006-01-01

    Wet atmospheric deposition of dissolved N, P and Si species is studied in well-mixed coastal ecosystem to evaluate its potential to stimulate photosynthetic activities in nutrient-depleted conditions. Our results show that, during spring, seawater is greatly depleted in major nutrients: Dissolved Inorganic Nitrogen (DIN), Dissolved Inorganic Phosphorus (DIP) and Silicic acid (Si), in parallel with an increase of phytoplanktonic biomass. In spring (March-May) and summer (June-September), wet a...

  14. Airmass Trajectories and Long Range Transport of Pollutants: Review of Wet Deposition Scenario in South Asia

    Directory of Open Access Journals (Sweden)

    Umesh Kulshrestha

    2014-01-01

    Full Text Available This paper presents a review of airmass trajectories and their role in air pollution transport. It describes the concept, history, and basic calculation of air trajectories citing various trajectory models used worldwide. It highlights various areas of trajectory applications and errors associated with trajectory calculations. South Asian region receives airmasses from Europe, Middle East, Africa, and Indian Ocean, and so forth, depending upon the season. These airmasses are responsible for export and import of pollutants depositing in nearby states. Trajectory analysis revealed that soil is contributed by the dust storms coming from Oman through Gulf and Iran, while most of black carbon (BC sources are located in India. A detailed review of trajectories associated with wet deposition events indicated that airmasses coming from Europe and Middle East carry high concentration of acidic pollutants which are deposited in Himalayan ranges. Similarly, trajectory analysis revealed that acidic pollutants from continental anthropogenic sources are transported to an ecosensitive site in Western Ghats in India and the outward fluxes of anthropogenic activities of Indo-Gangetic region are transported towards Bay of Bengal. Hence, transboundary and long range transport of pollutants are very important issues in South Asia which need immediate attention of scientists and policy makers.

  15. Isotopic Composition of Gaseous Elemental Mercury (Hg0) at Various Sites in Japan

    Science.gov (United States)

    Yamakawa, A.; Moriya, K.; Yoshinaga, J.

    2015-12-01

    Mercury (Hg) is a toxic heavy metal, which exists in various chemical forms in the environmental system. In the atmosphere, Hg exists in three forms (Hg0(g), Hg+2(g), and Hg(p)). Hg0(g) is the dominant species of atmospheric Hg, accounting for >95% of the total Hg in the atmosphere. Because Hg0(g) is highly volatile and has limited solubility in water, it cannot be easily removed by wet or dry deposition processes. Therefore, the residence time of Hg0(g) in the atmosphere is relatively long (1 to 2 years), allowing long-range transport from mercury emission source(s). Conversely, Hg+2(g) and Hg(p) are effectively removed from the atmosphere through wet and dry depositions. The determination of mercury source attribution using quantitative data is challenging because Hg0(g) may be deposited on an area upon oxidation to Hg+2(g) and associated with aerosols and particulates to form Hg(p) while the global cycling of Hg0(g). Over the last decade, the development of analytical methods of highly precise Hg isotopic measurements demonstrated mass-dependent fractionation (MDF) and mass-independent fractionation (MIF) of Hg isotopes in environmental samples. For instance, MDF of Hg isotopes is thought to occur during various natural and industrial Hg transformations. MIF of Hg isotopes is observed during abiotic reduction, photochemical and non-photochemical, and physical and chemical processes. Such processes lead to differences in the Hg isotopic composition of different emission sources, both natural and anthropogenic, and atmospheric processes (i.e., transportation, oxidation/reduction, deposition, and reemission). Therefore, Hg isotopic compositions could be used to trace the sources and processes of atmospheric Hg. For securing the reliability and accuracy of atmospheric Hg isotope data, the methods of collection, pretreatment, and isotopic measurement for Hg0(g) were developed to obtain high recovery yield of samples with no Hg isotopic fractionation during each

  16. Reduction of Hg1 - xCdxTe native oxide during the SiNx deposition process

    Science.gov (United States)

    Sudo, G.; Kajihara, N.; Miyamoto, Y.; Tanikawa, K.

    1987-11-01

    Electron cyclotron resonance plasma chemical vapor deposition enables low-temperature SiNx deposition on Hg1-xCdxTe (MCT). The SiNx film has an excellent interface on MCT with a low surface state density of 1.0×1011 cm-2 eV-1 and a low fixed charge of -1.4×1011 cm-2. A detailed analysis by x-ray photoelectron spectroscopy and Auger electron spectroscopy spectra of Te, Cd, and Si at the SiNx/MCT interface indicated that the SiNx deposition reduces the naturally grown MCT native oxide. The oxygen taken from Te oxidizes SiH4 and produces silicon oxides which remain in the SiNx film. Since a chemical shift caused by oxidized Cd at the fresh surface of MCT is very slight, intentionally oxidized samples were used to confirm the above reaction. The analysis of the shape of the Si(2p) peak at the interface indicated that the silicon oxides are composed of SiO and SiO2. Thermodynamic considerations support such a mechanism.

  17. Control over the preferred orientation of CIGS films deposited by magnetron sputtering using a wetting layer

    Science.gov (United States)

    Yan, Yong; Jiang, Fan; Liu, Lian; Yu, Zhou; Zhang, Yong; Zhao, Yong

    2016-01-01

    A growth method is presented to control the preferred orientation in chalcopyrite CuIn x Ga1- x Se2 (CIGS) thin films grown by magnetron sputtering. Films with (220/204) and (112) preferred orientation as well as randomly oriented films were prepared. The effects of an In2Se3 wetting layer and the working pressure on the texture transition phenomena were examined. A large-grained CIGS film with (220/204) texture was formed at 400°C with the inclusion of a thin (80 nm) In2Se3 layer and liquid phase (excess copper selenide phase) formation, and the reaction mechanism is proposed. The device deposited at 2.0 Pa on an In2Se3 layer exhibited the optimal electrical properties. [Figure not available: see fulltext.

  18. Oxidation Kinetics of Chemically Vapor-Deposited Silicon Carbide in Wet Oxygen

    Science.gov (United States)

    Opila, Elizabeth J.

    1994-01-01

    The oxidation kinetics of chemically vapor-deposited SiC in dry oxygen and wet oxygen (P(sub H2O) = 0.1 atm) at temperatures between 1200 C and 1400 C were monitored using thermogravimetric analysis. It was found that in a clean environment, 10% water vapor enhanced the oxidation kinetics of SiC only very slightly compared to rates found in dry oxygen. Oxidation kinetics were examined in terms of the Deal and Grove model for oxidation of silicon. It was found that in an environment containing even small amounts of impurities, such as high-purity Al2O3 reaction tubes containing 200 ppm Na, water vapor enhanced the transport of these impurities to the oxidation sample. Oxidation rates increased under these conditions presumably because of the formation of less protective sodium alumino-silicate scales.

  19. Trends in the composition of wet deposition: effects of the atmospheric rehabilitation in East-Germany

    Science.gov (United States)

    Marquardt, Wolfgang; Brüggemann, Erika; Ihle, Peter

    1996-07-01

    The chemical components in precipitation largely depend on type and quantity of emissions on the course of the air masses at the sampling site. Beginning in 1982, the concentrations of major ions in precipitation at initially 3 sites are described in total as well as arrival sectors. For regions with specific geographical or emission features, 5 to 7 sectors for every sampling site are established, e.g., Scandinavia, or the centres of brown coal combustion in the former GDR. Particulary from the sectors of the former GDR, the precipitation was over-averaged contaminated anthropogenically in the years before the political change. Some components were significantly raised in comparison to other sectors. However, acidity remained on the level of the other sectors in the 80s. In the early 90s, anthropogenic emissions were systematically reduced partly by substitution of brown coal of inferior quality, better flue gas cleaning and partly by closing down industries. The effect of such steps on the wet deposition is being studied in a national German SANA research project (SANA: scientific program of rehabilitation of the atmosphere). In this project, the sampling sites were extended to 7 while maintaining the sampling procedure and the recording of relevant meteorological input-data. As a result, there now exists a homogeneous long-term data base allowing us to study the effects of emissions on wet deposition by the rehabilitation of the atmosphere in the former GDR. The paper focusses on changes in sulphate, nitrate, calcium, acidity, chloride and potassium concentrations in precipitation at the 3 so-called long-term sites. There are conspicuous decreases of some ions on one hand, but there is also an increase of nitrate and acidity, especially in recent years.

  20. Wet deposition at the base of Mt Everest: Seasonal evolution of the chemistry and isotopic composition

    Science.gov (United States)

    Balestrini, Raffaella; Delconte, Carlo A.; Sacchi, Elisa; Wilson, Alana M.; Williams, Mark W.; Cristofanelli, Paolo; Putero, Davide

    2016-12-01

    The chemistry of wet deposition was investigated during 2012-2014 at the Pyramid International Laboratory in the Upper Khumbu Valley, Nepal, at 5050 m a.s.l., within the Global Atmosphere Watch (GAW) programme. The main hydro-chemical species and stable isotopes of the water molecule were determined for monsoon rain (July-September) and snow samples (October-June). To evaluate the synoptic-scale variability of air masses reaching the measurement site, 5 day back-trajectories were computed for the sampling period. Ion concentrations in precipitation during the monsoon were low suggesting that they represent global regional background concentrations. The associations between ions suggested that the principal sources of chemical species were marine aerosols, rock and soil dust, and fossil fuel combustion. Most chemical species exhibited a pattern during the monsoon, with maxima at the beginning and at the end of the season, partially correlated with the precipitation amount. Snow samples exhibited significantly higher concentrations of chemical species, compared to the monsoon rainfall observations. Particularly during 2013, elevated concentrations of NO3-, SO42- and NH4+ were measured in the first winter snow event, and in May at the end of the pre-monsoon season. The analysis of large-scale circulation and wind regimes as well as atmospheric composition observations in the region indicates the transport of polluted air masses from the Himalayan foothills and Indian sub-continent up to the Himalaya region. During the summer monsoon onset period, the greater values of pollutants can be attributed to air-mass transport from the planetary boundary layer (PBL) of the Indo-Gangetic plains. Isotopic data confirm that during the monsoon period, precipitation occurred from water vapor that originated from the Indian Ocean and the Bay of Bengal; by contrast during the non-monsoon period, an isotopic signature of more continental origin appeared, indicating that the higher

  1. The interconnection of wet and dry deposition and the alteration of deposition budgets due to incorporation of new process understanding in regional models

    Science.gov (United States)

    Dennis, R. L.; Bash, J. O.; Foley, K. M.; Gilliam, R.; Pinder, R. W.

    2013-12-01

    Deposition is affected by the chemical and physical processes represented in the regional models as well as source strength. The overall production and loss budget (wet and dry deposition) is dynamically connected and adjusts internally to changes in process representation. In addition, the scrubbing of pollutants from the atmosphere by precipitation is one of several processes that remove pollutants, creating a coupling with the atmospheric aqueous and gas phase chemistry that can influence wet deposition rates in a nonlinear manner. We explore through model sensitivities with the regional Community Multiscale Air Quality (CMAQ) model the influence on wet and dry deposition, and the overall continental nitrogen budget, of changes in three process representations in the model: (1) incorporation of lightning generated NO, (2) improved representation of convective precipitation, and (3) replacement of the typical unidirectional dry deposition of NH3 with a state of the science representation of NH3 bi-directional air-surface exchange. Results of the sensitivity studies will be presented. (1) Incorporation of lightning generated NO significantly reduces a negative bias in summer wet nitrate deposition, but is sensitive to the choice of convective parameterization. (2) Use of a less active trigger of convective precipitation in the WRF meteorological model to reduce summertime precipitation over prediction bias reduces the generation of NO from lightning. It also reduces the wet deposition of nitrate and increases the dry deposition of oxidized nitrogen, as well as changing (reducing) the surface level exposure to ozone. Improvements in the convective precipitation processes also result in more non-precipitating clouds leading to an increase in SO4 production through the aqueous pathway resulting in improvements in summertime SO4 ambient aerosol estimates.(3) Incorporation of state of the science ammonia bi-directional air surface exchange affects both the dry

  2. Evaluating Inter-Annual Climate Variability of Nitrogen Wet Deposition in the United States Using Wavelet Analysis

    Science.gov (United States)

    Nergui, T.; Thomas, N.; Liu, M.; Lamb, B. K.; Adam, J. C.; Chung, S. H.

    2012-12-01

    Human activities, primarily agricultural practices and fossil fuel combustion, have caused a significant increase in nitrogen (N) emissions into the atmosphere over the last 150 years. The increase in emission subsequently leads to elevated ozone concentration, haze, increased acid rain and N deposition at local and regional scales. Many ecosystems in the US are naturally N limited. These regions are highly vulnerable to increased N deposition which can lead to irreversible changes in biodiversity richness and composition of the ecosystems. Through the impact on atmospheric chemistry and scavenging by precipitation, climate variability can play a major role on N deposition rates. The El Niño/Southern Oscillation (ENSO), Northern Annular Mode/Arctic Oscillation (NAM/AO), North Atlantic Oscillation (NAO), and the Pacific-North American Pattern (PNA) indices are the key climate indices that characterize the climate in the contiguous US at inter-annual timescale. Here, we identify dominant periodic components (signal) in the N wet deposition and the climate index timeseries and examine their correlations and coherences using wavelet analysis. Seasonal precipitation and nitrogen (ammonium and nitrate) wet deposition data from the National Atmospheric Deposition Program (NADP), National Trends Network (NTN) for 87 sites across the United States are used for the study. The sites were selected based on data continuity of 21 years or more and NADP criteria for valid precipitation and wet deposition data. Precipitation data from the Parameter-elevation Regressions on Independent Slopes Model (PRISM) are also used to replicate and validate the general features of climate variability effects in different regions of US. Initial analysis reveals nitrate wet deposition has a dominant 1-4 year periodicity while ammonium wet deposition has a shorter periodicity (about 0.5-2 year) during 1979 to 2011. Precipitation and total N wet deposition are most correlated in the Great Plains

  3. Long term precipitation chemistry and wet deposition in a remote dry savanna site in Africa (Niger

    Directory of Open Access Journals (Sweden)

    C. Galy-Lacaux

    2008-03-01

    VWM concentrations around the mean (1994–2005 presents fluctuations between ±5% and ±30% mainly attributed to the variations of sources strength associated with rainfall spatio-temporal distribution. From 1994 to 2005, the total mean wet deposition flux in the Sahelian region is 60.1 mmol.m−2.yr−1 and fluctuates around ±25%. Finally, Banizoumbou measurements, are compared to other long-term measurements of precipitation chemistry in the wet savanna of Lamto (Côte d'Ivoire and in the forested zone of Zoétélé (Cameroon. The total chemical loadings presents a strong negative gradient from the dry savanna to the forest (143.7, 100.2 to 86.6 μeq.l–1, associated with the gradient of terrigeneous compounds sources. The wet deposition fluxes present an opposite gradient, with 60.0 mmol.m−2.yr−1 in Banizoumbou, 108.6 mmol.m−2.yr–1 in Lamto and 162.9 mmol.m−2.yr−1 in Zoétélé, controlled by the rainfall gradient along the ecosystems transect.

  4. Effects of wet deposition on optical properties of the atmosphere over Bermuda and Barbados

    Science.gov (United States)

    Todd, Deborah L.; Keene, William C.; Moody, Jennie L.; Maring, Hal; Galloway, James N.

    2003-02-01

    Substantial spatial and temporal variabilities in chemical and physical properties of aerosols complicate attempts to model associated influences on global climate. Although wet deposition is the major mechanism by which most aerosols are removed from the atmosphere, direct effects of precipitation on radiative properties of the atmosphere are not well understood. To address this issue, attenuation coefficients for total insoluble constituents (ACt) and for nonvolatile (at 500°C) insoluble constituents (ACnv; primarily crustal dust) of precipitation at Bermuda and Barbados were measured at six wavelengths between 414 and 859 nm. Coefficients for volatile (at 500°C) insoluble constituents (ACv; primarily carbonaceous species) were calculated by difference. Between April and September, ACt at Bermuda was dominated by mineral constituents transported from North Africa, whereas carbonaceous species from North America were relatively low and exhibited no systematic seasonal variability. ACt and ACnv at Barbados were dominated by mineral dust, especially between April and September. Relative to ACv, ACnv decreased more rapidly with increasing wavelength. The wavelength dependencies of ACs for volatile and nonvolatile constituents at Bermuda were statistically indistinguishable from those at Barbados. The optical and chemical characteristics of precipitation were compared with scattering and absorption by ambient aerosols in associated air parcels to evaluate the influence of scavenging on the radiative properties of air. Although discernible relationships were evident, the small number of cases limited their applicability as reliable empirical predictors. However, these data do provide useful constraints for validating models of aerosol scavenging and wet removal on the optical properties of the troposphere.

  5. Radiocaesium activity in rape oil and in rape cake after a wet deposition event

    Energy Technology Data Exchange (ETDEWEB)

    Chaiko, Y.; Rappe-George, M.; Bengtsson, S. [Department of Soil and Environment (Sweden)

    2014-07-01

    After a release of radionuclides in agricultural areas there can be concerns on the levels of radionuclides in food products produced. The uptake of radionuclides via the above ground plant parts is a very important transport route into the food chain for humans as caesium is relatively mobile inside plants. In the production of rape oil the use of a processing factor (Pf) is used to estimate the activity concentration of radioactivity in the final oil product based on the activity concentration in rape seeds. The processing factor has been estimated to be 0.004 for caesium in rape oil by IAEA, and is based on a limited numbers of studies (1). In this project we analysed the activity concentration of radiocaesium ({sup 134}Cs) in rape oil and in rape cake from rape seeds contaminated after a wet deposition event with {sup 134}Cs. With the information of activity concentration of {sup 134}Cs in rape oil and in rape cake, we calculated the Pf-value and confirm or suggest new enhanced Pf-value. We analysed the activity concentration of {sup 134}Cs in rape oil and in rape cake from spring oilseed rape seeds (Brassica napus L.) that had been contaminated experimentally by wet deposited {sup 134}Cs in an earlier experiment by Bengtsson et al. (2013). The estimation of activity concentration of {sup 134}Cs in rape oil and in rape cake was achieved by performing extraction of the oil (and other extractable compounds) from the seeds based on the Randall extraction method (Randall, 1974) using petroleum ether as extraction chemical. The extracted oil and the rape cake samples were weighed and the activity concentration was measured with High-Purity Germanium (HPGe) detectors. Pf-values were calculated by dividing the measured activity concentration in rape oil after extraction by the activity concentration in oilseed rape seeds before extraction. Results from the present study will be presented at the international conference on radioecology and environmental radioactivity

  6. Dry and wet "deposition" studies of the degradation of cement mortars

    Directory of Open Access Journals (Sweden)

    Martínez-Ramírez, S.

    1998-06-01

    Full Text Available The reaction of portland cement mortars with SO2 gaseous pollutant and artificial 'acid rain' solution has been examined using laboratory exposure chambers, with realistic presentation rates of pollutants. The mortar were previously carbonated to produce superficial carbonation. Two mortars with different w/c ratio and hence specific surface were prepared and exposed into the chambers. For dry deposition of SO2 pollutant gas, the important roles of water and water plus oxidant in increasing chemical reaction are readily revealed. Further, accessible porosity also increases reaction through increased times of reaction of pollutant with the mortars. Interestingly, in the absence of deliberate surface wetting, the presence of oxidant, ozone, leads to a reduction in the already limited extent of reaction. Wet deposition studies using artificial 'acid rain' solution result in gypsum formation, which is more extensive for mortars of increased w/c ratios.

    Se han realizado ensayos de laboratorio de simulación de los procesos ambientales de "deposición" seca y húmeda sobre morteros de cemento portland, estudiándose las reacciones que se producen con el contaminante SO2 ("deposición" seca y la disolución de 'lluvia acida' ("deposición" húmeda. Los morteros de cemento se carbonataron para favorecer la carbonatación superficial de los mismos. Se prepararon morteros con dos relaciones a/c con el fin de estudiar la influencia que la variable superficie específica tenía en el proceso de deterioro de dichos materiales. En los estudios de deposición seca con SO2 como gas agresivo se ha visto la importancia que el agua y el agua junto a un oxidante tienen en la reacción del contaminante con los componentes del mortero. La superficie específica Juega un papel importante, ya que al aumentar, aumenta la reacción con el contaminante. La reacción en presencia de oxidante, (SO2+O3

  7. Sensitivity of the modelled deposition of Caesium-137 from the Fukushima Dai-ichi nuclear power plant to the wet deposition parameterisation in NAME.

    Science.gov (United States)

    Leadbetter, Susan J; Hort, Matthew C; Jones, Andrew R; Webster, Helen N; Draxler, Roland R

    2015-01-01

    This paper describes an investigation into the impact of different meteorological data sets and different wet scavenging coefficients on the model predictions of radionuclide deposits following the accident at the Fukushima Dai-ichi nuclear power plant in March 2011. Three separate operational meteorological data sets, the UK Met Office global meteorology, the ECMWF global meteorology and the Japan Meteorological Agency (JMA) mesoscale meteorology as well as radar rainfall analyses from JMA were all used as inputs to the UK Met Office's dispersion model NAME (the Numerical Atmospheric-dispersion Modelling Environment). The model predictions of Caesium-137 deposits based on these meteorological models all showed good agreement with observations of deposits made in eastern Japan with correlation coefficients ranging from 0.44 to 0.80. Unexpectedly the NAME run using radar rainfall data had a lower correlation coefficient (R = 0.66), when compared to observations, than the run using the JMA mesoscale model rainfall (R = 0.76) or the run using ECMWF met data (R = 0.80). Additionally the impact of modifying the wet scavenging coefficients used in the parameterisation of wet deposition was investigated. The results showed that modifying the scavenging parameters had a similar impact to modifying the driving meteorology on the rank calculated from comparing the modelled and observed deposition. Crown Copyright © 2014. Published by Elsevier Ltd. All rights reserved.

  8. Modeling wet deposition and concentration of inorganics over Northeast Asia with MRI-PM/c

    Directory of Open Access Journals (Sweden)

    M. Kajino

    2012-11-01

    Full Text Available We conducted a regional-scale simulation over Northeast Asia for the year 2006 using an aerosol chemical transport model, with time-varying lateral and upper boundary concentrations of gaseous species predicted by a global stratospheric and tropospheric chemistry-climate model. The present one-way nested global-through-regional-scale model is named the Meteorological Research Institute–Passive-tracers Model system for atmospheric Chemistry (MRI-PM/c. We evaluated the model's performance with respect to the major anthropogenic and natural inorganic components, SO42−, NH4+, NO3, Na+ and Ca2+ in the air, rain and snow measured at the Acid Deposition Monitoring Network in East Asia (EANET stations. Statistical analysis showed that approximately 40–50 % and 70–80 % of simulated concentration and wet deposition of SO42−, NH4+, NO3and Ca2+ are within factors of 2 and 5 of the observations, respectively. The prediction of the sea-salt originated component Na+ was not successful at near-coastal stations (where the distance from the coast ranged from 150 to 700 m, because the model grid resolution (Δx=60 km is too coarse to resolve it. The simulated Na+ in precipitation was significantly underestimated by up to a factor of 30.

  9. Long term precipitation chemistry and wet deposition in a remote dry savanna site in Africa (Niger

    Directory of Open Access Journals (Sweden)

    C. Galy-Lacaux

    2009-03-01

    , the total mean wet deposition flux in the Sahelian region is of 60.1 mmol.m−2.yr−1 ±25%. Finally, Banizoumbou measurements are compared to other long-term measurements of precipitation chemistry in the wet savanna of Lamto (Côte d'Ivoire and in the forested zone of Zoétélé (Cameroon. The total chemical loading presents a maximum in the dry savanna and a minimum in the forest (from 143.7, 100.2 to 86.6 μeq.l−1, associated with the gradient of terrigeneous sources. The wet deposition fluxes present an opposite trend, with 60.0 mmol.m−2.yr−1 in Banizoumbou, 108.6 mmol.m−2.yr−1 in Lamto and 162.9 mmol.m−2.yr−1 in Zoétélé, controlled by rainfall gradient along the ecosystems transect.

  10. Interception of wet deposited atmospheric pollutants by herbaceous vegetation: Data review and modelling

    Energy Technology Data Exchange (ETDEWEB)

    Gonze, M.-A., E-mail: marc-andre.gonze@irsn.fr; Sy, M.M.

    2016-09-15

    Better understanding and predicting interception of wet deposited pollutants by vegetation remains a key issue in risk assessment studies of atmospheric pollution. We develop different alternative models, following either empirical or semi-mechanistic descriptions, on the basis of an exhaustive dataset consisting of 440 observations obtained in controlled experiments, from 1970 to 2014, for a wide variety of herbaceous plants, radioactive substances and rainfall conditions. The predictive performances of the models and the uncertainty/variability of the parameters are evaluated under Hierarchical Bayesian modelling framework. It is demonstrated that the variability of the interception fraction is satisfactorily explained and quite accurately modelled by a process-based alternative in which absorption of ionic substances onto the foliage surfaces is determined by their electrical valence. Under this assumption, the 95% credible interval of the predicted interception fraction encompasses 81% of the observations, including situations where either plant biomass or rainfall intensity are unknown. This novel approach is a serious candidate to challenge existing empirical relationships in radiological or chemical risk assessment tools. - Highlights: • Literature data on the interception of atmospheric pollutants by herbs were reviewed • Predictive models were developed and evaluated in the Bayesian modelling framework • Sensitivity of interception to environmental conditions was satisfactorily explained • 81% of the observations were satisfactorily predicted by a semi-mechanistic model • This model challenges empirical relationships currently used in risk assessment tools.

  11. 3D Numerical Modelling of Transport, Deposition and Resuspension of Highway Deposited Sediments in Wet Detention Ponds

    DEFF Research Database (Denmark)

    Bentzen, Thomas Ruby

    2009-01-01

    The paper presents results from an experimental and numerical study of flows and transport of primarily particle bound pollutants in highway wet detention ponds. The study presented here is part of a general investigation on road runoff and pollution in respect to wet detention ponds. The objecti...

  12. Relationships between the El Niño-Southern Oscillation, precipitation, and nitrogen wet deposition rates in the contiguous United States

    Science.gov (United States)

    Nergui, Tsengel; Evans, R. David; Adam, Jennifer C.; Chung, Serena H.

    2016-11-01

    Human activities have significantly increased reactive nitrogen (N) in the environment, leading to adverse effects on various ecosystems. We used 1979-2012 seasonal inorganic N wet deposition data from the National Atmospheric Deposition Program to evaluate the relationship between the El Niño-Southern Oscillation (ENSO) and N wet deposition in the contiguous U.S. The correlations between precipitation and inorganic N wet deposition were the strongest and most spatially extensive during winter; up to 62% and 53% of the 2 to 6 year variations of precipitation and N wet deposition rates, respectively, in the Rocky Mountains, along the coast of the Gulf of Mexico and near the Great Lakes, can be explained by variation in the NINO3.4 climate index, which was used as a measure of ENSO activity. During El Niño winters, precipitation and N wet deposition rates were higher than normal in the southern U.S., while La Niña events brought higher precipitation and N wet deposition to the Rocky Mountains and Great Lakes regions. Wintertime N wet deposition correlations held through springtime in the Great Lakes and the northeast; however, correlations between NINO3.4 and precipitation were not significant at most sites, suggesting factors besides precipitation amount contributed to the 2 to 6 year variation of N wet deposition in these regions. As the frequency, strength, and types of ENSO change in the future, interannual variability of N wet deposition will be affected, indirectly affecting spatial distribution of dry N deposition and potentially changing the overall spatial patterns of N deposition.

  13. Characterization of Wet and Dry Deposition in the Downwind of Industrial Sources in a Dry Tropical Area

    Directory of Open Access Journals (Sweden)

    Raj K. Singh

    2001-01-01

    Full Text Available An atmospheric deposition study was conducted in the downwind of Shaktinagar Thermal Power Plant (STPP, Renusagar Thermal Power Plant (RTPP, and Anpara Thermal Power Plant (ATPP, at Singrauli region, Uttar Pradesh (UP, India to characterize dry and wet deposition in relation to different pollution loading. During the study period, dry and wet depositions and levels of gaseous pollutants (SO2 and NO2 were estimated across the sites. Dry deposition was collected on a monthly basis and wet deposition on an event basis. Depositions were analyzed for pH, nitrate (NO3�, ammonium (NH4+, and sulphate (SO42� contents. Dry deposition rate both collected as clearfall and throughfall varied between 0.15 to 2.28 and 0.33 to 3.48 g m�2 day�1, respectively, at control and maximally polluted sites. The pH of dry deposition varied from 5.81 to 6.89 during winter and 6.09 to 7.02 during summer across the sites. During the rainy season, the mean pH of clear wet deposition varied from 6.56 to 7.04 and throughfall varied from 6.81 to 7.22. The concentrations of NO2 and SO2 pollutants were highest during the winter season. Mean SO2 concentrations varied from 18 to 75 �g m�3 at control and differently polluted sites during the winter season. The variation in NO2 concentrations did not show a pattern similar to that of SO2. The highest NO2 concentration during the winter season was 50 �g m�3, observed near RTPP. NO2 concentration did not show much variation among different sites, suggesting that the sources of NO2 emission are evenly distributed along the sites. The concentrations of NH4+, NO3�, and SO42� ions in dry deposition were found to be higher in summer as compared to the winter season. In dry deposition (clearfall the concentrations of NH4+, NO3�, and SO42� varied from 0.13 to 1.0, 0.81 to 1.95, and 0.82 to 3.27 mg l�1, respectively, during winter. In wet deposition (clearfall, the above varied from 0.14 to 0.74, 0.81 to 1.82, and 0

  14. Control on wetting properties of spin-deposited silica films by surface silylation method

    Energy Technology Data Exchange (ETDEWEB)

    Rao, A. Venkateswara, E-mail: avrao2012@gmail.com [Air Glass Laboratory, Department of Physics, Shivaji University, Kolhapur 416 004, Maharashtra (India); Latthe, Sanjay S.; Dhere, Sunetra L.; Pawar, Swapnali S. [Air Glass Laboratory, Department of Physics, Shivaji University, Kolhapur 416 004, Maharashtra (India); Imai, Hiroaki [Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522 (Japan); Ganesan, V. [CSR, Indore Centre, University Campus, Khandwa Road, Indore 452 017, Madhyapradesh (India); Gupta, Satish C.; Wagh, Pratap B. [Applied Physics Division, Bhabha Atomic Research Centre (BARC), Trombay, Mumbai 400 085 (India)

    2010-01-15

    Control on the wettability of solid materials by liquid is a classical and key issue in surface engineering. Optically transparent water-repellent silica films have been spin-deposited on glass substrates at room temperature ({approx}27 deg. C). The wetting behavior of silica films was controlled by surface silylation method using dimethylchlorosilane (DMCS) as a silylating reagent. A coating sol was prepared by keeping the molar ratio of methyltrimethoxysilane (MTMS) precursor, methanol (MeOH) solvent, water (H{sub 2}O) constant at 1:8.8:2.64 respectively, with 4 M NH{sub 4}OH as a catalyst throughout the experiments and the amount of DMCS in hexane was varied from 0 to 12 vol.%. It was found that with an increase in vol.% of DMCS, the water contact angle values of the films increased from 78 deg. to 136 deg. At 12 vol.% of DMCS, the film shows static water contact angle as high as 136 deg. and water sliding angle as low as 18 deg. The hydrophobic silica films retained their water repellency up to a temperature 295 deg. C and above this temperature the films show superhydrophilic behavior. These results are compared with our earlier research work done on silylation of silica surface using hexamethyldisilazane (HMDZ) and trimethylchlorosilane (TMCS). The hydrophobic silica films were characterized by taking into consideration the Fourier transform infrared (FT-IR) spectroscopy, thermo gravimetric-differential thermal (TG-DT) analyses, scanning electron microscopy (SEM), atomic force microscopy (AFM), % of optical transmission, thermal and chemical aging tests, humidity tests, static and dynamic water contact angle measurements.

  15. Control on wetting properties of spin-deposited silica films by surface silylation method

    Science.gov (United States)

    Rao, A. Venkateswara; Latthe, Sanjay S.; Dhere, Sunetra L.; Pawar, Swapnali S.; Imai, Hiroaki; Ganesan, V.; Gupta, Satish C.; Wagh, Pratap B.

    2010-01-01

    Control on the wettability of solid materials by liquid is a classical and key issue in surface engineering. Optically transparent water-repellent silica films have been spin-deposited on glass substrates at room temperature (˜27 °C). The wetting behavior of silica films was controlled by surface silylation method using dimethylchlorosilane (DMCS) as a silylating reagent. A coating sol was prepared by keeping the molar ratio of methyltrimethoxysilane (MTMS) precursor, methanol (MeOH) solvent, water (H 2O) constant at 1:8.8:2.64 respectively, with 4 M NH 4OH as a catalyst throughout the experiments and the amount of DMCS in hexane was varied from 0 to 12 vol.%. It was found that with an increase in vol.% of DMCS, the water contact angle values of the films increased from 78° to 136°. At 12 vol.% of DMCS, the film shows static water contact angle as high as 136° and water sliding angle as low as 18°. The hydrophobic silica films retained their water repellency up to a temperature 295 °C and above this temperature the films show superhydrophilic behavior. These results are compared with our earlier research work done on silylation of silica surface using hexamethyldisilazane (HMDZ) and trimethylchlorosilane (TMCS). The hydrophobic silica films were characterized by taking into consideration the Fourier transform infrared (FT-IR) spectroscopy, thermo gravimetric-differential thermal (TG-DT) analyses, scanning electron microscopy (SEM), atomic force microscopy (AFM), % of optical transmission, thermal and chemical aging tests, humidity tests, static and dynamic water contact angle measurements.

  16. Monthly variations in nitrogen isotopes of ammonium and nitrate in wet deposition at Guangzhou, south China

    Science.gov (United States)

    Jia, Guodong; Chen, Fajin

    2010-06-01

    Monthly nitrogen isotopes of ammonium and nitrate in wet deposition in the city of Guangzhou, and the causes of their variability, are reported in this paper. Nitrate δ 15N showed nearly constant values around zero in the dry season (October to April), but oscillating values from negative to positive in the rainy season (May to September). By contrast, ammonium δ 15N displayed lower values during the rainy season than in the dry season. The rural area north of the city was considered as the prominent source of ammonium and nitrate in spring and early summer (May and June), as suggested by their concurrent negative isotopic trends and higher NH 4+/NO 3- ratios. From July to September, different dominating sources from the city, i.e., fossil fuel combustion for nitrate, and sewage and waste emission for ammonium, caused disparate δ 15N trends of the two species, showing positive nitrate δ 15N, but still negative ammonium δ 15N. During the cool dry season, the high values of ammonium δ 15N and concurrently low NH 4+/NO 3- ratios suggested the decrease in NH 3 volatilization and relatively important thermogenic origin of ammonium, but the intermediate nitrate δ 15N values around zero may be a result of a balanced emission of NO x from the city and the rural areas. The isotopic effects of chemical conversion of NO x to nitrate and washout of nitrate were ruled out as significant causes of nitrate δ 15N variability, but ammonium washout, during which 15N is assumed to be preferentially removed, may partly contribute to the ammonium δ 15N variability.

  17. Mobilization and distribution of lead originating from roof dust and wet deposition in a roof runoff system.

    Science.gov (United States)

    Yu, Jianghua; Yu, Haixia; Huang, Xiaogu

    2015-12-01

    In this research, the mobilization and distribution of lead originating in roof dust and wet deposition were investigated within a roof dust-rooftop-runoff system. The results indicated that lead from roof dust and wet deposition showed different transport dynamics in runoff system and that this process was significantly influenced by the rainfall intensity. Lead present in the roof dust could be easily washed off into the runoff, and nearly 60 % of the total lead content was present in particulate form. Most of the lead from the roof dust was transported during the late period of rainfall; however, the lead concentration was higher for several minutes at the rainfall beginning. Even though some of the lead from wet deposition, simulated with a standard isotope substance, was adsorbed onto adhered roof dust and/or retained on rooftop in runoff system, most of it (50-82 %) remained as dissolved lead in the runoff for rainfall events of varying intensity. Regarding the distribution of lead in the runoff system, the results indicated that it could be carried in the runoff in dissolved and particulate form, be adsorbed to adhered roof dust, or remain on the rooftop because of adsorption to the roof material. Lead from the different sources showed different distribution patterns that were also related to the rainfall intensity. Higher rainfall intensity resulted in a higher proportion of lead in the runoff and a lower proportion of lead remaining on the rooftop.

  18. The effect of dry and wet deposition of condensable vapors on secondary organic aerosols concentrations over the continental US

    Directory of Open Access Journals (Sweden)

    C. Knote

    2015-01-01

    Full Text Available The effect of dry and wet deposition of semi-volatile organic compounds (SVOCs in the gas phase on the concentrations of secondary organic aerosol (SOA is reassessed using recently derived water solubility information. The water solubility of SVOCs was implemented as a function of their volatility distribution within the WRF-Chem regional chemistry transport model, and simulations were carried out over the continental United States for the year 2010. Results show that including dry and wet removal of gas-phase SVOCs reduces annual average surface concentrations of anthropogenic and biogenic SOA by 48 and 63% respectively over the continental US. Dry deposition of gas-phase SVOCs is found to be more effective than wet deposition in reducing SOA concentrations (−40 vs. −8% for anthropogenics, and −52 vs. −11% for biogenics. Reductions for biogenic SOA are found to be higher due to the higher water solubility of biogenic SVOCs. The majority of the total mass of SVOC + SOA is actually deposited via the gas phase (61% for anthropogenics and 76% for biogenics. Results are sensitive to assumptions made in the dry deposition scheme, but gas-phase deposition of SVOCs remains crucial even under conservative estimates. Considering reactivity of gas-phase SVOCs in the dry deposition scheme was found to be negligible. Further sensitivity studies where we reduce the volatility of organic matter show that consideration of gas-phase SVOC removal still reduces average SOA concentrations by 31% on average. We consider this a lower bound for the effect of gas-phase SVOC removal on SOA concentrations. A saturation effect is observed for Henry's law constants above 108 M atm−1, suggesting an upper bound of reductions in surface level SOA concentrations by 60% through removal of gas-phase SVOCs. Other models that do not consider dry and wet removal of gas-phase SVOCs would hence overestimate SOA concentrations by roughly 50%. Assumptions about the water

  19. Comparative study of Hg xCd 1-xTe films grown on CdTe thin films previously deposited from two different techniques

    Science.gov (United States)

    Ali, A.; Abbas Shah, N.; Maqsood, A.

    2009-04-01

    High quality cadmium telluride (CdTe) thin films were grown on glass substrates with two different techniques, two evaporation source (TES) and closed space sublimation (CSS). Further to the above mercury telluride (HgTe) was then deposited by using single source on both CdTe thin films for obtaining Hg xCd 1-xTe samples. The crystalline structure of the Hg xCd 1-xTe sample grown from CSS-CdTe showed the preferential (1 1 1) orientation with smoother and larger grain size than those of TES-CdTe. The optical transmission for TES-CdTe sample was above 90% in the 1000-1500 nm range whereas it was significantly below 80% for CSS-CdTe sample. The optical transmission for TES-Hg xCd 1-xTe and CSS-Hg xCd 1-xTe was ˜60%. The resistivity at room temperature of TES-CdTe and CSS-CdTe was ˜3.33×10 9 Ω cm and ˜2.20×10 8 Ω cm, respectively, while the resistivity of TES-Hg xCd 1-xTe and CSS-Hg xCd 1-xTe samples was ˜1.73 Ω cm and ˜5.34×10 5 Ω cm, respectively. The comparative study of ternary compound prepared with the above techniques has been carried out for the first time.

  20. Silver nanoparticles deposited on amine-functionalized silica spheres and their amalgamation-based spectral and colorimetric detection of Hg(II) ions

    Energy Technology Data Exchange (ETDEWEB)

    Rameshkumar, Perumal; Manivannan, Shanmugam; Ramaraj, Ramasamy, E-mail: ramarajr@yahoo.com [Madurai Kamaraj University, Centre for Photoelectrochemistry, School of Chemistry (India)

    2013-05-15

    A facile synthetic method to decorate amine-functionalized silica spheres (SiO{sub 2}) by silver nanoparticles (Ag NPs) is reported. The transmission electron microscopic (TEM) images showed that spherical Ag NPs with an average particle size of 14 nm were deposited on 250 nm-sized SiO{sub 2} spheres (SiO{sub 2}/Ag NPs). The spectral and colorimetric detection of Hg(II) ions were carried out using the synthesized SiO{sub 2}/Ag NPs with an experimental detection limit of 5 {mu}M. It was found that the addition of Hg(II) ions (150 {mu}M) into the solution of SiO{sub 2}/Ag NPs completely quenched the SPR band of the Ag NPs due to the formation of anisotropic Ag amalgam crystals (AgHg). The selective detection of Hg(II) ions by SiO{sub 2}/Ag NPs in the presence of other environmentally relevant metal ions was also demonstrated using spectral and colorimetric methods.Graphical abstractAmine-functionalized silica spheres are decorated by in situ formation of silver nanoparticles and their spectral and colorimetric detection of Hg(II) ions is reported.

  1. Attributes for NHDPlus Catchments (Version 1.1) for the Conterminous United States: Average Atmospheric (Wet) Deposition of Inorganic Nitrogen, 2002

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set represents the average atmospheric (wet) deposition, in kilograms per square kilometer, of inorganic nitrogen for the year 2002 compiled for every...

  2. Attributes for MRB_E2RF1 Catchments by Major River Basins in the Conterminous United States: Average Atmospheric (Wet) Deposition of Inorganic Nitrogen, 2002

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This tabular data set represents the average atmospheric (wet) deposition, in kilograms per square kilometer, of inorganic nitrogen for the year 2002 compiled for...

  3. Interception and retention of wet-deposited radiocaesium and radiostrontium on a ley mixture of grass and clover.

    Science.gov (United States)

    Bengtsson, Stefan B; Gärdenäs, Annemieke I; Eriksson, Jan; Vinichuk, Mykhailo; Rosén, Klas

    2014-11-01

    The aims of this study were to assess the potential radioactive contamination of fodder in the case of accidental radionuclide fallout, and to analyse the relationship between interception and retention of radionuclides as a function of biomass and Leaf Area Index (LAI). The interception and the retention of wet deposited (134)Cs and (85)Sr in ley (a mixture of grass and clover) were measured after artificial wet deposition in a field trial in Uppsala (eastern central Sweden). The field trial had a randomised block design with three replicates. (134)Cs and (85)Sr were deposited at six different growth stages during two growing seasons (2010 and 2011) using a rainfall simulator. The biomass was sampled in the center of each parcel 2 to 3h after deposition and at later growth stages (1 to 5) during the growing season. The above ground biomass and LAI were measured as well. The interception of radionuclides by the ley was largest at the late growth stages; the spike and tassel/flowering (code 5:6) in the 1(st) year, and at flowering/initial flowering (code 6:5) in the 2(nd) year. There was a correlation between radionuclide interception and above ground plant biomass, as well as with LAI, for both radionuclides in both years. The highest activity concentrations of both radionuclides were measured after deposition at the late growth stages and were found to be higher in the 2(nd) year. The weathering half-lives were shorter at the earlier growth stages than at the later growth stages for both radionuclides. For the magnitude of deposition chosen in our experiment, it can be concluded that the above ground biomass is a good predictor and the LAI a more uncertain predictor of the interception of radiocaesium and radiostrontium by ley grass and clover.

  4. Size distribution of airborne particle-bound polybrominated diphenyl ethers and its implications for dry and wet deposition.

    Science.gov (United States)

    Luo, Pei; Ni, Hong-Gang; Bao, Lian-Jun; Li, Shao-Meng; Zeng, Eddy Y

    2014-12-01

    Size distribution of particles in part dictates the environmental behavior of particle-bound organic pollutants in the atmosphere. The present study was conducted to examine the potential mechanisms responsible for the distribution of organic pollutants in size fractionated particles and their environmental implications, using an e-waste recycling zone in South China as a case study. Size-fractionated atmospheric particles were collected at the heights of 1.5, 5, and 20 m near two residential apartments and analyzed for polybrominated diphenyl ethers (PBDEs). The concentrations of particle-bound ΣPBDE (sum of 18 PBDE congeners) were significantly greater at 5 and 20 m than those at 1.5 m. The size-fractionated distributions of airborne ΣPBDE displayed trimodal peaks in 0.10–0.18, 1.8–3.2, and 10–18 μm at 1.5 m but only an unimodal peak in 1.0–1.8 μm at 20 m height. Emission sources, resuspension of dust and soil, and volatility of PBDEs were important factors influencing the size distribution of particle-bound PBDEs. The dry deposition fluxes of particle-bound PBDE estimated from the measured data in the present study were approximately twice the estimated wet deposition fluxes, with a total deposition flux of 3000 ng m(–2) d(–1). The relative contributions of particles to dry and wet deposition fluxes were also size-dependent, e.g., coarse (aerodynamic diameters (Dp) > 1.8 μm) and fine (Dp deposition fluxes of PBDEs, respectively.

  5. Silver nanoparticles deposited on amine-functionalized silica spheres and their amalgamation-based spectral and colorimetric detection of Hg(II) ions

    Science.gov (United States)

    Rameshkumar, Perumal; Manivannan, Shanmugam; Ramaraj, Ramasamy

    2013-05-01

    A facile synthetic method to decorate amine-functionalized silica spheres (SiO2) by silver nanoparticles (Ag NPs) is reported. The transmission electron microscopic (TEM) images showed that spherical Ag NPs with an average particle size of 14 nm were deposited on 250 nm-sized SiO2 spheres (SiO2/Ag NPs). The spectral and colorimetric detection of Hg(II) ions were carried out using the synthesized SiO2/Ag NPs with an experimental detection limit of 5 μM. It was found that the addition of Hg(II) ions (150 μM) into the solution of SiO2/Ag NPs completely quenched the SPR band of the Ag NPs due to the formation of anisotropic Ag amalgam crystals (AgHg). The selective detection of Hg(II) ions by SiO2/Ag NPs in the presence of other environmentally relevant metal ions was also demonstrated using spectral and colorimetric methods.

  6. Short-term seasonal variability in 7Be wet deposition in a semiarid ecosystem of central Argentina.

    Science.gov (United States)

    Juri Ayub, J; Di Gregorio, D E; Velasco, H; Huck, H; Rizzotto, M; Lohaiza, F

    2009-11-01

    The (7)Be wet deposition has been intensively investigated in a semiarid region at San Luis Province, Argentina. From November 2006 to May 2008, the (7)Be content in rainwater was determined in 58 individual rain events, randomly comprising more than 50% of all individual precipitations at the sampling period. (7)Be activity concentration in rainwater ranged from 0.7+/-0.3 Bq l(-1) to 3.2+/-0.7 Bq l(-1), with a mean value of 1.7 Bq l(-1) (sd=0.53 Bq l(-1)). No relationship was found between (7)Be content in rainwater and (a) rainfall amount, (b) precipitation intensity and (c) elapsed time between events. (7)Be ground deposition was found to be well correlated with rainfall amount (R=0.92). For the precipitation events considered, the (7)Be depositional fluxes ranged from 1.1 to 120 Bq m(-2), with a mean value of 32.7 Bq m(-2) (sd=29.9 Bq m(-2)). The annual depositional flux was estimated at 1140+/-120 Bq m(-2)y(-1). Assuming the same monthly deposition pattern and that the (7)Be content in soil decreases only through radioactive decay, the seasonal variation of (7)Be areal activity density in soil was estimated. Results of this investigation may contribute to a valuable characterization of (7)Be input in the explored semiarid ecosystem and its potential use as tracer of environmental processes.

  7. Characterisation of nutrients wet deposition under influence of Saharan dust at Puerto-Rico in Caribbean Sea

    Science.gov (United States)

    Desboeufs, Karine; Formenti, Paola; Triquet, Sylvain; Laurent, Benoit; Denjean, Cyrielle; Gutteriez-Moreno, Ian E.; Mayol-Bracero, Olga L.

    2015-04-01

    Large quantities of African dust are carried across the North Atlantic toward the Caribbean every summer by Trade Winds. Atmospheric deposition of dust aerosols, and in particular wet deposition, is widely acknowledged to be the major delivery pathway for nutrients to ocean ecosystems, as iron, phosphorus and various nitrogen species. The deposition of this dustis so known to have an important impact on biogeochemical processes in the Tropical and Western Atlantic Ocean and Caribbean including Puerto-Rico. However, very few data exists on the chemical composition in nutrients in dusty rain in this region. In the framework of the Dust-ATTAcK project, rainwater was collected at the natural reserve of Cape San Juan (CSJ) (18.38°N, 65.62°W) in Puerto-Ricobetween 20 June 2012 and 12 July 2012 during thedusty period. A total of 7 rainwater events were sampled during various dust plumes. Complementary chemical analyses on aerosols in suspension was also determined during the campaign. The results on dust composition showed that no mixing with anthropogenic material was observed, confirming dust aerosols were the major particles incorporated in rain samples. The partitioning between soluble and particulate nutrients in rain samples showed that phosphorous solubility ranged from 30 and 80%. The average Fe solubility was around 0.5%, in agreement with Fe solubility observed in rains collected in Niger during African monsoon. That means that the high solubility measurements previously observed in Caribbean was probably due to an anthropogenic influence. Atmospheric wet deposition fluxes of soluble and total nutrients (N, P, Si, Fe, Co, Cu, Mn, Ni, Zn) to Caribbean Sea were determined. Atmospheric P and N inputs were strongly depleted relative to the stoichiometry of phytoplankton Fe, N, P and Si requirements.The nitrogen speciation was also determined and showed the predominance of ammonium form. 3-D modeling was used to estimate the spatial extend of these fluxes over the

  8. The atmospheric pollution in the area of the Goczałkowice Reservoir changes based on wet and dry deposition

    Directory of Open Access Journals (Sweden)

    Mieczysław LEŚNIOK

    2014-11-01

    Full Text Available The Goczałkowice Reservoir was formed as a result of the accumulation of waters from the Vistula River caused by the construction of the earth dam of 2980 m in length between the town of Goczałkowice-Zdrój and Zabrzeg. It is located in Subcaprathia, near the Silesian Beskids mountain range (Outer Western Carpathians. Discussed reservoir was investigated in several environmental aspects. One of those researched elements was wet and dry pollution deposition in Integrated System Supporting Management and Protection of Water Reservoir (ZiZOZap.The research on wet and dry pollution deposition was carried out at two measurement points situated on the opposite sides of the Goczałkowice Reservoir. From the east side it was a station in Goczałkowice and from the west side a station in Frelichów (fig. 1.  The location of points allowed to assess influence of air masses from different directions and define sources of the pollutants.

  9. Liu et al. suspect that Zhu et al. (2015) may have underestimated dissolved organic nitrogen (N) but overestimated total particulate N in wet deposition in China.

    Science.gov (United States)

    Liu, Xuejun; Xu, Wen; Pan, Yuepeng; Du, Enzai

    2015-07-01

    In a recent publication in the journal Science of the Total Environment, Zhu et al. (2015) reported the composition, spatial patterns, and factors influencing atmospheric wet nitrogen (N) deposition based on one year's data from 41-monitoring sites in China. We suspect their results may largely underestimate dissolved organic N (DON) but overestimate total particulate N (TPN) in wet deposition due to the uncertainty resulting from the sampling, storage and analysis methods in their study. Our suspicions are based mainly on our experience from earlier measurements and the literature. We therefore suggest that enhanced data quality control on atmospheric N deposition measurements should be taken into account in future studies.

  10. Base surge deposits, eruption history, and depositional processes of a wet phreatomagmatic volcano in Central Anatolia (Cora Maar)

    Science.gov (United States)

    Gençalioğlu-Kuşcu, Gonca; Atilla, Cüneyt; Cas, Ray A. F.; Kuşcu, İlkay

    2007-01-01

    Cora Maar is a Quaternary volcano located to the 20 km northwest of Mount Erciyes, the largest of the 19 polygenetic volcanic complexes of the Cappadocian Volcanic Province in central Anatolia. Cora Maar is a typical example of a maar-diatreme volcano with a nearly circular crater with a mean diameter of c.1.2 km, and a well-bedded base surge-dominated maar rim tephra sequence up to 40 m in thickness. Having a diameter/depth ratio ( D/ d) of 12, Cora is a relatively "mature" maar compared to recent maar craters in the world. Cora crater is excavated within the andesitic lava flows of Quaternary age. The tephra sequence is not indurated, and consists of juvenile clasts up to 70 cm, non-juvenile clasts up to 130 cm, accretionary lapilli up to 1.2 cm in diameter, and ash to lapilli-sized tephra. Base surge layers display well-developed antidune structures indicating the direction of the transport. Both progressive and regressive dune structures are present within the tephra sequence. Wavelength values increase with increasing wave height, and with large wavelength and height values. Cora tephra display similarities to Taal and Laacher See base surge deposits. Impact sags and small channel structures are also common. Lateral and vertical facies changes are observed for the dune bedded and planar bedsets. According to granulometric analyses, Cora Maar tephra samples display a bimodal distribution with a wide range of Md φ values, characteristic for the surge deposits. Very poorly sorted, bimodal ash deposits generally vary from coarse tail to fine tail grading depending on the grain size distribution while very poorly sorted lapilli and block-rich deposits display a positive skewness due to fine tail grading.

  11. Inorganic nitrogen wet deposition: Evidence from the North-South Transect of Eastern China.

    Science.gov (United States)

    Zhan, X; Yu, G; He, N; Jia, B; Zhou, M; Wang, C; Zhang, J; Zhao, G; Wang, S; Liu, Y; Yan, J

    2015-09-01

    We examined the spatio-temporal variation of dissolved inorganic nitrogen (DIN) deposition in eight typical forest ecosystems of Eastern China for three consecutive years. DIN deposition exhibited an increasing gradient from north to south, with N-NH4(+) as the predominant contributor. DIN deposition in precipitation changed after interaction with the forest canopy, and serious ecological perturbations are expected in this region. DIN deposition presented seasonal fluctuations, which might be ascribed to agricultural activity, fossil-fuel combustion and environmental factors (i.e., wind direction, soil temperature). Notably, N fertilizer use (FN), energy consumption (E), and precipitation (P) jointly explained 84.3% of the spatial variation in DIN deposition, of which FN (27.2%) was the most important, followed by E (24.8%), and finally P (9.3%). The findings demonstrate that DIN deposition is regulated by precipitation mainly via anthropogenic N emissions, and this analysis provides decision-makers a novel view for N pollution abatement.

  12. The influence of regional circulation patterns on wet and dry mineral dust and sea salt deposition over Greenland

    Energy Technology Data Exchange (ETDEWEB)

    Hutterli, M.A. [University of Bern, Physics Institute, Bern (Switzerland); British Antarctic Survey, Physical Sciences Division, Cambridge (United Kingdom); Crueger, T. [Max-Planck-Institute for Meteorology, Hamburg (Germany); Fischer, H. [Alfred-Wegener-Institute for Polar and Marine Research, Bremerhaven (Germany); Andersen, K.K.; Siggaard-Andersen, M.L. [University of Copenhagen, Niels Bohr Institute, Copenhagen (Denmark); Raible, C.C.; Stocker, T.F. [University of Bern, Physics Institute, Bern (Switzerland); McConnell, J.R. [Desert Research Institute, Reno, NV (United States); Bales, R.C.; Burkhart, J.F. [University of California, Merced, Atwater, CA (United States)

    2007-05-15

    Annually resolved ice core records from different regions over the Greenland ice sheet (GrIS) are used to investigate the spatial and temporal variability of calcium (Ca{sup 2+}, mainly from mineral dust) and sodium (Na{sup +}, mainly from sea salt) deposition. Cores of high common inter-annual variability are grouped with an EOF analysis, resulting in regionally representative Ca{sup 2+} and Na{sup +} records for northeastern and central Greenland. Utilizing a regression and validation method with ERA-40 reanalysis data, these common records are associated with distinct regional atmospheric circulation patterns over the North American Arctic, Greenland, and Central to Northern Europe. These patterns are interpreted in terms of transport and deposition of the impurities. In the northeastern part of the GrIS sea salt records reflect the intrusion of marine air masses from southeasterly flow. A large fraction of the Ca{sup 2+} variability in this region is connected to a circulation pattern suggesting transport from the west and dry deposition. This pattern is consistent with the current understanding of a predominantly Asian source of the dust deposited over the GrIS. However, our results also indicate that a significant fraction of the inter-annual dust variability in NE and Central Greenland is determined by the frequency and intensity of wet deposition during the season of high atmospheric dust loading, rather than representing the variability of the Asian dust source and/or long-range transport to Greenland. The variances in the regional proxy records explained by the streamfunction patterns are high enough to permit reconstructions of the corresponding regional deposition regimes and the associated circulation patterns. (orig.)

  13. Short-term seasonal variability in {sup 7}Be wet deposition in a semiarid ecosystem of central Argentina

    Energy Technology Data Exchange (ETDEWEB)

    Juri Ayub, J. [Grupo de Estudios Ambientales, Instituto de Matematica Aplicada San Luis, Universidad Nacional de San Luis - CONICET, Ejercito de los Andes 950, D5700HHW San Luis (Argentina); Di Gregorio, D.E. [Departamento de Fisica, Comision Nacional de Energia Atomica, Av. Gral. Paz 1499, 1650 San Martin, Provincia de Buenos Aires (Argentina); Escuela de Ciencia y Tecnologia, Universidad Nacional de San Martin, Martin de Irigoyen 3100, 1650 San Martin, Provincia de Buenos Aires (Argentina); Velasco, H. [Grupo de Estudios Ambientales, Instituto de Matematica Aplicada San Luis, Universidad Nacional de San Luis - CONICET, Ejercito de los Andes 950, D5700HHW San Luis (Argentina)], E-mail: hvelasco@unsl.edu.ar; Huck, H. [Departamento de Fisica, Comision Nacional de Energia Atomica, Av. Gral. Paz 1499, 1650 San Martin, Provincia de Buenos Aires (Argentina); Escuela de Ciencia y Tecnologia, Universidad Nacional de San Martin, Martin de Irigoyen 3100, 1650 San Martin, Provincia de Buenos Aires (Argentina); Rizzotto, M.; Lohaiza, F. [Grupo de Estudios Ambientales, Instituto de Matematica Aplicada San Luis, Universidad Nacional de San Luis - CONICET, Ejercito de los Andes 950, D5700HHW San Luis (Argentina)

    2009-11-15

    The {sup 7}Be wet deposition has been intensively investigated in a semiarid region at San Luis Province, Argentina. From November 2006 to May 2008, the {sup 7}Be content in rainwater was determined in 58 individual rain events, randomly comprising more than 50% of all individual precipitations at the sampling period. {sup 7}Be activity concentration in rainwater ranged from 0.7 {+-} 0.3 Bq l{sup -1} to 3.2 {+-} 0.7 Bq l{sup -1}, with a mean value of 1.7 Bq l{sup -1} (sd = 0.53 Bq l{sup -1}). No relationship was found between {sup 7}Be content in rainwater and (a) rainfall amount, (b) precipitation intensity and (c) elapsed time between events. {sup 7}Be ground deposition was found to be well correlated with rainfall amount (R = 0.92). For the precipitation events considered, the {sup 7}Be depositional fluxes ranged from 1.1 to 120 Bq m{sup -2}, with a mean value of 32.7 Bq m{sup -2} (sd = 29.9 Bq m{sup -2}). The annual depositional flux was estimated at 1140 {+-} 120 Bq m{sup -2} y{sup -1}. Assuming the same monthly deposition pattern and that the {sup 7}Be content in soil decreases only through radioactive decay, the seasonal variation of {sup 7}Be areal activity density in soil was estimated. Results of this investigation may contribute to a valuable characterization of {sup 7}Be input in the explored semiarid ecosystem and its potential use as tracer of environmental processes.

  14. Correlation of film density and wet etch rate in hydrofluoric acid of plasma enhanced atomic layer deposited silicon nitride

    Science.gov (United States)

    Provine, J.; Schindler, Peter; Kim, Yongmin; Walch, Steve P.; Kim, Hyo Jin; Kim, Ki-Hyun; Prinz, Fritz B.

    2016-06-01

    The continued scaling in transistors and memory elements has necessitated the development of atomic layer deposition (ALD) of silicon nitride (SiNx), particularly for use a low k dielectric spacer. One of the key material properties needed for SiNx films is a low wet etch rate (WER) in hydrofluoric (HF) acid. In this work, we report on the evaluation of multiple precursors for plasma enhanced atomic layer deposition (PEALD) of SiNx and evaluate the film's WER in 100:1 dilutions of HF in H2O. The remote plasma capability available in PEALD, enabled controlling the density of the SiNx film. Namely, prolonged plasma exposure made films denser which corresponded to lower WER in a systematic fashion. We determined that there is a strong correlation between WER and the density of the film that extends across multiple precursors, PEALD reactors, and a variety of process conditions. Limiting all steps in the deposition to a maximum temperature of 350 °C, it was shown to be possible to achieve a WER in PEALD SiNx of 6.1 Å/min, which is similar to WER of SiNx from LPCVD reactions at 850 °C.

  15. Correlation of film density and wet etch rate in hydrofluoric acid of plasma enhanced atomic layer deposited silicon nitride

    Energy Technology Data Exchange (ETDEWEB)

    Provine, J., E-mail: jprovine@stanford.edu; Schindler, Peter; Kim, Yongmin; Walch, Steve P.; Kim, Hyo Jin [Department of Mechanical Engineering, Stanford University, Stanford, California 94305 (United States); Kim, Ki-Hyun [Manufacturing Technology Center, Samsung Electronics, Suwon, Gyeonggi-Do (Korea, Republic of); Prinz, Fritz B. [Department of Mechanical Engineering, Stanford University, Stanford, California 94305 (United States); Department of Materials Science and Engineering, Stanford University, Stanford, California 94305 (United States)

    2016-06-15

    The continued scaling in transistors and memory elements has necessitated the development of atomic layer deposition (ALD) of silicon nitride (SiN{sub x}), particularly for use a low k dielectric spacer. One of the key material properties needed for SiN{sub x} films is a low wet etch rate (WER) in hydrofluoric (HF) acid. In this work, we report on the evaluation of multiple precursors for plasma enhanced atomic layer deposition (PEALD) of SiN{sub x} and evaluate the film’s WER in 100:1 dilutions of HF in H{sub 2}O. The remote plasma capability available in PEALD, enabled controlling the density of the SiN{sub x} film. Namely, prolonged plasma exposure made films denser which corresponded to lower WER in a systematic fashion. We determined that there is a strong correlation between WER and the density of the film that extends across multiple precursors, PEALD reactors, and a variety of process conditions. Limiting all steps in the deposition to a maximum temperature of 350 °C, it was shown to be possible to achieve a WER in PEALD SiN{sub x} of 6.1 Å/min, which is similar to WER of SiN{sub x} from LPCVD reactions at 850 °C.

  16. Correlation of film density and wet etch rate in hydrofluoric acid of plasma enhanced atomic layer deposited silicon nitride

    Directory of Open Access Journals (Sweden)

    J. Provine

    2016-06-01

    Full Text Available The continued scaling in transistors and memory elements has necessitated the development of atomic layer deposition (ALD of silicon nitride (SiNx, particularly for use a low k dielectric spacer. One of the key material properties needed for SiNx films is a low wet etch rate (WER in hydrofluoric (HF acid. In this work, we report on the evaluation of multiple precursors for plasma enhanced atomic layer deposition (PEALD of SiNx and evaluate the film’s WER in 100:1 dilutions of HF in H2O. The remote plasma capability available in PEALD, enabled controlling the density of the SiNx film. Namely, prolonged plasma exposure made films denser which corresponded to lower WER in a systematic fashion. We determined that there is a strong correlation between WER and the density of the film that extends across multiple precursors, PEALD reactors, and a variety of process conditions. Limiting all steps in the deposition to a maximum temperature of 350 °C, it was shown to be possible to achieve a WER in PEALD SiNx of 6.1 Å/min, which is similar to WER of SiNx from LPCVD reactions at 850 °C.

  17. Comparative study of CuO-CeO{sub 2} catalysts prepared by wet impregnation and deposition-precipitation

    Energy Technology Data Exchange (ETDEWEB)

    Gurbani, A.; Ayastuy, J.L.; Gonzalez-Marcos, M.P.; Gutierrez-Ortiz, M.A. [Departamento de Ingenieria Quimica, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco, Bilbao 48080 (Spain); Unidad Asociada ' ' Tecnologias Quimicas para la Sostenibilidad Ambiental' ' , CSIC-UPV/EHU (Spain); Herrero, J.E.; Guil, J.M. [Instituto de Quimica Fisica ' ' Rocasolano' ' - CSIC, Madrid 28006 (Spain); Unidad Asociada ' ' Tecnologias Quimicas para la Sostenibilidad Ambiental' ' , CSIC-UPV/EHU (Spain)

    2009-01-15

    Two different preparation methods are used to synthesize wt. 7% CuO-CeO{sub 2} catalysts: a conventional wet impregnation method, and a deposition-precipitation (DP) method using Na{sub 2}CO{sub 3} as precipitating agent. Both samples are characterized by a series of techniques. CuO-CeO{sub 2} (Cu-Ce) prepared by DP shows a lower capacity to release the lattice oxygen to form CO{sub 2}. From CO-TPR results, it is demonstrated that this catalyst is not able to reduce copper clusters at low temperatures. Also, CO-TPD shows no CO{sub 2} formation. The activity results confirm the worse performance of Cu-Ce prepared by DP especially when oxygen is not in excess (PROX reaction with stoichometric oxygen). A copper particle size which is too small could create a stronger metal-support interaction, with lower Cu-Ce interface to react. (author)

  18. Nitrogen chemistry in surface waters and wet deposition at high altitude in the Sagarmatha (Mt Everest) National Park.

    Science.gov (United States)

    Balestrini, R.; Polesello, S.; Rusconi, M.

    2012-04-01

    The knowledge of the nitrogen cycle is mainly based on studies conducted in relatively human-altered zones located in the north-western hemisphere. Therefore it is of great interest to identify the limits of natural variations of nitrogen in ecosystems that have not experienced the nitrogen pollution, and have undergone minor alterations from human activities. Among the alpine environments of the world, the region of Mount Everest, is a unique ecosystem with a degree of biodiversity among the highest existing, but characterized by a recognized fragility and low resilience. The extreme climate, the slow growing seasons and the thin soils make this ecosystem very sensitive to any environmental change. A yearly sampling campaign was conducted in the Sagarmatha National Park (Nepal) during the monsoon season in 2008 to collect surface water samples at high elevation from 4300 to 5500 m asl. In addition during 2007 and 2008 the sampling of wet deposition was carried on at 5050 m asl at the Nepal Climate Observatory - Pyramid ABC site. The nitrate concentration in the running waters fell in the lower range of the values reported for comparable environments in Europe. As well, the wet deposition load of nitrogen was remarkable lower than those observed in high elevation areas in Europe and North America. A comparison among running waters, precipitations and small lakes, located in the same area, revealed significant higher nitrate concentrations in running waters compared to the other two matrixes. Conversely, ammonia level resulted higher in the rain compared to surface waters. The spatial and temporal variation of the chemical species in running waters were analyzed taking in account the use of soil in the basins and the hydrological regime.

  19. Wetting behaviour of carbon nitride nanostructures grown by plasma enhanced chemical vapour deposition technique

    Science.gov (United States)

    Ahmad Kamal, Shafarina Azlinda; Ritikos, Richard; Abdul Rahman, Saadah

    2015-02-01

    Tuning the wettability of various coating materials by simply controlling the deposition parameters is essential for various specific applications. In this work, carbon nitride (CNx) films were deposited on silicon (1 1 1) substrates using radio-frequency plasma enhanced chemical vapour deposition employing parallel plate electrode configuration. Effects of varying the electrode distance (DE) on the films' structure and bonding properties were investigated using Field emission scanning electron microscopy, Atomic force microscopy, Fourier transform infrared and X-ray photoemission spectroscopy. The wettability of the films was analyzed using water contact angle measurements. At high DE, the CNx films' surface was smooth and uniform. This changed into fibrous nanostructures when DE was decreased. Surface roughness of the films increased with this morphological transformation. Nitrogen incorporation increased with decrease in DE which manifested the increase in both relative intensities of Cdbnd N to Cdbnd C and Nsbnd H to Osbnd H bonds. sp2-C to sp3-C ratio increased as DE decreased due to greater deformation of sp2 bonded carbon at lower DE. The films' characteristics changed from hydrophilic to super-hydrophobic with the decrease in DE. Roughness ratio, surface porosity and surface energy calculated from contact angle measurements were strongly dependent on the morphology, surface roughness and bonding properties of the films.

  20. Modeling and mapping of atmospheric mercury deposition in adirondack park, new york.

    Directory of Open Access Journals (Sweden)

    Xue Yu

    Full Text Available The Adirondacks of New York State, USA is a region that is sensitive to atmospheric mercury (Hg deposition. In this study, we estimated atmospheric Hg deposition to the Adirondacks using a new scheme that combined numerical modeling and limited experimental data. The majority of the land cover in the Adirondacks is forested with 47% of the total area deciduous, 20% coniferous and 10% mixed. We used litterfall plus throughfall deposition as the total atmospheric Hg deposition to coniferous and deciduous forests during the leaf-on period, and wet Hg deposition plus modeled atmospheric dry Hg deposition as the total Hg deposition to the deciduous forest during the leaf-off period and for the non-forested areas year-around. To estimate atmospheric dry Hg deposition we used the Big Leaf model. The average atmospheric Hg deposition to the Adirondacks was estimated as 17.4 [Formula: see text]g m[Formula: see text] yr[Formula: see text] with a range of -3.7-46.0 [Formula: see text]g m[Formula: see text] yr[Formula: see text]. Atmospheric Hg dry deposition (370 kg yr[Formula: see text] was found to be more important than wet deposition (210 kg yr[Formula: see text] to the entire Adirondacks (2.4 million ha. The spatial pattern showed a large variation in atmospheric Hg deposition with scattered areas in the eastern Adirondacks having total Hg deposition greater than 30 μg m(-2 yr(-1, while the southwestern and the northern areas received Hg deposition ranging from 25-30 μg m(-2 yr(-1.

  1. Total atmospheric mercury deposition in forested areas in South Korea

    Science.gov (United States)

    Han, Jin-Su; Seo, Yong-Seok; Kim, Moon-Kyung; Holsen, Thomas M.; Yi, Seung-Muk

    2016-06-01

    In this study, mercury (Hg) was sampled weekly in dry and wet deposition and throughfall and monthly in litterfall, and as it was volatilized from soil from August 2008 to February 2010 to identify the factors influencing the amount of atmospheric Hg deposited to forested areas in a temperate deciduous forest in South Korea. For this location there was no significant correlation between the estimated monthly dry deposition flux (litterfall + throughfall - wet deposition) (6.7 µg m-2 yr-1) and directly measured dry deposition (9.9 µg m-2 yr-1) likely due primarily to Hg losses from the litterfall collector. Dry deposition fluxes in cold seasons (fall and winter) were lower than in warmer seasons (spring and summer). The volume-weighted mean (VWM) Hg concentrations in both precipitation and throughfall were highest in winter, likely due to increased scavenging by snow events. Since South Korea experiences abundant rainfall in summer, VWM Hg concentrations in summer were lower than in other seasons. Litterfall fluxes were highest in the late fall to early winter, when leaves were dropped from the trees (September to November). The cumulative annual Hg emission flux from soil was 6.8 µg m-2 yr-1. Based on these data, the yearly deposition fluxes of Hg calculated using two input approaches (wet deposition + dry deposition or throughfall + litterfall) were 6.8 and 3.6 µg m-2 yr-1, respectively. This is the first reported study which measured the amount of atmospheric Hg deposited to forested areas in South Korea, and thus our results provide useful information to compare against data related to Hg fate and transport in this part of the world.

  2. Wet deposition of major ions in a rural area impacted by biomass burning emissions

    Science.gov (United States)

    Coelho, Cidelmara H.; Allen, Andrew G.; Fornaro, Adalgiza; Orlando, Eduardo A.; Grigoletto, Tahuana L. B.; Campos, M. Lucia A. M.

    2011-09-01

    This work concerns the influence of industrialized agriculture in the tropics on precipitation chemistry. A total of 264 rain events were sampled using a wet-only collector in central São Paulo State, Brazil, between January 2003 and July 2007. Electroneutrality balance calculations (considering H +, K +, Na +, NH4+, Ca 2+, Mg 2+, Cl -, NO3-, SO42-, F -, PO43-, H 3CCOO -, HCOO -, CO42- and HCO3-) showed that there was an excess of cations (˜15%), which was attributed to the presence of unmeasured organic anion species originating from biomass burning and biogenic emissions. On average, the three ions NH4+, NO 3- and H + were responsible for >55% of the total ion concentrations in the rainwater samples. Concentrations (except of H +) were significantly higher ( t-test; P = 0.05), by between two to six-fold depending on species, during the winter sugar cane harvest period, due to the practice of pre-harvest burning of the crop. Principal component analysis showed that three components could explain 88% of the variance for measurements made throughout the year: PC1 (52%, biomass burning and soil dust resuspension); PC2 (26%, secondary aerosols); PC3 (10%, road transport emissions). Differences between harvest and non-harvest periods appeared to be mainly due to an increased relative importance of road transport/industrial emissions during the summer (non-harvest) period. The volume-weighted mean (VWM) concentrations of ammonium (23.4 μmol L -1) and nitrate (17.5 μmol L -1) in rainwater samples collected during the harvest period were similar to those found in rainwater from São Paulo city, which emphasizes the importance of including rural agro-industrial emissions in regional-scale atmospheric chemistry and transport models. Since there was evidence of a biomass burning source throughout the year, it appears that rainwater composition will continue to be affected by vegetation fires, even after sugar cane burning is phased out as envisaged by recent São Paulo

  3. Parallel measurements of organic and elemental carbon dry (PM1, PM2.5) and wet (rain, snow, mixed) deposition into the Baltic Sea.

    Science.gov (United States)

    Witkowska, Agnieszka; Lewandowska, Anita; Falkowska, Lucyna M

    2016-03-15

    Parallel studies on organic and elemental carbon in PM1 and PM2.5 aerosols and in wet deposition in various forms of its occurrence were conducted in the urbanised coastal zone of the Baltic Sea. The carbon load introduced into the sea water was mainly affected by the form of precipitation. Dry deposition load of carbon was on average a few orders of magnitude smaller than wet deposition. The suspended organic carbon was more effectively removed from the air with rain than snow, while an inverse relationship was found for elemental carbon. However the highest flux of water insoluble organic carbon was recorded in precipitation of a mixed nature. The atmospheric cleaning of highly dissolved organic carbon was observed to be the most effective on the first day of precipitation, while the hydrophobic elemental carbon was removed more efficiently when the precipitation lasted longer than a day.

  4. Influences of in-cloud aerosol scavenging parameterizations on aerosol concentrations and wet deposition in ECHAM5-HAM

    Directory of Open Access Journals (Sweden)

    B. Croft

    2009-10-01

    Full Text Available A diagnostic nucleation scavenging scheme, which determines stratiform cloud scavenging ratios for both aerosol mass and number distributions, based on cloud droplet, and ice crystal number concentrations, is introduced into the ECHAM5-HAM global climate model. This is coupled with a size-dependent in-cloud impaction scavenging parameterization for both cloud droplet-aerosol, and ice crystal-aerosol collisions. Sensitivity studies are presented, which compare aerosol concentrations, and deposition between a variety of in-cloud scavenging approaches, including prescribed fractions, several diagnostic schemes, and a prognostic aerosol cloud processing treatment that passes aerosol in-droplet and in-ice crystal concentrations between model time steps. For one sensitivity study, assuming 100% of the in-cloud aerosol is scavenged into the cloud droplets and ice crystals, the annual global mean accumulation mode number burden is decreased by 65%, relative to a simulation with prognostic aerosol cloud processing. Diagnosing separate nucleation scavenging ratios for aerosol number and mass distributions, as opposed to equating the aerosol mass scavenging to the number scavenging ratios, reduces the annual global mean sulfate burden by near to 10%. The annual global mean sea salt burden is 30% lower for the diagnostic approach, which does not carry aerosol in-droplet and in-crystal concentrations between model time-steps as compared to the prognostic scheme. Implementation of in-cloud impaction scavenging reduced the annual, global mean black carbon burden by 30% for the prognostic aerosol cloud processing scheme. Better agreement with observations of black carbon profiles from aircraft (changes near to one order of magnitude for mixed phase clouds, 210Pb surface layer concentrations and wet deposition, and the geographic distribution of aerosol optical depth are found for the new diagnostic scavenging as compared to prescribed ratio

  5. Wash effect of atmospheric trace metals wet deposition and its source characteristic in subtropical watershed in China.

    Science.gov (United States)

    Gao, Yang; Hao, Zhuo; Yang, Tiantian; He, Nianpeng; Tian, Jing; Wen, Xuefa

    2016-10-01

    In order to better understand air pollution in deve-loping regions, such as China, it is important to investigate the wet deposition behavior of atmospheric trace metals and its sources in the subtropical watershed. This paper studies the seasonal change of trace metal concentrations in precipitation and other potential sources in a typical subtropical watershed (Jiazhuhe watershed) located in the downstream of the Yangtze River of China. The results show that typical crustal elements (Al, Fe) and trace element (Zn) have high seasonal variation patterns and these elements have higher contents in precipitation as compared to other metals in Jiazhuhe watershed. In addition, there is no observed Pb in base flow in this study, and the concentration magnitudes of Al, Ba, Fe, Mn, Sr, and Zn in base flow are significantly higher than that of other metals. During different rainfall events, the dynamic export processes are also different for trace metals. The various trace metals dynamic export processes lead to an inconsistent mass first flush and a significant accumulative variance throughout the rainfall events. It is found that in this region, most of the trace metals in precipitation are from anthropogenic emission and marine aerosols brought by typhoon and monsoon.

  6. Changes in Sport Fish Mercury Concentrations from Food Web Shifts Suggest Partial Decoupling from Atmospheric Deposition in Two Colorado Reservoirs.

    Science.gov (United States)

    Wolff, Brian A; Johnson, Brett M; Lepak, Jesse M

    2017-02-01

    Partial decoupling of mercury (Hg) loading and observed Hg concentrations ([Hg]) in biotic and abiotic samples has been documented in aquatic systems. We studied two Colorado reservoirs to test whether shifts in prey for sport fish would lead to changes in [Hg] independent of external atmospheric Hg deposition. We compared sport fish total mercury concentrations ([T-Hg]) and macroinvertebrate (chironomids and crayfish) methylmercury concentrations ([MeHg]) before and after food web shifts occurred in both reservoirs. We also monitored wet atmospheric Hg deposition and sediment [T-Hg] and [MeHg] at each reservoir. We found rapid shifts in Hg bioaccumulation in each reservoir's sport fish, and these changes could not be attributed to atmospheric Hg deposition. Our study shows that trends in atmospheric deposition, environmental samples (e.g., sediments), and samples of species at the low trophic levels (e.g., chironomids and crayfish) may not accurately reflect conditions that result in fish consumption advisories for high trophic level sport fish. We suggest that in the short-term, monitoring fish [Hg] is necessary to adequately protect human health because natural and anthropogenic perturbations to aquatic food-webs that affect [Hg] in sport fish will continue regardless of trends in atmospheric deposition.

  7. Morphology, conductivity, and wetting characteristics of PEDOT:PSS thin films deposited by spin and spray coating

    Science.gov (United States)

    Zabihi, F.; Xie, Y.; Gao, S.; Eslamian, M.

    2015-05-01

    The goal of this paper is to study the characteristics of PEDOT:PSS thin films and the effects of varying the processing parameters on the structure, functionality, and surface wetting of spun-on and spray-on PEDOT:PSS thin films. PEDOT:PSS is a polymer mixture, which is electrically conductive and transparent and, therefore, is an attractive material for some optoelectronic applications, such as organic and perovskite solar cells. In this work, the films are fabricated using spin coating (a lab-scale method) and spray coating (an up-scalable method). The effects of spinning speed, drying time, and post-annealing temperature on spun-on samples and the effects of the substrate temperature and number of spray passes (deposition layers) on spray-on samples, as well as the effect of precursor solution concentration on both cases are investigated. Various characterization tools, such as AFM, SEM, XRD, confocal laser scanning microscopy (CLSM), and electrical conductivity measurements are used to determine the film roughness, thickness, structure, and morphology. The solution precursor physical data, such as contact angle on glass substrates, viscosity, and interfacial tension, are also obtained within a practical range of temperatures and concentrations. It is found that in both spin and spray coating routes, only well-controlled operating conditions result in the formation of conductive and defect-free PEDOT:PSS films. The formation of PEDOT:PSS thin films with small grains composed of PEDOT forming the core of the grains and PSS forming a shell or coating, which are evenly distributed in a PSS-rich matrix, is favored. Conditions leading to the above-mentioned electrically conductive scenario are identified. Other topics, such as the formation of defects and dewetting, are also elucidated.

  8. Morphology, conductivity, and wetting characteristics of PEDOT:PSS thin films deposited by spin and spray coating

    Energy Technology Data Exchange (ETDEWEB)

    Zabihi, F.; Xie, Y.; Gao, S.; Eslamian, M., E-mail: Morteza.Eslamian@sjtu.edu.cn

    2015-05-30

    Highlights: • Nanostructure of spun-on and spray-on PEDOT:PSS thin films is studied. • A correlation is established between the film nanostructure and electrical conductivity. • Effect of process parameters is studied on the film characteristics. • A high solution concentration, high process temperature and multiple deposition layers are recommended. - Abstract: The goal of this paper is to study the characteristics of PEDOT:PSS thin films and the effects of varying the processing parameters on the structure, functionality, and surface wetting of spun-on and spray-on PEDOT:PSS thin films. PEDOT:PSS is a polymer mixture, which is electrically conductive and transparent and, therefore, is an attractive material for some optoelectronic applications, such as organic and perovskite solar cells. In this work, the films are fabricated using spin coating (a lab-scale method) and spray coating (an up-scalable method). The effects of spinning speed, drying time, and post-annealing temperature on spun-on samples and the effects of the substrate temperature and number of spray passes (deposition layers) on spray-on samples, as well as the effect of precursor solution concentration on both cases are investigated. Various characterization tools, such as AFM, SEM, XRD, confocal laser scanning microscopy (CLSM), and electrical conductivity measurements are used to determine the film roughness, thickness, structure, and morphology. The solution precursor physical data, such as contact angle on glass substrates, viscosity, and interfacial tension, are also obtained within a practical range of temperatures and concentrations. It is found that in both spin and spray coating routes, only well-controlled operating conditions result in the formation of conductive and defect-free PEDOT:PSS films. The formation of PEDOT:PSS thin films with small grains composed of PEDOT forming the core of the grains and PSS forming a shell or coating, which are evenly distributed in a PSS

  9. A model validation study of the washout/rainout contribution of sulfate and nitrate in wet deposition compared with precipitation chemistry data in Japan

    Science.gov (United States)

    Kajino, Mizuo; Aikawa, Masahide

    2015-09-01

    We simulated washout/rainout ratios of non-sea-salt (nss)-SO42- and NO3- using a chemical transport model and compared the estimates with precipitation measurements sampled at 0.5/1 mm intervals at sites located in Kobe (urban), Toyo-oka (suburban), and Tamba (rural) cities, Japan. The 25th and 75th percentile range of the simulated washout contributions was 30-70%. The simulated washout contribution range of NO3- (40-70%) was greater than that of nss-SO42 - (30-60%). There was good agreement between the simulated and observed values, and the observed washout contribution of NO3- was also greater than that of SO42-. The simulated washout contribution range was higher (60-75%) in emission source regions and lower (40-55%) in downwind areas. The wet deposition process is one of the key causes of uncertainty in chemical transport modeling. Comparing model results with such high-frequency precipitation chemistry data has been extremely rare. Thus the current study is providing useful information for evaluating and improving wet deposition modeling and for the better understanding of the wet deposition mechanism.

  10. Continental-scale assessment of long-term trends in wet deposition trajectories: Role of anthropogenic and hydro-climatic drivers

    Science.gov (United States)

    Park, J.; Gall, H. E.; Niyogi, D.; Rao, S.

    2012-12-01

    The global trend of increased urbanization, and associated increased intensity of energy and material consumption and waste emissions, has contributed to shifts in the trajectories of aquatic, terrestrial, and atmospheric environments. Here, we focus on continental-scale spatiotemporal patterns in two atmospheric constituents (nitrate and sulfate), whose global biogeochemical cycles have been dramatically altered by emissions from mobile and fixed sources in urbanized and industrialized regions. The observed patterns in wet deposition fluxes of nitrate and sulfate are controlled by (1) natural hydro-climatic forcing, and (2) anthropogenic forcing (emissions and regulatory control), both of which are characterized by stochasticity and non-stationarity. We examine long-term wet deposition records in the U.S., Europe, and East Asia to evaluate how anthropogenic and natural forcing factors jointly contributed to the shifting temporal patterns of wet deposition fluxes at continental scales. These data offer clear evidence for successful implementation of regulatory controls and widespread adoption of technologies contributed to improving water quality and mitigation of adverse ecological impacts. We developed a stochastic model to project the future trajectories of wet deposition fluxes in emerging countries with fast growing urban areas. The model generates ellipses within which projected wet deposition flux trajectories are inscribed, similar to the trends in observational data. The shape of the ellipses provides information regarding the relative dominance of anthropogenic (e.g., industrial and urban emissions) versus hydro-climatic drivers (e.g., rainfall patterns, aridity index). Our analysis facilitates projections of the trajectory shift as a result of urbanization and other land-use changes, climate change, and regulatory enforcement. We use these observed data and the model to project likely trajectories for rapidly developing countries (BRIC), with a

  11. Impact of Wet Deposition of Black Carbon on Particle Dynamics in Surface Waters of Halong Bay, North Vietnam

    Science.gov (United States)

    Mari, X.; Guinot, B. P.; Thuoc, C. V.; Brune, J.; Lefebvre, J. P.; Raimbault, P.; Niggemann, J.; Dittmar, T.

    2016-02-01

    Black Carbon (BC) is an aerosol emitted during biomass burning and fossil fuel combustion. The atmospheric lifetime of Black Carbon (BC) ranges from a few days in rainy climates up to one month in dry regions, and on a global scale wet deposition of atmospheric BC accounts for about 80% of the BC input to the ocean. The rain-mediated input of BC to the ocean was studied in a coastal site located in a regional hotspot of atmospheric BC concentration, North Vietnam. We monitored changes in atmospheric and marine BC during a 24-h cycle impacted by a short and heavy rainfall event. During the rainfall event, atmospheric BC concentration decreased by a factor of 8 (i.e. from 5230 to 660 µg BC m-3). This cleaning of the air column was immediately followed by a significant increase (by a factor of 2 to 4) of particulate BC (PBC) and POC concentrations in the surface microlayer (SML) and at 1.5 m depth. In the SML, this event was also followed by a significant increase of DOC and dissolved BC (DBC) concentrations. Interestingly, the concentration of DOC decreased by >10% after the rainfall at 1.5 m depth, suggesting an adsorption of DOC onto sinking PBC. Concomitantly with the increase in particulate BC, nutrient concentrations increased by a factor of 2 in the SML, while no change was observed in the underlying water column. After the rainfall, the particle size spectra, measured along the water column with a LISST (Laser In-Situ Scattering and Transmissometry probe), changed in that the concentration of small particles (100 µm) increased. This alteration of the particle size spectra was restricted to a thin layer of about 20 cm thickness, probably corresponding to a BC-enriched layer adsorbing DOC and small particles, and stimulating aggregation during sinking from the surface to deeper water layers. The concentrations of POC, DOC, PBC, DBC and nutrients reached pre-rainfall levels 4 hours after the event.

  12. GNAQPMS-Hg v1.0, a global nested atmospheric mercury transport model: model description, evaluation and application to trans-boundary transport of Chinese anthropogenic emissions

    Directory of Open Access Journals (Sweden)

    H. S. Chen

    2014-10-01

    Full Text Available Atmospheric mercury (Hg is a toxic pollutant and can be transported over the whole globe due to its long lifetime in the atmosphere. For the purpose of assessing Hg hemispheric transport and better characterizing regional Hg pollution, a global nested atmospheric Hg transport model (GNAQPMS-Hg has been developed. In GNAQPMS-Hg, the gas and aqueous phase Hg chemistry representing the transformation among three forms of Hg: elemental mercury (Hg(0, divalent mercury (Hg(II, and primary particulate mercury (Hg(P are calculated. A detailed description of the model, including mercury emissions, gas and aqueous phase chemistry, and dry and wet deposition is given in this study. Worldwide observations including extensive data in China have been collected for model evaluation. Comparison results show that the model reasonably simulates the global mercury budget and the spatial–temporal variation of surface mercury concentrations and deposition. Overall, model predictions of annual total gaseous mercury (TGM and wet deposition agree with observations within a factor of two, and within a factor of five for oxidized mercury and dry deposition. The model performs significantly better in North America and Europe than in East Asia. This can probably be attributed to the large uncertainties in emission inventories, coarse model resolution and to the inconsistency between the simulation and observation periods in East Asia. Compared to the global simulation, the nested simulation shows improved skill at capturing the high spatial variability of Hg concentrations and deposition over East Asia. In particular, the root mean square error (RMSE of simulated Hg wet deposition over East Asia is reduced by 24% in the nested simulation. Model sensitivity studies indicate that Chinese primary anthropogenic emissions account for 30 and 62% of surface mercury concentrations and deposition over China, respectively. Along the rim of the western Pacific, the contributions

  13. Signal and distribution of volatile Mercury (Hg0) in the Marine High Arctic During Polar Summer in the Sequel of Enhanced Atmospheric Deposition of HgⅡ

    Institute of Scientific and Technical Information of China (English)

    Jonas O. Sommar; Maria E. Andersson

    2008-01-01

    @@ 1 Introduction It has been elucidated that high levels of neurotoxic mercury (Hg) in the Arctic is related to a rapid, near-compete depletion of Hg0 (MDE) in the atmospheric boundary-layer occurring episodically during the Polar spring[1].

  14. Timing of wet episodes in Atacama Desert over the last 15 ka. The Groundwater Discharge Deposits (GWD) from Domeyko Range at 25°S.

    Science.gov (United States)

    Sáez, Alberto; Godfrey, Linda V.; Herrera, Christian; Chong, Guillermo; Pueyo, Juan J.

    2016-08-01

    A chronologically robust reconstruction of timing and dynamics of millennial time scale wet episodes encompassing the entire Atacama Desert during the last 15 ka has been constructed. To accomplish this, a new composite paleoclimatic record from Groundwater Discharge Deposits (GWD) in the Sierra de Varas (Domeyko Range, southern Atacama in Chile at 25°S) has been compiled and compared with other published paleohydrologic records from the Atacama region. In Sierra de Varas (SV), three millennial timescale wet climate phases have been characterized: around 14.5 ka cal BP, 12.2-9.8 ka cal BP, and 4.7 ka cal BP to the present day. These wet phases are interpreted from intervals of GWD facies formed during periods when the springs were active. GWD facies include: (1) black organic peat, rooted mudstones and sandstones formed in local wetland environments, and (2) gypsum-carbonate rich layers formed by interstitial growth. GWD intervals alternate with gravelly alluvial material deposited during arid phases. A trend towards less humid conditions during the Late Holocene wet episode characterizes GWD sedimentary series in Sierra the Varas, suggesting the onset of a dry episode over the last few centuries. Around 0.7 ka BP a very short wet episode is recorded in the central part of the desert suggesting this was the time of maximum humidity for the entire late Holocene wet period. A brief arid phase occurred between 1.5 and 2.0 ka BP indicated by the absence of GWD in the Domeyko Range. The paleoclimatic reconstruction encompassing the entire Atacama region shows that both the intensity and occurrence of wetter conditions were governed mainly by the distance to the source of moisture, and secondarily by the elevation of the sites. In the northern Atacama (16-20°S), four wet phases fed by N-NE summer monsoon precipitations have been proposed: Tauca phase (18-14 ka cal BP) and Coipasa phase (13-10 ka cal BP) during the Late Glacial, followed by Early Holocene and Late

  15. Low-Roughness Plasma Etching of HgCdTe Masked with Patterned Silicon Dioxide

    Science.gov (United States)

    Ye, Z. H.; Hu, W. D.; Yin, W. T.; Huang, J.; Lin, C.; Hu, X. N.; Ding, R. J.; Chen, X. S.; Lu, W.; He, L.

    2011-08-01

    A novel mask technique utilizing patterned silicon dioxide films has been exploited to perform mesa etching for device delineation and electrical isolation of HgCdTe third-generation infrared focal-plane arrays (IRFPAs). High-density silicon dioxide films were deposited at temperature of 80°C, and a procedure for patterning and etching of HgCdTe was developed by standard photolithography and wet chemical etching. Scanning electron microscopy (SEM) showed that the surfaces of inductively coupled plasma (ICP) etched samples were quite clean and smooth. Root-mean-square (RMS) roughness characterized by atomic force microscopy (AFM) was less than 1.5 nm. The etching selectivity between a silicon dioxide film and HgCdTe in the samples masked with patterned silicon dioxide films was greater than 30:1. These results show that the new masking technique is readily available and promising for HgCdTe mesa etching.

  16. Ammonia emissions in the United States, European Union, and China derived by high-resolution inversion of ammonium wet deposition data: Interpretation with a new agricultural emissions inventory (MASAGE_NH3)

    Science.gov (United States)

    We use the adjoint of a global 3-D chemical transport model (GEOS-Chem) to optimizeammonia (NH3China by inversion of 2005–2008 network data for NH+4 wet deposition fluxes. Optimized emissions are derive...

  17. Plasma-Enhanced Atomic Layer Deposition of SiN-AlN Composites for Ultra Low Wet Etch Rates in Hydrofluoric Acid.

    Science.gov (United States)

    Kim, Yongmin; Provine, J; Walch, Stephen P; Park, Joonsuk; Phuthong, Witchukorn; Dadlani, Anup L; Kim, Hyo-Jin; Schindler, Peter; Kim, Kihyun; Prinz, Fritz B

    2016-07-13

    The continued scaling in transistors and memory elements has necessitated the development of atomic layer deposited (ALD) of hydrofluoric acid (HF) etch resistant and electrically insulating films for sidewall spacer processing. Silicon nitride (SiN) has been the prototypical material for this need and extensive work has been conducted into realizing sufficiently lower wet etch rates (WERs) as well as leakage currents to meet industry needs. In this work, we report on the development of plasma-enhanced atomic layer deposition (PEALD) composites of SiN and AlN to minimize WER and leakage current density. In particular, the role of aluminum and the optimum amount of Al contained in the composite structures have been explored. Films with near zero WER in dilute HF and leakage currents density similar to pure PEALD SiN films could be simultaneously realized through composites which incorporate ≥13 at. % Al, with a maximum thermal budget of 350 °C.

  18. Climate-driven exceedance of total (wet + dry) nitrogen (N) + sulfur (S) deposition to forest soil over the conterminous U.S

    Science.gov (United States)

    Sun, Jian; Fu, Joshua S.; Lynch, Jason A.; Huang, Kan; Gao, Yang

    2017-06-01

    Nitrogen (N) and sulfur (S) depositions are much mitigated over the conterminous U.S. (CONUS) but deposition exceedance still exists on forest soil. In addition, the empirical approach is usually used but only provides a spatially constant critical load (CL). Therefore, the CL derived from steady-state mass balance equation is used to study the CL exceedance on forest soil over the CONUS. The multimodel mean (MMM) of global climate-chemistry models in 2000s indicates that total (wet + dry) N deposition alone over 10.32% of forest soil exceeds the CL, but a higher percent (30.16%) is observed by the N + S deposition, which highlights the necessity of considering S deposition. In 2050s, less CL-exceeded forest soil is projected and the exceedance amount is lower as well, mainly attributed to the strong reduction of projected NOX and SO2 emissions. By first projecting the future CL due to the climate change, the CL exceedance could further decrease as the air temperature is projected to increase rapidly and lead to higher CL in the future. The CL exceedance by N deposition alone is likely to be dominated by NOy in 2000s but NHX in 2050s because of the enhanced NH3 emission. Moreover, both in 2000s and 2050s, using the CL generated by different aggregation methods can cause up to 33 times difference between the corresponding CL exceedance. This suggests that several regions are under the marginal threat of either N or N + S deposition and different CL can influence the results significantly.

  19. Seasonal variations in metallic mercury (Hg0) vapor exchange over biannual wheat-corn rotation cropland in the North China Plain

    Science.gov (United States)

    Sommar, Jonas; Zhu, Wei; Shang, Lihai; Lin, Che-Jen; Feng, Xinbin

    2016-04-01

    due to displacement of Hg0 present in the surface soil horizon. A more lingering effect of flood irrigation is however suppressed Hg0 soil emissions, which for wet soil ( ˜ 30 % vol) beneath the corn canopy was on average a factor of ˜ 3 lower than that for drier soil (< 10 % vol) within wheat stands. Extrapolation of the campaign Hg0 flux data (mean: 7.1 ng m-2 h-1) to the whole year suggests the wheat-corn rotation cropland to be a net source of atmospheric Hg0. The observed magnitude of annual wet deposition flux ( ˜ 8.8 µg Hg m-2) accounted for a minor fraction of soil Hg0 evasion flux prevailing over the majority of the year. Therefore, we suggest that dry deposition of other forms of airborne Hg constitutes the dominant pathway of Hg input to this local ecosystem and that these deposited forms would be gradually transformed and re-emitted as Hg0 rather than being sequestered here. In addition, after crop harvesting, the practice of burning agricultural residue with considerable Hg content rather than straw return management yields seasonally substantial atmospheric Hg0 emissions from croplands in the NCP region.

  20. Variations in the concentration and isotopic composition of nitrate nitrogen in wet deposition and their relation with meteorological conditions in Xi'an city, Northwest China

    Science.gov (United States)

    Xing, M.; Liu, W.

    2012-12-01

    The characterization of N isotopes in NO3- is an effective method to determine NO3- sources and NOX transformation mechanisms. Xi'an city is located in a semi-arid to arid region and is representative of most cities in the north and Northwest of China. Few studies have been carried out on N isotopes in wet deposition of this region. In this study, 29 wet deposition samples were collected from Xi'an city in northwestern China between March 2008 and May 2009 and analyzed for their volume-weighted NO3- and NH4+ concentrations and N isotopic compositions. Volume-weighted mean concentrations were 3.9 μmol L-1 for NO3- and 13.5 μmol L-1 for NH4+. The wet deposition samples showed pronounced seasonal variation in the N isotopic composition of NO3- with δ15N-NO3- ranging from -2.0‰ to +9.2‰ over the course of a year, with a mean value of +2.6 ± 2.6‰. Higher δ15N-NO3- values were observed in the cool season (November-May, +3.8‰) than in the warm season (June-October, +1.0‰). In autumn and winter in particular, the mean δ15N-NO3- values were clearly different (+0.9‰ and +6.7‰, respectively). Various factors are shown to lead to variation in the δ15N-NO3- values in wet deposition. One effect is changing ratios of N derived from agricultural/soil sources (low δ15N-NO3-, dominant in the warm season) and fossil fuel-derived NOX (high δ15N-NO3-, relatively more important in the cool season). However, in the cool season δ15N-NO3- unexpectedly shows a strong negative correlation with SO2 concentration, which should correlate with fossil fuel combustion inputs. This may be explained by interactions of N-species with other atmospheric pollutants. The results also suggest that temperature may be a significant factor affecting δ15N-NO3-. The NOX reacts in different ways depending on temperature, leading to a correlation of δ15N-NO3- with temperature. Moreover, the effects of dilution cannot be neglected here, as there is clear seasonal variation in

  1. Modeling dry and wet deposition of sulfate, nitrate, and ammonium ions in Jiuzhaigou National Nature Reserve, China using a source-oriented CMAQ model: Part II. Emission sector and source region contributions.

    Science.gov (United States)

    Qiao, Xue; Tang, Ya; Kota, Sri Harsha; Li, Jingyi; Wu, Li; Hu, Jianlin; Zhang, Hongliang; Ying, Qi

    2015-11-01

    A source-oriented Community Multiscale Air Quality (CMAQ) model driven by the meteorological fields generated by the Weather Research and Forecasting (WRF) model was used to study the dry and wet deposition of nitrate (NO3(-)), sulfate (SO4(2-)), and ammonium (NH4(+)) ions in the Jiuzhaigou National Nature Reserve (JNNR), China from June to August 2010 and to identify the contributions of different emission sectors and source regions that were responsible for the deposition fluxes. Contributions from power plants, industry, transportation, domestic, biogenic, windblown dust, open burning, fertilizer, and manure management sources to deposition fluxes in JNNR watershed and four EANET sites are determined. In JNNR, 96%, 82%, and 87% of the SO4(2-), NO3(-) and NH4(+) deposition fluxes are in the form of wet deposition of the corresponding aerosol species. Industry and power plants are the two major sources of SO4(2-) deposition flux, accounting for 86% of the total wet deposition of SO4(2-), and industry has a higher contribution (56%) than that of power plants (30%). Power plants and industry are also the top sources that are responsible for NO3(-) wet deposition, and contributions from power plants (30%) are generally higher than those from industries (21%). The major sources of NH4(+) wet deposition flux in JNNR are fertilizer (48%) and manure management (39%). Source-region apportionment confirms that SO2 and NOx emissions from local and two nearest counties do not have a significant impact on predicted wet deposition fluxes in JNNR, with contributions less than 10%. While local NH3 emissions account for a higher fraction of the NH4(+) deposition, approximately 70% of NH4(+) wet deposition in JNNR originated from other source regions. This study demonstrates that S and N deposition in JNNR is mostly from long-range transport rather than from local emissions, and to protect JNNR, regional emission reduction controls are needed. Copyright © 2015 Elsevier B.V. All

  2. Mechanisms and rates of atmospheric deposition of selected trace elements and sulfate to a deciduous forest watershed. [Roles of dry and wet deposition concentrations measured in Walker Branch Watershed

    Energy Technology Data Exchange (ETDEWEB)

    Lindberg, S.E.; Harriss, R.C.; Turner, R.R.; Shriner, D.S.; Huff, D.D.

    1979-06-01

    The critical links between anthropogenic emissions to the atmosphere and their effects on ecosystems are the mechanisms and rates of atmospheric deposition. The atmospheric input of several trace elements and sulfate to a deciduous forest canopy is quantified and the major mechanisms of deposition are determined. The study area was Walker Branch Watershed (WBW) in eastern Tennessee. The presence of a significant quantity of fly ash and dispersed soil particles on upward-facing leaf and flat surfaces suggested sedimentation to be a major mechanism of dry deposition to upper canopy elements. The agreement for deposition rates measured to inert, flat surfaces and to leaves was good for Cd, SO/sub 4//sup =/, Zn, and Mn but poor for Pb. The precipitation concentrations of H/sup +/, Pb, Mn, and SO/sub 4//sup =/ reached maximum values during the summer months. About 90% of the wet deposition of Pb and SO/sub 4//sup =/ was attributed to scavenging by in-cloud processes while for Cd and Mn, removal by in-cloud scavenging accounted for 60 to 70% of the deposition. The interception of incoming rain by the forest canopy resulted in a net increase in the concentrations of Cd, Mn, Pb, Zn, and SO/sub 4//sup =/ but a net decrease in the concentration of H/sup +/. The source of these elements in the forest canopy was primarily dry deposited aerosols for Pb, primarily internal plant leaching for Mn, Cd, and Zn, and an approximately equal combination of the two for SO/sub 4//sup =/. Significant fractions of the total annual elemental flux to the forest floor in a representative chestnut oak stand were attributable to external sources for Pb (99%), Zn (44%), Cd (42%), SO/sub 4//sup =/ (39%), and Mn (14%), the remainder being related to internal element cycling mechanisms. On an annual scale the dry deposition process constituted a significant fraction of the total atmospheric input. (ERB)

  3. Geochemical investigation of dry- and wet-deposited dust during the same dust-storm event in Harbin, China: Constraint on provenance and implications for formation of aeolian loess

    Science.gov (United States)

    Xie, Yuanyun; Chi, Yunping

    2016-04-01

    A strong dust-storm event occurred in Harbin, China on May 11, 2011. The dry- and wet-deposited dust depositions in this dust-storm event, together with the surface sediments from the potential sources, were collected to study grain size distributions, carbonate content and carbon isotopic composition of carbonate, major element, trace element and rare earth elements (REE), and Sr-Nd isotopic compositions. The results indicate as follows. The dry-deposited dusts are characterized by bimodal grain-size distributions with a fine mode at 3.6 μm and a coarse mode at 28 μm whereas the wet-deposited dusts are indicative of unimodal grain-size modes with a fine mode at 6 μm. The dust-storm depositions are influenced to a certain extent by sedimentary sorting and are of a derivation from the recycled sediments. Based on identifying the immobility of element pairs before constraining sources of dust-storm deposits using geochemical elements, in conjunction with REE and especially Sr-Nd isotopic compositions, the primary and strengthening sources for the dust-storm event were detected, respectively. The Hunsandake Sandy Land as the primary source and the Horqin Sandy Land as the strengthening source were together responsible for the derivation of dust depositions during dust-storm event. The Hunsandake Sandy Land, however, contributes less dust to the dust-storm event in Harbin compared to the Horqin Sandy Land, and the Hulun Buir Sandy Land is undoubtedly excluded from being one of the sources for dust-storm depositions in Harbin. There are not notable differences in geochemical (especially Sr-Nd isotopic) compositions between dry- and wet-deposited dusts, indicating that the wet-deposited dust is of identical derivation to the dry-deposited dust. Based on our observations, it is of interest to suggest that fine and coarse particles in the CLP (Chinese Loess Plateau) loess possibly have the same sources.

  4. Estimation of air to grass -dry and wet deposition rates, velocities, and mass interception factors for iodine for a postulated accidental scenario

    Energy Technology Data Exchange (ETDEWEB)

    Karunakara, N.; Ujwal, P.; Yashodhara, I.; Sudeep Kumara, K. [University Science Instrumentation Centre, Mangalore University (India); Geetha, P.V. [Nuclear Power Corporation of India Limited (India); Dileep, B.N.; Joshi, P.J. [Environmental Survey Laboratory, Kaiga Generating Station (India); Ravi, P.M. [Health Physics Division, Bhabha Atomic Research Centre (India)

    2014-07-01

    Air to grass radionuclide transfer parameters such as dry and wet deposition rates, velocities, and mass interception factors are important basic input parameters for the estimation of radiation dose to the public around a nuclear power plant. We have carried out a study on air to grass transfer of iodine for a postulated emergency situation. A walk-in environmental chamber was designed and fabricated with facilities for exposing the plants grown in pots to controlled levels of radionuclides/stable elements. The temperature, humidity, and airflow inside the environmental chamber can be controlled to required values. The chamber has the facility for generating artificial rainfall. Grass grown in pots was kept inside the environmental chamber. Stable iodine (elemental form) was sublimed and injected into the environmental chamber suddenly to generate known concentration of iodine in the air inside the chamber. This simulated an accidental release of iodine to the environment. The concentration of iodine in the air inside the chamber was monitored continuously by drawing air from the environmental chamber through a bubbling setup (bubbling air through 1% sodium carbonate solution) and the iodine was then separated chemically and the concentration was measured by UV-VIS spectrometry. The concentration of iodine inside the chamber was monitored for every 30 min. The grass was exposed to iodine for 3 h after which the leaves were sampled and analysed for iodine concentration. From the concentration values of iodine in air and grass - the dry deposition rate, deposition velocity, and mass interception rates were estimated. The dry deposition velocity of iodine varied in the range of 0.5x10{sup -5}-3.3x10{sup -5} m s{sup -1} with a mean value of 1.7x10{sup -5} m s{sup -1}. The mass interception factor varied in the range of 0.25-13 m{sup 2} kg{sup -1} with a mean value of 4.2 m{sup 2} kg{sup -1} with respect to fresh weight. The wet deposition velocity varied in the range

  5. Atomic layer deposition of Al{sub 2}O{sub 3} on germanium-tin (GeSn) and impact of wet chemical surface pre-treatment

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Suyog, E-mail: suyog@stanford.edu; Chen, Robert; Harris, James S.; Saraswat, Krishna C. [Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States)

    2013-12-09

    GeSn is quickly emerging as a potential candidate for high performance Si-compatible transistor technology. Fabrication of high-ĸ gate stacks on GeSn with good interface properties is essential for realizing high performance field effect transistors based on this material system. We demonstrate an effective surface passivation scheme for n-Ge{sub 0.97}Sn{sub 0.03} alloy using atomic layer deposition (ALD) of Al{sub 2}O{sub 3}. The effect of pre-ALD wet chemical surface treatment is analyzed and shown to be critical in obtaining a good quality interface between GeSn and Al{sub 2}O{sub 3}. Using proper surface pre-treatment, mid-gap trap density for the Al{sub 2}O{sub 3}/GeSn interface of the order of 10{sup 12} cm{sup −2} has been achieved.

  6. Wet deposition of pesticides and nitrophenols at two sites in Denmark: measurements and contributions from regional sources.

    Science.gov (United States)

    Asman, Willem A H; Jørgensen, Andreas; Bossi, Rossana; Vejrup, Karl V; Mogensen, Betty Bügel; Glasius, Marianne

    2005-05-01

    The concentrations of selected pesticides, of some of their degradation products and nitrophenols in rain were measured at two stations in Denmark in the period January 2000-July 2001. Forty compounds were quantified at least at one station during at least one sampling period. Additionally 17 compounds could be detected but not quantified, and 22 compounds could not be detected at all. The highest depositions of pesticides were observed for pendimethalin and desethylterbuthylazine, which is a degradation product of terbuthylazine. The deposition of the nitrophenols 2,4-dinitrophenol, DNOC, 3-methyl-4-nitrophenol was much higher than that of pesticides. The deposition of 2,4-dinitrophenol was e.g. up to a factor of 40 higher than that of pendimethalin. Atrazine, chloridazon, 2,4-D, dieldrin, disulfoton, fenitrothion, isoproturon, lenacil, metazachlor and propachlor were found in precipitation, although these pesticides are not allowed in Denmark. It can therefore be concluded that they came from abroad and have been transported over at least 60-80 km. For some of these compounds the transport distance is much longer.

  7. Comparison of mercury mass loading in streams to atmospheric deposition in watersheds of Western North America: Evidence for non-atmospheric mercury sources

    Science.gov (United States)

    Domagalski, Joseph L.; Majewski, Michael S.; Alpers, Charles N.; Eckley, Chris S.; Eagles-Smith, Collin A.; Schenk, Liam N.; Wherry, Susan

    2016-01-01

    Annual stream loads of mercury (Hg) and inputs of wet and dry atmospheric Hg deposition to the landscape were investigated in watersheds of the Western United States and the Canadian-Alaskan Arctic. Mercury concentration and discharge data from flow gauging stations were used to compute annual mass loads with regression models. Measured wet and modeled dry deposition were compared to annual stream loads to compute ratios of Hg stream load to total Hg atmospheric deposition. Watershed land uses or cover included mining, undeveloped, urbanized, and mixed. Of 27 watersheds that were investigated, 15 had some degree of mining, either of Hg or precious metals (gold or silver), where Hg was used in the amalgamation process. Stream loads in excess of annual Hg atmospheric deposition (ratio > 1) were observed in watersheds containing Hg mines and in relatively small and medium-sized watersheds with gold or silver mines, however, larger watersheds containing gold or silver mines, some of which also contain large dams that trap sediment, were sometimes associated with lower load ratios (< 0.2). In the non-Arctic regions, watersheds with natural vegetation tended to have low ratios of stream load to Hg deposition (< 0.1), whereas urbanized areas had higher ratios (0.34–1.0) because of impervious surfaces. This indicated that, in ecosystems with natural vegetation, Hg is retained in the soil and may be transported subsequently to streams as a result of erosion or in association with dissolved organic carbon. Arctic watersheds (Mackenzie and Yukon Rivers) had a relatively elevated ratio of stream load to atmospheric deposition (0.27 and 0.74), possibly because of melting glaciers or permafrost releasing previously stored Hg to the streams. Overall, our research highlights the important role of watershed characteristics in determining whether a landscape is a net source of Hg or a net sink of atmospheric Hg.

  8. Comparison of mercury mass loading in streams to atmospheric deposition in watersheds of Western North America: Evidence for non-atmospheric mercury sources.

    Science.gov (United States)

    Domagalski, Joseph; Majewski, Michael S; Alpers, Charles N; Eckley, Chris S; Eagles-Smith, Collin A; Schenk, Liam; Wherry, Susan

    2016-10-15

    Annual stream loads of mercury (Hg) and inputs of wet and dry atmospheric Hg deposition to the landscape were investigated in watersheds of the Western United States and the Canadian-Alaskan Arctic. Mercury concentration and discharge data from flow gauging stations were used to compute annual mass loads with regression models. Measured wet and modeled dry deposition were compared to annual stream loads to compute ratios of Hg stream load to total Hg atmospheric deposition. Watershed land uses or cover included mining, undeveloped, urbanized, and mixed. Of 27 watersheds that were investigated, 15 had some degree of mining, either of Hg or precious metals (gold or silver), where Hg was used in the amalgamation process. Stream loads in excess of annual Hg atmospheric deposition (ratio>1) were observed in watersheds containing Hg mines and in relatively small and medium-sized watersheds with gold or silver mines, however, larger watersheds containing gold or silver mines, some of which also contain large dams that trap sediment, were sometimes associated with lower load ratios (<0.2). In the non-Arctic regions, watersheds with natural vegetation tended to have low ratios of stream load to Hg deposition (<0.1), whereas urbanized areas had higher ratios (0.34-1.0) because of impervious surfaces. This indicated that, in ecosystems with natural vegetation, Hg is retained in the soil and may be transported subsequently to streams as a result of erosion or in association with dissolved organic carbon. Arctic watersheds (Mackenzie and Yukon Rivers) had a relatively elevated ratio of stream load to atmospheric deposition (0.27 and 0.74), possibly because of melting glaciers or permafrost releasing previously stored Hg to the streams. Overall, our research highlights the important role of watershed characteristics in determining whether a landscape is a net source of Hg or a net sink of atmospheric Hg.

  9. Spatial and temporal variability of (7)Be and (210)Pb wet deposition during four successive monsoon storms in a catchment of northern Laos.

    Science.gov (United States)

    Gourdin, E; Evrard, O; Huon, S; Reyss, J-L; Ribolzi, O; Bariac, T; Sengtaheuanghoung, O; Ayrault, S

    2014-10-01

    Fallout radionuclides (7)Be and (210)Pb have been identified as potentially relevant temporal tracers for studying soil particles dynamics (surface vs. subsurface sources contribution; remobilization of in-channel sediment) during erosive events in river catchments. An increasing number of studies compared (7)Be: (210)Pb activity ratio in rainwater and sediment to estimate percentages of freshly eroded particles. However, the lack of data regarding the spatial and temporal variability of radionuclide wet deposition during individual storms has been identified as one of the main gaps in these estimates. In order to determine these key parameters, rainwater samples were collected at three stations during four storms that occurred at the beginning of the monsoon (June 2013) in the Houay Xon mountainous catchment in northern Laos. Rainwater (7)Be and (210)Pb activities measured using very low background hyperpure Germanium detectors ranged from 0.05 to 1.72 Bq L(-1) and 0.02 to 0.26 Bq L(-1), respectively. Water δ(18)O were determined on the same samples. Total rainfall amount of the four sampled storms ranged from 4.8 to 26.4 mm (51 mm in total) at the time-fractionated collection point. Corresponding cumulative (7)Be and (210)Pb wet depositions during the sampling period were 17.6 and 2.9 Bq m(-2), respectively. The (7)Be: (210)Pb activity ratio varied (1) in space from 6 to 9 for daily deposition and (2) in time from 3 to 12 for samples successively collected. Intra-event evolution of rainwater (7)Be and (210)Pb activities as well as δ(18)O highlighted the progressive depletion of local infra-cloud atmosphere radionuclide stock with time (washout), which remains consistent with a Raleigh-type distillation process for water vapour. Intra-storm ratio increasing with time showed the increasing contribution of rainout scavenging. Implications of such variability for soil particle labelling and erosion studies are briefly discussed and recommendations are formulated

  10. Ammonia emissions in the United States, European Union, and China derived by high-resolution inversion of ammonium wet deposition data: Interpretation with a new agricultural emissions inventory (MASAGE_NH3)

    Science.gov (United States)

    We use the adjoint of a global 3-D chemical transport model (GEOS-Chem) to optimizeammonia (NH3European Union, and China by inversion of 2005–2008 network data for NH+4 wet deposition fluxes. Optimized emissions are derive...

  11. Influences of in-cloud aerosol scavenging parameterizations on aerosol concentrations and wet deposition in ECHAM5-HAM

    Directory of Open Access Journals (Sweden)

    B. Croft

    2010-02-01

    Full Text Available A diagnostic cloud nucleation scavenging scheme, which determines stratiform cloud scavenging ratios for both aerosol mass and number distributions, based on cloud droplet, and ice crystal number concentrations, is introduced into the ECHAM5-HAM global climate model. This scheme is coupled with a size-dependent in-cloud impaction scavenging parameterization for both cloud droplet-aerosol, and ice crystal-aerosol collisions. The aerosol mass scavenged in stratiform clouds is found to be primarily (>90% scavenged by cloud nucleation processes for all aerosol species, except for dust (50%. The aerosol number scavenged is primarily (>90% attributed to impaction. 99% of this impaction scavenging occurs in clouds with temperatures less than 273 K. Sensitivity studies are presented, which compare aerosol concentrations, burdens, and deposition for a variety of in-cloud scavenging approaches: prescribed fractions, a more computationally expensive prognostic aerosol cloud processing treatment, and the new diagnostic scheme, also with modified assumptions about in-cloud impaction and nucleation scavenging. Our results show that while uncertainties in the representation of in-cloud scavenging processes can lead to differences in the range of 20–30% for the predicted annual, global mean aerosol mass burdens, and near to 50% for accumulation mode aerosol number burden, the differences in predicted aerosol mass concentrations can be up to one order of magnitude, particularly for regions of the middle troposphere with temperatures below 273 K where mixed and ice phase clouds exist. Different parameterizations for impaction scavenging changed the predicted global, annual mean number removal attributed to ice clouds by seven-fold, and the global, annual dust mass removal attributed to impaction by two orders of magnitude. Closer agreement with observations of black carbon profiles from aircraft (increases near to one order of magnitude for mixed phase clouds

  12. Long-distance transport of Hg, Sb, and As from a mined area, conversion of Hg to methyl-Hg, and uptake of Hg by fish on the Tiber River basin, west-central Italy

    Science.gov (United States)

    Gray, John E.; Rimondi, Valentina; Costagliola, Pilario; Vaselli, Orlando; Lattanzi, Pierfranco

    2014-01-01

    Stream sediment, stream water, and fish were collected from a broad region to evaluate downstream transport and dispersion of mercury (Hg) from inactive mines in the Monte Amiata Hg District (MAMD), Tuscany, Italy. Stream sediment samples ranged in Hg concentration from 20 to 1,900 ng/g, and only 5 of the 17 collected samples exceeded the probable effect concentration for Hg of 1,060 ng/g, above which harmful effects are likely to be observed in sediment-dwelling organisms. Concentrations of methyl-Hg in Tiber River sediment varied from 0.12 to 0.52 ng/g, and although there is no established guideline for sediment methyl-Hg, these concentrations exceeded methyl-Hg in a regional baseline site (Sb (Sb) and for protection against chronic effects to aquatic wildlife (150 μg/L for As and 5.6 μg/L for Sb). Concentrations of Hg in freshwater fish muscle ranged from 0.052–0.56 μg/g (wet weight), mean of 0.17 μg/g, but only 17 % (9 of 54) exceeded the 0.30 μg/g (wet weight) USEPA fish muscle guideline recommended to protect human health. Concentrations of Hg in freshwater fish in this region generally decreased with increasing distance from the MAMD, where fish with the highest Hg concentrations were collected more proximal to the MAMD, whereas all fish collected most distal from Hg mines contained Hg below the 0.30 μg/g fish muscle guideline. Data in this study indicate some conversion of inorganic Hg to methyl-Hg and uptake of Hg in fish on the Paglia River, but less methylation of Hg and Hg uptake by freshwater fish in the larger Tiber River.

  13. Impact of climate change on mercury concentrations and deposition in the eastern United States.

    Science.gov (United States)

    Megaritis, Athanasios G; Murphy, Benjamin N; Racherla, Pavan N; Adams, Peter J; Pandis, Spyros N

    2014-07-15

    The global-regional climate-air pollution modeling system (GRE-CAPS) was applied over the eastern United States to study the impact of climate change on the concentration and deposition of atmospheric mercury. Summer and winter periods (300 days for each) were simulated, and the present-day model predictions (2000s) were compared to the future ones (2050s) assuming constant emissions. Climate change affects Hg(2+) concentrations in both periods. On average, atmospheric Hg(2+) levels are predicted to increase in the future by 3% in summer and 5% in winter respectively due to enhanced oxidation of Hg(0) under higher temperatures. The predicted concentration change of Hg(2+) was found to vary significantly in space due to regional-scale changes in precipitation, ranging from -30% to 30% during summer and -20% to 40% during winter. Particulate mercury, Hg(p) has a similar spatial response to climate change as Hg(2+), while Hg(0) levels are not predicted to change significantly. In both periods, the response of mercury deposition to climate change varies spatially with an average predicted increase of 6% during summer and 4% during winter. During summer, deposition increases are predicted mostly in the western parts of the domain while mercury deposition is predicted to decrease in the Northeast and also in many areas in the Midwest and Southeast. During winter mercury deposition is predicted to change from -30% to 50% mainly due to the changes in rainfall and the corresponding changes in wet deposition.

  14. [Dynamics of nitrogen and sulfur wet deposition in typical forest stand at different spatial levels in Simian Mountain, mid-subtropical region].

    Science.gov (United States)

    Sun, Tao; Ma, Ming; Wang, Ding-yong; Huang, Li-xin

    2014-12-01

    In order to investigate the dynamics of nitrogen and sulfur wet deposition in subtropical forest ecosystem, one typical forest stand, evergreen broad-leaved forest, at Simian Mountain located in Chongqing was selected in this research. Based on field monitoring, effects of precipitation, throughfall, litterfall, and groundwater runoff of the typical forest stand on the quality of water of Simian Mountain were investigated from September 2012 to August 2013. Results showed that the rainfall of Simian Mountain was apparently acidic, with average pH of 4.89 and maximum pH of 5.14. The soil, canopies and trunks could increase pH of precipitation, with soils having the maximum increment, followed by the forest canopy. Forest canopy had the function of adsorption and purification of NO3-, NO2- and SO4(2-), and the average entrapment rate was 56.68%, 45.84% and 35.51%, respectively. Moreover, the degradation of litter was probably the main reason for the increase of ion concentrations in the surface litter water. Forest soils could absorb and neutralize NO3-, SO2- and NH4+, and release NO2-. The evergreen broad-leaf forest of mid-subtropical region had the function of interception on NO3-, NO2-, NH4+ and SO4(2-), and the total entrapment rate was 92.86%, 57.86%, 87.24% and 87.25%, respectively, and it had a certain buffering function for the acid rain.

  15. Nutrient and mercury deposition and storage in an alpine snowpack of the Sierra Nevada, USA

    Directory of Open Access Journals (Sweden)

    C. Pearson

    2015-01-01

    Full Text Available Bi-weekly snowpack core samples were collected at seven sites along two elevation gradients in the Tahoe Basin during two consecutive snow years to evaluate total wintertime snowpack accumulation of nutrients and pollutants in a high elevation watershed of the Sierra Nevada. Additional sampling of wet deposition and detailed snow pit profiles was conducted the following year to compare wet deposition to snowpack storage and assess the vertical dynamics of snowpack chemicals. Results show that on average organic N comprised 48% of all snowpack N, while nitrate (NO3--N and TAN (total ammonia nitrogen made up 25 and 27%, respectively. Snowpack NO3--N concentrations were relatively uniform across sampling sites over the sampling seasons and showed little difference between seasonal wet deposition and integrated snow pit concentrations in agreement with previous studies that identify wet deposition as the dominant source of wintertime NO3--N deposition. However, vertical snow pit profiles showed highly variable concentrations of NO3--N within the snowpack indicative of additional deposition and in snowpack dynamics. Unlike NO3--N, snowpack TAN doubled towards the end of winter and in addition to wet deposition, had a strong dry deposition component. Organic N concentrations in snowpack were highly variable (from 35 to 70% and showed no clear temporal or spatial dependence throughout the season. Integrated snowpack organic N concentrations were up to 2.5 times higher than seasonal wet deposition, likely due to microbial immobilization of inorganic N as evident by coinciding increases of organic N and decreases of inorganic N, in deeper, aged snowpack. Spatial and temporal deposition patterns of snowpack P were consistent with particulate-bound dry deposition inputs and strong impacts from in-basin sources causing up to 6 times enrichment at urban locations compared to remote sites. Snowpack Hg showed little temporal variability and was dominated by

  16. Modeling wet deposition of inorganics over Northeast Asia with MRI-PM/c and the effects of super large sea salt droplets at near-the-coast stations

    Directory of Open Access Journals (Sweden)

    M. Kajino

    2012-06-01

    Full Text Available We conducted a regional-scale simulation (with grid spacing = 60 km over Northeast Asia for the entire year of 2006 by using an aerosol chemical transport model, the lateral and upper boundary concentrations of which we predicted with a global stratospheric and tropospheric chemistry-climate model, with a horizontal resolution of T42 (grid spacing ~300 km and a time resolution of 1 h. The present one-way nested global-through-regional-scale model is called the Meteorological Research Institute – Passive-tracers Model system for atmospheric Chemistry (MRI-PM/c. We evaluated the model performance with respect to the major inorganic components in rain and snow measured by stations of the Acid Deposition Monitoring Network in East Asia (EANET. Through statistical analysis, we show that the model successfully reproduced the regional-scale processes of emission, transport, transformation, and wet deposition of major inorganic species derived from anthropogenic and natural sources, including SO42−, NH4+, NO3, Na+ and Ca2+. Interestingly, the only exception was Na+ in precipitation at near-coastal stations (where the distance from the coast was from 150 to 700 m, concentrations of which were significantly underestimated by the model, by up to a factor of 30. This result suggested that the contribution of short-lived, super-large sea salt droplets (SLSD; D > 10–100 μm was substantial in precipitation samples at stations near the coast of Japan; thus samples were horizontally representative only within the traveling distances of SLSD (from 1 to 10 km. Nevertheless, the calculated effect of SLSD on precipitation pH was very low, a change of about +0.014 on average, even if the ratio of SLSD to all sea salt in precipitation was assumed to be 90%.

  17. 闽北果园生态系统大气氮湿沉降研究%Study on Wet Deposition of Atmospheric Nitrogen in Orchard Ecosystem of Northern Fujian

    Institute of Scientific and Technical Information of China (English)

    刘尔平; 刘桂生; 雷俊杰

    2012-01-01

    研究了2011年3月至2012年2月期间闽北果园生态系统中大气氮素湿沉降浓度、沉降量的变化规律.结果表明:监测期间降水中总氮(TN)、无机氮(TIN)、溶解有机氮(DON)、铵态氮(NH4+-N)和硝态氮(N03- -N)的平均浓度分别为2.11、1.07、1.04、0.65和0.42 mg/L.湿沉降氮量有明显的季节性变化,春、夏季高,秋、冬季低.TN年沉降量为23.19 kg/hm2,其中NH4+ -N、NO3--N和DON年沉降量分别占TN年沉降量的30.60%、20.02%和49.38%.%The wet - deposition concentration and amount of atmospheric nitrogen in the orchard ecosystem of northern Fujian province were studied from May, 2011 to February, 2012. The results indicated that the average concentration of total nitrogen (TN) , total inorganic nitrogen (TIN) , dissolved organic nitrogen ( DON) , ammonium nitrogen ( NH4 - N) and nitrate nitrogen ( NO3 -N ) in the rainwater during monitoring was 2.11, 1. 07, 1.04, 0. 65 and 0.42 mg/L, respectively. The amount of nitrogen wet - deposition had an obvious seasonal change, and it was high in spring and summer, low in autumn and winter. Annual TN wet - deposition amount was 23. 19 kg/hm2 , and the annual wet - deposition amount of NH4 + - N, NO3 - N and DON accounted for 30. 60% , 20.02% and 49. 38% of the annual TN wet -deposition amount, respectively.

  18. Investigating sources of gaseous oxidized mercury in dry deposition at three sites across Florida, USA

    Directory of Open Access Journals (Sweden)

    M. Sexauer Gustin

    2012-07-01

    Full Text Available During 2009–2010, the State of Florida established a series of air quality monitoring stations to collect data for development of a statewide total maximum daily load (TMDL for mercury (Hg. At three of these sites, located near Ft. Lauderdale (DVE, Pensacola (OLF, and Tampa Bay (TPA, passive samplers for the measurement of air Hg concentrations and surrogate surfaces for measurement of Hg dry deposition were deployed. While it is known that Hg in wet deposition in Florida is high compared to the rest of the United States, there is little information on Hg dry deposition. The objectives of the work were to: (1 investigate the utility of passive sampling systems for Hg in an area with low and consistent air concentrations as measured by the Tekran® mercury measurement system, (2 estimate dry deposition of gaseous oxidized Hg, and (3 investigate potential sources. This paper focuses on Objective 3. All sites were situated within 15 km of 1000 MW electricity generating plants (EGPs and major highways. Bi-weekly dry deposition and passive sampler Hg uptake were not directly correlated with the automated Tekran® system measurements, and there was limited agreement between these systems for periods of high deposition. Using diel, biweekly, and seasonal Hg observations, and ancillary data collected at each site, the potential sources of Hg deposited to surrogate surfaces were investigated. With this information, we conclude that there are three major processes/sources contributing to Hg dry deposition in Florida, with these varying as a function of location and time of year. These include: (1 in situ oxidation of locally and regionally derived Hg facilitated by mobile source emissions, (2 indirect and direct inputs of Hg from local EGPs, and (3 direct input of Hg associated with long range transport of air from the Northeastern United States. We also suggest based on the data collected with the Tekran® and passive sampling systems that different

  19. Dry and Wet Atmospheric Deposition of Nitrogen into Shaoguan, Guangdong Province%广东韶关地区大气氮干湿沉降特征研究

    Institute of Scientific and Technical Information of China (English)

    刘思言; 陈瑾; 卢平; 李来胜; 陈中颖

    2014-01-01

    2012年4月─2013年9月利用自动分离干湿沉降的采样器对广东省韶关市降雨和干沉降进行采集,分析样品降雨量、降尘量及氮营养盐干湿沉降浓度,计算各指标干湿沉降通量,利用沉降通量分析其影响因素及季节性变化趋势,为该地区大气氮沉降的通量预测及其环境管理提供支持,并为其生态环境中污染物的控制与减排提供科学依据。结果表明,观测期间总氮干沉降通量、湿沉降通量和总沉降通量平均值分别为47.73、295.7和310.5 kg·km-2·month-1。氨态氮、硝酸盐氮与有机氮干沉降通量平均值分别为17.39、12.98和17.37 kg·km-2·month-1,其湿沉降通量平均值分别为132.4、117.0和46.23 kg·km-2·month-1。总氮湿沉降通量占总氮总沉降通量平均比例为83.19%,说明总氮沉降通量以湿沉降为主。影响因素方面,总氮干沉降通量与降尘量无相关性;湿沉降受降雨量影响较大,所以受雨季影响,韶关地区4─6月总氮湿沉降负荷较大。成分组成上,干沉降中氨态氮平均占总氮比例35.48%,硝酸盐氮平均占27.96%,有机氮平均占36.55%,因此该地区氮营养盐干沉降中以氨态氮和有机氮为主;氮营养盐湿沉降以氨态氮和硝酸盐氮为主,氨态氮平均占总氮比例46.87%,硝酸盐氮平均占40.64%,有机氮平均比例为12.49%,说明该地区湿沉降同时受到农业活动和工业活动的影响。季节变化上,氮营养盐干沉降通量由大到小依次为冬季、春季、秋季、夏季,湿沉降通量春季较高,夏秋两季较低。%To help predicate the atmospheric nitrogen deposition fluxes and provide scientific basises for ecological environment pollution control and abatement assist environmental, the characteristics of atmospheric nitrogen deposition in Shaoguan, Guangdong Province were investigated. In the study, the dry and wet atmospheric nitrogen deposition samples

  20. Atmospheric mercury deposition and its contribution of the regional atmospheric transport to mercury pollution at a national forest nature reserve, southwest China.

    Science.gov (United States)

    Ma, Ming; Wang, Dingyong; Du, Hongxia; Sun, Tao; Zhao, Zheng; Wei, Shiqing

    2015-12-01

    Atmospheric mercury deposition by wet and dry processes contributes to the transformation of mercury from atmosphere to terrestrial and aquatic systems. Factors influencing the amount of mercury deposited to subtropical forests were identified in this study. Throughfall and open field precipitation samples were collected in 2012 and 2013 using precipitation collectors from forest sites located across Mt. Jinyun in southwest China. Samples were collected approximately every 2 weeks and analyzed for total (THg) and methyl mercury (MeHg). Forest canopy was the primary factor on THg and MeHg deposition. Simultaneously, continuous measurements of atmospheric gaseous elemental mercury (GEM) were carried out from March 2012 to February 2013 at the summit of Mt. Jinyun. Atmospheric GEM concentrations averaged 3.8 ± 1.5 ng m(-3), which was elevated compared with global background values. Sources identification indicated that both regional industrial emissions and long-range transport of Hg from central, northeast, and southwest China were corresponded to the elevated GEM levels. Precipitation deposition fluxes of THg and MeHg in Mt. Jinyun were slightly higher than those reported in Europe and North America, whereas total fluxes of MeHg and THg under forest canopy on Mt. Jiuyun were 3 and 2.9 times of the fluxes of THg in wet deposition in the open. Highly elevated litterfall deposition fluxes suggest that even in remote forest areas of China, deposition of atmospheric Hg(0) via uptake by vegetation leaf may be a major pathway for the deposition of atmospheric Hg. The result illustrates that areas with greater atmospheric pollution can be expected to have greater fluxes of Hg to soils via throughfall and litterfall.

  1. Wetting Splashing

    CERN Document Server

    Tsai, Peichun; Dijkstra, Remko; Lohse, Detlef

    2010-01-01

    We present fluid dynamics videos illustrating wetting splashing-produced by water drop impact onto hydrophobic microstructures at high impact velocity ($\\sim 3$ ms$^{-1}$). The substrate consists of regular and transparent microtextures in square or hexagonal lattice, yielding a high contact angle of $\\sim 150 ^\\circ$. Our high speed top-or-bottom view recordings through the transparent surface shed light on the solid-liquid-air interfaces at impact. Despite the superhydrophobicity of the latticed micropillars (of a periodicity of $10 {\\mu}m), water droplet wets a certain central area and moreover entraps an air bubble beneath the droplet. Besides the central wet area, lamella surf on air splashing outward at high impinging velocity. The effects of micropatterns and air pressure on the impact outcome are also examined. We show that microscopic boundary condition, imposed by the solid texture, profoundly influences the macroscopic flow dynamics upon superhydrophobic surfaces at high impinging velocity. In addi...

  2. Chemical thermodynamics of Hg1201 and Hg1223 phases

    Science.gov (United States)

    Tsuchiya, Tetsuo; Fueki, Kazuo; Koyama, Tadashi

    1998-03-01

    The decomposition equilibrium of Hg1201 and Hg1223 was studied using a thermomicrobalance. A thermodynamic diagram representing the stability domains of Hg1201 and Hg1223 was constructed. Using the diagram, it was shown that Hg1201 is metastable at 800°C and that Hg1223 is stable at 660°C due to the formation of an atmosphere of mercury vapor and oxygen formed by the decomposition of excess HgO. Chemical analysis revealed that the valence of Hg is +2 regardless of the oxygen content. The dependence of Tc on the oxygen content was also studied.

  3. Environmental scanning electron microscopy study of the fine structure of the triple line and cassie-wenzel wetting transition for sessile drops deposited on rough polymer substrates.

    Science.gov (United States)

    Bormashenko, Edward; Bormashenko, Yelena; Stein, Tamir; Whyman, Gene; Pogreb, Roman; Barkay, Zahava

    2007-04-10

    The wetting of rough honeycomb micrometrically scaled polymer substrates was studied. A very strong dependence of the apparent contact angle on the drop volume has been established experimentally. The environmental scanning electron microscopy study of the fine structure of the triple line is reported first. The triple line is not smooth and prefers grasping the polymer matrix over air holes. The precursor rim surrounding the drop has been observed. The revealed dependence of the apparent contact angle on the drop volume is explained by the transition between the pure Cassie and combined Wenzel-Cassie wetting regimes, which is induced by capillarity penetration of water into the holes of relief.

  4. Determination of MeHg sources to fish in the St. Louis River, MN, USA, using Hg stable isotopes

    Science.gov (United States)

    Mercury contamination in the Great Lakes region has become a prevalent concern due to elevated methylmercury (MeHg) levels in fish. While atmospheric deposition of Hg is ubiquitous, releases from legacy point-sources give rise to numerous Areas of Concern (AOCs) across the Great ...

  5. The estimated six-year mercury dry deposition across North America

    Science.gov (United States)

    Zhang, Leiming; Wu, Zhiyong; Cheng, Irene; Wright, L. Paige; Olson, Mark L.; Gay, David A.; Risch, Martin R.; Brooks, Steven; Castro, Mark S.; Conley, Gary D.; Edgerton, Eric S.; Holsen, Thomas M.; Luke, Winston; Tordon, Robert; Weiss-Penzias, Peter

    2016-01-01

    Dry deposition of atmospheric mercury (Hg) to various land covers surrounding 24 sites in North America was estimated for the years 2009 to 2014. Depending on location, multiyear mean annual Hg dry deposition was estimated to range from 5.1 to 23.8 μg m–2 yr–1 to forested canopies, 2.6 to 20.8 μg m–2 yr–1 to nonforest vegetated canopies, 2.4 to 11.2 μg m–2 yr–1 to urban and built up land covers, and 1.0 to 3.2 μg m–2 yr–1 to water surfaces. In the rural or remote environment in North America, annual Hg dry deposition to vegetated surfaces is dominated by leaf uptake of gaseous elemental mercury (GEM), contrary to what was commonly assumed in earlier studies which frequently omitted GEM dry deposition as an important process. Dry deposition exceeded wet deposition by a large margin in all of the seasons except in the summer at the majority of the sites. GEM dry deposition over vegetated surfaces will not decrease at the same pace, and sometimes may even increase with decreasing anthropogenic emissions, suggesting that Hg emission reductions should be a long-term policy sustained by global cooperation.

  6. Atmospheric Wet Deposition Characteristics of Nitrogen and Phosphorus Nutrients in Taihu Lake and Contributions to the Lake%太湖氮磷营养盐大气湿沉降特征及入湖贡献率

    Institute of Scientific and Technical Information of China (English)

    余辉; 张璐璐; 燕姝雯; 李焕利; 徐军

    2011-01-01

    To understand seasonal and spatial wet deposition characteristics of nutrients in Taihu Lake during precipitation, more than 230 precipitation samples were collected at ten monitoring sites from August 2009 to July 2010 in different regions around the Taihu Lake basin. Mass concentrations of total nitrogen (TN), dissolved total nitrogen (DTN), nitrate nitrogen (NO3--N), ammonia nitrogen (NH4+-N), total phosphorus (TP), dissolved total phosphorus (DTP) and dissolved inorganic phosphorus (DIP) in the precipitation samples were measured. The precipitation characteristics of nitrogen and phosphorus nutrients in atmospheric wet deposition, the deposition rates and their contributions compared with their counterparts from external loading of rivers to the lake were studied. The results indicated that the annual average mass concentration of TN in the wet deposition was 3. 16 mg/L, in which that of DTN accounted for more than 70% of TN, with a major form of NH4+ -N. The maximum values of TN appeared in the southern lake district, and the minimum in the north. The TP deposition mass concentrations were relatively lower,with an annual average value of 0.08 mg/L. Seasonally, mass concentrations of different forms of nitrogen in wet deposition in the five regions were high in winter and low in summer, although the wet deposition of different forms of nitrogen and phosphorus were all highest in summer. Spatially, the deposition rates of TN were relatively higher in the southern and eastern lake regions. The deposition rates of NH4 + -N and NO3- -N accounted for approximately 30.4% -52. 0% and 31.6%of DTN, respectively, while the deposition rate proportion of DTP to TP varied greatly among these monitoring sites. The annualsettlements of TN and TP in the precipitation were 10,868 and 247 t, respectively, accounting for 18.6% and 11.9% of theannual loading of rivers into Taihu Lake. These settlements could promote eutrophication and have strong impacts on the lakeecosystem.%2009

  7. Mass Independent Fractionation of Hg Isotopes Preserved in the Precambrian

    Science.gov (United States)

    Thibodeau, A. M.; Bergquist, B. A.; Kah, L. C.; Ono, S.; Ghosh, S.; Hazen, R. M.

    2013-12-01

    Mercury (Hg) is a photochemically active, redox-sensitive, chalcophilic metal with complex biogeochemistry that displays a wide range of mass-dependent (MDF) and mass-independent (MIF) stable isotopic fractionation. In the past decade, Hg isotopes have emerged as important tracers of both the sources and cycling of Hg in the modern environment. However, their utility as environmental proxies in ancient rocks remains largely unexplored. The potential of Hg isotopes to inform Precambrian environments derives from the observation that Hg isotopes with odd atomic mass numbers (199Hg and 201Hg) undergo large MIF by the magnetic isotope effect (MIE) and smaller MIF through the nuclear volume effect (NVE). Small MIF produced via NVE has been observed for numerous transformations and is characterized by MIF ratios (Δ199Hg/Δ201Hg) of about 1.6. Large Hg-MIF driven by MIE has been observed during photochemical transformations and is characterized by Δ199Hg/Δ201Hg ratios between 1 and 1.3. This MIF signal is sensitive to a range of environmental conditions, including the amount and type of solar radiation, the presence and type of complexing organic ligands, and the Hg/dissolved organic carbon (DOC) ratio. Thus, it is hoped that Hg-MIF signals may indirectly record changes in atmospheric composition or seawater chemistry if preserved in marine sedimentary records. Previous work has clearly demonstrated that Hg-MIF signals are preserved in Archean and Paleoproterozoic marine shales and massive sulfide deposits. Here, we present evidence that such signals are also preserved in marine shales of mid-Proterozoic age, including the ~1.3 Ga Sulky formation (Dismal Lakes Group, NW Arctic), the ~1.45 Ga Greyson Shale (Belt Basin, Montana), and the ~1.5 Ga Katalsy formation (Kypry Group, Eastern European Platform). We observe that the Greyson shale and shales within the Sulky formation yield negative Hg-MIF with Δ199Hg/Δ201Hg ratios close to 1 and that Kaltasy group sediments

  8. A canopy trimming experiment in Puerto Rico: The response of litter decomposition and nutrient release to canopy opening and debris deposition in a subtropical wet forest

    Science.gov (United States)

    G. Gonzalez; D.J. Lodge; B.A. Richardson; M.J. Richardson

    2014-01-01

    In this study, we used a replicated factorial design to separate the individual and interacting effects of two main components of a severe hurricane – canopy opening and green debris deposition on leaf litter decay in the tabonuco forest in the Luquillo Mountains of Puerto Rico. We quantify changes in percent mass remaining (PMR), the concentration and absolute amounts...

  9. Estimating mercury emission outflow from East Asia using CMAQ-Hg

    Directory of Open Access Journals (Sweden)

    C.-J. Lin

    2009-10-01

    Full Text Available East Asia contributes nearly 50% of the global anthropogenic mercury emissions into the atmosphere. Recently, there are concerns for the long-range transport of mercury from East Asia to North America, which may lead to enhanced dry and wet depositions in North America. In this study, we performed four monthly simulations (January, April, July and October in 2005 using CMAQ-Hg v4.6 in an East Asian model domain. Coupled with a mass balance analysis and a number of emission inventory scenarios, the chemical transport of atmospheric mercury, the seasonal mercury transport budgets and mercury emission outflow from the East Asian region were investigated. The total annual mercury deposition in the region for the modeling year is estimated to be 821 Mg, with 396 Mg contributed by wet deposition and 425 Mg contributed by dry deposition. Regional mercury transport budgets show strong seasonal variability, with a net removal of RGM (7~5 Mg mo−1 and PHg (13~21 Mg mo−1, and a net export of GEM (60~130 Mg mo−1 from the study domain. The annual outflow caused by the East Asian emission is estimated to be in the range of 1369~1671 Mg yr−1, primarily in the form of GEM. This represents about 75% of the total mercury emissions (anthropogenic and natural in the region. The emission outflow from this source region would contribute to 20~30% of mercury deposition in areas remote from anthropogenic emission sources.

  10. Fission products in National Atmospheric Deposition Program—Wet deposition samples prior to and following the Fukushima Dai-Ichi Nuclear Power Plant incident, March 8?April 5, 2011

    Science.gov (United States)

    Wetherbee, Gregory A.; Debey, Timothy M.; Nilles, Mark A.; Lehmann, Christopher M.B.; Gay, David A.

    2012-01-01

    Radioactive isotopes I-131, Cs-134, or Cs-137, products of uranium fission, were measured at approximately 20 percent of 167 sampled National Atmospheric Deposition Program monitoring sites in North America (primarily in the contiguous United States and Alaska) after the Fukushima Dai-Ichi Nuclear Power Plant incident on March 12, 2011. Samples from the National Atmospheric Deposition Program were analyzed for the period of March 8-April 5, 2011. Calculated 1- or 2-week radionuclide deposition fluxes at 35 sites from Alaska to Vermont ranged from 0.47 to 5,100 Becquerels per square meter during the sampling period of March 15-April 5, 2011. No fission-product isotopes were measured in National Atmospheric Deposition Program samples obtained during March 8-15, 2011, prior to the arrival of contaminated air in North America.

  11. Hg-Mask Coronagraph

    Science.gov (United States)

    Bourget, P.; Veiga, C. H.; Vieira Martins, R.; Assus, P.; Colas, F.

    In order to optimize the occulting process of a Lyot coronagraph and to provide a high dynamic range imaging, a new kind of occulting disk has been developed at the National Observatory of Rio de Janeiro. A mercury (Hg) drop glued onto an optical window by molecular cohesion and compressed by a pellicle film is used as the occulting disk. The minimum of the superficial tension potential function provides an optical precision (lambda/100) of the toric free surface of the mercury. This process provides a size control for the adaptation to the seeing conditions and to the apparent diameter of a resolved object, and in the case of adaptive optics, to the Airy diameter fraction needed. The occultation is a three dimensional process near the focal plane on the toric free surface that provides an apodization of the occultation. The Hg-Mask coronagraph has been projected for astrometric observations of faint satellites near to Jovian planets and works since 2000 at the 1.6 m telescope of the Pico dos Dias Observatory (OPD - Brazil).

  12. Mercury in the global atmosphere: Chemistry, deposition, and land-atmosphere interactions

    Science.gov (United States)

    Selin, Noelle Eckley

    This thesis uses a global 3-D chemical transport model (GEOS-Chem), in conjunction with worldwide atmospheric observations, to better understand and quantify biogeochemical cycling and deposition of mercury. GEOS-Chem includes gaseous elemental (Hg(0)), divalent (Hg(II)), and particulate (Hg(P)) mercury in the atmosphere, and includes coupling with the ocean, developed at University of Washington, and with land, developed in this work. Observed concentrations and seasonal variation of total gaseous mercury (TGM) are consistent with photochemical oxidation for Hg(0) partly balanced by in-cloud photochemical reduction of Hg(II). High TGM concentrations from ship cruises in the Northern Hemisphere are not reproduced, implying a problem either in measurements or our understanding of sources. Model results, supported by observations, suggest Hg(II) to be dominant at higher altitudes. Diurnal variability observed at marine sites suggests uptake by sea salt aerosols is a major deposition mechanism. Global biogeochemical cycles of mercury are constructed for pre-industrial and present-day using the first fully-coupled, global 3-D land-atmosphere-ocean mercury model. Atmosphere-surface cycling increases the effective mercury lifetime more than threefold against transfer to long-lived soil and ocean reservoirs. It is estimated that 68% of deposition to the U.S. is anthropogenic, including 16% from the legacy of anthropogenic mercury accumulated in soils and the deep ocean. Observed seasonal variations in U.S. wet deposition are used to constrain redox and deposition processes influencing the fate of North American and international emissions. The model reproduces the seasonal variation and latitudinal gradient of wet deposition flux measured in the eastern U.S., with a maximum in the Southeast and higher fluxes in summer and at lower latitudes. Seasonal variation is attributed to variations in oxidation and wet deposition rates at northern latitudes, and to seasonal

  13. variation in wet deposition of nitrogen from atmosphere in typical areas of Chongqing%重庆典型地区大气湿沉降氮的时空变化

    Institute of Scientific and Technical Information of China (English)

    袁玲; 周鑫斌; 辜夕容; 黄建国

    2009-01-01

    The present experiment was carried out to investigate spatio-temporal changes in wet deposition of nitrogen from atmosphere in Chongqing area. Rainfall in successive three years was collected from three test sites, including a forestry site and two urban sites near and far from city, and analyzed for variable nitrogen concentrations. Total nitrogen (TN) in rainfall ranged from (3.94±0.50) mg L~(-1) to (4.56±1.01) mg L~(-1),averaged (4.27±0.73) mg L~(-1). NH_4~+-N accounted for 44.9%, NO_3~--N for 27.4% and DON (dissolved organic nitrogen) for 27.5% of TN in rainfall, respectively, indicating largest contribution of NH_4~+-N to wet deposition of nitrogen from atmosphere. The concentrations of nitrogen in rainfall varied seasonally, I.e. Winter > summer > spring and autumn. Nitrogen deposition in rainfall tended to decrease from the urban area near the city to forestry site far from city. TN concentrations in rainfall were 4.56 mg L~(-1)(urban area near the city), 4.32 mg L~(-1)(urban area far from city) and 3.94 mg L~(-1)(forestry area), respectively. Even though there were no correlations between nitrogen concentrations (NH_4~+-N、NO_3~--N、DON and TN) in rainfall and the amount of precipitation, wet deposition of nitrogen from atmosphere were positively correlated to the amount of rainfall. The amount of nitrogen deposition from rainfall in Chongqing, which was higher than critical index of nitrogen load in water and probably harmful to water resources in Three Gorge′s Area, varied spatio-temporally due to ground nitrogen emission and the amount of rainfall.%验连续3a采集雨样研究了重庆市郊区和林区大气湿沉降氮的时空变化.结果表明,重庆市近郊区、远郊区和林区3个采样点雨水总氮浓度范围为(3.94±0.50)~(4.56±1.01)mg L~(-1),平均(4.27±0.73)mg L~(-1).NH_4~+-N、NO_3~--N和DON占TN百分比例分别为44.9%、27.4%和27.5%.降雨中NH_4~+-N对氮沉降量的贡献率最大.在时间尺度上,不同季节降

  14. 长江口放射性核素Pu的大气湿沉降初步研究%Atmospheric Wet Deposition of Radionuclide Pu in the Changjiang River Estuary Region

    Institute of Scientific and Technical Information of China (English)

    张克新; 潘少明; 徐仪红; 曹立国; 徐伟; 张威; 郝永佩

    2016-01-01

    Anthropogenic radionuclides (137Cs, 90Sr, and Pu isotopes) released from atmospheric nuclear tests, ma-jor nuclear reactor accidents, and other sources can be detected in the environment in most parts of the world. In particular, as a result of atmospheric nuclear explosions, about 15 PBq of 239,240Pu (1 PBq=1015 Bq) and 0.3 PBq of 238Pu have been globally released into the atmosphere. These radionuclides may be useful tracers of environ-mental changes, such as desertification, erosion and sedimentation processes, in terrestrial regions. Further-more, measurements of radionuclide deposition are useful for several purposes, including the assessment of the effects of radiation from anthropogenic radionuclides on humans. They may also find use as indicators of envi-ronmental events. Most of the current investigations focus on the chemical behaviors such as transfer and diffu-sion in environment, but for the atmospheric wet deposition of radionuclide Pu, the publically available report is very limited in China. In this article, we investigated and quantified preliminarily the 239,240Pu atmospheric de-position in the Changjiang River Estuary Region based on the records of 239,240Pu atmospheric deposition and pre-cipitation in Tokyo in Japan. The results indicated that 239,240Pu atmospheric deposition history in the Changjiang River Estuary Region was similar to that of the whole north hemisphere. The cumulative atmospheric deposi-tion inventory of 239,240Pu was estimated to be 34.556 Bq/m2 in 1957-2005. The maximum annual deposition oc-curred in 1963 after the large-scale atmospheric nuclear weapons testing in 1950s-1960s conducted by the Unit-ed States and former USSR. Annual 239,240Pu deposition decreased in the period from 1963 to 1967 according to the stratospheric residence time of nuclear debris. In the 1970s, the radionuclide deposition observed in the Changjiang River Estuary showed no decrease because of a series of American and Chinese atmospheric nucle

  15. The Corrosion Behavior of Pure Iron under Solid Na2SO4 Deposit in Wet Oxygen Flow at 500 °C

    OpenAIRE

    Yanbing Tang; Li Liu; Lei Fan; Ying Li; Fuhui Wang

    2014-01-01

    The corrosion behavior of pure Fe under a Na2SO4 deposit in an atmosphere of O2 + H2O was investigated at 500 °C by thermo gravimetric, and electrochemical measurements, viz. potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and surface characterization methods viz. X-ray diffraction (XRD), and scanning electron microscope (SEM)/energy dispersive spectroscopy(EDS). The results showed that a synergistic effect occurred between Na2SO4 and O2 + H2O, which significantl...

  16. 缙云山大气氮湿沉降组成及其变化特征%Composition and temporal variation of atmospheric nitrogen wet deposition in Jinyun Mountain, southwestern China

    Institute of Scientific and Technical Information of China (English)

    孙素琪; 王云琦; 王玉杰; 张会兰; 于雷; 唐晓芬; 朱锦奇; 周彬

    2013-01-01

    Field observation of nitrogen wet deposition in Jinyun Mountain,the natural conservation station of southwestern China,was fixed collected by APS-2A precipitation-dust automatic acquisition instrument from May to October 2012,based on which the composition,monthly and seasonal variation of nitrogen wet deposition were analyzed.Results showed that:1) the concentration of NH4+-N was higher than that of NO3--N and DON (dissolved organic nitrogen),indicating that emission load of NH3 within this area was generally high; 2) the major form of atmospheric reactive nitrogen in Jinyun Mountain area was reduced nitrogen NH4+-N,which primarily came from agricultural productivity; 3) the average concentrations of NO3-N,NH4+-N and DON in precipitation were (0.441 ±0.304),(0.821 ±0.480) and (0.203 ± 0.211) mg/L during the monitoring period,respectively,of which the above three nitrogen forms ranked in NH4+-N > NO3--N > DON ; 4) the highest concentrations of NO3--N,NH4+-N and DON all occurred in May,and the average values were (0.642 ± 0.292),(1.273 ± 0.739) and (0.329 ±0.231) kg/hm2,accounted for 29.76%,56.27% and 13.98% of the total nitrogen wet deposition,respectively; 5) nitrogen concentration was weakly correlated with rainfall and rainfall intensity,while the total nitrogen wet deposition presented an obvious linear correlation with the precipitation amount (P <0.01),which demonstrates that nitrogen wet deposition is mainly affected by rainfall,but rainfall and rainfall intensity have little impact on N concentration.%采用APS-2A型降水降尘自动采集仪,定位收集2012年5-10月重庆缙云山自然保护站的湿沉降数据,分析该地区大气氮湿沉降浓度及沉降的组成、月变化及季节变化.结果表明:1)相对于NO3--N和DON(可溶性有机氮),降雨中NH4+-N的质量浓度较高,说明该地区NH3的排放量较高;2)缙云山地区大气活性氮主要是还原态的NH4+-N,其主要来源于农业生产;3)

  17. Wet-Chemical Surface Texturing of Sputter-Deposited ZnO:Al Films as Front Electrode for Thin-Film Silicon Solar Cells

    Directory of Open Access Journals (Sweden)

    Xia Yan

    2015-01-01

    Full Text Available Transparent conductive oxides (TCOs play a major role as the front electrodes of thin-film silicon (Si solar cells, as they can provide optical scattering and hence improved photon absorption inside the devices. In this paper we report on the surface texturing of aluminium-doped zinc oxide (ZnO:Al or AZO films for improved light trapping in thin-film Si solar cells. The AZO films are deposited onto soda-lime glass sheets via pulsed DC magnetron sputtering. Several promising AZO texturing methods are investigated using diluted hydrochloric (HCl and hydrofluoric acid (HF, through a two-step etching process. The developed texturing procedure combines the advantages of the HCl-induced craters and the smaller and jagged—but laterally more uniform—features created by HF etching. In the two-step process, the second etching step further enhances the optical haze, while simultaneously improving the uniformity of the texture features created by the HCl etch. The resulting AZO films show large haze values of above 40%, good scattering into large angles, and a surface angle distribution that is centred at around 30°, which is known from the literature to provide efficient light trapping for thin-film Si solar cells.

  18. Dry and wet atmospheric deposition of organic carbon in coastal and water areas of the northeastern part of the Sea of Azov

    Science.gov (United States)

    Sorokina, V. V.; Soier, V. G.

    2016-09-01

    The paper reports on new data focusing on organic carbon contained in aeolian material and precipitation falling on coastal and water areas of the northeastern part of the Sea of Azov. Atmospheric deposition was sampled in 2006-2014. The particulate organic carbon content varied from 4 to 27% in aeolian dust samples. The concentration of the organic carbon dissolved in rainwater was from 1.6 to 4.3 mg C/L, and from 0.9 to 16.6 mg C/L in snow. The particulate organic carbon content varied from 2 to 43% in snow. Intensity of aeolian dust settling decreased from 178 to 33 mg/m2 per day with distance from a source of dust; in contrast, the relative content of organic matter increased. In a spring-summer season the aeolian organic carbon fluxes varied from 12 to 18 mg C/m2 per day in Rostov-on-Don, from 28 to 48 mg C/m2 per day on the Gulf of Taganrog coast, and from 20 to 80 mg C/m2 per day in the water area of the Gulf of Taganrog.

  19. The Corrosion Behavior of Pure Iron under Solid Na2SO4 Deposit in Wet Oxygen Flow at 500 °C

    Directory of Open Access Journals (Sweden)

    Yanbing Tang

    2014-08-01

    Full Text Available The corrosion behavior of pure Fe under a Na2SO4 deposit in an atmosphere of O2 + H2O was investigated at 500 °C by thermo gravimetric, and electrochemical measurements, viz. potentiodynamic polarization, electrochemical impedance spectroscopy (EIS, and surface characterization methods viz. X-ray diffraction (XRD, and scanning electron microscope (SEM/energy dispersive spectroscopy(EDS. The results showed that a synergistic effect occurred between Na2SO4 and O2 + H2O, which significantly accelerated the corrosion rate of the pure Fe. Briefly, NaFeO2 was formed in addition to the customary Fe oxides; at the same time, H2SO4 gas was produced by introduction of water vapor. Subsequently, an electrochemical corrosion reaction occurred due to the existence of Na2SO4, NaFeO2, and H2O. When this coupled to the chemical corrosion reaction, the progress of the chemical corrosion reaction was promoted and eventually resulted in the acceleration of the corrosion of the pure Fe.

  20. Mercury methylation in paddy soil: source and distribution of mercury species at a Hg mining area, Guizhou Province, China

    Science.gov (United States)

    Zhao, Lei; Anderson, Christopher W. N.; Qiu, Guangle; Meng, Bo; Wang, Dingyong; Feng, Xinbin

    2016-04-01

    Rice paddy plantation is the dominant agricultural land use throughout Asia. Rice paddy fields have been identified as important sites for methylmercury (MeHg) production in the terrestrial ecosystem and a primary pathway of MeHg exposure to humans in mercury (Hg) mining areas. We compared the source and distribution of Hg species in different compartments of the rice paddy during a complete rice-growing season at two different typical Hg-contaminated mining sites in Guizhou province, China: an abandoned site with a high Hg concentration in soil but a low concentration in the atmosphere and a current-day artisanal site with a low concentration in soil but a high concentration in the atmosphere. Our results showed that the flux of new Hg to the ecosystem from irrigation and atmospheric deposition was insignificant relative to the pool of old Hg in soil; the dominant source of MeHg to paddy soil is in situ methylation of inorganic Hg (IHg). Elevated MeHg concentrations and the high proportion of Hg as MeHg in paddy water and the surface soil layer at the artisanal site demonstrated active Hg methylation at this site only. We propose that the in situ production of MeHg in paddy water and surface soil is dependent on elevated Hg in the atmosphere and the consequential deposition of new Hg into a low-pH anoxic geochemical system. The absence of depth-dependent variability in the MeHg concentration in soil cores collected from the abandoned Hg mining site, consistent with the low concentration of Hg in the atmosphere and high pH of the paddy water and irrigation water, suggested that net production of MeHg at this site was limited. We propose that the concentration of Hg in ambient air is an indicator for the risk of MeHg accumulation in paddy rice.

  1. 700 years reconstruction of mercury and lead atmospheric deposition in the Pyrenees (NE Spain)

    Science.gov (United States)

    Corella, J. P.; Valero-Garcés, B. L.; Wang, F.; Martínez-Cortizas, A.; Cuevas, C. A.; Saiz-Lopez, A.

    2017-04-01

    Geochemical analyses in varved lake sediment cores (Lake Montcortès, Pre-Pyrenees) allowed reconstruction of mercury (Hg) and lead (Pb) atmospheric deposition over the past seven centuries in the Pyrenees (NE Spain). Accumulation Rates (AR) from the Middle Ages to the Industrial Period ranged from 2500 to 26130 μg m2.y-1 and 15-152 μg m2.y-1 for Pb and Hg respectively. Significant metal pollution started ca CE 1550 during a period of increased exploitation of ore resources in Spain. Colder and humid conditions in the Pyrenees during the Little Ice Age may have also favoured Hg and Pb atmospheric deposition in the lake. Therefore, the interplay between increased rainfall (wet deposition) and mining activities in the Iberian Peninsula has driven Hg and Pb AR during the Pre-industrial Period. More recently, the use of leaded gasoline in Europe in the mid-20th century may explain the highest Pb AR between CE 1953 and 1971. The highest Hg AR occurred in CE 1940 synchronous with the highest Hg production peak in Almadén mining district (southern Spain) and the Second World War. The record of Hg enrichment in Lake Montcortès shows a decrease during the last decades in Western Europe similar to other regional records and global emission models. This study highlights the exceptional quality of varved sequences to tease apart pollutants depositional mechanisms, identify historical periods of increased atmospheric pollution and provide a historical context for pollutant baseline values to make correct assessments of recent (atmospheric) pollution in lake ecosystems.

  2. Quantitative and simultaneous analysis of the polarity of polycrystalline ZnO seed layers and related nanowires grown by wet chemical deposition

    Science.gov (United States)

    Guillemin, Sophie; Parize, Romain; Carabetta, Joseph; Cantelli, Valentina; Albertini, David; Gautier, Brice; Brémond, Georges; Fong, Dillon D.; Renevier, Hubert; Consonni, Vincent

    2017-03-01

    The polarity in ZnO nanowires is an important issue since it strongly affects surface configuration and reactivity, nucleation and growth, electro-optical properties, and nanoscale-engineering device performances. However, measuring statistically the polarity of ZnO nanowire arrays grown by chemical bath deposition and elucidating its correlation with the polarity of the underneath polycrystalline ZnO seed layer grown by the sol–gel process represents a major difficulty. To address that issue, we combine resonant x-ray diffraction (XRD) at Zn K-edge using synchrotron radiation with piezoelectric force microscopy and polarity-sensitive chemical etching to statistically investigate the polarity of more than 107 nano-objects both on the macroscopic and local microscopic scales, respectively. By using high temperature annealing under an argon atmosphere, it is shown that the compact, highly c-axis oriented ZnO seed layer is more than 92% Zn-polar and that only a few small O-polar ZnO grains with an amount less than 8% are formed. Correlatively, the resulting ZnO nanowires are also found to be Zn-polar, indicating that their polarity is transferred from the c-axis oriented ZnO grains acting as nucleation sites in the seed layer. These findings pave the way for the development of new strategies to form unipolar ZnO nanowire arrays as a requirement for a number of nanoscale-engineering devices like piezoelectric nanogenerators. They also highlight the great advantage of resonant XRD as a macroscopic, non-destructive method to simultaneously and statistically measure the polarity of ZnO nanowire arrays and of the underneath ZnO seed layer.

  3. Quantitative and simultaneous analysis of the polarity of polycrystalline ZnO seed layers and related nanowires grown by wet chemical deposition

    Energy Technology Data Exchange (ETDEWEB)

    Guillemin, Sophie; Parize, Romain; Carabetta, Joseph; Cantelli, Valentina; Albertini, David; Gautier, Brice; Brémond, Georges; Fong, Dillon D.; Renevier, Hubert; Consonni, Vincent

    2017-01-30

    The polarity in ZnO nanowires is an important issue since it strongly affects surface configuration and reactivity, nucleation and growth, electro-optical properties, and nanoscaleengineering device performances. However, measuring statistically the polarity of ZnO nanowire arrays grown by chemical bath deposition and elucidating its correlation with the polarity of the underneath polycrystalline ZnO seed layer grown by the sol–gel process represents a major difficulty. To address that issue, we combine resonant x-ray diffraction (XRD) at Zn K-edge using synchrotron radiation with piezoelectric force microscopy and polarity-sensitive chemical etching to statistically investigate the polarity of more than 107 nano-objects both on the macroscopic and local microscopic scales, respectively. By using high temperature annealing under an argon atmosphere, it is shown that the compact, highly c-axis oriented ZnO seed layer is more than 92% Zn-polar and that only a few small O-polar ZnO grains with an amount less than 8% are formed. Correlatively, the resulting ZnO nanowires are also found to be Zn-polar, indicating that their polarity is transferred from the c-axis oriented ZnO grains acting as nucleation sites in the seed layer. These findings pave the way for the development of new strategies to form unipolar ZnO nanowire arrays as a requirement for a number of nanoscaleengineering devices like piezoelectric nanogenerators. They also highlight the great advantage of resonant XRD as a macroscopic, non-destructive method to simultaneously and statistically measure the polarity of ZnO nanowire arrays and of the underneath ZnO seed layer.

  4. Spatial distribution and accumulation of Hg in soil surrounding a Zn/Pb smelter.

    Science.gov (United States)

    Wu, Qingru; Wang, Shuxiao; Wang, Long; Liu, Fang; Lin, Che-Jen; Zhang, Lei; Wang, Fengyang

    2014-10-15

    Nonferrous metal smelting is an important atmospheric mercury (Hg) emission source that has significant local and global impacts. To quantify the impact of Hg emission from non-ferrous metal smelter on the surrounding soil, an integrated model parameterizing the processes of smelter emission, air dispersion, atmospheric deposition and Hg accumulation in soil was developed. The concentrations of gaseous elemental Hg (GEM) around the smelter and the spatial distribution of Hg in the surrounding soil were measured and compared with the model results. Atmospheric deposition of Hg emitted from the smelter was identified as the main source of Hg accumulation in the surrounding soil. From 1960 to 2011, the smelter emitted approximately 105 t of Hg into the atmosphere, of which 15 t deposited locally and resulted in an increase of Hg concentration in soil from 0.12 to 1.77 mg kg(-1). A detailed examination of wind rose and model data suggested that the area within 1.0-1.5 km northwest and southeast of the smelter was most severely impacted. It was estimated that the smelter operation from 1969 to 1990, when large scale emission controls were not implemented, resulted in 6450 μg m(-2)yr(-1) of Hg net deposition and a model simulated increase of 0.40 mg kg(-1) of Hg accumulation in the soil. During the period from 1991 to 2011, atmospheric Hg emission from the smelter alone increased the average concentration in soil from 0.41 mg kg(-1) to 0.45 mg kg(-1). In the past 50 years, over 86% of Hg emitted from this smelter went into the global pool, indicating the importance of controlling Hg emissions from non-ferrous metal smelters.

  5. Studies on a novel mask technique with high selectivity and aspect-ratio patterns for HgCdTe trenches ICP etching

    Science.gov (United States)

    Ye, Z. H.; Hu, W. D.; Li, Y.; Huang, J.; Yin, W. T.; Lin, C.; Hu, X. N.; Ding, R. J.; Chen, X. S.; Lu, W.; He, L.

    2012-06-01

    A novel mask technique, combining high selectivity silicon dioxide patterns over high aspect-ratio photoresist (PR) patterns has been exploited to perform mesa etching for device delineation and electrical isolation of HgCdTe third-generation infrared focal plane arrays (IRFPAs). High-density silicon dioxide film covering high aspect-ratio PR patterns was deposited at the temperature of 80°C and silicon dioxide film patterns over high aspect-ratio PR patterns of HgCdTe etching samples was developed by standard photolithography and wet chemical etch. Scanning electron microscopy (SEM) shows that the surfaces of inductively coupled plasma (ICP) etched samples are quite clean and smooth. The etching selectivity between the novel mask and HgCdTe of the samples is increased to above 32: 1 while the side-wall impact of etching plasma is suppressed by the high aspect ratio patterns. These results show that the combined patterning of silicon dioxide film and thick PR film is a readily available and promising masking technique for HgCdTe mesa etching.

  6. 含湿量对甲烷湿空气自热重整积碳特性的影响%NUMERICAL SIMULATION ON CARBON DEPOSITION CHARACTERISTICS OF HUMIDITY RATIO ON CH4/WET AIR AUTO-THERMAL REFORMING REACTION

    Institute of Scientific and Technical Information of China (English)

    冉景煜; 涂维峰

    2011-01-01

    Catalytic combustion of hydrocarbon fuels has been considered as an effective method in power MEMS. However, the ca talyst deactivation, mainly caused by carbon deposition, is occurred ubiquity in the catalytic reforming progress. In this paper, the effects of humidity ratio on the CH4/wet air auto-thermal reforming reaction with Ni catalyst on the micro-chamber's surface were simulated. The results show that increasing the humidity ratio will promote the methane reforming reaction. The heat dissipating capacity of auto-thermal reforming and the density of carbon deposition reduce with increasing the humidity ratio. The CH4 conversion rate, density of carbon deposition and mass fraction of H2 were changed very little, they reach 53.1%, 3.07% and 2.40x10-6 kmol/m2respectively while the humidity ratio exceeds 1.20 kg/kg and mixture flow rate is 36 g/h.%微动力装置中碳氢燃料催化燃烧被认为是有效的方法,但燃烧室内燃料催化重整普遍存在由积碳导致的催化剂失活等问题.本文采用数值方法研究了微细腔中甲烷湿空气在镍基催化剂上的自热重整反应,重点分析含湿量对甲烷自热重整反应及积碳特性的影响.结果表明:含湿量将增强甲烷重整反应;自热反应散热量和表面积碳浓度均随含湿量增加而降低.混合物质量流量为36 g/h时,当含湿量d>1.20 kg/kg后,甲烷转化率、氢气质量分数和积碳浓度变化幅度很小,分别接近 53.1%、3.07%和2.40x10-6 kmol/m2.

  7. Dry etched SiO2 Mask for HgCdTe Etching Process

    Science.gov (United States)

    Chen, Y. Y.; Ye, Z. H.; Sun, C. H.; Deng, L. G.; Zhang, S.; Xing, W.; Hu, X. N.; Ding, R. J.; He, L.

    2016-09-01

    A highly anisotropic etching process with low etch-induced damage is indispensable for advanced HgCdTe (MCT) infrared focal plane array (IRFPA) detectors. The inductively coupled plasma (ICP) enhanced reactive ion etching technique has been widely adopted in manufacturing HgCdTe IRFPA devices. An accurately patterned mask with sharp edges is decisive to accomplish pattern duplication. It has been reported by our group that the SiO2 mask functions well in etching HgCdTe with high selectivity. However, the wet process in defining the SiO2 mask is limited by ambiguous edges and nonuniform patterns. In this report, we patterned SiO2 with a mature ICP etching technique, prior to which a thin ZnS film was deposited by thermal evaporation. The SiO2 film etching can be terminated at the auto-stopping point of the ZnS layer thanks to the high selectivity of SiO2/ZnS in SF6 based etchant. Consequently, MCT etching was directly performed without any other treatment. This mask showed acceptable profile due to the maturity of the SiO2 etching process. The well-defined SiO2 pattern and the etched smooth surfaces were investigated with scanning electron microscopy and atomic force microscope. This new mask process could transfer the patterns exactly with very small etch-bias. A cavity with aspect-ratio (AR) of 1.2 and root mean square roughness of 1.77 nm was achieved first, slightly higher AR of 1.67 was also get with better mask profile. This masking process ensures good uniformity and surely benefits the delineation of shrinking pixels with its high resolution.

  8. Hg localisation in Tillandsia usneoides L. (Bromeliaceae), an atmospheric biomonitor

    Energy Technology Data Exchange (ETDEWEB)

    Filho, G.M.A. [Instituto de Pesquisas Jardim Botanico do Rio de Janeiro (Brazil). Programa Zona Costeira; Andrade, L.R.; Farina, M. [Cidade Universitaria, Rio de Janeiro (Brazil). Instituto de Ciencias Biomedicas, Departamento de Anatomia; Malm, O. [Cidade Universitaria, Rio de Janeiro (Brazil). Instituto de Biofisica Carlos Chagas Filho, Laboratorio de Radioisotopos Eduardo Penna Franca

    2002-07-01

    The Spanish moss, Tillandsia usneoides, has been applied as an atmospheric biomonitor of Hg contamination, although the mechanism of metal plant accumulation has not been understood until now. In the present work, analytical scanning electron microscopy (SEM) was used to localize Hg in T. usneoides exposed to a Hg-air-contaminated area during 15 days. After this period, Hg was determined by the flow injection mercury system, and plants were prepared for SEM observation and energy-dispersive X-ray analysis. A concentration of 2702{+-}318{mu}g Hgg{sup -1} was determined in exposed plants. The presented microanalytical results demonstrated that Hg was partly associated with atmospheric particles deposited upon the plant surface, but it was highly absorbed by the scales, stem and leaves surfaces and less absorbed by epidermal cells of T. usneoides. No Hg was detected in mesophyll parenchyma or in vascular system cells. The great surface adsorption area provided by the scales, in addition to the characteristics of T. usneoides morphology, especially of the node region, are suggested to confer the great capability of T. usneoides in Hg holding. (author)

  9. Vaginitis test - wet mount

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/003916.htm Vaginitis test - wet mount To use the sharing features on this page, please enable JavaScript. The vaginitis wet mount test is a test to detect ...

  10. Hydrothermal synthesis of alpha- and beta-HgS nanostructures

    Science.gov (United States)

    Galain, Isabel; María, Pérez Barthaburu; Ivana, Aguiar; Laura, Fornaro

    2017-01-01

    We synthesized HgS nanostructures by the hydrothermal method in order to use them as electron acceptors in hybrid organic-inorganic solar cells. We employed different mercury sources (HgO and Hg(CH3COO)2) and polyvinylpyrrolidone (PVP) or hexadecanethiol (HDT) as stabilizing/capping agent for controlling size, crystallinity, morphology and stability of the obtained nanostructures. We also used thiourea as sulfur source, and a temperature of 180 °C during 6 h. Synthesized nanostructures were characterized by powder X-Ray Diffraction, Diffuse Reflectance Infrared Fourier Transform and Transmission Electron Microscopy. When PVP acts as stabilizing agent, the mercury source has influence on the size -but not in morphology- of the beta-HgS obtained nansostructures. HDT has control over nanostructures' size and depending on the relation Hg:HDT, we obtained a mixture of alpha and beta HgS which can be advantageous in the application in solar cells, due their absorption in different spectral regions. The smallest nanostructures obtained have a mean diameter of 20 nm when using HDT as capping agent. Also, we deposited the aforementioned nanostructures onto flat glass substrates by the spin coating technique as a first approach of an active layer of a solar cell. The depositions were characterized by atomic force microscopy. We obtained smaller particle deposition and higher particle density -but a lower area coverage (5%) - in samples with HDT as capping agent. This work presents promising results on nanostructures for future application on hybrid solar cells. Further efforts will be focused on the deposition of organic-inorganic layers.

  11. Modeling the global atmospheric transport and deposition of mercury to the Great Lakes

    Directory of Open Access Journals (Sweden)

    Mark D. Cohen

    2016-07-01

    Full Text Available Abstract Mercury contamination in the Great Lakes continues to have important public health and wildlife ecotoxicology impacts, and atmospheric deposition is a significant ongoing loading pathway. The objective of this study was to estimate the amount and source-attribution for atmospheric mercury deposition to each lake, information needed to prioritize amelioration efforts. A new global, Eulerian version of the HYSPLIT-Hg model was used to simulate the 2005 global atmospheric transport and deposition of mercury to the Great Lakes. In addition to the base case, 10 alternative model configurations were used to examine sensitivity to uncertainties in atmospheric mercury chemistry and surface exchange. A novel atmospheric lifetime analysis was used to characterize fate and transport processes within the model. Model-estimated wet deposition and atmospheric concentrations of gaseous elemental mercury (Hg(0 were generally within ∼10% of measurements in the Great Lakes region. The model overestimated non-Hg(0 concentrations by a factor of 2–3, similar to other modeling studies. Potential reasons for this disagreement include model inaccuracies, differences in atmospheric Hg fractions being compared, and the measurements being biased low. Lake Erie, downwind of significant local/regional emissions sources, was estimated by the model to be the most impacted by direct anthropogenic emissions (58% of the base case total deposition, while Lake Superior, with the fewest upwind local/regional sources, was the least impacted (27%. The U.S. was the largest national contributor, followed by China, contributing 25% and 6%, respectively, on average, for the Great Lakes. The contribution of U.S. direct anthropogenic emissions to total mercury deposition varied between 46% for the base case (with a range of 24–51% over all model configurations for Lake Erie and 11% (range 6–13% for Lake Superior. These results illustrate the importance of atmospheric

  12. Mercury cadmium telluride (HgCdTe) passivation by advanced thin conformal Al2O3 films

    Science.gov (United States)

    Fu, Richard; Pattison, James; Chen, Andrew; Nayfeh, Osama

    2012-06-01

    HgCdTe passivation process must be performed at low temperature in order to reduce Hg depletion. Low temperature plasma enhanced atomic layer deposition (PE-ALD) is an emerging deposition technology for thin highly conformal films to meet the demand. Room temperature PE-ALD Al2O3 film's passivation on HgCdTe has been studied. Conformal film was investigated through SEM images of the Al2O3 film deposited onto high aspect ratio features dry etched into HgCdTe. Minority carrier lifetime was measured and compared by photoconductive decay transients of HgCdTe before and after deposition. Room temperature ALD Al2O3 film increased the minority carrier lifetime of HgCdTe.

  13. The Upside to Hg-DOM Associations for Water Quality: Removal of Hg from Solution Using Coagulaion with Metal-Based Salts

    Science.gov (United States)

    Henneberry, Y.; Kraus, T. E.; Fleck, J.; Krabbenhoft, D. P.; Horwath, W. R.

    2011-12-01

    This study assessed the potential use of metal-based coagulants to remove dissolved mercury (Hg) from natural waters and provides information regarding the importance of Hg associations with the dissolved organic matter (DOM) fraction and metal hydroxides. Previous research indicated coagulants were not effective at removing Hg from solution; however those studies used high concentrations of Hg, which did not reflect naturally occurring concentrations of Hg. Filtered water collected from an agricultural drain in the Sacramento-San Joaquin Delta (Delta) was treated with three industrial-grade coagulants (ferric chloride, ferric sulfate, and polyaluminum chloride) to determine their efficacy in removing both inroganic (IHg) and methylmercury (MeHg) from the water column. The Delta suffers from elevated surface water Hg concentrations and as a result is listed as an imparied water body. Coagulants removed up to 85% of DOM from solution. In the absence of DOM, all three coagulants released IHg into solution, however in the presence of DOM the coagulants removed up to 97% of IHg and 80% of MeHg. Results suggest that the removal of Hg is mediated by DOM-coagulant interactions. There was a preferential association of IHg with the more aromatic, higher molecular weight fraction of DOM but no such relationship was found for MeHg. This study offers new fundamental insights regarding large-scale removal of Hg at environmentally relevant concentrations. Research using isotopically labeled Hg is providing insight into whether coagulation can remove recently added Hg (e.g. atmospheric deposition) from solution and whether once formed, the floc can remove additional Hg from the water column.

  14. Wet oxidation of quinoline

    DEFF Research Database (Denmark)

    Thomsen, A.B.; Kilen, H.H.

    1998-01-01

    The influence of oxygen pressure (0.4 and 2 MPa). reaction time (30 and 60 min) and temperature (260 and 280 degrees C) on the wet oxidation of quinoline has been studied. The dominant parameters for the decomposition of quinoline were oxygen pressure and reaction temperature. whereas the reaction...... time was less important within the range studied. Nitrifying bacteria were used to measure the inhibition from wet oxidative-treated samples to study the effect of the (wet oxidation) reaction conditions. Wet oxidation made quinoline more toxic to Nitrosomonas. This was observed for Nitrobacter as well....... The combined wet oxidation and biological treatment of reaction products resulted in 91% oxidation of the parent compound to CO2 and water. Following combined wet oxidation and biological treatment the sample showed low toxicity towards Nitrosomonas and no toxicity towards Nitrobacter. (C) 1998 Elsevier...

  15. A Tropical Paradox - High Mercury Deposition, but Low Mercury Bioaccumulation in Northeastern Puerto Rico

    Science.gov (United States)

    Shanley, J. B.; Marvin-DiPasquale, M. C.; Lane, O.; Arendt, W.; Hall, S. J.

    2016-12-01

    At a "clean air" trade winds site in tropical northeastern Puerto Rico, atmospheric total mercury (THg) deposition averaged 28 µg m-2 yr-1, higher than any site in the USA Mercury Deposition Network, driven by efficient capture of upper tropospheric Hg by high rain-forming clouds. The elevated THg in deposition is reflected in high THg concentrations and flux in streams, but assimilation into the local food web was quite low. There are few mammalian or freshwater fish predators on the island, but 30 faunal samples including fly larvae, freshwater shrimp, spiders, tadpoles, coqui frogs, anole lizards, a scorpion, and a boa constrictor had a median THg concentration of 0.032 µg g-1 (dry weight basis), with the three highest values (near 0.14 µg g-1) from spiders. Avian blood THg concentrations (n=31, from 8 species in various foraging guilds) were also quite low, ranging widely from 0.0002 to 0.032 µg g-1 wet weight, with a median of 0.0043 µg g-1. THg levels in biota were severalfold to more than an order of magnitude lower than comparable values in the continental U.S. These results were surprising given the high Hg inputs and watershed features that would seem to favor methylmercury (MeHg) production (Hg(II)-methylation) - high soil moisture with anoxic zones, ample organic matter and sulfur, and year-round warm temperatures. However, organic soil (0-10 cm) along a hillslope to riparian transect averaged only 0.45 ng/g MeHg, with an average MeHg/THg of only 0.34%. Incubations (n=6) to assess methylation and demethylation indicated that rate constants for demethylation were 6-60 fold greater than those for Hg(II)-methylation, and calculated potential rates of demethylation were 3-9 fold greater than those for Hg(II)-methylation. Thus, the apparent paradox may be resolved by the difference between these rates, whereby MeHg degradation outpaces MeHg production in surface soil and sediment. The interplay of these microbial processes shields the island food web

  16. Wetting of flexible fibre arrays.

    Science.gov (United States)

    Duprat, C; Protière, S; Beebe, A Y; Stone, H A

    2012-02-23

    Fibrous media are functional and versatile materials, as demonstrated by their ubiquity both in natural systems such as feathers and adhesive pads and in engineered systems from nanotextured surfaces to textile products, where they offer benefits in filtration, insulation, wetting and colouring. The elasticity and high aspect ratios of the fibres allow deformation under capillary forces, which cause mechanical damage, matting self-assembly or colour changes, with many industrial and ecological consequences. Attempts to understand these systems have mostly focused on the wetting of rigid fibres or on elastocapillary effects in planar geometries and on a fibre brush withdrawn from an infinite bath. Here we consider the frequently encountered case of a liquid drop deposited on a flexible fibre array and show that flexibility, fibre geometry and drop volume are the crucial parameters that are necessary to understand the various observations referred to above. We identify the conditions required for a drop to remain compact with minimal spreading or to cause a pair of elastic fibres to coalesce. We find that there is a critical volume of liquid, and, hence, a critical drop size, above which this coalescence does not occur. We also identify a drop size that maximizes liquid capture. For both wetting and deformation of the substrates, we present rules that are deduced from the geometric and material properties of the fibres and the volume of the drop. These ideas are applicable to a wide range of fibrous materials, as we illustrate with examples for feathers, beetle tarsi, sprays and microfabricated systems.

  17. Mercury accumulation in sediment cores from three Washington state lakes: evidence for local deposition from a coal-fired power plant.

    Science.gov (United States)

    Furl, Chad V; Meredith, Callie A

    2011-01-01

    Mercury accumulation rates measured in age-dated sediment cores were compared at three Washington state lakes. Offutt Lake and Lake St. Clair are located immediately downwind (18 and 28 km, respectively) of a coal-fired power plant and Lake Sammamish is located outside of the immediate area of the plant (110 km). The sites immediately downwind of the power plant were expected to receive increased mercury deposition from particulate and reactive mercury not deposited at Lake Sammamish. Mercury accumulation in cores was corrected for variable sedimentation, background, and sediment focusing to estimate the anthropogenic contribution (Hg(A,F)). Results indicated lakes immediately downwind of the power plant contained elevated Hg(A,F) levels with respect to the reference lake. Estimated fluxes to Lake Sammamish were compared to measured values from a nearby mercury wet deposition collector to gauge the efficacy of the core deconstruction techniques. Total deposition calculated through the sediment core (20.7 μg/m²/year) fell just outside of the upper estimate (18.9 μg/m²/year) of total deposition approximated from the wet deposition collector.

  18. WetVegEurope

    NARCIS (Netherlands)

    Landucci, Flavia; Řezníčková, Marcela; Šumberová, Kateřina; Hennekens, S.M.; Schaminée, J.H.J.

    2015-01-01

    WetVegEurope is a research project (http://www.sci.muni.cz/botany/vegsci/wetveg) whose goal is to provide a synthesized formalized classification of the aquatic and marsh vegetation across Europe at the level of phytosociological associations. In order to achieve the project objective, a WetVegEu

  19. A Comparison of Mathematical Models of Fish Mercury Concentration as a Function of Atmospheric Mercury Deposition Rate and Watershed Characteristics

    Science.gov (United States)

    Smith, R. A.; Moore, R. B.; Shanley, J. B.; Miller, E. K.; Kamman, N. C.; Nacci, D.

    2009-12-01

    Mercury (Hg) concentrations in fish and aquatic wildlife are complex functions of atmospheric Hg deposition rate, terrestrial and aquatic watershed characteristics that influence Hg methylation and export, and food chain characteristics determining Hg bioaccumulation. Because of the complexity and incomplete understanding of these processes, regional-scale models of fish tissue Hg concentration are necessarily empirical in nature, typically constructed through regression analysis of fish tissue Hg concentration data from many sampling locations on a set of potential explanatory variables. Unless the data sets are unusually long and show clear time trends, the empirical basis for model building must be based solely on spatial correlation. Predictive regional scale models are highly useful for improving understanding of the relevant biogeochemical processes, as well as for practical fish and wildlife management and human health protection. Mechanistically, the logical arrangement of explanatory variables is to multiply each of the individual Hg source terms (e.g. dry, wet, and gaseous deposition rates, and residual watershed Hg) for a given fish sampling location by source-specific terms pertaining to methylation, watershed transport, and biological uptake for that location (e.g. SO4 availability, hill slope, lake size). This mathematical form has the desirable property that predicted tissue concentration will approach zero as all individual source terms approach zero. One complication with this form, however, is that it is inconsistent with the standard linear multiple regression equation in which all terms (including those for sources and physical conditions) are additive. An important practical disadvantage of a model in which the Hg source terms are additive (rather than multiplicative) with their modifying factors is that predicted concentration is not zero when all sources are zero, making it unreliable for predicting the effects of large future reductions in

  20. Rainfall Deposition of Mercury and Other Trace Elements to the Northern Gulf of Mexico

    Science.gov (United States)

    Krishnamurthy, N.; Landing, W. M.; Caffrey, J. M.

    2011-12-01

    Event-based (24-hour integrated) rainfall deposition of mercury, trace metals, and major ions has been monitored over the last 6 years at 3 inland locations and at a "Beach" site close to the coast over the past 2 years in the Pensacola Bay watershed to evaluate the temporal and spatial patterns in atmospheric wet deposition. Samples were analyzed for total mercury and a suite of 50 other trace elements. One goal of this project was to attempt to quantify the contribution of local emission sources to atmospheric deposition of mercury and other heavy metals. There were no significant differences in the rainfall Hg flux between the three inland sites or between nearby Mercury Deposition Network monitoring sites along the Gulf Coast. However, the inland sites saw Hg fluxes in the range of 20-46% greater than that of the Beach site for the year 2010 and two of the nearby MDN sites saw a range of 35-71% greater over the first half of 2010 compared to the Beach site. We seek to explain these differences for sites that are relatively close together geographically. Mercury deposition during the summer months is higher than other months due to higher concentrations in the rainfall and higher summer-time rainfall rates throughout the region. Multivariate statistical analysis was used to sort these trace elements into factors that represent potential sources that contribute to the rainfall chemistry. Four significant factors were identified: (1) crustal dust factor (Al, Ba, Co, Cs, Fe, Li, Si), (2) sea-salt factor (Cl, Na, Mg, Sr), (3) Cd/Zn factor (Cd, Cr, Zn, P), and (4) a "pollution" factor (acidity, nitrate, excess-sulfate, ammonia, As, Bi, Hg, Pb, Sb, Se, Sn). Using ratios of Hg to volatile trace elements and excess sulfate, we can estimate that 22-33% of the rainfall mercury fluxes could be the result of emissions from coal combustion in the region while factor analysis suggests slightly over 40%. However, we cannot definitively distinguish the impacts from local vs

  1. Cloud-resolving simulations of mercury scavenging and deposition in thunderstorms

    Directory of Open Access Journals (Sweden)

    U. S. Nair

    2013-10-01

    Full Text Available This study examines dynamical and microphysical features of convective clouds that affect mercury (Hg wet scavenging and concentrations in rainfall. Using idealized numerical model simulations in the Regional Atmospheric Modeling System (RAMS, we diagnose vertical transport and scavenging of soluble Hg species – gaseous oxidized mercury (GOM and particle-bound mercury (HgP, collectively Hg(II – in thunderstorms under typical environmental conditions found in the Northeast and Southeast United States (US. Mercury scavenging efficiencies from various initial altitudes are diagnosed for a case study of a typical strong convective storm in the Southeast US. Assuming that soluble mercury concentrations are initially vertically uniform, the model results suggest that 60% of mercury deposited to the surface in rainwater originates from above the boundary layer (> 2 km. The free troposphere could supply a larger fraction of mercury wet deposition if GOM and HgP concentrations increase with altitude. We use radiosonde observations in the Northeast and Southeast to characterize three important environmental characteristics that influence thunderstorm morphology: convective available potential energy (CAPE, vertical shear (0–6 km of horizontal wind (SHEAR and precipitable water (PW. The Southeast US generally has lower SHEAR and higher CAPE and PW. We then use RAMS to test how PW and SHEAR impact mercury scavenging and deposition, while keeping the initial Hg(II concentrations fixed in all experiments. We found that the mercury concentration in rainfall is sensitive to SHEAR with the nature of sensitivity differing depending upon the PW. Since CAPE and PW cannot be perturbed independently, we test their combined influence using an ensemble of thunderstorm simulations initialized with environmental conditions for the Northeast and Southeast US. These simulations, which begin with identical Hg(II concentrations, predict higher mercury concentrations in

  2. Assessing anthropogenic sources of mercury in soil in Wanshan Hg mining area, Guizhou, China.

    Science.gov (United States)

    Dai, Zhihui; Feng, Xinbin; Zhang, Chao; Wang, Jingfu; Jiang, Taiming; Xiao, Houjun; Li, Yu; Wang, Xun; Qiu, Guangle

    2013-11-01

    Long-term mining and smelting activities brought a series of environmental issues into soils in Wanshan mercury (Hg) mining area (WMMA), Guizhou, China. Several studies have been published on the concentrations of Hg in local soils, but a comprehensive assessment of the mass of Hg in soil induced by anthropogenic activities, as presented in this paper, has not been previously conducted. Three districts of WMMA were chosen as the study areas. We summarized previous published data and sampled 14 typical soil profiles to analyze the spatial and vertical distributions of Hg in soil in the study areas. The regional geologic background, direct and indirect Hg deposition, and Hg-polluted irrigation water were considered as the main sources of Hg contaminations in local soils. Furthermore, the enrichment factor (EF) method was applied to assess the extent of anthropogenic input of Hg to soil. Titanium (Ti) was chosen to be the reference element to calculate the EF. Generally, the elevated values of EF were observed in the upper soil layers and close to mine wastes. The total budget of Hg in soil contributed from anthropogenic sources was estimated to be 1,227 t in arable soil and 75 t in natural soil. Our data showed that arable soil was the major sink of anthropogenic Hg in the study area.

  3. Wetting Transition in Water

    Science.gov (United States)

    Friedman, S. R.; Khalil, M.; Taborek, P.

    2013-11-01

    Optical images were used to study the wetting behavior of water on graphite, sapphire, and quartz along the liquid vapor coexistence curve from room temperature to 300°C. Wetting transitions were identified by the temperature at which the contact angle decreased to zero and also by the disappearance of dropwise condensation. These two methods yielded consistent values for the wetting temperatures, which were 185°C, 234°C, and 271°C for water on quartz, sapphire, and graphite, respectively. We compare our results with the theoretical predictions based on a simplified model of the water-substrate potential and sharp interfaces.

  4. Chemical thermodynamics of the Hg1212 phase

    Science.gov (United States)

    Tsuchiya, Tetsuo; Fueki, Kazuo

    1997-02-01

    The single phase of Hg1212 was synthesized by the simple oxide method using starting materials containing HgO 16% in excess. Stability regions of Hg1212 and pure HgO were determined by measuring the decomposition temperature as a function of oxygen partial pressure, and thermodynamic diagrams showing the stability domains of HgO and Hg1212 were constructed. The thermodynamical condition of formation of Hg1212 was discussed using the diagrams. It was found by chemical analysis that the valence of Hg is always 2 + and the valence of Ce changes with the oxygen content. TC (zero) changed from 122 to 118 K when the oxygen content was increased from 6.10 to 6.22.

  5. Atmospheric Deposition: Sampling Procedures, Analytical Methods, and Main Recent Findings from the Scientific Literature

    Directory of Open Access Journals (Sweden)

    M. Amodio

    2014-01-01

    Full Text Available The atmosphere is a carrier on which some natural and anthropogenic organic and inorganic chemicals are transported, and the wet and dry deposition events are the most important processes that remove those chemicals, depositing it on soil and water. A wide variety of different collectors were tested to evaluate site-specificity, seasonality and daily variability of settleable particle concentrations. Deposition fluxes of POPs showed spatial and seasonal variations, diagnostic ratios of PAHs on deposited particles, allowed the discrimination between pyrolytic or petrogenic sources. Congener pattern analysis and bulk deposition fluxes in rural sites confirmed long-range atmospheric transport of PCDDs/Fs. More and more sophisticated and newly designed deposition samplers have being used for characterization of deposited mercury, demonstrating the importance of rain scavenging and the relatively higher magnitude of Hg deposition from Chinese anthropogenic sources. Recently biological monitors demonstrated that PAH concentrations in lichens were comparable with concentrations measured in a conventional active sampler in an outdoor environment. In this review the authors explore the methodological approaches used for the assessment of atmospheric deposition, from the analysis of the sampling methods, the analytical procedures for chemical characterization of pollutants and the main results from the scientific literature.

  6. Adsorption and wetting.

    NARCIS (Netherlands)

    Schlangen, L.J.M.

    1995-01-01

    Adsorption and wetting are related phenomena. In order to improve knowledge of both and their relations, experiments, thermodynamics and a theoretical interpretation have been connected, starring n-alkanes.Starting from the Gibbs adsorption equation thermodynamic relations between vapour adsorption

  7. Wet hydrate dissolution plant

    OpenAIRE

    Stanković Mirjana S.; Kovačević Branimir T.; Pezo Lato L.

    2003-01-01

    The IGPC Engineering Department designed basic projects for a wet hydrate dissolution plant, using technology developed in the IGPC laboratories. Several projects were completed: technological, machine, electrical, automation. On the basis of these projects, a production plant with capacity of 50,000 t/y was manufactured, at "Zeolite Mira", Mira (VE), Italy, in 1997, for increasing detergent zeolite production from 50,000 to 100,000 t/y. Several goals were realized by designing a wet hydrate ...

  8. Cloud-resolving simulations of mercury scavenging and deposition in thunderstorms

    Directory of Open Access Journals (Sweden)

    U. S. Nair

    2013-02-01

    Full Text Available This study examines dynamical and microphysical features of convective clouds that affect mercury (Hg wet scavenging and concentrations in rainfall. Using idealized numerical model simulations in the Regional Atmospheric Modeling System (RAMS, we diagnose vertical transport and scavenging of soluble Hg species in thunderstorms under typical environmental conditions found in the Northeast and Southeast United States (US. Three important environmental characteristics that impact thunderstorm morphology were studied: convective available potential energy (CAPE, vertical shear (0���6 km of horizontal wind (SHEAR and precipitable water (PW.

    We find that in a strong convective storm in the Southeast US that about 40% of mercury in the boundary layer (0–2 km can be scavenged and deposited to the surface. Removal efficiencies are 35% or less in the free troposphere and decline with altitude. Nevertheless, if we assume that soluble Hg species are initially uniformly mixed vertically, then about 60% deposited mercury deposited by the thunderstorm originates in the free troposphere.

    For a given CAPE, storm morphology and Hg deposition respond to SHEAR and PW. Experiments show that the response of mercury concentration in rainfall to SHEAR depends on the amount of PW. For low PW, increasing SHEAR decreases mercury concentrations in high-rain amounts (>13 mm. However, at higher PW values, increasing SHEAR decreases mercury concentrations for all rainfall amounts. These experiments suggest that variations in environmental characteristics relevant to thunderstorm formation and evolution can also contribute to geographical difference in wet deposition of mercury.

    An ensemble of thunderstorm simulations was also conducted for different combinations of CAPE, SHEAR and PW values derived from radiosonde observations at five sites in the Northeast United States (US and at three sites in the Southeast US. Using identical initial

  9. New technique for quantification of elemental Hg in mine wastes and its implications for mercury evasion into the atmosphere.

    Science.gov (United States)

    Jew, Adam D; Kim, Christopher S; Rytuba, James J; Gustin, Mae S; Brown, Gordon E

    2011-01-15

    Mercury in the environment is of prime concern to both ecosystem and human health. Determination of the molecular-level speciation of Hg in soils and mine wastes is important for understanding its sequestration, mobility, and availability for methylation. Extended X-ray absorption fine structure (EXAFS) spectroscopy carried out under ambient P-T conditions has been used in a number of past studies to determine Hg speciation in complex mine wastes and associated soils. However, this approach cannot detect elemental (liquid) mercury in Hg-polluted soils and sediments due to the significant structural disorder of liquid Hg at ambient-temperature. A new sample preparation protocol involving slow cooling through the crystallization temperature of Hg(0) (234 K) results in its transformation to crystalline α-Hg(0). The presence and proportion of Hg(0), relative to other crystalline Hg-bearing phases, in samples prepared in this way can be quantified by low-temperature (77 K) EXAFS spectroscopy. Using this approach, we have determined the relative concentrations of liquid Hg(0) in Hg mine wastes from several sites in the California Coast Range and have found that they correlate well with measured fluxes of gaseous Hg released during light and dark exposure of the same samples, with higher evasion ratios from samples containing higher concentrations of liquid Hg(0). Two different linear relationships are observed in plots of the ratio of Hg emission under light and dark conditions vs % Hg(0), corresponding to silica-carbonate- and hot springs-type Hg deposits, with the hot springs-type samples exhibiting higher evasion fluxes than silica-carbonate type samples at similar Hg(0) concentrations. Our findings help explain significant differences in Hg evasion data for different mine sites in the California Coast Range.

  10. New technique for quantification of elemental hg in mine wastes and its implications for mercury evasion into the atmosphere

    Science.gov (United States)

    Jew, A.D.; Kim, C.S.; Rytuba, J.J.; Gustin, M.S.; Brown, Gordon E.

    2011-01-01

    Mercury in the environment is of prime concern to both ecosystem and human health. Determination of the molecular-level speciation of Hg in soils and mine wastes is important for understanding its sequestration, mobility, and availability for methylation. Extended X-ray absorption fine structure (EXAFS) spectroscopy carried out under ambient P-T conditions has been used in a number of past studies to determine Hg speciation in complex mine wastes and associated soils. However, this approach cannot detect elemental (liquid) mercury in Hg-polluted soils and sediments due to the significant structural disorder of liquid Hg at ambient-temperature. A new sample preparation protocol involving slow cooling through the crystallization temperature of Hg(0) (234 K) results in its transformation to crystalline ??-Hg(0). The presence and proportion of Hg(0), relative to other crystalline Hg-bearing phases, in samples prepared in this way can be quantified by low-temperature (77 K) EXAFS spectroscopy. Using this approach, we have determined the relative concentrations of liquid Hg(0) in Hg mine wastes from several sites in the California Coast Range and have found that they correlate well with measured fluxes of gaseous Hg released during light and dark exposure of the same samples, with higher evasion ratios from samples containing higher concentrations of liquid Hg(0). Two different linear relationships are observed in plots of the ratio of Hg emission under light and dark conditions vs % Hg(0), corresponding to silica-carbonate- and hot springs-type Hg deposits, with the hot springs-type samples exhibiting higher evasion fluxes than silica-carbonate type samples at similar Hg(0) concentrations. Our findings help explain significant differences in Hg evasion data for different mine sites in the California Coast Range. ?? 2011 American Chemical Society.

  11. Using Simple Science to Influence Corporate Responsibility—A Lesson from Mercury (Hg)

    Science.gov (United States)

    Filippelli, G. M.

    2016-12-01

    Mercury (Hg) is a powerful neurotoxin with wide environmental distribution. Typical population exposure to Hg comes from fish consumption, with fish being the final ecological endpoint of Hg magnification after a series of biogeochemical processes. The emission of Hg from coal-fired power plants has been strongly implicated as a key source of environmental Hg, and thus the target for various public policy initiatives in the US and abroad. We conducted a study of Hg distribution in surface soils over a broad area of central Indiana (US) to understand the major sources of Hg to local fish, and to assess the potential role of policy compliance in reducing Hg. We found a plume-like distribution pattern for soil Hg, with values exceeding 400 ppb Hg in the heart of the plume, and reducing to background concentration of about 30 ppb outside of the plume. The plume covered hundreds of square kilometers, was centered directly over the downtown area of Indianapolis (a city of roughly 1 million inhabitants), and could be roughly backtracked to a source in the southwest corner of the city, coincident with a large coal-fired utility plant that has the highest reported emissions of Hg in the area. Evidence of this link between a local source of Hg and net Hg deposition, with related implications for Hg runoff to local stream, biomagnification to fish, and fish consumption advisories was reported in regional newspapers and eventually published in scientific journals. But importantly, these findings were used by an NGO (the Beyond Coal campaign by Indiana branch of the Sierra Club) at a critical time to influence a decision by the owner of the power plant of whether to comply with the Hg policy rule by either adding higher technology scrubbing technologies to the plant or simply to convert the plant over to natural gas as the fuel source (a costlier choice upfront). The utility chose the latter option, and with the permanent elimination of Hg emissions, the net measurable effects

  12. Novel methodology for the study of mercury methylation and reduction in sediments and water using 197Hg radiotracer.

    Science.gov (United States)

    Ribeiro Guevara, Sergio; Zizek, Suzana; Repinc, Urska; Pérez Catán, Soledad; Jaćimović, Radojko; Horvat, Milena

    2007-03-01

    increase in specific activity with respect to natural mercury targets was obtained. When this high specific activity tracer is employed, mercury methylation and reduction experiments with minimum mercury additions are feasible. Tracer recovery in methylation experiments (associated with Me197Hg production from 197Hg2+ spike, but also with Hg2+ contamination and Me197Hg artefacts) with marine sediments was about 0.005% g-1 WS (WS: wet sediment) after 20 h incubation with mercury additions of 0.05 ng g-1 WS, which is far below natural mercury levels. In this case, the amount of Hg2+ reduced to Hg0 (expressed as the percent 197Hg0 recovered with respect to the 197Hg2+ added) varied from 0.13 to 1.6% g-1 WS. Me197Hg production from 197Hg2+ spike after 20 h of incubation of freshwater sediment ranged from 0.02 to 0.13% g-1 WS with mercury additions of 2.5 ng g-1 WS, which is also far below natural levels. 197Hg0 recoveries were low, 0.0058+/-0.0013% g-1 WS, but showed good reproducibility in five replicates. Me197Hg production from 197Hg2+ spiked in freshwater samples ranged from 0.1 to 0.3% over a period of three days with mercury additions of 10 ng L-1. A detection limit of 0.05% for Me197Hg production from 197Hg2+ spike was obtained in seawater in a 25 h incubation experiment with mercury additions of 12 ng L-1.

  13. Sources and cycling of mercury in the paleo Arctic Ocean from Hg stable isotope variations in Eocene and Quaternary sediments

    Science.gov (United States)

    Gleason, J. D.; Blum, J. D.; Moore, T. C.; Polyak, L.; Jakobsson, M.; Meyers, P. A.; Biswas, A.

    2017-01-01

    Mercury stable isotopic compositions were determined for marine sediments from eight locations in the Arctic Ocean Basin. Mass dependent fractionation (MDF) and mass independent fractionation (MIF) of Hg stable isotopes were recorded across a variety of depositional environments, water depths, and stratigraphic ages. δ202Hg (MDF) ranges from -2.34‰ to -0.78‰; Δ199Hg (MIF) from -0.18‰ to +0.12‰; and Δ201Hg (MIF) from -0.29‰ to +0.05‰ for the complete data set (n = 33). Holocene sediments from the Chukchi Sea and Morris Jesup Rise record the most negative Δ199Hg values, while Pleistocene sediments from the Central Arctic Ocean record the most positive Δ199Hg values. The most negative δ202Hg values are recorded in Pleistocene sediments. Eocene sediments (Lomonosov Ridge) show some overlap in their Hg isotopic compositions with Quaternary sediments, with a sample of the Arctic Ocean PETM (56 Ma) most closely matching the average Hg isotopic composition of Holocene Arctic marine sediments. Collectively, these data support a terrestrially-dominated Hg source input for Arctic Ocean sediment through time, although other sources, as well as influences of sea ice, atmospheric mercury depletion events (AMDEs), and anthropogenic Hg (in core top samples) on Hg isotopic signatures must also be considered.

  14. Wet storage integrity update

    Energy Technology Data Exchange (ETDEWEB)

    Bailey, W.J.; Johnson, A.B. Jr.

    1983-09-01

    This report includes information from various studies performed under the Wet Storage Task of the Spent Fuel Integrity Project of the Commercial Spent Fuel Management (CSFM) Program at Pacific Northwest Laboratory. An overview of recent developments in the technology of wet storage of spent water reactor fuel is presented. Licensee Event Reports pertaining to spent fuel pools and the associated performance of spent fuel and storage components during wet storage are discussed. The current status of fuel that was examined under the CSFM Program is described. Assessments of the effect of boric acid in spent fuel pool water on the corrosion and stress corrosion cracking of stainless steel and the stress corrosion cracking of stainless steel piping containing stagnant water at spent fuel pools are discussed. A list of pertinent publications is included. 84 references, 21 figures, 11 tables.

  15. Wrinkling of wet paper

    Science.gov (United States)

    Kim, Ho-Young; Kim, Jungchul; Mahadevan, L.

    2011-11-01

    It is a mundane experience that paper stained with water wrinkles. It is because a wetted portion of paper, which swells due to the hygroexpansive nature of the cellulose fiber network, deforms out of its original plane. Here we quantify the dynamics of wrinkling of wet paper coupled to the capillary imbibition of water into paper using a combination of experiment and theory. While supplying water from a capillary tube that touches the center of a paper strip, we measure the spreading rate of the wet area, wait time for the out-of-plane buckling, and temporal growth of a wrinkling magnitude. Using a theoretical model assuming a linear increase of the strain and an exponential decay of the elastic modulus with the water concentration, we construct scaling laws to predict the simultaneous capillary imbibition and wrinkling rates. This work was supported by the Wyss Institute of Harvard University.

  16. Distribution and air-sea exchange of mercury (Hg) in polluted marine environments

    Science.gov (United States)

    Bagnato, E.; Sprovieri, M.; Bitetto, M.; Bonsignore, M.; Calabrese, S.; Di Stefano, V.; Oliveri, E.; Parello, F.; Mazzola, S.

    2012-04-01

    measured during the first cruise ranges from about 110 to 1500 ng · m-2day-1. This range is 1-2 order of magnitude higher than most of marine environments (Pacific Ocean, Mediterranean Sea, Artic Ocean) and some important polluted marine areas, such as the Tokyo Bay (19-259 ng · m-2day-1)b and the Yellow Sea (156-722 ng · m-2day-1)c. Further estimates on Hg atmospheric deposition flux (wet and dry) and biomonitoring are required for finally assessing a mass balance of Hg in Augusta basin. aLindberg et al., 2007. A Journal of the Human Environment, 3, 19-33. bNarukawa et al., 2006. Journal of Oceanography, 62, 249-257. cCi et al., 2011. Atmosphere Chemistry and Physics, 11, 2881-2892.

  17. Hg and As Minerals in Fluid Inclusions from the Williams Mine, Hemlo, and Their Genetic Implications

    Institute of Scientific and Technical Information of China (English)

    LU HUANZHANG(卢焕章); JAYANTA. GUHA; DON. C. HARRIS

    2002-01-01

    The Hemlo mineralization is enigmatic compared to general Archean lode gold deposits based on the fact that it is characterized by an exotic mineralogy containing elements such as As, Hg, Sb, Ba, V and Mo. The genetic concepts range from syngenetic to epigenetic types of mineralization. This reconnaissance study was designed to examine the relationship of Hg-As minerals with respect to fluid inclusions in the Williams mine (formerly known as the Page Williams mine) covering the A and C ore zones.

  18. Source attribution and process analysis for atmospheric mercury in East China simulated by CMAQ-Hg

    Science.gov (United States)

    Zhu, J.; Wang, T.; Bieser, J.; Matthias, V.

    2015-04-01

    The contribution from different emission sources and atmospheric processes to gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM), particulate bound mercury (PBM) and mercury deposition in East China were quantified using the Community Multi-scale Air Quality (CMAQ-Hg) modeling system run with nested grid resolution of 27 km. Natural source (NAT) and six categories of anthropogenic mercury sources (ANTH) including cement production (CEM), domestic life (DOM), industrial boilers (IND), metal production (MET), coal-fired power plants (PP) and traffic (TRA) were considered for source apportionment. NAT was responsible for 36.6% of annual averaged GEM concentration which was regard as the most important source for GEM in spite of obvious seasonal variation. Among ANTH, the influence of MET and PP on GEM were most evident especially in winter. ANTH dominated the variations of GOM and PBM concentration with a contribution of 86.7 and 79.1% respectively. Among ANTH, IND was the largest contributor for GOM (57.5%) and PBM (34.4%) so that most mercury deposition came from IND. The effect of mercury emitted from out of China was indicated by > 30% contribution to GEM concentration and wet deposition. The contribution from nine processes consisting of emissions (EMIS), gas-phase chemical production/loss (CHEM), horizontal advection (HADV), vertical advection (ZADV), horizontal advection (HDIF), vertical diffusion (VDIF), dry deposition (DDEP), cloud processes (CLDS) and aerosol processes (AERO) were calculated for processes analysis with their comparison in urban and non-urban regions of Yangtze River Delta (YRD). EMIS and VDIF affected surface GEM and PBM concentration most and tended to compensate each other all the time in both urban and non-urban areas. However, DDEP was the most important removal process for GOM with 7.3 and 2.9 ng m-3 reduced in the surface of urban and non-urban areas respectively in a whole day. Diurnal profile variation of processes

  19. Source attribution and process analysis for atmospheric mercury in eastern China simulated by CMAQ-Hg

    Science.gov (United States)

    Zhu, J.; Wang, T.; Bieser, J.; Matthias, V.

    2015-08-01

    The contribution from different emission sources and atmospheric processes to gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM), particulate bound mercury (PBM) and mercury deposition in eastern China were quantified using the Community Multi-scale Air Quality (CMAQ-Hg) modeling system run with a nested domain. Natural sources (NAT) and six categories of anthropogenic mercury sources (ANTH) including cement production (CEM), domestic life (DOM), industrial boilers (IND), metal production (MET), coal-fired power plants (PP) and traffic (TRA) were considered for source apportionment. NAT were responsible for 36.6 % of annual averaged GEM concentration, which was regarded as the most important source for GEM in spite of obvious seasonal variation. Among ANTH, the influence of MET and PP on GEM were most evident especially in winter. ANTH dominated the variations of GOM and PBM concentrations with contributions of 86.7 and 79.1 %, respectively. Among ANTH, IND were the largest contributor for GOM (57.5 %) and PBM (34.4 %) so that most mercury deposition came from IND. The effect of mercury emitted from out of China was indicated by a > 30 % contribution to GEM concentration and wet deposition. The contributions from nine processes - consisting of emissions (EMIS), gas-phase chemical production/loss (CHEM), horizontal advection (HADV), vertical advection (ZADV), horizontal advection (HDIF), vertical diffusion (VDIF), dry deposition (DDEP), cloud processes (CLDS) and aerosol processes (AERO) - were calculated for process analysis with their comparison in urban and non-urban regions of the Yangtze River delta (YRD). EMIS and VDIF affected surface GEM and PBM concentrations most and tended to compensate each other all the time in both urban and non-urban areas. However, DDEP was the most important removal process for GOM with 7.3 and 2.9 ng m-3 reduced in the surface of urban and non-urban areas, respectively, in 1 day. The diurnal profile variation of

  20. Source attribution and process analysis for atmospheric mercury in East China simulated by CMAQ-Hg

    Directory of Open Access Journals (Sweden)

    J. Zhu

    2015-04-01

    Full Text Available The contribution from different emission sources and atmospheric processes to gaseous elemental mercury (GEM, gaseous oxidized mercury (GOM, particulate bound mercury (PBM and mercury deposition in East China were quantified using the Community Multi-scale Air Quality (CMAQ-Hg modeling system run with nested grid resolution of 27 km. Natural source (NAT and six categories of anthropogenic mercury sources (ANTH including cement production (CEM, domestic life (DOM, industrial boilers (IND, metal production (MET, coal-fired power plants (PP and traffic (TRA were considered for source apportionment. NAT was responsible for 36.6% of annual averaged GEM concentration which was regard as the most important source for GEM in spite of obvious seasonal variation. Among ANTH, the influence of MET and PP on GEM were most evident especially in winter. ANTH dominated the variations of GOM and PBM concentration with a contribution of 86.7 and 79.1% respectively. Among ANTH, IND was the largest contributor for GOM (57.5% and PBM (34.4% so that most mercury deposition came from IND. The effect of mercury emitted from out of China was indicated by > 30% contribution to GEM concentration and wet deposition. The contribution from nine processes consisting of emissions (EMIS, gas-phase chemical production/loss (CHEM, horizontal advection (HADV, vertical advection (ZADV, horizontal advection (HDIF, vertical diffusion (VDIF, dry deposition (DDEP, cloud processes (CLDS and aerosol processes (AERO were calculated for processes analysis with their comparison in urban and non-urban regions of Yangtze River Delta (YRD. EMIS and VDIF affected surface GEM and PBM concentration most and tended to compensate each other all the time in both urban and non-urban areas. However, DDEP was the most important removal process for GOM with 7.3 and 2.9 ng m−3 reduced in the surface of urban and non-urban areas respectively in a whole day. Diurnal profile variation of processes

  1. Wetting of real surfaces

    CERN Document Server

    Bormashenko, Edward Yu

    2013-01-01

    The problem of wetting and drop dynamics on various surfaces is very interesting from both the scientificas well as thepractical viewpoint, and subject of intense research.The results are scattered across papers in journals, sothis workwill meet the need for a unifying, comprehensive work.

  2. Wet Macular Degeneration

    Science.gov (United States)

    ... macular degeneration Overview By Mayo Clinic Staff Wet macular degeneration is a chronic eye disease that causes blurred vision or a blind spot in your visual field. It's generally caused by abnormal blood vessels that leak fluid or blood into ... macular degeneration is one of two types of age-related ...

  3. Effects of urbanization on mercury deposition and accumulation in New England.

    Science.gov (United States)

    Chalmers, Ann T; Krabbenhoft, David P; Van Metre, Peter C; Nilles, Mark A

    2014-09-01

    We compare total mercury (HgT) loading and methylmercury (MeHg) accumulation in streams and lakes from an urbanized area (Boston, Massachusetts) to rural regions of southern New Hampshire and Maine. The maximum HgT loading, as indicated by HgT atmospheric deposition, HgT emissions, and sediment HgT concentrations, did not coincide with maximum MeHg concentrations in fish. Urbanized ecosystems were areas of high HgT loading but had low MeHg concentrations in fish. Controls on MeHg production and accumulation appeared to be related primarily to HgT loading in undeveloped areas, while ecosystem sensitivity to MeHg formation appeared to be more important in regulating accumulation of MeHg in the urban area.

  4. Hg transfer from contaminated soils to plants and animals

    NARCIS (Netherlands)

    Rodrigues, S.M.; Henriques, B.; Reis, A.T.; Duarte, A.C.; Pereira, E.; Romkens, P.F.A.M.

    2012-01-01

    Understanding the transfer of mercury (Hg) from soil to crops is crucial due to Hg toxicity and Hg occurrence in terrestrial systems. Previous research has shown that available Hg in soils contributes to plant Hg levels. Plant Hg concentrations are related to soil conditions and plant characteristic

  5. Hg concentrations in fish from coastal waters of California and Western North America

    Science.gov (United States)

    Davis, Jay; Ross, John; Bezalel, Shira; Sim, Lawrence; Bonnema, Autumn; Ichikawa, Gary; Heim, Wes; Schiff, Kenneth C; Eagles-Smith, Collin A.; Ackerman, Josh

    2016-01-01

    The State of California conducted an extensive and systematic survey of mercury (Hg) in fish from the California coast in 2009 and 2010. The California survey sampled 3483 fish representing 46 species at 68 locations, and demonstrated that methylHg in fish presents a widespread exposure risk to fish consumers. Most of the locations sampled (37 of 68) had a species with an average concentration above 0.3 μg/g wet weight (ww), and 10 locations an average above 1.0 μg/g ww. The recent and robust dataset from California provided a basis for a broader examination of spatial and temporal patterns in fish Hg in coastal waters of Western North America. There is a striking lack of data in publicly accessible databases on Hg and other contaminants in coastal fish. An assessment of the raw data from these databases suggested the presence of relatively high concentrations along the California coast and in Puget Sound, and relatively low concentrations along the coasts of Alaska and Oregon, and the outer coast of Washington. The dataset suggests that Hg concentrations of public health concern can be observed at any location on the coast of Western North America where long-lived predator species are sampled. Output from a linear mixed-effects model resembled the spatial pattern observed for the raw data and suggested, based on the limited dataset, a lack of trend in fish Hg over the nearly 30-year period covered by the dataset. Expanded and continued monitoring, accompanied by rigorous data management procedures, would be of great value in characterizing methylHg exposure, and tracking changes in contamination of coastal fish in response to possible increases in atmospheric Hg emissions in Asia, climate change, and terrestrial Hg control efforts in coastal watersheds.

  6. Organ-specific accumulation, transportation, and elimination of methylmercury and inorganic mercury in a low Hg accumulating fish.

    Science.gov (United States)

    Peng, Xiaoyan; Liu, Fengjie; Wang, Wen-Xiong

    2016-08-01

    Low mercury (Hg) concentrations down to several nanograms Hg per gram of wet tissue are documented in certain fish species such as herbivorous fish, and the underlying mechanisms remain speculative. In the present study, bioaccumulation and depuration patterns of inorganic Hg(II) and methylmercury (MeHg) in a herbivorous rabbitfish Siganus canaliculatus were investigated at organ and subcellular levels following waterborne or dietary exposures. The results showed that the efflux rate constants of Hg(II) and MeHg were 0.104 d(-1) and 0.024 d(-1) , respectively, and are probably the highest rate constants recorded in fish thus far. The dietary MeHg assimilation efficiency (68%) was much lower than those in other fish species (∼90%). The predominant distribution of MeHg in fish muscle was attributable to negligible elimination of MeHg from muscle (rabbitfish was partly explained by its unique biokinetics. Environ Toxicol Chem 2016;35:2074-2083. © 2016 SETAC.

  7. Synthesis and characterization of HgI2 nanoparticles for films nucleation

    Science.gov (United States)

    Barthaburu, María Pérez; Galain, Isabel; Mombrú, Maia; Aguiar, Ivana; Olivera, Alvaro; Pereira, Heinkel Bentos; Fornaro, Laura

    2017-01-01

    With the aim of controlling the first steps in HgI2 film growth onto amorphous substrates, we employed HgI2 nanoparticles for nucleation. Hg(NO3)2 and NaI were used for obtaining HgI2 in water with and without citric or oxalic acid as capping agents. These samples were then subjected to a hydrothermal treatment at a constant temperature of 120 ºC during 2 h. All samples were washed, centrifuged and dried. This method presents a facile route for obtaining HgI2 nanoparticles and is easily scalable. HgI2 tetragonal phase was confirmed by powder X-ray diffraction. Nanoparticles were characterized in their size and morphology by transmission electron microscopy and the capping agent presence was studied by infrared spectroscopy. HgI2 nanoparticles synthesized in octadecene, previously reported, as well as nanoparticles obtained in the present work, were used for nucleation onto amorphous substrates. They were deposited onto floating silica glass by spin coating and the morphology of the layer was studied by atomic force microscopy. The results we obtained are the first involving HgI2 nucleation by spin coating, and are very promising for improving the film growth orientation and therefore the current applications of this material, as well as for opening new ones.

  8. Salt-marsh plants as potential sources of Hg0 into the atmosphere

    Science.gov (United States)

    Canário, João; Poissant, Laurier; Pilote, Martin; Caetano, Miguel; Hintelmann, Holger; O'Driscoll, Nelson J.

    2017-03-01

    To assess the role of salt-marsh plants on the vegetation-atmospheric Hg0 fluxes, three salt marsh plant species, Halimione portulacoides, Sarcocornia fruticosa and Spartina maritima were selected from a moderately contaminated site in the Tagus estuary during May 2012. Total mercury in stems and leaves for each plant as well as total gaseous mercury and vegetation-air Hg0 fluxes were measured over two continuous days. Mercury fluxes were estimated with a dynamic flux Tedlar® bag coupled to a high-resolution automated mercury analyzer (Tekran 2537A). Other environmental parameters such as air temperature, relative humidity and net solar radiation were also measured aside. H. portulacoides showed the highest total mercury concentrations in stems and leaves and the highest average vegetation-air Hg0 flux (0.48 ± 0.40 ng Hg m-2 h-1). The continuous measurements converged to a daily pattern for all plants, with enhanced fluxes during daylight and lower flux during the night. It is noteworthy that throughout the measurements a negative flux (air-vegetation) was never observed, suggesting the absence of net Hg0 deposition. Based on the above fluxes and the total area occupied by each species we have estimated the total amount of Hg0 emitted from this salt-marsh plants. A daily emission of 1.19 mg Hg d-1 was predicted for the Alcochete marsh and 175 mg Hg d-1 for the entire salt marsh area of the Tagus estuary.

  9. Microbial Oxidation of Hg(0) - Its Effect on Hg Stable Isotope Fractionation and Methylmercury Production

    Energy Technology Data Exchange (ETDEWEB)

    Yee, Nathan [Rutgers Univ., New Brunswick, NJ (United States); Barkay, Tamar [Rutgers Univ., New Brunswick, NJ (United States); Reinfelder, John [Rutgers Univ., New Brunswick, NJ (United States)

    2016-06-28

    Mercury (Hg) associated with mixed waste generated by nuclear weapons manufacturing has contaminated vast areas of the Oak Ridge Reservation (ORR). Neurotoxic methylmercury (MeHg) has been formed from the inorganic Hg wastes discharged into headwaters of East Fork Poplar Creek (EFPC). Thus, understanding the processes and mechanisms that lead to Hg methylation along the flow path of EFPC is critical to predicting the impacts of the contamination and the design of remedial action at the ORR. In part I of our project, we investigated Hg(0) oxidation and methylation by anaerobic bacteria. We discovered that the anaerobic bacterium Desulfovibrio desulfuricans ND132 can oxidize elemental mercury [Hg(0)]. When provided with dissolved elemental mercury, D. desulfuricans ND132 converts Hg(0) to Hg(II) and neurotoxic methylmercury [MeHg]. We also demonstrated that diverse species of subsurface bacteria oxidizes dissolved elemental mercury under anoxic conditions. The obligate anaerobic bacterium Geothrix fermentans H5, and the facultative anaerobic bacteria Shewanella oneidensis MR-1 and Cupriavidus metallidurans AE104 can oxidize Hg(0) to Hg(II) under anaerobic conditions. In part II of our project, we established anaerobic enrichment cultures and obtained new bacterial strains from the DOE Oak Ridge site. We isolated three new bacterial strains from subsurface sediments collected from Oak Ridge. These isolates are Bradyrhizobium sp. strain FRC01, Clostridium sp. strain FGH, and a novel Negativicutes strain RU4. Strain RU4 is a completely new genus and species of bacteria. We also demonstrated that syntrophic interactions between fermentative bacteria and sulfate-reducing bacteria in Oak Ridge saprolite mediate iron reduction via multiple mechanisms. Finally, we tested the impact of Hg on denitrification in nitrate reducing enrichment cultures derived from subsurface sediments from the Oak Ridge site, where nitrate is a major contaminant. We showed that there is an inverse

  10. Microbial Oxidation of Hg(0) - Its Effect on Hg Stable Isotope Fractionation and Methylmercury Production

    Energy Technology Data Exchange (ETDEWEB)

    Yee, Nathan [Rutgers Univ., New Brunswick, NJ (United States); Barkay, Tamar [Rutgers Univ., New Brunswick, NJ (United States); Reinfelder, John [Rutgers Univ., New Brunswick, NJ (United States)

    2016-06-28

    Mercury (Hg) associated with mixed waste generated by nuclear weapons manufacturing has contaminated vast areas of the Oak Ridge Reservation (ORR). Neurotoxic methylmercury (MeHg) has been formed from the inorganic Hg wastes discharged into headwaters of East Fork Poplar Creek (EFPC). Thus, understanding the processes and mechanisms that lead to Hg methylation along the flow path of EFPC is critical to predicting the impacts of the contamination and the design of remedial action at the ORR. In part I of our project, we investigated Hg(0) oxidation and methylation by anaerobic bacteria. We discovered that the anaerobic bacterium Desulfovibrio desulfuricans ND132 can oxidize elemental mercury [Hg(0)]. When provided with dissolved elemental mercury, D. desulfuricans ND132 converts Hg(0) to Hg(II) and neurotoxic methylmercury [MeHg]. We also demonstrated that diverse species of subsurface bacteria oxidizes dissolved elemental mercury under anoxic conditions. The obligate anaerobic bacterium Geothrix fermentans H5, and the facultative anaerobic bacteria Shewanella oneidensis MR-1 and Cupriavidus metallidurans AE104 can oxidize Hg(0) to Hg(II) under anaerobic conditions. In part II of our project, we established anaerobic enrichment cultures and obtained new bacterial strains from the DOE Oak Ridge site. We isolated three new bacterial strains from subsurface sediments collected from Oak Ridge. These isolates are Bradyrhizobium sp. strain FRC01, Clostridium sp. strain FGH, and a novel Negativicutes strain RU4. Strain RU4 is a completely new genus and species of bacteria. We also demonstrated that syntrophic interactions between fermentative bacteria and sulfate-reducing bacteria in Oak Ridge saprolite mediate iron reduction via multiple mechanisms. Finally, we tested the impact of Hg on denitrification in nitrate reducing enrichment cultures derived from subsurface sediments from the Oak Ridge site, where nitrate is a major contaminant. We showed that there is an inverse

  11. [HG-AFS determination of selenium in Moringa oleifera].

    Science.gov (United States)

    Huang, Guo-qing; Xiao, Zi-jun

    2007-02-01

    The Se content in Moringa oleifera was studied by hydride generation atom fluorescence spectrometry (HG-AFS) with wet digestion. The effects of the way of digestion, the work condition of apparatus, the reaction medium and acidity, and the reducing agent and masking agent on the determination of Se were investigated. And the operating condition of apparatus was optimized. The results showed that the detection limit of Se in this method was 0.42 ng x mL(-1) in the linear ranger of 0-120 ng x mL(-1), the relative standard deviation was 3.53% (n = 11), and the recovery of the method was 95.2%-104.6%. It was showed that the method was very sensitive, simple, rapid and accurate.

  12. WET SOLIDS FLOW ENHANCEMENT

    Energy Technology Data Exchange (ETDEWEB)

    Unknown

    2001-03-25

    The yield locus, tensile strength and fracture mechanisms of wet granular materials were studied. The yield locus of a wet material was shifted to the left of that of the dry specimen by a constant value equal to the compressive isostatic stress due to pendular bridges. for materials with straight yield loci, the shift was computed from the uniaxial tensile strength, either measured in a tensile strength tester or calculated from the correlation, and the angle of internal friction of the material. The predicted shift in the yield loci due to different moisture contents compare well with the measured shift in the yield loci of glass beads, crushed limestone, super D catalyst and Leslie coal. Measurement of the void fraction during the shear testing was critical to obtain the correct tensile strength theoretically or experimentally.

  13. Atmospheric deposition to forests in the eastern USA

    Science.gov (United States)

    Risch, Martin R.; DeWild, John F.; Gay, David A.; Zhang, Leiming; Boyer, Elizabeth W.; Krabbenhoft, David P.

    2017-01-01

    Atmospheric mercury (Hg) deposition to forests is important because half of the land cover in the eastern USA is forest. Mercury was measured in autumn litterfall and weekly precipitation samples at a total of 27 National Atmospheric Deposition Program (NADP) monitoring sites in deciduous and mixed deciduous-coniferous forests in 16 states in the eastern USA during 2007–2014. These simultaneous, uniform, repeated, annual measurements of forest Hg include the broadest area and longest time frame to date. The autumn litterfall-Hg concentrations and litterfall mass at the study sites each year were combined with annual precipitation-Hg data. Rates of litterfall-Hg deposition were higher than or equal to precipitation-Hg deposition rates in 70% of the annual data, which indicates a substantial contribution from litterfall to total atmospheric-Hg deposition. Annual litterfall-Hg deposition in this study had a median of 11.7 μg per square meter per year (μg/m2/yr) and ranged from 2.2 to 23.4 μg/m2/yr. It closely matched modeled dry-Hg deposition, based on land cover at selected NADP Hg-monitoring sites. Mean annual atmospheric-Hg deposition at forest study sites exhibited a spatial pattern partly explained by statistical differences among five forest-cover types and related to the mapped density of Hg emissions. Forest canopies apparently recorded changes in atmospheric-Hg concentrations over time because litterfall-Hg concentrations decreased year to year and litterfall-Hg concentrations were significantly higher in 2007–2009 than in 2012–2014. These findings reinforce reported decreases in Hg emissions and atmospheric elemental-Hg concentrations during this same time period. Methylmercury (MeHg) was detected in all litterfall samples at all sites, compared with MeHg detections in less than half the precipitation samples at selected sites during the study. These results indicate MeHg in litterfall is a pathway into the terrestrial food web where it can

  14. Writing on wet paper

    Science.gov (United States)

    Fridrich, Jessica; Goljan, Miroslav; Lisonek, Petr; Soukal, David

    2005-03-01

    In this paper, we show that the communication channel known as writing in memory with defective cells is a relevant information-theoretical model for a specific case of passive warden steganography when the sender embeds a secret message into a subset C of the cover object X without sharing the selection channel C with the recipient. The set C could be arbitrary, determined by the sender from the cover object using a deterministic, pseudo-random, or a truly random process. We call this steganography "writing on wet paper" and realize it using low-density random linear codes with the encoding step based on the LT process. The importance of writing on wet paper for covert communication is discussed within the context of adaptive steganography and perturbed quantization steganography. Heuristic arguments supported by tests using blind steganalysis indicate that the wet paper steganography provides improved steganographic security for embedding in JPEG images and is less vulnerable to attacks when compared to existing methods with shared selection channels.

  15. Growth, properties and applications of HgCdTe

    Science.gov (United States)

    Schmit, J. L.

    1983-12-01

    This paper provides primarily a review of the methods used to grow HgCdTe with a summary of some of its basic properties and applications. Methods of crystal growth fall generally into three classes: growth from the melt, from solution and from the vapor phase. All three methods have been and are being used to grow HgCdTe. The high vapor pressure of HgCdTe at the melting point, combined with a large segregation coefficient, have effectively limited the use of Czochralski or zone melting techniques, but two melt growth techniques have survived: (1) a variation of Bridgman growth called quench-anneal wherein a dendritic crystal is formed by quenching the melt and is homogenized by solid state recrystallization below the melting point, (2) a variation of freezing from a large volume called slush-growth wherein a melt is held in a temperature gradient for several weeks while a crystal grows. Growth from solution has taken the form of liquid phase epitaxy (LPE) on CdTe with the LPE systems including growth from Hg-rich, HgTe-rich and Te-rich solutions and using tipping, vertical dipping, vertical sliding and horizontal sliding. Vapor phase growth is very promising but is not yet in production. Techniques include growth by isothermal close spaced epitaxy in which HgTe is transported isothermally by chemical potential onto CdTe, molecular beam epitaxy (MBE) in which elements are evaporated in a high vacuum, and metal organic chemical vapor deposition (MOCVD) in which some of the metal atoms are carried to the substrate bound to organic radicals before being freed by pyrolysis. In all these methods, control of Hg pressure is a major concern. The fundamental properties discussed briefly are those of prime interest to detector manufacturers: energy gap ( Eg), intrinsic carrier concentration ( ni), and electrical activity of dopants. A reasonable fit to the Eg data from ˜ 20 papers is given by Eg = -0.302+1.93x+5.35×10 -4T(1-2x)-0.810x 2+0.832x 3. This gap, combined with k

  16. Fabrication and morphology of (Hg,Re)-1212 thin films on LaAlO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Su, J.H.; Sastry, P.V.P.S.S.; Schwartz, J

    2003-04-15

    Superconducting (Hg,Re)Ba{sub 2}CaCu{sub 2}O{sub y} ((Hg,Re)-1212) thin films have been prepared on single crystal substrates of LaAlO{sub 3} by reacting laser deposited ReBaCaCuO precursor films with CaHgO{sub 2} in sealed quartz tubes. The effects of the deposition parameters such as laser fluence and substrate temperature, on surface morphology and microstructure were examined by atomic force microscopy (AFM) and scanning electron microscopy (SEM). AFM observations revealed that a granular structure was seen in the precursor films deposited at lower energy (less than 200 mJ) and disappeared at higher energy (250 mJ). SEM investigation on final reacted films showed that the precursor films deposited at 250 deg. C resulted in a well-connected and uniformly dense microstructure, whereas the films deposited at lower or higher temperatures were porous and non-uniform.

  17. Letting Wet Spots be Wet: Restoring Natural Bioreactors in the Dissected Glacial Landscape

    Science.gov (United States)

    Schilling, Keith E.; McLellan, Eileen; Bettis, E. Arthur

    2013-12-01

    In this paper, we argue that there is tremendous potential for nitrate-N reductions to occur throughout the Corn Belt region of the USA if we simply let naturally occurring wet spots on the landscape be wet. Geologic and hydrologic data gathered in the Walnut Creek watershed located in south-central Iowa provides compelling evidence that substantial nutrient-processing capacity exists in this dissected glacial landscape. Self-similarity of stratigraphy, sedimentology and hydrology observed at all spatial scales in the watershed suggests that Holocene alluvial fill deposits provide a natural bioreactor for denitrification of upland groundwater nitrate-N; the occurrence of such deposits can be mapped to identify potential nitrogen sinks across the landscape. This approach to identifying potential nitrogen sinks is geology focused and extends potential locations for nutrient processing upstream into the headwater catchments of individual fields.

  18. Barrier formation at graded HgTe/CdTe heterojunctions

    Science.gov (United States)

    Goren, D.; Asa, G.; Nemirovsky, Y.

    1996-11-01

    Numerical calculations of graded HgTe/CdTe heterojunction (HJ) band diagrams at equilibrium are presented and discussed. The calculations are performed in the entire compositional range (0HJs are examined as a function of the graded region width and the graded region doping profiles. The graded region width and doping profiles were found to be the two main factors that determine whether barriers are formed as well as their shape and magnitude. The calculated results indicate that epitaxial ohmic HgTe contacts to extrinsic CdTe are possible, provided that the graded region is wider than one micron, and that it has the same doping type as the doping of the substrate with equal or higher absolute value. Further numerical calculations take into consideration the possible existence of distributed interface charges in the graded region of the HJ. It is shown that by assuming a classical transport over the potential barrier, the effective graded interface charge can be determined from the zero bias differential resistance of the HJ. Experimental transport measurements of metalorganic chemical vapor deposition (MOCVD) grown HgTe/p-CdTe graded HJs show a varying degree of rectification, indicating variations in the graded interface charge distributions which result from different MOCVD growth conditions.

  19. MBE Growth and Transfer of HgCdTe Epitaxial Films from InSb Substrates

    Science.gov (United States)

    de Lyon, T. J.; Rajavel, R. D.; Nosho, B. Z.; Terterian, S.; Beliciu, M. L.; Patterson, P. R.; Chang, D. T.; Boag-O'Brien, M. F.; Holden, B. T.; Jacobs, R. N.; Benson, J. D.

    2010-07-01

    An investigation of the heteroepitaxial growth of HgCdTe films onto InSb(211)B substrates is reported. High-quality HgCdTe(211)B single-crystal films have been successfully deposited onto InSb(211)B substrates and have been characterized with x-ray diffraction rocking curve analysis, etch pit density analysis, and surface void defect mapping. X-ray rocking curve (422) reflection full-width at half-maximum of 60 arcsec has been obtained for 7- μm-thick x = 0.22 HgCdTe epitaxial films, and etch pit densities of 3 × 106 cm-2 to 3 × 107 cm-2 have been observed. A significant reduction in HgCdTe void defect densities to 100 cm-2 to 200 cm-2 has been observed on InSb, including a complete absence of large “void cluster” defects that are often observed for growth on CdZnTe. Wafer bow induced by the growth of HgCdTe on InSb is less than 1 μm for 2-inch-diameter substrates. Significant diffusion of In into HgCdTe is observed for HgCdTe/InSb wafers that are subjected to Hg anneals at 250°C to 300°C. A preliminary investigation of the transfer of HgCdTe films from InSb onto Si substrates has also been undertaken, using an adhesive wafer bonding approach evaluated with scanning acoustic microscopy. The infrared transmission characteristics of the bonding adhesive have been investigated with respect to postgrowth annealing procedures to establish the compatibility of the bonding approach with HgCdTe device processing and detector operation.

  20. Seasonal and diurnal variations of Hg° over New England

    Directory of Open Access Journals (Sweden)

    J. D. Hegarty

    2007-11-01

    Full Text Available Factors influencing diurnal to interannual variability in Hg° over New England were investigated using multi-year measurements conducted by the AIRMAP program at the Thompson Farm (TF coastal site, an inland elevated site at Pac Monadnock (PM, and one summer of measurements on Appledore Island (AI in the Gulf of Maine. Mixing ratios of Hg° at TF showed distinct seasonality with maxima in March and minima in October. In comparison, Hg° at AI tracked the trend at TF but with higher minima, while at PM the diurnal and annual cycles were dampened. In winter, Hg° was correlated most strongly with CO and NOy, indicative of anthropogenic emissions as their primary source. Our analysis indicates that Hg° had a regional background level of ~160 fmol/mol, a summertime dry deposition velocity of ~0.20 cm s−1, and a ~16 day lifetime in the coastal boundary layer. The influence of oceanic emissions on ambient Hg° levels was identified using the Hg°-CHBr3 correlation at both TF and AI. Moreover, the lower Hg° levels and steeper decreasing warm season trend at TF (0.5–0.6 fmol/mol d−1 compared to PM (0.2–0.3 fmol/mol d−1 likely reflected the impact of marine halogen chemistry. Large interannual variability in warm season Hg° levels in 2004 versus 2005/2006 may be due to the role of precipitation patterns in influencing surface evasion of Hg°. In contrast, changes in wintertime maximum levels of Hg° were small compared to drastic reductions in CO, CO2, NOy, and SO2 from 2004/2005 to 2006/2007. These trends could be explained by a homogeneous surface distribution of Hg° over the North American continent in winter and/or rapid removal of mercury released from anthropogenic sources. We caution that during warmer winters, the Hg°-CO slope possibly reflects the ratio of Hg° loss relative to changes in CO more than their emission ratio.

  1. Seasonal and diurnal variations of Hg° over New England

    Directory of Open Access Journals (Sweden)

    J. D. Hegarty

    2008-03-01

    Full Text Available Factors influencing diurnal to interannual variability in Hg° over New England were investigated using multi-year measurements conducted by AIRMAP at the Thompson Farm (TF coastal site, an inland elevated site at Pac Monadnock (PM, and two month measurements on Appledore Island (AI in the Gulf of Maine. Mixing ratios of Hg° at TF showed distinct seasonality with maxima in March and minima in October. Hg° at AI tracked the trend at TF but with higher minima, while at PM the diurnal and annual cycles were dampened. In winter, Hg° was correlated most strongly with CO and NOy, indicative of anthropogenic emissions as their primary source. Our analysis indicates that Hg° had a regional background level of ~160 fmol/mol in winter, a dry deposition velocity of ~0.20 cm s−1 with a ~16 day lifetime in the coastal boundary layer in summer. The influence of oceanic emissions on ambient Hg° levels was identified using the Hg°-CHBr3 correlation at both TF and AI. Moreover, the lower Hg° levels and steeper decreasing warm season trend at TF (0.5–0.6 fmol/mol d−1 compared to PM (0.2–0.3 fmol/mol d−1 likely reflected the impact of marine halogen chemistry. Large interannual variability in warm season Hg° levels in 2004 versus 2005/2006 may be due to the role of precipitation patterns in influencing surface evasion of Hg°. In contrast, changes in wintertime maximum levels of Hg° were small compared to drastic reductions in CO, CO2, NOy, and SO2 from 2004/2005 to 2006/2007. These trends could be explained by a homogeneous distribution of Hg° over North American in winter due to its long lifetime and/or rapid removal of reactive mercury from anthropogenic sources. We caution that during warmer winters, the Hg°-CO slope possibly reflects Hg° loss relative to changes in CO more than their emission ratio.

  2. Influencing factors on the emission of mercury from wet flue gas desulphurisation slurries

    Energy Technology Data Exchange (ETDEWEB)

    Heidel, Barna; Farr, Silvio; Brechtel, Kevin; Scheffknecht, Guenter [Stuttgart Univ. (DE). Inst. fuer Feuerungs- und Kraftwerkstechnik (IFK); Thorwarth, Harald [EnBW Kraftwerke AG, Stuttgart (Germany)

    2012-07-01

    In this study, the chemical reduction and reemission of absorbed HgCl{sub 2} from slurries of a lab-scale wet FGD system was investigated. The ambivalent effect of SO{sub 3}{sup 2-} concentration on Hg chemistry was revealed. Low concentrations of SO{sub 3}{sup 2-} below 0.1 mol/m{sup 3} increase stability of Hg{sup 2+} by formation of Hg{sup 2+} complexes with SO{sub 3}{sup 2-} ligands. At elevated concentrations of SO{sub 3}{sup 2-}, their potential as reducing agent surpasses their favourable complexing function, thus leading to increased formation and reemission of HgO. The effect of operational pH on complex stability depends on the concentration of the dominating ligand in the slurry. (orig.)

  3. Phoenix's Wet Chemistry Lab

    Science.gov (United States)

    2008-01-01

    This is an illustration of the analytical procedure of NASA's Phoenix Mars Lander's Wet Chemistry Lab (WCL) on board the Microscopy, Electrochemistry, and Conductivity Analyzer (MECA) instrument. By dissolving small amounts of soil in water, WCL can determine the pH, the abundance of minerals such as magnesium and sodium cations or chloride, bromide and sulfate anions, as well as the conductivity and redox potential. The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  4. Phoenix's Wet Chemistry Lab

    Science.gov (United States)

    2008-01-01

    This is an illustration of soil analysis on NASA's Phoenix Mars Lander's Wet Chemistry Lab (WCL) on board the Microscopy, Electrochemistry, and Conductivity Analyzer (MECA) instrument. By dissolving small amounts of soil in water, WCL will attempt to determine the pH, the abundance of minerals such as magnesium and sodium cations or chloride, bromide and sulfate anions, as well as the conductivity and redox potential. The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  5. Wetting in Color

    Science.gov (United States)

    Burgess, Ian Bruce

    Colorimetric litmus tests such as pH paper have enjoyed wide commercial success due to their inexpensive production and exceptional ease of use. However, expansion of colorimetry to new sensing paradigms is challenging because macroscopic color changes are seldom coupled to arbitrary differences in the physical/chemical properties of a system. In this thesis I present in detail the development of Wetting in Color Technology, focusing primarily on its application as an inexpensive and highly selective colorimetric indicator for organic liquids. The technology exploits chemically-encoded inverse-opal photonic crystals to control the infiltration of fluids to liquid-specific spatial patterns, projecting minute differences in liquids' wettability to macroscopically distinct, easy-to-visualize structural color patterns. It is shown experimentally and corroborated with theoretical modeling using percolation theory that the high selectivity of wetting, upon-which the sensitivity of the indicator relies, is caused by the highly symmetric structure of our large-area, defect-free SiO2 inverse-opals. The regular structure also produces a bright iridescent color, which disappears when infiltrated with liquid - naturally coupling the optical and fluidic responses. Surface modification protocols are developed, requiring only silanization and selective oxidation, to facilitate the deterministic design of an indicator that differentiates a broad range of liquids. The resulting tunable, built-in horizontal and vertical chemistry gradients allow the wettability threshold to be tailored to specific liquids across a continuous range, and make the readout rely only on countable color differences. As wetting is a generic fluidic phenomenon, Wetting in Color technology could be suitable for applications in authentication or identification of unknown liquids across a broad range of industries. However, the generic nature of the response also ensures chemical non-specificity. It is shown

  6. In situ compositional control of advanced HgCdTe-based IR detectors

    Science.gov (United States)

    Almeida, L. A.; Dinan, J. H.

    1999-05-01

    The application of a feedback control system for maintaining a desired compositional profile during Hg 1- xCd xTe epitaxy is reported. A spectroscopic ellipsometer monitored the optical properties of Hg 1- xCd xTe films during deposition by molecular beam epitaxy. A library of optical constants was established from in situ measurements of multiple layers of varying composition. The compositions were subsequently determined ex situ using Fourier transform infrared spectroscopy. This work represents an extension of the compositional range of this control system to measure the x-values of Hg 1- xCd xTe sensitive to long-, mid-, and short-wavelength infrared (LWIR, MWIR, and SWIR) radiation (0.16CdTe effusion cell. The application of this control system is demonstrated by measuring the compositional profile of a three layer Hg 1- xCd xTe structure suitable for use as an MWIR/SWIR detector.

  7. Engineering steps for optimizing high temperature LWIR HgCdTe photodiodes

    Science.gov (United States)

    Madejczyk, Pawel; Gawron, Waldemar; Martyniuk, Piotr; Keblowski, Artur; Pusz, Wioletta; Pawluczyk, Jaroslaw; Kopytko, Malgorzata; Rutkowski, Jaroslaw; Rogalski, Antoni; Piotrowski, Jozef

    2017-03-01

    The authors report on energy gap engineering solutions to improve the high-temperature performance of long-wave infrared (LWIR) HgCdTe photodiodes. Metalorganic chemical vapour deposition (MOCVD) technology with a wide range of composition and donor/acceptor doping and without ex-situ post grown annealing seems to be an excellent tool for HgCdTe heterostructure epitaxial growth. The heterojunction HgCdTe photovoltaic device based on epitaxial graded gap structures integrated with Auger-suppression is a magnificent solution for high operating temperature (HOT) infrared detectors. The thickness, composition and doping of HgCdTe heterostructure were optimized with respect to photoelectrical parameters like dark current, the responsivity and the response time. In this paper we focus on graded interface abruptness in the progressive optimization.

  8. Emission Spectra of Working Mixtures of a HgBr/HgCl Excimer Lamp

    Science.gov (United States)

    Malinin, A. N.; Guĭvan, N. N.; Shimon, L. L.

    2000-12-01

    A study of emission spectra of a gas-discharge plasma produced in a HgBr/HgCl excimer lamp, which is filled with multicomponent working mixtures at atmospheric pressure (HgBr2 and HgCl2 with additions of molecular nitrogen and xenon), are reported. A gas-discharge plasma was produced by high-frequency (pulses ˜100 ns long with a repetition rate of up to 2000 Hz) barrier and surface discharges, which took place simultaneously. Emission of HgBr* and HgCl* excimer molecules, the second positive system of molecular oxygen, and helium and xenon lines in the UV, visible, and IR spectral regions was observed. The strongest emission of HgBr* and HgCl* molecules (the emission intensities were in the ratio 10:1) was observed in the HgBr2: HgCl2: N2: He mixture. Regularities in spectral and integrated characteristics of gas-discharge plasma emission are discussed.

  9. HgTe-CdTe SUPERLATTICES

    OpenAIRE

    Smith, D; Mcgill, T.

    1984-01-01

    We report on a theoretical study of the electronic properties of HgTe-CdTe superlattices. The band gap as a function of layer thickness, effective masses normal to the layer plane and tunneling length are compared to the corresponding (Hg, Cd)Te alloys. We find that the superlattice possesses a number of properties that may make it superior to the corresponding alloy as an infrared material.

  10. Hg0 absorption in potassium persulfate solution

    Institute of Scientific and Technical Information of China (English)

    YE Qun-feng; WANG Cheng-yun; WANG Da-hui; SUN Guan; XU Xin-hua

    2006-01-01

    The aqueous phase oxidation of gaseous elemental mercury (Hg0) by potassium persulfate (KPS) catalyzed by Ag+was investigated using a glass bubble column reactor. Concentration of gaseous mercury and potassium persulfate were measured by cold vapor atom absorption (CVAA) and ion chromatograph (IC), respectively. The effects of pH value, concentration of potassium persulfate and silver nitrate (SN), temperature, Hg0 concentration in the reactor inlet and tertiary butanol (TBA), free radical scavenger, on the removal efficiency of Hg0 were studied. The results showed that the removal efficiency of Hg0 increased with increasing concentration of potassium persulfate and silver nitrate, while temperature and TBA were negatively effective. Furthermore, the removal efficiency of Hg0 was much better in neutral solution than in both acidic and alkaline solution. But the influence of pH was almost eliminated by adding AgNO3. High Hg0 concentration has positive effect. The possible reaction mechanism of gaseous mercury was also discussed.

  11. Wet steam wetness measurement in a 10 MW steam turbine

    Directory of Open Access Journals (Sweden)

    Kolovratník Michal

    2014-03-01

    Full Text Available The aim of this paper is to introduce a new design of the extinction probes developed for wet steam wetness measurement in steam turbines. This new generation of small sized extinction probes was developed at CTU in Prague. A data processing technique is presented together with yielded examples of the wetness distribution along the last blade of a 10MW steam turbine. The experimental measurement was done in cooperation with Doosan Škoda Power s.r.o.

  12. Wet steam wetness measurement in a 10 MW steam turbine

    OpenAIRE

    Kolovratník Michal; Bartoš Ondřej

    2014-01-01

    The aim of this paper is to introduce a new design of the extinction probes developed for wet steam wetness measurement in steam turbines. This new generation of small sized extinction probes was developed at CTU in Prague. A data processing technique is presented together with yielded examples of the wetness distribution along the last blade of a 10MW steam turbine. The experimental measurement was done in cooperation with Doosan Škoda Power s.r.o.

  13. Identification of contamination in a lake sediment core using Hg and Pb isotopic compositions, Lake Ballinger, Washington, USA

    Science.gov (United States)

    Gray, John E.; Pribil, Michael J.; Van Metre, Peter C.; Borrok, David M.; Thapalia, Anita

    2013-01-01

    Concentrations and isotopic compositions of Hg and Pb were measured in a sediment core collected from Lake Ballinger, near Seattle, Washington, USA. Lake Ballinger has been affected by input of metal contaminants emitted from the Tacoma smelter, which operated from 1887 to 1986 and was located about 53 km south of the lake. Concentrations and loadings of Hg and Pb in Lake Ballinger increased by as much as three orders of magnitude during the period of smelting as compared to the pre-smelting period. Concentrations and loadings of Hg and Pb then decreased by about 55% and 75%, respectively, after smelting ended. Isotopic compositions of Hg changed considerably during the period of smelting (δ202Hg = −2.29‰ to −0.38‰, mean −1.23‰, n = 9) compared to the pre-smelting period (δ202Hg = −2.91‰ to −2.50‰, mean −2.75‰, n = 4). Variations were also observed in 206Pb/207Pb and 208Pb/207Pb isotopic compositions during these periods. Data for Δ199Hg and Δ201Hg indicate mass independent fractionation (MIF) of Hg isotopes in Lake Ballinger sediment during the smelting and post-smelting period and suggest MIF in the ore smelted, during the smelting process, or chemical modification at some point in the past. Negative values for Δ199Hg and Δ201Hg for the pre-smelting period are similar to those previously reported for soil, peat, and lichen, likely suggesting some component of atmospheric Hg. Variations in the concentrations and isotopic compositions of Hg and Pb were useful in tracing contaminant sources and the understanding of the depositional history of sedimentation in Lake Ballinger.

  14. 46 CFR 53.05-1 - Safety valve requirements for steam boilers (modifies HG-400 and HG-401).

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Safety valve requirements for steam boilers (modifies HG... requirements for steam boilers (modifies HG-400 and HG-401). (a) The pressure relief valve requirements and the safety valve requirements for steam boilers must be as indicated in HG-400 and HG-401 of section IV...

  15. Investigation of Hg uptake and transport between paddy soil and rice seeds combining Hg isotopic composition and speciation

    Directory of Open Access Journals (Sweden)

    C. Feng

    2016-02-01

    Full Text Available Abstract Human consumption of rice constitutes a potential toxicological risk in mercury (Hg polluted areas such as Hg mining regions in China. It is recognized to be an important source of Hg for the local human diet considering the efficient bioaccumulation of methylmercury (MeHg in rice seed. To assess Hg sources and uptake pathways to the rice plants, Hg speciation and isotopic composition were investigated in rice seeds and their corresponding paddy soils from different locations within the Wanshan Hg mining area (Guizhou Province, China. A large variation of Hg speciation is observed in rice seeds and paddy soils irrespective of the sampling location. Mass dependent fractionation (MDF of Hg in rice seeds differs by up to ∼4.0 ‰ in δ202Hg values, while mass independent fractionation (MIF of Hg isotopes remains constant (Δ199Hg ∼ 0‰. Hg isotopic composition in rice seeds covaries with that of paddy soils but exhibits lighter isotopic signature (δ202Hg. Such isotopic offset is mainly attributed to plant uptake and translocation processes. Also, seeds containing higher MeHg (MeHg/total Hg > 50% have significantly heavier Hg isotopes suggesting that MeHg uptake and transport to the seed in such rice plants is facilitated compared to inorganic Hg.

  16. Long-term Hg pollution induced Hg tolerance in the terrestrial isopod Porcellio scaber (Isopoda, Crustacea).

    Science.gov (United States)

    Lapanje, A; Drobne, D; Nolde, N; Valant, J; Muscet, B; Leser, V; Rupnik, M

    2008-06-01

    The aim of our work was to assess the pollution-induced community tolerance (PICT) of isopod gut microbiota and pollution-induced isopod population tolerance (PIPT). Animals collected from a chronically Hg polluted and an unpolluted location were exposed for 14 days to 10microg Hg/g dry food under laboratory conditions. The lysosomal membrane stability, hepatopancreas epithelium thickness, feeding activity and animal bacterial gut microbiota composition were determined. The results confirm the hypothesis that the response to short-term Hg exposure differs for animals from the Hg polluted and the unpolluted field locations. The animals and their gut microbiota from the Hg polluted location were less affected by Hg in a short-term feeding experiment than those from the unpolluted environment. We discuss the pollution-induced population tolerance of isopods and their gut microbiota as a measure of effects of long-term environmental pollution. The ecological consequences of such phenomena are also discussed.

  17. Zuotai and HgS differ from HgCl2 and methyl mercury in Hg accumulation and toxicity in weanling and aged rats.

    Science.gov (United States)

    Zhang, Bin-Bin; Li, Wen-Kai; Hou, Wei-Yu; Luo, Ya; Shi, Jing-Zhen; Li, Cen; Wei, Li-Xin; Liu, Jie

    2017-09-15

    Mercury sulfides are used in Ayurvedic medicines, Tibetan medicines, and Chinese medicines for thousands of years and are still used today. Cinnabar (α-HgS) and metacinnabar (β-HgS) are different from mercury chloride (HgCl2) and methylmercury (MeHg) in their disposition and toxicity. Whether such scenario applies to weanling and aged animals is not known. To address this question, weanling (21d) and aged (450d) rats were orally given Zuotai (54% β-HgS, 30mg/kg), HgS (α-HgS, 30mg/kg), HgCl2 (34.6mg/kg), or MeHg (MeHgCl, 3.2mg/kg) for 7days. Accumulation of Hg in kidney and liver, and the toxicity-sensitive gene expressions were examined. Animal body weight gain was decreased by HgCl2 and to a lesser extent by MeHg, but unaltered after Zuotai and HgS. HgCl2 and MeHg produced dramatic tissue Hg accumulation, increased kidney (kim-1 and Ngal) and liver (Ho-1) injury-sensitive gene expressions, but such changes are absent or mild after Zuotai and HgS. Aged rats were more susceptible than weanling rats to Hg toxicity. To examine roles of transporters in Hg accumulation, transporter gene expressions were examined. The expression of renal uptake transporters Oat1, Oct2, and Oatp4c1 and hepatic Oatp2 was decreased, while the expression of renal efflux transporter Mrp2, Mrp4 and Mdr1b was increased following HgCl2 and MeHg, but unaffected by Zuotai and HgS. Thus, Zuotai and HgS differ from HgCl2 and MeHg in producing tissue Hg accumulation and toxicity, and aged rats are more susceptible than weanling rats. Transporter expression could be adaptive means to reduce tissue Hg burden. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. Controls on mercury and methylmercury deposition for two watersheds in Acadia National Park, Maine

    Science.gov (United States)

    Johnson, K.B.; Haines, T.A.; Kahl, J.S.; Norton, S.A.; Amirbahman, A.; Sheehan, K.D.

    2007-01-01

    Throughfall and bulk precipitation samples were collected for two watersheds at Acadia National Park, Maine, from 3 May to 16 November 2000, to determine which landscape factors affected mercury (Hg) deposition. One of these watersheds, Cadillac Brook, burned in 1947, providing a natural experimental design to study the effects of forest type on deposition to forested watersheds. Sites that face southwest received the highest Hg deposition, which may be due to the interception of cross-continental movement of contaminated air masses. Sites covered with softwood vegetation also received higher Hg deposition than other vegetation types because of the higher scavenging efficiency of the canopy structure. Methyl mercury (MeHg) deposition was not affected by these factors. Hg deposition, as bulk precipitation and throughfall was lower in Cadillac Brook watershed (burned) than in Hadlock Brook watershed (unburned) because of vegetation type and watershed aspect. Hg and MeHg inputs were weighted by season and vegetation type because these two factors had the most influence on deposition. Hg volatilization was not determined. The total Hg deposition via throughfall and bulk precipitation was 9.4 ??g/m2/year in Cadillac Brook watershed and 10.2 ??g/m2/year in Hadlock Brook watershed. The total MeHg deposition via throughfall and bulk precipitation was 0.05 ??g/m2/year in Cadillac Brook watershed and 0.10 ??g/m2/year in Hadlock Brook watershed. ?? Springer Science + Business Media B.V. 2006.

  19. Spatial-temporal dynamics and sources of total Hg in a hydroelectric reservoir in the Western Amazon, Brazil.

    Science.gov (United States)

    Pestana, I A; Bastos, W R; Almeida, M G; de Carvalho, D P; Rezende, C E; Souza, C M M

    2016-05-01

    Damming rivers to construct hydroelectric reservoirs results in a series of impacts on the biogeochemical Hg cycle. For example, modifying the hydrodynamics of a natural watercourse can result in the suspension and transport of Hg deposits in the water column, which represents an exposure risk for biota. The objective of this study was to evaluate the influences of seasonality on the dispersion of total Hg in the Hydroelectric Power Plant (HPP)-Samuel Reservoir (Porto Velho/Brazil). Sampling campaigns were performed during the three following hydrological periods characteristic of the region: low (Oct/2011), ebbing (May/2012), and high (Feb/2013) water. Sediment profiles, suspended particulate matter (SPM), and aquatic macrophytes (Eicchornia crassipes and Oryza spp.) were collected, and their Hg concentrations and isotopic and elemental C and N signatures were determined. The drainage basin significantly influenced the SPM compositions during all the periods, with a small autochthonous influence from the reservoir during the low water. The highest SPM Hg concentrations inside the reservoir were observed during the high water period, suggesting that the hydrodynamics of this environment favor the suspension of fine SPM, which has a higher Hg adsorption capacity. The Hg concentrations in the sediment profiles were ten times lower than those in the SPM, indicating that large particles with low Hg concentrations were deposited to form the bottom sediment. Hg concentrations were higher in aquatic macrophyte roots than in their leaves and appeared to contribute to the formation of SPM during the low water period. In this environment, Hg transport mainly occurs in SPM from the Jamari River drainage basin, which is the primary source of Hg in this environment.

  20. Local probing of Hg neighboorhood in HgBa$_{2}$CuO$_{4+\\delta}$

    CERN Document Server

    Correia, J G; Loureiro, S M; Toulemonde, P; Le Floc'h, S; Bordet, P; Capponi, J J; Gatt, R; Tröger, W; Ctortecka, B; Butz, T; Haas, H; Marques, J G; Soares, J C

    2000-01-01

    Electric field gradients (EFG) on mercury sites of the Hg1201 high-TC superconductors were measured with the perturbed angular correlation (PAC) technique. In Hg1201 samples where PAC detects higher oxygen content the EFGs have decreased to lower values indicating an elongation of the Hg-apical oxygen dumb-bell. On the same samples the asymmetry parameter of the EFG becomes non-zero below 100 K, showing that the charge distribution near the Hg-apical oxygen chain becomes non-axially symmetric at low temperature.

  1. Complexation of Hg with phytochelatins is important for plant Hg tolerance.

    Science.gov (United States)

    Carrasco-Gil, Sandra; Alvarez-Fernández, Ana; Sobrino-Plata, Juan; Millán, Rocío; Carpena-Ruiz, Ramón O; Leduc, Danika L; Andrews, Joy C; Abadía, Javier; Hernández, Luís E

    2011-05-01

    Three-week-old alfalfa (Medicago sativa), barley (Hordeum vulgare) and maize (Zea mays) were exposed for 7 d to 30 µm of mercury (HgCl(2) ) to characterize the Hg speciation in root, with no symptoms of being poisoned. The largest pool (99%) was associated with the particulate fraction, whereas the soluble fraction (SF) accounted for a minor proportion (phytochelatins (PCs) in root SF, which was particularly varied in alfalfa (eight ligands and five stoichiometries), a species that also accumulated homophytochelatins. Spatial localization of Hg in alfalfa roots by microprobe synchrotron X-ray fluorescence spectroscopy showed that most of the Hg co-localized with sulphur in the vascular cylinder. Extended X-ray Absorption Fine Structure (EXAFS) fingerprint fitting revealed that Hg was bound in vivo to organic-S compounds, i.e. biomolecules containing cysteine. Albeit a minor proportion of total Hg, Hg-PCs complexes in the SF might be important for tolerance to Hg, as was found with Arabidopsis thaliana mutants cad2-1 (with low glutathione content) and cad1-3 (unable to synthesize PCs) in comparison with wild type plants. Interestingly, high-performance liquid chromatography-electrospray ionization-time of flight analysis showed that none of these mutants accumulated Hg-biothiol complexes.

  2. Wet solids flow enhancemant

    Energy Technology Data Exchange (ETDEWEB)

    Caram, H.S.; Foster, N.; Wildman, D.J. [USDOE Pittsburgh Energy Technology Center, PA (United States)

    1996-12-31

    WE used glass beads of different sizes as.a model system to study the flow enhancing properties of Octadecyltrichlorosilane (OTS). 0TS provides Si(CH{sub 2}){sub 17}CH{sub 3} groups that bind with the surface hydrox groups to make it hydrophobic. Experimental data showed, indeed, that surface hydrophobicity promotes the flow of wet granular materials. Mixtures of different percentage of silanized/unsilanized particles were prepared for tensile strength measurements. The tensile strength decreased as more silanized particles were added to the samples. The relationship between dimensionless tensile strength and void fraction followed the correlation found by Pierrat (1994). Contact angles were larger for the silanized particles, as compared with unsilanized ones.

  3. Wetting and Minimal Surfaces

    CERN Document Server

    Bachas, C; Wiese, K J; Bachas, Constantin; Doussal, Pierre Le; Wiese, Kay Joerg

    2006-01-01

    We study minimal surfaces which arise in wetting and capillarity phenomena. Using conformal coordinates, we reduce the problem to a set of coupled boundary equations for the contact line of the fluid surface, and then derive simple diagrammatic rules to calculate the non-linear corrections to the Joanny-de Gennes energy. We argue that perturbation theory is quasi-local, i.e. that all geometric length scales of the fluid container decouple from the short-wavelength deformations of the contact line. This is illustrated by a calculation of the linearized interaction between contact lines on two opposite parallel walls. We present a simple algorithm to compute the minimal surface and its energy based on these ideas. We also point out the intriguing singularities that arise in the Legendre transformation from the pure Dirichlet to the mixed Dirichlet-Neumann problem.

  4. To Wash Soluble Salt Deposits in the Flow Section of Steam Turbine with Wet Steam%利用湿蒸汽冲洗汽轮机通流部分可溶性盐垢

    Institute of Scientific and Technical Information of China (English)

    王长友; 党占东; 胡海

    2014-01-01

    Through analysis of the causes of high turbine flow resistance and high tem-perature of thrust bearing shoes, it was found that the main cause had been serious scaling in the flow section, which reduced the circulation area and in turn decreased the work ca-pacity of steam turbine preventing the unit from boosting to rated load. The causes of salt deposit in the flow section were also analyzed and studied and a flushing plan was drawn up, to reduce the resistance in the unit flow passages, lower the temperature of the thrust shoes and improve the safety and economy of the generating unit.%通过对汽轮机组通流部分阻力大、推力瓦温度高的原因进行分析,得出其主要原因为通流部分结垢严重,流通面积缩小,导致汽轮机做功能力下降,使机组无法带至额定负荷;并对通流部分结垢的原因进行分析、研究,作出冲洗方案,以求降低机组的通流部分阻力、推力瓦温度,提高机组的安全、经济性。

  5. Magnetic fields of HgMn stars

    CERN Document Server

    Hubrig, S; Ilyin, I; Korhonen, H; Schoeller, M; Savanov, I; Arlt, R; Castelli, F; Curto, G Lo; Briquet, M; Dall, T H

    2012-01-01

    The frequent presence of weak magnetic fields on the surface of spotted late-B stars with HgMn peculiarity in binary systems has been controversial during the two last decades. We re-analyse available spectropolarimetric material by applying the moment technique on spectral lines of inhomogeneously distributed elements separately. Furthermore, we present new determinations of the mean longitudinal magnetic field for the HgMn star HD65949 and the hotter analog of HgMn stars, the PGa star HD19400, using FORS2 installed at the VLT. We also give new measurements of the eclipsing system AR Aur with a primary star of HgMn peculiarity which were obtained with the SOFIN spectropolarimeter installed at the Nordic Optical Telescope. We downloaded from the ESO archive the publically available HARPS spectra for eight HgMn stars and one normal and one superficially normal B-type star obtained in 2010. The application of the moment technique to the HARPS and SOFIN spectra allowed us to study the presence of the longitudina...

  6. HgCdTe barrier infrared detectors

    Science.gov (United States)

    Kopytko, M.; Rogalski, A.

    2016-05-01

    In the last decade, new strategies to achieve high-operating temperature (HOT) detectors have been proposed, including barrier structures such as nBn devices, unipolar barrier photodiodes, and multistage (cascade) infrared detectors. The ability to tune the positions of the conduction and valence band edges independently in a broken-gap type-II superlattices is especially helpful in the design of unipolar barriers. This idea has been also implemented in HgCdTe ternary material system. However, the implementation of this detector structure in HgCdTe material system is not straightforward due to the existence of a valence band discontinuity (barrier) at the absorber-barrier interface. In this paper we present status of HgCdTe barrier detectors with emphasis on technological progress in fabrication of MOCVD-grown HgCdTe barrier detectors achieved recently at the Institute of Applied Physics, Military University of Technology. Their performance is comparable with state-of-the-art of HgCdTe photodiodes. From the perspective of device fabrication their important technological advantage results from less stringent surface passivation requirements and tolerance to threading dislocations.

  7. Atmospheric deposition of mercury in Atlantic Forest and ecological risk to soil fauna

    Science.gov (United States)

    Cristhy Buch, Andressa; Cabral Teixeira, Daniel; Fernandes Correia, Maria Elizabeth; Vieira Silva-Filho, Emmanoel

    2014-05-01

    The increasing levels of mercury (Hg) found in the atmosphere nowadays has a great contribution from anthropogenic sources and has been a great concern in the past two decades in industrialized countries. Brazil is the seventh country with the highest rate of mercury in the atmosphere. Certainly, the petroleum refineries have significant contribution, seen that 100 million m3 of crude oil are annually processed. These refineries contribute with low generation of solid waste; however, a large fraction of Hg can be emitted to the atmosphere. There are sixteen refineries in Brazil, three of them located in the state of Rio de Janeiro. The Hg is a toxic and hazardous trace element, naturally found in the earth crust. The major input of Hg to ecosystems is through atmospheric deposition (wet and dry), being transported in the atmosphere over large distances. The forest biomes are of great importance in the atmosphere/soil cycling of elemental Hg through foliar uptake and subsequent transfer to the soil through litterfall, which play an important role as Hg sink. The Atlantic Forest of Brazil is the greater contributor of fauna and flora biodiversity in the world and, according to recent studies, this biome has the highest concentrations of mercury in litter in the world, as well as in China, at Subtropical Forest. Ecotoxicological assessments can predict the potential ecological risk of Hg toxicity in the soil can lead to impact the soil fauna and indirectly other trophic levels of the food chain within one or more ecosystems. This study aims to determine mercury levels that represent risks to diversity and functioning of soil fauna in tropical forest soils. The study is conducted in two forest areas inserted into conservation units of Rio de Janeiro state. One area is located next to an important petroleum refinery in activity since fifty-two years ago, whereas the other one is located next to other refinery under construction (beginning activities in 2015), which will

  8. Wetting front instability in an initially wet unsaturated fracture

    Energy Technology Data Exchange (ETDEWEB)

    Nicholl, M.J.; Glass, R.J.; Nguyen, H.A.

    1992-12-31

    Experimental results exploring gravity-driven wetting front instability in a pre-wetted, rough-walled analog fracture are presented. Initial conditions considered include a uniform moisture field wetted to field capacity of the analog fracture and the structured moisture field created by unstable infiltration into an initially dry fracture. As in previous studies performed under dry initial conditions, instability was found to result both at the cessation of stable infiltration and at flux lower than the fracture capacity under gravitational driving force. Individual fingers were faster, narrower, longer, and more numerous than observed under dry initial conditions. Wetting fronts were found to follow existing wetted structure, providing a mechanism for rapid recharge and transport.

  9. Complexation of Hg with phytochelatins is important for plant Hg tolerance

    National Research Council Canada - National Science Library

    CARRASCO‐GIL, SANDRA; ÁLVAREZ‐FERNÁNDEZ, ANA; SOBRINO‐PLATA, JUAN; MILLÁN, ROCÍO; CARPENA‐RUIZ, RAMÓN O; LEDUC, DANIKA L; ANDREWS, JOY C; ABADÍA, JAVIER; HERNÁNDEZ, LUÍS E

    2011-01-01

    Three‐week‐old alfalfa ( Medicago sativa ), barley ( Hordeum vulgare ) and maize ( Zea mays ) were exposed for 7 d to 30  µ m of mercury (HgCl 2 ) to characterize the Hg speciation in root, with no symptoms of being poisoned...

  10. Temporal Characteristics of Emission of Working Mixtures of a HgBr/HgCl Excimer Lamp

    Science.gov (United States)

    Malinin, A. N.; Guĭvan, N. N.; Shimon, L. L.; Polyak, A. V.; Zubrilin, N. G.; Shchedrin, A. I.

    2001-12-01

    Results of a study of temporal characteristics of the emission of gas-discharge plasma of atmospheric pressure in multicomponent mixtures (mercury dibromide and dichloride with helium and additions of molecular nitrogen and xenon) of working media of HgBr/HgCl excimer lamps are presented. Gas-discharge plasma was produced and components of the working mixture were excited by high-frequency barrier and surface discharges occurring simultaneously. The repetition rate of the pumping pulse and its duration are 1000 Hz and ˜100 ns, respectively. It is found that the amplitude and the length of emission pulses and their trailing edge are modified in HgBr2: HgCl2: Xe: He and HgBr2: HgCl2: N2: He mixtures when xenon and molecular nitrogen are added, as compared to a HgBr2: HgCl2: He mixture. Regularities observed in temporal characteristics of gas-discharge plasma emission are discussed.

  11. Ground-state potential energy curves of LiHg, NaHg, and KHg revisited

    Science.gov (United States)

    Thiel, Linda; Hotop, Hartmut; Meyer, Wilfried

    2003-11-01

    We present the results of large-scale CCSD(T) calculations on the potential energy curves for the ground states of LiHg, NaHg, and KHg. In these calculations, the Hg20+ core is simulated by a pseudopotential which has been adjusted to reproduce experimental excitation and ionization energies of the Hg atom at the coupled-cluster level. Moreover, we apply a weighted multiproperty fitting procedure to determine reliable potentials for LiHg, NaHg, and KHg which reproduce the available experimental results. In the case of LiHg, this best-fit potential is based solely on experimental data and its agreement with our calculated potential supports our computational procedure. For NaHg and KHg the experimental data had to be complemented by theoretical results in order to fix a best-fit potential. Our potentials and those proposed previously are evaluated by comparing calculated scattering cross sections and vibrational energy levels with the available experimental data.

  12. ROE Total Nitrogen Deposition 1989-1991

    Data.gov (United States)

    U.S. Environmental Protection Agency — This dataset identifies the amount of wet, dry, and total deposition of nitrogen in kilograms per hectare from 1989 to 1991 at a set of point locations across the...

  13. ROE Total Sulfur Deposition 1989-1991

    Data.gov (United States)

    U.S. Environmental Protection Agency — This dataset identifies the amount of wet, dry, and total deposition of sulfur in kilograms per hectare from 1989 to 1991 at a set of point locations across the...

  14. ROE Total Nitrogen Deposition 2011-2013

    Data.gov (United States)

    U.S. Environmental Protection Agency — This dataset identifies the amount of wet, dry, and total deposition of nitrogen in kilograms per hectare from 2011 to 2013 at a set of point locations across the...

  15. ROE Total Sulfur Deposition 2011-2013

    Data.gov (United States)

    U.S. Environmental Protection Agency — This dataset identifies the amount of wet, dry, and total deposition of sulfur in kilograms per hectare from 2011 to 2013 at a set of point locations across the...

  16. Quasiparticle excitations in superdeformed {sup 192}Hg

    Energy Technology Data Exchange (ETDEWEB)

    Lauritsen, T.; Carpenter, M.P.; Janssens, R.V.F. [and others

    1995-08-01

    The nucleus {sup 192}Hg plays a pivotal role for superdeformation in the mass 190 region, since calculations of single-particle levels show large shell-gaps for the superdeformed (SD) shape at N = 112 and Z = 80. As a result, {sup 192}Hg is referred to as the doubly magic SD nucleus for the A = 190 region. In previous studies, only one superdeformed band was observed in this nucleus, and this fact was cited as indirect evidence that large shell gaps do indeed exist at the proposed particle numbers.

  17. Electric field gradients in Hg compounds

    DEFF Research Database (Denmark)

    Arcisauskaité, Vaida; Knecht, Stefan; Sauer, Stephan P. A.

    2012-01-01

    We examine the performance of Density Functional Theory (DFT) approaches based on the Zeroth-Order Regular Approximation (ZORA) Hamiltonian (with and without inclusion of spinorbit coupling) for predictions of electric ¿eld gradients (EFGs) at the heavy atom Hg nucleus. This is achieved by compar......We examine the performance of Density Functional Theory (DFT) approaches based on the Zeroth-Order Regular Approximation (ZORA) Hamiltonian (with and without inclusion of spinorbit coupling) for predictions of electric ¿eld gradients (EFGs) at the heavy atom Hg nucleus. This is achieved...

  18. Solution deposition of nanometer scale silver films as an alternative to vapor deposition for plasmonic excitation

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Derek S.; Sathish, R. Sai; Kostov, Yordan [Center for Advanced Sensor Technology and Department of Chemical and Biochemical Engineering, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250 (United States); Rao, Govind, E-mail: grao@umbc.ed [Center for Advanced Sensor Technology and Department of Chemical and Biochemical Engineering, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250 (United States)

    2010-05-03

    We report the attainment of surface plasmon-coupled emission (SPCE) from highly uniform thin silver films, solution-deposited on glass substrates by a wet chemistry approach. The surface morphology of these films was characterized by atomic force microscopy. The SPCE emission enhancements, polarization and angularity obtained from solution-deposited silver on BK7 glass were comparable to that achieved from conventional SPCE slides prepared via vapor deposition. This facile, wet chemistry procedure for the deposition of SPCE films provides an inexpensive, low maintenance alternative to vapor deposition for SPCE substrate preparation. This would allow the fluorescence observation technique to become more readily available for high sensitivity, low cost applications.

  19. Growing rice aerobically markedly decreases mercury accumulation by reducing both Hg bioavailability and the production of MeHg.

    Science.gov (United States)

    Wang, Xun; Ye, Zhihong; Li, Bing; Huang, Linan; Meng, Mei; Shi, Jianbo; Jiang, Guibin

    2014-01-01

    Rice consumption represents a major route of mercury (Hg) and methylmercury (MeHg) exposure for those living in certain areas of inland China. In this study we investigated the effects of water management on bioavailable Hg, MeHg, and sulfate-reducing bacteria (SRB, abundance and community composition) in rhizosphere soil, and total Hg (THg) and MeHg in rice plants grown under glasshouse and paddy field conditions. Aerobic conditions greatly decreased the amount of THg and MeHg taken up by rice plants and affected their distribution in different plant tissues. There were positive correlations between bioavailable Hg and THg in brown rice and roots and between numbers of SRB and MeHg in brown rice, roots, and rhizosphere soil. Furthermore, the community composition of SRB was dramatically influenced by the water management regimes. Our results demonstrate that the greatly reduced bioavailability of Hg and production of MeHg are due to decreased SRB numbers and proportion of Hg methylators in the rhizosphere under aerobic conditions. These are the main reasons for the reduced Hg and MeHg accumulation in aerobically grown rice. Water management is indicated as an effective measure that can be used to reduce Hg and MeHg uptake by rice plants from Hg-contaminated paddy fields.

  20. Effect of Mercury Deposition on Mercury Content and Distribution in Rye Grass

    Institute of Scientific and Technical Information of China (English)

    WEISHIQIANG; J.SOMMAR; 等

    1997-01-01

    A grass(Italian rye grass)experiment with complete desing of three factos(Hg,grass and exposure)and two levels(with and withou the factor tested)was carried out in Goeteborg,Sweden from May to September,1995,toward understanding the effect of mercury deposition on plant Hg content and its distribution.It has been found that besides the two general pathways of Hg absorption,i.e.root uptake and foliar absorption,mercury deposition can aslo signifcantly incease Hg content and total load in grass.Such effects seem to be confined only within the above-ground parts of grass plant.Estimate has been made to make clear of the contributions of different pathways to Hg Content and total Hg load in the upper part of grass.Results showed that the contribution of Hg deposition accounted for 27%-32%,of Hg content in the above-ground parts of grass plant without adding Hg to the soil.decreasing with the increase of soil and/or air Hg concentrations.The increment of Hg load in the upper part of grass plant caused by Hg deposition during an interval of two weeks varied between 0.01-0.07μg pt-1,contributing to 17%-48% of the total Hg load in grass plant exposed.

  1. 40 CFR 60.45Da - Standard for mercury (Hg).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Standard for mercury (Hg). 60.45Da... for mercury (Hg). (a) For each coal-fired electric utility steam generating unit other than an IGCC... gases that contain mercury (Hg) emissions in excess of each Hg emissions limit in paragraphs...

  2. MBE Growth and Characterization of Hg Based Compounds and Heterostructures

    Science.gov (United States)

    2002-06-03

    The molecular beam epitaxy ( MBE ) growth of Mercury Cadmium Telluride (Hg(1-x)Cd(x)Te) alloys and type III HgTe/Hg(1-x)Cd(x)Te heterostructures has...been discussed, including similarities and differences between the (0 0 1) and (1 1 2)Beta orientations. Furthermore, the MBE growth of HgTe-based

  3. Phenylselenolate Mercury Alkyl Compounds, PhSeHgMe and PhSeHgEt: Molecular Structures, Protolytic Hg-C Bond Cleavage and Phenylselenolate Exchange.

    Science.gov (United States)

    Yurkerwich, Kevin; Quinlivan, Patrick J; Rong, Yi; Parkin, Gerard

    2016-01-08

    The phenylselenolate mercury alkyl compounds, PhSeHgMe and PhSeHgEt, have been structurally characterized by X-ray diffraction, thereby demonstrating that both compounds are monomeric with approximately linear coordination geometries; the mercury centers do, nevertheless, exhibit secondary Hg•••Se intermolecular interactions that serve to increase the coordination number in the solid state. The ethyl derivative, PhSeHgEt, undergoes facile protolytic cleavage of the Hg-C bond to release ethane at room temperature, whereas PhSeHgMe exhibits little reactivity under similar conditions. Interestingly, the cleavage of the Hg-C bond of PhSeHgEt is also more facile than that of the thiolate analogue, PhSHgEt, which demonstrates that coordination by selenium promotes protolytic cleavage of the mercury-carbon bond. The phenylselenolate compounds PhSeHgR (R = Me, Et) also undergo degenerate exchange reactions with, for example, PhSHgR and RHgCl. In each case, the alkyl groups preserve coupling to the (199)Hg nuclei, thereby indicating that the exchange process involves metathesis of the Hg-SePh/Hg-X groups rather than metathesis of the Hg-R/Hg-R groups.

  4. The application of 199Hg NMR and 199mHg perturbed angular correlation (PAC) spectroscopy to define the biological chemistry of HgII

    DEFF Research Database (Denmark)

    Iranzo, Olga; Thulstrup, Peter Waaben; Ryu, Seung-baek;

    2007-01-01

    H values and at peptide/HgII ratios of 3:1 with an unusual trigonal thiolate coordination mode. The resulting HgII complexes are good water-soluble models for HgII binding to the protein MerR. We have carried out a parallel study using 199Hg NMR and 199mHg perturbed angular correlation (PAC) spectroscopy...... to characterize the distinct species that are generated under different pH conditions and peptide TRI L9C/HgII ratios. These studies prove for the first time the formation of [Hg{(TRI L9C)2-(TRI L9C H)}], a dithiolate-HgII complex in the hydrophobic interior of the three-stranded coiled coil (TRI L9C)3. 199Hg NMR...... and 199mHg PAC data demonstrate that this dithiolate-HgII complex is different from the dithiolate [Hg(TRI L9C)2], and that the presence of third -helix, containing a protonated cysteine, breaks the symmetry of the coordination environment present in the complex [Hg(TRI L9C)2]. As the pH is raised...

  5. Magnetic fields of HgMn stars

    DEFF Research Database (Denmark)

    Hubrig, S.; Gonzalez, J. F.; Ilyin, I.

    2012-01-01

    Context. The frequent presence of weak magnetic fields on the surface of spotted late-B stars with HgMn peculiarity in binary systems has been controversial during the two last decades. Recent studies of magnetic fields in these stars using the least-squares deconvolution (LSD) technique have fai...

  6. Hg contents in soils and olive-tree (Olea Europea, L.) leaves from an area affected by elemental mercury pollution (Jódar, SE Spain).

    Science.gov (United States)

    López-Berdonces, Miguel Angel; María Esbrí, José; Amorós, José Angel; Lorenzo, Saturnino; Fernández-Calderón, Sergio; Higueras, Pablo; Perez-de-los-Reyes, Caridad

    2014-05-01

    Data from soil and olive tree leaves around a decommissioned chlor-alkali plant are presented in this communication. The factory was active in the period 1977-1991, producing during these years a heavily pollution of Guadalquivir River and hydrargyrism in more than local 45 workers. It is located at 7 km South of Jódar, a locality with some 12,120 inhabitants. Mercury usage was general in this type of plants, but at present it is being replaced by other types of technologies, due to the risks of mercury usage in personal and environment. A soil geochemistry survey was carried out in the area, along with the analysis of olive-tree leaves (in the plots with this culture) from the same area. 73 soil samples were taken at two different depths (0-15 cm and 15-30 cm), together with 41 olive tree samples. Mercury content of geologic and biologic samples was determined by means of Atomic Absorption Spectrometry with Zeeman Effect, using a Lumex RA-915+ device with the RP-91C pyrolysis attachment. Air surveys were carried our using a RA-915M Lumex portable analytical device. Soil mercury contents were higher in topsoil than in the deeper soil samples, indicating that incorporation of mercury was due to dry and wet deposition of mercury vapors emitted from the plant. Average content in topsoil is 564.5 ng g-1. Hg contents in olive-tree leaves were in the range 46 - 453 ng g-1, with an average of 160.6 ng g-1. This level is slightly lower than tolerable level for agronomic crops established by Kabata-Pendias (2001) in 200 ng g-1. We have also compared soil and leaf contents for each sampling site, finding a positive and significant correlation (R=0.49), indicating that Hg contents in the leaves are linked to Hg contents in the soils. BAC (Bioaccumulation Absorption Coefficient, calculated as ratio between soil and leaf concentration) is 0.28 (consistent with world references, BAC = 0.7), considered "medium" in comparison with other mineral elements. Main conclusions of this

  7. First survey of atmospheric heavy metal deposition in Kosovo using moss biomonitoring.

    Science.gov (United States)

    Maxhuni, Albert; Lazo, Pranvera; Kane, Sonila; Qarri, Flora; Marku, Elda; Harmens, Harry

    2016-01-01

    Bryophytes act as bioindicators and bioaccumulators of metal deposition in the environment. The atmospheric deposition of Cd, Cr, Cu, Fe, Hg, Ni, Mn, Pb, and Zn in Kosovo was investigated by using carpet-forming moss species (Pseudocleropodium purum and Hypnum cupressiforme) as bioindicators. This research is part of the European moss survey coordinated by the ICP Vegetation, an International Cooperative Programme reporting on the effects of air pollution on vegetation to the UNECE Convention on Long-range Transboundary Air Pollution. Sampling was performed during the summer of 2011 at 25 sampling sites homogenously distributed over Kosovo. Unwashed, dried samples were digested by using wet digestion in Teflon tubes. The concentrations of metal elements were determined by atomic absorption spectrometry (AAS) equipped with flame and/or furnace systems. The heavy metal concentration in mosses reflected local emission sources. The data obtained in this study were compared with those of similar studies in neighboring countries and Europe (2010-2014 survey). The geographical distribution maps of the elements over the sampled territory were constructed using geographic information system (GIS) technology. The concentrations of Cr, Ni, Pb, and Zn were higher than the respective median values of Europe, suggesting that the zones with heavy vehicular traffic and industry emission input are important emitters of these elements. Selected zones are highly polluted particularly by Cd, Pb, Hg, and Ni. The statistical analyses revealed that a strong correlation exists between the Pb and Cd content in mosses, and the degree of pollution in the studied sites was assessed.

  8. Wetting layer of copper on the tantalum (001) surface

    Science.gov (United States)

    Dupraz, Maxime; Poloni, Roberta; Ratter, Kitti; Rodney, David; De Santis, Maurizio; Gilles, Bruno; Beutier, Guillaume; Verdier, Marc

    2016-12-01

    The heteroepitaxial interface formed by copper deposited onto the tantalum (001) surface is studied by surface x-ray diffraction and ab initio calculations. The analysis of the crystal truncation rods reveals the presence of a wetting layer of copper made of two atomic planes pseudomorphic to the tantalum substrate, with the upper most atomic planes significantly deformed. These findings are in total agreement with the results of density-functional-theory calculations. The presence of the wetting layer confirms a Stranski-Krastanov growth mode and is thought to explain the extremely fast atomic diffusion of copper during the dewetting process in the solid state at high temperature.

  9. Novel methodology for the study of mercury methylation and reduction in sediments and water using {sup 197}Hg radiotracer

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro Guevara, Sergio; Perez Catan, Soledad [Centro Atomico Bariloche, Laboratorio de Analisis por Activacion Neutronica, Bariloche (Argentina); Zizek, Suzana; Repinc, Urska; Jacimovic, Radojko; Horvat, Milena [Jozef Stefan Institute, Department of Environmental Sciences, Ljubljana (Slovenia)

    2007-03-15

    the present work, {sup 197}Hg tracer was produced from mercury 51.58% enriched in the {sup 196}Hg isotope, and a 340-fold increase in specific activity with respect to natural mercury targets was obtained. When this high specific activity tracer is employed, mercury methylation and reduction experiments with minimum mercury additions are feasible. Tracer recovery in methylation experiments (associated with Me{sup 197}Hg production from {sup 197}Hg{sup 2+} spike, but also with Hg{sup 2+} contamination and Me{sup 197}Hg artefacts) with marine sediments was about 0.005% g{sup -1} WS (WS: wet sediment) after 20 h incubation with mercury additions of 0.05 ng g{sup -1} WS, which is far below natural mercury levels. (orig.)

  10. Relationship Between Soil Properties and Different Fractions of Soil Hg

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Correlation and path analysis methods were used to study the relationship between soil properties and the distribution of different soil Hg fractions with nine representative soils from Chongqing, China. Results showed that clay (< 2 m) could increase water-soluble Hg (r = 0.700*). Soil organic matter (OM) could enhance the increase of elemental Hg (r = 0.674*). The higher the base saturation percentage (BSP), the more the residual Hg (r = 0.684*). Organic Hg, the sum of acid-soluble organic Hg. and alkali-soluble Hg, was positively affected by silt (2~20μm) but negatively affected by pH, with the direct path coefficients amounting to 1.0487 and 0.5121, respectively. The positive effect of OM and negative effect of BSP on organic Hg were the most significant, with the direct path coefficients being 0.7614 and -0.8527, respectively. The indirect effect of clay (< 2 μm) via BSP (path coefficient = 0.4186) was the highest, showing that the real influencing factor in the effect of clay (< 2 μm) on acid-soluble organic Hg was BSP. Since the available Hg fraction, water-soluble Hg, was positively affected by soil clay content, and the quite immobile and not bioavailable residual Hg by soil BSP, suitable reduction of clay content and increase of BSP would be of much help to reduce the Hg availability and Hg activity in Hg-contaminated soils.

  11. Particulate-phase mercury emissions from biomass burning and impact on resulting deposition: a modelling assessment

    Science.gov (United States)

    De Simone, Francesco; Artaxo, Paulo; Bencardino, Mariantonia; Cinnirella, Sergio; Carbone, Francesco; D'Amore, Francesco; Dommergue, Aurélien; Feng, Xin Bin; Gencarelli, Christian N.; Hedgecock, Ian M.; Landis, Matthew S.; Sprovieri, Francesca; Suzuki, Noriuki; Wängberg, Ingvar; Pirrone, Nicola

    2017-02-01

    Mercury (Hg) emissions from biomass burning (BB) are an important source of atmospheric Hg and a major factor driving the interannual variation of Hg concentrations in the troposphere. The greatest fraction of Hg from BB is released in the form of elemental Hg (Hg0(g)). However, little is known about the fraction of Hg bound to particulate matter (HgP) released from BB, and the factors controlling this fraction are also uncertain. In light of the aims of the Minamata Convention to reduce intentional Hg use and emissions from anthropogenic activities, the relative importance of Hg emissions from BB will have an increasing impact on Hg deposition fluxes. Hg speciation is one of the most important factors determining the redistribution of Hg in the atmosphere and the geographical distribution of Hg deposition. Using the latest version of the Global Fire Emissions Database (GFEDv4.1s) and the global Hg chemistry transport model, ECHMERIT, the impact of Hg speciation in BB emissions, and the factors which influence speciation, on Hg deposition have been investigated for the year 2013. The role of other uncertainties related to physical and chemical atmospheric processes involving Hg and the influence of model parametrisations were also investigated, since their interactions with Hg speciation are complex. The comparison with atmospheric HgP concentrations observed at two remote sites, Amsterdam Island (AMD) and Manaus (MAN), in the Amazon showed a significant improvement when considering a fraction of HgP from BB. The set of sensitivity runs also showed how the quantity and geographical distribution of HgP emitted from BB has a limited impact on a global scale, although the inclusion of increasing fractions HgP does limit Hg0(g) availability to the global atmospheric pool. This reduces the fraction of Hg from BB which deposits to the world's oceans from 71 to 62 %. The impact locally is, however, significant on northern boreal and tropical forests, where fires are

  12. Solubility of deposited airborne heavy metals

    Science.gov (United States)

    Cizmecioglu, Sibel C.; Muezzinoglu, Aysen

    2008-09-01

    Toxic effects of heavy metals in water and soil environments are important. Quantifying the heavy metal concentrations and their solubilities in dry and wet deposition samples is part of atmospheric research. Soluble fractions of the deposited air pollutants are important in food chain mechanisms as heavy metals may cause ecotoxic impacts. In this study, the solubilities of Cr, Cd, Pb, Cu, Zn, and Ni were investigated in deposition samples for total, dissolved, and suspended fractions after collection in a surrogate, water-surface sampler in Izmir, Turkey, during October 2003 to June 2004. To find overall solubility of each metal in dry and wet deposition samples, concentrations in soluble and suspended phases of aqueous solutions were analyzed separately. Ratios between total and dissolved forms and the metals in the same forms were analyzed and evaluated statistically. It was found that the deposited metal fluxes were significantly correlated in wet deposition with the highest correlation between Cd and Pb in the soluble and total forms. Comparatively smaller correlations were found between these metal fluxes in dry deposition samples. Results of this study showed the importance of metal pollution, especially ecotoxic properties of heavy metals in wet deposition far more than dry deposition.

  13. Hg/HgO electrode and hydrogen evolution potentials in aqueous sodium hydroxide

    Energy Technology Data Exchange (ETDEWEB)

    Nickell, Ryan A.; Zhu, Wenhua H.; Payne, Robert U.; Cahela, Donald R.; Tatarchuk, Bruce J. [Center for Microfibrous Materials Manufacturing, Department of Chemical Engineering, 230 Ross Hall, Auburn University, Auburn, AL 36849 (United States)

    2006-10-27

    The Hg/HgO electrode is usually utilized as a reference electrode in alkaline solution such as for development of an alkaline hydrogen electrode. The reference electrode provides a suitable reference point but is available from few commercial vendors and suffers from inadequate documentation on potential in varying electrolytes. A new numerical method uses activity, activity coefficients, and a few correlated empirical equations to determine the potential values in both dilute and concentrated sodium hydroxide solutions at temperatures of 0-90{sup o}C and at concentrations of 0.100-12.8mol kg{sub H{sub 2}O}{sup -1}. The computed potentials of the Hg/HgO electrodes versus a normal hydrogen electrode (NHE) at 25{sup o}C and 1atm are 0.1634V for 0.100m, 0.1077V for 1.00m, and 0.0976V for 1.45m NaOH solutions. The Hg/HgO reduction potential further changes to -0.0751V versus NHE and hydrogen evolution potential changes to -0.9916V versus NHE in a solution of 30.0wt.% NaOH at 80{sup o}C. The calculated values are compared with the measured data at 25 and 75{sup o}C. The experimental data agree well with the numerical values computed from the theoretical and empirical equations. (author)

  14. Hg/HgO electrode and hydrogen evolution potentials in aqueous sodium hydroxide

    Science.gov (United States)

    Nickell, Ryan A.; Zhu, Wenhua H.; Payne, Robert U.; Cahela, Donald R.; Tatarchuk, Bruce J.

    The Hg/HgO electrode is usually utilized as a reference electrode in alkaline solution such as for development of an alkaline hydrogen electrode. The reference electrode provides a suitable reference point but is available from few commercial vendors and suffers from inadequate documentation on potential in varying electrolytes. A new numerical method uses activity, activity coefficients, and a few correlated empirical equations to determine the potential values in both dilute and concentrated sodium hydroxide solutions at temperatures of 0-90 °C and at concentrations of 0.100-12.8 mol k gH2O-1 . The computed potentials of the Hg/HgO electrodes versus a normal hydrogen electrode (NHE) at 25 °C and 1 atm are 0.1634 V for 0.100m, 0.1077 V for 1.00m, and 0.0976 V for 1.45m NaOH solutions. The Hg/HgO reduction potential further changes to -0.0751 V versus NHE and hydrogen evolution potential changes to -0.9916 V versus NHE in a solution of 30.0 wt.% NaOH at 80 °C. The calculated values are compared with the measured data at 25 and 75 °C. The experimental data agree well with the numerical values computed from the theoretical and empirical equations.

  15. Long-term Hg pollution induced Hg tolerance in the terrestrial isopod Porcellio scaber (Isopoda, Crustacea)

    Energy Technology Data Exchange (ETDEWEB)

    Lapanje, A. [University of Ljubljana, Biotechnical Faculty, Department of Biology, Vecna pot 111, 1000 Ljubljana (Slovenia); Institute of Physical Biology, Veliko Mlacevo 59, 1290 Grosuplje (Slovenia)], E-mail: ales.lapanje@bf.uni-lj.si; Drobne, D. [University of Ljubljana, Biotechnical Faculty, Department of Biology, Vecna pot 111, 1000 Ljubljana (Slovenia); Nolde, N. [Institute Jozef Stefan, Department of Environmental Sciences, Jamova 39, 1000 Ljubljana (Slovenia); Valant, J. [University of Ljubljana, Biotechnical Faculty, Department of Biology, Vecna pot 111, 1000 Ljubljana (Slovenia); Muscet, B. [Institute of Physical Biology, Veliko Mlacevo 59, 1290 Grosuplje (Slovenia); Leser, V. [University of Ljubljana, Biotechnical Faculty, Department of Biology, Vecna pot 111, 1000 Ljubljana (Slovenia); Rupnik, M. [Institute of Public Health, Prvomajska 1, 2000 Maribor (Slovenia); Faculty of Medicine, University of Maribor, Slomskov trg 15, 2000 Maribor (Slovenia)

    2008-06-15

    The aim of our work was to assess the pollution-induced community tolerance (PICT) of isopod gut microbiota and pollution-induced isopod population tolerance (PIPT). Animals collected from a chronically Hg polluted and an unpolluted location were exposed for 14 days to 10 {mu}g Hg/g dry food under laboratory conditions. The lysosomal membrane stability, hepatopancreas epithelium thickness, feeding activity and animal bacterial gut microbiota composition were determined. The results confirm the hypothesis that the response to short-term Hg exposure differs for animals from the Hg polluted and the unpolluted field locations. The animals and their gut microbiota from the Hg polluted location were less affected by Hg in a short-term feeding experiment than those from the unpolluted environment. We discuss the pollution-induced population tolerance of isopods and their gut microbiota as a measure of effects of long-term environmental pollution. The ecological consequences of such phenomena are also discussed. - Isopods (Porcellio scaber) as well as their bacterial gut community from a mercury-polluted site are mercury tolerant.

  16. Mercury stable isotope signatures of world coal deposits and historical coal combustion emissions.

    Science.gov (United States)

    Sun, Ruoyu; Sonke, Jeroen E; Heimbürger, Lars-Eric; Belkin, Harvey E; Liu, Guijian; Shome, Debasish; Cukrowska, Ewa; Liousse, Catherine; Pokrovsky, Oleg S; Streets, David G

    2014-07-01

    Mercury (Hg) emissions from coal combustion contribute approximately half of anthropogenic Hg emissions to the atmosphere. With the implementation of the first legally binding UNEP treaty aimed at reducing anthropogenic Hg emissions, the identification and traceability of Hg emissions from different countries/regions are critically important. Here, we present a comprehensive world coal Hg stable isotope database including 108 new coal samples from major coal-producing deposits in South Africa, China, Europe, India, Indonesia, Mongolia, former USSR, and the U.S. A 4.7‰ range in δ(202)Hg (-3.9 to 0.8‰) and a 1‰ range in Δ(199)Hg (-0.6 to 0.4‰) are observed. Fourteen (p coal Hg emissions tracing. A revised coal combustion Hg isotope fractionation model is presented, and suggests that gaseous elemental coal Hg emissions are enriched in the heavier Hg isotopes relative to oxidized forms of emitted Hg. The model explains to first order the published δ(202)Hg observations on near-field Hg deposition from a power plant and global scale atmospheric gaseous Hg. Yet, model uncertainties appear too large at present to permit straightforward Hg isotope source identification of atmospheric forms of Hg. Finally, global historical (1850-2008) coal Hg isotope emission curves were modeled and indicate modern-day mean δ(202)Hg and Δ(199)Hg values for bulk coal emissions of -1.2 ± 0.5‰ (1SD) and 0.05 ± 0.06‰ (1SD).

  17. MBE HgCdTe heterostructure detectors

    Science.gov (United States)

    Schulman, Joel N.; Wu, Owen K.

    1990-01-01

    HgCdTe has been the mainstay for medium (3 to 5 micron) and long (10 to 14 micron) wavelength infrared detectors in recent years. Conventional growth and processing techniques are continuing to improve the material. However, the additional ability to tailor composition and placement of doped layers on the tens of angstroms scale using molecular beam epitaxy (MBE) provides the opportunity for new device physics and concepts to be utilized. MBE-based device structures to be discussed here can be grouped into two categories: tailored conventional structures and quantum structures. The tailored conventional structures are improvements on familiar devices, but make use of the ability to create layers of varying composition, and thus band gap, at will. The heterostructure junction can be positioned independently of doping p-n junctions. This allows the small band gap region in which the absorption occurs to be separated from a larger band gap region in which the electric field is large and where unwanted tunneling can occur. Data from hybrid MBE/liquid phase epitaxy (LPE)/bulk structures are given. Quantum structures include the HgTe-CdTe superlattice, in which the band gap and transport can be controlled by alternating thin layers (tens of angstroms thick) of HgTe and CdTe. The superlattice has been shown to exhibit behavior which is non-alloy like, including very high hole mobilities, two-dimensional structure in the absorption coefficient, resonant tunneling, and anisotropic transport.

  18. [Monitoring nitrogen deposition on temperate grassland in Inner Mongolia].

    Science.gov (United States)

    Zhang, Ju; Kang, Rong-hua; Zhao, Bin; Huang, Yong-mei; Ye, Zhi-xiang; Duan, Lei

    2013-09-01

    Nitrogen deposition on temperate steppe was monitored from November 2011 to October 2012 in Taipusi County, Inner Mongolia. The dry deposition of gaseous nitrogen compounds was calculated based on online-monitored atmospheric concentrations of NH3 and NO2 and dry deposition velocity simulated by CMAQ model. The wet deposition, dry deposition of particle, and throughfall deposition were also estimated by collecting rainfall, dust fall, and throughfall samples and the chemical analysis of NH4+ and NO3-concentrations. Results showed that the total deposition of nitrogen was up to 3.43 g x (m2 x a)(-1), which might be harmful to the ecosystem. The wet deposition accounted for about 44% of the total deposition, while dry deposition of gases and particle accounted for 38% and 18%, respectively. Since the deposition contributed more than wet deposition, a great attention should be paid on dry deposition monitoring. However, the very simple method for total deposition monitoring based on throughfall seemed not suitable for grassland because the monitored throughfall deposition was much lower than the total deposition. In addition, reduced nitrogen (NH4+ and NH3) contributed to 71% of the total deposition, while oxidation nitrogen (NO3- and NO2) was only 29%. Therefore, NH3 emission reduction should be considered as important as nitrogen oxides (NO3x) for controlling nitrogen deposition.

  19. SETAC-U.S. EPA WET INITIATIVES: ALL WET AND NOTHING BUT WET

    Science.gov (United States)

    To ensure that sould scientific principles and sound science are applied to the challenging issues in t he Whole Effluent Toxicity (WET) process, the Society of Environmental Toxicology and Chemistry (SETAC) Foundation for Environmental Education was awarded a cooperative agreem...

  20. SETAC-U.S. EPA WET INITIATIVES: ALL WET AND NOTHING BUT WET

    Science.gov (United States)

    To ensure that sould scientific principles and sound science are applied to the challenging issues in t he Whole Effluent Toxicity (WET) process, the Society of Environmental Toxicology and Chemistry (SETAC) Foundation for Environmental Education was awarded a cooperative agreem...

  1. Total Sulfur Deposition (wet+dry) from the Atmosphere

    Data.gov (United States)

    U.S. Environmental Protection Agency — Sulfur Dioxide (SO2) is emitted primarily as a by-product of coal combustion from power plants. Sulfur Dioxide reacts in the atmosphere to form other chemical such...

  2. Total Nitrogen Deposition (wet+dry) from the Atmosphere

    Data.gov (United States)

    U.S. Environmental Protection Agency — Oxides of Nitrogen are emitted primarily as by-products of combustion. Sources include power plants, industrial boilers, and automobiles. In addition, agricultural...

  3. The use of Pb, Sr, and Hg isotopes in Great Lakes precipitation as a tool for pollution source attribution

    Energy Technology Data Exchange (ETDEWEB)

    Sherman, Laura S., E-mail: lsaylors@umich.edu [University of Michigan, Department of Earth and Environmental Sciences, 1100 N. University Ave., Ann Arbor, MI 48109 (United States); Blum, Joel D. [University of Michigan, Department of Earth and Environmental Sciences, 1100 N. University Ave., Ann Arbor, MI 48109 (United States); Dvonch, J. Timothy [University of Michigan, Air Quality Laboratory, 1415 Washington Heights, Ann Arbor, MI 48109 (United States); Gratz, Lynne E. [University of Washington-Bothell, 18115 Campus Way NE, Bothell, WA 98011 (United States); Landis, Matthew S. [U.S. EPA, Office of Research and Development, Research Triangle Park, NC 27709 (United States)

    2015-01-01

    The anthropogenic emission and subsequent deposition of heavy metals including mercury (Hg) and lead (Pb) present human health and environmental concerns. Although it is known that local and regional sources of these metals contribute to deposition in the Great Lakes region, it is difficult to trace emissions from point sources to impacted sites. Recent studies suggest that metal isotope ratios may be useful for distinguishing between and tracing source emissions. We measured Pb, strontium (Sr), and Hg isotope ratios in daily precipitation samples that were collected at seven sites across the Great Lakes region between 2003 and 2007. Lead isotope ratios ({sup 207}Pb/{sup 206}Pb = 0.8062 to 0.8554) suggest that Pb deposition was influenced by coal combustion and processing of Mississippi Valley-Type Pb ore deposits. Regional differences in Sr isotope ratios ({sup 87}Sr/{sup 86}Sr = 0.70859 to 0.71155) are likely related to coal fly ash and soil dust. Mercury isotope ratios (δ{sup 202}Hg = − 1.13 to 0.13‰) also varied among the sites, likely due to regional differences in coal isotopic composition, and fractionation occurring within industrial facilities and in the atmosphere. These data represent the first combined characterization of Pb, Sr, and Hg isotope ratios in precipitation collected across the Great Lakes region. We demonstrate the utility of multiple metal isotope ratios in parallel with traditional trace element multivariate statistical modeling to enable more complete pollution source attribution. - Highlights: • We measured Pb, Sr, and Hg isotopes in precipitation from the Great Lakes region. • Pb isotopes suggest that deposition was impacted by coal combustion and metal production. • Sr isotope ratios vary regionally, likely due to soil dust and coal fly ash. • Hg isotopes vary due to fractionation occurring within facilities and the atmosphere. • Isotope results support conclusions of previous trace element receptor modeling.

  4. Characterization of soil fauna under the influence of mercury atmospheric deposition in Atlantic Forest, Rio de Janeiro, Brazil.

    Science.gov (United States)

    Buch, Andressa Cristhy; Correia, Maria Elizabeth Fernandes; Teixeira, Daniel Cabral; Silva-Filho, Emmanoel Vieira

    2015-06-01

    The increasing levels of mercury (Hg) found in the atmosphere arising from anthropogenic sources, have been the object of great concern in the past two decades in industrialized countries. Brazil is the seventh country with the highest rate of mercury in the atmosphere. The major input of Hg to ecosystems is through atmospheric deposition (wet and dry), being transported in the atmosphere over large distances. The forest biomes are of strong importance in the atmosphere/soil cycling of elemental Hg through foliar uptake and subsequent transference to the soil through litter, playing an important role as sink of this element. Soil microarthropods are keys to understanding the soil ecosystem, and for such purpose were characterized by the soil fauna of two Units of Forest Conservation of the state of the Rio de Janeiro, inwhich one of the areas suffer quite interference from petrochemicals and industrial anthropogenic activities and other area almost exempts of these perturbations. The results showed that soil and litter of the Atlantic Forest in Brazil tend to stock high mercury concentrations, which could affect the abundance and richness of soil fauna, endangering its biodiversity and thereby the functioning of ecosystems. Copyright © 2015. Published by Elsevier B.V.

  5. Hg Vetical Transference in Soil—Water System

    Institute of Scientific and Technical Information of China (English)

    GUOYIJUN; MOUSUSEN; 等

    1998-01-01

    Hg vertial transference in soil-water system was studied by analyzing Hg vertical ditribution in soil column after adding Hg and one of the two leacheates,deionzied water or acid rain,into soil column.The results indicated that Hg was hardly transferable in puple soil.About 86%-88% of the total soil Hg was distributed in the top layer (0-2cm) and to Hg was detected in the leakage when the purple soil column was leached by deionized water and simulated acid rain.But Hg was more movalbe in yellow soil with only about 20%-22% of the total soil Hg distributed in the top layer (0-2cm),and about 17%-25% washed out from the soil column by deionized water and simulted acid rain,Incremant in soil bulk density colud reduce Hg leaching,thus the more the Hg kept in soil,the less the Hg leached into underground water,Deionized water and acid rain almost played the same role in leaching Hg.Bentioint was most effecient in preventing Hg from vertcal transferring in the soil coulumn.

  6. Quantitative imaging of D-2-hydroxyglutarate (D2HG in selected histological tissue areas by a novel bioluminescence technique

    Directory of Open Access Journals (Sweden)

    Nadine Fabienne Voelxen

    2016-03-01

    Full Text Available AbstractPatients with malignant gliomas have a poor prognosis with average survival of less than one year. Whereas in other tumor entities the characteristics of tumor metabolism are successfully used for therapeutic approaches, such developments are very rare in brain tumors, notably in gliomas. One metabolic feature characteristic of gliomas, in particular diffuse astrocytomas and oligodendroglial tumors, is the variable content of D-2-hydroxyglutarate (D2HG, a metabolite, which was discovered first in this tumor entity. D2HG is generated in large amounts due to various gain-of–function mutations in the isocitrate dehydrogenases IDH-1 and IDH-2. Meanwhile, D2HG has been detected in several other tumor entities including intrahepatic bile-duct cancer, chondrosarcoma, acute myeloid leukemia, and angioimmunoblastic T-cell lymphoma. D2HG is barely detectable in healthy tissue (< 0.1 mM, but its concentration increases up to 35 mM in malignant tumor tissues. Consequently, the oncometabolite D2HG has gained increasing interest in the field of tumor metabolism. To facilitate its quantitative measurement without loss of spatial resolution at a microscopical level, we have developed a novel bioluminescence assay for determining D2HG in sections of snap-frozen tissue. The assay was verified independently by photometric tests and liquid chromatography / mass spectrometry (LC/MS. The novel technique allows the microscopically resolved determination of D2HG in a concentration range of 0 – 10 µmol/g tissue (wet weight. In combination with the already established bioluminescence imaging techniques for ATP, glucose, pyruvate, and lactate, the novel D2HG assay enables a comparative characterization of the metabolic profile of individual tumors in a further dimension.

  7. Automated product recovery in a Hg-196 photochemical isotope separation process

    Science.gov (United States)

    Grossman, M.W.; Speer, R.

    1992-07-21

    A method of removing deposited product from a photochemical reactor used in the enrichment of [sup 196]Hg has been developed and shown to be effective for rapid re-cycling of the reactor system. Unlike previous methods relatively low temperatures are used in a gas and vapor phase process of removal. Importantly, the recovery process is understood in a quantitative manner so that scaling design to larger capacity systems can be easily carried out. 2 figs.

  8. Litterfall mercury dry deposition in the eastern USA

    Science.gov (United States)

    Martin R. Risch; John F. DeWild; David P. Krabbenhoft; Randall K. Kolka; Leiming. Zhang

    2012-01-01

    Mercury (Hg) in autumn litterfall frompredominately deciduous forestswas measured in 3 years of samples from 23 Mercury Deposition Network sites in 15 states across the eastern USA. Annual litterfall Hg dry depositionwas significantly higher (median 12.3 micrograms per square meter (µg/m2), range 3.5-23.4 µg/m2...

  9. Squeezing wetting and nonwetting liquids.

    Science.gov (United States)

    Samoilov, V N; Persson, B N J

    2004-01-22

    We present molecular-dynamics results for the squeezing of octane (C8H18) between two approaching solid elastic walls with different wetting properties. The interaction energy between the octane bead units and the solid walls is varied from a very small value (1 meV), corresponding to a nonwetting surface with a very large contact angle (nearly 180 degrees), to a high value (18.6 meV) corresponding to complete wetting. When at least one of the solid walls is wetted by octane we observe well defined molecular layers develop in the lubricant film when the thickness of the film is of the order of a few atomic diameters. An external squeezing-pressure induces discontinuous, thermally activated changes in the number n of lubricant layers (n-->n-1 layering transitions). With increasing interaction energy between the octane bead units and the solid walls, the transitions from n to n-1 layers occur at higher average pressure. This results from the increasing activation barrier to nucleate the squeeze-out with increasing lubricant-wall binding energy (per unit surface area) in the contact zone. Thus, strongly wetting lubricant fluids are better boundary lubricants than the less wetting ones, and this should result in less wear. We analyze in detail the effect of capillary bridge formation (in the wetting case) and droplets formation (in the nonwetting case) on the forces exerted by the lubricant on the walls. For the latter case small liquid droplets may be trapped at the interface, resulting in a repulsive force between the walls during squeezing, until the solid walls come into direct contact, where the wall-wall interaction may be initially attractive. This effect is made use of in some practical applications, and we give one illustration involving conditioners for hair care application.

  10. Process of [sup 196]Hg enrichment

    Science.gov (United States)

    Grossman, M.W.; Mellor, C.E.

    1993-04-27

    A simple rate equation model shows that by increasing the length of the photochemical reactor and/or by increasing the photon intensity in said reactor, the feedstock utilization of [sup 196]Hg will be increased. Two preferred embodiments of the present invention are described, namely (1) long reactors using long photochemical lamps and vapor filters; and (2) quartz reactors with external UV reflecting films. These embodiments have each been constructed and operated, demonstrating the enhanced utilization process dictated by the mathematical model (also provided).

  11. Process of .sup.196 Hg enrichment

    Science.gov (United States)

    Grossman, Mark W.; Mellor, Charles E.

    1993-01-01

    A simple rate equation model shows that by increasing the length of the photochemical reactor and/or by increasing the photon intensity in said reactor, the feedstock utilization of .sup.196 Hg will be increased. Two preferred embodiments of the present invention are described, namely (1) long reactors using long photochemical lamps and vapor filters; and (2) quartz reactors with external UV reflecting films. These embodiments have each been constructed and operated, demonstrating the enhanced utilization process dictated by the mathematical model (also provided).

  12. Magnetic fields of HgMn stars

    DEFF Research Database (Denmark)

    Hubrig, S.; González, J. F.; Ilyin, I.

    2012-01-01

    Context. The frequent presence of weak magnetic fields on the surface of spotted late-B stars with HgMn peculiarity in binary systems has been controversial during the two last decades. Recent studies of magnetic fields in these stars using the least-squares deconvolution (LSD) technique have...... failed to detect magnetic fields, indicating an upper limit on the longitudinal field between 8 and 15G. In these LSD studies, assumptions were made that all spectral lines are identical in shape and can be described by a scaled mean profile. Aims. We re-analyse the available spectropolarimetric material...

  13. Of Variability, or its Absence, in HgMn Stars

    CERN Document Server

    Turcotte, S

    2003-01-01

    Current models and observations of variability in HgMn stars disagree. We present here the models that argue for pulsating HgMn stars with properties similar to those of Slowly Pulsating B Stars. The lack of observed variable HgMn stars suggests that some physical process is missing from the models. Some possibilities are discussed.

  14. Wet flue gas desulfurization processes

    Directory of Open Access Journals (Sweden)

    Hayrunnisa Çavuşoğlu

    2013-04-01

    Full Text Available The wet flue gas desulfurization process is widely used for the treatment of exhaust gases in power stations. Due to its high level of effectiveness over the already available processes, it has also been the mostly preferred method by industry. Its high SO2 removal efficiency, wide applicability of absorption chemicals and the ease of the chemical process handling which does not require comprehensive konowledge are among the main advantages of this process. In this article, various wet flue gas desulfurization processes such as lime/limestone have beendiscussed.

  15. HgZnTe-based detectors for LWIR NASA applications

    Science.gov (United States)

    Patten, Elizabeth A.; Kalisher, Murray H.

    1990-01-01

    The initial goal was to grow and characterize HgZnTe and determine if it indeed had the advantageous properties that were predicted. Researchers grew both bulk and liquid phase epitaxial HgZnTe. It was determined that HgZnTe had the following properties: (1) microhardness at least 50 percent greater than HgCdTe of equivalent bandgap; (2) Hg annealing rates of at least 2 to 4 times longer than HgCdTe; and (3) higher Hg vacancy formation energies. This early work did not focus on one specific composition (x-value) of HgZnTe since NASA was interested in HgZnTe's potential for a variety of applications. Since the beginning of 1989, researchers have been concentrating, however, on the liquid phase growth of very long wavelength infrared (VLWIR) HgZnTe (cutoff approx. equals 17 microns at 65K) to address the requirements of the Earth Observing System (EOS). Since there are no device models to predict the advantages in reliability one can gain with increased microhardness, surface stability, etc., one must fabricate HgZnTe detectors and assess their relative bake stability (accelerated life test behavior) compared with HgCdTe devices fabricated in the same manner. Researchers chose to fabricate HIT detectors as a development vehicle for this program because high performance in the VLWIR has been demonstrated with HgCdTe HIT detectors and the HgCdTe HIT process should be applicable to HgZnTe. HIT detectors have a significant advantage for satellite applications since these devices dissipate much less power than conventional photoconductors to achieve the same responsivity.

  16. Fully relativistic coupled cluster and DFT study of electric field gradients at Hg in 199Hg compounds

    DEFF Research Database (Denmark)

    Arcisauskaité, Vaida; Knecht, Stefan; Sauer, Stephan P. A.

    2012-01-01

    We investigate the magnitude and interplay of relativistic and electron correlation effects on the electric field gradient (EFG) at the position of Hg in linear and bent HgL2 (L=CH3, Cl, Br, I) and trigonal planar [HgCl3]- complexes using four-component relativistic Dirac-Coulomb (DC) and non...

  17. The Chevrel phase HgMo6S8

    Directory of Open Access Journals (Sweden)

    Michel Potel

    2009-05-01

    Full Text Available The crystal structure of HgMo6S8, mercury(II hexamolybdenum octasulfide, is based on (Mo6S8S6 cluster units (overline{3} symmetry interconnected through interunit Mo—S bonds. The Hg2+ cations occupy large voids between the different cluster units and are covalently bonded to two S atoms. The Hg atoms and one S atom lie on sites with crystallographic overline{3} and 3 symmetry, respectively. Refinement of the occupancy factor of the Hg atom led to the composition Hg0.973 (3Mo6S8.

  18. Inhibiting Wet Oxidation of Ammonia

    Science.gov (United States)

    Onisko, D. B. L.

    1985-01-01

    Simple modification of wet-oxidation process for treating organicwaste reduces loss of fixed nitrogen, potentially valuable byproduct of process. Addition of sufficient sulfuric acid to maintain reaction pH below 3 greatly reduces oxidation of ammonia to free nitrogen. No equipment modification required.

  19. Wedge wetting by electrolyte solutions

    Science.gov (United States)

    Mußotter, Maximilian; Bier, Markus

    2017-09-01

    The wetting of a charged wedgelike wall by an electrolyte solution is investigated by means of classical density functional theory. As in other studies on wedge wetting, this geometry is considered as the most simple deviation from a planar substrate, and it serves as a first step toward more complex confinements of fluids. By focusing on fluids containing ions and surface charges, features of real systems are covered that are not accessible within the vast majority of previous theoretical studies concentrating on simple fluids in contact with uncharged wedges. In particular, the filling transition of charged wedges is necessarily of first order, because wetting transitions of charged substrates are of first order and the barrier in the effective interface potential persists below the wetting transition of a planar wall; hence, critical filling transitions are not expected to occur for ionic systems. The dependence of the critical opening angle on the surface charge, as well as the dependence of the filling height, of the wedge adsorption, and of the line tension on the opening angle and on the surface charge are analyzed in detail.

  20. Superdeformation studies in {sup 191}Hg

    Energy Technology Data Exchange (ETDEWEB)

    Carpenter, M.P.; Janssens, R.V.F.; Crowell, B. [and others

    1995-08-01

    Superdeformation in the A {approximately} 190 region was first observed in {sup 191}Hg from an experiment performed at ATLAS using the Argonne Notre Dame {gamma}-ray facility. We recently revisited the study of superdeformation in this nucleus using Gammasphere and the {sup 160}Gd({sup 36}S,5n) and {sup 174}Yb({sup 22}Ne,5n) reactions at 172 and 120 MeV in order to populate and measure states in the second well. The goal of the experiment was to identify new bands in the data, and thus allow us to gain understanding on the relative placement of single particle orbitals near the N = 112 SD shell gap. From an analysis of the data, the three previously identified SD bands were extended, and their feeding into the yrast states delineated. Two new SD bands were observed and preliminary evidence for a third new band was obtained as well.

  1. Effects of mercury deposition and coniferous forests on the mercury contamination of fish in the South Central United States.

    Science.gov (United States)

    Drenner, Ray W; Chumchal, Matthew M; Jones, Christina M; Lehmann, Christopher M B; Gay, David A; Donato, David I

    2013-02-05

    Mercury (Hg) is a toxic metal that is found in aquatic food webs and is hazardous to human and wildlife health. We examined the relationship between Hg deposition, land coverage by coniferous and deciduous forests, and average Hg concentrations in largemouth bass (Micropterus salmoides)-equivalent fish (LMBE) in 14 ecoregions located within all or part of six states in the South Central U.S. In 11 ecoregions, the average Hg concentrations in 35.6-cm total length LMBE were above 300 ng/g, the threshold concentration of Hg recommended by the U.S. Environmental Protection Agency for the issuance of fish consumption advisories. Percent land coverage by coniferous forests within ecoregions had a significant linear relationship with average Hg concentrations in LMBE while percent land coverage by deciduous forests did not. Eighty percent of the variance in average Hg concentrations in LMBE between ecoregions could be accounted for by estimated Hg deposition after adjusting for the effects of coniferous forests. Here we show for the first time that fish from ecoregions with high atmospheric Hg pollution and coniferous forest coverage pose a significant hazard to human health. Our study suggests that models that use Hg deposition to predict Hg concentrations in fish could be improved by including the effects of coniferous forests on Hg deposition.

  2. Can graphene make better HgCdTe infrared detectors?

    Directory of Open Access Journals (Sweden)

    Shi Yanli

    2011-01-01

    Full Text Available Abstract We develop a simple and low-cost technique based on chemical vapor deposition from which large-size graphene films with 5-10 graphene layers can be produced reliably and the graphene films can be transferred easily onto HgCdTe (MCT thin wafers at room temperature. The proposed technique does not cause any thermal and mechanical damages to the MCT wafers. It is found that the averaged light transmittance of the graphene film on MCT thin wafer is about 80% in the mid-infrared bandwidth at room temperature and 77 K. Moreover, we find that the electrical conductance of the graphene film on the MCT substrate is about 25 times larger than that of the MCT substrate at room temperature and 77 K. These experimental findings suggest that, from a physics point of view, graphene can be utilized as transparent electrodes as a replacement for metal electrodes while producing better and cheaper MCT infrared detectors.

  3. Relationship Between Soil Properties and Different Fractions of Soil Hg

    Institute of Scientific and Technical Information of China (English)

    WUHONGTAO; YUGUIFEN; 等

    2001-01-01

    Correlation and path analysis methods were used to study the relationship between soil properties and the distribution of different soil Hg fractions with nine representative soils from Chongqing,China,Results showed that clay(<2m) could increase water-soluble Hg(r=0.700*).Soil organic matter (OM) could enhance the increase of elemental Hg(r=0.674*),The higher the base saturation percentage (BSP) ,the more the residual Hg(R=0.684*) .Organic Hg,the sum of said-soluble organic He and alkali-soluble Hg,was positively affected by silt(2-20μm)but negatively affected by pH,with the direct path coefficients amounting to 1.0487 and 0.5121,respectively .The positive effect of OM and negative effect of BSP on organic Hg were the most significant ,with the direct path coefficients being 0.7614 and -0.8527,respectively. The indirect effect of clay(<2μm) iva BSP (path coefficient=0.4186) was the highest,showing that the real influencing factor in the effect of clay(<2μm) via BSP (path coefficient=0.4186) was the highest,showing that the real influencing factor in the effect of clay(<2μm) on acid-soluble organic Hw was BSP.since the available Hg fraction,water-soluble Hg,was positively affected by soil clay content,and the quite immobile and not bioavailable residual Hg by soil BSP,suitable reduction of clay content and increase of BSP would be of much help to reduce the Hg availability and Hg activity in Hg-contaminated soils.

  4. Wetting hysteresis induced by nanodefects.

    Science.gov (United States)

    Giacomello, Alberto; Schimmele, Lothar; Dietrich, Siegfried

    2016-01-19

    Wetting of actual surfaces involves diverse hysteretic phenomena stemming from ever-present imperfections. Here, we clarify the origin of wetting hysteresis for a liquid front advancing or receding across an isolated defect of nanometric size. Various kinds of chemical and topographical nanodefects, which represent salient features of actual heterogeneous surfaces, are investigated. The most probable wetting path across surface heterogeneities is identified by combining, within an innovative approach, microscopic classical density functional theory and the string method devised for the study of rare events. The computed rugged free-energy landscape demonstrates that hysteresis emerges as a consequence of metastable pinning of the liquid front at the defects; the barriers for thermally activated defect crossing, the pinning force, and hysteresis are quantified and related to the geometry and chemistry of the defects allowing for the occurrence of nanoscopic effects. The main result of our calculations is that even weak nanoscale defects, which are difficult to characterize in generic microfluidic experiments, can be the source of a plethora of hysteretical phenomena, including the pinning of nanobubbles.

  5. Wet water glass production plant

    Directory of Open Access Journals (Sweden)

    Stanković Mirjana S.

    2003-01-01

    Full Text Available The IGPC Engineering Department designed basic projects for a wet hydrate dissolution plant, using technology developed in the IGPC laboratories. Several projects were completed: technological, machine, electrical, automation. On the basis of these projects, a production plant of a capacity of 75,000 t/y was manufactured, at "Zeolite Mira", Mira (VE, Italy, in 1997. and 1998, increasing detergent zeolite production, from 50,000 to 100,000 t/y. Several goals were realized by designing a wet hydrate dissolution plant. The main goal was increasing the detergent zeolite production. The technological cycle of NaOH was closed, and no effluents emitted, and there is no pollution (except for the filter cake. The wet water glass production process is fully automatized, and the product has uniform quality. The production process can be controlled manually, which is necessary during start - up, and repairs. By installing additional process equipment (centrifugal pumps and heat exchangers technological bottlenecks were overcome, and by adjusting the operation of autoclaves, and water glass filters and also by optimizing the capacities of process equipment.

  6. 49 CFR 173.159 - Batteries, wet.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Batteries, wet. 173.159 Section 173.159... Batteries, wet. (a) Electric storage batteries, containing electrolyte acid or alkaline corrosive battery fluid (wet batteries), may not be packed with other materials except as provided in paragraphs (g)...

  7. Hg and As Minerals in Fluid Inclusions from the Williams Mine,Hemlo,and Their Genetic Implications

    Institute of Scientific and Technical Information of China (English)

    卢焕章; ANDDON.C.HARRIS

    2002-01-01

    The Hemlo mineralization is enigmatic compared to general Archean lode gold deposits based on the fact that is characterized by an exotic mineralogy containing elements such as As,Hg,Sb,Ba,V and Mo.The genetic concepts range from syngenetc to epigenetic types of mineralization.This reconnaissance study was designed to examine the relationshp of Hg-As minerals with respect of fluid inclusions in the Williams mine(formerly known as the Page Williams mine)covering the A and C ore zones.

  8. Anadromous char as an alternate food choice to marine animals: A synthesis of Hg concentrations, population features and other influencing factors

    Energy Technology Data Exchange (ETDEWEB)

    Evans, Marlene S., E-mail: marlene.evans@ec.gc.ca [Environment Canada, Water Science and Technology Directorate, 11 Innovation Blvd., Saskatoon SK S7N 3H5 (Canada); Muir, Derek C.G. [Environment Canada, Water Science and Technology Directorate, 867 Lakeshore Rd., Burlington, ON L7R 4A6 (Canada); Keating, Jonathan [Environment Canada, Water Science and Technology Directorate, 11 Innovation Blvd., Saskatoon SK S7N 3H5 (Canada); Wang, Xiaowa [Environment Canada, Water Science and Technology Directorate, 867 Lakeshore Rd., Burlington, ON L7R 4A6 (Canada)

    2015-03-15

    This study was conducted to confirm sporadic measurements made over the late 1970s to the early 1990s which determined that mercury (Hg) concentrations were low in anadromous char across Arctic and subarctic Canada including northern Québec and Labrador. Over 2004–2013, anadromous char populations across northern Canada were investigated at 20 sites for Hg concentrations and life history characteristics. Hg concentrations were extremely low in anadromous char muscle, typically < 0.05 μg/g (wet weight) and, at each location, generally increased with fish length, age and nitrogen isotope (δ{sup 15}N) ratio and decreased with condition factor and %lipid; correlations with carbon isotope (δ{sup 13}C) ratio were inconsistent. Location and year were significant variables influencing Hg concentrations over the study area; longitude and latitude also were significant influencing variables. Char length, weight, age, condition factor and lipid content explained additional variance. A tendency towards higher Hg concentrations with increasing latitude may be partially related to decreasing growth of char towards the north. However, Hg concentrations in char were positively correlated with growth rates suggesting that Hg concentrations in char also were higher in the more productive study areas, including to the west where mainland riverine inputs of terrestrial carbon, nutrients, and Hg were greater. The data base for assessing time trends in char was limited by the small number of years investigated at most locations, variable fish size across years, small sample size, etc. Where temporal trends were detected, they were of increase on the long term (1970s, 1980s or early 1990s to the present) but of decrease on the short term (early 2000s to present) with Nain (Labrador) showing the converse pattern. Higher Hg concentrations were also related to lower condition factor and cooler springs. Hg concentrations in anadromous char are compared with other terrestrial, aquatic

  9. Oxidative stress in MeHg-induced neurotoxicity

    Energy Technology Data Exchange (ETDEWEB)

    Farina, Marcelo, E-mail: farina@ccb.ufsc.br [Departamento de Bioquimica, Centro de Ciencias Biologicas, Universidade Federal de Santa Catarina, Florianopolis, SC (Brazil); Aschner, Michael [Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN (United States); Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN (United States); Rocha, Joao B.T., E-mail: jbtrocha@yahoo.com.br [Departamento de Quimica, Centro de Ciencias Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, RS (Brazil)

    2011-11-15

    Methylmercury (MeHg) is an environmental toxicant that leads to long-lasting neurological and developmental deficits in animals and humans. Although the molecular mechanisms mediating MeHg-induced neurotoxicity are not completely understood, several lines of evidence indicate that oxidative stress represents a critical event related to the neurotoxic effects elicited by this toxicant. The objective of this review is to summarize and discuss data from experimental and epidemiological studies that have been important in clarifying the molecular events which mediate MeHg-induced oxidative damage and, consequently, toxicity. Although unanswered questions remain, the electrophilic properties of MeHg and its ability to oxidize thiols have been reported to play decisive roles to the oxidative consequences observed after MeHg exposure. However, a close examination of the relationship between low levels of MeHg necessary to induce oxidative stress and the high amounts of sulfhydryl-containing antioxidants in mammalian cells (e.g., glutathione) have led to the hypothesis that nucleophilic groups with extremely high affinities for MeHg (e.g., selenols) might represent primary targets in MeHg-induced oxidative stress. Indeed, the inhibition of antioxidant selenoproteins during MeHg poisoning in experimental animals has corroborated this hypothesis. The levels of different reactive species (superoxide anion, hydrogen peroxide and nitric oxide) have been reported to be increased in MeHg-exposed systems, and the mechanisms concerning these increments seem to involve a complex sequence of cascading molecular events, such as mitochondrial dysfunction, excitotoxicity, intracellular calcium dyshomeostasis and decreased antioxidant capacity. This review also discusses potential therapeutic strategies to counteract MeHg-induced toxicity and oxidative stress, emphasizing the use of organic selenocompounds, which generally present higher affinity for MeHg when compared to the classically

  10. Modeling interactions of Hg(II) and bauxitic soils.

    Science.gov (United States)

    Weerasooriya, Rohan; Tobschall, Heinz J; Bandara, Atula

    2007-11-01

    The adsorptive interactions of Hg(II) with gibbsite-rich soils (hereafter SOIL-g) were modeled by 1-pK surface complexation theory using charge distribution multi-site ion competition model (CD MUSIC) incorporating basic Stern layer model (BSM) to account for electrostatic effects. The model calibrations were performed for the experimental data of synthetic gibbsite-Hg(II) adsorption. When [NaNO(3)] > or = 0.01M, the Hg(II) adsorption density values, of gibbsite, Gamma(Hg(II)), showed a negligible variation with ionic strength. However, Gamma(Hg(II)) values show a marked variation with the [Cl(-)]. When [Cl(-)] > or = 0.01M, the Gamma(Hg(II)) values showed a significant reduction with the pH. The Hg(II) adsorption behavior in NaNO(3) was modeled assuming homogeneous solid surface. The introduction of high affinity sites, i.e., >Al(s)OH at a low concentration (typically about 0.045 sites nm(-2)) is required to model Hg(II) adsorption in NaCl. According to IR spectroscopic data, the bauxitic soil (SOIL-g) is characterized by gibbsite and bayerite. These mineral phases were not treated discretely in modeling of Hg(II) and soil interactions. The CD MUSIC/BSM model combination can be used to model Hg(II) adsorption on bauxitic soil. The role of organic matter seems to play a role on Hg(II) binding when pH>8. The Hg(II) adsorption in the presence of excess Cl(-) ions required the selection of high affinity sites in modeling.

  11. Lithography process for patterning HgI2 photonic devices

    Science.gov (United States)

    Mescher, Mark J.; James, Ralph B.; Hermon, Haim

    2004-11-23

    A photolithographic process forms patterns on HgI.sub.2 surfaces and defines metal sublimation masks and electrodes to substantially improve device performance by increasing the realizable design space. Techniques for smoothing HgI.sub.2 surfaces and for producing trenches in HgI.sub.2 are provided. A sublimation process is described which produces etched-trench devices with enhanced electron-transport-only behavior.

  12. Epitaxial growth of HgTe by a MOVPE process

    Energy Technology Data Exchange (ETDEWEB)

    Irvine, S.J.C.; Mullin, J.B.; Royle, A. (Royal Signals and Radar Establishment, Malvern (UK))

    1982-03-01

    Epitaxial layers of HgTe have been grown onto insulating CdTe substrates by the pyrolysis of (C/sub 2/H/sub 5/)/sub 2/Te in the presence of Hg vapour using a H/sub 2/ flow system. Temperature-dependent Hall effect and conductivity measurements have shown that the electrical properties of the layers are comparable with good quality bulk HgTe.

  13. A 20-year simulated climatology of global dust aerosol deposition.

    Science.gov (United States)

    Zheng, Yu; Zhao, Tianliang; Che, Huizheng; Liu, Yu; Han, Yongxiang; Liu, Chong; Xiong, Jie; Liu, Jianhui; Zhou, Yike

    2016-07-01

    Based on a 20-year (1991-2010) simulation of dust aerosol deposition with the global climate model CAM5.1 (Community Atmosphere Model, version 5.1), the spatial and temporal variations of dust aerosol deposition were analyzed using climate statistical methods. The results indicated that the annual amount of global dust aerosol deposition was approximately 1161±31Mt, with a decreasing trend, and its interannual variation range of 2.70% over 1991-2010. The 20-year average ratio of global dust dry to wet depositions was 1.12, with interannual variation of 2.24%, showing the quantity of dry deposition of dust aerosol was greater than dust wet deposition. High dry deposition was centered over continental deserts and surrounding regions, while wet deposition was a dominant deposition process over the North Atlantic, North Pacific and northern Indian Ocean. Furthermore, both dry and wet deposition presented a zonal distribution. To examine the regional changes of dust aerosol deposition on land and sea areas, we chose the North Atlantic, Eurasia, northern Indian Ocean, North Pacific and Australia to analyze the interannual and seasonal variations of dust deposition and dry-to-wet deposition ratio. The deposition amounts of each region showed interannual fluctuations with the largest variation range at around 26.96% in the northern Indian Ocean area, followed by the North Pacific (16.47%), Australia (9.76%), North Atlantic (9.43%) and Eurasia (6.03%). The northern Indian Ocean also had the greatest amplitude of interannual variation in dry-to-wet deposition ratio, at 22.41%, followed by the North Atlantic (9.69%), Australia (6.82%), North Pacific (6.31%) and Eurasia (4.36%). Dust aerosol presented a seasonal cycle, with typically strong deposition in spring and summer and weak deposition in autumn and winter. The dust deposition over the northern Indian Ocean exhibited the greatest seasonal change range at about 118.00%, while the North Atlantic showed the lowest seasonal

  14. Experiments with a New 201Hg+ Ion Clock

    Science.gov (United States)

    Burt, E. A.; Taghavi-Larigani, S.; Lea, S. N.; Prestage, J. D.; Tjoelker, R. L.

    2009-04-01

    In this paper we describe a new clock based on 201Hg+. All previous mercury ion clocks have been based on 199Hg+. We have recently completed construction of the 201Hg+ clock and will describe modifications to the design of our existing 199Hg+ clocks to accommodate the new isotope. We will also describe initial spectroscopic measurements of the hyperfine manifold, and possible future experiments. One experiment could place a limit on variations in the strong interaction fundamental constant ratio mq/ΛQCD.REFID="9789812838223_0043FN001">

  15. PENCEMARAN LOGAM BERAT MERKURI (Hg PADA AIRTANAH

    Directory of Open Access Journals (Sweden)

    Thomas Triadi Putranto

    2012-02-01

    Full Text Available The earth consists largely of water because the land area is smaller than the ocean. Human beings on this earthcan not escape the need for water. Water is the main requirement for the process of life on the earth.Relatively clean water that is coveted by men, whether for purposes of daily life, for industrial purposes, for thecleanliness of city sanitation, as well as for agricultural purposes and so forth. Heavy metal pollution is a veryserious issue to be handled, because of adverse environmental and ecosystem in general. Heavy metallic elementis the element which has a density of more than 5 gr/cm3. Hg has a density of 13.55 gr/cm3. Disaster is anoutbreak of Minamata mercury poisoning in people who eat fish contaminated by mercury in Minamata Japan,and this event is known as Minamata Disease. Efforts to tackle the heavy metal pollution can actually be doneusing a chemical process or by microorganism such as microbes and bacteria.

  16. Landfill Mining - Wet mechanical treatment of fine MSW with a wet jigger.

    Science.gov (United States)

    Wanka, Sebastian; Münnich, Kai; Fricke, Klaus

    2017-01-01

    The motives for landfill mining are various. In the last couple of years Enhanced Landfill Mining (ELFM) has become increasingly important in academic discourse and practical implementation. The main goal of ELFM is to recover as much material as possible from deposited municipal solid waste (MSW). In most of the projects carried out so far, the main focus has been set on coarse materials such as plastics, woods, papers and metals. These fractions can be separated easily by sieving in combination with magnetic separation. In these projects most of the fine materials, which might represent as much as 60-70% of the total mass of the landfill body, had to be deposited again. A further treatment aiming at reducing the masses of these fine materials, which are still a conglomerate of soil, calorific fractions, metals, minerals and residues, usually did not take place. One topic in the framework of the landfill mining project TÖNSLM, in addition to the separation of the calorific fraction and metals has been the treatment of fine materials with the goal to re-use these e.g. for construction purposes. This paper shows the results obtained after the wet mechanical treatment of fine MSW 10-60mm with a wet jigger. The physical principle of this process is the separation of the mass flux due to the different densities of the waste constituents. As a result, three main waste fluxes are obtained: Dense inert and dense fine fraction with a high content of minerals and a lightweight fraction with a high calorific value between 16 and 20MJ/kg. An additional positive effect of wet mechanical treatment is the removal of the finest particles from the surface of the waste material, thus increasing the quality of the generated waste fluxes. The mass fluxes of the different fractions and their qualities as well as possible recovery paths are described below. An economical and ecological consideration of the treatment of the fine materials does not take place within the framework of

  17. Hg-coordination studies of oligopeptides containing cysteine, histidine and tyrosine by $^{199m}$Hg-TDPAC

    CERN Document Server

    Ctortecka, B; Mallion, S; Butz, T; Hoffmann, R

    1999-01-01

    In order to study the interaction of histidine- and tyrosine- containing peptide chains with Hg(II), the nuclear quadrupole interaction (NQI) of /sup 199m/Hg in the Hg complexes of the oligopeptides alanyl-alanyl-histidyl-alanyl-alanine-amid (AAHAA-NH /sub 2/) and alanyl-alanyl-tyrosyl-alanyl-alanine-amid (AAYAA-NH/sub 2/) was determined by time differential perturbed angular correlation and is compared with previous data on alanyl-alanyl-cysteyl-alanyl- alanyl (AACAA-OH). The /sup 199m/Hg-NQIs depend on the oligopeptide to Hg(II) stoichiometry and indicate that two-fold and four-fold coordinations occur for the bound Hg(II). (12 refs).

  18. METALS DEPOSITS

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    <正>20070291 Gong Ping (Northern Fujian Geological Party, Shaozou 354000) Discussion on Geological Characteristics and Control Factors of the Shimen Au-polymetallic Deposit in Zhenghe County, Fujian Province (Geology of Fujian, ISSN1001-3970, CN38-1080/P, 25(1), 2006, p.18-24, 2 illus., 2 tables, 1 ref.) Key words: gold deposits, polymetallic deposits, Fujian Province

  19. Wet Work and Barrier Function.

    Science.gov (United States)

    Fartasch, Manigé

    2016-01-01

    Wet work defined as unprotected exposure to humid environments/water; high frequencies of hand washing procedures or prolonged glove occlusion is believed to cause irritant contact dermatitis in a variety of occupations. This review considers the recent studies on wet-work exposure and focuses on its influence on barrier function. There are different methods to study the effect of wet work on barrier function. On the one hand, occupational cohorts at risk can be monitored prospectively by skin bioengineering technology and clinical visual scoring systems; on the other hand, experimental test procedures with defined application of water, occlusion and detergents are performed in healthy volunteers. Both epidemiological studies and the results of experimental procedures are compared and discussed. A variety of epidemiological studies analyze occupational cohorts at risk. The measurement of transepidermal water loss, an indicator of the integrity of the epidermal barrier, and clinical inspection of the skin have shown that especially the frequencies of hand washing and water contact/contact to aqueous mixtures seem to be the main factors for the occurrence of barrier alterations. On the other hand, in a single cross-sectional study, prolonged glove wearing (e.g. occlusion for 6 h per shift in clean-room workers) without exposure to additional hazardous substances seemed not to affect the skin negatively. But regarding the effect of occlusion, there is experimental evidence that previously occluded skin challenged with sodium lauryl sulfate leads to an increased susceptibility to the irritant with an aggravation of the irritant reaction. These findings might have relevance for the real-life situation in so far as after occupational glove wearing, the skin is more susceptible to potential hazards to the skin even during leisure hours.

  20. Wetting properties of nanostructured surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Ramos-Canut, S. [Laboratoire de Physique de la Matiere Condensee et Nanostructures (UMR CNRS 5586), Universite Claude Bernard Lyon 1, 69622 Villeurbanne Cedex (France)]. E-mail: ramos@lpmcn.univ-lyon1.fr

    2006-04-15

    Swift heavy ion irradiation is a powerful tool to tailor surfaces under controlled conditions at a nanometric scale. The growing importance of nanostructured surfaces for a wide variety of applications and fundamental investigations is now well established. In this paper I will mainly discuss the interest of such surfaces for investigations concerning solid-liquid interfaces. The role played by topographical defects on wetting properties of solid surfaces, and both the dissipative and the confinement effects on the interface will be demonstrated by simple examples.

  1. Single-metalloprotein wet biotransistor

    Science.gov (United States)

    Alessandrini, Andrea; Salerno, Marco; Frabboni, Stefano; Facci, Paolo

    2005-03-01

    Metalloproteins are redox molecules naturally shuttling electrons with high efficiency between molecular partners. As such, they are candidates of choice for bioelectronics. In this work, we have used bacterial metalloprotein azurin, hosted in a nanometer gap between two electrically biased gold electrodes, to demonstrate an electrochemically gated single-molecule transistor operating in an aqueous environment. Gold-chemisorbed azurin shows peaks in tunneling current upon changing electrode potential and a related variation in tunneling barrier transparency which can be exploited to switch an electron current through it. These results suggest the wet approach to molecular electronics as a viable method for exploiting electron transfer of highly specialized biomolecules.

  2. Isotope geochemistry of mercury in source rocks, mineral deposits and spring deposits of the California Coast Ranges, USA

    Science.gov (United States)

    Smith, Christopher N.; Kesler, Stephen E.; Blum, Joel D.; Rytuba, James J.

    2008-05-01

    We present here the first study of the isotopic composition of mercury in rocks, ore deposits, and active spring deposits from the California Coast Ranges, a part of Earth's crust with unusually extensive evidence of mercury mobility and enrichment. The Franciscan Complex and Great Valley Sequence, which form the bedrock in the California Coast Ranges, are intruded and overlain by Tertiary volcanic rocks including the Clear Lake Volcanic Sequence. These rocks contain two types of mercury deposits, hot-spring deposits that form at shallow depths (geothermal areas continue to precipitate Hg and Au and are modern analogues to the fossil hydrothermal systems preserved in the ore deposits. The Franciscan Complex and Great Valley Sequence contain clastic sedimentary rocks with higher concentrations of mercury than volcanic rocks of the Clear Lake Volcanic Field. Mean mercury isotopic compositions ( δ202Hg) for all three rock units are similar, although the range of values in Franciscan Complex rocks is greater than in either Great Valley or Clear Lake rocks. Hot spring and silica-carbonate mercury deposits have similar average mercury isotopic compositions that are indistinguishable from averages for the three rock units, although δ202Hg values for the mercury deposits have a greater variance than the country rocks. Precipitates from spring and geothermal waters in the area have similarly large variance and a mean δ202Hg value that is significantly lower than the ore deposits and rocks. These observations indicate that there is little or no isotopic fractionation (< ± 0.5‰) during release of mercury from its source rocks into hydrothermal solutions. Isotopic fractionation does appear to take place during transport and concentration of mercury in deposits, however, especially in their uppermost parts. Boiling of hydrothermal fluids, separation of a mercury-bearing CO 2 vapor or reduction and volatilization of Hg (0) in the near-surface environment are likely the

  3. Real-time control of HgCdTe growth by organometallic vapor phase epitaxy using spectroscopic ellipsometry

    Science.gov (United States)

    Murthy, Srikanteswara Dakshina; Bhat, Ishwara; Johs, Blaine; Pittal, Shakil; He, Ping

    1995-09-01

    The use of spectroscopic ellipsometry for monitoring the vapor phase epitaxial growth of mercury cadmium telluride (Hg1-xCdxTe) in real-time is demonstrated. The ellipsometer is used to perform system identification of the chemical vapor deposition reactor used for the growth of CdTe and to measure the response of the reactor to different growth conditions. The dynamic behavior of the reactor is also studied by evaluating the gas transport delay. The optical constants of Hg1-xCdxTe are determined at the growth temperature for different compositions. In-situ real-time composition control is performed during the growth of Hg1-xCdxTe. The required target compositions are attained by the ellipsometer and appropriate corrections are also made by the controller when a noise input in the form of a temperature variation is introduced.

  4. Analysis of IMP-grown Cd sub x Hg sub 1-x Te using helium ion RBS

    Energy Technology Data Exchange (ETDEWEB)

    Avery, A.J.; Diskett, D.J. (Royal Military Coll. of Science, Shrivenham, Swindon (United Kingdom)); Gough, J.S.; Young, M.L. (Royal Signals and Radar Establishment, Malvern (United Kingdom))

    1992-02-01

    Epitaxial layers of Cd{sub x}Hg{sub 1-x}Te may be grown by the IMP (interdiffused multilayer process) technique in which alternate layers of CdTe and HgTe are deposited by metalorganic vapour phase epitaxy and interdiffused at the growth temperature. The infrared optical properties of the layers are critically dependent upon the value of x which may be tailored by controlling the relative thickness of the CdTe and HgTe sublayers. This paper describes the application of helium ion RBS to the study of the completeness of interdiffusion between sublayers and the application of channelling to the study of their crystalline quality. (orig.).

  5. SO2/Hg removal from flue gas by dry FGD

    Institute of Scientific and Technical Information of China (English)

    Wang Fan; Wang Hongmei; Zhang Fan; Zhu Jinwei; Tian Gang; Liu Yu; Mao Jixian

    2012-01-01

    To study the mechanism of SO2 and Hg removal from flue gas,an experimental packed bed reactor was designed to simulate the dry FGD,where a mixture of lime and fly ash in ratio 1∶3 w/w was used as the SO2 and Hg sorbent,and steam at temperature of 100 ℃ was applied for activation of the sorbent,while the activation time set to 20 min.The experimental factors including the SO2/Hg sorbent characteristics,50% breakthrough time for SO2/Hg removal,sorbent packed bed depth and reaction temperature were investigated.The experimental results show that after steam activation,the BET specific surface area and specific pore volume increased from 37.8 to 45.5 m2/g and from 0.42 to 0.51 cm3/g,respectively.With activation of the sorbent by steam,the 50% breakthrough times of SO2 and Hg removal increased from 34 to 42 min and from 23 to 45 min,respectively.When the packed bed depth was increased from 5 to 25 mm,the 50% breakthrough times for Hg and SO2 removal increased from 12 to 52 min and from 6 to 47 min,respectively.With the increase of the reaction temperature,the 50% breakthrough of SO2/Hg removal decreased accordingly.Steam activation can efficiently improve SO2/Hg removal simultaneously.

  6. 中亚热带典型林分不同层次氮硫湿沉降动态变化%Dynamics of Nitrogen and Sulfur Wet Deposition in Typical Forest Stand at Different Spatial Levels in Simian Mountain, Mid-subtropical Region

    Institute of Scientific and Technical Information of China (English)

    孙涛; 马明; 王定勇; 黄礼昕

    2014-01-01

    基于野外定点监测的方法,于2012年9月~2013年8月对四面山常绿阔叶林大气降水、穿透水、枯透水、土壤渗滤液进行了持续1 a 的氮、硫湿沉降动态变化的研究.结果表明:四面山大气降水全年 pH 平均值为4.89,最大值为5.14,大气降水明显偏酸性;土壤层和林冠层能使降雨的 pH 值有所升高,其中土壤层对 pH 值的调升幅度最大,其次为森林冠层;森林冠层对 NO -3、 NO -2、 SO2-4有一定的吸附净化作用,平均截留率分别为56.68%、45.84%、35.51%;研究结果也表明:枯枝落叶的降解是导致各离子质量浓度在枯透水中增加的原因;森林土壤能够吸附中和 NO -3、 SO2-4、 NH +4,释放出 NO -2.中亚热带常绿阔叶林生态系统对大气降水中 NO -3、 NO -2、 NH +4、 SO2-4的总截留率分别为92.86%、57.86%、87.24%、87.25%,对酸性降雨有一定的缓冲作用.%In order to investigate the dynamics of nitrogen and sulfur wet deposition in subtropical forest ecosystem, one typical forest stand, evergreen broad-leaved forest, at Simian Mountain located in Chongqing was selected in this research. Based on field monitoring, effects of precipitation, throughfall, litterfall, and groundwater runoff of the typical forest stand on the quality of water of Simian Mountain were investigated from September 2012 to August 2013. Results showed that the rainfall of Simian Mountain was apparently acidic, with average pH of 4. 89 and maximum pH of 5. 14. The soil, canopies and trunks could increase pH of precipitation, with soils having the maximum increment, followed by the forest canopy. Forest canopy had the function of adsorption and purification of NO -3 , NO -2 and SO2 -4 , and the average entrapment rate was 56. 68% , 45. 84% and 35. 51% , respectively. Moreover, the degradation of litter was probably the main reason for the increase of ion concentrations in the surface litter water. Forest soils could absorb and

  7. Mold management of wetted carpet.

    Science.gov (United States)

    Ong, Kee-Hean; Dixit, Anupma; Lewis, Roger D; MacDonald Perkins, Maureen; Backer, Denis; Condoor, Sridhar; Emo, Brett; Yang, Mingan

    2014-01-01

    This study evaluated the growth and removal of fungi on wetted carpet using newly designed technologies that rely on physical principles of steam, heat, and fluid flow. Sixty samples of carpet were embedded with heat-treated house dust, followed by embedding, wearing with a hexapod, and wetting. Samples were inoculated using a liquid suspension of Cladosporium sphaerospermum prior to placement over a water-saturated foam pad. Incubation times were 24 hr, 7 days, and 30 days. Cleaning was performed using three methods; high-flow hot water extraction, hot water and detergent, and steam. Fungal loading increased from approximately 1500 colony forming units per area (CFU/cm(2)) in 24 hr to a maximum of approximately 10,200 CFU/cm(2) after 7 days with a slight decline to 9700 CFU/cm(2) after 30 days incubation. Statistically significant differences were found among all three methods for removal of fungi for all three time periods (p Steam-vapor was significantly better than the alternative methods (p steam has a consistent fungal removal rate, the detergent and high-flow, hot water methods decline in efficiency with increasing incubation time.

  8. Elucidating the mysteries of wetting.

    Energy Technology Data Exchange (ETDEWEB)

    Webb, Edmund Blackburn, III (,; ); Bourdon, Christopher Jay; Grillet, Anne Mary; Sackinger, Philip A.; Grest, Gary Stephen; Emerson, John Allen; Ash, Benjamin Jesse; Heine, David R.; Brooks, Carlton, F.; Gorby, Allen D.

    2005-11-01

    Nearly every manufacturing and many technologies central to Sandia's business involve physical processes controlled by interfacial wetting. Interfacial forces, e.g. conjoining/disjoining pressure, electrostatics, and capillary condensation, are ubiquitous and can surpass and even dominate bulk inertial or viscous effects on a continuum level. Moreover, the statics and dynamics of three-phase contact lines exhibit a wide range of complex behavior, such as contact angle hysteresis due to surface roughness, surface reaction, or compositional heterogeneities. These thermodynamically and kinetically driven interactions are essential to the development of new materials and processes. A detailed understanding was developed for the factors controlling wettability in multicomponent systems from computational modeling tools, and experimental diagnostics for systems, and processes dominated by interfacial effects. Wettability probed by dynamic advancing and receding contact angle measurements, ellipsometry, and direct determination of the capillary and disjoining forces. Molecular scale experiments determined the relationships between the fundamental interactions between molecular species and with the substrate. Atomistic simulations studied the equilibrium concentration profiles near the solid and vapor interfaces and tested the basic assumptions used in the continuum approaches. These simulations provide guidance in developing constitutive equations, which more accurately take into account the effects of surface induced phase separation and concentration gradients near the three-phase contact line. The development of these accurate models for dynamic multicomponent wetting allows improvement in science based engineering of manufacturing processes previously developed through costly trial and error by varying material formulation and geometry modification.

  9. Net deposition of mercury to the Antarctic Plateau enhanced by sea salt.

    Science.gov (United States)

    Han, Yeongcheol; Huh, Youngsook; Hur, Soon Do; Hong, Sungmin; Chung, Ji Woong; Motoyama, Hideaki

    2017-04-01

    Photochemically driven mercury (Hg) exchange between the atmosphere and the Antarctic Plateau snowpack has been observed. An imbalance in bidirectional flux causes a fraction of Hg to remain in the snowpack perennially, but the factors that control the amount of Hg sequestered on the Antarctic Plateau are not fully understood. We analyzed sub-annual variations in total Hg (HgT) deposition to Dome Fuji over the period of 1986-2010 using cold vapor inductively coupled plasma mass spectrometry and compared concentrations with those of sea salt components (Na(+) and Cl(-)). HgT ranged from 0.12 to 5.19pgg(-1) (n=78) and was relatively high when the Na(+) concentrations were high in the same or underlying snow layers. A significant correlation (r=0.7) was found between the annual deposition fluxes of HgT and Na(+). Despite different origins and behavior of Hg and sea salt, the near-synchronous increases in the concentrations and correlation between the fluxes suggest that sea salt can intervene in the air-snow Hg exchange and promote the net deposition of Hg in the Antarctic Plateau.

  10. Aerial wetting contact angle measurement using confocal microscopy

    OpenAIRE

    Chesna, Jacob W.; Wiedmaier, Bob F.; Wang, Jinlin; Samara, Ayman; Leach, Richard K.; Her, Tsing-Hua; Smith, Stuart T.

    2016-01-01

    A method is presented in which the wetting contact angle of a sessile drop is acquired aerially using confocal techniques to measure the radius and the height of a droplet deposited on a planar surface. The repeatability of this method is typically less than 0.25°, and often less than 0.1°, for droplet diameters less than 1 mm. To evaluate accuracy of this method, an instrument uncertainty budget is developed, which predicts a combined uncertainty of 0.91° for a 1 mm diameter water droplet wi...

  11. Process of forming catalytic surfaces for wet oxidation reactions

    Science.gov (United States)

    Jagow, R. B. (Inventor)

    1977-01-01

    A wet oxidation process was developed for oxidizing waste materials, comprising dissolved ruthenium salt in a reactant feed stream containing the waste materials. The feed stream is introduced into a reactor, and the reactor contents are then raised to an elevated temperature to effect deposition of a catalytic surface of ruthenium black on the interior walls of the reactor. The feed stream is then maintained in the reactor for a period of time sufficient to effect at least partial oxidation of the waste materials.

  12. Wetting and Non-Wetting Models of Black Carbon Activation

    Science.gov (United States)

    Henson, B. F.; Laura, S.

    2006-12-01

    We present the results of recent modeling studies on the activation of black carbon (BC) aerosol to form cloud condensation nuclei (CCN). We use a model of BC activation based on a general modification of the Koehler equation for insoluble activation in which we introduce a term based on the activity of water adsorbed on the particle surface. We parameterize the model using the free energy of adsorption, a parameter directly comparable to laboratory measurements of water adsorption on carbon. Although the model of the water- surface interaction is general, the form of the activation equation that results depends upon a further model of the distribution of water on the particle. One possible model involves the symmetric growth of a water shell around the isoluble particle core (wetting). This model predicts upper and lower bounding curves for the activation supersaturation given by the range of water interaction energies from hydrophobic to hydrophilic which are in agreement with a large body of recent activation data. The resulting activation diameters are from 3 to 10 times smaller than activation of soluble particles of identical dry diameter. Another possible model involves an exluded liquid droplet growing in contact with the particle (non-wetting). The geometry of this model much more resembles classic assumptions of heterogeneous nucleation theory. This model can yield extremely high activation supersaturation as a function of diameter, as has been observed in some experiments, and enables calculations in agreement with some of these results. We discuss these two geometrical models of water growth, the different behaviors predicted by the resulting activation equation, and the means to determine which model of growth is appropriate for a given BC particle characterized by either water interaction energy or morphology. These simple models enable an efficient and physically reasonable means to calculate the activation of BC aerosol to form CCN based upon a

  13. Tracing anthropogenic Hg and Pb input using stable Hg and Pb isotope ratios in sediments of the central Portuguese Margin

    NARCIS (Netherlands)

    Mil-Holmens, M.; Blum, J.; Canário, J.; Caetano, M.; Costa, A.M.; Lebreiro, S.M.; Trancoso, M.; Richter, T.O.; de Stigter, H.; Johnson, M.; Branco, V.; Cesário, R.; Mouro, F.; Mateus, M.; Boer, W.; Melo, Z.

    2013-01-01

    Three short marine sediment cores from the Cascais Submarine Canyon (CSC; cores 252-32 and 252-35) and the Estremadura Spur (core 252-16) on the central Portuguese Margin were analysed for Hg, Pb, Al, and Mn concentrations, and both Pb and Hg stable isotope compositions, in order to reconstruct tren

  14. Drop splashing is independent of substrate wetting

    CERN Document Server

    Latka, Andrzej; Nagel, Sidney R; de Pablo, Juan J

    2016-01-01

    A liquid drop impacting a dry solid surface with sufficient kinetic energy will splash, breaking apart into numerous secondary droplets. This phenomenon shows many similarities to forced wetting, including the entrainment of air at the contact line. Because of these similarities and the fact that forced wetting has been shown to depend on the wetting properties of the surface, existing theories predict splashing to depend on wetting properties as well. However, using high-speed interference imaging we observe that wetting properties have no effect on splashing for various liquid-surface combinations. Additionally, by fully resolving the Navier-Stokes equations at length and time scales inaccessible to experiments, we find that the shape and motion of the air-liquid interface at the contact line are independent of wettability. We use these findings to evaluate existing theories and to compare splashing with forced wetting.

  15. Estimates of Asian dust deposition over the Asian region by using ADAM2 in 2007.

    Science.gov (United States)

    Park, Soon-Ung; Choe, Anna; Park, Moon-Soo

    2010-05-01

    The Asian Dust Aerosol Model 2 (ADAM2) with the MM5 meteorological model has been employed to estimate the dust concentration, and wet and dry depositions of dust in the Asian region for the year of 2007. It is found that the model simulates quite reasonably the dust (PM(10)) concentrations both in the dust source region (100-110 degrees E and 37-43 degrees N) and the downstream region of Korea. The starting and ending times of most of dust events and their peak concentration occurring times are well simulated. The annual average dust (PM(10)) concentration near the surface is found to be 171microgm(-3) over the dust source area, 39microgm(-3) over the Yellow Sea, 25microgm(-3) over the Korean peninsula and 17microgm(-3) over the East Sea. It is also found that the annual total deposition of dust is about 118.1tkm(-2) (dry deposition, 101.4tkm(-2); wet deposition, 16.7tkm(-2)) in the dust source region, 19.0tkm(-2) (dry deposition, 7.8tkm(-2); wet deposition, 11.2tkm(-2)) in the Yellow Sea, 12.6tkm(-2) (dry deposition, 6.5tkm(-2); wet deposition, 6.1tkm(-2)) in the Korean peninsula and 10.7tkm(-2) (dry deposition, 2.1tkm(-2); wet deposition, 8.6tkm(-2)) in the East Sea. Their ratios of wet deposition to total deposition of dust in the respective regions are 14%, 59%, 48% and 80%. This clearly indicates that the main dust removal mechanism from the atmosphere is dry deposition over the source region whereas wet deposition predominates in the downstream region of the sea. The estimated dust deposition could adversely impact the eco-environmental system in the downstream regions of the dust source region significantly.

  16. Use of hg-electroplated-pt ultramicroelectrode for determining elemental sulphur in naphtha samples.

    Science.gov (United States)

    de Andrade, Carlos Eduardo; de Souza, Flávia C; Fernandes, Daniella R; Machado, Sérgio A S; D'Elia, Eliane

    2012-01-01

    This paper describes the applicability of a Hg-electroplated-Pt ultramicroelectrode in the quantification of elemental sulphur in naphtha samples by square-wave voltammetry. A reproducible deposition methodology was studied and is reported in this paper. This methodology is innovative and relies on the quality of the mercury stock solution to obtain reproducible surfaces required for the analytical methodology. All analyses were performed using a Hg-electroplated-Pt ultramicroelectrode (Hg-Pt UME) due to the low sensibility of such devices to ohmic drops in resistive solutions. The responses of the peak areas in voltammetric experiments were linear in all of the range studied. The method developed here is accurate and reproducible, with a detection limit of 0.010 mg L(-1) and a good recovery range for both standard solutions of elemental sulphur (85 to 99%) and real naphtha sample (79%). These results attest to the potential for the application of this electroanalytical methodology in determining elemental sulphur in naphtha samples containing mercaptans and disulphides.

  17. Use of Hg-Electroplated-Pt Ultramicroelectrode for Determining Elemental Sulphur in Naphtha Samples

    Directory of Open Access Journals (Sweden)

    Carlos Eduardo de Andrade

    2012-01-01

    Full Text Available This paper describes the applicability of a Hg-electroplated-Pt ultramicroelectrode in the quantification of elemental sulphur in naphtha samples by square-wave voltammetry. A reproducible deposition methodology was studied and is reported in this paper. This methodology is innovative and relies on the quality of the mercury stock solution to obtain reproducible surfaces required for the analytical methodology. All analyses were performed using a Hg-electroplated-Pt ultramicroelectrode (Hg-Pt UME due to the low sensibility of such devices to ohmic drops in resistive solutions. The responses of the peak areas in voltammetric experiments were linear in all of the range studied. The method developed here is accurate and reproducible, with a detection limit of 0.010 mg L−1 and a good recovery range for both standard solutions of elemental sulphur (85 to 99% and real naphtha sample (79%. These results attest to the potential for the application of this electroanalytical methodology in determining elemental sulphur in naphtha samples containing mercaptans and disulphides.

  18. Optimized wet clutches:simulation and tribotesting

    OpenAIRE

    2006-01-01

    Wet clutches are used in a variety of different machinery. Wet clutches and brakes are frequently used to distribute torque in vehicle drive-trains. The clutches can be located in e.g. automatic transmissions or limited slip differentials. Their frictional behavior is of great importance for the overall vehicle behavior and has to be thoroughly investigated when designing new wet clutch applications. Frictional behavior is normally investigated in test rigs where complete friction discs are t...

  19. The Wet-Dog Shake

    CERN Document Server

    Dickerson, Andrew; Bauman, Jay; Chang, Young-Hui; Hu, David

    2010-01-01

    The drying of wet fur is a critical to mammalian heat regulation. In this fluid dynamics video, we show a sequence of films demonstrating how hirsute animals to rapidly oscillate their bodies to shed water droplets, nature's analogy to the spin cycle of a washing machine. High-speed videography and fur-particle tracking is employed to determine the angular position of the animal's shoulder skin as a function of time. X-ray cinematography is used to track the motion of the skeleton. We determine conditions for drop ejection by considering the balance of surface tension and centripetal forces on drops adhering to the animal. Particular attention is paid to rationalizing the relationship between animal size and oscillation frequency required to self-dry.

  20. Externally Wetted Ionic Liquid Thruster

    Science.gov (United States)

    Lozano, P.; Martinez-Sanchez, M.; Lopez-Urdiales, J. M.

    2004-10-01

    This paper presents initial developments of an electric propulsion system based on ionic liquid ion sources (ILIS). Propellants are ionic liquids, which are organic salts with two important characteristics; they remain in the liquid state at room temperature and have negligible vapor pressure, thus allowing their use in vacuum. The working principles of ILIS are similar to those of liquid metal ion sources (LMIS), in which a Taylor cone is electrostatically formed at the tip of an externally wetted needle while ions are emitted directly from its apex. ILIS have the advantage of being able to produce negative ions that have similar masses than their positive counterparts with similar current levels. This opens up the possibility of achieving plume electrical neutrality without electron emitters. The possible multiplexing of these emitters is discussed in terms of achievable thrust density for applications other than micro-propulsion.

  1. Wet granular walkers and climbers

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Z S; Steinberger, A; Seemann, R; Herminghaus, S, E-mail: audrey.steinberger@ens-lyon.fr [Max Planck Institute for Dynamics and Self-Organization, Bunsenstrasse 10, D-37073 Goettingen (Germany)

    2011-05-15

    Mechanisms of locomotion in microscopic systems are of great interest not only for technological applications but also for the sake of understanding, and potentially harnessing, processes far from thermal equilibrium. Downscaling is a particular challenge and has led to a number of interesting concepts, including thermal ratchet systems and asymmetric swimmers. Here we present a granular ratchet system employing a particularly robust mechanism that can be implemented in various settings. The system consists of wetted spheres of different sizes that adhere to each other, and are subject to a symmetric oscillating, zero average external force field. An inherent asymmetry in the mutual force network leads to force rectification and hence to locomotion. We present a simple model that accounts for the observed behaviour, underscores its robustness and suggests a potential scalability of the concept.

  2. A 6,000-years record of atmospheric mercury accumulation in the high Arctic from peat deposits on Bathurst Island, Nunavut, Canada

    DEFF Research Database (Denmark)

    Givelet, N.; Roos-Barraclough, F.; Goodsite, M. E.

    2003-01-01

    There is a growing interest in the atmospheric transport, deposition, and accumulation of anthropogenic Hg in the Arctic. To quantify the impact of industrial Hg emissions, the natural rate of atmospheric Hg accumulation must be known. Mercury concentration measurements and age dating of peat fro...

  3. Anthropogenic mercury deposition in Flin Flon Manitoba and the Experimental Lakes Area Ontario (Canada): A multi-lake sediment core reconstruction.

    Science.gov (United States)

    Wiklund, Johan A; Kirk, Jane L; Muir, Derek C G; Evans, Marlene; Yang, Fan; Keating, Jonathan; Parsons, Matthew T

    2017-02-18

    High-resolution records of anthropogenic mercury (Hg) deposition were constructed from 9 lakes located 5-75km from the Flin Flon, Manitoba smelter (formerly one of North America's largest atmospheric Hg point sources) and 5 lakes in Experimental Lakes Area (ELA), Ontario; a region remote from major Hg point sources. Anthropogenic Hg deposition, as both a flux and inventory, was determined after accounting for lake-specific natural Hg background concentrations, changes in sedimentation and sediment focusing. Results show that records of anthropogenic flux and inventory of Hg were remarkably consistent among the ELA lakes, but varied by 2 orders of magnitude among Flin Flon lakes. The relation between Hg inventories (normalized for prevailing wind direction) and distance from the smelter was used to estimate the total Hg fallout within a 50km radius in 5year time-steps, thus providing a quantitative spatial-temporal Hg depositional history for the Flin Flon region. The same relation solved for 8 cardinal directions weighted by the inverse of the previously applied wind direction normalization generates a map of Hg inventory and deposition on the landscape (Supplementary video). This novel application of sediment core data constructs a landscape model and allows for a visualization of contaminant deposition with respect to a point major source in both space and time. The propensity for Hg to undergo long-range, even global transport explains why Hg deposition within 50km of Flin Flon was ~11% of estimated releases. That is until smelter releases were reduced >10-fold (post-2000), after which observed deposition exceeded smelter releases, suggesting landscape re-emission/remobilization of legacy Hg is a major ongoing regional source of Hg.

  4. Carbon nanotube fiber spun from wetted ribbon

    Science.gov (United States)

    Zhu, Yuntian T; Arendt, Paul; Zhang, Xiefei; Li, Qingwen; Fu, Lei; Zheng, Lianxi

    2014-04-29

    A fiber of carbon nanotubes was prepared by a wet-spinning method involving drawing carbon nanotubes away from a substantially aligned, supported array of carbon nanotubes to form a ribbon, wetting the ribbon with a liquid, and spinning a fiber from the wetted ribbon. The liquid can be a polymer solution and after forming the fiber, the polymer can be cured. The resulting fiber has a higher tensile strength and higher conductivity compared to dry-spun fibers and to wet-spun fibers prepared by other methods.

  5. Effects of wet-cupping on blood pressure in hypertensive patients:a randomized controlled trial

    Institute of Scientific and Technical Information of China (English)

    Nouran A Aleyeidi; Khaled S Aseri; Shadia M Matbouli; Albaraa A Sulaiamani; Sumayyah A Kobeisy

    2015-01-01

    BACKGROUND: Although cupping remains a popular treatment modality worldwide, its efficacy for most diseases, including hypertension, has not been scientifical y evaluated. OBJECTIVE: We aimed to determine the efficacy of wet-cupping for high blood pressure, and the incidence of the procedure’s side effects in the intervention group. DESIGN, SETTING, PARTICIPANTS AND INTERVENTIONS: This is a randomized control ed trial conducted in the General Practice Department at King Abdulaziz University Hospital, Jeddah, Saudi Arabia, between May 2013 and February 2014. There were two groups (40 participants each):intervention group undergoing wet-cupping (hijama) in addition to conventional hypertension treatment, and a control group undergoing only conventional hypertension treatment. Three wet-cupping sessions were performed every other day. MAIN OUTCOME MEASURE: The mean systolic and diastolic blood pressures were measured using a validated automatic sphygmomanometer. The fol ow-up period was 8 weeks. RESULTS: Wet-cupping provided an immediate reduction of systolic blood pressure. After 4 weeks of fol ow-up, the mean systolic blood pressure in the intervention group was 8.4 mmHg less than in the control group (P = 0.046). After 8 weeks, there were no significant differences in blood pressures between the intervention and control groups. In this study, wet-cupping did not result in any serious side effects. CONCLUSION: Wet-cupping therapy is effective for reducing systolic blood pressure in hypertensive patients for up to 4 weeks, without serious side effects. Wet-cupping should be considered as a complementary hypertension treatment, and further studies are needed. TRIAL REGISTRATION: ClinicalTrials.gov Identifier NCT01987583.

  6. Time-varying wetting behavior on copper wafer treated by wet-etching

    Energy Technology Data Exchange (ETDEWEB)

    Tu, Sheng-Hung; Wu, Chuan-Chang [Department of Chemical and Materials Engineering, National Central University, Jhongli 320, Taiwan, ROC (China); Wu, Hsing-Chen [Advanced Technology Materials Inc, Hsinchu 310, Taiwan, ROC (China); Cheng, Shao-Liang [Department of Chemical and Materials Engineering, National Central University, Jhongli 320, Taiwan, ROC (China); Sheng, Yu-Jane, E-mail: yjsheng@ntu.edu.tw [Department of Chemical Engineering, National Taiwan University, Taipei 106, Taiwan, ROC (China); Tsao, Heng-Kwong, E-mail: hktsao@cc.ncu.edu.tw [Department of Chemical and Materials Engineering, National Central University, Jhongli 320, Taiwan, ROC (China)

    2015-06-30

    Graphical abstract: - Highlights: • A thin oxide layer always remains on surfaces of Cu wafers after aqueous etching. • A pure Cu wafer is obtained by the HAc treatment and the water CA is about 45°. • The oxide layer and CA grow with time after the Cu wafer is exposed to air. • Surface roughness and hydrophobicity of pure Cu wafers grow rapidly in vacuum. - Abstract: The wet cleaning process in semiconductor fabrication often involves the immersion of the copper wafer into etching solutions and thereby its surface properties are significantly altered. The wetting behavior of a copper film deposited on silicon wafer is investigated after a short dip in various etching solutions. The etchants include glacial acetic acid and dilute solutions of nitric acid, hydrofluoric acid, and tetramethylammonium hydroxide. It was found that in most cases a thin oxide layer still remains on the surface of as-received Cu wafers when they are subject to etching treatments. However, a pure Cu wafer can be obtained by the glacial acetic acid treatment and its water contact angle (CA) is about 45°. As the pure Cu wafer is placed in the ambient condition, the oxide thickness grows rapidly to the range of 10–20 Å within 3 h and the CA on the hydrophilic surface also rises. In the vacuum, it is surprising to find that the CA and surface roughness of the pure Cu wafer can grow significantly. These interesting results may be attributed to the rearrangement of surface Cu atoms to reduce the surface free energy.

  7. Field Testing of a Wet FGD Additive for Enhanced Mercury Control - Pilot-Scale Test Results

    Energy Technology Data Exchange (ETDEWEB)

    Gary M. Blythe

    2006-03-01

    This Topical Report summarizes progress on Cooperative Agreement DE-FC26-04NT42309, ''Field Testing of a Wet FGD Additive.'' The objective of the project is to demonstrate the use of a flue gas desulfurization (FGD) additive, Degussa Corporation's TMT-15, to prevent the reemissions of elemental mercury (Hg{sup 0}) in flue gas exiting wet FGD systems on coal-fired boilers. Furthermore, the project intends to demonstrate that the additive can be used to precipitate most of the mercury (Hg) removed in the wet FGD system as a fine TMT salt that can be separated from the FGD liquor and bulk solid byproducts for separate disposal. The project will conduct pilot and full-scale tests of the TMT-15 additive in wet FGD absorbers. The tests are intended to determine required additive dosage requirements to prevent Hg{sup 0} reemissions and to separate mercury from the normal FGD byproducts for three coal types: Texas lignite/Power River Basin (PRB) coal blend, high-sulfur Eastern bituminous coal, and low-sulfur Eastern bituminous coal. The project team consists of URS Group, Inc., EPRI, TXU Generation Company LP, Southern Company, and Degussa Corporation. TXU Generation has provided the Texas lignite/PRB co-fired test site for pilot FGD tests, Monticello Steam Electric Station Unit 3. Southern Company is providing the low-sulfur Eastern bituminous coal host site for wet scrubbing tests, as well as the pilot and full-scale jet bubbling reactor (JBR) FGD systems to be tested. A third utility, to be named later, will provide the high-sulfur Eastern bituminous coal full-scale FGD test site. Degussa Corporation is providing the TMT-15 additive and technical support to the test program. The project is being conducted in six tasks. Of the six project tasks, Task 1 involves project planning and Task 6 involves management and reporting. The other four tasks involve field testing on FGD systems, either at pilot or full scale. The four tasks include: Task 2

  8. An investigation for the HgCdTe cleaning process

    Science.gov (United States)

    Lan, Tian-Yi; Wang, Nili; Zhao, Shuiping; Liu, Shi-Jia; Li, Xiang-Yang

    2014-11-01

    A new cleaning process for HgCdTe was designed - which used the improved SC-1,SC-2 and Br2- C2H5OH solutions as the main cleaning fluid and applied mega sound waves in the cleaning process. By analyzing the test results carried out on the HgCdTe surface, it was found that the material of HgCdTe for the application of new cleaning process was better than the one for the application of conventional cleaning process in the minority carrier lifetime, residual organic contamination, responsivity and specific detectivity.

  9. Doping and Diffusion in HgCdTe

    Science.gov (United States)

    1991-01-28

    In’i, -InT. Te - 1.8 ( - 3 .5 )h ( + 2.9 - 6/) TeT1’- Tej . 4 Hg rich HgCdTe Hg - 1.8 + 1.2 + 1.4 - 2p H - ’g, - H g j.. ’TI - tetrahedral position...A. Anderson, Appl. Phys. Lett. 53, 11.81 (1988). B. D. Patterson, Rev. Mod. Phys. 60, 69 (1988). 60 V. A. Singh , C. Weigel, J. W. Corbett, and L. M

  10. Uncertainty associated with convective wet removal of entrained aerosols in a global climate model

    Science.gov (United States)

    Croft, B.; Pierce, J. R.; Martin, R. V.; Hoose, C.; Lohmann, U.

    2012-11-01

    The uncertainties associated with the wet removal of aerosols entrained above convective cloud bases are investigated in a global aerosol-climate model (ECHAM5-HAM) under a set of limiting assumptions for the wet removal of the entrained aerosols. The limiting assumptions for the wet removal of entrained aerosols are negligible scavenging and vigorous scavenging (either through activation, with size-dependent impaction scavenging, or with the prescribed fractions of the standard model). To facilitate this process-based study, an explicit representation of cloud-droplet-borne and ice-crystal-borne aerosol mass and number, for the purpose of wet removal, is introduced into the ECHAM5-HAM model. This replaces and is compared with the prescribed cloud-droplet-borne and ice-crystal-borne aerosol fraction scavenging scheme of the standard model. A 20% to 35% uncertainty in simulated global, annual mean aerosol mass burdens and optical depth (AOD) is attributed to different assumptions for the wet removal of aerosols entrained above convective cloud bases. Assumptions about the removal of aerosols entrained above convective cloud bases control modeled upper tropospheric aerosol concentrations by as much as one order of magnitude. Simulated aerosols entrained above convective cloud bases contribute 20% to 50% of modeled global, annual mean aerosol mass convective wet deposition (about 5% to 10% of the total dry and wet deposition), depending on the aerosol species, when including wet scavenging of those entrained aerosols (either by activation, size-dependent impaction, or with the prescribed fraction scheme). Among the simulations, the prescribed fraction and size-dependent impaction schemes yield the largest global, annual mean aerosol mass convective wet deposition (by about two-fold). However, the prescribed fraction scheme has more vigorous convective mixed-phase wet removal (by two to five-fold relative to the size-dependent impaction scheme) since nearly all

  11. Quantifying atmospheric nitrogen deposition through a nationwide monitoring network across China

    Directory of Open Access Journals (Sweden)

    W. Xu

    2015-07-01

    Full Text Available Global reactive nitrogen (Nr deposition to terrestrial ecosystems has increased dramatically since the industrial revolution. This is especially true in recent decades in China due to continuous economic growth. However, there are no comprehensive reports of both measured dry and wet Nr deposition across China. We therefore conducted a multiple-year study during the period mainly from 2010 to 2014 to monitor atmospheric concentrations of five major Nr species of gaseous NH3, NO2 and HNO3, and inorganic nitrogen (NH4+ and NO3− in both particles and precipitation, based on a Nationwide Nitrogen Deposition Monitoring Network (NNDMN, covering 43 sites in China. Wet deposition fluxes of Nr species were measured directly; dry deposition fluxes were estimated using airborne concentration measurements and inferential models. Our observations reveal large spatial variations of atmospheric Nr concentrations and dry and wet Nr deposition. The annual average concentrations (1.3–47.0 μg N m−3 and dry plus wet deposition fluxes (2.9–75.2 kg N ha−1 yr−1 of inorganic Nr species ranked by region as North China > Southeast China > Southwest China > Northeast China > Northwest China > the Tibetan Plateau or by land use as urban > rural > background sites, reflecting the impact of anthropogenic Nr emission. Average dry and wet N deposition fluxes were 18.5 and 19.3 kg N ha−1 yr−1, respectively, across China, with reduced N deposition dominating both dry and wet deposition. Our results suggest atmospheric dry N deposition is equally important to wet N deposition at the national scale and both deposition forms should be included when considering the impacts of N deposition on environment and ecosystem health.

  12. HgI{sub 2} detector fabrication; Construccion de detectores de HgI{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, M.; Perez, J. M.

    1996-07-01

    The aim of the present work is to describe the steps followed to fabricate an ionizing radiation detector based on synthetic mercuric iodide monocrystal layers. Firstly, the crystalline orientation method has been describe, which is needed before the layer cutting perpendicularly to the (001) crystallographic. It is also defined the proceeding to crystal face finishing by a mechanical polishing and subsequent chemical etching. then, the metal electrode deposition and the view connection has been explained. Finally, the technique followed to encapsulate the detector with a polymeric thin film deposition has been described. (Author) 10 refs.

  13. Surface Modification of Textured Dielectrics and Their Wetting Behavior

    Science.gov (United States)

    Kumar, Vijay; Dhillon, Ajaypal Singh; Sharma, Niti Nipun

    2017-02-01

    Controlling the wettability on dielectric materials is a classical topic in surface engineering. Surface texturing and deposition of self-assembled monolayers (SAMs) are major approaches to achieve lower or higher water contact angle ( θ c) and thereby making surface less or more wettable (more hydrophobic). Dielectric surfaces wetting has been engineered by surface modification and has been shown to achieve θ c to a maximum of 120° ± 5°. Further improvement in θ c to an extent greater than 150° ± 5° is desired to render the surface superhydrophobic. We report in this work an achievement of θ c > 150° ± 5° by combining the plasma-treated surface and octadecyltrichlorosilane (OTS) SAMs deposition on dielectrics, and this had been shown on dielectric ranging from low- k to high- k values. The improvement in wetting behavior and quality of dielectric surface with monolayer on plasma-treated surfaces are (is) investigated and characterized using atomic-force microscope (AFM), scanning electron microscope (SEM), contact angle goniometer, and Raman spectroscopy and x-ray photoelectron spectroscopy (XPS) and are compared with untreated dielectric surface with OTS monolayers.

  14. Surface Modification of Textured Dielectrics and Their Wetting Behavior

    Science.gov (United States)

    Kumar, Vijay; Dhillon, Ajaypal Singh; Sharma, Niti Nipun

    2017-01-01

    Controlling the wettability on dielectric materials is a classical topic in surface engineering. Surface texturing and deposition of self-assembled monolayers (SAMs) are major approaches to achieve lower or higher water contact angle (θ c) and thereby making surface less or more wettable (more hydrophobic). Dielectric surfaces wetting has been engineered by surface modification and has been shown to achieve θ c to a maximum of 120° ± 5°. Further improvement in θ c to an extent greater than 150° ± 5° is desired to render the surface superhydrophobic. We report in this work an achievement of θ c > 150° ± 5° by combining the plasma-treated surface and octadecyltrichlorosilane (OTS) SAMs deposition on dielectrics, and this had been shown on dielectric ranging from low-k to high-k values. The improvement in wetting behavior and quality of dielectric surface with monolayer on plasma-treated surfaces are (is) investigated and characterized using atomic-force microscope (AFM), scanning electron microscope (SEM), contact angle goniometer, and Raman spectroscopy and x-ray photoelectron spectroscopy (XPS) and are compared with untreated dielectric surface with OTS monolayers.

  15. Aggressive media exposed differential pressure sensor with a deposited membrane

    DEFF Research Database (Denmark)

    Bouaidat, Salim; Eriksen, Gert Friis; Reus, Roger De

    2001-01-01

    A new piezoresistive differential pressure sensor design for harsh wet environments is presented. The sensor design is based on a deposited membrane, which is deposited on top of polysilicon interconnects and piezoresistors. Flat membrane surfaces are thereby achieved. This enables thin film...

  16. Uptake of HgCl{sub 2} and MeHgCl in an insect cell line (Aedes albopictus C6/36)

    Energy Technology Data Exchange (ETDEWEB)

    Braeckman, B.; Cornelis, R.; Rzeznik, U.; Raes, H. [Univ. of Ghent (Belgium)

    1998-10-01

    The authors studied the uptake mechanism of mercuric chloride (Hg) and methylmercuric chloride (MeHg) in Aedes albopictus C6/36 cells. The uptake kinetics, together with the effect of temperature and a metabolic inhibitor (2,4-dinitrophenol) on the mercury accumulation, were examined. Both amounts of internalized Hg and MeHg increased linearly with the extracellular concentration. Initially, the influx rate was high for both metal species but MeHg was found to accumulate seven times faster than Hg. At longer exposure times it leveled off for Hg, while for MeHg, the intracellular concentration decreased. Hg toxicity was not significantly influenced by elevated temperatures; in contrast there was a marked decrease of the LC{sub 50/24 h} value for MeHg. On the other hand, Hg accumulation was temperature dependent but MeHg was not. The different toxicity and uptake rate of both mercury compounds can be explained in terms of membrane permeability and target site. For Hg the main target seems to be the plasma membrane, while MeHg readily crosses this barrier and reacts with intracellular targets. 2,4-Dinitrophenol had no effect on the accumulation of Hg but that of MeHg was doubled.

  17. Results Of Hg Speciation Testing On DWPF SMECT-1, SMECT-3, And SMECT-5 Samples

    Energy Technology Data Exchange (ETDEWEB)

    Bannochie, C. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2016-01-07

    The Savannah River National Laboratory (SRNL) was tasked with preparing and shipping samples for Hg speciation by Eurofins Frontier Global Sciences, Inc. in Seattle, WA on behalf of the Savannah River Remediation (SRR) Mercury Task Team. The thirteenth shipment of samples was designated to include Defense Waste Processing Facility (DWPF) Slurry Mix Evaporator Condensate Tank (SMECT) from Sludge Receipt and Adjustment Tank (SRAT) Batch 736 and 738 samples. Triplicate samples of each material were prepared for this shipment. Each replicate was analyzed for seven Hg species: total Hg, total soluble (dissolved) Hg, elemental Hg [Hg(0)], ionic (inorganic) Hg [Hg(I) and Hg(II)], methyl Hg [CH3Hg-X, where X is a counter anion], ethyl Hg [CH3CH2-Hg-X, where X is a counter anion], and dimethyl Hg [(CH3)2Hg]. The difference between the total Hg and total soluble Hg measurements gives the particulate Hg concentration, i.e. Hg adsorbed to the surface of particulate matter in the sample but without resolution of the specific adsorbed species. The average concentrations of Hg species in the aqueous samples derived from Eurofins reported data corrected for dilutions performed by SRNL are tabulated.

  18. Quantum Calorimeters Based on HgCdTe Alloys Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA's next generation of x-ray observation missions require x-ray calorimeters with superior energy resolution. Semimetallic HgTe has already proven itself as an...

  19. Enrichment of Pb, Hg and Cr in cultured carp otolith

    African Journals Online (AJOL)

    AJL

    2012-01-26

    Jan 26, 2012 ... record the pollution condition at the sampling time. ... aquatic organisms are aquatic algae, zooplankton .... element cannot show that Hg concentration in otolith ..... from Atlantic croaker along an estuarine pollution gradient.

  20. Quantum Calorimeters Based on HgCdTe Alloys Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA's next generation of x-ray observation missions require x-ray calorimeters with superior energy resolution. Semimetallic HgTe has already proven itself as an...

  1. Properties of Light Hg, Pb and Po Isotopes

    CERN Document Server

    Muntian, I

    2003-01-01

    Quality of mass description for three different theoretical mass models is studied. Masses and deformations for Po, Pb and Hg isotopes are compared with experimental data. Gap in the proton single particle energy spectrum is discussed.

  2. Horizontal Branch stars as AmFm/HgMn stars

    CERN Document Server

    Michaud, G

    2008-01-01

    Recent observations and models for horizontal branch stars are briefly described and compared to models for AmFm stars. The limitations of those models are emphasized by a comparison to observations and models for HgMn stars.

  3. Interaction of Hg Atom with Bare Si(111) Surface

    Institute of Scientific and Technical Information of China (English)

    LIU Yong-Jun; LIU Ying

    2006-01-01

    To evaluate the interaction between Hg atom and bare Si(111) surface, three types of silicon cluster models of Si4H7, Si7H10 and Si16H20 together with their Hg complexes were studied by using hybrid (U)B3LYP density functional theory method. Optimized geometries and energies for Hg atom on different adsorption sites indicate that: 1) the binding energies at different adsorption sites are small (ranging from ~3 to 8 kJ/mol dependent on the adsorption sites), suggesting a weak interaction between Hg atom and silicon surface; 2) the most favorable adsorption site is the on top (T) site. By analyzing their natural bonding orbitals, the possible reason of this difference is suggested.

  4. 7 CFR 29.2570 - Wet (W).

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Wet (W). 29.2570 Section 29.2570 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2570 Wet (W). Any sound tobacco...

  5. 7 CFR 29.3567 - Wet (W).

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Wet (W). 29.3567 Section 29.3567 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Type 95) § 29.3567 Wet (W). Any sound tobacco containing excessive moisture to the extent that it is...

  6. 7 CFR 29.2316 - Wet (W).

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Wet (W). 29.2316 Section 29.2316 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... INSPECTION Standards Official Standard Grades for Virginia Fire-Cured Tobacco (u.s. Type 21) § 29.2316 Wet...

  7. 7 CFR 29.3077 - Wet (W).

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Wet (W). 29.3077 Section 29.3077 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Wet (W). Any sound tobacco containing excessive moisture to the extent that it is in an unsafe...

  8. 7 CFR 29.1083 - Wet (W).

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Wet (W). 29.1083 Section 29.1083 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Type 92) § 29.1083 Wet (W). Any sound tobacco containing excessive moisture to the extent that it is...

  9. Characteristics of wet work in nurses

    NARCIS (Netherlands)

    Jungbauer, FHW; Steenstra, FB; Groothoff, JW; Coenraads, PJ

    Background objectives: Nursing is known for its high prevalence of hand dermatitis, mainly caused by the intense exposure to wet work in nursing activities. We aimed to study the characteristics of wet work exposure in nursing. Method: Trained observers monitored the duration and frequency of

  10. Curvature controlled wetting in two dimensions

    DEFF Research Database (Denmark)

    Gil, Tamir; Mikheev, Lev V.

    1995-01-01

    . As the radius of the substrate r0→∞, the leading effect of the curvature is adding the Laplace pressure ΠL∝r0-1 to the pressure balance in the film. At temperatures and pressures under which the wetting is complete in planar geometry, Laplace pressure suppresses divergence of the mean thickness of the wetting...

  11. Cardiac dysfunction in HgCl2-induced nephrotic syndrome.

    Science.gov (United States)

    Moreira-Rodrigues, Mónica; Henriques-Coelho, Tiago; Moura, Cláudia; Vasques-Nóvoa, Francisco; Sampaio-Maia, Benedita; Pestana, Manuel; Leite-Moreira, Adelino F

    2010-03-01

    The experimental model of HgCl(2) injection is characterized by a systemic autoimmune disease which leads to the development of nephrotic syndrome (NS). NS seems to be accompanied by cardiovascular alterations, since patients with NS present an increased incidence in cardiac disease. The aim of our work was to study the effects of HgCl(2)-induced NS on myocardial function and morphometry. Normotensive Brown-Norway rats were injected with HgCl(2) (1 mg/kg, HgCl(2) group; n = 6, subcutaneous) or the vehicle (control group; n = 6, subcutaneous) on days 0, 2, 4, 7, 9 and 11. The animals were placed in metabolic cages for evaluation of urinary excretion of noradrenaline, sodium, total proteins, albumin and creatinine. Fourteen and 21 days after the first HgCl(2) injection, left ventricle (LV) hemodynamics was evaluated through pressure micromanometers in basal and isovolumetric heartbeats. The heart and gastrocnemius muscle weights and tibial length were also examined. In an additional group of animals cardiac dimensions and ejection fraction were assessed by echocardiography and LV apoptosis and fibrosis were studied. HgCl(2)-injected rats presented proteinuria, albuminuria, hyperlipidemia, anemia, sodium retention and ascites at day 14. These alterations were accompanied by LV hemodynamic changes only in isovolumetric heartbeats. Similarly, on day 21, HgCl(2)-injected rats presented proteinuria, albuminuria, hyperlipidemia, anemia, but no sodium retention or ascites. These animals presented LV systolic and diastolic dysfunction in both basal and isovolumetric heartbeats, as well as cardiac atrophy, LV fibrosis and an increase in myocyte apoptosis. In conclusion, HgCl(2)-induced NS is accompanied by LV dysfunction and can be a promising model for studying the link between NS and cardiac disease.

  12. Searching for Line Profile Variability in HgMn Stars

    CERN Document Server

    Turcotte, S; Knoglinger, P

    2002-01-01

    Spectra of four non-magnetic chemically peculiar late B type stars (HgMn) stars are analysed to detect periodic spectral line variations (LPVs). A procedure developed to study LPVs in Slowly Pulsating B stars has been adopted as pulsational properties of HgMn stars should be expected to be similar. In the preliminary results discussed here no conclusive evidence for periodic LPVs was uncovered. A more sensitive re-analysis of the data is under way.

  13. First observation of excited states in 173Hg93

    CERN Document Server

    O'Donnell, D; Scholey, C; Bianco, L; Capponi, L; Carroll, R J; Darby, I G; Donosa, L; Drummond, M; Ertugral, F; Greenlees, P T; Grahn, T; Hauschild, K; Herzan, A; Jakobsson, U; Jones, P; Joss, D T; Julin, R; Juutinen, S; Ketelhut, S; Labiche, M; Leino, M; Lopez-Martens, A; Mullholland, K; Nieminen, P; Peura, P; Rahkila, P; Rinta-Antila, S; Ruotsalainen, P; Sandzelius, M; Saren, J; Saygi, B; Simpson, J; Sorri, J; Thornthwaite, A; Uusitalo, J

    2012-01-01

    The neutron-deficient nucleus 173Hg has been studied following fusion-evaporation reactions. The observation of gamma rays decaying from excited states are reported for the first time and a tentative level scheme is proposed. The proposed level scheme is discussed within the context of the systematics of neighbouring neutron-deficient Hg nuclei. In addition to the gamma-ray spectroscopy, the alpha decay of this nucleus has been measured yielding superior precision to earlier measurements.

  14. Nitrogen Deposition in the Greater Tehran Metropolitan Area

    Directory of Open Access Journals (Sweden)

    Ali Salahi

    2001-01-01

    Full Text Available An investigation of air pollution in the Tehran metropolitan area between 1992–2000 indicated that there are significant amounts of nitrate ion (NO3–, over 30 kg/ha/year, deposited as wet deposition, compared to 13 kg/ha/year in the Chitgar Parkland near the Tehran metropolitan area. The amount of NO3– in warm seasons is twofold that of cold seasons (see Fig. 1, and there was a significant difference between cold and warm seasons (Table 1. Annual wet deposition of ammonia (NH3 was 10 kg/ha/year in the Chitgar Parkland[1].

  15. Porous Gold Films Fabricated by Wet-Chemistry Processes

    Directory of Open Access Journals (Sweden)

    Aymeric Pastre

    2016-01-01

    Full Text Available Porous gold films presented in this paper are formed by combining gold electroless deposition and polystyrene beads templating methods. This original approach allows the formation of conductive films (2 × 106 (Ω·cm−1 with tailored and interconnected porosity. The porous gold film was deposited up to 1.2 μm on the silicon substrate without delamination. An original zirconia gel matrix containing gold nanoparticles deposited on the substrate acts both as an adhesion layer through the creation of covalent bonds and as a seed layer for the metallic gold film growth. Dip-coating parameters and gold electroless deposition kinetics have been optimized in order to create a three-dimensional network of 20 nm wide pores separated by 20 nm thick continuous gold layers. The resulting porous gold films were characterized by GIXRD, SEM, krypton adsorption-desorption, and 4-point probes method. The process is adaptable to different pore sizes and based on wet-chemistry. Consequently, the porous gold films presented in this paper can be used in a wide range of applications such as sensing, catalysis, optics, or electronics.

  16. Crystal structure of K[Hg(SCN)3] - a redetermination.

    Science.gov (United States)

    Weil, Matthias; Häusler, Thomas

    2014-09-01

    The crystal structure of the room-temperature modification of K[Hg(SCN)3], potassium tri-thio-cyanato-mercurate(II), was redetermined based on modern CCD data. In comparison with the previous report [Zhdanov & Sanadze (1952 ▶). Zh. Fiz. Khim. 26, 469-478], reliability factors, standard deviations of lattice parameters and atomic coordinates, as well as anisotropic displacement parameters, were revealed for all atoms. The higher precision and accuracy of the model is, for example, reflected by the Hg-S bond lengths of 2.3954 (11), 2.4481 (8) and 2.7653 (6) Å in comparison with values of 2.24, 2.43 and 2.77 Å. All atoms in the crystal structure are located on mirror planes. The Hg(2+) cation is surrounded by four S atoms in a seesaw shape [S-Hg-S angles range from 94.65 (2) to 154.06 (3)°]. The HgS4 polyhedra share a common S atom, building up chains extending parallel to [010]. All S atoms of the resulting (1) ∞[HgS2/1S2/2] chains are also part of SCN(-) anions that link these chains with the K(+) cations into a three-dimensional network. The K-N bond lengths of the distorted KN7 polyhedra lie between 2.926 (2) and 3.051 (3) Å.

  17. Self-powered sensor for trace Hg2+ detection.

    Science.gov (United States)

    Wen, Dan; Deng, Liu; Guo, Shaojun; Dong, Shaojun

    2011-05-15

    A self-powered electrochemical sensor has been facilely designed for sensitive detection of Hg(2+) based on the inhibition of biocatalysis process of enzymatic biofuel cell (BFC) for the first time. The as-prepared one-compartment BFC, which was consisted of alcohol dehydrogenase supported on single-walled carbon nanohorns-based mediator system as the anode and bilirubin oxidase as the cathodic biocatalyst, generated an open circuit potential (V(oc)) of 636 mV and a maximum power density of 137 μW cm(-2). It was interestingly found that the presence of Hg(2+) would affect the performance of the constructed BFC (e.g., V(oc)). Taking advantage of the inhibitive effect of Hg(2+), a novel self-powered Hg(2+) sensor has been developed, which showed a linear range of 1-500 nM (R(2) = 0.999) with a detection limit of 1 nM at room temperature. In addition, this BFC-type sensor exhibited good selectivity for Hg(2+) against other common environmental metal ions, and the feasibility of the method for Hg(2+) detection in actual water samples (i.e., tap, ground, and lake water) was demonstrated with satisfactory results.

  18. NONMETALS DEPOSITS

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    <正>20102406 Chen Gang(China University of Geosciences,Beijing 100083,China);Li Fengming Discussion on Geological Characteristics and Genesis of Yuquanshan Graphite Deposit of Xinjiang(Xinjiang Geology,ISSN1000-8845,CN65-1092/P,27(4),2009,p.325-329,4 illus.,4 tables,5 refs.)Key words:graphite deposit,XinjiangYuquanshan graphite deposit of Xinjiang occurs in mica-quartz schist of Xingeer Information which belongs to Xinditate Group of Lower Pt in Kuluketage Block of Tarim paleo-continent,and experiences two mineralizing periods of

  19. Modeling early in situ wetting of a compacted bentonite buffer installed in low permeable crystalline bedrock

    Science.gov (United States)

    Dessirier, B.; Frampton, A.; Fransson, Å.; Jarsjö, J.

    2016-08-01

    The repository concept for geological disposal of spent nuclear fuel in Sweden and Finland is planned to be constructed in sparsely fractured crystalline bedrock and with an engineered bentonite buffer to embed the waste canisters. An important stage in such a deep repository is the postclosure phase following the deposition and the backfilling operations when the initially unsaturated buffer material gets hydrated by the groundwater delivered by the natural bedrock. We use numerical simulations to interpret observations on buffer wetting gathered during an in situ campaign, the Bentonite Rock Interaction Experiment, in which unsaturated bentonite columns were introduced into deposition holes in the floor of a 417 m deep tunnel at the Äspö Hard Rock Laboratory in Sweden. Our objectives are to assess the performance of state-of-the-art flow models in reproducing the buffer wetting process and to investigate to which extent dependable predictions of buffer wetting times and saturation patterns can be made based on information collected prior to buffer insertion. This would be important for preventing insertion into unsuitable bedrock environments. Field data and modeling results indicate the development of a de-saturated zone in the rock and show that in most cases, the presence or absence of fractures and flow heterogeneity are more important factors for correct wetting predictions than the total inflow. For instance, for an equal open-hole inflow value, homogeneous inflow yields much more rapid buffer wetting than cases where fractures are represented explicitly thus creating heterogeneous inflow distributions.

  20. Large-Scale Mercury Control Technology Testing for Lignite-Fired Utilities - Oxidation Systems for Wet FGD

    Energy Technology Data Exchange (ETDEWEB)

    Steven A. Benson; Michael J. Holmes; Donald P. McCollor; Jill M. Mackenzie; Charlene R. Crocker; Lingbu Kong; Kevin C. Galbreath

    2007-03-31

    Mercury (Hg) control technologies were evaluated at Minnkota Power Cooperative's Milton R. Young (MRY) Station Unit 2, a 450-MW lignite-fired cyclone unit near Center, North Dakota, and TXU Energy's Monticello Steam Electric Station (MoSES) Unit 3, a 793-MW lignite--Powder River Basin (PRB) subbituminous coal-fired unit near Mt. Pleasant, Texas. A cold-side electrostatic precipitator (ESP) and wet flue gas desulfurization (FGD) scrubber are used at MRY and MoSES for controlling particulate and sulfur dioxide (SO{sub 2}) emissions, respectively. Several approaches for significantly and cost-effectively oxidizing elemental mercury (Hg{sup 0}) in lignite combustion flue gases, followed by capture in an ESP and/or FGD scrubber were evaluated. The project team involved in performing the technical aspects of the project included Babcock & Wilcox, the Energy & Environmental Research Center (EERC), the Electric Power Research Institute, and URS Corporation. Calcium bromide (CaBr{sub 2}), calcium chloride (CaCl{sub 2}), magnesium chloride (MgCl{sub 2}), and a proprietary sorbent enhancement additive (SEA), hereafter referred to as SEA2, were added to the lignite feeds to enhance Hg capture in the ESP and/or wet FGD. In addition, powdered activated carbon (PAC) was injected upstream of the ESP at MRY Unit 2. The work involved establishing Hg concentrations and removal rates across existing ESP and FGD units, determining costs associated with a given Hg removal efficiency, quantifying the balance-of-plant impacts of the control technologies, and facilitating technology commercialization. The primary project goal was to achieve ESP-FGD Hg removal efficiencies of {ge}55% at MRY and MoSES for about a month.

  1. Assessment of Hg contamination and exposure to miners and schoolchildren at a small-scale gold mining and recovery operation in Thailand.

    Science.gov (United States)

    Umbangtalad, S; Parkpian, P; Visvanathan, C; Delaune, R D; Jugsujinda, A

    2007-12-01

    Gold extracted by Hg-amalgamation process, which can cause both health and environmental problems, is widespread in South East Asia including Myanmar, Laos, Cambodia, and Thailand. Small-scale gold mining operations have been carried out since the year 2000 in Phanom Pha District, Phichit Province, Thailand. Since no data is available for evaluating Hg exposure, an investigation of mercury (Hg) contamination and exposure assessment was carried out at this mine site. Environmental monitoring illustrated the total Hg in water was as high as 4 microg/l while Hg in sediment ranged between 102 to 325 microg/kg dry weight. Both Hg deposition from the air (1.28 microg/100 cm(2)/day) and concentration in surface soil (20,960 microg/kg dry weight) were elevated in the area of amalgamation. The potential of Hg exposure to miners as well as to schoolchildren was assessed. The concentrations of Hg in urine of 79 miners who were directly (group I) or indirectly (group II) involved in the gold recovery operation were 32.02 and 20.04 microg/g creatinine, respectively, which did not exceed regulatory limits (35 microg/g creatinine). Hair Hg levels in both groups (group I and group II) also were not significantly higher than the non-exposed group. In terms of risk factors, gender and nature of food preparation and consumption were the two significant variables influencing the concentration of Hg in urine of miners (P < 0.05). A hazard quotient (HQ) was estimated based on the inorganic Hg exposure of individual miners. The HQ values of group I were in a range 16 to 218 times higher than the safety level set as 1. By comparison the group II HQ index was very low (0.03-0.39). The miners in group I who worked and ate food from this area experienced potentially high exposure to Hg associated with the mining process. In a second Hg exposure assessment, a group of 59 schoolchildren who attended an elementary school near the gold mine site was evaluated for Hg exposure. A slightly higher

  2. Persistent Hg contamination and occurrence of Hg-methylating transcript (hgcA) downstream of a chlor-alkali plant in the Olt River (Romania).

    Science.gov (United States)

    Bravo, Andrea G; Loizeau, Jean-Luc; Dranguet, Perrine; Makri, Stamatina; Björn, Erik; Ungureanu, Viorel Gh; Slaveykova, Vera I; Cosio, Claudia

    2016-06-01

    Chlor-alkali plants using mercury (Hg) cell technology are acute point sources of Hg pollution in the aquatic environment. While there have been recent efforts to reduce the use of Hg cells, some of the emitted Hg can be transformed to neurotoxic methylmercury (MeHg). Here, we aimed (i) to study the dispersion of Hg in four reservoirs located downstream of a chlor-alkali plant along the Olt River (Romania) and (ii) to track the activity of bacterial functional genes involved in Hg methylation. Total Hg (THg) concentrations in water and sediments decreased successively from the initial reservoir to downstream reservoirs. Suspended fine size particles and seston appeared to be responsible for the transport of THg into downstream reservoirs, while macrophytes reflected the local bioavailability of Hg. The concentration and proportion of MeHg were correlated with THg, but were not correlated with bacterial activity in sediments, while the abundance of hgcA transcript correlated with organic matter and Cl(-) concentration, indicating the importance of Hg bioavailability in sediments for Hg methylation. Our data clearly highlights the importance of considering Hg contamination as a legacy pollutant since there is a high risk of continued Hg accumulation in food webs long after Hg-cell phase out.

  3. NONMETALS DEPOSITS

    Institute of Scientific and Technical Information of China (English)

    2014-01-01

    <正>20140876 Gao Junbo(College of Resources and Environmental Engineering,Guizhou University,Guiyang 550025,China);Yang Ruidong Study on the Strontium Isotopic Composition of Large Devonian Barite Deposits from Zhenning,Guizhou Province(Geochimica,

  4. Sputtered Ag thin films with modified morphologies: Influence on wetting property

    Energy Technology Data Exchange (ETDEWEB)

    Dutheil, P., E-mail: perrine.dutheil@univ-orleans.fr [GREMI, UMR 7344- Université D’Orléans, 14 rue d’Issoudun, BP 6744, Orléans 45067 (France); Thomann, A.L.; Lecas, T.; Brault, P. [GREMI, UMR 7344- Université D’Orléans, 14 rue d’Issoudun, BP 6744, Orléans 45067 (France); Vayer, M. [ICMN, UMR 7374- Université D’Orléans, 1b rue de la Férollerie, Orléans 45071 (France)

    2015-08-30

    Graphical abstract: - Highlights: • Ag thin films are deposited by DC magnetron sputtering on Si and W/Si layers. • The influence of the W underlayer morphology on Ag film growth is evidenced. • Variation of the Ag growth mode and roughness is investigated by SEM and AFM. • Wetting property is correlated to the roughness of Ag deposits on Si and W layers. - Abstract: Silver thin films with thickness ranging from 3 nm to 33 nm were sputter deposited onto silicon wafers and tungsten layers. Those W layers were previously synthesized in the same DC magnetron sputter deposition system with various experimental conditions (argon pressure, target to substrate distance) in order to stabilize different surface morphologies. SEM observations and AFM images showed that the growth mode of Ag films is similar on Si substrates and on the smoothest W layers, whereas it is modified for rough W layers made of sharp grains. The effect of the W layer morphology on Ag film growth was clearly evidenced when the deposition took place at high temperature. It is seen that performing the deposition onto substrates of various morphologies allows tailoring the wetting property of the Ag deposit.

  5. NONMETALS DEPOSITS

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    <正>20122457 Cai Jianshe ( Fujian Institute of Geological Survey and Drawing,Fuzhou 350011,China ) On the Geologic Characteristics and Genesis of the Longtangsi Fluorite Deposit in Pucheng County,Fujian Province ( Geology of Fujian,ISSN1001-3970,CN35-1080 / P,30 ( 4 ), 2011,p.301-306,3illus.,1table,6 refs.,with English abstract ) Key words:fluorspar deposit,Fujian Province

  6. Hg $L_{3}$ edge absorption study of the $HgBa_{2}CuO_{4}\\delta$ superconductor

    CERN Document Server

    Ziyu, Wu; Bianconi, A

    2001-01-01

    The HgBa/sub 2/CuO/sub 4+ delta / superconductor has been studied by high resolution Hg L/sub 3/ X-ray absorption near-edge structure (XANES) spectroscopy. The XANES spectrum has been simulated by full multiple-scattering calculations in order to explore the origin of different features in the experimental spectrum. The experimental Hg L/sub 3/-edge spectrum could be well reproduced by considering a cluster of 85 atoms, containing 10 shells, within a radius of about 7 AA from the central Hg atom. The low energy spectral feature in the XANES spectrum is found to be due to a transition from the Hg p states to the electronic states hybridized with higher shell Ba atoms. This implies that the transition features in the Hg L/sub 3/- edge XANES are strongly influenced by medium range order effects unlike the case of L/sub 3/ edge of 3d transition metals where short- range order is enough to describe the main transition features. (25 refs).

  7. Hg SOIL GAS AND Hg SOIL DISTRIBUTION AROUND FORMER „ZRINSKI“ MINE ON MT. MEDVEDNICA, CROATIA

    Directory of Open Access Journals (Sweden)

    Nataša Jug

    2008-12-01

    Full Text Available The purpose of this study is to present the field and laboratory researches, statistical analyses and graphical displays of the results of Hg soil gas and Hg soil distribution in the area around former mining site „Zrinski“ on Mt. Medvednica. The values of overall Hg concentrations in the soil gas show lognormal distribution, and their spatial distribution outlines the connection with the present Pb-Ag-Zn mineralization and confirms anthropogenic origin of uneven landscape relief (waste rock clusters. Regression analysis of the dependence between Hg contents in the soil gas and the distance from the mine entrance (correlation coefficient r also points to the considerable spatial dependence. Hg soil contents show as well distribution similar to lognormal, and there is a slight correlation when compared with Hg soil gas content. Concentrations are mostly within background values, except in the immediate vicinity of the mine entrance where the values are significantly higher due to the mineralization influence concentrated in the waste-rock clusters. Soil pollution caused by mercury is of local character with the spreading tendency to the south-west because of the dominant relief influence. Mercury found in the soil of the research location derives from the present mineral body and former mining activities, while possible anthropogenic atmospheric inputs from remote sources can not be proven on the basic of conducted research studies (the paper is published in Croatian.

  8. Deposition of HgTe by electrochemical atomic layer epitaxy (EC-ALE)

    CSIR Research Space (South Africa)

    Venkatasamy, V

    2006-04-01

    Full Text Available and Received 17 November 2005; received in revised 0022-0728/$ - see front matter � 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.jelechem.2006.02.006 l atomic layer epitaxy (EC-ALE) n Jayaraju a, Stephen M. Cox b, Mathe a, John L. Stickney a... (1983). [7] N.H. Karam, R.G. Wolfson, I.B. Bhat, H. Ehsani, S.K. Ghandhi, Thin Solid Films 225 (1993) 261. [8] M.A.M. Seyam, A. Elfalaky, Vacuum 57 (2000) 31–41. [9] C. Janowitz, N. Orlowski, R. Manzke, Z. Golacki, J. Alloy. Compd. 328 (2001) 84...

  9. Forced wetting of a reactive surface.

    Science.gov (United States)

    Blake, T D

    2012-11-01

    The dynamic wetting of water on gelatin-coated poly(ethylene terephthalate) (GC-PET) has been investigated by forced wetting over a wide speed range and compared with earlier data obtained with unmodified PET. The results were analysed according to the molecular-kinetic theory of dynamic wetting (MKT). Both substrates show complex behaviour, with separate low- and high-speed modes. For the GC-PET, this is attributed to a rapid change in the wettability of the substrate on contact with water, specifically a surface molecular transformation from hydrophobic to hydrophilic. This results in a smooth wetting transition from one mode to the other. For the PET, the bimodal behaviour is attributed to surface heterogeneity, with the low-speed dynamics dominated by interactions with polar sites on the substrate that become masked at higher speeds. In this case, the transition is discontinuous. The study has general ramifications for the investigation of any wetting processes in which a physicochemical transformation takes place at the solid surface on contact with the liquid. In particular, it shows how forced wetting, combined with the MKT, can reveal subtle details of the processes involved. It is unlikely that similar insight could be gained from spontaneous wetting studies, such as spreading drops.

  10. Historical atmospheric mercury emissions and depositions in North America compared to mercury accumulations in sedimentary records

    Science.gov (United States)

    Pirrone, Nicola; Allegrini, Ivo; Keeler, Gerald J.; Nriagu, Jerome O.; Rossmann, Ronald; Robbins, John A.

    Gold and silver production in North America (included United States, Canada and Mexico) released a large amount of mercury to the atmosphere until well into this century when mercury (Hg) amalgamation was replaced by cyanide concentration. Since then, emissions from industries have been the dominant anthropogenic sources of atmospheric Hg in North America as a whole. Past Hg emissions from gold and silver extractions in North America during the 1800s do not show a clear evidence of atmospheric deposition occurred at the coring sites considered in this study. Estimated atmospheric emissions of Hg in North America peaked in 1879 (at about 1708 t yr -1) and 1920 (at about 940 t yr -1), primarily due to Hg emissions from gold and silver mining. After the Great Economic Depression (1929) Hg emissions peaked again in the 1947 (274 t yr -1), in 1970 (325 t yr -1) and in 1989 (330 t yr -1) as result of increased Hg emissions from industrial sources, though improvements in the emissions control technology in United States and Canada have been substantial. Estimates of total atmospheric deposition fluxes of Hg to water and terrestrial receptors were in the range of 14.3-19.8 μg m -2 yr -1 in North America as a whole, and averaged 135 μg m -2 yr -1 (global background + local emissions) in the Great Lakes. These values were in good agreement with recent estimates reported in literature. The comparison of atmospheric Hg deposition fluxes with Hg accumulation rates in sediment cores suggests that atmospheric deposition was the major source of Hg entering the lakes system at coring sites, however, important contributions to Lake Ontario sediment cores sites from 1940 to 1970 were likely originated from local point sources (i.e. direct discharges).

  11. Superconducting Hg-Based Mixed Oxides and Oxyfluorides

    Science.gov (United States)

    Antipov, E. V.

    2000-09-01

    Syntheses under high pressure and under controlled mercury and oxygen partial pressures of different members of the HgBa2Can-1CunO2n+2+δ series have been developed. There are two main parameters influencing Tc in this family: width of a perovskite slab (n) and concentration (δ) of the extra oxygen located in the Hg layer. The increase of Tc with n occurs until the third member, while after that it decreases. All the members of the series exhibit similar cupola shaped dependencies of Tc vs. δ. Strongly overdoped high members of the series with n = 3-5 were prepared only using high pressure technique and BaO2 as an internal oxidizer. Neutron powder diffraction experiments were carried out for monophase oxygenated HgBa2CuO4F4+δ and fluorinated HgBa2CuO4Fδ samples with different extra oxygen or fluorine content and Tc values. Fluorinated series also exhibits the cupola -like behavior for the Tc vs. δ dependence. NPD showed twice the amount of extra fluorine in comparison with those for the oxygenated Hg-1201 phases with close Tc's. The exchange of the extra oxygen by double amount of fluorine causes shortening of the apical Cu-O distances, while the in-plane ones, as well as Tc, do not vary. The influence of the external pressure on the structure and Tc of Hg-1201 strongly depends on the doping level. The increase of the extra oxygen content on going from underdoped to overdoped state results in the larger compression of the apical Cu-O and Ba-OHg distances while the HgO2 dumbbell as well as the distance between Ba and O from the (CuO2) layers becomes practically pressure independent. These results together with the data for fluorinated materials allow to elucidate the crucial structural features responsible for the Tc variation under high pressure.

  12. Effects of different wetting layers on the growth of smooth ultra-thin silver thin films

    Science.gov (United States)

    Ni, Chuan; Shah, Piyush; Sarangan, Andrew M.

    2014-09-01

    Ultrathin silver films (thickness below 10 nm) are of great interest as optical coatings on windows and plasmonic devices. However, producing these films has been a continuing challenge because of their tendency to form clusters or islands rather than smooth contiguous thin films. In this work we have studied the effect of Cu, Ge and ZnS as wetting layers (1.0 nm) to achieve ultrasmooth thin silver films. The silver films (5 nm) were grown by RF sputter deposition on silicon and glass substrates using a few monolayers of the different wetting materials. SEM imaging was used to characterize the surface properties such as island formation and roughness. Also the optical properties were measured to identify the optical impact of the different wetting layers. Finally, a multi-layer silver based structure is designed and fabricated, and its performance is evaluated. The comparison between the samples with different wetting layers show that the designs with wetting layers which have similar optical properties to silver produce the best overall performance. In the absence of a wetting layer, the measured optical spectra show a significant departure from the model predictions, which we attribute primarily to the formation of clusters.

  13. Bioaerosol deposition on an air-conditioning cooling coil

    Science.gov (United States)

    Wu, Yan; Chen, Ailu; Luhung, Irvan; Gall, Elliott T.; Cao, Qingliang; Chang, Victor Wei-Chung; Nazaroff, William W.

    2016-11-01

    This study is concerned with the role of a fin-and-tube heat exchanger in modifying microbial indoor air quality. Specifically, depositional losses of ambient bioaerosols and particles onto dry (not cooled) and wet (cool) coil surfaces were measured for different airspeeds passing through the test coil. Total, bacterial and fungal DNA concentrations in condensate water produced by a wet coil were also quantified by means of fluorescent dsDNA-binding dye and qPCR assays. Results revealed that the deposition of bioaerosols and total particles is substantial on coil surfaces, especially when wet and cool. The average deposition fraction was 0.14 for total DNA, 0.18 for bacterial DNA and 0.22 for fungal DNA on the dry coil, increasing to 0.51 for total DNA, 0.50 for bacterial DNA and 0.68 for fungal DNA on the wet coil. Overall, as expected, deposition fractions increased with increasing particle size and increasing airspeed. Deposited DNA was removed from the cooling coil surfaces through the flow of condensing water at a rate comparable to the rate of direct deposition from air. A downward trend of bacterial and fungal DNA measured in condensate water over time provides suggestive evidence of biological growth on heat exchangers during nonoperational times of a ventilation system. This investigation provides new information about bioaerosol deposition onto a conventional fin-and-tube cooling coil, a potentially important factor influencing indoor exposure to microbial aerosols in air-conditioned buildings.

  14. Nitrogen deposition: the up and down side for production agriculture.

    Science.gov (United States)

    Pamela Padgett

    2009-01-01

    Deposition of nitrogen-containing air pollutants contributes as much as 80 kg-N yr-1 to rural lands in proximity to large urban centers. Even in areas distant from pollution sources atmospheric deposition in the US, and much of Europe, is 5 to 10 times higher than natural background levels. Wet deposition in rain, snow, and fog is relatively easy to measure and has...

  15. Natural and anthropogenic variations in atmospheric mercury deposition during the Holocene near Quelccaya Ice Cap, Peru

    Science.gov (United States)

    Beal, Samuel A.; Kelly, Meredith A.; Stroup, Justin S.; Jackson, Brian P.; Lowell, Thomas V.; Tapia, Pedro M.

    2014-04-01

    Mercury (Hg) is a toxic metal that is transported globally through the atmosphere. Emissions of Hg from mineral reservoirs and recycling between soil/biomass, oceans, and the atmosphere are fundamental to the global Hg cycle, yet past emissions from anthropogenic and natural sources are not fully constrained. We use a sediment core from Yanacocha, a headwater lake in southeastern Peru, to study the anthropogenic and natural controls on atmospheric Hg deposition during the Holocene. From 12.3 to 3.5 ka, Hg fluxes in the record are relatively constant (mean ± 1σ: 1.4 ± 0.6 µg m-2 a-1). Past Hg deposition does not correlate with changes in regional temperature and precipitation or with most large volcanic events that occurred regionally (~300-400 km from Yanacocha) and globally. In 1450 B.C. (3.4 ka), Hg fluxes abruptly increased and reached the Holocene-maximum flux (6.7 µg m-2 a-1) in 1200 B.C., concurrent with a ~100 year peak in Fe and chalcophile metals (As, Ag, Tl) and the presence of framboidal pyrite. Continuously elevated Hg fluxes from 1200 to 500 B.C. suggest a protracted mining-dust source near Yanacocha that is identical in timing to documented pre-Incan cinnabar mining in central Peru. During Incan and Colonial time (A.D. 1450-1650), Hg deposition remains elevated relative to background levels but lower relative to other Hg records from sediment cores in central Peru, indicating a limited spatial extent of preindustrial Hg emissions. Hg fluxes from A.D. 1980 to 2011 (4.0 ± 1.0 µg m-2 a-1) are 3.0 ± 1.5 times greater than preanthropogenic fluxes.

  16. Wetting transitions at soft, sliding interfaces

    Science.gov (United States)

    Martin, A.; Clain, J.; Buguin, A.; Brochard-Wyart, F.

    2002-03-01

    We observe (by optical interferometry) the contact of a rubber cap squeezing a nonwetting liquid against a plate moving at velocity U. At low velocities, the contact is dry. It becomes partially wet above a threshold velocity Vc1, with two symmetrical dry patches on the rear part. Above a second velocity Vc2, the contact is totally wet. This regime U>Vc2 corresponds to the hydroplaning of a car (decelerating on a wet road). We interpret the transitions at Vc1, Vc2 in terms of a competition between (a) liquid invasion induced by shear (b) spontaneous dewetting of the liquid (between nonwettable surfaces).

  17. Catalytic wet oxidation of black liquor

    OpenAIRE

    Viader Riera, Gerard

    2012-01-01

    The major aspects of wet air oxidation and catalytic wet air oxidation have been reviewed in this work paying special attention to the reaction mechanisms, kinetics and the industrial process. In the experimental section a set of heterogeneous catalysts have been tested in the wet oxidation of non-wood black liquor. The oxidation runs were performed batchwise in a laboratory-scale mechanically stirred slurry reactor for 1 h at a temperature of 170°C and total pressure of 12 bar. Pure oxygen w...

  18. Our experience with wet-wrap treatment.

    Science.gov (United States)

    Albarrán-Planelles, C; Jiménez-Gallo, D; Linares-Barrios, M; Martínez-Rodríguez, A

    2014-04-01

    A wide range of treatments are currently available for severe atopic dermatitis, including systemic therapies such as ciclosporin, corticosteroids, azathioprine, methotrexate, mofetil mycophenolate, and omalizumab. In patients who can no longer take systemic drugs or who need a dose reduction, wet-wrap treatment can be an excellent option. To date, wet wraps have mostly been used in severe cases of childhood atopic dermatitis. We report our experience with wet-wrap treatment in 5 adults with atopic dermatitis and 2 with nodular prurigo. The results were satisfactory and there were few adverse effects. Copyright © 2013 Elsevier España, S.L. and AEDV. All rights reserved.

  19. Atmospheric deposition 2000. NOVA 2003; Atmosfaerisk deposition 2000. NOVA 2003

    Energy Technology Data Exchange (ETDEWEB)

    Ellermann, T.; Hertel, O.; Hovmand, M.F.; Kemp, K.; Skjoeth, C.A.

    2001-11-01

    This report presents measurements and calculations from the atmospheric part of NOVA 2003 and covers results for 2000. It summarises the main results concerning concentrations and depositions of nitrogen, phosphorus and sulphur compounds related to eutrophication and acidification. Depositions of atmospheric compounds to Danish marine waters as well as land surface are presented. Measurements: In 2000 the monitoring program consisted of eight stations where wet deposition of ammonium, nitrate, phosphate (semi quantitatively) and sulphate were measured using bulk precipitation samplers. Six of the stations had in addition measurements of atmospheric content of A, nitrogen, phosphorus, and sulphur compounds in gas and particulate phase carried out by use of filter pack samplers. Filters were analysed at the National Environmental Research Institute. Furthermore nitrogen dioxide were measured using nitrogen dioxide filter samplers and monitors. Model calculations: The measurements in the monitoring program were supplemented with model calculations of concentrations and depositions of nitrogen and sulphur compounds to Danish land surface, marine waters, fjords and bays using the ACDEP model (Atmospheric Chemistry and Deposition). The model is a so-called trajectory model and simulates the physical and chemical processes in the atmosphere using meteorological and emission data as input. The advantage of combining measurements with model calculations is that the strengths of both methods is obtained. Conclusions concerning: 1) actual concentration levels at the monitoring stations, 2) deposition at the monitoring stations, 3) seasonal variations and 4) long term trends in concentrations and depositions are mainly based on the direct measurements. These are furthermore used to validate the results of the model calculations. Calculations and conclusions concerning: 1) depositions to land surface and to the individual marine water, 2) contributions from different emission

  20. National implementation of the UNECE convention on long-range transboundary air pollution (effects). Pt. 1. Deposition loads: methods, modelling and mapping results, trends

    Energy Technology Data Exchange (ETDEWEB)

    Gauger, Thomas [Federal Agricultural Research Centre, Braunschweig (DE). Inst. of Agroecology (FAL-AOE); Stuttgart Univ. (Germany). Inst. of Navigation; Haenel, Hans-Dieter; Roesemann, Claus [Federal Agricultural Research Centre, Braunschweig (DE). Inst. of Agroecology (FAL-AOE)] (and others)

    2008-09-15

    The report on the implementation of the UNECE convention on long-range transboundary air pollution Pt.1, deposition loads (methods, modeling and mapping results, trends) includes the following chapters: Introduction, deposition on air pollutants used for the input for critical loads in exceeding calculations, methods applied for mapping total deposition loads, mapping wet deposition, wet deposition mapping results, mapping dry deposition, dry deposition mapping results, cloud and fog mapping results, total deposition mapping results, modeling the air concentration of acidifying components and heavy metals, agricultural emissions of acidifying and eutrophying species.

  1. Mercury (Hg) burden in children: The impact of dental amalgam

    Energy Technology Data Exchange (ETDEWEB)

    Al-Saleh, Iman, E-mail: iman@kfshrc.edu.sa [Biological and Medical Research Department, King Faisal Specialist Hospital and Research Centre, PO Box: 3354, Riyadh 11211 (Saudi Arabia); Al-Sedairi, Al anoud [Department of Zoology, College of Science, King Saud University, PO Box: 24452, Riyadh 11495 (Saudi Arabia)

    2011-07-15

    The risks and benefits of using mercury (Hg) in dental amalgam have long been debated. This study was designed to estimate Hg body burden and its association with dental amalgam fillings in 182 children (ages: 5-15 years) living in Taif City. Hg was measured in urine (UHg), hair (HHg) and toenails (NHg) by the Atomic Absorption Spectrophotometer with Vapor Generator Accessory system. Urinary Hg levels were calculated as both micrograms per gram creatinine ({mu}g/g creatinine) and micrograms per liter ({mu}g/L). We found that children with amalgam fillings (N = 106) had significantly higher UHg-C levels than children without (N = 76), with means of 3.763 {mu}g/g creatinine versus 3.457 {mu}g/g creatinine, respectively (P = 0.019). The results were similar for UHg (P = 0.01). A similar pattern was also seen for HHg, with means of 0.614 {mu}g/g (N = 97) for children with amalgam versus 0.242 {mu}g/g (N = 74) for those without amalgam fillings (P = 0). Although the mean NHg was higher in children without amalgam (0.222 {mu}g/g, N = 61) versus those with (0.163 {mu}g/g, N = 101), the relationship was not significant (P = 0.069). After adjusting for many confounders, the multiple logistic regression model revealed that the levels of UHg-C and HHg were 2.047 and 5.396 times higher, respectively, in children with dental amalgam compared to those without (P < 0.01). In contrast, a significant inverse relationship was seen between NHg levels and dental amalgam fillings (P = 0.003). Despite the controversy surrounding the health impact of dental amalgam, this study showed some evidence that amalgam-associated Hg exposure might be related with symptoms of oral health, such as aphthous ulcer, white patches, and a burning-mouth sensation. Further studies are needed to reproduce these findings. The present study showed that significant numbers of children with or without amalgam had Hg levels exceeding the acceptable reference limits. The detrimental neurobehavioral and

  2. Overcoming phytoremediation limitations. A case study of Hg contaminated soil

    Science.gov (United States)

    Barbafieri, Meri

    2013-04-01

    Phytoremediation is a broad term that comprises several technologies to clean up water and soil. Despite the numerous articles appearing in scientific journals, very few field applications of phytoextraction have been successfully realized. The research here reported on Phytoextraction, the use the plant to "extract" metals from contaminated soil, is focused on implementations to overcome two main drawbacks: the survival of plants in unfavorable environmental conditions (contaminant toxicity, low fertility, etc.) and the often lengthy time it takes to reduce contaminants to the requested level. Moreover, to overcome the imbalance between the technology's potential and its drawbacks, there is growing interest in the use of plants to reduce only the fraction that is the most hazardous to the environment and human health, that is to target the bioavailable fractions of metals in soil. Bioavailable Contaminant Stripping (BCS) would be a remediation approach focused to remove the bioavailable metal fractions. BCS have been used in a mercury contaminated soil from Italian industrial site. Bioavailable fractions were determined by sequential extraction with H2O and NH4Cl.Combined treatments of plant hormone and thioligand to strength Hg uptake by crop plants (Brassica juncea and Helianthus annuus) were tested. Plant biomass, evapotranspiration, Hg uptake and distribution following treatments were compared. Results indicate the plant hormone, cytokinine (CK) foliar treatment, increased evapotranspiration rate in both tested plants. The Hg uptake and translocation in both tested plants increased with simultaneous addition of CK and TS treatments. B. juncea was the most effective in Hg uptake. Application of CK to plants grown in TS-treated soil lead to an increase in Hg concentration of 232% in shoots and 39% in roots with respect to control. While H. annuus gave a better response in plant biomass production, the application of CK to plants grown in TS-treated soil lead to

  3. Methionine stimulates motor impairment and cerebellar mercury deposition in methylmercury-exposed mice.

    Science.gov (United States)

    Zimmermann, Luciana T; dos Santos, Danúbia B; Colle, Dirleise; dos Santos, Alessandra A; Hort, Mariana A; Garcia, Solange C; Bressan, Lucas Paines; Bohrer, Denise; Farina, Marcelo

    2014-01-01

    Methylmercury (MeHg) is a highly toxic environmental contaminant that produces neurological and developmental impairments in animals and humans. Although its neurotoxic properties have been widely reported, the molecular mechanisms by which MeHg enters the cells and exerts toxicity are not yet completely understood. Taking into account that MeHg is found mostly bound to sulfhydryl-containing molecules such as cysteine in the environment and based on the fact that the MeHg-cysteine complex (MeHg-S-Cys) can be transported via the L-type neutral amino acid carrier transport (LAT) system, the potential beneficial effects of L-methionine (L-Met, a well known LAT substrate) against MeHg (administrated as MeHg-S-Cys)-induced neurotoxicity in mice were investigated. Mice were exposed to MeHg (daily subcutaneous injections of MeHg-S-Cys, 10 mg Hg/kg) and/or L-Met (daily intraperitoneal injections, 250 mg/kg) for 10 consecutive days. After treatments, the measured hallmarks of toxicity were mostly based on behavioral parameters related to motor performance, as well as biochemical parameters related to the cerebellar antioxidant glutathione (GSH) system. MeHg significantly decreased motor activity (open-field test) and impaired motor performance (rota-rod task) compared with controls, as well as producing disturbances in the cerebellar antioxidant GSH system. Interestingly, L-Met administration did not protect against MeHg-induced behavioral and cerebellar changes, but rather increased motor impairments in animals exposed to MeHg. In agreement with this observation, cerebellar levels of mercury (Hg) were higher in animals exposed to MeHg plus L-Met compared to those only exposed to MeHg. However, this event was not observed in kidney and liver. These results are the first to demonstrate that L-Met enhances cerebellar deposition of Hg in mice exposed to MeHg and that this higher deposition may be responsible for the greater motor impairment observed in mice simultaneously

  4. Spectroscopic variability and magnetic fields of HgMn stars

    CERN Document Server

    Hubrig, S; Ilyin, I; Korhonen, H; Savanov, I S; Dall, T; Schoeller, M; Cowley, C R; Briquet, M; Arlt, R

    2011-01-01

    The discovery of exotic abundances, chemical inhomogeneities, and weak magnetic fields on the surface of late B-type primaries in spectroscopic binaries has important implications not only for our understanding of the formation mechanisms of stars with Hg and Mn peculiarities themselves, but also for the general understanding of B-type star formation in binary systems. The origin of the abundance anomalies observed in late B-type stars with HgMn peculiarity is still poorly understood. The connection between HgMn peculiarity and membership in binary and multiple systems is supported by our observations during the last decade. The important result achieved in our studies of a large sample of HgMn stars is the finding that most HgMn stars exhibit spectral variability of various chemical elements, proving that the presence of an inhomogeneous distribution on the surface of these stars is a rather common characteristic and not a rare phenomenon. Further, in the studied systems, we found that all components are che...

  5. Bioaccumulation of Hg in the mushroom Pleurotus ostreatus

    Energy Technology Data Exchange (ETDEWEB)

    Bressa, G.; Cima, L.; Costa, P.

    1988-10-01

    The possibility of utilizing industrial, urban, and other wastes for the growth of a product which is directly edible by humans is fascinating. However, it is possible that many wastes containing toxic substances, for example, heavy metals, could reach the food chain and produce adverse effects on human health. To this end, we studied the possibility of bioaccumulation of Hg by a mushroom, Pleurotus ostreatus, grown on an artificial compost containing this element. Concentrations of 0.05, 0.1, and 0.2 mg/kg of Hg as Hg(NO/sub 3/)/sub 2/.H/sub 2/O were added to three groups of the same compost, successively inoculated with the mycelia of the mushroom. Higher concentrations strongly reduced the growth of the mycelia and therefore were not utilized. The concentrations of Hg in the substrate and in the mushroom were evaluated by AAS. The range of the accumulation factor was found to be 65-140, i.e., very marked. This finding suggests that the cultivation of P. ostreatus on substrates containing Hg from industrial and urban wastes could involve possible risks to human health.

  6. Are there tangled magnetic fields on HgMn stars?

    CERN Document Server

    Kochukhov, O; Piskunov, N; Jeffers, S V; Johns-Krull, C M; Keller, C U; Rodenhuis, M; Snik, F; Stempels, H C; Valenti, J A

    2013-01-01

    Several recent spectrophotometric studies failed to detect significant global magnetic fields in late-B HgMn chemically peculiar stars, but some investigations have suggested the presence of strong unstructured or tangled fields in these objects. We used detailed spectrum synthesis analysis to search for evidence of tangled magnetic fields in high-quality observed spectra of 8 slowly rotating HgMn stars and one normal late-B star. We also evaluated recent sporadic detections of weak longitudinal magnetic fields in HgMn stars based on the moment technique. Our analysis of the Zeeman broadening of magnetically sensitive spectral lines reveals no evidence of tangled magnetic fields in any of the studied HgMn or normal stars. We infer upper limits of 200-700 G for the mean magnetic field modulus -- much smaller than the field strengths implied by studies based on differential magnetic line intensification and quadratic field diagnostics. The new HARPSpol longitudinal field measurements for the extreme HgMn star H...

  7. Overcoming Etch Challenges on a 6″ Hg1- x Cd x Te MBE on Si Wafer

    Science.gov (United States)

    Apte, Palash; Norton, Elyse; Robinson, Solomon

    2017-10-01

    The effect of increasing photoresist (PR) thickness on the inductively coupled plasma (ICP) dry etched characteristics of a 6″ (c.15 cm) molecular beam epitaxy Hg1- x Cd x Te/Si wafer is investigated. It is determined that the Hg1- x Cd x Te etch rate (ER) does not vary significantly with a change in the PR thickness. Also, the vertical ER of the PR is seen to be independent of the PR thickness, but the lateral ER is seen to reduce significantly with increased PR thickness. Indeed, very little reduction in the pixel mesa area post-dry etch is seen for the thicker PR. Consequently, the trench sidewall angle is also seen to vary as a function of the PR thickness. Since ICP is the more attractive choice for dry etching Hg1- x Cd x Te, this simple, cost-effective way to extend the capabilities of dry etching (larger mesa top area post-dry etch, ability to create tailor-made trench sidewall angles for optimal conformal passivation deposition, and potential for reduced dry etch damage) described here would allow for the fabrication of next generation infrared detectors with increased yield and reduced cost. Although similar results have been presented using the electron cyclotron resonance system to dry etch Hg1- x Cd x Te, to the best of our knowledge, this is the first time that such results have been presented using an ICP system.

  8. Status of HgCdTe Barrier Infrared Detectors Grown by MOCVD in Military University of Technology

    Science.gov (United States)

    Kopytko, M.; Jóźwikowski, K.; Martyniuk, P.; Gawron, W.; Madejczyk, P.; Kowalewski, A.; Markowska, O.; Rogalski, A.; Rutkowski, J.

    2016-09-01

    In this paper we present the status of HgCdTe barrier detectors with an emphasis on technological progress in metalorganic chemical vapor deposition (MOCVD) growth achieved recently at the Institute of Applied Physics, Military University of Technology. It is shown that MOCVD technology is an excellent tool for HgCdTe barrier architecture growth with a wide range of composition, donor /acceptor doping, and without post-grown annealing. The device concept of a specific barrier bandgap architecture integrated with Auger-suppression is as a good solution for high-operating temperature infrared detectors. Analyzed devices show a high performance comparable with the state-of-the-art of HgCdTe photodiodes. Dark current densities are close to the values given by "Rule 07" and detectivities of non-immersed detectors are close to the value marked for HgCdTe photodiodes. Experimental data of long-wavelength infrared detector structures were confirmed by numerical simulations obtained by a commercially available software APSYS platform. A detailed analysis applied to explain dark current plots was made, taking into account Shockley-Read-Hall, Auger, and tunneling currents.

  9. Chemical cycling and deposition of atmospheric mercury in polar regions: review of recent measurements and comparison with models

    Science.gov (United States)

    Angot, Hélène; Dastoor, Ashu; De Simone, Francesco; Gårdfeldt, Katarina; Gencarelli, Christian N.; Hedgecock, Ian M.; Langer, Sarka; Magand, Olivier; Mastromonaco, Michelle N.; Nordstrøm, Claus; Pfaffhuber, Katrine A.; Pirrone, Nicola; Ryjkov, Andrei; Selin, Noelle E.; Skov, Henrik; Song, Shaojie; Sprovieri, Francesca; Steffen, Alexandra; Toyota, Kenjiro; Travnikov, Oleg; Yang, Xin; Dommergue, Aurélien

    2016-08-01

    Mercury (Hg) is a worldwide contaminant that can cause adverse health effects to wildlife and humans. While atmospheric modeling traces the link from emissions to deposition of Hg onto environmental surfaces, large uncertainties arise from our incomplete understanding of atmospheric processes (oxidation pathways, deposition, and re-emission). Atmospheric Hg reactivity is exacerbated in high latitudes and there is still much to be learned from polar regions in terms of atmospheric processes. This paper provides a synthesis of the atmospheric Hg monitoring data available in recent years (2011-2015) in the Arctic and in Antarctica along with a comparison of these observations with numerical simulations using four cutting-edge global models. The cycle of atmospheric Hg in the Arctic and in Antarctica presents both similarities and differences. Coastal sites in the two regions are both influenced by springtime atmospheric Hg depletion events and by summertime snowpack re-emission and oceanic evasion of Hg. The cycle of atmospheric Hg differs between the two regions primarily because of their different geography. While Arctic sites are significantly influenced by northern hemispheric Hg emissions especially in winter, coastal Antarctic sites are significantly influenced by the reactivity observed on the East Antarctic ice sheet due to katabatic winds. Based on the comparison of multi-model simulations with observations, this paper discusses whether the processes that affect atmospheric Hg seasonality and interannual variability are appropriately represented in the models and identifies research gaps in our understanding of the atmospheric Hg cycling in high latitudes.

  10. NONMETALS DEPOSITS

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    <正>20110947 Chen Xinglong(Guizhou Bureau of Nonferrous Metal and Nuclear Geology,Guiyang 550005,China);Gong Heqiang Endowment Factors and Development & Utilization Strategy of Bauxite Resource in North Guizhou Province(Guizhou Geology,ISSN1000-5943,CN52-1059/P,27(2),2010,p.106-110,6 refs.,with English abstract)Key words:bauxite deposit,Guizhou Province20110948 Dang Yanxia(Mineral Resource & Reservoir Evaluation Center,Urumiq 830000,China);Fan Wenjun Geological Features and a Primary Study of Metallogenesis of the Wucaiwang Zeolite Deposit,Fuyun County(Xinjiang Geology,ISSN1000-8845,CN65-1092/P,28(2),2010,p.167-170,2 illus.,1 table,5 refs.)Key words:zeolite deposit,Xinjiang Nearly all zeolite deposits in the world result from low-temperature-alteration of glass-bearing volcanic rocks.The southern slope of the Kalamali Mountain is one of the regions where medium to acid volcanics are major lithological type,thus it is a preferred area to look for zeolite deposit.The Wucaiwang zeolite ore district consists of mainly acid volcanic-clastic rocks.

  11. Developing Depositional Models for Mercury Contaminated Floodplain Deposits Using Geomorphic Mapping and GIS in South River, Virginia

    Science.gov (United States)

    Barbieri, A.; Pizzuto, J.; O'Neal, M. A.; Rhoades, E.

    2007-12-01

    Mercury was introduced into the South River from the 1930s to the 1950s from an industrial plant in Waynesboro, Virginia. Mercury contamination in fish tissue continues to exceed acceptable levels. The contaminated sediments in the river's floodplains are probably the present source of mercury to the South River ecosystem. Locating and determining the extent and depositional history of these deposits are important for understanding the mercury cycle in the river as well as for remediation plans. The South River is a sinuous, single thread alluvial river with frequent bedrock exposures along its bed and banks. Overbank deposits are discontinuous and thin. Rates of lateral migration by the South River are extremely low, averaging 0.02 m/yr, and the river has been influenced by mill dams along a 19 km study reach. This 19 km section of the 37 km river reach was selected for the study because of its high concentration of Hg. Six different categories of floodplain deposits dating from 1937-2005 have been identified throughout the river using studies of historical aerial photographs in a GIS framework, field mapping, dendro- and radionuclide dating, grain size and Hg analysis. Not surprisingly, traditional depositional models of meandering rivers do not apply. Floodplain depositional units include mill dam deposits, point bar/bench deposits, concave bank bench deposits, islands, cattle deposits, and tributary confluences deposits. The most important deposits for sequestering historic mercury are those that also store the most silt and clay. These include mill dam deposits, point bar/bench deposits, concave bank deposits, and tributary confluence deposits. Many of these deposits represent reservoirs of mercury-contaminated sediments that could supply significant amounts of mercury into the river presently and in the future.

  12. Hg soil pollution around the Flix chlor-alkali plant

    Science.gov (United States)

    Esbrí, José Maria; López-Berdoces, Miguel Angel; Martínez-Coronado, Alba; Fernández-Calderon, Sergio; Díez, Sergi; León Higueras, Pablo

    2014-05-01

    meander, downstream the town area. Mercury seems to be partially available to plants, especially in the CAP surrounding area, where total mercury levels in olive leaves reach maximum values of 1.27 mg kg-1, and average concentration is 0.48 mg kg-1, higher than tolerable level for agronomic crops establish by Kabata-Pendias (2010) in 0.2 mg kg-1. Although correlation coefficients between Hgsoil-Hgplants are low, is possible to characterize plant absorption by logistic curves. Main conclusions of this work are: i) A fraction of mercury vapor emitted by CAP has been deposited on local soils by wet and dry deposition; ii) Mercury in local soils seems to be bioavailable for plants as highlights mercury levels in olive trees; iii) In this work we have identified risks areas with polluted soils.

  13. Structure of Wet Specimens in Electron Microscopy

    Science.gov (United States)

    Parsons, D. F.

    1974-01-01

    Discussed are past work and recent advances in the use of electron microscopes for viewing structures immersed in gas and liquid. Improved environmental chambers make it possible to examine wet specimens easily. (Author/RH)

  14. National Ignition Facility wet weather construction plan

    Energy Technology Data Exchange (ETDEWEB)

    Kugler, A N

    1998-01-01

    This report presents a wet weather construction plan for the National Ignition Facility (NIF) construction project. Construction of the NIF commenced in mid- 1997, and excavation of the site was completed in the fall. Preparations for placing concrete foundations began in the fall, and above normal rainfall is expected over the tinter. Heavy rainfall in late November impacted foundation construction, and a wet weather construction plan was determined to be needed. This wet weather constiction plan recommends a strategy, techniques and management practices to prepare and protect the site corn wet weather effects and allow construction work to proceed. It is intended that information in this plan be incorporated in the Stormwater Pollution Prevention Plan (SWPPP) as warranted.

  15. Wet granular matter a truly complex fluid

    CERN Document Server

    Herminghaus, Stephan

    2013-01-01

    This is a monograph written for the young and advanced researcher who is entering the field of wet granular matter and keen to understand the basic physical principles governing this state of soft matter. It treats wet granulates as an instance of a ternary system, consisting of the grains, a primary, and a secondary fluid. After addressing wetting phenomena in general and outlining the basic facts on dry granular systems, a chapter on basic mechanisms and their effects is dedicated to every region of the ternary phase diagram. Effects of grain shape and roughness are considered as well. Rather than addressing engineering aspects such as existing books on this topic do, the book aims to provide a generalized framework suitable for those who want to understand these systems on a more fundamental basis. Readership: For the young and advanced researcher entering the field of wet granular matter.

  16. Tualatin River - Wet Prairie Restoration Phase III

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Forty five acres of wet prairie and 11 acres of adjacent lands were treated for reed canarygrass in this ongoing project. Federally threatened Nelson’s...

  17. Structure of Wet Specimens in Electron Microscopy

    Science.gov (United States)

    Parsons, D. F.

    1974-01-01

    Discussed are past work and recent advances in the use of electron microscopes for viewing structures immersed in gas and liquid. Improved environmental chambers make it possible to examine wet specimens easily. (Author/RH)

  18. Critical point wetting drop tower experiment

    Science.gov (United States)

    Kaukler, W. F.; Tcherneshoff, L. M.; Straits, S. R.

    1984-01-01

    Preliminary results for the Critical Point Wetting CPW Drop Tower Experiment are produced with immiscible systems. Much of the observed phenomena conformed to the anticipated behavior. More drops will be needed to test the CPW theory with these immiscible systems.

  19. Wetting behavior of alternative solder alloys

    Energy Technology Data Exchange (ETDEWEB)

    Hosking, F.M.; Vianco, P.T.; Hernandez, C.L.; Rejent, J.A.

    1993-07-01

    Recent economic and environmental issues have stimulated interest in solder alloys other than the traditional Sn-Pb eutectic or near eutectic composition. Preliminary evaluations suggest that several of these alloys approach the baseline properties (wetting, mechanical, thermal, and electrical) of the Sn-Pb solders. Final alloy acceptance will require major revisions to existing industrial and military soldering specifications. Bulk alloy and solder joint properties are consequently being investigated to validate their producibility and reliability. The work reported in this paper examines the wetting behavior of several of the more promising commercial alloys on copper substrates. Solder wettability was determined by the meniscometer and wetting balance techniques. The wetting results suggest that several of the alternative solders would satisfy pretinning and surface mount soldering applications. Their use on plated through hole technology might be more difficult since the alloys generally did not spread or flow as well as the 60Sn-40Pb solder.

  20. Adult Bed-Wetting: A Concern?

    Science.gov (United States)

    ... D. Bed-wetting that starts in adulthood (secondary enuresis) is uncommon and requires medical evaluation. Causes of ... Erik P. Castle, M.D. References Adult nocturnal enuresis. National Association for Continence. http://www.nafc.org/ ...

  1. A WET TALE: TOXICITY OF COMPLEX EFFLUENTS

    Science.gov (United States)

    This course covers standards, regulations, policy, guidance and technical aspects of implementing the whole effluent toxicity program. The curriculum incorporates rationale and information on WET test requirements from USEPA documents, such as the Technical Support Document for W...

  2. METALS DEPOSITS

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    <正>20091594 Bao Yafan(The Third Geologic Survey of Jilin Province,Siping 136000,China);Liu Yanjun Relations between Bashenerxi Granite,West Dongkunlun and Baiganhu Tungsten-Tin Deposit(Jilin Geology,ISSN1001-2427,CN22-1099/P,27(3),2008,p.56-59,67,5 illus.,2 tables,7 refs.,with English abstract)Key words:tungsten ores,tin ores,monzogranite,Kunlun Mountains20091595 Chen Fuwen(Yichang Institute of Geology and Mineral Resources,China Geological Survey,Yichang 443003,China);Dai Pingyun Metallogenetic and Isotopic Chronological Study on the Shenjiaya Gold Deposit in Xuefeng Mountains,Hunan Province(Acta Geologica Sinica,ISSN0001-5717,CN11-1951/P,82(7),2008,p.906-911,3 illus.,2 tables,30 refs.)Key words:gold ores,HunanThe Shenjiaya gold deposit is a representative one

  3. Crystal structure of Hg2SO4 – a redetermination

    Directory of Open Access Journals (Sweden)

    Matthias Weil

    2014-09-01

    Full Text Available The crystal structure of mercury(I sulfate (or mercurous sulfate, Hg2SO4, was re-determined based on modern CCD data. In comparison with the previous determination from Weissenberg film data [Dorm (1969. Acta Chem. Scand. 23, 1607–1615], all atoms were refined with anisotropic displacement parameters, leading to higher precision in terms of bond lengths and angles [e.g. Hg—Hg = 2.5031 (7 compared to 2.500 (3Å]. The structure consists of alternating rows along [001] of Hg22+ dumbbells (generated by inversion symmetry and SO42− tetrahedra (symmetry 2. The dumbbells are linked via short O—Hg—Hg—O bonds to the sulfate tetrahedra into chains extending parallel to [20-1]. More remote O—Hg—Hg—O bonds connect these chains into a three-dimensional framework.

  4. Characterization studies of purified HgI{sub 2} precursors

    Energy Technology Data Exchange (ETDEWEB)

    Schieber, M. E-mail: Schieber@vms.huji.ac.il; Zuck, A.; Sanguinetti, S.; Montalti, M.; Braiman, M.; Melekhov, L.; Nissenbaum, J.; Grilli, E.; Guzzi, M.; Turchetta, R.; Dulinski, W.; Husson, D.; Riester, J.L

    1999-06-01

    The ability of HgI{sub 2} powders, used as precursors in mercuric iodide crystal growth, to produce high-quality detectors may be predicted by non-destructive methods like photoluminescence. In fact, it is possible to correlate the presence and the intensity ratio of specific bands in the photoluminescence spectrum of a HgI{sub 2} crystal to its impurity content and stoichiometry. These quantities determine the detector grade that may be achieved using that starting material. Nine different HgI{sub 2} precursors, obtained by different purification methods, have been characterized. The lowest impurity content is achieved via poly-ethylene treatment, which gives also a powder of relatively good stoichiometric quality.

  5. Wetting and phase separation at surfaces

    Indian Academy of Sciences (India)

    Sanjay Puri; Kurt Binder

    2005-06-01

    We study the problem of surface-directed spinodal decomposition, viz., the dynamical interplay of wetting and phase separation at surfaces. In particular, we focus on the kinetics of wetting-layer growth in a semi-infinite geometry for arbitrary surface potentials and mixture compositions. We also present representative results for phase separation in confined geometries, e.g., cylindrical pores, thin films, etc.

  6. Biodegradation of wet-white leather

    OpenAIRE

    Ollé Otero, Lluís; Jorba Rafart, Montse; Font Vallès, Joaquim; Shendrik, Alexander; Bacardit Dalmases, Anna

    2011-01-01

    This paper deals with the study of the physical, chemical and biological processes associated with the deterioration of wet-white leather. The samples of leather were exposed for eight months to outdoor weathering and then their properties were subsequently evaluated. The results indicate that resistance and dimensional stability of wet-white (THPS-syntan) leather is higher than that of chrometanned leather. The comparative work with chrome leather was described earlier.

  7. Obtainment of Hg-free Mn/Zn solutions from spent alkaline batteries; Obtencion de soluciones de Mn/Zn libres de Hg provenientes de pilas alcalinas gastadas

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Nicolas, L.; Espinosa-Ramirez, I. [Instituto Politecnico Nacional, UPALM, Mexico, D.F. (Mexico)]. E-mail: lepeni@hotmail.com; Aguilar, M. [Instituto de Fisica, UNAM, Mexico, D.F. (Mexico); Palacios-Beas, E. [Instituto Politecnico Nacional, UPALM, Mexico, D.F. (Mexico)

    2009-09-15

    As in many other countries, the excessive consumption of alkaline batteries in Mexico has generated highly contaminating wastes, with heavy metal contents such as Mn, Zn, Fe, Hg, Cu and Ni, among others. This has caused a large degree of environmental degradation with repercussions for the health of living beings. Because there are no regulations regarding the disposal of spent batteries, they are thrown out with the rest of the domestic wastes or directly into nature, ending up in open-air landfills or containers where they are incinerated, thereby contaminating the planet's environment, soil and springs. The present work studies the obtainment of solutions of Hg-free Mn and Zn (Mn/Zn {>=} 1) from spent alkaline batteries for use in synthesis of (Mn,Zn)Fe{sub 2}O{sub 4} ferrite by a wet method. The effect is analyzed of the dissolution medium (H{sub 2}SO{sub 4}/H{sub 2}O{sub 2}, HCl and HCl/NO{sub 3}) temperature and time on the percentage of dissolution of the metals present in the electrode material, characterized by atomic absorption (AA) spectroscopy and x-ray diffraction (XRD). The results of the investigation indicate that the best dissolution conditions are MD=H{sub 2}SO{sub 4}/H{sub 2}O{sub 2}, T=50 degrees Celsius and t =30 min, where 94.1 and 90.7 % (w/w) of Mn and Zn are obtained, respectively, with Mn/Zn = 1.51. The mercury content was determined to be 3.91%, higher than that stated by the battery specifications, which is recovered by dissolving with HCl/HNO{sub 3} in the residual solid. [Spanish] En Mexico como en muchos otros paises, el consumo excesivo de pilas alcalinas ha generado desechos altamente contaminantes, con contenidos de metales pesados como Mn, Zn, Fe, Hg, Cu y Ni entre otros, que han provocado un gran deterioro en el medio ambiente repercutiendo en la salud de los seres vivos. Dado que no se tiene una regulacion en cuanto a la disposicion de pilas gastadas, estas se desechan con el resto de las residuos domesticos o directamente

  8. [Experimental Research of Hg (II) Removal from Aqueous Solutions of HgCl2 with Nano-TiO2].

    Science.gov (United States)

    Zhou, Xiong; Zhang, Jin-yang; Wang, Ding-yong; Qin, Cai-qing; Xu, Feng; Luo Cheng-zhong; Yang, Xi

    2016-01-15

    Mercury removal from aqueous solutions of HgCl2 was studied by indoor simulation experiments, and the effects of three different diameter of particles of Nano-TiO2 ( Nano-Titanium Dioxide) at different dosage, pH, adsorption time and the initial concentration of Hg2+ on the mercury adsorption from simulated wastewater were investigated. The single factor experiments showed that the optimal conditions were: 7.5 g x L(-1) of 5 nm TiO2 or 2.0 g x L(-1) of 100 nm TiO2, pH 8.0, initial concentration of Hg2+ 15 x mg x L(-1) adsorption time 5 min, and under these conditions the adsorption rates reached 99.5% and 99.3%, relatively. When the content of 25 nm TiO2 was 10 g x L(-1), and the other conditions were pH 8.0, initial concentration of Hg2+ 15 mg x L(-1), adsorption time 60 min, the adsorption rate was 62.8%. The Hg(II) removal effects of the TiO2 particles with different diameters followed the order of 100 nm TiO2 > 5 nm TiO2 > 25 nm TiO2. Component adsorption results showed that the 5 nm TiO2 component adsorption effect was superior to its single adsorption effect, while there was little difference between 100 nm TiO2 component adsorption effect and its single adsorption effect. The results of orthogonal experiments indicated that the influencing factors of the adsorption rate followed the order of pH > the initial concentration of Hg2+ > time > dosage. The optimal experiment scheme was: pH 8.0, a dosage of 100 nm Nano-TiO2 of 2.0 g x L(-1) an initial Hg2+ concentration of 25 mg x L(-1) and adsorption time of 10 min. Under the experimental conditions, the maximum adsorption rate reached 99.9%, at the same time, the equilibrium concentration of Hg(II) was 0.033 mg x L(-1) adsorptive capacity was 26.95 mg x g(-1). The adsorption isotherm was in line with the Langmuir isotherm equation, indicating that the Hg(II) uptake by 100 nm Nano-TiO2 was typical monolayer adsorption.

  9. Microbial communities associated with wet flue gas desulfurization systems

    Directory of Open Access Journals (Sweden)

    Bryan P. Brown

    2012-11-01

    Full Text Available Flue gas desulfurization (FGD systems are employed to remove SOx gasses that are produced by the combustion of coal for electric power generation, and consequently limit acid rain associated with these activities. Wet FGDs represent a physicochemically extreme environment due to the high operating temperatures and total dissolved solids of fluids in the interior of the FGD units. Despite the potential importance of microbial activities in the performance and operation of FGD systems, the microbial communities associated with them have not been evaluated. Microbial communities associated with distinct process points of FGD systems at several coal fired electricity generation facilities were evaluated using culture-dependent and –independent approaches. Due to the high solute concentrations and temperatures in the FGD absorber units, culturable halothermophilic/tolerant bacteria were more abundant in samples collected from within the absorber units than in samples collected from the makeup waters that are used to replenish fluids inside the absorber units. Evaluation of bacterial 16S rRNA genes recovered from scale deposits on the walls of absorber units revealed that the microbial communities associated with these deposits are primarily composed of thermophilic bacterial lineages. These findings suggest that unique microbial communities develop in FGD systems in response to physicochemical characteristics of the different process points within the systems. The activities of the thermophilic microbial communities that develop within scale deposits could play a role in the corrosion of steel structures in FGD systems.

  10. METALS DEPOSITS

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    <正>20111705 An Junbo(Team 603,Bureau of Nonferrous Metals Geological Exploration of Jilin Province,Hunchun 133300,China);Xu Renjie Geological Features and Ore Genesis of Baishilazi Scheelite Deposit in Yanbian Area(Jilin Geology,ISSN1001-2427,CN22-1099/P,29(3),2010,p.39-43,2 illus.,2 tables,7 refs.)Key words:tungsten ores,Jilin ProvinceThe Baishilazi scheelite deposit is located in contacting zone between the marble of the Late Palaeozoic Qinglongcun Group and the Hercynian biotite granite.The vein and lenticular major ore body is obviously controlled by NE-extending faults and con

  11. Improvement of Heating Method for Measuring the Wetness of Flowing Wet Steam

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    In this paper,an improvement of heating method for measuring wetness of the flowing wet steam is developed,the basic principle of the heating method is presented and the mathematical model has been built for analyzing the thermodynamics problems during the process of heating,Moreover,an instrument for measuring wetness of wet steam flow was designed and made out.This instument has been used for measuring wetness of the wet steam flow at the outlet of the nozzle rig in Thermal Turbine Laboratory,Xi'an Jiaotong University,By analyzing the relative error of the result,it was found that this instrument has fairly high accuracy,it can be used as the prototype of practical instrument and has an important applicable value in engineering.

  12. Mercury (Hg) burden in children: the impact of dental amalgam.

    Science.gov (United States)

    Al-Saleh, Iman; Al-Sedairi, Al Anoud

    2011-07-15

    The risks and benefits of using mercury (Hg) in dental amalgam have long been debated. This study was designed to estimate Hg body burden and its association with dental amalgam fillings in 182 children (ages: 5-15 years) living in Taif City. Hg was measured in urine (UHg), hair (HHg) and toenails (NHg) by the Atomic Absorption Spectrophotometer with Vapor Generator Accessory system. Urinary Hg levels were calculated as both micrograms per gram creatinine (μg/g creatinine) and micrograms per liter (μg/L). We found that children with amalgam fillings (N=106) had significantly higher UHg-C levels than children without (N=76), with means of 3.763 μg/g creatinine versus 3.457 μg/g creatinine, respectively (P=0.019). The results were similar for UHg (P=0.01). A similar pattern was also seen for HHg, with means of 0.614 μg/g (N=97) for children with amalgam versus 0.242 μg/g (N=74) for those without amalgam fillings (P=0). Although the mean NHg was higher in children without amalgam (0.222 μg/g, N=61) versus those with (0.163 μg/g, N=101), the relationship was not significant (P=0.069). After adjusting for many confounders, the multiple logistic regression model revealed that the levels of UHg-C and HHg were 2.047 and 5.396 times higher, respectively, in children with dental amalgam compared to those without (Pdental amalgam fillings (P=0.003). Despite the controversy surrounding the health impact of dental amalgam, this study showed some evidence that amalgam-associated Hg exposure might be related with symptoms of oral health, such as aphthous ulcer, white patches, and a burning-mouth sensation. Further studies are needed to reproduce these findings. The present study showed that significant numbers of children with or without amalgam had Hg levels exceeding the acceptable reference limits. The detrimental neurobehavioral and/or nephrotoxic effects of such an increased Hg on children should be a cause of concern, and further investigation is warranted. Our

  13. Crystal Growth of Solid Solution HgCdTe Alloys

    Science.gov (United States)

    Lehoczky, Sandor L.

    1997-01-01

    The growth of homogenous crystals of HgCdTe alloys is complicated by the large separation between their liquidus and solidus temperatures. Hg(1-x)Cd(x)Te is representative of several alloys which have electrical and optical properties that can be compositionally tuned for a number of applications. Limitations imposed by gravity during growth and results from growth under reduced conditions are described. The importance of residual accelerations was demonstrated by dramatic differences in compositional distribution observed for different attitudes of the space shuttle that resulted in different steady acceleration components.

  14. Natural Hg isotopic composition of different Hg compounds in mammal tissues as a proxy for in vivo breakdown of toxic methylmercury.

    Science.gov (United States)

    Perrot, Vincent; Masbou, Jeremy; Pastukhov, Mikhail V; Epov, Vladimir N; Point, David; Bérail, Sylvain; Becker, Paul R; Sonke, Jeroen E; Amouroux, David

    2016-02-01

    In the last decade, specific attention has been paid to total mercury (HgT) stable isotopic composition, especially in natural samples such as aquatic organisms, due to its potential to track the cycle of this toxic element in the environment. Here, we investigated Hg Compound Specific stable Isotopic Composition (CSIC) of natural inorganic Hg (iHg) and methylmercury (MMHg) in various tissues of aquatic mammals (Beluga whale from the Arctic marine environment and seals from the freshwater lake Baikal, Russia). In seals' organs the variation in mass dependent fractionation (MDF, δ(202)Hg) for total Hg was significantly correlated to the respective fraction of iHg and MMHg compounds, with MMHg being enriched by ∼ 3‰ in heavier isotopes relative to iHg. On the other hand, we observe insignificant variation in Hg mass independent isotope fractionation (MIF, Δ(199)Hg) among iHg and MMHg in all organs for the same mammal species and MMHg in prey items. MIF signatures suggest that both MMHg and iHg in aquatic mammals have the same origin (i.e., MMHg from food), and are representative of Hg photochemistry in the water column of the mammal ecosystem. MDF signatures of Hg compounds indicate that MMHg is demethylated in vivo before being stored in the muscle, and the iHg formed is stored in the liver, and to a lesser extent in the kidney, before excretion. Thus, Hg CSIC analysis in mammals can be a powerful tool for tracing the metabolic response to Hg exposure.

  15. The role of ELM filaments in setting the ELM wetted area in MAST and the implications for future devices

    Science.gov (United States)

    Thornton, A. J.; Allan, S. Y.; Dudson, B. D.; Elmore, S. D.; Fishpool, G. M.; Harrison, J. R.; Kirk, A.; The MAST Team; The EUROfusion MST1 Team

    2017-01-01

    The ELM wetted area is a key factor in the peak power load during an ELM, as it sets the region over which the ELM energy is deposited. The deposited heat flux at the target is seen to have striations in the profiles that are generated by the arrival of filaments ejected from the confined plasma. The effect of the filaments arriving at the target on the ELM wetted area, and the relation to the midplane mode number is investigated in this paper using infrared (IR) thermography and high speed visible imaging (>10 kHz). Type I ELMs are analysed, as these have the largest heat fluxes and are observed to have toroidal mode numbers of between 5 and 15. The IR profiles during the ELMs show clear filamentary structures that evolve during the ELM cycle. An increasing number of striations at the target is seen to correspond to an increase in the wetted area. Analysis shows that the ratio of the ELM wetted area to the inter-ELM wetted area, a key parameter for ITER, for the type I ELMs is between 3 and 6 for lower single null plasmas and varies with the ELM midplane mode number, as determined by visible measurements. Monte-Carlo modelling of the ELMs is used to understand the variation seen in the wetted area and the effect of an increased mode number; the modelling replicates the trends seen in the experimental data and supports the observation of increased toroidal mode number generating larger target ELM wetted areas. ITER is thought to be peeling unstable which would imply a lower ELM mode number compared to MAST which is peeling-ballooning unstable. The results of this analysis suggest that the lower n peeling unstable ELMs expected for ITER will have smaller wetted areas than peeling-ballooning unstable ELMs. A smaller wetted area will increase the level of ELM control required, therefore a key prediction required for ITER is the expected ELM mode number.

  16. Description and testing of three moisture sensors for measuring surface wetness on carbonate building stones

    Science.gov (United States)

    See, R.B.; Reddy, M.M.; Martin, R.G.

    1988-01-01

    Three moisture sensors were tested as a means for determining the surface wetness on carbonate building stones exposed to conditions that produce deposition of moisture. A relative-humidity probe, a gypsum-coated circuit grid, and a limestone-block resistor were tested as sensors for determining surface wetness. Sensors were tested under laboratory conditions of constant relative humidity and temperature and also under on-site conditions of variable relative humidity and temperature for eight weeks at Newcomb, NY. Laboratory tests indicated that relative humidity alone did not cause sensors to become saturated with water. However, the rates of drying indicated by the sensors after an initial saturation were inversely related to the relative humidity. On-site testing of the relative-humidity probe and the gypsum-coated ciruit grid indicated that they respond to a diurnal wetting and drying cycle; the limestone-block resistor responded only to rainfall.

  17. Activity of Cu-activated carbon fiber catalyst in wet oxidation of ammonia solution.

    Science.gov (United States)

    Hung, Chang-Mao

    2009-07-30

    Aqueous solutions of 200-1000 mg/L of ammonia were oxidized in a trickle-bed reactor using Cu-activated carbon fiber (ACF) catalysts, which were prepared by incipient wet impregnation with aqueous solutions of copper nitrate that was deposited on ACF substrates. The results reveal that the conversion of ammonia by wet oxidation in the presence of Cu-ACF catalysts was a function of the metal loading weight ratio of the catalyst. The total conversion efficiency of ammonia was 95% during wet oxidation over the catalyst at 463 K at an oxygen partial pressure of 3.0 MPa. Moreover, the effect of the initial concentration of ammonia and the reaction temperature on the removal of ammonia from the effluent streams was also studied at a liquid space velocity of less than 3.0 h(-1).

  18. METALS DEPOSITS

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    <正>20090243 Chen Zhibin (Hebei Institute of Geological Survey, Shijiazhuang 050081, China) Ore-Controlling Factors of the Beichagoumen Ag-Polymetallic Deposits in Northern Hebei Province (Geological Survey and Research, ISSN1672-4135, CN12-1353/P, 31(1), 2008, p.1-5, 3 illus., 10 refs.)

  19. METALS DEPOSITS

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    <正>20131565 Cai Lianyou(No.332 Geological Team,Bureau of Geology and Mineral Resources Exploration of Anhui Province,Huangshan 245000,China);Weng Wangfei Geological Characteristics and Genesis Analysis of Guocun Navajoite Deposit in South Anhui Province(Mineral Resources and Geology,

  20. METALS DEPOSITS

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    <正>20102341 Bao Peisheng(Institute of Geology,Chinese Academy of Geological Science,Beijing 100037,China)Further Discussion on the Genesis of the Podiform Chromite Deposits in the Ophiolites-Questioning about the Rock:Melt Interaction Metallogeny(Geological Bulletin of China,ISSN1671-2552,CN11-4648/P,28(12),2009,p.1741-1761

  1. NONMETALS DEPOSITS

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    <正>20131601 Gao Junbo(College of Resources and Environmental Engineering,Guizhou University,Guiyang 550003,China);Yang Ruidong Hydrothermal Venting-Flowing Sedimentation Characteristics of Devonian Barite Deposits from Leji,Zhenning County,Guizhou Province(Acta Sedimentologica Sinica,ISSN1000-0550,CN62-1038/P,30(3),

  2. Atmospheric chemistry of mercury in Antarctica and the role of cryptogams to assess deposition patterns in coastal ice-free areas.

    Science.gov (United States)

    Bargagli, R

    2016-11-01

    Mercury in the Antarctic troposphere has a distinct chemistry and challenging long-term measurements are needed for a better understanding of the atmospheric Hg reactions with oxidants and the exchanges of the various mercury forms among air-snow-sea and biota. Antarctic mosses and lichens are reliable biomonitors of airborne metals and in short time they can give useful information about Hg deposition patterns. Data summarized in this review show that although atmospheric Hg concentrations in the Southern Hemisphere are lower than those in the Northern Hemisphere, Antarctic cryptogams accumulate Hg at levels in the same range or higher than those observed for related cryptogam species in the Arctic, suggesting an enhanced deposition of bioavailable Hg in Antarctic coastal ice-free areas. In agreement with the newest findings in the literature, the Hg bioaccumulation in mosses and lichens from a nunatak particularly exposed to strong katabatic winds can be taken as evidence for a Hg contribution to coastal ecosystems by air masses from the Antarctic plateau. Human activities on the continent are mostly concentrated in coastal ice-free areas, and the deposition in these areas of Hg from the marine environment, the plateau and anthropogenic sources raises concern. The use of Antarctic cryptogams as biomonitors will be very useful to map Hg deposition patterns in costal ice-free areas and will contribute to a better understanding of Hg cycling in Antarctica and its environmental fate in terrestrial ecosystems.

  3. Significant interaction effects from sulfate deposition and climate on sulfur concentrations constitute major controls on methylmercury production in peatlands

    Science.gov (United States)

    Åkerblom, Staffan; Bishop, Kevin; Björn, Erik; Lambertsson, Lars; Eriksson, Tobias; Nilsson, Mats B.

    2013-02-01

    Transformation of inorganic mercury (Hg) to methyl mercury (MeHg) in peatlands is a key process in making boreal catchments a source of MeHg</