WorldWideScience

Sample records for carbon efflux estimates

  1. Calibration and analysis of soil carbon efflux estimates with closed chambers at Forsmark and Laxemar

    Energy Technology Data Exchange (ETDEWEB)

    Tagesson, Torbern (Dept. of Physical Geography and Ecosystem Analysis, Lund Univ., Lund (SE))

    2006-08-15

    The Forsmark and the Laxemar investigation areas are examined by the Swedish Nuclear Fuel and Waste Management Co. for a possible construction of a deep repository for nuclear waste. In the case of a future leakage of waste, the radioactive isotopes could end up in the ecosystems above the repository. The fate of the radionuclides and their possible radiological impacts are then highly determined by ecosystem carbon cycling. An important part of the carbon cycling is the soil carbon effluxes, and in the investigation areas soil carbon effluxes have been examined with the closed chamber technique. This paper is divided into two parts. Firstly, there were problems with the equipment measuring the soil carbon dioxide efflux, and the first part is a description of the problem, how it was corrected and its possible causes. The second part is a manual in how to analyse data and calculate annual estimates of soil carbon efflux. The field measurement by the EGM-4 is just an occasional estimate of the soil carbon efflux at a certain spot and at a certain point in time. To make an interpretation of the measurements, it is essential to analyse the data and to temporally extrapolate them. It is necessary to prepare the raw data for the analysis. The problems with the EGM-4 doing the measurements at the Forsmark and the Laxemar investigation area makes it necessary to correct the data taken up by this EGM-4. The data should also be separated into soil respiration and gross primary production (GPP). Soil carbon dioxide effluxes should be changed to soil carbon effluxes. Soil carbon effluxes are strongly controlled by abiotic factors; temperature is the main factor to influence soil respiration and photosynthetically active radiation (PAR) and air temperature are the main factors to influence GPP. Regression with soil respiration against temperature and with GPP against PAR or temperature can therefore be done. These equations can then be used on datasets with temperature and PAR

  2. Calibration and analysis of soil carbon efflux estimates with closed chambers at Forsmark and Laxemar

    International Nuclear Information System (INIS)

    Tagesson, Torbern

    2006-08-01

    The Forsmark and the Laxemar investigation areas are examined by the Swedish Nuclear Fuel and Waste Management Co. for a possible construction of a deep repository for nuclear waste. In the case of a future leakage of waste, the radioactive isotopes could end up in the ecosystems above the repository. The fate of the radionuclides and their possible radiological impacts are then highly determined by ecosystem carbon cycling. An important part of the carbon cycling is the soil carbon effluxes, and in the investigation areas soil carbon effluxes have been examined with the closed chamber technique. This paper is divided into two parts. Firstly, there were problems with the equipment measuring the soil carbon dioxide efflux, and the first part is a description of the problem, how it was corrected and its possible causes. The second part is a manual in how to analyse data and calculate annual estimates of soil carbon efflux. The field measurement by the EGM-4 is just an occasional estimate of the soil carbon efflux at a certain spot and at a certain point in time. To make an interpretation of the measurements, it is essential to analyse the data and to temporally extrapolate them. It is necessary to prepare the raw data for the analysis. The problems with the EGM-4 doing the measurements at the Forsmark and the Laxemar investigation area makes it necessary to correct the data taken up by this EGM-4. The data should also be separated into soil respiration and gross primary production (GPP). Soil carbon dioxide effluxes should be changed to soil carbon effluxes. Soil carbon effluxes are strongly controlled by abiotic factors; temperature is the main factor to influence soil respiration and photosynthetically active radiation (PAR) and air temperature are the main factors to influence GPP. Regression with soil respiration against temperature and with GPP against PAR or temperature can therefore be done. These equations can then be used on datasets with temperature and PAR

  3. Organic carbon efflux from a deciduous forest catchment in Korea

    Directory of Open Access Journals (Sweden)

    S. J. Kim

    2010-04-01

    Full Text Available Soil infiltration and surface discharge of precipitation are critical processes that affect the efflux of Dissolved Organic Carbon (DOC and Particulate Organic Carbon (POC in forested catchments. Concentrations of DOC and POC can be very high in the soil surface in most forest ecosystems and their efflux may not be negligible particularly under the monsoon climate. In East Asia, however, there are little data available to evaluate the role of such processes in forest carbon budget. In this paper, we address two basic questions: (1 how does stream discharge respond to storm events in a forest catchment? and (2 how much DOC and POC are exported from the catchment particularly during the summer monsoon period? To answer these questions, we collected hydrological data (e.g., precipitation, soil moisture, runoff discharge, groundwater level and conducted hydrochemical analyses (including DOC, POC, and six tracers in a deciduous forest catchment in Gwangneung National Arboretum in west-central Korea. Based on the end-member mixing analysis of the six storm events during the summer monsoon in 2005, the surface discharge was estimated as 30 to 80% of the total runoff discharge. The stream discharge responded to precipitation within 12 h during these storm events. The annual efflux of DOC and POC from the catchment was estimated as 0.04 and 0.05 t C ha−1 yr−1, respectively. Approximately 70% of the annual organic carbon efflux occurred during the summer monsoon period. Overall, the annual efflux of organic carbon was estimated to be about 10% of the Net Ecosystem carbon Exchange (NEE obtained by eddy covariance measurement at the same site. Considering the current trends of increasing intensity and amount of summer rainfall and the large interannual variability in NEE, ignoring the organic carbon efflux from forest catchments would result in an inaccurate estimation of the carbon sink strength of forest ecosystems in the monsoon

  4. Hydrodynamic Controls on Carbon Dioxide Efflux from Inland Waters

    Science.gov (United States)

    Long, H. E.; Waldron, S.; Hoey, T.; Newton, J.; Quemin, S.

    2013-12-01

    Intensive research has been undertaken on carbon dioxide efflux from lakes, estuaries and oceans, but much less attention has been given to rivers and streams, especially lower order streams. River systems are often over-saturated with carbon dioxide and so tend to act as sources of carbon dioxide to the atmosphere. It has been thought that rivers act as pipes carrying this terrestrial carbon to the oceans. However, recent studies have shown that a significant amount of the carbon is reprocessed within the system in a series of transformations and losses. Fluvial evasion of carbon dioxide is now recognised to be a significant component of carbon cycles, however the factors controlling carbon dioxide efflux and its magnitude remain poorly understood and quantified. This research aims to quantify, and better understand the controls on, freshwater carbon dioxide evasion. Data are presented here from field measurements that commenced in Sept 2013 in two contrasting Scottish rivers: the River Kelvin which has a large (335 km.sq) part-urban catchment with predominantly non-peat soils and Drumtee Water, a small (9.6 km.sq) rural catchment of peat soils and agricultural land. Using a floating chamber with the headspace connected to an infrared gas analyser to measure changes in carbon dioxide concentration, efflux rates from 0.22 - 47.4 μmol CO2/m.sq/sec were measured, these close to the middle of the range of previously reported values. At one site on the River Kelvin in May 2013 an influx of -0.61 - -3.53 μmol CO2/m.sq/sec was recorded. Whereas previous research finds carbon dioxide efflux to increase with decreasing river size and a more organic-rich soil catchment, here the controls on carbon dioxide evasion are similar across the contrasting catchments. Carbon dioxide evasion shows seasonality, with maximum fluxes in the summer months being up to twice as high as the winter maxima. Linear regression demonstrates that evasion increases with increased flow velocity

  5. Soil carbon effluxes in ecosystems of Forsmark and Laxemar

    Energy Technology Data Exchange (ETDEWEB)

    Tagesson, Torbern (Dept. of Physical Geography and Ecosystem Analysis, Lund Univ. (Sweden))

    2007-12-15

    Soil carbon effluxes were estimated in a number of ecosystems in Laxemar and Forsmark investigations areas. It was done in a young Scots pine (Pinus sylvestris) stand, a wet deciduous stand, a poor fen and an agricultural field in the Laxemar investigation area in south-eastern Sweden (57 deg 5 min N, 16 deg 7 min E) and in a pasture, two Norway spruce (Picea abies) stands, a deciduous forest, a mire, a wet deciduous forest and a clear-cut in the Forsmark investigation area (60 deg 4 min N, 18 deg 2 min E). It was measured with the closed chamber technique in 2005 and 2006. Soil temperature at 10 cm depth, air temperature and photosynthetically active radiation (PAR) were also measured. Exponential regressions with soil respiration against air and soil temperature were used to estimate annual soil respiration. A hyperbolic curve with Gross Primary Production (GPP) against PAR was used for modelling GPP for the growing season in the poor fen and the agricultural area of Laxemar. The exponential regressions with soil respiration against air and soil temperature explained on average 33.6% and 44.0% of the variation, respectively. GPP of the ground vegetation were reducing soil carbon effluxes, in all stands but one of the spruce stands, the deciduous forest, the mire and the wet deciduous forest of Forsmark. The significant (all but spruce 2 in Forsmark) curves with GPP against PAR explained on average 22.7% of the variation in GPP. The cubic regressions with GPP against air temperature were only significant for the poor fen and the agricultural field in Laxemar and it explained on average 34.8% of the variation in GPP for these ecosystems. The exponential regressions with air and soil temperature against soil respiration could be used to temporally extrapolate the occasional field measurements. The hyperbolic curve with GPP against PAR could also be used for temporal extrapolation of GPP for the ecosystems without a tree layer, i.e. the poor fen and the agricultural

  6. Soil carbon effluxes in ecosystems of Forsmark and Laxemar

    International Nuclear Information System (INIS)

    Tagesson, Torbern

    2007-12-01

    Soil carbon effluxes were estimated in a number of ecosystems in Laxemar and Forsmark investigations areas. It was done in a young Scots pine (Pinus sylvestris) stand, a wet deciduous stand, a poor fen and an agricultural field in the Laxemar investigation area in south-eastern Sweden (57 deg 5 min N, 16 deg 7 min E) and in a pasture, two Norway spruce (Picea abies) stands, a deciduous forest, a mire, a wet deciduous forest and a clear-cut in the Forsmark investigation area (60 deg 4 min N, 18 deg 2 min E). It was measured with the closed chamber technique in 2005 and 2006. Soil temperature at 10 cm depth, air temperature and photosynthetically active radiation (PAR) were also measured. Exponential regressions with soil respiration against air and soil temperature were used to estimate annual soil respiration. A hyperbolic curve with Gross Primary Production (GPP) against PAR was used for modelling GPP for the growing season in the poor fen and the agricultural area of Laxemar. The exponential regressions with soil respiration against air and soil temperature explained on average 33.6% and 44.0% of the variation, respectively. GPP of the ground vegetation were reducing soil carbon effluxes, in all stands but one of the spruce stands, the deciduous forest, the mire and the wet deciduous forest of Forsmark. The significant (all but spruce 2 in Forsmark) curves with GPP against PAR explained on average 22.7% of the variation in GPP. The cubic regressions with GPP against air temperature were only significant for the poor fen and the agricultural field in Laxemar and it explained on average 34.8% of the variation in GPP for these ecosystems. The exponential regressions with air and soil temperature against soil respiration could be used to temporally extrapolate the occasional field measurements. The hyperbolic curve with GPP against PAR could also be used for temporal extrapolation of GPP for the ecosystems without a tree layer, i.e. the poor fen and the agricultural

  7. Carbon dioxide efflux from leaves in light and darkness

    Energy Technology Data Exchange (ETDEWEB)

    Holmgren, P; Jarvis, P G

    1967-01-01

    The efflux of carbon dioxide in light and darkness was measured at low ambient CO/sub 2/ concentrations in leaves of Rumex acetosa. Light carbon dioxide production (photorespiration) was found to depend on irradiance and to differ from dark production as to the response to temperature and ambient concentrations of O/sub 2/ and CO/sub 2/. These observations support previously made suggestions that photorespiration follows a different metabolic pathway to dark respiration.

  8. Old carbon efflux from tropical peat swamp drainage waters

    Science.gov (United States)

    Vihermaa, Leena; Waldron, Susan; Evers, Stephanie; Garnett, Mark; Newton, Jason

    2014-05-01

    Tropical peatlands constitute ~12% of the global peatland carbon pool, and of this 10% is in Malaysia1. Due to rising demand for food and biofuels, large areas of peat swamp forest ecosystems have been converted to plantation in Southeast Asia and are being subjected to degradation, drainage and fire, changing their carbon fluxes eg.2,3. Dissolved organic carbon (DOC) lost from disturbed tropical peat can be derived from deep within the peat column and be aged from centuries to millennia4 contributing to aquatic release and cycling of old carbon. Here we present the results of a field campaign to the Raja Musa Peat Swamp Forest Reserve in N. Selangor Malaysia, which has been selectively logged for 80 years before being granted timber reserve status. We measured CO2 and CH4efflux rates from drainage systems with different treatment history, and radiocarbon dated the evasion CO2 and associated [DOC]. We also collected water chemistry and stable isotope data from the sites. During our sampling in the dry season CO2 efflux rates ranged from 0.8 - 13.6 μmol m-2 s-1. Sediments in the channel bottom contained CH4 that appeared to be primarily lost by ebullition, leading to sporadic CH4 efflux. However, dissolved CH4 was also observed in water samples collected from these systems. The CO2 efflux was aged up to 582±37 years BP (0 BP = AD 1950) with the associated DOC aged 495±35 years BP. Both DOC and evasion CO2 were most 14C-enriched (i.e. younger) at the least disturbed site, and implied a substantial component of recently fixed carbon. In contrast, CO2 and DOC from the other sites had older 14C ages, indicating disturbance as the trigger for the loss of old carbon. 1Page et al., 2010 2Hooijer et al., 2010 3Kimberly et al., 2012 4Moore et al., 2013

  9. Soil carbon dioxide (CO 2 ) efflux of two shrubs in response to plant ...

    African Journals Online (AJOL)

    Although plant density should affect soil carbon dioxide (CO2) efflux and carbon cycling in semi-arid regions, the effects of plant density on soil CO2 efflux are not well known. This study was performed to investigate the responses of soil CO2 efflux of two dominant shrubs (Caragana korshinkii and Salix psammophila) to ...

  10. Contrasting effects of repeated summer drought on soil carbon efflux in hydric and mesic heathland soils

    NARCIS (Netherlands)

    Sowerby, A.; Emmett, B.A.; Tietema, A.; Beier, C.

    2008-01-01

    Current predictions of climate change include altered rainfall patterns throughout Europe, continental USA and areas such as the Amazon. The effect of this on soil carbon efflux remains unclear although several modelling studies have highlighted the potential importance of drought for carbon

  11. Impact of grazing intensity on seasonal variations in soil organic carbon and soil CO2 efflux in two semiarid grasslands in southern Botswana

    Science.gov (United States)

    Thomas, Andrew D.

    2012-01-01

    Biological soil crusts (BSCs) are an important source of organic carbon, and affect a range of ecosystem functions in arid and semiarid environments. Yet the impact of grazing disturbance on crust properties and soil CO2 efflux remain poorly studied, particularly in African ecosystems. The effects of burial under wind-blown sand, disaggregation and removal of BSCs on seasonal variations in soil CO2 efflux, soil organic carbon, chlorophyll a and scytonemin were investigated at two sites in the Kalahari of southern Botswana. Field experiments were employed to isolate CO2 efflux originating from BSCs in order to estimate the C exchange within the crust. Organic carbon was not evenly distributed through the soil profile but concentrated in the BSC. Soil CO2 efflux was higher in Kalahari Sand than in calcrete soils, but rates varied significantly with seasonal changes in moisture and temperature. BSCs at both sites were a small net sink of C to the soil. Soil CO2 efflux was significantly higher in sand soils where the BSC was removed, and on calcrete where the BSC was buried under sand. The BSC removal and burial under sand also significantly reduced chlorophyll a, organic carbon and scytonemin. Disaggregation of the soil crust, however, led to increases in chlorophyll a and organic carbon. The data confirm the importance of BSCs for C cycling in drylands and indicate intensive grazing, which destroys BSCs through trampling and burial, will adversely affect C sequestration and storage. Managed grazing, where soil surfaces are only lightly disturbed, would help maintain a positive carbon balance in African drylands. PMID:23045706

  12. Nitrogen fertilization raises CO2 efflux from inorganic carbon: A global assessment.

    Science.gov (United States)

    Zamanian, Kazem; Zarebanadkouki, Mohsen; Kuzyakov, Yakov

    2018-03-25

    Nitrogen (N) fertilization is an indispensable agricultural practice worldwide, serving the survival of half of the global population. Nitrogen transformation (e.g., nitrification) in soil as well as plant N uptake releases protons and increases soil acidification. Neutralizing this acidity in carbonate-containing soils (7.49 × 10 9  ha; ca. 54% of the global land surface area) leads to a CO 2 release corresponding to 0.21 kg C per kg of applied N. We here for the first time raise this problem of acidification of carbonate-containing soils and assess the global CO 2 release from pedogenic and geogenic carbonates in the upper 1 m soil depth. Based on a global N-fertilization map and the distribution of soils containing CaCO 3 , we calculated the CO 2 amount released annually from the acidification of such soils to be 7.48 × 10 12  g C/year. This level of continuous CO 2 release will remain constant at least until soils are fertilized by N. Moreover, we estimated that about 273 × 10 12  g CO 2 -C are released annually in the same process of CaCO 3 neutralization but involving liming of acid soils. These two CO 2 sources correspond to 3% of global CO 2 emissions by fossil fuel combustion or 30% of CO 2 by land-use changes. Importantly, the duration of CO 2 release after land-use changes usually lasts only 1-3 decades before a new C equilibrium is reached in soil. In contrast, the CO 2 released by CaCO 3 acidification cannot reach equilibrium, as long as N fertilizer is applied until it becomes completely neutralized. As the CaCO 3 amounts in soils, if present, are nearly unlimited, their complete dissolution and CO 2 release will take centuries or even millennia. This emphasizes the necessity of preventing soil acidification in N-fertilized soils as an effective strategy to inhibit millennia of CO 2 efflux to the atmosphere. Hence, N fertilization should be strictly calculated based on plant-demand, and overfertilization should be avoided not only

  13. Variations in soil carbon dioxide efflux across a thaw slump chronosequence in northwestern Alaska

    International Nuclear Information System (INIS)

    Jensen, A E; Crosby, B T; Lohse, K A; Mora, C I

    2014-01-01

    Warming of the arctic landscape results in permafrost thaw, which causes ground subsidence or thermokarst. Thermokarst formation on hillslopes leads to the formation of thermal erosion features that dramatically alter soil properties and likely affect soil carbon emissions, but such features have received little study in this regard. In order to assess the magnitude and persistence of altered emissions, we use a space-for-time substitution (thaw slump chronosequence) to quantify and compare peak growing season soil carbon dioxide (CO 2 ) fluxes from undisturbed tundra, active, and stabilized thermal erosion features over two seasons. Measurements of soil temperature and moisture, soil organic matter, and bulk density are used to evaluate the factors controlling soil CO 2 emissions from each of the three chronosequence stages. Soil CO 2 efflux from the active slump is consistently less than half that observed in the undisturbed tundra or stabilized slump (1.8 versus 5.2 g CO 2 −C m −2  d −1 in 2011; 0.9 versus 3.2 g CO 2 −C m −2  d −1 in 2012), despite soil temperatures on the floor of the active slump that are 10–15  ° C warmer than the tundra and stabilized slump. Environmental factors such as soil temperature and moisture do not exert a strong control on CO 2 efflux, rather, local soil physical and chemical properties such as soil organic matter and bulk density, are strongly and inversely related among these chronosequence stages (r 2 = 0.97), and explain ∼50% of the variation in soil CO 2 efflux. Thus, despite profound soil warming and rapid exposure of buried carbon in the active slump, the low organic matter content, lack of stable vegetation, and large increases in the bulk densities in the uppermost portion of active slump soils (up to ∼2.2 g −1  cm −3 ) appear to limit CO 2 efflux from the active slump. Future studies should assess seasonal fluxes across these features and determine whether soil CO 2 fluxes from active

  14. Seasonal variation and controlling factors of soil carbon effluxes in six vegetation types in southeast of Sweden

    Energy Technology Data Exchange (ETDEWEB)

    Tagesson, Torbern (Dept. of Physical Geography and Ecosystem Analysis, Lund Univ., Lund (SE))

    2007-11-15

    Soil carbon effluxes of a pine stand, a spruce stand, a lichen rock, two oak stands and a meadow in the Laxemar investigation area in south-eastern Sweden (57 deg 5 N, 16 deg 7 E) have been measured with the closed chamber technique at 14 occasions between 23 of March 2004 and 10th of March 2005. Soil temperature at 10 cm depth, air temperature, soil moisture and photosynthetically active radiation (PAR) were also measured. Exponential regressions with soil respiration against air and soil temperature were used to estimate soil respiration between 15th of March 2004 and 14th of March 2005. A light response curve with Gross Primary Production (GPP) against PAR and a cubic regression with GPP against air temperature were used for modelling GPP in meadow for the growing season, 15th of March to 31st of October 2004. The exponential regressions with soil respiration against air and soil temperature explained on average 30.6% and 47.6% of the variation, respectively. Soil moisture had a linear limiting effect on soil respiration for all ecosystems but spruce, where soil moisture was the limiting factor above a threshold value of about 50%vol. In the forest ecosystems, GPP of the ground vegetation were not reducing soil carbon effluxes, while in meadow it was. In meadow, the light response curve with GPP against PAR explained 32.7% of the variation in GPP while the cubic regression against air temperature explained 33.9%. No significant effect of soil moisture on GPP was detected. The exponential regression equations with air and soil temperature against soil respiration could be used to temporally extrapolate the occasional field measurements. The light response curve with GPP against PAR and the cubic regression with GPP against air temperature could also be used for temporal extrapolation. From the modelled soil respiration, annual soil respiration for the ecosystems in Laxemar, during 15th of March 2004 to 14th of March 2005, were estimated to be between 0.56 and 1

  15. Seasonal variation and controlling factors of soil carbon effluxes in six vegetation types in southeast of Sweden

    International Nuclear Information System (INIS)

    Tagesson, Torbern

    2007-11-01

    Soil carbon effluxes of a pine stand, a spruce stand, a lichen rock, two oak stands and a meadow in the Laxemar investigation area in south-eastern Sweden (57 deg 5 N, 16 deg 7 E) have been measured with the closed chamber technique at 14 occasions between 23 of March 2004 and 10th of March 2005. Soil temperature at 10 cm depth, air temperature, soil moisture and photosynthetically active radiation (PAR) were also measured. Exponential regressions with soil respiration against air and soil temperature were used to estimate soil respiration between 15th of March 2004 and 14th of March 2005. A light response curve with Gross Primary Production (GPP) against PAR and a cubic regression with GPP against air temperature were used for modelling GPP in meadow for the growing season, 15th of March to 31st of October 2004. The exponential regressions with soil respiration against air and soil temperature explained on average 30.6% and 47.6% of the variation, respectively. Soil moisture had a linear limiting effect on soil respiration for all ecosystems but spruce, where soil moisture was the limiting factor above a threshold value of about 50%vol. In the forest ecosystems, GPP of the ground vegetation were not reducing soil carbon effluxes, while in meadow it was. In meadow, the light response curve with GPP against PAR explained 32.7% of the variation in GPP while the cubic regression against air temperature explained 33.9%. No significant effect of soil moisture on GPP was detected. The exponential regression equations with air and soil temperature against soil respiration could be used to temporally extrapolate the occasional field measurements. The light response curve with GPP against PAR and the cubic regression with GPP against air temperature could also be used for temporal extrapolation. From the modelled soil respiration, annual soil respiration for the ecosystems in Laxemar, during 15th of March 2004 to 14th of March 2005, were estimated to be between 0.56 and 1

  16. Winter carbon dioxide effluxes from Arctic ecosystems: An overview and comparison of methodologies

    DEFF Research Database (Denmark)

    Björkman, M.P.; Morgner, E.; Cooper, E.J.

    2010-01-01

    removal, (3) diffusion measurements, F2-point, within the snowpack, and (4) a trace gas technique, FSF6, with multiple gas sampling within the snowpack. According to measurements collected from shallow and deep snow cover in High Arctic Svalbard and subarctic Sweden during the winter of 2007......The winter CO2 efflux from subnivean environments is an important component of annual C budgets in Arctic ecosystems and consequently makes prediction and estimations of winter processes as well as incorporations of these processes into existing models important. Several methods have been used......, Fsoil is assumed to measure soil production, whereas FSF6, Fsnow, and F2-point are considered better approaches for quantifying exchange processes between the soil, snow, and the atmosphere. This study indicates that estimates of winter CO2 emissions may vary more as a result of the method used than...

  17. Carbon dioxide effluxes and their environmental controls in sagebrush steppe ecosystems along an elevation gradient in the Reynolds Creek Critical Zone Observatory

    Science.gov (United States)

    Lohse, K. A.; Fellows, A.; Flerchinger, G. N.; Seyfried, M. S.

    2017-12-01

    The spatial and temporal variation of carbon dioxide effluxes and their environmental controls are poorly constrained in cold shrub steppe ecosystems. The objectives of this study were to 1) analyze environmental parameters in determining soil CO2 efflux, 2) assess the level of agreement between manual chambers and force diffusion (FD) soil CO2 efflux chambers, when both measurements are extrapolated across the growing season, and lastly to compare respiration fluxes to modeled ecosystem respiration fluxes. We installed FD chambers at four sites co-located with eddy covariance (EC) towers and soil moisture and temperature sensors along an elevation gradient in the Reynolds Creek Critical Zone Observatory in SW Idaho. FD chamber fluxes were collected continuously at 15-minute intervals. We sampled soil CO2 efflux with manual chambers at plant and interplant spaces in five plots at each site biweekly to monthly during the growing season. The sites included a Wyoming big sagebrush site, a low sagebrush site, a post-fire mountain big sagebrush site, and a mountain big sagebrush site located at elevations of 1425, 1680, 1808 and 2111 m. Climate variation followed the montane elevation gradient; mean annual precipitation (MAP) at the sites is 290, 337, 425, and 795 mm, respectively, and mean annual temperature is 8.9, 8.4, 6.1, 5.4°C. Automated force diffusion chambers detected large differences in carbon dioxide pulse dynamics along the elevation gradient. Growing season carbon dioxide fluxes were 3 times higher at the 425 mm MAP site compared than the lowest elevation sites at 290 and 337 MAP sites and >1.5 higher than the 795 mm MAP site over the same period. Manual fluxes showed similar seasonal patterns as FD chamber fluxes but often higher and greater spatial variability in fluxes than FD chamber fluxes. Plant and interplant flux differences were surprisingly similar, especially at higher elevations. Soil respiration ranged from 0.2-0.48 of ecosystem respiration

  18. Carbon dioxide efflux from a 550 m3 soil across a range of soul temperatues

    Science.gov (United States)

    Ramesh Murthy; Kevin L. Griffin; Stanley J. Zarnoch; Philip M. Dougherty; Barbara Watson; Joost Van Haren; Randy L. Patterson; Tilka Mahato

    2003-01-01

    Because of scaling problems point measurements of soil CO2 efflux on a small volume of soil may not necessarily reflect an overall community response. The aim of this study was to test this hypothesis in the Biosphere 2 facility and achieve the following broad goals: (1) investigate soil net CO2 exchange–temperature...

  19. Biases of chamber methods for measuring soil CO2 efflux demonstrated with a laboratory apparatus.

    Science.gov (United States)

    S. Mark Nay; Kim G. Mattson; Bernard T. Bormann

    1994-01-01

    Investigators have historically measured soil CO2 efflux as an indicator of soil microbial and root activity and more recently in calculations of carbon budgets. The most common methods estimate CO2 efflux by placing a chamber over the soil surface and quantifying the amount of CO2 entering the...

  20. Influence of high-frequency ambient pressure pumping on carbon dioxide efflux from soil

    Science.gov (United States)

    Eugene S. Takle; William J. Massman; James R. Brandle; R. A. Schmidt; Xinhua Zhou; Irina V. Litvina; Rick Garcia; Geoffrey Doyle; Charles W. Rice

    2004-01-01

    We report measurements at 2Hz of pressure fluctuations at and beneath the soil in an agricultural field with dry soil and no vegetation. The objective of our study was to examine the possible role of pressure fluctuations produced by fluctuations in ambient wind on the efflux of CO2 at the soil surface.We observed that pressure fluctuations penetrate to 50 cm in the...

  1. Contrasting effects of repeated summer drought on soil carbon efflux in hydric and mesic heathland soils

    DEFF Research Database (Denmark)

    Sowerby, Alwyn; Emmett, Bridget A.; Tietema, Albert

    2008-01-01

    storage. To test the importance of drought, and more importantly repeated drought year-on-year, we used automated retractable curtains to exclude rain and produce repeated summer drought in three heathlands at varying moisture conditions. This included a hydric system limited by water-excess (in the UK...... and DK sites during the winter re-wetting period that indicates any change in soil C storage due to changes in soil C efflux may be short lived in these mesic systems. In contrast, in the hydric UK site after 2 years of drought treatment, the persistent reduction in soil moisture throughout the year...

  2. CO2 efflux from cleared mangrove peat.

    Directory of Open Access Journals (Sweden)

    Catherine E Lovelock

    Full Text Available CO(2 emissions from cleared mangrove areas may be substantial, increasing the costs of continued losses of these ecosystems, particularly in mangroves that have highly organic soils.We measured CO(2 efflux from mangrove soils that had been cleared for up to 20 years on the islands of Twin Cays, Belize. We also disturbed these cleared peat soils to assess what disturbance of soils after clearing may have on CO(2 efflux. CO(2 efflux from soils declines from time of clearing from ∼10,600 tonnes km(-2 year(-1 in the first year to 3000 tonnes km(2 year(-1 after 20 years since clearing. Disturbing peat leads to short term increases in CO(2 efflux (27 umol m(-2 s(-1, but this had returned to baseline levels within 2 days.Deforesting mangroves that grow on peat soils results in CO(2 emissions that are comparable to rates estimated for peat collapse in other tropical ecosystems. Preventing deforestation presents an opportunity for countries to benefit from carbon payments for preservation of threatened carbon stocks.

  3. Soil properties differently influence estimates of soil CO2 efflux from three chamber-based measurement systems

    Science.gov (United States)

    John R. Butnor; Kurt H. Johnsen; Chris A. Maier

    2005-01-01

    Soil C02 efflux is a major component of net ecosystem productivity (NEP) of forest systems. Combining data from multiple researchers for larger-scale modeling and assessment will only be valid if their methodologies provide directly comparable results. We conducted a series of laboratory and field tests to assess the presence and magnitude of...

  4. Carbon storage, soil carbon dioxide efflux and water quality in three widths of piedmont streamside management zones

    Science.gov (United States)

    Erica F. Wadl; William Lakel; Michael Aust; John Seiler

    2010-01-01

    Streamside management zones (SMZs) are used to protect water quality. Monitoring carbon pools and fluxes in SMZs may a good indicator of the SMZ’s overall function and health. In this project we evaluated some of these pools and fluxes from three different SMZ widths (30.5, 15.3, and 7.6 m) in the Piedmont of Virginia. We quantified carbon storage in the soil (upper 10...

  5. CO₂ efflux from shrimp ponds in Indonesia.

    Science.gov (United States)

    Sidik, Frida; Lovelock, Catherine E

    2013-01-01

    The conversion of mangrove forest to aquaculture ponds has been increasing in recent decades. One of major concerns of this habitat loss is the release of stored 'blue' carbon from mangrove soils to the atmosphere. In this study, we assessed carbon dioxide (CO₂) efflux from soil in intensive shrimp ponds in Bali, Indonesia. We measured CO₂ efflux from the floors and walls of shrimp ponds. Rates of CO₂ efflux within shrimp ponds were 4.37 kg CO₂ m⁻² y⁻¹ from the walls and 1.60 kg CO₂ m⁻² y⁻¹ from the floors. Combining our findings with published data of aquaculture land use in Indonesia, we estimated that shrimp ponds in this region result in CO₂ emissions to the atmosphere between 5.76 and 13.95 Tg y⁻¹. The results indicate that conversion of mangrove forests to aquaculture ponds contributes to greenhouse gas emissions that are comparable to peat forest conversion to other land uses in Indonesia. Higher magnitudes of CO₂ emission may be released to atmosphere where ponds are constructed in newly cleared mangrove forests. This study indicates the need for incentives that can meet the target of aquaculture industry without expanding the converted mangrove areas, which will lead to increased CO₂ released to atmosphere.

  6. CO₂ efflux from shrimp ponds in Indonesia.

    Directory of Open Access Journals (Sweden)

    Frida Sidik

    Full Text Available The conversion of mangrove forest to aquaculture ponds has been increasing in recent decades. One of major concerns of this habitat loss is the release of stored 'blue' carbon from mangrove soils to the atmosphere. In this study, we assessed carbon dioxide (CO₂ efflux from soil in intensive shrimp ponds in Bali, Indonesia. We measured CO₂ efflux from the floors and walls of shrimp ponds. Rates of CO₂ efflux within shrimp ponds were 4.37 kg CO₂ m⁻² y⁻¹ from the walls and 1.60 kg CO₂ m⁻² y⁻¹ from the floors. Combining our findings with published data of aquaculture land use in Indonesia, we estimated that shrimp ponds in this region result in CO₂ emissions to the atmosphere between 5.76 and 13.95 Tg y⁻¹. The results indicate that conversion of mangrove forests to aquaculture ponds contributes to greenhouse gas emissions that are comparable to peat forest conversion to other land uses in Indonesia. Higher magnitudes of CO₂ emission may be released to atmosphere where ponds are constructed in newly cleared mangrove forests. This study indicates the need for incentives that can meet the target of aquaculture industry without expanding the converted mangrove areas, which will lead to increased CO₂ released to atmosphere.

  7. Nocturnal carbon efflux: reconciliation of eddy covariance and chamber measurements using an alternative to the u*-threshold filtering technique

    International Nuclear Information System (INIS)

    Gorsel, Eva Van.; Leuning, Ray; Cleugh, Helen A.; Suni, Tanja; Keith, Heather

    2007-01-01

    Micro meteorological measurements made on single towers often underestimate nighttime respiration of terrestrial ecosystems because they cannot account for vertical and horizontal advection, thereby causing systematic errors in estimates of net ecosystem carbon exchange. We show that there is a maximum in the sum of the turbulent flux and change in storage of CO 2 in the early evening, R max , that is in close agreement with concurrent and independent estimates of net carbon exchange from soil and plant chambers. We hypothesize that the peak occurs because there is a time delay between the onset of radiative cooling and the development of temperature gradients that are strong enough to initiate thermally-driven horizontal and vertical flows that remove the stored CO 2 . We propose taking advantage of this time delay to develop relationships between R max and soil temperature and moisture. The new parameterization leads to realistic values of nighttime respiration, and therefore to improved estimates of net ecosystem exchange

  8. Carbon Dioxide Impacts in the Deep-Sea: Is Maintaining a Metabolically Required CO2 Efflux Rate Challenging?

    Science.gov (United States)

    Peltzer, E. T.; Hofmann, A. F.; Brewer, P. G.

    2011-12-01

    Increasing ocean acidification from fossil fuel CO2 invasion, from temperature driven changes in respiration, and from possible leakage from sub-seabed geologic CO2 disposal has aroused concern over the impacts of elevated CO2 concentrations on marine life. Here we describe the rate problem for animals who must export CO2 at about the same rate at which O2 is consumed. We analyze the basic properties controlling CO2 export within the diffusive boundary of marine animals in a changing ocean in order to compare the challenges posed by O2 uptake under stress with the equivalent problem of CO2 expulsion. The problem is more complex than that for a non-reactive gas since, as with gas exchange of CO2 at the air-sea interface, the influence of the ensemble of reactions within the CO2 - HCO3- - CO3= acid-base system needs to be considered. These reactions appear as an enhancement factor which significantly facilitates CO2 efflux compared to O2 intake at equal temperature, pressure and flow rate under typical oceanic concentrations. Possibly as an adaptation to this chemical advantage marine animals typically can respond to external CO2 stress simply by metabolic adjustment. This is energetically more favorable than having to resort to mechanically increasing flow over their surface to thin the boundary layer as is required to alleviate O2 stress. Regionally as with O2 the combination of T, P, and pH/pCO2 creates a zone of maximum CO2 stress at around 1000 m depth. But the net result is that the combination of an increase in T combined with declining O2 poses a greater respiratory challenge to marine life than does increasing CO2. The relationships developed here allow a more accurate prediction of the impacts on marine life from the combined effects of changing T, O2, and CO2 than can be estimated from single variable studies.

  9. Mangrove production and carbon sinks: A revision of global budget estimates

    Science.gov (United States)

    Bouillon, S.; Borges, A.V.; Castaneda-Moya, E.; Diele, K.; Dittmar, T.; Duke, N.C.; Kristensen, E.; Lee, S.-Y.; Marchand, C.; Middelburg, J.J.; Rivera-Monroy, V. H.; Smith, T. J.; Twilley, R.R.

    2008-01-01

    Mangrove forests are highly productive but globally threatened coastal ecosystems, whose role in the carbon budget of the coastal zone has long been debated. Here we provide a comprehensive synthesis of the available data on carbon fluxes in mangrove ecosystems. A reassessment of global mangrove primary production from the literature results in a conservative estimate of ???-218 ?? 72 Tg C a-1. When using the best available estimates of various carbon sinks (organic carbon export, sediment burial, and mineralization), it appears that >50% of the carbon fixed by mangrove vegetation is unaccounted for. This unaccounted carbon sink is conservatively estimated at ??? 112 ?? 85 Tg C a-1, equivalent in magnitude to ??? 30-40% of the global riverine organic carbon input to the coastal zone. Our analysis suggests that mineralization is severely underestimated, and that the majority of carbon export from mangroves to adjacent waters occurs as dissolved inorganic carbon (DIC). CO2 efflux from sediments and creek waters and tidal export of DIC appear to be the major sinks. These processes are quantitatively comparable in magnitude to the unaccounted carbon sink in current budgets, but are not yet adequately constrained with the limited published data available so far. Copyright 2008 by the American Geophysical Union.

  10. A tree biomass and carbon estimation system

    Science.gov (United States)

    Emily B. Schultz; Thomas G. Matney; Donald L. Grebner

    2013-01-01

    Appropriate forest management decisions for the developing woody biofuel and carbon credit markets require inventory and growth-and-yield systems reporting component tree dry weight biomass estimates. We have developed an integrated growth-and-yield and biomass/carbon calculator. The objective was to provide Mississippi’s State inventory system with bioenergy economic...

  11. Differences between carbon budget estimates unravelled

    NARCIS (Netherlands)

    Rogelj, Joeri; Schaeffer, Michiel; Friedlingstein, Pierre; Gillett, Nathan P.; Vuuren, Van Detlef P.; Riahi, Keywan; Allen, Myles; Knutti, Reto

    2016-01-01

    Several methods exist to estimate the cumulative carbon emissions that would keep global warming to below a given temperature limit. Here we review estimates reported by the IPCC and the recent literature, and discuss the reasons underlying their differences. The most scientifically robust

  12. Differences between carbon budget estimates unravelled

    NARCIS (Netherlands)

    Rogelj, Joeri; Schaeffer, Michiel; Friedlingstein, Pierre; Gillett, Nathan P.; Van Vuuren, Detlef P.|info:eu-repo/dai/nl/11522016X; Riahi, Keywan; Allen, Myles; Knutti, Reto

    2016-01-01

    Several methods exist to estimate the cumulative carbon emissions that would keep global warming to below a given temperature limit. Here we review estimates reported by the IPCC and the recent literature, and discuss the reasons underlying their differences. The most scientifically robust

  13. In-pot evaluation of different composted and pelletized organic fertilizers on soil carbon dioxide efflux and basal respiration

    Science.gov (United States)

    Opsi, Francesca; Cavallo, Eugenio; Cocco, Stefania; Corti, Giuseppe

    2013-04-01

    Climate change is one of the most important environmental problems and it is closely related to concentration changes of greenhouse gases (GHG) in the atmosphere, mainly due to anthropogenic activities. As a consequence, measures have been taken to reduce GHG emissions, some of which are associated with agriculture, as well as to the enhancement of soil carbon storage. Modern intensive farming activities have also raised problems related to the safe disposal of large volume of animal waste, such as pig slurry, where the excessive land spreading can lead to water pollution and GHG evolution to the atmosphere. Composting is a great environmentally sustainable option for recycling agricultural by-products, and pelletisation is a promising technology to reduce the large volume of mature composted material in pelleted fertilizers, more suitable for long-distance transport. This study consisted of a pot-incubation experience carried out in a greenhouse of the National Research Council of Italy, under controlled conditions. The aim of the research was to investigate the effect of a composted swine solid fraction (CS, 13% w/w) and swine solid fraction blended with sawdust and composted (CSS, 9% w/w), both also as a result of pelletisation process (CSP, 12% w/w and CSSP, 8% w/w, respectively), on soil organic matter mineralization and basal respiration. Results were obtained by monitoring CO2 efflux, basal respiration and microbial biomass C on amended soil, freshly collected in a vineyard planted on a Typic Ustorthent, fine-loamy, mixed, calcareous, mesic. Samples, adjusted and maintained to about 50-60% of water holding capacity, were conditioned at 25±3 °C for 31 days of incubation. The CO2 fluxes showed a high production at the initial stage of incubation, where differences among treatments were well-rendered. CSSP produced the highest values, while CSS showed values as lower as about 45%. Intermediate values, and similar to those found in the soil sample used as

  14. How to estimate carbon sequestration on small forest tracts estimate carbon sequestration on small forest tracts

    Science.gov (United States)

    Coeli M. Hoover; Richard A. Birdsey; Linda S. Heath; Susan L. Stout

    2000-01-01

    International climate change agreements may allow carbon stored as a result of afforestation and reforestation to be used to offset CO2 emissions. Monitoring the carbon sequestered or released through forest management activities thus becomes important. Estimating forest carbon storage is feasible even for nonindustrial private forestland (NIPF)...

  15. Carbon dioxide efflux from soil with poultry litter applications in conventional and conservation tillage systems in northern Alabama.

    Science.gov (United States)

    Roberson, T; Reddy, K C; Reddy, S S; Nyakatawa, E Z; Raper, R L; Reeves, D W; Lemunyon, J

    2008-01-01

    Increased CO2 release from soils resulting from agricultural practices such as tillage has generated concerns about contributions to global warming. Maintaining current levels of soil C and/or sequestering additional C in soils are important mechanisms to reduce CO2 in the atmosphere through production agriculture. We conducted a study in northern Alabama from 2003 to 2006 to measure CO2 efflux and C storage in long-term tilled and non-tilled cotton (Gossypium hirsutum L.) plots receiving poultry litter or ammonium nitrate (AN). Treatments were established in 1996 on a Decatur silt loam (clayey, kaolinitic thermic, Typic Paleudults) and consisted of conventional-tillage (CT), mulch-tillage (MT), and no-tillage (NT) systems with winter rye [Secale cereale (L.)] cover cropping and AN and poultry litter (PL) as nitrogen sources. Cotton was planted in 2003, 2004, and 2006. Corn was planted in 2005 as a rotation crop using a no-till planter in all plots, and no fertilizer was applied. Poultry litter application resulted in higher CO2 emission from soil compared with AN application regardless of tillage system. In 2003 and 2006, CT (4.39 and 3.40 micromol m(-2) s(-1), respectively) and MT (4.17 and 3.39 micromol m(-2) s(-1), respectively) with PL at 100 kg N ha(-1) (100 PLN) recorded significantly higher CO2 efflux compared with NT with 100 PLN (2.84 and 2.47 micromol m(-2) s(-1), respectively). Total soil C at 0- to 15-cm depth was not affected by tillage but significantly increased with PL application and winter rye cover cropping. In general, cotton produced with NT conservation tillage in conjunction with PL and winter rye cover cropping reduced CO2 emissions and sequestered more soil C compared with control treatments.

  16. Carbon footprint estimation of municipal water cycle

    Science.gov (United States)

    Bakhshi, Ali A.

    2009-11-01

    This research investigates the embodied energy associated with water use. A geographic information system (GIS) was tested using data from Loudoun County, Virginia. The objective of this study is to estimate the embodied energy and carbon emission levels associated with water service at a geographical location and to improve for sustainability planning. Factors that affect the carbon footprint were investigated and the use of a GIS based model as a sustainability planning framework was evaluated. The carbon footprint metric is a useful tool for prediction and measurement of a system's sustainable performance over its expected life cycle. Two metrics were calculated: tons of carbon dioxide per year to represent the contribution to global warming and watt-hrs per gallon to show the embodied energy associated with water consumption. The water delivery to the building, removal of wastewater from the building and associated treatment of water and wastewater create a sizable carbon footprint; often the energy attributed to this water service is the greatest end use of electrical energy. The embodied energy in water depends on topographical characteristics of the area's local water supply, the efficiency of the treatment systems, and the efficiency of the pumping stations. The questions answered by this research are: What is the impact of demand side sustainable water practices on the embodied energy as represented by a comprehensive carbon footprint? What are the major energy consuming elements attributed to the system? What is a viable and visually identifiable tool to estimate the carbon footprint attributed to those Greenhouse Gas (GHG) producing elements? What is the embodied energy and emission associated with water use delivered to a building? Benefits to be derived from a standardized GIS applied carbon footprint estimation approach include: (1) Improved environmental and economic information for the developers, water and wastewater processing and municipal

  17. Gluconeogenesis from labeled carbon: estimating isotope dilution

    International Nuclear Information System (INIS)

    Kelleher, J.K.

    1986-01-01

    To estimate the rate of gluconeogenesis from steady-state incorporation of labeled 3-carbon precursors into glucose, isotope dilution must be considered so that the rate of labeling of glucose can be quantitatively converted to the rate of gluconeogenesis. An expression for the value of this isotope dilution can be derived using mathematical techniques and a model of the tricarboxylic acid (TCA) cycle. The present investigation employs a more complex model than that used in previous studies. This model includes the following pathways that may affect the correction for isotope dilution: 1) flux of 3-carbon precursor to the oxaloacetate pool via acetyl-CoA and the TCA cycle; 2) flux of 4- or 5-carbon compounds into the TCA cycle; 3) reversible flux between oxaloacetate (OAA) and pyruvate and between OAA and fumarate; 4) incomplete equilibrium between OAA pools; and 5) isotope dilution of 3-carbon tracers between the experimentally measured pool and the precursor for the TCA-cycle OAA pool. Experimental tests are outlined which investigators can use to determine whether these pathways are significant in a specific steady-state system. The study indicated that flux through these five pathways can significantly affect the correction for isotope dilution. To correct for the effects of these pathways an alternative method for calculating isotope dilution is proposed using citrate to relate the specific activities of acetyl-CoA and OAA

  18. Warming-related increases in soil CO2 efflux are explained by increased below-ground carbon flux

    Science.gov (United States)

    Christian P. Giardina; Creighton M. Litton; Susan E. Crow; Gregory P Asner

    2014-01-01

    The universally observed exponential increase in soil-surface CO2 effux (‘soil respiration’; FS) with increasing temperature has led to speculation that global warming will accelerate soil organic carbon (SOC) decomposition, reduce SOC storage, and drive a positive feedback to future warming. However, interpreting temperature–FS relationships,...

  19. [Effect of bamboo leaf biochar addition on soil CO2 efflux and labile organic carbon pool in a Chinese chestnut plantation].

    Science.gov (United States)

    Wang, Zhan-Lei; Li, Yong-Fu; Jiang, Pei-Kun; Zhou, Guo-Mo; Liu, Juan

    2014-11-01

    Effect of biochar addition on soil CO2 efflux in a typical Chinese chestnut (Castanea mollissima) plantation in Lin'an, Zhejiang Province, China was investigated from July 2012 to July 2013 by the static closed chamber-GC technique. Soil temperature, soil moisture, WSOC and MBC concentrations were determined as well. Results showed that soil CO2 efflux exhibited a strong sea- sonal pattern. Compared with the control (without biochar application), the biochar treatment increased the soil CO2 efflux only in the first month since application, and then the effect diminished thereafter. There were no significant differences in the annual cumulative value of soil CO2 efflux between the biochar and control treatments. The annual mean value in soil MBC concentration (362 mg · kg(-1)) in the biochar treatment was higher than that (322 mg · kg(-1)) in the control. However, no significant difference in the soil WSOC concentration was found between the biochar and control treatments. Strong exponential relationships between soil temperature and soil CO2 efflux were observed regardless of the treatment and soil layer. The apparent temperature sensitivity (Q10) of soil CO2 efflux in the biochar treatment was higher than that in the control. Soil CO2 efflux was related to soil WSOC concentration but not with soil MBC or moisture content. To conclude, the application of bamboo leaf biochar did not affect the annual cumulative CO2 emission in the Chinese chestnut plantation but increased the Q10, and the CO2 efflux was predominantly controlled by the soil temperature and soil WSOC level.

  20. Vertical profile of branch CO2 efflux in a Norway spruce tree: a case study

    Science.gov (United States)

    Acosta, M.; Pavelka, M.

    2012-04-01

    Despite woody-tissue CO2 effluxes having been recognized as an important component of forest carbon budget due to the fraction of assimilates used and the dramatic increase in woody with stand development, there is limited research to determine the CO2 efflux vertical variability of woody-tissue components. For a better understanding and quantification of branch woody-tissue CO2 efflux in forest ecosystems, it is necessary to identify the environmental factors influencing it and the role of the branch distribution within the canopy. The proper assessment of this forest component will improve the knowledge of the ratio between ecosystem respiration and gross primary production at forest ecosystem. In order to achieve this goal, branch CO2 efflux of Norway spruce tree was measured in ten branches at five different whorls during the growing season 2004 (from June till October) in campaigns of 3-4 times per month at the Beskydy Mts., the Czech Republic, using a portable infrared gas analyzer operating as a closed system. Branch woody tissue temperature was measured continuously in ten minutes intervals for each sample position during the whole experiment period. On the basis of relation between CO2 efflux rate and woody tissue temperature a value of Q10 and normalized CO2 efflux rate (E10 - CO2 efflux rate at 10° C) were calculated for each sampled position. Estimated Q10 values ranged from 2.12 to 2.89 and E10 ranged from 0.41 to 1.19 ?molCO2m-2 s-1. Differences in branch CO2 efflux were found between orientations; East side branches presented higher efflux rate than west side branches. The highest branch CO2 efflux rate values were measured in August and the lowest in October, which were connected with woody tissue temperature and ontogenetic processes during these periods. Branch CO2 efflux was significantly and positively correlated with branch position within canopy and woody tissue temperature. Branches from the upper whorls showed higher respiration activity

  1. Effect of measurement time of the day on the relationship between temperature and soil CO2 efflux

    Directory of Open Access Journals (Sweden)

    Eva Dařenová

    2011-01-01

    Full Text Available In this study we investigated effect of the time of the day when manual measurements of soil CO2 efflux are performed on estimates of seasonal sums of released carbon from the soil. We subsampled continuous measurement of soil CO2 efflux into six sets of data in accordance to the time of the day when the measurements were taken – 0 h, 4 h, 8 h, 12 h, 16 h and 20 h. To estimate seasonal carbon flux from the soil we used continuously measured soil temperature and parameters R10 (soil CO2 efflux normalized for temperature of 10 °C and Q10 (the proportional change in CO2 efflux caused by 10 °C increase in temperature calculated from continuous measurements and from measurements taken at individual hours. Values of Q10 calculated from 12 h and 16 h data were lower than Q10 calculated from continuous measurements. On the contrary, Q10 at 0 h, 4 h, 8 h and 20 h were higher. Seasonal carbon flux from the soil based on 0 h, 4 h and 8 h measurements was overestimated compare to the flux calculated from continuous measurements. On the contrary, measurements at 12 h, 16 h and 20 h measurements underestimated the carbon flux. The under- or overestimation was significant for 0 h, 4 h, 8 h and 20 h data sub-sets.

  2. Environmental controls of daytime leaf carbon exchange: Implications for estimates of ecosystem fluxes in a deciduous forest

    Science.gov (United States)

    Heskel, M.; Tang, J.

    2017-12-01

    Leaf-level photosynthesis and respiration are sensitive to short- and long-term changed in temperature, and how these processes respond to phenological and seasonal transitions and daily temperature variation dictate how carbon is first assimilated and released in terrestrial ecosystems. We examined the short-term temperature response of daytime leaf carbon exchange at Harvard Forest across growing season, with the specific objective to quantify the light inhibition of dark respiration and photorespiration in leaves and use this to better inform daytime carbon assimilation and efflux estimates at the canopy scale. Dark and light respiration increased with measurement temperature and varied seasonally in a proportional manner, with the level of inhibition remaining relatively constant through the growing season. Higher rates of mitochondrial respiration and photorespiration at warmer temperatures drove a lower carbon use efficiency. Using temperature, light, and canopy leaf area index values to drive models, we estimate partitioned ecosystem fluxes and re-calculate gross primary production under multiple scenarios that include and exclude the impact of light inhibition, thermal acclimation, and seasonal variation in physiology. Quantifying the contribution of these `small fluxes' to ecosystem carbon exchange in forests provides a nuanced approach for integrating physiology into regional model estimates derived from eddy covariance and remote-sensing methods.

  3. Estimation of fractional contribution of root respiration to a forest-floor CO2 flux using carbon isotopes

    International Nuclear Information System (INIS)

    Hachiya, Masashi; Moriizumi, Jun; Yamazawa, Hiromi

    2010-01-01

    Efflux of soil respired carbon dioxide(CO 2 ) is very important component for the global carbon cycle and dynamics of 14 C in environment, and to predict the global climate changes caused by increasing CO 2 concentrations in the atmosphere. There are two components that generate CO 2 in soil, soil organic matter decomposition and root respiration. Although the former is relatively well understood, the root-derived CO 2 efflux has not been evaluated sufficiently. The objective of our research is to estimate depth profile of the root respiration rate. Thus we developed a box model which calculates the depth profile. In this paper, we discussed about (1) the adequacy of calculated result by comparing it to the to observed soil respired CO 2 flux with trenching method and (2) sensitivity of the box model to uncertainty in the input data. The result showed that the depth profile of root respiration rate decreased with soil depth. This is attributed to the distribution of fine roots which dominate root respiration. The model results reasonable agreed with the measurement results and characteristics of root respiration. The output of the model was robust to the variation of the input data. (author)

  4. Methodology for estimating soil carbon for the forest carbon budget model of the United States, 2001

    Science.gov (United States)

    L. S. Heath; R. A. Birdsey; D. W. Williams

    2002-01-01

    The largest carbon (C) pool in United States forests is the soil C pool. We present methodology and soil C pool estimates used in the FORCARB model, which estimates and projects forest carbon budgets for the United States. The methodology balances knowledge, uncertainties, and ease of use. The estimates are calculated using the USDA Natural Resources Conservation...

  5. Carbon footprint: current methods of estimation.

    Science.gov (United States)

    Pandey, Divya; Agrawal, Madhoolika; Pandey, Jai Shanker

    2011-07-01

    Increasing greenhouse gaseous concentration in the atmosphere is perturbing the environment to cause grievous global warming and associated consequences. Following the rule that only measurable is manageable, mensuration of greenhouse gas intensiveness of different products, bodies, and processes is going on worldwide, expressed as their carbon footprints. The methodologies for carbon footprint calculations are still evolving and it is emerging as an important tool for greenhouse gas management. The concept of carbon footprinting has permeated and is being commercialized in all the areas of life and economy, but there is little coherence in definitions and calculations of carbon footprints among the studies. There are disagreements in the selection of gases, and the order of emissions to be covered in footprint calculations. Standards of greenhouse gas accounting are the common resources used in footprint calculations, although there is no mandatory provision of footprint verification. Carbon footprinting is intended to be a tool to guide the relevant emission cuts and verifications, its standardization at international level are therefore necessary. Present review describes the prevailing carbon footprinting methods and raises the related issues.

  6. Comparison of methods for estimating carbon in harvested wood products

    International Nuclear Information System (INIS)

    Claudia Dias, Ana; Louro, Margarida; Arroja, Luis; Capela, Isabel

    2009-01-01

    There is a great diversity of methods for estimating carbon storage in harvested wood products (HWP) and, therefore, it is extremely important to agree internationally on the methods to be used in national greenhouse gas inventories. This study compares three methods for estimating carbon accumulation in HWP: the method suggested by Winjum et al. (Winjum method), the tier 2 method proposed by the IPCC Good Practice Guidance for Land Use, Land-Use Change and Forestry (GPG LULUCF) (GPG tier 2 method) and a method consistent with GPG LULUCF tier 3 methods (GPG tier 3 method). Carbon accumulation in HWP was estimated for Portugal under three accounting approaches: stock-change, production and atmospheric-flow. The uncertainty in the estimates was also evaluated using Monte Carlo simulation. The estimates of carbon accumulation in HWP obtained with the Winjum method differed substantially from the estimates obtained with the other methods, because this method tends to overestimate carbon accumulation with the stock-change and the production approaches and tends to underestimate carbon accumulation with the atmospheric-flow approach. The estimates of carbon accumulation provided by the GPG methods were similar, but the GPG tier 3 method reported the lowest uncertainties. For the GPG methods, the atmospheric-flow approach produced the largest estimates of carbon accumulation, followed by the production approach and the stock-change approach, by this order. A sensitivity analysis showed that using the ''best'' available data on production and trade of HWP produces larger estimates of carbon accumulation than using data from the Food and Agriculture Organization. (author)

  7. Estimating forest carbon stocks in tropical dry forests of Zimbabwe ...

    African Journals Online (AJOL)

    Estimation and mapping of forest dendrometric characteristics such as carbon stocks using remote sensing techniques is fundamental for improved understanding of the role of forests in the carbon cycle and climate change. In this study, we tested whether and to what extent spectral transforms, i.e. vegetation indices ...

  8. Models for estimation of carbon sequestered by Cupressus ...

    African Journals Online (AJOL)

    This study compared models for estimating carbon sequestered aboveground in Cupressus lusitanica plantation stands at Wondo Genet College of Forestry and Natural Resources, Ethiopia. Relationships of carbon storage with tree component and stand age were also investigated. Thirty trees of three different ages (5, ...

  9. Estimation and Minimization of Embodied Carbon of Buildings: A Review

    Directory of Open Access Journals (Sweden)

    Ali Akbarnezhad

    2017-01-01

    Full Text Available Building and construction is responsible for up to 30% of annual global greenhouse gas (GHG emissions, commonly reported in carbon equivalent unit. Carbon emissions are incurred in all stages of a building’s life cycle and are generally categorised into operating carbon and embodied carbon, each making varying contributions to the life cycle carbon depending on the building’s characteristics. With recent advances in reducing the operating carbon of buildings, the available literature indicates a clear shift in attention towards investigating strategies to minimize embodied carbon. However, minimizing the embodied carbon of buildings is challenging and requires evaluating the effects of embodied carbon reduction strategies on the emissions incurred in different life cycle phases, as well as the operating carbon of the building. In this paper, the available literature on strategies for reducing the embodied carbon of buildings, as well as methods for estimating the embodied carbon of buildings, is reviewed and the strengths and weaknesses of each method are highlighted.

  10. Estimating carbon stock in secondary forests

    DEFF Research Database (Denmark)

    Breugel, Michiel van; Ransijn, Johannes; Craven, Dylan

    2011-01-01

    of trees and species for destructive biomass measurements. We assess uncertainties associated with these decisions using data from 94 secondary forest plots in central Panama and 244 harvested trees belonging to 26 locally abundant species. AGB estimates from species-specific models were used to assess...... is the use of allometric regression models to convert forest inventory data to estimates of aboveground biomass (AGB). The use of allometric models implies decisions on the selection of extant models or the development of a local model, the predictor variables included in the selected model, and the number...... relative errors of estimates from multispecies models. To reduce uncertainty in the estimation of plot AGB, including wood specific gravity (WSG) in the model was more important than the number of trees used for model fitting. However, decreasing the number of trees increased uncertainty of landscape...

  11. State-Space Estimation of Soil Organic Carbon Stock

    Science.gov (United States)

    Ogunwole, Joshua O.; Timm, Luis C.; Obidike-Ugwu, Evelyn O.; Gabriels, Donald M.

    2014-04-01

    Understanding soil spatial variability and identifying soil parameters most determinant to soil organic carbon stock is pivotal to precision in ecological modelling, prediction, estimation and management of soil within a landscape. This study investigates and describes field soil variability and its structural pattern for agricultural management decisions. The main aim was to relate variation in soil organic carbon stock to soil properties and to estimate soil organic carbon stock from the soil properties. A transect sampling of 100 points at 3 m intervals was carried out. Soils were sampled and analyzed for soil organic carbon and other selected soil properties along with determination of dry aggregate and water-stable aggregate fractions. Principal component analysis, geostatistics, and state-space analysis were conducted on the analyzed soil properties. The first three principal components explained 53.2% of the total variation; Principal Component 1 was dominated by soil exchange complex and dry sieved macroaggregates clusters. Exponential semivariogram model described the structure of soil organic carbon stock with a strong dependence indicating that soil organic carbon values were correlated up to 10.8m.Neighbouring values of soil organic carbon stock, all waterstable aggregate fractions, and dithionite and pyrophosphate iron gave reliable estimate of soil organic carbon stock by state-space.

  12. Land-use change and carbon sinks: Econometric estimation of the carbon sequestration supply function

    Energy Technology Data Exchange (ETDEWEB)

    Lubowski, Ruben N.; Plantinga, Andrew J.; Stavins, Robert N.

    2001-01-01

    Increased attention by policy makers to the threat of global climate change has brought with it considerable interest in the possibility of encouraging the expansion of forest area as a means of sequestering carbon dioxide. The marginal costs of carbon sequestration or, equivalently, the carbon sequestration supply function will determine the ultimate effects and desirability of policies aimed at enhancing carbon uptake. In particular, marginal sequestration costs are the critical statistic for identifying a cost-effective policy mix to mitigate net carbon dioxide emissions. We develop a framework for conducting an econometric analysis of land use for the forty-eight contiguous United States and employing it to estimate the carbon sequestration supply function. By estimating the opportunity costs of land on the basis of econometric evidence of landowners' actual behavior, we aim to circumvent many of the shortcomings of previous sequestration cost assessments. By conducting the first nationwide econometric estimation of sequestration costs, endogenizing prices for land-based commodities, and estimating land-use transition probabilities in a framework that explicitly considers the range of land-use alternatives, we hope to provide better estimates eventually of the true costs of large-scale carbon sequestration efforts. In this way, we seek to add to understanding of the costs and potential of this strategy for addressing the threat of global climate change.

  13. Land-use change and carbon sinks: Econometric estimation of the carbon sequestration supply function; FINAL

    International Nuclear Information System (INIS)

    Lubowski, Ruben N.; Plantinga, Andrew J.; Stavins, Robert N.

    2001-01-01

    Increased attention by policy makers to the threat of global climate change has brought with it considerable interest in the possibility of encouraging the expansion of forest area as a means of sequestering carbon dioxide. The marginal costs of carbon sequestration or, equivalently, the carbon sequestration supply function will determine the ultimate effects and desirability of policies aimed at enhancing carbon uptake. In particular, marginal sequestration conts are the critical statistic for identifying a cost-effective policy mix to mitigate net carbon dioxide emissions. We develop a framework for conducting an econometric analysis of land use for the forty-eight contiguous United States and employing it to estimate the carbon sequestration supply function. By estimating the opportunity costs of land on the basis of econometric evidence of landowners' actual behavior, we aim to circumvent many of the shortcomings of previous sequestration cost assessments. By conducting the first nationwide econometric estimation of sequestration costs, endogenizing prices for land-based commodities, and estimating land-use transition probabilities in a framework that explicitly considers the range of land-use alternatives, we hope to provide better estimates eventually of the true costs of large-scale carbon sequestration efforts. In this way, we seek to add to understanding of the costs and potential of this strategy for addressing the threat of global climate change

  14. Estimation of Carbon Sink in Surface Carbonate Rocks of Guangxi Province by Using Remote Sensing Images

    Science.gov (United States)

    Jia, B.; Zhou, G.; Wang, H.; Yue, T.; Huang, W.

    2018-04-01

    Studies of the imbalance of source sinks in the carbon cycle show that CO2 absorbed during rock weathering is part of the "miss carbon" of the global carbon cycle. The carbon sink contribution of carbonate rocks obviously plays a very important role in the absorption of atmospheric CO2. Estimation of carbon sinks in karst dynamic system of Guangxi province has great significance for further understanding of global karst carbon cycle and global climate research. This paper quotes the rock data from Tao Xiaodong's paper, which is obtained using RS and GIS techniques. At the same time, the dissolution rate model studied by Zhou Guoqing and others was used to estimate the dissolution rate of carbonate rocks in Guangxi Province. Finally, the CO2 content consumed by carbonate karstification in Guangxi Province was 1342910.447 t a-1. The results obtained are in the same order of magnitude as the CO2 content consumed by carbonate rock karstification in Guangxi Province calculated by Tao Xiaodong.

  15. 1km Global Terrestrial Carbon Flux: Estimations and Evaluations

    Science.gov (United States)

    Murakami, K.; Sasai, T.; Kato, S.; Saito, M.; Matsunaga, T.; Hiraki, K.; Maksyutov, S. S.

    2017-12-01

    Estimating global scale of the terrestrial carbon flux change with high accuracy and high resolution is important to understand global environmental changes. Furthermore the estimations of the global spatiotemporal distribution may contribute to the political and social activities such as REDD+. In order to reveal the current state of terrestrial carbon fluxes covering all over the world and a decadal scale. The satellite-based diagnostic biosphere model is suitable for achieving this purpose owing to observing on the present global land surface condition uniformly at some time interval. In this study, we estimated the global terrestrial carbon fluxes with 1km grids by using the terrestrial biosphere model (BEAMS). And we evaluated our new carbon flux estimations on various spatial scales and showed the transition of forest carbon stocks in some regions. Because BEAMS required high resolution meteorological data and satellite data as input data, we made 1km interpolated data using a kriging method. The data used in this study were JRA-55, GPCP, GOSAT L4B atmospheric CO2 data as meteorological data, and MODIS land product as land surface satellite data. Interpolating process was performed on the meteorological data because of insufficient resolution, but not on MODIS data. We evaluated our new carbon flux estimations using the flux tower measurement (FLUXNET2015 Datasets) in a point scale. We used 166 sites data for evaluating our model results. These flux sites are classified following vegetation type (DBF, EBF, ENF, mixed forests, grass lands, croplands, shrub lands, Savannas, wetlands). In global scale, the BEAMS estimations was underestimated compared to the flux measurements in the case of carbon uptake and release. The monthly variations of NEP showed relatively high correlations in DBF and mixed forests, but the correlation coefficients of EBF, ENF, and grass lands were less than 0.5. In the meteorological factors, air temperature and solar radiation showed

  16. Efflux-mediated antimicrobial resistance.

    Science.gov (United States)

    Poole, Keith

    2005-07-01

    Antibiotic resistance continues to plague antimicrobial chemotherapy of infectious disease. And while true biocide resistance is as yet unrealized, in vitro and in vivo episodes of reduced biocide susceptibility are common and the history of antibiotic resistance should not be ignored in the development and use of biocidal agents. Efflux mechanisms of resistance, both drug specific and multidrug, are important determinants of intrinsic and/or acquired resistance to these antimicrobials, with some accommodating both antibiotics and biocides. This latter raises the spectre (as yet generally unrealized) of biocide selection of multiple antibiotic-resistant organisms. Multidrug efflux mechanisms are broadly conserved in bacteria, are almost invariably chromosome-encoded and their expression in many instances results from mutations in regulatory genes. In contrast, drug-specific efflux mechanisms are generally encoded by plasmids and/or other mobile genetic elements (transposons, integrons) that carry additional resistance genes, and so their ready acquisition is compounded by their association with multidrug resistance. While there is some support for the latter efflux systems arising from efflux determinants of self-protection in antibiotic-producing Streptomyces spp. and, thus, intended as drug exporters, increasingly, chromosomal multidrug efflux determinants, at least in Gram-negative bacteria, appear not to be intended as drug exporters but as exporters with, perhaps, a variety of other roles in bacterial cells. Still, given the clinical significance of multidrug (and drug-specific) exporters, efflux must be considered in formulating strategies/approaches to treating drug-resistant infections, both in the development of new agents, for example, less impacted by efflux and in targeting efflux directly with efflux inhibitors.

  17. Radiation dose estimates for carbon-11-labelled PET tracers

    International Nuclear Information System (INIS)

    Aart, Jasper van der; Hallett, William A.; Rabiner, Eugenii A.; Passchier, Jan; Comley, Robert A.

    2012-01-01

    Introduction: Carbon-11-labelled positron emission tomography (PET) tracers commonly used in biomedical research expose subjects to ionising radiation. Dosimetry is the measurement of radiation dose, but also commonly refers to the estimation of health risk associated with ionising radiation. This review describes radiation dosimetry of carbon-11-labelled molecules in the context of current PET research and the most widely used regulatory guidelines. Methods: A MEDLINE literature search returned 42 articles; 32 of these were based on human PET data dealing with radiation dosimetry of carbon-11 molecules. Radiation burden expressed as effective dose and maximum absorbed organ dose was compared between tracers. Results: All but one of the carbon-11-labelled PET tracers have an effective dose under 9 μSv/MBq, with a mean of 5.9 μSv/MBq. Data show that serial PET scans in a single subject are feasible for the majority of radiotracers. Conclusion: Although differing in approach, the two most widely used regulatory frameworks (those in the USA and the EU) do not differ substantially with regard to the maximum allowable injected activity per PET study. The predictive validity of animal dosimetry models is critically discussed in relation to human dosimetry. Finally, empirical PET data are related to human dose estimates based on homogenous distribution, generic models and maximum cumulated activities. Despite the contribution of these models to general risk estimation, human dosimetry studies are recommended where continued use of a new PET tracer is foreseen.

  18. Tropical Africa: Land use, biomass, and carbon estimates for 1980

    Energy Technology Data Exchange (ETDEWEB)

    Brown, S. [Environmental Protection Agency, Corvallis, OR (United States). Western Ecology Division; Gaston, G. [Environmental Protection Agency, Corvallis, OR (United States). National Research Council; Daniels, R.C. [ed.] [Oak Ridge National Lab., TN (United States)

    1996-06-01

    This document describes the contents of a digital database containing maximum potential aboveground biomass, land use, and estimated biomass and carbon data for 1980 and describes a methodology that may be used to extend this data set to 1990 and beyond based on population and land cover data. The biomass data and carbon estimates are for woody vegetation in Tropical Africa. These data were collected to reduce the uncertainty associated with the possible magnitude of historical releases of carbon from land use change. Tropical Africa is defined here as encompassing 22.7 x 10{sup 6} km{sup 2} of the earth`s land surface and includes those countries that for the most part are located in Tropical Africa. Countries bordering the Mediterranean Sea and in southern Africa (i.e., Egypt, Libya, Tunisia, Algeria, Morocco, South Africa, Lesotho, Swaziland, and Western Sahara) have maximum potential biomass and land cover information but do not have biomass or carbon estimate. The database was developed using the GRID module in the ARC/INFO{sup TM} geographic information system. Source data were obtained from the Food and Agriculture Organization (FAO), the U.S. National Geophysical Data Center, and a limited number of biomass-carbon density case studies. These data were used to derive the maximum potential and actual (ca. 1980) aboveground biomass-carbon values at regional and country levels. The land-use data provided were derived from a vegetation map originally produced for the FAO by the International Institute of Vegetation Mapping, Toulouse, France.

  19. Unravelling ecosystem functions at the Amazonia-Cerrado transition: II. Carbon stocks and CO2 soil efflux in cerradão forest undergoing ecological succession

    Science.gov (United States)

    Peixoto, Karine S.; Marimon-Junior, Ben Hur; Marimon, Beatriz S.; Elias, Fernando; de Farias, Josenilton; Freitag, Renata; Mews, Henrique A.; das Neves, Eder C.; Prestes, Nayane Cristina C. S.; Malhi, Yadvinder

    2017-07-01

    The transition region between two major South American biomes, the Amazon forest and the Cerrado (Brazilian savanna), has been substantially converted into human-modified ecosystems. Nevertheless, the recovery dynamics of ecosystem functions in this important zone of (ecological) tension (ZOT) remain poorly understood. In this study, we compared two areas of cerradão (a forest-woodland of the Brazilian savanna; Portuguese augmentative of cerrado), one in secondary succession (SC) and one adjacent and well preserved (PC), to test whether the ecosystem functions lost after conversion to pasture were restored after 22 years of regeneration. We tested the hypothesis that the increase in annual aboveground biomass in the SC would be greater than that in the PC because of anticipated successional gains. We also investigated soil CO2 efflux, litter layer content, and fine root biomass in both the SC and PC. In terms of biomass recovery our hypothesis was not supported: the biomass did not increase in the successional area over the study period, which suggested limited capacity for recovery in this key ecosystem compartment. By contrast, the structure and function of the litter layer and root mat were largely reconstituted in the secondary vegetation. Overall, we provide evidence that 22 years of secondary succession were not sufficient for these short and open forests (e.g., cerradão) in the ZOT to recover ecosystem functions to the levels observed in preserved vegetation of identical physiognomy.

  20. Overestimation of closed-chamber soil CO2 effluxes at low atmospheric turbulence

    DEFF Research Database (Denmark)

    Brændholt, Andreas; Larsen, Klaus Steenberg; Ibrom, Andreas

    2017-01-01

    Soil respiration (R-s) is an important component of ecosystem carbon balance, and accurate quantification of the diurnal and seasonal variation of R-s is crucial for a correct interpretation of the response of R-s to biotic and abiotic factors, as well as for estimating annual soil CO2 efflux rates...... be eliminated if proper mixing of air is ensured, and indeed the use of fans removed the overestimation of R-s rates during low u(*). Artificial turbulent air mixing may thus provide a method to overcome the problems of using closed-chamber gas-exchange measurement techniques during naturally occurring low...

  1. Vertical variations in wood CO2 efflux for live emergent trees in a Bornean tropical rainforest.

    Science.gov (United States)

    Katayama, Ayumi; Kume, Tomonori; Komatsu, Hikaru; Ohashi, Mizue; Matsumoto, Kazuho; Ichihashi, Ryuji; Kumagai, Tomo'omi; Otsuki, Kyoichi

    2014-05-01

    Difficult access to 40-m-tall emergent trees in tropical rainforests has resulted in a lack of data related to vertical variations in wood CO2 efflux, even though significant variations in wood CO2 efflux are an important source of errors when estimating whole-tree total wood CO2 efflux. This study aimed to clarify vertical variations in wood CO2 efflux for emergent trees and to document the impact of the variations on the whole-tree estimates of stem and branch CO2 efflux. First, we measured wood CO2 efflux and factors related to tree morphology and environment for seven live emergent trees of two dipterocarp species at four to seven heights of up to ∼ 40 m for each tree using ladders and a crane. No systematic tendencies in vertical variations were observed for all the trees. Wood CO2 efflux was not affected by stem and air temperature, stem diameter, stem height or stem growth. The ratios of wood CO2 efflux at the treetop to that at breast height were larger in emergent trees with relatively smaller diameters at breast height. Second, we compared whole-tree stem CO2 efflux estimates using vertical measurements with those based on solely breast height measurements. We found similar whole-tree stem CO2 efflux estimates regardless of the patterns of vertical variations in CO2 efflux because the surface area in the canopy, where wood CO2 efflux often differed from that at breast height, was very small compared with that at low stem heights, resulting in little effect of the vertical variations on the estimate. Additionally, whole-tree branch CO2 efflux estimates using measured wood CO2 efflux in the canopy were considerably different from those measured using only breast height measurements. Uncertainties in wood CO2 efflux in the canopy did not cause any bias in stem CO2 efflux scaling, but affected branch CO2 efflux. © The Author 2014. Published by Oxford University Press. All rights reserved.

  2. Variability in soil CO2 production and surface CO2 efflux across riparian-hillslope transitions

    Science.gov (United States)

    Vincent Jerald. Pacific

    2007-01-01

    The spatial and temporal controls on soil CO2 production and surface CO2 efflux have been identified as an outstanding gap in our understanding of carbon cycling. I investigated both the spatial and temporal variability of soil CO2 concentrations and surface CO2 efflux across eight topographically distinct riparian-hillslope transitions in the ~300 ha subalpine upper-...

  3. [Regional and global estimates of carbon stocks and carbon sequestration capacity in forest ecosystems: A review].

    Science.gov (United States)

    Liu, Wei-wei; Wang, Xiao-ke; Lu, Fei; Ouyang, Zhi-yun

    2015-09-01

    As a dominant part of terrestrial ecosystems, forest ecosystem plays an important role in absorbing atmospheric CO2 and global climate change mitigation. From the aspects of zonal climate and geographical distribution, the present carbon stocks and carbon sequestration capacity of forest ecosystem were comprehensively examined based on the review of the latest literatures. The influences of land use change on forest carbon sequestration were analyzed, and factors that leading to the uncertainty of carbon sequestration assessment in forest ecosystem were also discussed. It was estimated that the current forest carbon stock was in the range of 652 to 927 Pg C and the carbon sequestration capacity was approximately 4.02 Pg C · a(-1). In terms of zonal climate, the carbon stock and carbon sequestration capacity of tropical forest were the maximum, about 471 Pg C and 1.02-1.3 Pg C · a(-1) respectively; then the carbon stock of boreal forest was about 272 Pg C, while its carbon sequestration capacity was the minimum, approximately 0.5 Pg C · a(-1); for temperate forest, the carbon stock was minimal, around 113 to 159 Pg C and its carbon sequestration capacity was 0.8 Pg C · a(-1). From the aspect of geographical distribution, the carbon stock of forest ecosystem in South America was the largest (187.7-290 Pg C), then followed by European (162.6 Pg C), North America (106.7 Pg C), Africa (98.2 Pg C) and Asia (74.5 Pg C), and Oceania (21.7 Pg C). In addition, carbon sequestration capacity of regional forest ecosystem was summed up as listed below: Tropical South America forest was the maximum (1276 Tg C · a(-1)), then were Tropical Africa (753 Tg C · a(-1)), North America (248 Tg C · a(-1)) and European (239 Tg C · a(-1)), and East Asia (98.8-136.5 Tg C · a(-1)) was minimum. To further reduce the uncertainty in the estimations of the carbon stock and carbon sequestration capacity of forest ecosystem, comprehensive application of long-term observation, inventories

  4. Soil Co2 Efflux and Soil Carbon Content as Influenced by Thinning in Loblolly Pine Plantations on the Piedmont of Virginia

    OpenAIRE

    Selig, Marcus Franklin

    2003-01-01

    The thinning of loblolly pine plantations has a great potential to influence the fluxes and storage of carbon within managed stands. This study looked at the effects of thinning on aboveground carbon and mineral soil carbon storage, 14-years after the thinning of an 8-year-old loblolly pine plantation on the piedmont of Virginia. The study also examined soil respiration for one year following the second thinning of the same stand at age twenty-two. The study was conducted using three repli...

  5. Estimation of organic carbon loss potential in north of Iran

    Science.gov (United States)

    Shahriari, A.; Khormali, F.; Kehl, M.; Welp, G.; Scholz, Ch.

    2009-04-01

    The development of sustainable agricultural systems requires techniques that accurately monitor changes in the amount, nature and breakdown rate of soil organic matter and can compare the rate of breakdown of different plant or animal residues under different management systems. In this research, the study area includes the southern alluvial and piedmont plains of Gorgan River extended from east to west direction in Golestan province, Iran. Samples from 10 soil series and were collected from cultivation depth (0-30 cm). Permanganate-oxidizable carbon (POC) an index of soil labile carbon, was used to show soil potential loss of organic carbon. In this index shows the maximum loss of OC in a given soil. Maximum loss of OC for each soil series was estimated through POC and bulk density (BD). The potential loss of OC were estimated between 1253263 and 2410813 g/ha Carbon. Stable organic constituents in the soil include humic substances and other organic macromolecules that are intrinsically resistant against microbial attack, or that are physically protected by adsorption on mineral surfaces or entrapment within clay and mineral aggregates. However, the (Clay + Silt)/OC ratio had a negative significant (p < 0.001) correlation with POC content, confirming the preserving effect of fine particle.

  6. Improved stove programs need robust methods to estimate carbon offsets

    OpenAIRE

    Johnson, Michael; Edwards, Rufus; Masera, Omar

    2010-01-01

    Current standard methods result in significant discrepancies in carbon offset accounting compared to approaches based on representative community based subsamples, which provide more realistic assessments at reasonable cost. Perhaps more critically, neither of the currently approved methods incorporates uncertainties inherent in estimates of emission factors or non-renewable fuel usage (fNRB). Since emission factors and fNRB contribute 25% and 47%, respectively, to the overall uncertainty in ...

  7. [Efflux systems in Serratia marcescens].

    Science.gov (United States)

    Mardanova, A M; Bogomol'naia, L M; Romanova, Iu D; Sharipova, M R

    2014-01-01

    A widespread bacterium Serratia marcescens (family Enterobacteriaceae) is an opportunistic and exhibits multiple drug resistance. Active removal of antibiotics and other antimicrobials from pathogen and exhibits multiple drug resistance. Active removal of antibiotics and other antimicrobials from the cells by efflux systems is one of the mechanisms responsible for microbial resistance to these compounds. Among enterobacteria, efflux systems of Escherichia coli and Salmonella enterica var. Typhimurium have been studied most extensively. Few efflux systems that belong to different families have been reported for S. marcescens. In this review, we analyzed available literature about S. marcescens efflux systems and carried out the comparative analysis of the genes encoding the RND type systems in different Serratia species and in other enterobacteria. Bioinformatical analysis of the S. marcescens genome allowed us to identify the previously unknown efflux systems based on their homology with the relevant E. coli genes. Identification of additional efflux systems in S. marcescens genome will promote our understanding of physiology of these bacteria, will detect new molecular mechanisms of resistance and will reveal their resistance potential.

  8. Influence of repeated canopy scorching on soil CO2 efflux

    Science.gov (United States)

    DP Aubrey; B Martazavi; Joseph O' Brien; JD McGee; JJ Hendricks; KA Kuehn; RJ Mitchell

    2012-01-01

    Forest ecosystems experience various disturbances that can affect belowground carbon cycling to different degrees. Here, we investigate if successive annual foliar scorching events will result in a large and rapid decline in soil CO2 efflux, similar to that observed in girdling studies. Using the fire-adapted longleaf pine (Pinus...

  9. Accounting for black carbon lowers estimates of blue carbon storage services.

    Science.gov (United States)

    Chew, Swee Theng; Gallagher, John B

    2018-02-07

    The canopies and roots of seagrass, mangrove, and saltmarsh protect a legacy of buried sedimentary organic carbon from resuspension and remineralisation. This legacy's value, in terms of mitigating anthropogenic emissions of CO 2 , is based on total organic carbon (TOC) inventories to a depth likely to be disturbed. However, failure to subtract allochthonous recalcitrant carbon overvalues the storage service. Simply put, burial of oxidation-resistant organics formed outside of the ecosystem provides no additional protection from remineralisation. Here, we assess whether black carbon (BC), an allochthonous and recalcitrant form of organic carbon, is contributing to a significant overestimation of blue carbon stocks. To test this supposition, BC and TOC contents were measured in different types of seagrass and mangrove sediment cores across tropical and temperate regimes, with different histories of air pollution and fire together with a reanalysis of published data from a subtropical system. The results suggest current carbon stock estimates are positively biased, particularly for low-organic-content sandy seagrass environs, by 18 ± 3% (±95% confidence interval) and 43 ± 21% (±95% CI) for the temperate and tropical regions respectively. The higher BC fractions appear to originate from atmospheric deposition and substantially enrich the relatively low TOC fraction within these environs.

  10. ESTIMATION OF IRREVERSIBLE DAMAGEABILITY AT FATIGUE OF CARBON STEEL

    Directory of Open Access Journals (Sweden)

    I. O. Vakulenko

    2014-04-01

    Full Text Available Purpose. Damageability estimation of carbon steel in the conditions of cyclic loading. Methodology. The steel fragments of railway wheel rim and rail head served as material for research with chemical composition 0.65 % С, 0.67 % Mn, 0.3 % Si, 0.027 % P, 0.028 % S и 0.7 % C, 0.82 % Mn, 0.56 % Si, 0.025 % P, 0.029 % S accordingly. The microstructure of tested steels corresponded to the state of metal after a hot plastic deformation. The fatigue research was conducted in the conditions of symmetric bend using the proof-of-concept machine of type «Saturn-10». Full Wohler diagrams and the lines corresponding to forming of sub-and micro cracks were constructed. The distribution analysis of internal stresses in the metal under cyclic loading was carried out using the microhardness tester of PMT-3 type.Findings. On the basis of fatigue curves for high-carbon steels analysis the positions of borders dividing the areas of convertible and irreversible damages were determined. The article shows that with the growth of carbon concentration in the steel at invariability of the structural state an increase of fatigue limit is observed. At the same time the acceleration of processes, which determine transition terms from the stage of forming of submicrocracks to the microcracks occurs. The research of microhardness distribution in the metal after destruction confirmed the nature of carbon amount influence on the carbon steel characteristics. Originality. Regardless on the stages of breakdown site forming the carbon steels behavior at a fatigue is determined by the ration between the processes of strengthening and softening. At a cyclic loading the heterogeneity of internal stresses distribution decreases with the increase of distance from the destruction surface. Analysis of metal internal restructuring processes at fatigue loading made it possible to determine that at the stages prior to incubation period in the metal microvolumes the cells are already

  11. Estimating Terrestrial Wood Biomass from Observed Concentrations of Atmospheric Carbon Dioxide

    NARCIS (Netherlands)

    Schaefer, K. M.; Peters, W.; Carvalhais, N.; van der Werf, G.; Miller, J.

    2008-01-01

    We estimate terrestrial disequilibrium state and wood biomass from observed concentrations of atmospheric CO2 using the CarbonTracker system coupled to the SiBCASA biophysical model. Starting with a priori estimates of carbon flux from the land, ocean, and fossil fuels, CarbonTracker estimates net

  12. Upscaling Our Approach to Peatland Carbon Sequestration: Remote Sensing as a Tool for Carbon Flux Estimation.

    Science.gov (United States)

    Lees, K.; Khomik, M.; Clark, J. M.; Quaife, T. L.; Artz, R.

    2017-12-01

    Peatlands are an important part of the Earth's carbon cycle, comprising approximately a third of the global terrestrial carbon store. However, peatlands are sensitive to climatic change and human mismanagement, and many are now degraded and acting as carbon sources. Restoration work is being undertaken at many sites around the world, but monitoring the success of these schemes can be difficult and costly using traditional methods. A landscape-scale alternative is to use satellite data in order to assess the condition of peatlands and estimate carbon fluxes. This work focuses on study sites in Northern Scotland, where parts of the largest blanket bog in Europe are being restored from forest plantations. A combination of laboratory and fieldwork has been used to assess the Net Ecosystem Exchange (NEE), Gross Primary Productivity (GPP) and respiration of peatland sites in different conditions, and the climatic vulnerability of key peat-forming Sphagnum species. The results from these studies have been compared with spectral data in order to evaluate the extent to which remote sensing can function as a source of information for peatland health and carbon flux models. This work considers particularly the effects of scale in calculating peatland carbon flux. Flux data includes chamber and eddy covariance measurements of carbon dioxide, and radiometric observations include both handheld spectroradiometer results and satellite images. Results suggest that despite the small-scale heterogeneity and unique ecosystem factors in blanket bogs, remote sensing can be a useful tool in monitoring peatland health and carbon sequestration. In particular, this study gives unique insights into the relationships between peatland vegetation, carbon flux and spectral reflectance.

  13. Seasonal dynamics of soil CO2 efflux and soil profile CO2 concentrations in arboretum of Moscow botanical garden

    Science.gov (United States)

    Goncharova, Olga; Udovenko, Maria; Matyshak, Georgy

    2016-04-01

    To analyse and predict recent and future climate change on a global scale exchange processes of greenhouse gases - primarily carbon dioxide - over various ecosystems are of rising interest. In order to upscale land-use dependent sources and sinks of CO2, knowledge of the local variability of carbon fluxes is needed. Among terrestrial ecosystems, urban areas play an important role because most of anthropogenic emissions of carbon dioxide originate from these areas. On the other hand, urban soils have the potential to store large amounts of soil organic carbon and, thus, contribute to mitigating increases in atmospheric CO2 concentrations. Research objectives: 1) estimate the seasonal dynamics of carbon dioxide production (emission - closed chamber technique and profile concentration - soil air sampling tubes method) by soils of Moscow State University Botanical Garden Arboretum planted with Picea obovata and Pinus sylvestris, 1) identification the factors that control CO2 production. The study was conducted with 1-2 weeks intervals between October 2013 and November 2015 at two sites. Carbon dioxide soil surface efflux during the year ranged from 0 to 800 mgCO2/(m2hr). Efflux values above 0 mgCO2/(m2hr) was observed during the all cold period except for only 3 weeks. Soil CO2 concentration ranged from 1600-3000 ppm in upper 10-cm layer to 10000-40000 ppm at a depth of 60 cm. The maximum concentrations of CO2 were recorded in late winter and late summer. We associate it with high biological activity (both heterotrophic and autotrophic) during the summer, and with physical gas jamming in the winter. The high value of annual CO2 production of the studied soils is caused by high organic matter content, slightly alkaline reaction, good structure and texture of urban soils. Differences in soil CO2 production by spruce and pine urban forest soils (in the pine forest 1.5-2.0 times higher) are caused by urban soil profiles construction, but not temperature regimes. Seasonal

  14. Variation in foliar respiration and wood CO2 efflux rates among species and canopy layers in a wet tropical forest.

    Science.gov (United States)

    Asao, Shinichi; Bedoya-Arrieta, Ricardo; Ryan, Michael G

    2015-02-01

    As tropical forests respond to environmental change, autotrophic respiration may consume a greater proportion of carbon fixed in photosynthesis at the expense of growth, potentially turning the forests into a carbon source. Predicting such a response requires that we measure and place autotrophic respiration in a complete carbon budget, but extrapolating measurements of autotrophic respiration from chambers to ecosystem remains a challenge. High plant species diversity and complex canopy structure may cause respiration rates to vary and measurements that do not account for this complexity may introduce bias in extrapolation more detrimental than uncertainty. Using experimental plantations of four native tree species with two canopy layers, we examined whether species and canopy layers vary in foliar respiration and wood CO2 efflux and whether the variation relates to commonly used scalars of mass, nitrogen (N), photosynthetic capacity and wood size. Foliar respiration rate varied threefold between canopy layers, ∼0.74 μmol m(-2) s(-1) in the overstory and ∼0.25 μmol m(-2) s(-1) in the understory, but little among species. Leaf mass per area, N and photosynthetic capacity explained some of the variation, but height explained more. Chamber measurements of foliar respiration thus can be extrapolated to the canopy with rates and leaf area specific to each canopy layer or height class. If area-based rates are sampled across canopy layers, the area-based rate may be regressed against leaf mass per area to derive the slope (per mass rate) to extrapolate to the canopy using the total leaf mass. Wood CO2 efflux varied 1.0-1.6 μmol m(-2) s(-1) for overstory trees and 0.6-0.9 μmol m(-2) s(-1) for understory species. The variation in wood CO2 efflux rate was mostly related to wood size, and little to species, canopy layer or height. Mean wood CO2 efflux rate per surface area, derived by regressing CO2 efflux per mass against the ratio of surface

  15. Model comparisons for estimating carbon emissions from North American wildland fire

    Science.gov (United States)

    Nancy H.F. French; William J. de Groot; Liza K. Jenkins; Brendan M. Rogers; Ernesto Alvarado; Brian Amiro; Bernardus De Jong; Scott Goetz; Elizabeth Hoy; Edward Hyer; Robert Keane; B.E. Law; Donald McKenzie; Steven G. McNulty; Roger Ottmar; Diego R. Perez-Salicrup; James Randerson; Kevin M. Robertson; Merritt. Turetsky

    2011-01-01

    Research activities focused on estimating the direct emissions of carbon from wildland fires across North America are reviewed as part of the North American Carbon Program disturbance synthesis. A comparison of methods to estimate the loss of carbon from the terrestrial biosphere to the atmosphere from wildland fires is presented. Published studies on emissions from...

  16. Soil CO2 concentrations and efflux dynamics of a tree island in the Pantanal wetland

    Science.gov (United States)

    Lathuillière, Michael J.; Pinto, Osvaldo B.; Johnson, Mark S.; Jassal, Rachhpal S.; Dalmagro, Higo J.; Leite, Nei K.; Speratti, Alicia B.; Krampe, Daniela; Couto, Eduardo G.

    2017-08-01

    The Pantanal is the largest tropical wetland on the planet, and yet little information is available on the biome's carbon cycle. We used an automatic station to measure soil CO2 concentrations and oxidation-reduction potential over the 2014 and 2015 flood cycles of a tree island in the Pantanal that is immune to inundation during the wetland's annual flooding. The soil CO2 concentration profile was then used to estimate soil CO2 efflux over the two periods. In 2014, subsurface soil saturation at 0.30 m depth created conditions in that layer that led to CO2 buildup close to 200,000 ppm and soil oxidation-reduction potential below -300 mV, conditions that were not repeated in 2015 due to annual variability in soil saturation at the site. Mean CO2 efflux over the 2015 flood cycle was 0.023 ± 0.103 mg CO2-C m-2 s-1 representing a total annual efflux of 593 ± 2690 mg CO2-C m-2 y-1. Unlike a nearby tree island site that experiences full inundation during the wet season, here the soil dried quickly following repeated rain events throughout the year, which led to the release of CO2 pulses from the soil. This study highlights not only the complexity and heterogeneity in the Pantanal's carbon balance based on differences in topography, flood cycles, and vegetation but also the challenges of applying the gradient method in the Pantanal due to deviations from steady state conditions.

  17. Updated estimate of carbon balance on Russian territory

    Energy Technology Data Exchange (ETDEWEB)

    Kurganova, I. N.; Kudeyarov, V. N.; Gerenyu, V. O. Lopes de (Institute of Physicochemical and Biological Problems in Soil Science, RAS, Pushchino (Russian Federation)), e-mail: ikurg@mail.ru

    2010-11-15

    The land use system in Russia changed considerably after 1990: 30.2 million ha of croplands were abandoned. Based on the own field investigations that were carried out in abandoned lands of different age (Luvic Phaeozems, deciduous forest zone; Moscow region, 54 deg 50' N, 37 deg 37' E), it has been shown that after 4.5 yr of abandonment, the former croplands acted as a stable sink of CO{sub 2}. The net ecosystem production (NEP) in the post-agrogenic ecosystems averaged 245 +- 73gCm-2 yr-1 for the first 15 yr after land use change that corresponds to an estimated 74 +- 22 Tg C yr-1 for the total area of abandoned lands in Russian Federation. Currently, the Russian territory acts as an absolute sink of atmospheric CO{sub 2} at a rate about 0.90 Pg C yr-1. Using three different approaches, it was demonstrated that after 1990, the carbon sequestration in Russian soils (0.20 cm layer) has averaged 34 +- 2.2 Tg C yr-1. This soil C forms net biome production (NBP) where carbon lifetime is much longer than in 'Kyoto forests'. Thus, the post-agrogenic ecosystems in Russia provide with the additional CO{sub 2} sink in NEP and NBP that could annually compensate about 25% of the current fossil fuel emissions in the Russian Federation

  18. Estimates of increased black carbon emissions from electrostatic precipitators during powdered activated carbon injection for mercury emissions control.

    Science.gov (United States)

    Clack, Herek L

    2012-07-03

    The behavior of mercury sorbents within electrostatic precipitators (ESPs) is not well-understood, despite a decade or more of full-scale testing. Recent laboratory results suggest that powdered activated carbon exhibits somewhat different collection behavior than fly ash in an ESP and particulate filters located at the outlet of ESPs have shown evidence of powdered activated carbon penetration during full-scale tests of sorbent injection for mercury emissions control. The present analysis considers a range of assumed differential ESP collection efficiencies for powdered activated carbon as compared to fly ash. Estimated emission rates of submicrometer powdered activated carbon are compared to estimated emission rates of particulate carbon on submicrometer fly ash, each corresponding to its respective collection efficiency. To the extent that any emitted powdered activated carbon exhibits size and optical characteristics similar to black carbon, such emissions could effectively constitute an increase in black carbon emissions from coal-based stationary power generation. The results reveal that even for the low injection rates associated with chemically impregnated carbons, submicrometer particulate carbon emissions can easily double if the submicrometer fraction of the native fly ash has a low carbon content. Increasing sorbent injection rates, larger collection efficiency differentials as compared to fly ash, and decreasing sorbent particle size all lead to increases in the estimated submicrometer particulate carbon emissions.

  19. Methodology proposal for estimation of carbon storage in urban green areas

    NARCIS (Netherlands)

    Schröder, C.; Mancosu, E.; Roerink, G.J.

    2013-01-01

    Methodology proposal for estimation of carbon storage in urban green areas; final report. Subtitle: Final report of task Task 262-5-6 "Carbon sequestration in urban green infrastructure" Project manager Marie Cugny-Seguin. Date: 15-10-2013

  20. A multichannel automated chamber system for continuous measurement of forest soil CO2 efflux

    International Nuclear Information System (INIS)

    Liang, N.; Inoue, G.; Fujinuma, Y.

    2003-01-01

    Development of a fast-response multi-chamber system for measuring soil-surface carbon dioxide efflux is described. The sixteen-chamber automated system continuously monitors surface carbon dioxide efflux at different locations within a forest ecosystem using a single infrared gas analyzer that successively measures gas samples from each of the sixteen chambers. The chambers have lids that open and close automatically, and are connected in parallel to the single carbon dioxide analyzer which is equipped with a sixteen-channel gas sampler. Air is withdrawn continuously from the inlets and outlets of each chamber and fed sequentially to the gas analyzer. Using this instrument, surface carbon dioxide efflux was measured in a 40-year old pine forest during a three-month period (February to May) in 2001. Results showed a steady increase in mean carbon dioxide efflux during the period. A statistically significant correlation between soil-surface carbon dioxide efflux and surface temperature was also established. Spatial variation of carbon dioxide efflux was found to be higher in the non-growing season than in the growing season. It was concluded that the multi-channel automated chamber system can provide large amounts of high quality data on soil carbon dioxide efflux over a large surface area and simultaneously evaluate both spatial and temporal variation. The system uses a relatively small amount of power (70 W maximum) which can be further reduced (to 15 W) by minimizing the pressure difference between inside and outside the chamber. The system requires no maintenance other than the calibration of the gas analyzer and measurement of the flow rate through the chambers. 34 refs., 8 figs

  1. Efflux pumps as antimicrobial resistance mechanisms.

    Science.gov (United States)

    Poole, Keith

    2007-01-01

    Antibiotic resistance continues to hamper antimicrobial chemotherapy of infectious disease, and while biocide resistance outside of the laboratory is as yet unrealized, in vitro and in vivo episodes of reduced biocide susceptibility are not uncommon. Efflux mechanisms, both drug-specific and multidrug, are important determinants of intrinsic and/or acquired resistance to these antimicrobials in important human pathogens. Multidrug efflux mechanisms are generally chromosome-encoded, with their expression typically resultant from mutations in regulatory genes, while drug-specific efflux mechanisms are encoded by mobile genetic elements whose acquisition is sufficient for resistance. While it has been suggested that drug-specific efflux systems originated from efflux determinants of self-protection in antibiotic-producing Actinomycetes, chromosomal multidrug efflux determinants, at least in Gram-negative bacteria, are appreciated as having an intended housekeeping function unrelated to drug export and resistance. Thus, it will be important to elucidate the intended natural function of these efflux mechanisms in order, for example, to anticipate environmental conditions or circumstances that might promote their expression and, so, compromise antimicrobial chemotherapy. Given the clinical significance of antimicrobial exporters, it is clear that efflux must be considered in formulating strategies for treatment of drug-resistant infections, both in the development of new agents, for example, less impacted by efflux or in targeting efflux directly with efflux inhibitors.

  2. Biomass models to estimate carbon stocks for hardwood tree species

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz-Peinado, R.; Montero, G.; Rio, M. del

    2012-11-01

    To estimate forest carbon pools from forest inventories it is necessary to have biomass models or biomass expansion factors. In this study, tree biomass models were developed for the main hardwood forest species in Spain: Alnus glutinosa, Castanea sativa, Ceratonia siliqua, Eucalyptus globulus, Fagus sylvatica, Fraxinus angustifolia, Olea europaea var. sylvestris, Populus x euramericana, Quercus canariensis, Quercus faginea, Quercus ilex, Quercus pyrenaica and Quercus suber. Different tree biomass components were considered: stem with bark, branches of different sizes, above and belowground biomass. For each species, a system of equations was fitted using seemingly unrelated regression, fulfilling the additivity property between biomass components. Diameter and total height were explored as independent variables. All models included tree diameter whereas for the majority of species, total height was only considered in the stem biomass models and in some of the branch models. The comparison of the new biomass models with previous models fitted separately for each tree component indicated an improvement in the accuracy of the models. A mean reduction of 20% in the root mean square error and a mean increase in the model efficiency of 7% in comparison with recently published models. So, the fitted models allow estimating more accurately the biomass stock in hardwood species from the Spanish National Forest Inventory data. (Author) 45 refs.

  3. Estimation of Regional Carbon Balance from Atmospheric Observations

    Science.gov (United States)

    Denning, S.; Uliasz, M.; Skidmore, J.

    2002-12-01

    Variations in the concentration of CO2 and other trace gases in time and space contain information about sources and sinks at regional scales. Several methods have been developed to quantitatively extract this information from atmospheric measurements. Mass-balance techniques depend on the ability to repeatedly sample the same mass of air, which involves careful attention to airmass trajectories. Inverse and adjoint techniques rely on decomposition of the source field into quasi-independent "basis functions" that are propagated through transport models and then used to synthesize optimal linear combinations that best match observations. A recently proposed method for regional flux estimation from continuous measurements at tall towers relies on time-mean vertical gradients, and requires careful trajectory analysis to map the estimates onto regional ecosystems. Each of these techniques is likely to be applied to measurements made during the North American Carbon Program. We have also explored the use of Bayesian synthesis inversion at regional scales, using a Lagrangian particle dispersion model driven by mesoscale transport fields. Influence functions were calculated for each hypothetical observation in a realistic diurnally-varying flow. These influence functions were then treated as basis functions for the purpose of separate inversions for daytime photosynthesis and 24-hour mean ecosystem respiration. Our results highlight the importance of estimating CO2 fluxes through the lateral boundaries of the model. Respiration fluxes were well constrained by one or two hypothetical towers, regardless of inflow fluxes. Time-varying assimilation fluxes were less well constrained, and much more dependent on knowledge of inflow fluxes. The small net difference between respiration and photosynthesis was the most difficult to determine, being extremely sensitive to knowledge of inflow fluxes. Finally, we explored the feasibility of directly incorporating mid-day concentration

  4. Peptide mediators of cholesterol efflux

    Energy Technology Data Exchange (ETDEWEB)

    Bielicki, John K.; Johansson, Jan

    2013-04-09

    The present invention provides a family of non-naturally occurring polypeptides having cholesterol efflux activity that parallels that of full-length apolipoproteins (e.g., Apo AI and Apo E), and having high selectivity for ABAC1 that parallels that of full-length apolipoproteins. The invention also provides compositions comprising such polypeptides, methods of identifying, screening and synthesizing such polypeptides, and methods of treating, preventing or diagnosing diseases and disorders associated with dyslipidemia, hypercholesterolemia and inflammation.

  5. Consequences of alternative tree-level biomass estimation procedures on U.S. forest carbon stock estimates

    Science.gov (United States)

    Grant M. Domke; Christopher W. Woodall; James E. Smith; James A. Westfall; Ronald E. McRoberts

    2012-01-01

    Forest ecosystems are the largest terrestrial carbon sink on earth and their management has been recognized as a relatively cost-effective strategy for offsetting greenhouse gas emissions. Forest carbon stocks in the U.S. are estimated using data from the USDA Forest Service, Forest Inventory and Analysis (FIA) program. In an attempt to balance accuracy with...

  6. Mind the gap: non-biological processes contributing to soil CO2 efflux.

    Science.gov (United States)

    Rey, Ana

    2015-05-01

    Widespread recognition of the importance of soil CO2 efflux as a major source of CO2 to the atmosphere has led to active research. A large soil respiration database and recent reviews have compiled data, methods, and current challenges. This study highlights some deficiencies for a proper understanding of soil CO2 efflux focusing on processes of soil CO2 production and transport that have not received enough attention in the current soil respiration literature. It has mostly been assumed that soil CO2 efflux is the result of biological processes (i.e. soil respiration), but recent studies demonstrate that pedochemical and geological processes, such as geothermal and volcanic CO2 degassing, are potentially important in some areas. Besides the microbial decomposition of litter, solar radiation is responsible for photodegradation or photochemical degradation of litter. Diffusion is considered to be the main mechanism of CO2 transport in the soil, but changes in atmospheric pressure and thermal convection may also be important mechanisms driving soil CO2 efflux greater than diffusion under certain conditions. Lateral fluxes of carbon as dissolved organic and inorganic carbon occur and may cause an underestimation of soil CO2 efflux. Traditionally soil CO2 efflux has been measured with accumulation chambers assuming that the main transport mechanism is diffusion. New techniques are available such as improved automated chambers, CO2 concentration profiles and isotopic techniques that may help to elucidate the sources of carbon from soils. We need to develop specific and standardized methods for different CO2 sources to quantify this flux on a global scale. Biogeochemical models should include biological and non-biological CO2 production processes before we can predict the response of soil CO2 efflux to climate change. Improving our understanding of the processes involved in soil CO2 efflux should be a research priority given the importance of this flux in the global

  7. Spatial and temporal variation of CO2 efflux along a disturbance gradient in a miombo woodland in Western Zambia

    Directory of Open Access Journals (Sweden)

    M. M. Mukelabai

    2011-01-01

    Full Text Available Carbon dioxide efflux from the soil surface was measured over a period of several weeks within a heterogeneous Brachystegia spp. dominated miombo woodland in Western Zambia. The objectives were to examine spatial and temporal variation of soil respiration along a disturbance gradient from a protected forest reserve to a cut, burned, and grazed area outside, and to relate the flux to various abiotic and biotic drivers. The highest daily mean fluxes (around 12 μmol CO2 m−2 s−1 were measured in the protected forest in the wet season and lowest daily mean fluxes (around 1 μmol CO2 m−2 s−1 in the most disturbed area during the dry season. Diurnal variation of soil respiration was closely correlated with soil temperature. The combination of soil water content and soil temperature was found to be the main driving factor at seasonal time scale. There was a 75% decrease in soil CO2 efflux during the dry season and a 20% difference in peak soil respiratory flux measured in 2008 and 2009. Spatial variation of CO2 efflux was positively related to total soil carbon content in the undisturbed area but not at the disturbed site. Coefficients of variation of efflux rates between plots decreased towards the core zone of the protected forest reserve. Normalized soil respiration values did not vary significantly along the disturbance gradient. Spatial variation of respiration did not show a clear distinction between the disturbed and undisturbed sites and could not be explained by variables such as leaf area index. In contrast, within plot variability of soil respiration was explained by soil organic carbon content. Three different approaches to calculate total ecosystem respiration (Reco from eddy covariance measurements were compared to two bottom-up estimates of Reco obtained from chambers measurements of soil- and leaf respiration which differed in the consideration of spatial heterogeneity. The consideration of spatial variability resulted only in

  8. Internal respiration of Amazon tree stems greatly exceeds external CO2 efflux

    Directory of Open Access Journals (Sweden)

    J. Q. Chambers

    2012-12-01

    Full Text Available Respiration in tree stems is an important component of forest carbon balance. The rate of CO2 efflux from the stem has often been assumed to be a measure of stem respiration. However, recent work in temperate forests has demonstrated that stem CO2 efflux can either overestimate or underestimate respiration rate because of emission or removal of CO2 by transport in xylem water. Here, we studied gas exchange from stems of tropical forest trees using a new approach to better understand respiration in an ecosystem that plays a key role in the global carbon cycle. Our main questions were (1 is internal CO2 transport important in tropical trees, and, if so, (2 does this transport result in net release of CO2 respired in the roots at the stem, or does it cause the opposite effect of net removal of stem-respired CO2? To answer these questions, we measured the ratio of stem CO2 efflux to O2 influx. This ratio, defined here as apparent respiratory quotient (ARQ, is expected to equal 1.0 if carbohydrates are the substrate for respiration, and the net transport of CO2 in the xylem water is negligible. Using a stem chamber approach to quantifying ARQ, we found values of 0.66 ± 0.18. These low ARQ values indicate that a large portion of respired CO2 (~ 35% is not emitted locally, and is probably transported upward in the stem. ARQ values of 0.21 ± 0.10 were found for the steady-state gas concentration within the stem, sampled by in-stem equilibration probes. These lower values may result from the proximity to the xylem water stream. In contrast, we found ARQ values of 1.00 ± 0.13 for soil respiration. Our results indicate the existence of a considerable internal flux of CO2 in the stems of tropical trees. If the transported CO2 is used in the canopy as a substrate for photosynthesis, it could account for up to 10% of the C fixed by the tree, and perhaps serve as a mechanism that buffers the response of the tree to changing CO2 levels. Our results also

  9. Sources of CO{sub 2} efflux from soil and review of partitioning methods

    Energy Technology Data Exchange (ETDEWEB)

    Kuzyakov, Y. [University of Hohenheim, Stuttgart (Germany). Institute of Soil Science and Land Evaluation

    2006-03-15

    Five main biogenic sources of CO{sub 2} efflux from soils have been distinguished and described according to their turnover rates and the mean residence time of carbon. They are root respiration, rhizomicrobial respiration, decomposition of plant residues, the priming effect induced by root exudation or by addition of plant residues, and basal respiration by microbial decomposition of soil organic matter (SOM). These sources can be grouped in several combinations to summarize CO{sub 2} efflux from the soil including: root-derived CO{sub 2}, plant-derived CO{sub 2}, SOM-derived CO{sub 2}, rhizosphere respiration, heterotrophic microbial respiration (respiration by heterotrophs), and respiration by autotrophs. These distinctions are important because without separation of SOM-derived CO{sub 2} from plant-derived CO{sub 2}, measurements of total soil respiration have very limited value for evaluation of the soil as a source or sink of atmospheric CO{sub 2} and for interpreting the sources of CO{sub 2} and the fate of carbon within soils and ecosystems. Additionally, the processes linked to the five sources of CO{sub 2} efflux from soil have various responses to environmental variables and consequently to global warming. This review describes the basic principles and assumptions of the following methods which allow SOM-derived and root-derived CO{sub 2} efflux to be separated under laboratory and field conditions: root exclusion techniques, shading and clipping, tree girdling, regression, component integration, excised roots and in situ root respiration; continuous and pulse labeling, {sup 13}C natural abundance and FACE, and radiocarbon dating and bomb-{sup 14}C. A short sections cover the separation of the respiration of autotrophs and that of heterotrophs, i.e. the separation of actual root respiration from microbial respiration, as well as methods allowing the amount of CO{sub 2} evolved by decomposition of plant residues and by priming effects to be estimated. All

  10. Sources of CO2 efflux from soil and review of partitioning methods

    International Nuclear Information System (INIS)

    Kuzyakov, Y.

    2006-01-01

    Five main biogenic sources of CO 2 efflux from soils have been distinguished and described according to their turnover rates and the mean residence time of carbon. They are root respiration, rhizomicrobial respiration, decomposition of plant residues, the priming effect induced by root exudation or by addition of plant residues, and basal respiration by microbial decomposition of soil organic matter (SOM). These sources can be grouped in several combinations to summarize CO 2 efflux from the soil including: root-derived CO 2 , plant-derived CO 2 , SOM-derived CO 2 , rhizosphere respiration, heterotrophic microbial respiration (respiration by heterotrophs), and respiration by autotrophs. These distinctions are important because without separation of SOM-derived CO 2 from plant-derived CO 2 , measurements of total soil respiration have very limited value for evaluation of the soil as a source or sink of atmospheric CO 2 and for interpreting the sources of CO 2 and the fate of carbon within soils and ecosystems. Additionally, the processes linked to the five sources of CO 2 efflux from soil have various responses to environmental variables and consequently to global warming. This review describes the basic principles and assumptions of the following methods which allow SOM-derived and root-derived CO 2 efflux to be separated under laboratory and field conditions: root exclusion techniques, shading and clipping, tree girdling, regression, component integration, excised roots and in situ root respiration; continuous and pulse labeling, 13 C natural abundance and FACE, and radiocarbon dating and bomb- 14 C. A short sections cover the separation of the respiration of autotrophs and that of heterotrophs, i.e. the separation of actual root respiration from microbial respiration, as well as methods allowing the amount of CO 2 evolved by decomposition of plant residues and by priming effects to be estimated. All these methods have been evaluated according to their inherent

  11. CO2 efflux from soils with seasonal water repellency

    Science.gov (United States)

    Urbanek, Emilia; Doerr, Stefan H.

    2017-10-01

    Soil carbon dioxide (CO2) emissions are strongly dependent on pore water distribution, which in turn can be modified by reduced wettability. Many soils around the world are affected by soil water repellency (SWR), which reduces infiltration and results in diverse moisture distribution. SWR is temporally variable and soils can change from wettable to water-repellent and vice versa throughout the year. Effects of SWR on soil carbon (C) dynamics, and specifically on CO2 efflux, have only been studied in a few laboratory experiments and hence remain poorly understood. Existing studies suggest soil respiration is reduced with increasing severity of SWR, but the responses of soil CO2 efflux to varying water distribution created by SWR are not yet known.Here we report on the first field-based study that tests whether SWR indeed reduces soil CO2 efflux, based on in situ measurements carried out over three consecutive years at a grassland and pine forest sites under the humid temperate climate of the UK.Soil CO2 efflux was indeed very low on occasions when soil exhibited consistently high SWR and low soil moisture following long dry spells. Low CO2 efflux was also observed when SWR was absent, in spring and late autumn when soil temperatures were low, but also in summer when SWR was reduced by frequent rainfall events. The highest CO2 efflux occurred not when soil was wettable, but when SWR, and thus soil moisture, was spatially patchy, a pattern observed for the majority of the measurement period. Patchiness of SWR is likely to have created zones with two different characteristics related to CO2 production and transport. Zones with wettable soil or low persistence of SWR with higher proportion of water-filled pores are expected to provide water with high nutrient concentration resulting in higher microbial activity and CO2 production. Soil zones with high SWR persistence, on the other hand, are dominated by air-filled pores with low microbial activity, but facilitating O2

  12. Estimating soil labile organic carbon and potential turnover rates using a sequential fumigation–incubation procedure.

    Science.gov (United States)

    X.M. Zoua; H.H. Ruanc; Y. Fua; X.D. Yanga; L.Q. Sha

    2005-01-01

    Labile carbon is the fraction of soil organic carbon with most rapid turnover times and its oxidation drives the flux of CO2 between soils and atmosphere. Available chemical and physical fractionation methods for estimating soil labile organic carbon are indirect and lack a clear biological definition. We have modified the well-established Jenkinson and Powlson’s...

  13. Forest inventory-based estimation of carbon stocks and flux in California forests in 1990.

    Science.gov (United States)

    Jeremy S. Fried; Xiaoping. Zhou

    2008-01-01

    Estimates of forest carbon stores and flux for California circa 1990 were modeled from forest inventory data in support of California’s legislatively mandated greenhouse gas inventory. Reliable estimates of live-tree carbon stores and flux on timberlands outside of national forest could be calculated from periodic inventory data collected in the 1980s and 1990s;...

  14. ESTIMATION OF CARBON SEQUESTRATION BY RUSSIAN FORESTS: GEOSPATIAL ISSUE

    Directory of Open Access Journals (Sweden)

    N. V. Malysheva

    2017-01-01

    Full Text Available Сategories of carbon sequestration assessment for Russian forests are identified by GIS toolkit. Those are uniform by bioclimatic and site-specific conditions strata corresponding to modern version of bioclimatic forest district division. Stratification of forests at early stage substantially reduces the ambiguity of the evaluation because phytomass conversion sequestration capacity and expansion factor dependent on site-specific condition for calculating of forest carbon sink are absolutely necessary. Forest management units were linked to strata. Biomass conversion and expansion factor for forest carbon sink assessment linked to the strata were recalculated for forest management units. All operations were carried out with GIS analytical toolkit due to accessible functionalities. Units for forest carbon storage inventory and forest carbon balance calculation were localized. Production capacity parameters and forest carbon sequestration capacity have been visualized on maps complied by ArcGIS. Based on spatially-explicit information, we have found out that the greatest annual rates of forest’s carbon accumulation in Russian forests fall into mixed coniferous-deciduous forests of European-Ural part of Russia to Kaliningrad, Smolensk and Briansk Regions, coniferous-deciduous forests close to the boundary of Khabarovsk Region and Primorskij Kray in the Far East, as well as separate forest management units of Kabardino-Balkariya NorthCaucasian mountain area. The geospatial visualization of carbon sequestration by Russian forests and carbon balance assessment has been given.

  15. Evaluation of black carbon estimations in global aerosol models

    Directory of Open Access Journals (Sweden)

    Y. Zhao

    2009-11-01

    Full Text Available We evaluate black carbon (BC model predictions from the AeroCom model intercomparison project by considering the diversity among year 2000 model simulations and comparing model predictions with available measurements. These model-measurement intercomparisons include BC surface and aircraft concentrations, aerosol absorption optical depth (AAOD retrievals from AERONET and Ozone Monitoring Instrument (OMI and BC column estimations based on AERONET. In regions other than Asia, most models are biased high compared to surface concentration measurements. However compared with (column AAOD or BC burden retreivals, the models are generally biased low. The average ratio of model to retrieved AAOD is less than 0.7 in South American and 0.6 in African biomass burning regions; both of these regions lack surface concentration measurements. In Asia the average model to observed ratio is 0.7 for AAOD and 0.5 for BC surface concentrations. Compared with aircraft measurements over the Americas at latitudes between 0 and 50N, the average model is a factor of 8 larger than observed, and most models exceed the measured BC standard deviation in the mid to upper troposphere. At higher latitudes the average model to aircraft BC ratio is 0.4 and models underestimate the observed BC loading in the lower and middle troposphere associated with springtime Arctic haze. Low model bias for AAOD but overestimation of surface and upper atmospheric BC concentrations at lower latitudes suggests that most models are underestimating BC absorption and should improve estimates for refractive index, particle size, and optical effects of BC coating. Retrieval uncertainties and/or differences with model diagnostic treatment may also contribute to the model-measurement disparity. Largest AeroCom model diversity occurred in northern Eurasia and the remote Arctic, regions influenced by anthropogenic sources. Changing emissions, aging, removal, or optical properties within a single model

  16. Relationship between insulin release and 65zinc efflux from rat pancreatic islets maintained in tissue culture

    International Nuclear Information System (INIS)

    Formby, B.; Schmid-Formby, F.; Grodsky, G.M.

    1984-01-01

    In short-term batch-incubation or perfusion experiments, we studied insulin release and associated 65 Zn efflux from rat pancreatic islets loaded with 65 Zn by 24-h tissue culture in low-glucose medium. The fractional basal insulin release and 65 Zn efflux were 0.4% and 3% of total content/h/islet, respectively. Thus, basal 65 Zn efflux was much greater than that to be accounted for if zinc was released proportionally with insulin release only; extragranular zinc flux was suggested. Two millimolar glucose, with or without 1 mM 3-isobutyl-1-methylxanthine (IBMX), affected neither insulin release nor associated 65 Zn efflux. Twenty-five millimolar glucose produced a significant threefold increase in insulin release above baseline, but somewhat decreased 65 Zn efflux at marginal significance. Glucose (25 mM) plus 1 mM IBMX provoked a high increase in insulin release and an associated 30% increase in fractional 65 Zn efflux over basal. Calculations based on previous estimations of 65 Zn distribution and equilibrium with islet zinc indicated that molar zinc efflux was more than sufficient to account for a 2-zinc-insulin hexamer. L-Leucine (2 or 20 mM) plus 1 mM IBMX caused far greater 65 Zn efflux for the amount of insulin released, indicating additional 65 Zn mobilization not directly related to insulin secretion. To evaluate 65 Zn efflux during inhibited insulin secretion, batch incubations were performed in 100% D 2 O or at 27 degrees C, conditions that inhibited insulin release stimulated by high glucose plus IBMX. These agents decreased the 65 Zn efflux far below the basal value (35% and 50%, respectively) and greater than could be accounted for by the attendent inhibition of insulin secretion.(ABSTRACT TRUNCATED AT 250 WORDS)

  17. Inverse carbon dioxide flux estimates for the Netherlands

    Energy Technology Data Exchange (ETDEWEB)

    Meesters, A.G.C.A.; Tolk, L.F.; Dolman, A.J. [Faculty of Earth and Life Sciences, VU University, Amsterdam (Netherlands); Peters, W.; Hutjes, R.W.A.; Vellinga, O.S.; Elbers, J.A. [Department Meteorology and Air Quality, Wageningen University and Research Centre, Wageningen (Netherlands); Vermeulen, A.T. [Biomass, Coal and Environmental Research, Energy research Center of the Netherlands ECN, Petten (Netherlands); Van der Laan, S.; Neubert, R.E.M.; Meijer, H.A.J. [Centre for Isotope Research, Energy and Sustainability Research Institute Groningen, University of Groningen, Groningen (Netherlands)

    2012-10-26

    CO2 fluxes for the Netherlands and surroundings are estimated for the year 2008, from concentration measurements at four towers, using an inverse model. The results are compared to direct CO2 flux measurements by aircraft, for 6 flight tracks over the Netherlands, flown multiple times in each season. We applied the Regional Atmospheric Mesoscale Modeling system (RAMS) coupled to a simple carbon flux scheme (including fossil fuel), which was run at 10 km resolution, and inverted with an Ensemble Kalman Filter. The domain had 6 eco-regions, and inversions were performed for the four seasons separately. Inversion methods with pixel-dependent and -independent parameters for each eco-region were compared. The two inversion methods, in general, yield comparable flux averages for each eco-region and season, whereas the difference from the prior flux may be large. Posterior fluxes co-sampled along the aircraft flight tracks are usually much closer to the observations than the priors, with a comparable performance for both inversion methods, and with best performance for summer and autumn. The inversions showed more negative CO2 fluxes than the priors, though the latter are obtained from a biosphere model optimized using the Fluxnet database, containing observations from more than 200 locations worldwide. The two different crop ecotypes showed very different CO2 uptakes, which was unknown from the priors. The annual-average uptake is practically zero for the grassland class and for one of the cropland classes, whereas the other cropland class had a large net uptake, possibly because of the abundance of maize there.

  18. One strategy for estimating the potential soil carbon storage due to CO2 fertilization

    International Nuclear Information System (INIS)

    Harrison, K.G.; Bonani, G.

    1994-01-01

    Soil radiocarbon measurements can be used to estimate soil carbon turnover rates and inventories. A labile component of soil carbon has the potential to respond to perturbations such as CO 2 fertilization, changing climate, and changing land use. Soil carbon has influenced past and present atmospheric CO 2 levels and will influence future levels. A model is used to calculate the amount of additional carbon stored in soil because of CO 2 fertilization

  19. Estimating Carbon Dynamics in an Intact Lowland Mixed Dipterocarp Forest Using a Forest Carbon Model

    Directory of Open Access Journals (Sweden)

    Jongyeol Lee

    2017-04-01

    Full Text Available Intact dipterocarp forests in Asia act as crucial carbon (C reservoirs, and it is therefore important to investigate the C dynamics in these forests. We estimated C dynamics, together with net ecosystem production (NEP, in an intact tropical dipterocarp forest of Brunei Darussalam. Fifty-four simulation units (plots; 20 m × 20 m were established and initial C stocks were determined via direct field measurement. The C dynamics were annually simulated with a regression model and the Forest Biomass and Dead organic matter Carbon (FBDC model. The initial C stock (Mg C·ha−1 of biomass, litter, dead wood and mineral soil were 213.1 ± 104.8, 2.0 ± 0.8, 31.3 ± 38.8, and 80.7 ± 15.5, respectively. Their annual changes (Mg C·ha−1·year−1 were 3.2 ± 1.1, 0.2 ± 0.2, −3.7 ± 6.1, and −0.3 ± 1.1, respectively. NEP was −0.6 ± 6.1 Mg C·ha−1·year−1, showing large heterogeneity among the plots. The initial C stocks of biomass and dead wood, biomass turnover rates and dead wood decay rates were elucidated as dominant factors determining NEP in a sensitivity analysis. Accordingly, investigation on those input data can constrain an uncertainty in determining NEP in the intact tropical forests.

  20. Soil carbon estimation from eucalyptus grandis using canopy spectra

    African Journals Online (AJOL)

    Mapping soil fertility parameters, such as soil carbon (C), is fundamentally important for forest management and research related to forest growth and climate change. This study seeks to establish the link between Eucalyptus grandis canopy spectra and soil carbon using raw and continuum-removed spectra. Canopy-level ...

  1. Estimation of mechanical properties of single wall carbon nanotubes ...

    Indian Academy of Sciences (India)

    Molecular mechanics; single wall carbon nanotube; mechanical proper- ... Fracture Mechanics); Rossi & Meo 2009). Furthermore, the work carried out by Natsuki & Endo. (2004), Xiao et al (2005) and Sun & Zhao (2005) in the direction of ..... Jin Y and Yuan F G 2003 Simulation of elastic properties of single walled carbon ...

  2. Sustained effects of atmospheric [CO2] and nitrogen availability on forest soil CO2 efflux

    Science.gov (United States)

    A. Christopher Oishi; Sari Palmroth; Kurt H. Johnsen; Heather R. McCarthy; Ram. Oren

    2014-01-01

    Soil CO2 efflux (Fsoil) is the largest source of carbon from forests and reflects primary productivity as well as how carbon is allocated within forest ecosystems. Through early stages of stand development, both elevated [CO2] and availability of soil nitrogen (N; sum of mineralization, deposition, and fixation) have been shown to increase gross primary productivity,...

  3. CO2 supersaturation and net heterotrophy in a tropical estuary (Cochin, India): Influence of anthropogenic effect - Carbon dynamics in tropical estuary

    Digital Repository Service at National Institute of Oceanography (India)

    Gupta, G.V.M.; Thottathil, S.D.; Balachandran, K.K.; Madhu, N.V.; Madeswaran, P.; Nair, S.

    of pCO sub(2) (up to 6000 mu atm) and CO sub(2) effluxes (up to 274 mmolC m sup(-2) d sup(-1)) especially during monsoon. A first-order estimate of the carbon mass balance shows that net production of dissolved inorganic carbon is an order of magnitude...

  4. Above Ground Carbon Stock Estimates of Mangrove Forest Using Worldview-2 Imagery in Teluk Benoa, Bali

    Science.gov (United States)

    Candra, E. D.; Hartono; Wicaksono, P.

    2016-11-01

    Mangrove forests have a role as an absorbent and a carbon sink to a reduction CO2 in the atmosphere. Based on the previous studies found that mangrove forests have the ability to sequestering carbon through photosynthesis and carbon burial of sediment effectively. The value and distribution of carbon stock are important to understand through remote sensing technology. In this study, will estimate the carbon stock using WorldView-2 imagery with and without distinction mangrove species. Worldview-2 is a high resolution image with 2 meters spatial resolution and eight spectral bands. Worldview-2 potential to estimate carbon stock in detail. Vegetation indices such as DVI (Difference Vegetation Index), EVI (Enhanced Vegetation Index), and MRE-SR (Modified Red Edge-Simple Ratio) and field data were modeled to determine the best vegetation indices to estimate carbon stocks. Carbon stock estimated by allometric equation approach specific to each species of mangrove. Worldview-2 imagery to map mangrove species with an accuracy of 80.95%. Total carbon stock estimation results in the study area of 35.349,87 tons of dominant species Rhizophora apiculata, Rhizophora mucronata and Sonneratia alba.

  5. Monitoring and estimating tropical forest carbon stocks: making REDD a reality

    International Nuclear Information System (INIS)

    Gibbs, Holly K; Brown, Sandra; Niles, John O; Foley, Jonathan A

    2007-01-01

    Reducing carbon emissions from deforestation and degradation in developing countries is of central importance in efforts to combat climate change. Key scientific challenges must be addressed to prevent any policy roadblocks. Foremost among the challenges is quantifying nations' carbon emissions from deforestation and forest degradation, which requires information on forest clearing and carbon storage. Here we review a range of methods available to estimate national-level forest carbon stocks in developing countries. While there are no practical methods to directly measure all forest carbon stocks across a country, both ground-based and remote-sensing measurements of forest attributes can be converted into estimates of national carbon stocks using allometric relationships. Here we synthesize, map and update prominent forest biomass carbon databases to create the first complete set of national-level forest carbon stock estimates. These forest carbon estimates expand on the default values recommended by the Intergovernmental Panel on Climate Change's National Greenhouse Gas Inventory Guidelines and provide a range of globally consistent estimates

  6. Carbon dynamics in corn-soybean sequences as estimated from natural carbon-13 abundance

    International Nuclear Information System (INIS)

    Huggins, D.R.; Clapp, C.E.; Allmaras, R.R.; Lamb, J.A.; Layese, M.F.

    1998-01-01

    Carbon flow in terrestrial ecosystems regulates partitioning between soil organic C (SOC) and atmospheric CO2. Our objectives were to assess SOC dynamics using natural 13C abundance in corn (Zea mays L., a C4 species)-soybean [Glycine max (L.) Merr., a C3 species] sequences. Fifteen treatments of continuous corn, continuous soybean, various sequences of corn and soybean, and fallow were initiated in 1981 at Lamberton, MN, on a Webster clay loam (fine-loamy, mixed, mesic Typic Haplaquoll). In 1991, soil and aboveground shoot samples from all treatments were analyzed for total organic C and delta 13C. Carbon inputs, delta 13C, and SOC were integrated into a two-pool model to evaluate C dynamics of corn and soybean. Total SOC was similar across all treatments after 10 yr; however, differences in soil delta 13C occurred between continuous corn (delta 13C = -17.2 per thous and) and continuous soybean (delta 13C = -18.2 per thousand). Modeled C dynamics showed SOC decay rates of 0.011 yr-1 for C4-derived C and 0.007 yr-1 for C3-derived C, and humification rates of 0.16 yr-1 for corn and 0.11 yr-1 for soybean. Decay and humification rates were slightly lower than those found in other Corn Belt studies. Levels of SOC were predicted to decline an additional 7 to 18% with current C inputs from either corn or soybean, respectively. Annual C additions required for SOC maintenance averaged 5.6 Mg C ha-1, 1.4 to 2.1 times greater than previously reported estimates. Controlled variation in natural 13C abundance in corn-soybean rotations during a 10-yr period adequately traced C dynamics

  7. Reduced carbon emission estimates from fossil fuel combustion and cement production in China.

    Science.gov (United States)

    Liu, Zhu; Guan, Dabo; Wei, Wei; Davis, Steven J; Ciais, Philippe; Bai, Jin; Peng, Shushi; Zhang, Qiang; Hubacek, Klaus; Marland, Gregg; Andres, Robert J; Crawford-Brown, Douglas; Lin, Jintai; Zhao, Hongyan; Hong, Chaopeng; Boden, Thomas A; Feng, Kuishuang; Peters, Glen P; Xi, Fengming; Liu, Junguo; Li, Yuan; Zhao, Yu; Zeng, Ning; He, Kebin

    2015-08-20

    Nearly three-quarters of the growth in global carbon emissions from the burning of fossil fuels and cement production between 2010 and 2012 occurred in China. Yet estimates of Chinese emissions remain subject to large uncertainty; inventories of China's total fossil fuel carbon emissions in 2008 differ by 0.3 gigatonnes of carbon, or 15 per cent. The primary sources of this uncertainty are conflicting estimates of energy consumption and emission factors, the latter being uncertain because of very few actual measurements representative of the mix of Chinese fuels. Here we re-evaluate China's carbon emissions using updated and harmonized energy consumption and clinker production data and two new and comprehensive sets of measured emission factors for Chinese coal. We find that total energy consumption in China was 10 per cent higher in 2000-2012 than the value reported by China's national statistics, that emission factors for Chinese coal are on average 40 per cent lower than the default values recommended by the Intergovernmental Panel on Climate Change, and that emissions from China's cement production are 45 per cent less than recent estimates. Altogether, our revised estimate of China's CO2 emissions from fossil fuel combustion and cement production is 2.49 gigatonnes of carbon (2 standard deviations = ±7.3 per cent) in 2013, which is 14 per cent lower than the emissions reported by other prominent inventories. Over the full period 2000 to 2013, our revised estimates are 2.9 gigatonnes of carbon less than previous estimates of China's cumulative carbon emissions. Our findings suggest that overestimation of China's emissions in 2000-2013 may be larger than China's estimated total forest sink in 1990-2007 (2.66 gigatonnes of carbon) or China's land carbon sink in 2000-2009 (2.6 gigatonnes of carbon).

  8. Incorrectly Interpreting the Carbon Mass Balance Technique Leads to Biased Emissions Estimates from Global Vegetation Fires

    Science.gov (United States)

    Surawski, N. C.; Sullivan, A. L.; Roxburgh, S. H.; Meyer, M.; Polglase, P. J.

    2016-12-01

    Vegetation fires are a complex phenomenon and have a range of global impacts including influences on climate. Even though fire is a necessary disturbance for the maintenance of some ecosystems, a range of anthropogenically deleterious consequences are associated with it, such as damage to assets and infrastructure, loss of life, as well as degradation to air quality leading to negative impacts on human health. Estimating carbon emissions from fire relies on a carbon mass balance technique which has evolved with two different interpretations in the fire emissions community. Databases reporting global fire emissions estimates use an approach based on `consumed biomass' which is an approximation to the biogeochemically correct `burnt carbon' approach. Disagreement between the two methods occurs because the `consumed biomass' accounting technique assumes that all burnt carbon is volatilized and emitted. By undertaking a global review of the fraction of burnt carbon emitted to the atmosphere, we show that the `consumed biomass' accounting approach overestimates global carbon emissions by 4.0%, or 100 Teragrams, annually. The required correction is significant and represents 9% of the net global forest carbon sink estimated annually. To correctly partition burnt carbon between that emitted to the atmosphere and that remaining as a post-fire residue requires the post-burn carbon content to be estimated, which is quite often not undertaken in atmospheric emissions studies. To broaden our understanding of ecosystem carbon fluxes, it is recommended that the change in carbon content associated with burnt residues be accounted for. Apart from correctly partitioning burnt carbon between the emitted and residue pools, it enables an accounting approach which can assess the efficacy of fire management operations targeted at sequestering carbon from fire. These findings are particularly relevant for the second commitment period for the Kyoto protocol, since improved landscape fire

  9. Estimation of carbon flow in a Calluna heath system

    International Nuclear Information System (INIS)

    Roesberg, I.; Oevstedal, D.O.; Seljelid, R.; Schreiner, Oe.; Goksoeyr, J.

    1981-01-01

    In a Culluna heath, plots of 1 m 2 were pulse labelled with 14 CO 2 , and the radioactivity in vegetation above ground, roots, litter and soil organic matter followed for almost two years. In a separate experiment, radioactivity in above ground and root respiration and in soil microbial biomass was determined. A kinetic model for the carbon transfer reaction is presented, and shown to give a satisfactory agreement with the experimental data. The results demonstrate that a major part of the assimilated carbon passes through the roots and into the soil, where it is rapidly mineralized. (author)

  10. A simple approach to estimate soil organic carbon and soil co/sub 2/ emission

    International Nuclear Information System (INIS)

    Abbas, F.

    2013-01-01

    SOC (Soil Organic Carbon) and soil CO/sub 2/ (Carbon Dioxide) emission are among the indicator of carbon sequestration and hence global climate change. Researchers in developed countries benefit from advance technologies to estimate C (Carbon) sequestration. However, access to the latest technologies has always been challenging in developing countries to conduct such estimates. This paper presents a simple and comprehensive approach for estimating SOC and soil CO/sub 2/ emission from arable- and forest soils. The approach includes various protocols that can be followed in laboratories of the research organizations or academic institutions equipped with basic research instruments and technology. The protocols involve soil sampling, sample analysis for selected properties, and the use of a worldwide tested Rothamsted carbon turnover model. With this approach, it is possible to quantify SOC and soil CO/sub 2/ emission over short- and long-term basis for global climate change assessment studies. (author)

  11. Estimation of Global 1km-grid Terrestrial Carbon Exchange Part II: Evaluations and Applications

    Science.gov (United States)

    Murakami, K.; Sasai, T.; Kato, S.; Niwa, Y.; Saito, M.; Takagi, H.; Matsunaga, T.; Hiraki, K.; Maksyutov, S. S.; Yokota, T.

    2015-12-01

    Global terrestrial carbon cycle largely depends on a spatial pattern in land cover type, which is heterogeneously-distributed over regional and global scales. Many studies have been trying to reveal distribution of carbon exchanges between terrestrial ecosystems and atmosphere for understanding global carbon cycle dynamics by using terrestrial biosphere models, satellite data, inventory data, and so on. However, most studies remained within several tens of kilometers grid spatial resolution, and the results have not been enough to understand the detailed pattern of carbon exchanges based on ecological community and to evaluate the carbon stocks by forest ecosystems in each countries. Improving the sophistication of spatial resolution is obviously necessary to enhance the accuracy of carbon exchanges. Moreover, the improvement may contribute to global warming awareness, policy makers and other social activities. We show global terrestrial carbon exchanges (net ecosystem production, net primary production, and gross primary production) with 1km-grid resolution. The methodology for these estimations are shown in the 2015 AGU FM poster "Estimation of Global 1km-grid Terrestrial Carbon Exchange Part I: Developing Inputs and Modelling". In this study, we evaluated the carbon exchanges in various regions with other approaches. We used the satellite-driven biosphere model (BEAMS) as our estimations, GOSAT L4A CO2 flux data, NEP retrieved by NICAM and CarbonTracer2013 flux data, for period from Jun 2001 to Dec 2012. The temporal patterns for this period were indicated similar trends between BEAMS, GOSAT, NICAM, and CT2013 in many sub-continental regions. Then, we estimated the terrestrial carbon exchanges in each countries, and could indicated the temporal patterns of the exchanges in large carbon stock regions.Global terrestrial carbon cycle largely depends on a spatial pattern of land cover type, which is heterogeneously-distributed over regional and global scales. Many

  12. Variability in the carbon storage of seagrass habitats and its implications for global estimates of blue carbon ecosystem service.

    Directory of Open Access Journals (Sweden)

    Paul S Lavery

    Full Text Available The recent focus on carbon trading has intensified interest in 'Blue Carbon'-carbon sequestered by coastal vegetated ecosystems, particularly seagrasses. Most information on seagrass carbon storage is derived from studies of a single species, Posidonia oceanica, from the Mediterranean Sea. We surveyed 17 Australian seagrass habitats to assess the variability in their sedimentary organic carbon (C org stocks. The habitats encompassed 10 species, in mono-specific or mixed meadows, depositional to exposed habitats and temperate to tropical habitats. There was an 18-fold difference in the Corg stock (1.09-20.14 mg C org cm(-3 for a temperate Posidonia sinuosa and a temperate, estuarine P. australis meadow, respectively. Integrated over the top 25 cm of sediment, this equated to an areal stock of 262-4833 g C org m(-2. For some species, there was an effect of water depth on the C org stocks, with greater stocks in deeper sites; no differences were found among sub-tidal and inter-tidal habitats. The estimated carbon storage in Australian seagrass ecosystems, taking into account inter-habitat variability, was 155 Mt. At a 2014-15 fixed carbon price of A$25.40 t(-1 and an estimated market price of $35 t(-1 in 2020, the C org stock in the top 25 cm of seagrass habitats has a potential value of $AUD 3.9-5.4 bill. The estimates of annual C org accumulation by Australian seagrasses ranged from 0.093 to 6.15 Mt, with a most probable estimate of 0.93 Mt y(-1 (10.1 t. km(-2 y(-1. These estimates, while large, were one-third of those that would be calculated if inter-habitat variability in carbon stocks were not taken into account. We conclude that there is an urgent need for more information on the variability in seagrass carbon stock and accumulation rates, and the factors driving this variability, in order to improve global estimates of seagrass Blue Carbon storage.

  13. Organic carbon sedimentation rates in Asian mangrove coastal ecosystems estimated by 210PB chronology

    International Nuclear Information System (INIS)

    Tateda, Y.; Wattayakorn, G.; Nhan, D.D.; Kasuya, Y.

    2004-01-01

    Organic carbon balance estimation of mangrove coastal ecosystem is important for understanding of Asian coastal carbon budget/flux calculation in global carbon cycle modelling which is powerful tool for the prediction of future greenhouse gas effect and evaluation of countermeasure preference. Especially, the organic carbon accumulation rate in mangrove ecosystem was reported to be important sink of carbon as well as that in boreal peat accumulation. For the estimation of 10 3 years scale organic carbon accumulation rates in mangrove coastal ecosystems, 14 C was used as long term chronological tracer, being useful in pristine mangrove forest reserve area. While in case of mangrove plantation of in coastal area, the 210 Pb is suitable for the estimation of decades scale estimation by its half-life. Though it has possibility of bio-/physical- turbation effect in applying 210 Pb chronology that is offset in case of 10 3 years scale estimation, especially in Asian mangrove ecosystem where the anthropogenic physical turbation by coastal fishery is vigorous.In this paper, we studied the organic carbon and 210 Pb accumulation rates in subtropical mangrove coastal ecosystems in Japan, Vietnam and Thailand with 7 Be analyses to make sure the negligible effect of above turbation effects on organic carbon accumulation. We finally concluded that 210 Pb was applicable to estimate organic carbon accumulation rates in these ecosystems even though the physical-/bio-turbation is expected. The measured organic carbon accumulation rates using 210 Pb in mangrove coastal ecosystems of Japan, Vietnam and Thailand were 0.067 4.0 t-C ha -1 y -1 . (author)

  14. Estimation and mapping of above ground biomass and carbon of ...

    African Journals Online (AJOL)

    USER

    1Department of Geomatics and Land Management, Makerere University, P.O. Box 7062 ... Biomass is an important parameter for bioenergy modelling, food security, ... –Kyoto climate change agreement on reducing emissions from deforestation and ... the nature of terrain can also affect the amounts of biomass and carbon ...

  15. A model for estimating windbreak carbon within COMET-Farm™

    Science.gov (United States)

    Justin ​Ziegler; Mark Easter; Amy Swan; James Brandle; William Ballesteros; Grant Domke; Adam Chambers; Marlen Eve; Keith. Paustian

    2016-01-01

    Agroforestry as a land management practice presents a method for partially offsetting greenhouse gas emissions from agricultural land. Of all agroforestry practices in the United States, windbreaks in particular are used throughout the United States providing a useful starting point for deriving a modelling systemwhich could quantify the amount of carbon sequestered on...

  16. Estimating Large Area Forest Carbon Stocks—A Pragmatic Design Based Strategy

    Directory of Open Access Journals (Sweden)

    Andrew Haywood

    2017-03-01

    Full Text Available Reducing uncertainty in forest carbon estimates at local and regional scales has become increasingly important due to the centrality of the terrestrial carbon cycle in issues of climate change. In Victoria, Australia, public natural forests extend over 7.2 M ha and constitute a significant and important carbon stock. Recently, a wide range of approaches to estimate carbon stocks within these forests have been developed and applied. However, there are a number of data and estimation limitations associated with these studies. In response, over the last five years, the State of Victoria has implemented a pragmatic plot-based design consisting of pre-stratified permanent observational units located on a state-wide grid. Using the ground sampling grid, we estimated aboveground and belowground carbon stocks (including soil to 0.3 m depth in both National Parks and State Forests, across a wide range of bioregions. Estimates of carbon stocks and associated uncertainty were conducted using simple design based estimators. We detected significantly more carbon in total aboveground and belowground components in State Forests (408.9 t ha−1, 95% confidence interval 388.8–428.9 t ha−1 than National Parks (267.6 t ha−1, 251.9–283.3 t ha−1. We were also able to estimate forest carbon stocks (and associated uncertainty for 21 strata that represent all of Victoria’s bioregions and public tenures. It is anticipated that the lessons learnt from this study may support the discussion on planning and implementing low cost large area forest carbon stock sampling in other jurisdictions.

  17. Specification analysis of plutonium fuels for non-metallic impurities. I. Estimation of carbon

    Energy Technology Data Exchange (ETDEWEB)

    Rizvi, G H; Sethuraman, P R; Venkataramana, P; Natarajan, P R

    1975-01-01

    An analytical method for the estimation of carbon in plutonium samples in the range of 10-400 ..mu..g by conductometry has been developed. In the first step of the method, the entire carbon in sample is converted into CO/sub 2/ which in the second step is completely absorbed in barium hydroxide solution in conductivity of the solution.

  18. Estimating diesel fuel consumption and carbon dioxide emissions from forest road construction

    Science.gov (United States)

    Dan Loeffler; Greg Jones; Nikolaus Vonessen; Sean Healey; Woodam Chung

    2009-01-01

    Forest access road construction is a necessary component of many on-the-ground forest vegetation treatment projects. However, the fuel energy requirements and associated carbon dioxide emissions from forest road construction are unknown. We present a method for estimating diesel fuel consumed and related carbon dioxide emissions from constructing forest roads using...

  19. Specification analysis of plutonium fuels for non-metallic impurities. I - estimation of carbon

    International Nuclear Information System (INIS)

    Rizvi, G.H.; Sethuraman, P.R.; Venkataramana, P.; Natarajan, P.R.

    1975-01-01

    An analytical method for the estimation of carbon in plutonium samples in the range of 10-400 μg by conductometry has been developed. In the first step of the method, the entire carbon in sample is converted into CO 2 which in the second step is completely absorbed in barium hydroxide solution in conductivity of the solution. (M.G.B.)

  20. Markedly divergent estimates of Amazon forest carbon density from ground plots and satellites

    NARCIS (Netherlands)

    Mitchard, Edward T. A.; Feldpausch, Ted R.; Brienen, Roel J. W.; Lopez-Gonzalez, Gabriela; Monteagudo, Abel; Baker, Timothy R.; Lewis, Simon L.; Lloyd, Jon; Quesada, Carlos A.; Gloor, Manuel; ter Steege, Hans|info:eu-repo/dai/nl/075217120; Meir, Patrick; Alvarez, Esteban; Araujo-Murakami, Alejandro; Aragao, Luiz E. O. C.; Arroyo, Luzmila; Aymard, Gerardo; Banki, Olaf; Bonal, Damien; Brown, Sandra; Brown, Foster I.; Ceron, Carlos E.; Chama Moscoso, Victor; Chave, Jerome; Comiskey, James A.; Cornejo, Fernando; Corrales Medina, Massiel; Da Costa, Lola; Costa, Flavia R. C.; Di Fiore, Anthony; Domingues, Tomas F.; Erwin, Terry L.; Frederickson, Todd; Higuchi, Niro; Honorio Coronado, Euridice N.; Levis, Carolina; Killeen, Tim J.; Laurance, William F.; Magnusson, William E.; Marimon, Beatriz S.; Marimon Junior, Ben Hur; Mendoza Polo, Irina; Mishra, Piyush; Nascimento, Marcelo T.; Neill, David; Nunez Vargas, Mario P.; Palacios, Walter A.; Parada, Alexander; Pardo Molina, Guido; Pena-Claros, Marielos; Pitman, Nigel; Peres, Carlos A.; Prieto, Adriana; Poorter, Lourens; Ramirez-Angulo, Hirma; Restrepo Correa, Zorayda; Roopsind, Anand; Roucoux, Katherine H.; Rudas, Agustin; Salomao, Rafael P.; Schietti, Juliana; Silveira, Marcos; de Souza, Priscila F.; Steininger, Marc K.; Stropp, Juliana; Terborgh, John; Thomas, Raquel; Toledo, Marisol; Torres-Lezama, Armando; van Andel, Tinde R.|info:eu-repo/dai/nl/205284868; van der Heijden, Geertje M. F.; Vieira, Ima C. G.; Vieira, Simone; Vilanova-Torre, Emilio; Vos, Vincent A.; Wang, Ophelia; Zartman, Charles E.; Malhi, Yadvinder; Phillips, Oliver L.; Cruz, A.P.; Cuenca, W.P.; Espejo, J.E.; Ferreira, L.; Germaine, A.; Penuela, M.C.; Silva, N.; Valenzuela Gamarra, L.

    Aim The accurate mapping of forest carbon stocks is essential for understanding the global carbon cycle, for assessing emissions from deforestation, and for rational land-use planning. Remote sensing (RS) is currently the key tool for this purpose, but RS does not estimate vegetation biomass

  1. Estimates of live-tree carbon stores in the Pacific Northwest are sensitive to model selection

    Science.gov (United States)

    Susanna L. Melson; Mark E. Harmon; Jeremy S. Fried; James B. Domingo

    2011-01-01

    Estimates of live-tree carbon stores are influenced by numerous uncertainties. One of them is model-selection uncertainty: one has to choose among multiple empirical equations and conversion factors that can be plausibly justified as locally applicable to calculate the carbon store from inventory measurements such as tree height and diameter at breast height (DBH)....

  2. Using basal area to estimate aboveground carbon stocks in forests: La Primavera Biosphere's Reserve, Mexico

    NARCIS (Netherlands)

    Balderas Torres, Arturo; Lovett, Jonathan Cranidge

    2012-01-01

    Increasing use of woody plants for greenhouse gas mitigation has led to demand for rapid, cost-effective estimation of forest carbon stocks. Bole diameter is readily measured and basal area can be correlated to biomass and carbon through application of allometric equations. We explore different

  3. Testing the sensitivity of terrestrial carbon models using remotely sensed biomass estimates

    Science.gov (United States)

    Hashimoto, H.; Saatchi, S. S.; Meyer, V.; Milesi, C.; Wang, W.; Ganguly, S.; Zhang, G.; Nemani, R. R.

    2010-12-01

    There is a large uncertainty in carbon allocation and biomass accumulation in forest ecosystems. With the recent availability of remotely sensed biomass estimates, we now can test some of the hypotheses commonly implemented in various ecosystem models. We used biomass estimates derived by integrating MODIS, GLAS and PALSAR data to verify above-ground biomass estimates simulated by a number of ecosystem models (CASA, BIOME-BGC, BEAMS, LPJ). This study extends the hierarchical framework (Wang et al., 2010) for diagnosing ecosystem models by incorporating independent estimates of biomass for testing and calibrating respiration, carbon allocation, turn-over algorithms or parameters.

  4. Leiurus quinquestriatus venom inhibits BRL 34915-induced 86Rb+ efflux from the rat portal vein

    International Nuclear Information System (INIS)

    Quast, U.; Cook, N.S.

    1988-01-01

    The effect of the crude venom of the Israeli scorpion Leiurus quinquestriatus hebraeus on the 86 Rb + efflux stimulated by the K + channel opener BRL 34915 in the rat portal vein was examined. Applied alone, the venom greatly increased the spontaneous mechanical activity of and the concomitant 86 Rb + efflux from the vessel. When the excitability of the vein was suppressed by the dihydropyridine calcium antagonist, PN 200-110, the 86 Rb + efflux stimulated by BRL 34915 could be shown to be inhibited by the venom. From the concentration dependence of this inhibition an IC 50 value of 0.17 +/- 0.01 mg/ml was estimated. This venom is thus the most potent blocker of BRL 34915-evoked 86 Rb + efflux reported so far. 17 references, 2 figures

  5. Model Effects on GLAS-Based Regional Estimates of Forest Biomass and Carbon

    Science.gov (United States)

    Nelson, Ross

    2008-01-01

    ICESat/GLAS waveform data are used to estimate biomass and carbon on a 1.27 million sq km study area. the Province of Quebec, Canada, below treeline. The same input data sets and sampling design are used in conjunction with four different predictive models to estimate total aboveground dry forest biomass and forest carbon. The four models include nonstratified and stratified versions of a multiple linear model where either biomass or (square root of) biomass serves as the dependent variable. The use of different models in Quebec introduces differences in Provincial biomass estimates of up to 0.35 Gt (range 4.942+/-0.28 Gt to 5.29+/-0.36 Gt). The results suggest that if different predictive models are used to estimate regional carbon stocks in different epochs, e.g., y2005, y2015, one might mistakenly infer an apparent aboveground carbon "change" of, in this case, 0.18 Gt, or approximately 7% of the aboveground carbon in Quebec, due solely to the use of different predictive models. These findings argue for model consistency in future, LiDAR-based carbon monitoring programs. Regional biomass estimates from the four GLAS models are compared to ground estimates derived from an extensive network of 16,814 ground plots located in southern Quebec. Stratified models proved to be more accurate and precise than either of the two nonstratified models tested.

  6. Effects of extracellular pH on UV-induced K+ efflux from cultured rose cells

    International Nuclear Information System (INIS)

    Huerta, A.J.; Murphy, T.M.

    1989-01-01

    Ultraviolet (UV) light causes a specific leakage of K + from cultured rose cells (Rosa damascena). During K + efflux, there is also an increase in extracellular HCO 3 - and acidification of the cell interior. We hypothesized that the HCO 3 - originated from intracellular hydration of respiratory CO 2 and served as a charge balancing mechanism during K + efflux, the K + and HCO 3 - being co transported out of the cell through specific channels. An alternative hypothesis which would yield similar results would be the counter transport of K + and H + . To test these hypotheses, we studied the effect of a range of external pH values (pH 5-9), regulated by various methods (pH-stat, 100 millimolar Tris-Mes buffer, or CO 2 partial pressure), on the UV-induced K + efflux. Both UV-C (less than 290 nanometers) and UV-B (290-310 nanometers) induced K + efflux with a minimum at about pH 6 to 7, and greater efflux at pH values of 5, 8, and 9. Since pH values of 8 and 9 increased instead of reduced the efflux of K + , these data are not consistent with notion that the efflux of K + is dependent on an influx of H + , a process that would be sensitive to external H + concentration. We suggest that the effect of pH on K + efflux may be mediated through the titration of specific K + -transporting proteins or channels in the plasma membrane. Since we could not detect the presence of carbonic anhydrase activity in cell extracts, we could not use the location of this enzyme to aid in our interpretation regarding the site of hydration of CO 2 . (author)

  7. Efflux of inorganic substances from young barley roots. I. Efflux in water culture under various conditions

    Energy Technology Data Exchange (ETDEWEB)

    Fujimoto, H; Kojima, S [Radiation Center of Osaka Prefecture, Sakai (Japan)

    1977-09-01

    The efflux of elements from the roots of hydropomically grown young barley plants was studied. The effects of different mutrient compositions and pH values of the solutions was also studied using /sup 22/Na and /sup 45/Ca as the indexes. In all culture conditions, there was efflux of both elements. In two media with dilute hydrochloric acid and AlCl/sub 3/, respectively, the tendencies of Na and Ca efflux were similar in both media at first, but after 72 hr, the Na efflux in AlCl/sub 3/ decreased and that in dilute hydrochloric acid medium increased. The Ca efflux was high in AlCl/sub 3/ medium,however. The efflux of both Na and Ca was higher in the standard medium than in the media with some bases of high concentrations.

  8. Interpretation and evaluation of combined measurement techniques for soil CO2 efflux: Discrete surface chambers and continuous soil CO2 concentration probes

    Science.gov (United States)

    Diego A. Riveros-Iregui; Brian L. McGlynn; Howard E. Epstein; Daniel L. Welsch

    2008-01-01

    Soil CO2 efflux is a large respiratory flux from terrestrial ecosystems and a critical component of the global carbon (C) cycle. Lack of process understanding of the spatiotemporal controls on soil CO2 efflux limits our ability to extrapolate from fluxes measured at point scales to scales useful for corroboration with other ecosystem level measures of C exchange....

  9. Optimized efflux assay for the NorA multidrug efflux pump in Staphylococcus aureus.

    Science.gov (United States)

    Zimmermann, Saskia; Tuchscherr, Lorena; Rödel, Jürgen; Löffler, Bettina; Bohnert, Jürgen A

    2017-11-01

    Real-time fluorescent efflux assays are commonly used for measuring the efflux of bacterial pumps. Here we describe an optimized protocol for the NorA efflux pump in S. aureus using DiOC 3 instead of ethidium bromide. Glucose and sodium formate were tested as energy carriers. This novel method is fast and reproducible. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. [Remote sensing estimation of urban forest carbon stocks based on QuickBird images].

    Science.gov (United States)

    Xu, Li-Hua; Zhang, Jie-Cun; Huang, Bo; Wang, Huan-Huan; Yue, Wen-Ze

    2014-10-01

    Urban forest is one of the positive factors that increase urban carbon sequestration, which makes great contribution to the global carbon cycle. Based on the high spatial resolution imagery of QuickBird in the study area within the ring road in Yiwu, Zhejiang, the forests in the area were divided into four types, i. e., park-forest, shelter-forest, company-forest and others. With the carbon stock from sample plot as dependent variable, at the significance level of 0.01, the stepwise linear regression method was used to select independent variables from 50 factors such as band grayscale values, vegetation index, texture information and so on. Finally, the remote sensing based forest carbon stock estimation models for the four types of forest were established. The estimation accuracies for all the models were around 70%, with the total carbon reserve of each forest type in the area being estimated as 3623. 80, 5245.78, 5284.84, 5343.65 t, respectively. From the carbon density map, it was found that the carbon reserves were mainly in the range of 25-35 t · hm(-2). In the future, urban forest planners could further improve the ability of forest carbon sequestration through afforestation and interplanting of trees and low shrubs.

  11. Efflux Pump‑Mediated Resistance in Chemotherapy

    African Journals Online (AJOL)

    to elucidate their structure and mechanisms of action so as to integrate the efflux pump mechanisms in the ... resistance. c. Alteration of the penicillin binding protein (PBP) in ..... Perloff MD, von Moltke LL, Fahey JM, Daily JP, Greenblat. DJ.

  12. A new look at ocean carbon remineralization for estimating deepwater sequestration

    DEFF Research Database (Denmark)

    Guidi, L.; Legendre, L.; Reygondeau, Gabriel

    2015-01-01

    provinces, where these estimates range between -50 and +100% of the commonly used globally uniform remineralization value. We apply the regionalized values to satellite-derived estimates of upper ocean POC export to calculate regionalized and ocean-wide deep carbon fluxes and sequestration. The resulting....... These results stress that variable remineralization and sequestration depth should be used to model ocean carbon sequestration and feedback on the atmosphere......The "biological carbon pump" causes carbon sequestration in deep waters by downward transfer of organic matter, mostly as particles. This mechanism depends to a great extent on the uptake of CO2 by marine plankton in surface waters and subsequent sinking of particulate organic carbon (POC) through...

  13. A new estimate of carbon for Bangladesh forest ecosystems with their spatial distribution and REDD+ implications

    DEFF Research Database (Denmark)

    Mukul, Sharif A.; Biswas, Shekhar R.; Rashid, A. Z. M. Manzoor

    2014-01-01

    In tropical developing countries, reducing emissions from deforestation and forest degradation (REDD+) is becoming an important mechanism for conserving forests and protecting biodiversity. A key prerequisite for any successful REDD+ project, however, is obtaining baseline estimates of carbon...... in forest ecosystems. Using available published data, we provide here a new and more reliable estimate of carbon in Bangladesh forest ecosystems, along with their geo-spatial distribution. Our study reveals great variability in carbon density in different forests and higher carbon stock in the mangrove...... ecosystems, followed by in hill forests and in inland Sal (Shorea robusta) forests in the country. Due to its coverage, degraded nature, and diverse stakeholder engagement, the hill forests of Bangladesh can be used to obtain maximum REDD+ benefits. Further research on carbon and biodiversity in under...

  14. Estimation of carbon fibre composites as ITER divertor armour

    Science.gov (United States)

    Pestchanyi, S.; Safronov, V.; Landman, I.

    2004-08-01

    Exposure of the carbon fibre composites (CFC) NB31 and NS31 by multiple plasma pulses has been performed at the plasma guns MK-200UG and QSPA. Numerical simulation for the same CFCs under ITER type I ELM typical heat load has been carried out using the code PEGASUS-3D. Comparative analysis of the numerical and experimental results allowed understanding the erosion mechanism of CFC based on the simulation results. A modification of CFC structure has been proposed in order to decrease the armour erosion rate.

  15. Estimation of carbon fibre composites as ITER divertor armour

    International Nuclear Information System (INIS)

    Pestchanyi, S.; Safronov, V.; Landman, I.

    2004-01-01

    Exposure of the carbon fibre composites (CFC) NB31 and NS31 by multiple plasma pulses has been performed at the plasma guns MK-200UG and QSPA. Numerical simulation for the same CFCs under ITER type I ELM typical heat load has been carried out using the code PEGASUS-3D. Comparative analysis of the numerical and experimental results allowed understanding the erosion mechanism of CFC based on the simulation results. A modification of CFC structure has been proposed in order to decrease the armour erosion rate

  16. Energetics of sodium efflux from Escherichia coli

    International Nuclear Information System (INIS)

    Borbolla, M.G.; Rosen, B.P.

    1984-01-01

    When energy-starved cells of Escherichia coli were passively loaded with 22 Na+, efflux of sodium could be initiated by addition of a source of metabolic energy. Conditions were established where the source of energy was phosphate bond energy, an electrochemical proton gradient, or both. Only an electrochemical proton gradient was required for efflux from intact cells. These results are consistent with secondary exchange of Na+ for H+ catalyzed by a sodium/proton antiporter

  17. Estimates of Forest Biomass Carbon Storage in Liaoning Province of Northeast China: A Review and Assessment

    Science.gov (United States)

    Yu, Dapao; Wang, Xiaoyu; Yin, You; Zhan, Jinyu; Lewis, Bernard J.; Tian, Jie; Bao, Ye; Zhou, Wangming; Zhou, Li; Dai, Limin

    2014-01-01

    Accurate estimates of forest carbon storage and changes in storage capacity are critical for scientific assessment of the effects of forest management on the role of forests as carbon sinks. Up to now, several studies reported forest biomass carbon (FBC) in Liaoning Province based on data from China's Continuous Forest Inventory, however, their accuracy were still not known. This study compared estimates of FBC in Liaoning Province derived from different methods. We found substantial variation in estimates of FBC storage for young and middle-age forests. For provincial forests with high proportions in these age classes, the continuous biomass expansion factor method (CBM) by forest type with age class is more accurate and therefore more appropriate for estimating forest biomass. Based on the above approach designed for this study, forests in Liaoning Province were found to be a carbon sink, with carbon stocks increasing from 63.0 TgC in 1980 to 120.9 TgC in 2010, reflecting an annual increase of 1.9 TgC. The average carbon density of forest biomass in the province has increased from 26.2 Mg ha−1 in 1980 to 31.0 Mg ha−1 in 2010. While the largest FBC occurred in middle-age forests, the average carbon density decreased in this age class during these three decades. The increase in forest carbon density resulted primarily from the increased area and carbon storage of mature forests. The relatively long age interval in each age class for slow-growing forest types increased the uncertainty of FBC estimates by CBM-forest type with age class, and further studies should devote more attention to the time span of age classes in establishing biomass expansion factors for use in CBM calculations. PMID:24586881

  18. Estimating global "blue carbon" emissions from conversion and degradation of vegetated coastal ecosystems.

    Directory of Open Access Journals (Sweden)

    Linwood Pendleton

    Full Text Available Recent attention has focused on the high rates of annual carbon sequestration in vegetated coastal ecosystems--marshes, mangroves, and seagrasses--that may be lost with habitat destruction ('conversion'. Relatively unappreciated, however, is that conversion of these coastal ecosystems also impacts very large pools of previously-sequestered carbon. Residing mostly in sediments, this 'blue carbon' can be released to the atmosphere when these ecosystems are converted or degraded. Here we provide the first global estimates of this impact and evaluate its economic implications. Combining the best available data on global area, land-use conversion rates, and near-surface carbon stocks in each of the three ecosystems, using an uncertainty-propagation approach, we estimate that 0.15-1.02 Pg (billion tons of carbon dioxide are being released annually, several times higher than previous estimates that account only for lost sequestration. These emissions are equivalent to 3-19% of those from deforestation globally, and result in economic damages of $US 6-42 billion annually. The largest sources of uncertainty in these estimates stems from limited certitude in global area and rates of land-use conversion, but research is also needed on the fates of ecosystem carbon upon conversion. Currently, carbon emissions from the conversion of vegetated coastal ecosystems are not included in emissions accounting or carbon market protocols, but this analysis suggests they may be disproportionally important to both. Although the relevant science supporting these initial estimates will need to be refined in coming years, it is clear that policies encouraging the sustainable management of coastal ecosystems could significantly reduce carbon emissions from the land-use sector, in addition to sustaining the well-recognized ecosystem services of coastal habitats.

  19. Comparison of methods for estimating carbon dioxide storage by Sacramento's urban forest

    Science.gov (United States)

    Elena Aguaron; E. Gregory McPherson

    2012-01-01

    Limited open-grown urban tree species biomass equations have necessitated use of forest-derived equations with diverse conclusions on the accuracy of these equations to estimate urban biomass and carbon storage. Our goal was to determine and explain variability among estimates of CO2 storage from four sets of allometric equations for the same...

  20. Equivalence among three alternative approaches to estimating live tree carbon stocks in the eastern United States

    Science.gov (United States)

    Coeli M. Hoover; James E. Smith

    2017-01-01

    Assessments of forest carbon are available via multiple alternate tools or applications and are in use to address various regulatory and reporting requirements. The various approaches to making such estimates may or may not be entirely comparable. Knowing how the estimates produced by some commonly used approaches vary across forest types and regions allows users of...

  1. Inventory-based estimates of forest biomass carbon stocks in China: A comparison of three methods

    Science.gov (United States)

    Zhaodi Guo; Jingyun Fang; Yude Pan; Richard. Birdsey

    2010-01-01

    Several studies have reported different estimates for forest biomass carbon (C) stocks in China. The discrepancy among these estimates may be largely attributed to the methods used. In this study, we used three methods [mean biomass density method (MBM), mean ratio method (MRM), and continuous biomass expansion factor (BEF) method (abbreviated as CBM)] applied to...

  2. Estimating national forest carbon stocks and dynamics: combining models and remotely sensed information

    Science.gov (United States)

    Smallman, Thomas Luke; Exbrayat, Jean-François; Bloom, Anthony; Williams, Mathew

    2017-04-01

    Forests are a critical component of the global carbon cycle, storing significant amounts of carbon, split between living biomass and dead organic matter. The carbon budget of forests is the most uncertain component of the global carbon cycle - it is currently impossible to quantify accurately the carbon source/sink strength of forest biomes due to their heterogeneity and complex dynamics. It has been a major challenge to generate robust carbon budgets across landscapes due to data scarcity. Models have been used for estimating carbon budgets, but outputs have lacked an assessment of uncertainty, making a robust assessment of their reliability and accuracy challenging. Here a Metropolis Hastings - Markov Chain Monte Carlo (MH-MCMC) data assimilation framework has been used to combine remotely sensed leaf area index (MODIS), biomass (where available) and deforestation estimates, in addition to forest planting information from the UK's national forest inventory, an estimate of soil carbon from the Harmonized World Database (HWSD) and plant trait information with a process model (DALEC) to produce a constrained analysis with a robust estimate of uncertainty of the UK forestry carbon budget between 2000 and 2010. Our analysis estimates the mean annual UK forest carbon sink at -3.9 MgC ha-1 yr-1 with a 95 % confidence interval between -4.0 and -3.1 MgC ha-1yr-1. The UK national forest inventory (NFI) estimates the mean UK forest carbon sink to be between -1.4 and -5.5 MgC ha-1 yr-1. The analysis estimate for total forest biomass stock in 2010 is estimated at 229 (177/232) TgC, while the NFI an estimated total forest biomass carbon stock of 216 TgC. Leaf carbon area (LCA) is a key plant trait which we are able to estimate using our analysis. Comparison of median estimates for (LCA) retrieved from the analysis and a UK land cover map show higher and lower values for LCA are estimated areas dominated by needle leaf and broad leaf forests forest respectively, consistent with

  3. Estimation of the global climate effect of brown carbon

    Science.gov (United States)

    Zhang, A.; Wang, Y.; Zhang, Y.; Weber, R. J.; Song, Y.

    2017-12-01

    Carbonaceous aerosols significantly affect global radiative forcing and climate through absorption and scattering of sunlight. Black carbon (BC) and brown carbon (BrC) are light-absorbing carbonaceous aerosols. The global distribution and climate effect of BrC is uncertain. A recent study suggests that BrC absorption is comparable to BC in the upper troposphere over biomass burning region and that the resulting heating tends to stabilize the atmosphere. Yet current climate models do not include proper treatments of BrC. In this study, we derived a BrC global biomass burning emission inventory from Global Fire Emissions Database 4 (GFED4) and developed a BrC module in the Community Atmosphere Model version 5 (CAM5) of Community Earth System Model (CESM) model. The model simulations compared well to BrC observations of the Studies of Emissions, Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) and Deep Convective Clouds and Chemistry Project (DC-3) campaigns and includes BrC bleaching. Model results suggested that BrC in the upper troposphere due to convective transport is as important an absorber as BC globally. Upper tropospheric BrC radiative forcing is particularly significant over the tropics, affecting the atmosphere stability and Hadley circulation.

  4. [Estimation of soil carbon sequestration potential in typical steppe of Inner Mongolia and associated uncertainty].

    Science.gov (United States)

    Wang, Wei; Wu, Jian-Guo; Han, Xing-Guo

    2012-01-01

    Based on the measurements in the enclosure and uncontrolled grazing plots in the typical steppe of Xilinguole, Inner Mongolia, this paper studied the soil carbon storage and carbon sequestration in the grasslands dominated by Leymus chinensis, Stipa grandis, and Stipa krylovii, respectively, and estimated the regional scale soil carbon sequestration potential in the heavily degraded grassland after restoration. At local scale, the annual soil carbon sequestration in the three grasslands all decreased with increasing year of enclosure. The soil organic carbon storage was significantly higher in the grasslands dominated by L. chinensis and Stipa grandis than in that dominated by Stipa krylovii, but the latter had much higher soil carbon sequestration potential, because of the greater loss of soil organic carbon during the degradation process due to overgrazing. At regional scale, the soil carbon sequestration potential at the depth of 0-20 cm varied from -0.03 x 10(4) to 3.71 x 10(4) kg C x a(-1), and the total carbon sequestration potential was 12.1 x 10(8) kg C x a(-1). Uncertainty analysis indicated that soil gravel content had less effect on the estimated carbon sequestration potential, but the estimation errors resulted from the spatial interpolation of climate data could be about +/- 4.7 x 10(9) kg C x a(-1). In the future, if the growth season precipitation in this region had an average variation of -3.2 mm x (10 a)(-1), the soil carbon sequestration potential would be de- creased by 1.07 x 10(8) kg C x (10 a)(-1).

  5. Fatigue Life Estimation of Medium-Carbon Steel with Different Surface Roughness

    Directory of Open Access Journals (Sweden)

    Changyou Li

    2017-03-01

    Full Text Available Medium-carbon steel is commonly used for the rail, wire ropes, tire cord, cold heading, forging steels, cold finished steel bars, machinable steel and so on. Its fatigue behavior analysis and fatigue life estimation play an important role in the machinery industry. In this paper, the estimation of fatigue life of medium-carbon steel with different surface roughness using established S-N and P-S-N curves is presented. To estimate the fatigue life, the effect of the average surface roughness on the fatigue life of medium-carbon steel has been investigated using 75 fatigue tests in three groups with average surface roughness (Ra: 0.4 μm, 0.8 μm, and 1.6 μm, respectively. S-N curves and P-S-N curves have been established based on the fatigue tests. The fatigue life of medium-carbon steel is then estimated based on Tanaka-Mura crack initiation life model, the crack propagation life model using Paris law, and material constants of the S-N curves. Six more fatigue tests have been conducted to validate the presented fatigue life estimation formulation. The experimental results have shown that the presented model could estimate well the mean fatigue life of medium-carbon steel with different surface roughness.

  6. Estimating the National Carbon Abatement Potential of City Policies: A Data- Driven Approach

    Energy Technology Data Exchange (ETDEWEB)

    Eric O’Shaughnessy, Jenny Heeter, David Keyser, Pieter Gagnon, and Alexandra Aznar

    2016-10-01

    Cities are increasingly taking actions such as building code enforcement, urban planning, and public transit expansion to reduce emissions of carbon dioxide in their communities and municipal operations. However, many cities lack the quantitative information needed to estimate policy impacts and prioritize city actions in terms of carbon abatement potential and cost effectiveness. This report fills this research gap by providing methodologies to assess the carbon abatement potential of a variety of city actions. The methodologies are applied to an energy use data set of 23,458 cities compiled for the U.S. Department of Energy’s City Energy Profile tool. The analysis estimates the national carbon abatement potential of the most commonly implemented actions in six specific policy areas. The results of this analysis suggest that, in aggregate, cities could reduce nationwide carbon emissions by about 210 million metric tons of carbon dioxide (MMT CO2) per year in a "moderate abatement scenario" by 2035 and 480 MMT CO2/year in a "high abatement scenario" by 2035 through these common actions typically within a city’s control in the six policy areas. The aggregate carbon abatement potential of these specific areas equates to a reduction of 3%-7% relative to 2013 U.S. emissions. At the city level, the results suggest the average city could reduce carbon emissions by 7% (moderate) to 19% (high) relative to current city-level emissions. City carbon abatement potential is sensitive to national and state policies that affect the carbon intensity of electricity and transportation. Specifically, the U.S. Clean Power Plan and further renewable energy cost reductions could reduce city carbon emissions overall, helping cities achieve their carbon reduction goals.

  7. Quantitative Estimation of the Climatic Effects of Carbon Transferred by International Trade.

    Science.gov (United States)

    Wei, Ting; Dong, Wenjie; Moore, John; Yan, Qing; Song, Yi; Yang, Zhiyong; Yuan, Wenping; Chou, Jieming; Cui, Xuefeng; Yan, Xiaodong; Wei, Zhigang; Guo, Yan; Yang, Shili; Tian, Di; Lin, Pengfei; Yang, Song; Wen, Zhiping; Lin, Hui; Chen, Min; Feng, Guolin; Jiang, Yundi; Zhu, Xian; Chen, Juan; Wei, Xin; Shi, Wen; Zhang, Zhiguo; Dong, Juan; Li, Yexin; Chen, Deliang

    2016-06-22

    Carbon transfer via international trade affects the spatial pattern of global carbon emissions by redistributing emissions related to production of goods and services. It has potential impacts on attribution of the responsibility of various countries for climate change and formulation of carbon-reduction policies. However, the effect of carbon transfer on climate change has not been quantified. Here, we present a quantitative estimate of climatic impacts of carbon transfer based on a simple CO2 Impulse Response Function and three Earth System Models. The results suggest that carbon transfer leads to a migration of CO2 by 0.1-3.9 ppm or 3-9% of the rise in the global atmospheric concentrations from developed countries to developing countries during 1990-2005 and potentially reduces the effectiveness of the Kyoto Protocol by up to 5.3%. However, the induced atmospheric CO2 concentration and climate changes (e.g., in temperature, ocean heat content, and sea-ice) are very small and lie within observed interannual variability. Given continuous growth of transferred carbon emissions and their proportion in global total carbon emissions, the climatic effect of traded carbon is likely to become more significant in the future, highlighting the need to consider carbon transfer in future climate negotiations.

  8. Quantitative Estimation of the Climatic Effects of Carbon Transferred by International Trade

    Science.gov (United States)

    Wei, Ting; Dong, Wenjie; Moore, John; Yan, Qing; Song, Yi; Yang, Zhiyong; Yuan, Wenping; Chou, Jieming; Cui, Xuefeng; Yan, Xiaodong; Wei, Zhigang; Guo, Yan; Yang, Shili; Tian, Di; Lin, Pengfei; Yang, Song; Wen, Zhiping; Lin, Hui; Chen, Min; Feng, Guolin; Jiang, Yundi; Zhu, Xian; Chen, Juan; Wei, Xin; Shi, Wen; Zhang, Zhiguo; Dong, Juan; Li, Yexin; Chen, Deliang

    2016-06-01

    Carbon transfer via international trade affects the spatial pattern of global carbon emissions by redistributing emissions related to production of goods and services. It has potential impacts on attribution of the responsibility of various countries for climate change and formulation of carbon-reduction policies. However, the effect of carbon transfer on climate change has not been quantified. Here, we present a quantitative estimate of climatic impacts of carbon transfer based on a simple CO2 Impulse Response Function and three Earth System Models. The results suggest that carbon transfer leads to a migration of CO2 by 0.1-3.9 ppm or 3-9% of the rise in the global atmospheric concentrations from developed countries to developing countries during 1990-2005 and potentially reduces the effectiveness of the Kyoto Protocol by up to 5.3%. However, the induced atmospheric CO2 concentration and climate changes (e.g., in temperature, ocean heat content, and sea-ice) are very small and lie within observed interannual variability. Given continuous growth of transferred carbon emissions and their proportion in global total carbon emissions, the climatic effect of traded carbon is likely to become more significant in the future, highlighting the need to consider carbon transfer in future climate negotiations.

  9. Potential for using remote sensing to estimate carbon fluxes across northern peatlands - A review.

    Science.gov (United States)

    Lees, K J; Quaife, T; Artz, R R E; Khomik, M; Clark, J M

    2018-02-15

    Peatlands store large amounts of terrestrial carbon and any changes to their carbon balance could cause large changes in the greenhouse gas (GHG) balance of the Earth's atmosphere. There is still much uncertainty about how the GHG dynamics of peatlands are affected by climate and land use change. Current field-based methods of estimating annual carbon exchange between peatlands and the atmosphere include flux chambers and eddy covariance towers. However, remote sensing has several advantages over these traditional approaches in terms of cost, spatial coverage and accessibility to remote locations. In this paper, we outline the basic principles of using remote sensing to estimate ecosystem carbon fluxes and explain the range of satellite data available for such estimations, considering the indices and models developed to make use of the data. Past studies, which have used remote sensing data in comparison with ground-based calculations of carbon fluxes over Northern peatland landscapes, are discussed, as well as the challenges of working with remote sensing on peatlands. Finally, we suggest areas in need of future work on this topic. We conclude that the application of remote sensing to models of carbon fluxes is a viable research method over Northern peatlands but further work is needed to develop more comprehensive carbon cycle models and to improve the long-term reliability of models, particularly on peatland sites undergoing restoration. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  10. Genotype and plant trait effects on soil CO2 efflux responses to altered precipitation in switchgrass

    Science.gov (United States)

    Background/Question/Methods Global climate change models predict increasing drought during the growing season, which will alter many ecosystem processes including soil CO2 efflux (JCO2), with potential consequences for carbon retention in soils. Soil moisture, soil temperature and plant traits such...

  11. Effect of soil compaction and biomass removal on soil CO2 efflux in a Missouri forest

    Science.gov (United States)

    Felix, Jr. Ponder

    2005-01-01

    Forest disturbances associated with harvesting activities can affect soil properties and soil respiration. A soda-lime technique was used to measure soil carbon dioxide (CO2) efflux rates in clearcut plots of a Missouri oak-hickory (Quercus spp. L.-Carya spp. Nutt.) forest 4 years after being treated with two levels of forest...

  12. Estimation of Global 1km-grid Terrestrial Carbon Exchange Part I: Developing Inputs and Modelling

    Science.gov (United States)

    Sasai, T.; Murakami, K.; Kato, S.; Matsunaga, T.; Saigusa, N.; Hiraki, K.

    2015-12-01

    Global terrestrial carbon cycle largely depends on a spatial pattern in land cover type, which is heterogeneously-distributed over regional and global scales. However, most studies, which aimed at the estimation of carbon exchanges between ecosystem and atmosphere, remained within several tens of kilometers grid spatial resolution, and the results have not been enough to understand the detailed pattern of carbon exchanges based on ecological community. Improving the sophistication of spatial resolution is obviously necessary to enhance the accuracy of carbon exchanges. Moreover, the improvement may contribute to global warming awareness, policy makers and other social activities. In this study, we show global terrestrial carbon exchanges (net ecosystem production, net primary production, and gross primary production) with 1km-grid resolution. As methodology for computing the exchanges, we 1) developed a global 1km-grid climate and satellite dataset based on the approach in Setoyama and Sasai (2013); 2) used the satellite-driven biosphere model (Biosphere model integrating Eco-physiological And Mechanistic approaches using Satellite data: BEAMS) (Sasai et al., 2005, 2007, 2011); 3) simulated the carbon exchanges by using the new dataset and BEAMS by the use of a supercomputer that includes 1280 CPU and 320 GPGPU cores (GOSAT RCF of NIES). As a result, we could develop a global uniform system for realistically estimating terrestrial carbon exchange, and evaluate net ecosystem production in each community level; leading to obtain highly detailed understanding of terrestrial carbon exchanges.

  13. Lidar-derived estimate and uncertainty of carbon sink in successional phases of woody encroachment

    Science.gov (United States)

    Sankey, Temuulen; Shrestha, Rupesh; Sankey, Joel B.; Hardegree, Stuart; Strand, Eva

    2013-07-01

    encroachment is a globally occurring phenomenon that contributes to the global carbon sink. The magnitude of this contribution needs to be estimated at regional and local scales to address uncertainties present in the global- and continental-scale estimates, and guide regional policy and management in balancing restoration activities, including removal of woody plants, with greenhouse gas mitigation goals. The objective of this study was to estimate carbon stored in various successional phases of woody encroachment. Using lidar measurements of individual trees, we present high-resolution estimates of aboveground carbon storage in juniper woodlands. Segmentation analysis of lidar point cloud data identified a total of 60,628 juniper tree crowns across four watersheds. Tree heights, canopy cover, and density derived from lidar were strongly correlated with field measurements of 2613 juniper stems measured in 85 plots (30 × 30 m). Aboveground total biomass of individual trees was estimated using a regression model with lidar-derived height and crown area as predictors (Adj. R2 = 0.76, p < 0.001, RMSE = 0.58 kg). The predicted mean aboveground woody carbon storage for the study area was 677 g/m2. Uncertainty in carbon storage estimates was examined with a Monte Carlo approach that addressed major error sources. Ranges predicted with uncertainty analysis in the mean, individual tree, aboveground woody C, and associated standard deviation were 0.35 - 143.6 kg and 0.5 - 1.25 kg, respectively. Later successional phases of woody encroachment had, on average, twice the aboveground carbon relative to earlier phases. Woody encroachment might be more successfully managed and balanced with carbon storage goals by identifying priority areas in earlier phases of encroachment where intensive treatments are most effective.

  14. Determination of the equation parameters of carbon flow curves and estimated carbon flow and CO2 emissions from broiler production.

    Science.gov (United States)

    Henn, J D; Bockor, L; Borille, R; Coldebella, A; Ribeiro, A M L; Kessler, A M

    2015-09-01

    The objective of this study was to determine the equation parameters of carbon (i.e., C) flow curves and to estimate C flow and carbon dioxide (i.e., CO2) emissions from the production of 1- to 49-day-old broilers from different genetic strains. In total, 384 1-day-old chicks were used, distributed into 4 groups: high-performance males (Cobb-M) and females (Cobb-F), and intermediate-performance males (C44-M) and females (C44-F), with 6 replicates/treatment according to a completely randomized study design. Carbon intake and retention were calculated based on diet and body C composition, and expired C was stoichiometrically estimated as digestible C intake-C retention-C in the urine. Litter C emission was estimated as initial litter C+C in the excreta-final litter C. Carbon flow curves were determined fitting data by nonlinear regression using the Gompertz function. Expired CO2 was calculated based on expired C. The applied nonlinear model presented goodness-of-fit for all responses (R2>0.99). Carbon dioxide production was highly correlated with growth rate. At 42 d age, CO2 expiration (g/bird) was 3,384.4 for Cobb-M, 2,947.9 for Cobb-F, 2,512.5 for C44-M, and 2185.1 for C44-F. Age also significantly affected CO2 production: to achieve 2.0 kg BW, CO2 expiration (g/bird) was 1,794.3 for Cobb-M, 2,016.5 for Cobb-F, 2617.7 for C44-M, and 3,092.3 for C44-F. The obtained equations present high predictability to estimate individual CO2 emissions in strains of Cobb and C44 broilers of any weight, or age, reared between 1 and 49 d age. © 2015 Poultry Science Association Inc.

  15. Quantifying the Effects of Historical Land Cover Conversion Uncertainty on Global Carbon and Climate Estimates

    Science.gov (United States)

    Di Vittorio, A. V.; Mao, J.; Shi, X.; Chini, L.; Hurtt, G.; Collins, W. D.

    2018-01-01

    Previous studies have examined land use change as a driver of global change, but the translation of land use change into land cover conversion has been largely unconstrained. Here we quantify the effects of land cover conversion uncertainty on the global carbon and climate system using the integrated Earth System Model. Our experiments use identical land use change data and vary land cover conversions to quantify associated uncertainty in carbon and climate estimates. Land cover conversion uncertainty is large, constitutes a 5 ppmv range in estimated atmospheric CO2 in 2004, and generates carbon uncertainty that is equivalent to 80% of the net effects of CO2 and climate and 124% of the effects of nitrogen deposition during 1850-2004. Additionally, land cover uncertainty generates differences in local surface temperature of over 1°C. We conclude that future studies addressing land use, carbon, and climate need to constrain and reduce land cover conversion uncertainties.

  16. Estimation of Black Carbon Emissions from Dry Dipterocarp Forest Fires in Thailand

    Directory of Open Access Journals (Sweden)

    Ubonwan Chaiyo

    2014-12-01

    Full Text Available This study focused on the estimation of black carbon emissions from dry dipterocarp forest fires in Thailand. Field experiments were set up at the natural forest, Mae Nam Phachi wildlife sanctuary, Ratchaburi Province, Thailand. The dead leaves were the main component consumed of the surface biomass with coverage higher than 90% in volume and mass. The dead leaves load was 342 ± 190 g∙m−2 and followed by a little mass load of twig, 100 g∙m−2. The chemical analysis of the dead leaves showed that the carbon content in the experimental biomass fuel was 45.81 ± 0.04%. From the field experiments, it was found that 88.38 ± 2.02% of the carbon input was converted to carbon released to the atmosphere, while less than 10% were left in the form of residues, and returned to soil. The quantity of dead leaves consumed to produce each gram of carbon released was 2.40 ± 0.02 gdry biomass burned. From the study, the emissions factor of carbon dioxide, carbon monoxide, particulate matter (PM2.5 and black carbon amounted 1329, 90, 26.19 and 2.83 g∙kg−1dry biomass burned, respectively. In Thailand, the amount of black carbon emissions from dry dipterocarp forest fires amounted 17.43 tonnes∙y−1.

  17. Developing mechanisms for estimating carbon footprint in farming systems

    Science.gov (United States)

    Anaya-Romero, María; Fernández Luque, José Enrique; Rodríguez Merino, Alejandro; José Moreno Delgado, Juan; Rodado, Concepción Mira; Romero Vicente, Rafael; Perez-Martin, Alfonso; Muñoz-Rojas, Miriam

    2015-04-01

    Sustainable land management is critical to avoid land degradation and to reclaim degraded land for its productive use and for reaping the benefits of crucial ecosystem services and protecting biodiversity. It also helps in mitigating and adapting to climate change. Land and its various uses are affected severely by climate change too (flooding, droughts, etc.). Existing tools and technologies for efficient land management need to be adapted and their application expanded. A large number of human livelihoods and ecosystems can benefit from these tools and techniques since these yield multiple benefits. Disseminating and scaling up the implementation of sustainable land management approaches will, however, need to be backed up by mobilizing strong political will and financial resources. The challenge is to provide an integral decision support tool that can establish relationships between soil carbon content, climate change and land use and management aspects that allow stakeholders to detect, cope with and intervene into land system change in a sustainable way. In order to achieve this goal an agro-ecological meta-model called CarboLAND will be calibrated in several plots located in Andalusia region, Southern Spain, under different scenarios of climate and agricultural use and management. The output will be the CLIMALAND e-platform, which will also include protocols in order to support stakeholders for an integrated ecosystem approach, taking into account biodiversity, hydrological and soil capability, socio-economic aspects, and regional and environmental policies. This tool will be made available at the European context for a regional level, providing user-friendly interfaces and a scientifically-technical platform for the assessment of sustainable land use and management.

  18. [Estimation of Hunan forest carbon density based on spectral mixture analysis of MODIS data].

    Science.gov (United States)

    Yan, En-ping; Lin, Hui; Wang, Guang-xing; Chen, Zhen-xiong

    2015-11-01

    With the fast development of remote sensing technology, combining forest inventory sample plot data and remotely sensed images has become a widely used method to map forest carbon density. However, the existence of mixed pixels often impedes the improvement of forest carbon density mapping, especially when low spatial resolution images such as MODIS are used. In this study, MODIS images and national forest inventory sample plot data were used to conduct the study of estimation for forest carbon density. Linear spectral mixture analysis with and without constraint, and nonlinear spectral mixture analysis were compared to derive the fractions of different land use and land cover (LULC) types. Then sequential Gaussian co-simulation algorithm with and without the fraction images from spectral mixture analyses were employed to estimate forest carbon density of Hunan Province. Results showed that 1) Linear spectral mixture analysis with constraint, leading to a mean RMSE of 0.002, more accurately estimated the fractions of LULC types than linear spectral and nonlinear spectral mixture analyses; 2) Integrating spectral mixture analysis model and sequential Gaussian co-simulation algorithm increased the estimation accuracy of forest carbon density to 81.5% from 74.1%, and decreased the RMSE to 5.18 from 7.26; and 3) The mean value of forest carbon density for the province was 30.06 t · hm(-2), ranging from 0.00 to 67.35 t · hm(-2). This implied that the spectral mixture analysis provided a great potential to increase the estimation accuracy of forest carbon density on regional and global level.

  19. Using carbon emissions, oxygen consumption, and energy retention estimates to calculate dietary energy partitioning and estimate forage intake by beef steers

    Science.gov (United States)

    Take home Message: Estimating ME intake by grazing cattle seems possible using respiration gas exchange estimates. Introduction: We hypothesized that carbon dioxide, methane, and oxigen exchange estimates in breath clouds could be used as biomarkers to ultimately estimate dry matter intake in grazi...

  20. Lidar-derived estimate and uncertainty of carbon sink in successional phases of woody encroachment

    Science.gov (United States)

    Sankey, Temuulen; Shrestha, Rupesh; Sankey, Joel B.; Hardgree, Stuart; Strand, Eva

    2013-01-01

    Woody encroachment is a globally occurring phenomenon that contributes to the global carbon sink. The magnitude of this contribution needs to be estimated at regional and local scales to address uncertainties present in the global- and continental-scale estimates, and guide regional policy and management in balancing restoration activities, including removal of woody plants, with greenhouse gas mitigation goals. The objective of this study was to estimate carbon stored in various successional phases of woody encroachment. Using lidar measurements of individual trees, we present high-resolution estimates of aboveground carbon storage in juniper woodlands. Segmentation analysis of lidar point cloud data identified a total of 60,628 juniper tree crowns across four watersheds. Tree heights, canopy cover, and density derived from lidar were strongly correlated with field measurements of 2613 juniper stems measured in 85 plots (30 × 30 m). Aboveground total biomass of individual trees was estimated using a regression model with lidar-derived height and crown area as predictors (Adj. R2 = 0.76, p 2. Uncertainty in carbon storage estimates was examined with a Monte Carlo approach that addressed major error sources. Ranges predicted with uncertainty analysis in the mean, individual tree, aboveground woody C, and associated standard deviation were 0.35 – 143.6 kg and 0.5 – 1.25 kg, respectively. Later successional phases of woody encroachment had, on average, twice the aboveground carbon relative to earlier phases. Woody encroachment might be more successfully managed and balanced with carbon storage goals by identifying priority areas in earlier phases of encroachment where intensive treatments are most effective.

  1. Quantitative estimation of carbonation and chloride penetration in reinforced concrete by laser-induced breakdown spectroscopy

    Science.gov (United States)

    Eto, Shuzo; Matsuo, Toyofumi; Matsumura, Takuro; Fujii, Takashi; Tanaka, Masayoshi Y.

    2014-11-01

    The penetration profile of chlorine in a reinforced concrete (RC) specimen was determined by laser-induced breakdown spectroscopy (LIBS). The concrete core was prepared from RC beams with cracking damage induced by bending load and salt water spraying. LIBS was performed using a specimen that was obtained by splitting the concrete core, and the line scan of laser pulses gave the two-dimensional emission intensity profiles of 100 × 80 mm2 within one hour. The two-dimensional profile of the emission intensity suggests that the presence of the crack had less effect on the emission intensity when the measurement interval was larger than the crack width. The chlorine emission spectrum was measured without using the buffer gas, which is usually used for chlorine measurement, by collinear double-pulse LIBS. The apparent diffusion coefficient, which is one of the most important parameters for chloride penetration in concrete, was estimated using the depth profile of chlorine emission intensity and Fick's law. The carbonation depth was estimated on the basis of the relationship between carbon and calcium emission intensities. When the carbon emission intensity was statistically higher than the calcium emission intensity at the measurement point, we determined that the point was carbonated. The estimation results were consistent with the spraying test results using phenolphthalein solution. These results suggest that the quantitative estimation by LIBS of carbonation depth and chloride penetration can be performed simultaneously.

  2. Estimating the National Carbon Abatement Potential of City Policies: A Data-Driven Approach

    Energy Technology Data Exchange (ETDEWEB)

    O' Shaughnessy, Eric [National Renewable Energy Lab. (NREL), Golden, CO (United States); Heeter, Jenny [National Renewable Energy Lab. (NREL), Golden, CO (United States); Keyser, David [National Renewable Energy Lab. (NREL), Golden, CO (United States); Gagnon, Pieter [National Renewable Energy Lab. (NREL), Golden, CO (United States); Aznar, Alexandra [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2016-10-01

    Cities are increasingly taking actions such as building code enforcement, urban planning, and public transit expansion to reduce emissions of carbon dioxide in their communities and municipal operations. However, many cities lack the quantitative information needed to estimate policy impacts and prioritize city actions in terms of carbon abatement potential and cost effectiveness. This report fills this research gap by providing methodologies to assess the carbon abatement potential of a variety of city actions. The methodologies are applied to an energy use data set of 23,458 cities compiled for the U.S. Department of Energy City Energy Profile tool. The analysis develops a national estimate of the carbon abatement potential of realizable city actions in six specific policy areas encompassing the most commonly implemented city actions. The results of this analysis suggest that, in aggregate, cities could reduce nationwide carbon emissions by about 210 million metric tons of carbon dioxide (MMT CO2) per year in a 'moderate abatement scenario' by 2035 and 480 MMT CO2/year in a 'high abatement scenario' by 2035 through these common actions typically within a city's control in the six policy areas. The aggregate carbon abatement potential of these specific areas equates to a reduction of 3%-7% relative to 2013 U.S. emissions. At the city level, the results suggest the average city could reduce carbon emissions by 7% (moderate) to 19% (high) relative to current city-level emissions. In the context of U.S. climate commitments under the 21st session of the Conference of the Parties (COP21), the estimated national abatement potential of the city actions analyzed in this report equates to about 15%-35% of the remaining carbon abatement necessary to achieve the U.S. COP21 target. Additional city actions outside the scope of this report, such as community choice aggregation (city-level purchasing of renewable energy), zero energy districts, and multi

  3. Can current moisture responses predict soil CO2 efflux under altered precipitation regimes? A synthesis of manipulation experiments

    Science.gov (United States)

    S. Vicca; M. Bahn; M. Estiarte; E. E. van Loon; R. Vargas; G. Alberti; P. Ambus; M. A. Arain; C. Beier; L. P. Bentley; W. Borken; N. Buchmann; S. L. Collins; G. de Dato; J. S. Dukes; C. Escolar; P. Fay; G. Guidolotti; P. J. Hanson; A. Kahmen; G. Kröel-Dulay; T. Ladreiter-Knauss; K. S. Larsen; E. Lellei-Kovacs; E. Lebrija-Trejos; F. T. Maestre; S. Marhan; M. Marshall; P. Meir; Y. Miao; J. Muhr; P. A. Niklaus; R. Ogaya; J. Peñuelas; C. Poll; L. E. Rustad; K. Savage; A. Schindlbacher; I. K. Schmidt; A. R. Smith; E. D. Sotta; V. Suseela; A. Tietema; N. van Gestel; O. van Straaten; S. Wan; U. Weber; I. A. Janssens

    2014-01-01

    As a key component of the carbon cycle, soil CO2 efflux (SCE) is being increasingly studied to improve our mechanistic understanding of this important carbon flux. Predicting ecosystem responses to climate change often depends an extrapolation of current relationships between ecosystem processes and their climatic drivers to conditions not yet experienced by the...

  4. Effects of atmospheric CO2 enrichment on soil CO2 efflux in a young longleaf pine system

    Science.gov (United States)

    Elevated atmospheric carbon dioxide (CO2) can affect the quantity and quality of plant tissues which will impact carbon (C) cycling and storage in plant/soil systems and the release of CO2 back to the atmosphere. Research is needed to quantify the effects of elevated CO2 on soil CO2 efflux to predi...

  5. Luminescence imaging of water during carbon-ion irradiation for range estimation

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, Seiichi, E-mail: s-yama@met.nagoya-u.ac.jp; Komori, Masataka; Koyama, Shuji; Morishita, Yuki; Sekihara, Eri [Radiological and Medical Laboratory Sciences, Nagoya University Graduate School of Medicine, Higashi-ku, Nagoya, Aichi 461-8673 (Japan); Akagi, Takashi; Yamashita, Tomohiro [Hygo Ion Beam Medical Center, Hyogo 679-5165 (Japan); Toshito, Toshiyuki [Department of Proton Therapy Physics, Nagoya Proton Therapy Center, Nagoya City West Medical Center, Aichi 462-8508 (Japan)

    2016-05-15

    Purpose: The authors previously reported successful luminescence imaging of water during proton irradiation and its application to range estimation. However, since the feasibility of this approach for carbon-ion irradiation remained unclear, the authors conducted luminescence imaging during carbon-ion irradiation and estimated the ranges. Methods: The authors placed a pure-water phantom on the patient couch of a carbon-ion therapy system and measured the luminescence images with a high-sensitivity, cooled charge-coupled device camera during carbon-ion irradiation. The authors also carried out imaging of three types of phantoms (tap-water, an acrylic block, and a plastic scintillator) and compared their intensities and distributions with those of a phantom containing pure-water. Results: The luminescence images of pure-water phantoms during carbon-ion irradiation showed clear Bragg peaks, and the measured carbon-ion ranges from the images were almost the same as those obtained by simulation. The image of the tap-water phantom showed almost the same distribution as that of the pure-water phantom. The acrylic block phantom’s luminescence image produced seven times higher luminescence and had a 13% shorter range than that of the water phantoms; the range with the acrylic phantom generally matched the calculated value. The plastic scintillator showed ∼15 000 times higher light than that of water. Conclusions: Luminescence imaging during carbon-ion irradiation of water is not only possible but also a promising method for range estimation in carbon-ion therapy.

  6. Luminescence imaging of water during carbon-ion irradiation for range estimation

    International Nuclear Information System (INIS)

    Yamamoto, Seiichi; Komori, Masataka; Koyama, Shuji; Morishita, Yuki; Sekihara, Eri; Akagi, Takashi; Yamashita, Tomohiro; Toshito, Toshiyuki

    2016-01-01

    Purpose: The authors previously reported successful luminescence imaging of water during proton irradiation and its application to range estimation. However, since the feasibility of this approach for carbon-ion irradiation remained unclear, the authors conducted luminescence imaging during carbon-ion irradiation and estimated the ranges. Methods: The authors placed a pure-water phantom on the patient couch of a carbon-ion therapy system and measured the luminescence images with a high-sensitivity, cooled charge-coupled device camera during carbon-ion irradiation. The authors also carried out imaging of three types of phantoms (tap-water, an acrylic block, and a plastic scintillator) and compared their intensities and distributions with those of a phantom containing pure-water. Results: The luminescence images of pure-water phantoms during carbon-ion irradiation showed clear Bragg peaks, and the measured carbon-ion ranges from the images were almost the same as those obtained by simulation. The image of the tap-water phantom showed almost the same distribution as that of the pure-water phantom. The acrylic block phantom’s luminescence image produced seven times higher luminescence and had a 13% shorter range than that of the water phantoms; the range with the acrylic phantom generally matched the calculated value. The plastic scintillator showed ∼15 000 times higher light than that of water. Conclusions: Luminescence imaging during carbon-ion irradiation of water is not only possible but also a promising method for range estimation in carbon-ion therapy.

  7. [Carbon storage of forest stands in Shandong Province estimated by forestry inventory data].

    Science.gov (United States)

    Li, Shi-Mei; Yang, Chuan-Qiang; Wang, Hong-Nian; Ge, Li-Qiang

    2014-08-01

    Based on the 7th forestry inventory data of Shandong Province, this paper estimated the carbon storage and carbon density of forest stands, and analyzed their distribution characteristics according to dominant tree species, age groups and forest category using the volume-derived biomass method and average-biomass method. In 2007, the total carbon storage of the forest stands was 25. 27 Tg, of which the coniferous forests, mixed conifer broad-leaved forests, and broad-leaved forests accounted for 8.6%, 2.0% and 89.4%, respectively. The carbon storage of forest age groups followed the sequence of young forests > middle-aged forests > mature forests > near-mature forests > over-mature forests. The carbon storage of young forests and middle-aged forests accounted for 69.3% of the total carbon storage. Timber forest, non-timber product forest and protection forests accounted for 37.1%, 36.3% and 24.8% of the total carbon storage, respectively. The average carbon density of forest stands in Shandong Province was 10.59 t x hm(-2), which was lower than the national average level. This phenomenon was attributed to the imperfect structure of forest types and age groups, i. e., the notably higher percentage of timber forests and non-timber product forest and the excessively higher percentage of young forests and middle-aged forest than mature forests.

  8. Carbon pool densities and a first estimate of the total carbon pool in the Mongolian forest-steppe.

    Science.gov (United States)

    Dulamsuren, Choimaa; Klinge, Michael; Degener, Jan; Khishigjargal, Mookhor; Chenlemuge, Tselmeg; Bat-Enerel, Banzragch; Yeruult, Yolk; Saindovdon, Davaadorj; Ganbaatar, Kherlenchimeg; Tsogtbaatar, Jamsran; Leuschner, Christoph; Hauck, Markus

    2016-02-01

    The boreal forest biome represents one of the most important terrestrial carbon stores, which gave reason to intensive research on carbon stock densities. However, such an analysis does not yet exist for the southernmost Eurosiberian boreal forests in Inner Asia. Most of these forests are located in the Mongolian forest-steppe, which is largely dominated by Larix sibirica. We quantified the carbon stock density and total carbon pool of Mongolia's boreal forests and adjacent grasslands and draw conclusions on possible future change. Mean aboveground carbon stock density in the interior of L. sibirica forests was 66 Mg C ha(-1) , which is in the upper range of values reported from boreal forests and probably due to the comparably long growing season. The density of soil organic carbon (SOC, 108 Mg C ha(-1) ) and total belowground carbon density (149 Mg C ha(-1) ) are at the lower end of the range known from boreal forests, which might be the result of higher soil temperatures and a thinner permafrost layer than in the central and northern boreal forest belt. Land use effects are especially relevant at forest edges, where mean carbon stock density was 188 Mg C ha(-1) , compared with 215 Mg C ha(-1) in the forest interior. Carbon stock density in grasslands was 144 Mg C ha(-1) . Analysis of satellite imagery of the highly fragmented forest area in the forest-steppe zone showed that Mongolia's total boreal forest area is currently 73 818 km(2) , and 22% of this area refers to forest edges (defined as the first 30 m from the edge). The total forest carbon pool of Mongolia was estimated at ~ 1.5-1.7 Pg C, a value which is likely to decrease in future with increasing deforestation and fire frequency, and global warming. © 2015 John Wiley & Sons Ltd.

  9. Drought stress and tree size determine stem CO2 efflux in a tropical forest.

    Science.gov (United States)

    Rowland, Lucy; da Costa, Antonio C L; Oliveira, Alex A R; Oliveira, Rafael S; Bittencourt, Paulo L; Costa, Patricia B; Giles, Andre L; Sosa, Azul I; Coughlin, Ingrid; Godlee, John L; Vasconcelos, Steel S; Junior, João A S; Ferreira, Leandro V; Mencuccini, Maurizio; Meir, Patrick

    2018-06-01

    CO 2 efflux from stems (CO 2_stem ) accounts for a substantial fraction of tropical forest gross primary productivity, but the climate sensitivity of this flux remains poorly understood. We present a study of tropical forest CO 2_stem from 215 trees across wet and dry seasons, at the world's longest running tropical forest drought experiment site. We show a 27% increase in wet season CO 2_stem in the droughted forest relative to a control forest. This was driven by increasing CO 2_stem in trees 10-40 cm diameter. Furthermore, we show that drought increases the proportion of maintenance to growth respiration in trees > 20 cm diameter, including large increases in maintenance respiration in the largest droughted trees, > 40 cm diameter. However, we found no clear taxonomic influence on CO 2_stem and were unable to accurately predict how drought sensitivity altered ecosystem scale CO 2_stem , due to substantial uncertainty introduced by contrasting methods previously employed to scale CO 2_stem fluxes. Our findings indicate that under future scenarios of elevated drought, increases in CO 2_stem may augment carbon losses, weakening or potentially reversing the tropical forest carbon sink. However, due to substantial uncertainties in scaling CO 2_stem fluxes, stand-scale future estimates of changes in stem CO 2 emissions remain highly uncertain. © 2018 The Authors New Phytologist © 2018 New Phytologist Trust.

  10. Improved Forest Biomass and Carbon Estimations Using Texture Measures from WorldView-2 Satellite Data

    Directory of Open Access Journals (Sweden)

    Sandra Eckert

    2012-03-01

    Full Text Available Accurate estimation of aboveground biomass and carbon stock has gained importance in the context of the United Nations Framework Convention on Climate Change (UNFCCC and the Kyoto Protocol. In order to develop improved forest stratum–specific aboveground biomass and carbon estimation models for humid rainforest in northeast Madagascar, this study analyzed texture measures derived from WorldView-2 satellite data. A forest inventory was conducted to develop stratum-specific allometric equations for dry biomass. On this basis, carbon was calculated by applying a conversion factor. After satellite data preprocessing, vegetation indices, principal components, and texture measures were calculated. The strength of their relationships with the stratum-specific plot data was analyzed using Pearson’s correlation. Biomass and carbon estimation models were developed by performing stepwise multiple linear regression. Pearson’s correlation coefficients revealed that (a texture measures correlated more with biomass and carbon than spectral parameters, and (b correlations were stronger for degraded forest than for non-degraded forest. For degraded forest, the texture measures of Correlation, Angular Second Moment, and Contrast, derived from the red band, contributed to the best estimation model, which explained 84% of the variability in the field data (relative RMSE = 6.8%. For non-degraded forest, the vegetation index EVI and the texture measures of Variance, Mean, and Correlation, derived from the newly introduced coastal blue band, both NIR bands, and the red band, contributed to the best model, which explained 81% of the variability in the field data (relative RMSE = 11.8%. These results indicate that estimation of tropical rainforest biomass/carbon, based on very high resolution satellite data, can be improved by (a developing and applying forest stratum–specific models, and (b including textural information in addition to spectral information.

  11. Carbon storage estimation of main forestry ecosystems in Northwest Yunnan Province using remote sensing data

    Science.gov (United States)

    Wang, Jinliang; Wang, Xiaohua; Yue, Cairong; Xu, Tian-shu; Cheng, Pengfei

    2014-05-01

    Estimating regional forest organic carbon pool has became a hot issue in the study of forest ecosystem carbon cycle. The forest ecosystem in Shangri-La County, Northwest Yunnan Province, are well preserved, and the area of Picea Likiangensis, Quercus Aquifolioides, Pinus Densata and Pinus Yunnanensis amounts to 80% of the total arboreal forest area in Shangri-La County. Based on the field measurements, remote sensing data and GIS analysis, three models were established for carbon storage estimation. The remote sensing information model with the highest accuracy were used to calculate the carbon storages of the four main forest ecosystems. The results showed: (1) the total carbon storage of the four forest ecosystems in Shangri-La is 302.984 TgC, in which tree layer, shrub layer, herb layer, litter layer, soil layer are 60.196TgC, 5.433TgC, 1.080TgC, 3.582TgC and 232.692TgC, accounting for 19.87%, 1.79%, 0.36%, 1.18%, 76.80% of the total carbon storage respectively. (2)The order of the carbon storage from high to low is soil layer, tree layer, shrub layer, litter layer and herb layer respectively for the four main forest ecosystems. (3)The total average carbon density of the four main forest ecosystems is 403.480 t/hm2, and the carbon densities of the Picea Likiangensis, Quercus Aquifolioides, Pinus Densata and Pinus Yunnanensis are 576.889 t/hm2, 326.947 t/hm2, 279.993 t/hm2 and 255.792 t/hm2 respectively.

  12. Evaluations of carbon fluxes estimated by top-down and bottom-up approaches

    Science.gov (United States)

    Murakami, K.; Sasai, T.; Kato, S.; Hiraki, K.; Maksyutov, S. S.; Yokota, T.; Nasahara, K.; Matsunaga, T.

    2013-12-01

    There are two types of estimating carbon fluxes using satellite observation data, and these are referred to as top-down and bottom-up approaches. Many uncertainties are however still remain in these carbon flux estimations, because the true values of carbon flux are still unclear and estimations vary according to the type of the model (e.g. a transport model, a process based model) and input data. The CO2 fluxes in these approaches are estimated by using different satellite data such as the distribution of CO2 concentration in the top-down approach and the land cover information (e.g. leaf area, surface temperature) in the bottom-up approach. The satellite-based CO2 flux estimations with reduced uncertainty can be used efficiently for identifications of large emission area and carbon stocks of forest area. In this study, we evaluated the carbon flux estimates from two approaches by comparing with each other. The Greenhouse gases Observing SATellite (GOSAT) has been observing atmospheric CO2 concentrations since 2009. GOSAT L4A data product is the monthly CO2 flux estimations for 64 sub-continental regions and is estimated by using GOSAT FTS SWIR L2 XCO2 data and atmospheric tracer transport model. We used GOSAT L4A CO2 flux as top-down approach estimations and net ecosystem productions (NEP) estimated by the diagnostic type biosphere model BEAMS as bottom-up approach estimations. BEAMS NEP is only natural land CO2 flux, so we used GOSAT L4A CO2 flux after subtraction of anthropogenic CO2 emissions and oceanic CO2 flux. We compared with two approach in temperate north-east Asia region. This region is covered by grassland and crop land (about 60 %), forest (about 20 %) and bare ground (about 20 %). The temporal variation for one year period was indicated similar trends between two approaches. Furthermore we show the comparison of CO2 flux estimations in other sub-continental regions.

  13. Estimation of niobium, tantalum and zirconium in a carbonate rich ore

    International Nuclear Information System (INIS)

    Navale, A.S.; Venkatakrishnan, R.R.; Sreenivas, T.

    2013-01-01

    A simple method using ICP-OES for estimation of tantalum, niobium and zirconium in a carbonate rich matrix is described. The sample is boiled with 10% v/v hydrochloric acid for 15 min and filtered. The residue is fused with ammonium bifluoride-ammonium sulphate flux and the melt is leached with water. Nb, Ta and Zr are estimated in the water leach by ICP-OES. (author)

  14. Remote Sensing of Vegetation Nitrogen Content for Spatially Explicit Carbon and Water Cycle Estimation

    Science.gov (United States)

    Zhang, Y. L.; Miller, J. R.; Chen, J. M.

    2009-05-01

    Foliage nitrogen concentration is a determinant of photosynthetic capacity of leaves, thereby an important input to ecological models for estimating terrestrial carbon and water budgets. Recently, spectrally continuous airborne hyperspectral remote sensing imagery has proven to be useful for retrieving an important related parameter, total chlorophyll content at both leaf and canopy scales. Thus remote sensing of vegetation biochemical parameters has promising potential for improving the prediction of global carbon and water balance patterns. In this research, we explored the feasibility of estimating leaf nitrogen content using hyperspectral remote sensing data for spatially explicit estimation of carbon and water budgets. Multi-year measurements of leaf biochemical contents of seven major boreal forest species were carried out in northeastern Ontario, Canada. The variation of leaf chlorophyll and nitrogen content in response to various growth conditions, and the relationship between them,were investigated. Despite differences in plant type (deciduous and evergreen), leaf age, stand growth conditions and developmental stages, leaf nitrogen content was strongly correlated with leaf chlorophyll content on a mass basis during the active growing season (r2=0.78). With this general correlation, leaf nitrogen content was estimated from leaf chlorophyll content at an accuracy of RMSE=2.2 mg/g, equivalent to 20.5% of the average measured leaf nitrogen content. Based on this correlation and a hyperspectral remote sensing algorithm for leaf chlorophyll content retrieval, the spatial variation of leaf nitrogen content was inferred from the airborne hyperspectral remote sensing imagery acquired by Compact Airborne Spectrographic Imager (CASI). A process-based ecological model Boreal Ecosystem Productivity Simulator (BEPS) was used for estimating terrestrial carbon and water budgets. In contrast to the scenario with leaf nitrogen content assigned as a constant value without

  15. Estimate of China's energy carbon emissions peak and analysis on electric power carbon emissions

    Directory of Open Access Journals (Sweden)

    Zhi-Xuan Wang

    2014-12-01

    Full Text Available China's energy carbon emissions are projected to peak in 2030 with approximately 110% of its 2020 level under the following conditions: 1 China's gross primary energy consumption is 5 Gtce in 2020 and 6 Gtce in 2030; 2 coal's share of the energy consumption is 61% in 2020 and 55% in 2030; 3 non-fossil energy's share increases from 15% in 2020 to 20% in 2030; 4 through 2030, China's GDP grows at an average annual rate of 6%; 5 the annual energy consumption elasticity coefficient is 0.30 in average; and 6 the annual growth rate of energy consumption steadily reduces to within 1%. China's electricity generating capacity would be 1,990 GW, with 8,600 TW h of power generation output in 2020. Of that output 66% would be from coal, 5% from gas, and 29% from non-fossil energy. By 2030, electricity generating capacity would reach 3,170 GW with 11,900 TW h of power generation output. Of that output, 56% would be from coal, 6% from gas, and 37% from non-fossil energy. From 2020 to 2030, CO2 emissions from electric power would relatively fall by 0.2 Gt due to lower coal consumption, and relatively fall by nearly 0.3 Gt with the installation of more coal-fired cogeneration units. During 2020–2030, the portion of carbon emissions from electric power in China's energy consumption is projected to increase by 3.4 percentage points. Although the carbon emissions from electric power would keep increasing to 118% of the 2020 level in 2030, the electric power industry would continue to play a decisive role in achieving the goal of increase in non-fossil energy use. This study proposes countermeasures and recommendations to control carbon emissions peak, including energy system optimization, green-coal-fired electricity generation, and demand side management.

  16. Flood effects on efflux and net production of nitrous oxide in river floodplain soils

    Science.gov (United States)

    Riaz, Muhammad; Bruderer, Christian; Niklaus, Pascal A.; Luster, Jörg

    2016-04-01

    Floodplain soils are often rich in nutrients and exhibit high spatial heterogeneity in terms of geomorphology, soil environmental conditions and substrate availability for processes involved in carbon and nutrient cycling. In addition, fluctuating water tables lead to temporally changing redox conditions. In such systems, there are ideal conditions for the occurrence of hot spots and moments of nitrous oxide emissions, a potent greenhouse gas. The factors that govern the spatial heterogeneity and dynamics of N2O formation in floodplain soils and the surface efflux of this gas are not fully understood. A particular issue is the contribution of N2O formation in the subsoil to surface efflux. We studied this question in the floodplain of a restored section of the Thur river (NE Switzerland) which is characterized by a flashy flow regime. As a consequence, the floodplain soils are unsaturated most of the time. We showed earlier that saturation during flood pulses leads to short phases of generally anoxic conditions followed by a drying phase with anoxic conditions within aggregates and oxic conditions in larger soil pores. The latter conditions are conducive for spatially closely-coupled nitrification-denitrification and related hot moments of nitrous oxide formation. In a floodplain zone characterized by about one meter of young, sandy sediments, that are mostly covered by the tall grass Phalaris arundinacea, we measured at several time points before and after a small flood event N2O surface efflux with the closed-chamber method, and assessed N2O concentrations in the soil air at four different depths using gas-permeable tubings. In addition, we calculated the N2O diffusivity in the soil from Radon diffusivity. The latter was estimated in-situ from the recovery of Radon concentration in the gas-permeable tubings after purging with ambient air. All these data were then used to calculate net N2O production rates at different soil depths with the gradient method. In

  17. Model Effects on GLAS-Based Regional Estimates of Forest Biomass and Carbon

    Science.gov (United States)

    Nelson, Ross F.

    2010-01-01

    Ice, Cloud, and land Elevation Satellite (ICESat) / Geosciences Laser Altimeter System (GLAS) waveform data are used to estimate biomass and carbon on a 1.27 X 10(exp 6) square km study area in the Province of Quebec, Canada, below the tree line. The same input datasets and sampling design are used in conjunction with four different predictive models to estimate total aboveground dry forest biomass and forest carbon. The four models include non-stratified and stratified versions of a multiple linear model where either biomass or (biomass)(exp 0.5) serves as the dependent variable. The use of different models in Quebec introduces differences in Provincial dry biomass estimates of up to 0.35 G, with a range of 4.94 +/- 0.28 Gt to 5.29 +/-0.36 Gt. The differences among model estimates are statistically non-significant, however, and the results demonstrate the degree to which carbon estimates vary strictly as a function of the model used to estimate regional biomass. Results also indicate that GLAS measurements become problematic with respect to height and biomass retrievals in the boreal forest when biomass values fall below 20 t/ha and when GLAS 75th percentile heights fall below 7 m.

  18. Estimating carbon and showing impacts of drought using satellite data in regression-tree models

    Science.gov (United States)

    Boyte, Stephen; Wylie, Bruce K.; Howard, Danny; Dahal, Devendra; Gilmanov, Tagir G.

    2018-01-01

    Integrating spatially explicit biogeophysical and remotely sensed data into regression-tree models enables the spatial extrapolation of training data over large geographic spaces, allowing a better understanding of broad-scale ecosystem processes. The current study presents annual gross primary production (GPP) and annual ecosystem respiration (RE) for 2000–2013 in several short-statured vegetation types using carbon flux data from towers that are located strategically across the conterminous United States (CONUS). We calculate carbon fluxes (annual net ecosystem production [NEP]) for each year in our study period, which includes 2012 when drought and higher-than-normal temperatures influence vegetation productivity in large parts of the study area. We present and analyse carbon flux dynamics in the CONUS to better understand how drought affects GPP, RE, and NEP. Model accuracy metrics show strong correlation coefficients (r) (r ≥ 94%) between training and estimated data for both GPP and RE. Overall, average annual GPP, RE, and NEP are relatively constant throughout the study period except during 2012 when almost 60% less carbon is sequestered than normal. These results allow us to conclude that this modelling method effectively estimates carbon dynamics through time and allows the exploration of impacts of meteorological anomalies and vegetation types on carbon dynamics.

  19. Allometric Equations for Estimating Carbon Stocks in Natural Forest in New Zealand

    Directory of Open Access Journals (Sweden)

    Andrea Brandon

    2012-09-01

    Full Text Available Species-specific and mixed-species volume and above ground biomass allometric equations were developed for 15 indigenous tree species and four tree fern species in New Zealand. A mixed-species tree equation based on breast height diameter (DBH and tree height (H provided acceptable estimates of stem plus branch (>10 cm in diameter over bark volume, which was multiplied by live tree density to estimate dry matter. For dead standing spars, DBH, estimated original height, actual spar height and compatible volume/taper functions provided estimates of dead stem volume, which was multiplied by live tree density and a density modifier based on log decay class from field assessments to estimate dry matter. Live tree density was estimated using ratio estimators. Ratio estimators were based on biomass sample trees, and utilized density data from outerwood basic density surveys which were available for 35 tree species sampled throughout New Zealand. Foliage and branch ( < 10 cm in diameter over bark dry matter were estimated directly from tree DBH. Tree fern above ground dry matter was estimated using allometric equations based on DBH and H. Due to insufficient data, below ground carbon for trees was estimated using the default IPCC root/shoot ratio of 25%, but for tree ferns it was estimated using measured root/shoot ratios which averaged 20%.

  20. Incorporating climate into belowground carbon estimates in the national greenhouse gas inventory

    Science.gov (United States)

    Matthew B. Russell; Grant M. Domke; Christopher W. Woodall; Anthony W. D’Amato

    2015-01-01

    Refined estimation of carbon (C) stocks within forest ecosystems is a critical component of efforts to reduce greenhouse gas emissions and mitigate the effects of projected climate change through forest C management. Recent evidence has pointed to the importance of climate as a driver of belowground C stocks. This study describes an approach for adjusting allometric...

  1. Top-down estimates of biomass burning emissions of black carbon in the western United States

    Science.gov (United States)

    Y. H. Mao; Q. B. Li; D. Chen; L. Zhang; W. -M. Hao; K.-N. Liou

    2014-01-01

    We estimate biomass burning and anthropogenic emissions of black carbon (BC) in the western US for May-October 2006 by inverting surface BC concentrations from the Interagency Monitoring of PROtected Visual Environment (IMPROVE) network using a global chemical transport model. We first use active fire counts from the Moderate Resolution Imaging Spectroradiometer (MODIS...

  2. Soil carbon storage estimation in a forested watershed using quantitative soil-landscape modeling

    Science.gov (United States)

    James A. Thompson; Randall K. Kolka

    2005-01-01

    Carbon storage in soils is important to forest ecosystems. Moreover, forest soils may serve as important C sinks for ameliorating excess atmospheric CO2. Spatial estimates of soil organic C (SOC) storage have traditionally relied upon soil survey maps and laboratory characterization data. This approach does not account for inherent variability...

  3. Towards regional, error-bounded landscape carbon storage estimates for data-deficient areas of the world.

    Directory of Open Access Journals (Sweden)

    Simon Willcock

    Full Text Available Monitoring landscape carbon storage is critical for supporting and validating climate change mitigation policies. These may be aimed at reducing deforestation and degradation, or increasing terrestrial carbon storage at local, regional and global levels. However, due to data-deficiencies, default global carbon storage values for given land cover types such as 'lowland tropical forest' are often used, termed 'Tier 1 type' analyses by the Intergovernmental Panel on Climate Change (IPCC. Such estimates may be erroneous when used at regional scales. Furthermore uncertainty assessments are rarely provided leading to estimates of land cover change carbon fluxes of unknown precision which may undermine efforts to properly evaluate land cover policies aimed at altering land cover dynamics. Here, we present a repeatable method to estimate carbon storage values and associated 95% confidence intervals (CI for all five IPCC carbon pools (aboveground live carbon, litter, coarse woody debris, belowground live carbon and soil carbon for data-deficient regions, using a combination of existing inventory data and systematic literature searches, weighted to ensure the final values are regionally specific. The method meets the IPCC 'Tier 2' reporting standard. We use this method to estimate carbon storage over an area of33.9 million hectares of eastern Tanzania, reporting values for 30 land cover types. We estimate that this area stored 6.33 (5.92-6.74 Pg C in the year 2000. Carbon storage estimates for the same study area extracted from five published Africa-wide or global studies show a mean carbon storage value of ∼50% of that reported using our regional values, with four of the five studies reporting lower carbon storage values. This suggests that carbon storage may have been underestimated for this region of Africa. Our study demonstrates the importance of obtaining regionally appropriate carbon storage estimates, and shows how such values can be produced

  4. Estimation of carbon sequestration by tree species in three farms in Villa Clara province

    Directory of Open Access Journals (Sweden)

    José Carlos García Hernández

    2016-03-01

    Full Text Available The research took place in two farms of the Cifuentes municipality and in a farm of the Santa Clara municipality, province of Villa Clara. It was carried out from November 2008 to May 2009, with the objective of estimating the capture of Carbon by common arboreal species in these farms. The plant biomass analyses were made according to the methodology of Mercadet and Álvarez (2005. Several parameters were analyzed. Age, height and perimeter of the plants were the most influential parameters on the amount of carbon sequestered. In this regard, we performed a multivariate curve fitting, showing the age of the plants the highest percent of dependence (54.89%. Palma Real with values between 0.81 and 0.84 t / plant and the Mango between 0.60 and 0.81 t /plant of retained Carbon, were the most outstanding in the capture of Carbon.

  5. Urban energy consumption and related carbon emission estimation: a study at the sector scale

    Science.gov (United States)

    Lu, Weiwei; Chen, Chen; Su, Meirong; Chen, Bin; Cai, Yanpeng; Xing, Tao

    2013-12-01

    With rapid economic development and energy consumption growth, China has become the largest energy consumer in the world. Impelled by extensive international concern, there is an urgent need to analyze the characteristics of energy consumption and related carbon emission, with the objective of saving energy, reducing carbon emission, and lessening environmental impact. Focusing on urban ecosystems, the biggest energy consumer, a method for estimating energy consumption and related carbon emission was established at the urban sector scale in this paper. Based on data for 1996-2010, the proposed method was applied to Beijing in a case study to analyze the consumption of different energy resources (i.e., coal, oil, gas, and electricity) and related carbon emission in different sectors (i.e., agriculture, industry, construction, transportation, household, and service sectors). The results showed that coal and oil contributed most to energy consumption and carbon emission among different energy resources during the study period, while the industrial sector consumed the most energy and emitted the most carbon among different sectors. Suggestions were put forward for energy conservation and emission reduction in Beijing. The analysis of energy consumption and related carbon emission at the sector scale is helpful for practical energy saving and emission reduction in urban ecosystems.

  6. Synthesizing Global and Local Datasets to Estimate Jurisdictional Forest Carbon Fluxes in Berau, Indonesia.

    Science.gov (United States)

    Griscom, Bronson W; Ellis, Peter W; Baccini, Alessandro; Marthinus, Delon; Evans, Jeffrey S; Ruslandi

    2016-01-01

    Forest conservation efforts are increasingly being implemented at the scale of sub-national jurisdictions in order to mitigate global climate change and provide other ecosystem services. We see an urgent need for robust estimates of historic forest carbon emissions at this scale, as the basis for credible measures of climate and other benefits achieved. Despite the arrival of a new generation of global datasets on forest area change and biomass, confusion remains about how to produce credible jurisdictional estimates of forest emissions. We demonstrate a method for estimating the relevant historic forest carbon fluxes within the Regency of Berau in eastern Borneo, Indonesia. Our method integrates best available global and local datasets, and includes a comprehensive analysis of uncertainty at the regency scale. We find that Berau generated 8.91 ± 1.99 million tonnes of net CO2 emissions per year during 2000-2010. Berau is an early frontier landscape where gross emissions are 12 times higher than gross sequestration. Yet most (85%) of Berau's original forests are still standing. The majority of net emissions were due to conversion of native forests to unspecified agriculture (43% of total), oil palm (28%), and fiber plantations (9%). Most of the remainder was due to legal commercial selective logging (17%). Our overall uncertainty estimate offers an independent basis for assessing three other estimates for Berau. Two other estimates were above the upper end of our uncertainty range. We emphasize the importance of including an uncertainty range for all parameters of the emissions equation to generate a comprehensive uncertainty estimate-which has not been done before. We believe comprehensive estimates of carbon flux uncertainty are increasingly important as national and international institutions are challenged with comparing alternative estimates and identifying a credible range of historic emissions values.

  7. Estimating California ecosystem carbon change using process model and land cover disturbance data: 1951-2000

    Science.gov (United States)

    Liu, Jinxun; Vogelmann, James E.; Zhu, Zhiliang; Key, Carl H.; Sleeter, Benjamin M.; Price, D.T.; Chen, Jing M.; Cochrane, Mark A.; Eidenshink, Jeffery C.; Howard, Stephen M.; Bliss, Norman B.; Jiang, Hong

    2011-01-01

    Land use change, natural disturbance, and climate change directly alter ecosystem productivity and carbon stock level. The estimation of ecosystem carbon dynamics depends on the quality of land cover change data and the effectiveness of the ecosystem models that represent the vegetation growth processes and disturbance effects. We used the Integrated Biosphere Simulator (IBIS) and a set of 30- to 60-m resolution fire and land cover change data to examine the carbon changes of California's forests, shrublands, and grasslands. Simulation results indicate that during 1951–2000, the net primary productivity (NPP) increased by 7%, from 72.2 to 77.1 Tg C yr−1 (1 teragram = 1012 g), mainly due to CO2 fertilization, since the climate hardly changed during this period. Similarly, heterotrophic respiration increased by 5%, from 69.4 to 73.1 Tg C yr−1, mainly due to increased forest soil carbon and temperature. Net ecosystem production (NEP) was highly variable in the 50-year period but on average equalled 3.0 Tg C yr−1 (total of 149 Tg C). As with NEP, the net biome production (NBP) was also highly variable but averaged −0.55 Tg C yr−1 (total of –27.3 Tg C) because NBP in the 1980s was very low (–5.34 Tg C yr−1). During the study period, a total of 126 Tg carbon were removed by logging and land use change, and 50 Tg carbon were directly removed by wildland fires. For carbon pools, the estimated total living upper canopy (tree) biomass decreased from 928 to 834 Tg C, and the understory (including shrub and grass) biomass increased from 59 to 63 Tg C. Soil carbon and dead biomass carbon increased from 1136 to 1197 Tg C.Our analyses suggest that both natural and human processes have significant influence on the carbon change in California. During 1951–2000, climate interannual variability was the key driving force for the large interannual changes of ecosystem carbon source and sink at the state level, while logging and fire

  8. Carbon dioxide and methane measurements from the Los Angeles Megacity Carbon Project - Part 1: calibration, urban enhancements, and uncertainty estimates

    Science.gov (United States)

    Verhulst, Kristal R.; Karion, Anna; Kim, Jooil; Salameh, Peter K.; Keeling, Ralph F.; Newman, Sally; Miller, John; Sloop, Christopher; Pongetti, Thomas; Rao, Preeti; Wong, Clare; Hopkins, Francesca M.; Yadav, Vineet; Weiss, Ray F.; Duren, Riley M.; Miller, Charles E.

    2017-07-01

    We report continuous surface observations of carbon dioxide (CO2) and methane (CH4) from the Los Angeles (LA) Megacity Carbon Project during 2015. We devised a calibration strategy, methods for selection of background air masses, calculation of urban enhancements, and a detailed algorithm for estimating uncertainties in urban-scale CO2 and CH4 measurements. These methods are essential for understanding carbon fluxes from the LA megacity and other complex urban environments globally. We estimate background mole fractions entering LA using observations from four extra-urban sites including two marine sites located south of LA in La Jolla (LJO) and offshore on San Clemente Island (SCI), one continental site located in Victorville (VIC), in the high desert northeast of LA, and one continental/mid-troposphere site located on Mount Wilson (MWO) in the San Gabriel Mountains. We find that a local marine background can be established to within ˜ 1 ppm CO2 and ˜ 10 ppb CH4 using these local measurement sites. Overall, atmospheric carbon dioxide and methane levels are highly variable across Los Angeles. Urban and suburban sites show moderate to large CO2 and CH4 enhancements relative to a marine background estimate. The USC (University of Southern California) site near downtown LA exhibits median hourly enhancements of ˜ 20 ppm CO2 and ˜ 150 ppb CH4 during 2015 as well as ˜ 15 ppm CO2 and ˜ 80 ppb CH4 during mid-afternoon hours (12:00-16:00 LT, local time), which is the typical period of focus for flux inversions. The estimated measurement uncertainty is typically better than 0.1 ppm CO2 and 1 ppb CH4 based on the repeated standard gas measurements from the LA sites during the last 2 years, similar to Andrews et al. (2014). The largest component of the measurement uncertainty is due to the single-point calibration method; however, the uncertainty in the background mole fraction is much larger than the measurement uncertainty. The background uncertainty for the marine

  9. Drug efflux proteins in multidrug resistant bacteria

    NARCIS (Netherlands)

    vanVeen, HW; Konings, WN

    Bacteria contain an array of transport proteins in their cytoplasmic membrane. Many of these proteins play an important role in conferring resistance to toxic compounds. The multidrug efflux systems encountered in prokaryotic cells are very similar to those observed in eukaryotic cells. Therefore, a

  10. New methods for the identification of efflux mediated MDR bacteria, genetic assessment of regulators and efflux pump constituents, characterization of efflux systems and screening for inhibitors of efflux pumps

    DEFF Research Database (Denmark)

    Viveiros, M; Martins, M; Couto, I

    2008-01-01

    We have developed a number of methods that identify efflux pump mediated multi-drug resistant bacteria, characterize efflux systems and screen for inhibitors of efflux pumps. These approaches were complemented by the quantification of the expression of genes that regulate and code for constituents...

  11. Substrate specificities and efflux efficiencies of RND efflux pumps of Acinetobacter baumannii.

    Science.gov (United States)

    Leus, Inga V; Weeks, Jon W; Bonifay, Vincent; Smith, Lauren; Richardson, Sophie; Zgurskaya, Helen I

    2018-04-16

    Antibiotic resistant Acinetobacter baumannii causes infections that are extremely difficult to treat. A significant role in these resistance profiles is attributed to multidrug efflux pumps, especially those belonging to Resistance-Nodulation-cell Division (RND) superfamily of transporters. In this study, we analyzed functions and properties of RND efflux pumps in A. baumannii ATCC 17978. This strain is susceptible to antibiotics and does not contain mutations that are commonly selected upon exposure to high concentrations of antibiotics. We constructed derivatives of ATCC 17978 lacking chromosomally encoded RND pumps and complemented these strains by the plasmid-borne genes. We analyzed the substrate selectivities and efficiencies of the individual pumps in the context of native outer membranes and their hyperporinated variants. Our results show that inactivation of AdeIJK provides the strongest potentiation of antibiotic activities, whereas inactivation of AdeFGH triggers the overexpression of AdeAB. The plasmid-borne overproduction complements the hypersusceptible phenotypes of the efflux deletion mutants to the levels of the parental ATCC 17978. Only a few antibiotics strongly benefitted from the overproduction of efflux pumps and antibacterial activities of some of those depended on the synergistic interaction with the low permeability barrier of the outer membrane. Either overproduction or inactivation of efflux pumps change dramatically the lipidome of ATCC 17978. We conclude that efflux pumps of A. baumannii are tightly integrated into physiology of this bacterium and that clinical levels of antibiotic resistance in A. baumannii isolates are unlikely to be reached solely due to overproduction of RND efflux pumps. Importance RND-type efflux pumps are important contributors in development of clinical antibiotic resistance in A. baumannii However, their specific roles and the extent of contribution to antibiotic resistance remain unclear. We analyzed

  12. A Greenhouse Gas and Soil Carbon Model for Estimating the Carbon Footprint of Livestock Production in Canada

    Science.gov (United States)

    Vergé, Xavier P.C.; Dyer, James A.; Worth, Devon E.; Smith, Ward N.; Desjardins, Raymond L.; McConkey, Brian G.

    2012-01-01

    Simple Summary We developed a model to estimate the carbon footprint of Canadian livestock production. To include long term soil carbon storage and loss potential we introduced a payback period concept. The model was tested by reallocating 10% only of the protein production from a ruminant to a non ruminant source to minimize the risk of including rangeland or marginal lands. This displacement generated residual land which was found to play a major role in the potential mitigation of GHG emissions. The model will allow land use policies aimed at reducing the agricultural GHG emissions to be assessed. Abstract To assess tradeoffs between environmental sustainability and changes in food production on agricultural land in Canada the Unified Livestock Industry and Crop Emissions Estimation System (ULICEES) was developed. It incorporates four livestock specific GHG assessments in a single model. To demonstrate the application of ULICEES, 10% of beef cattle protein production was assumed to be displaced with an equivalent amount of pork protein. Without accounting for the loss of soil carbon, this 10% shift reduced GHG emissions by 2.5 TgCO2e y−1. The payback period was defined as the number of years required for a GHG reduction to equal soil carbon lost from the associated land use shift. A payback period that is shorter than 40 years represents a net long term decrease in GHG emissions. Displacing beef cattle with hogs resulted in a surplus area of forage. When this residual land was left in ungrazed perennial forage, the payback periods were less than 4 years and when it was reseeded to annual crops, they were equal to or less than 40 years. They were generally greater than 40 years when this land was used to raise cattle. Agricultural GHG mitigation policies will inevitably involve a trade-off between production, land use and GHG emission reduction. ULICEES is a model that can objectively assess these trade-offs for Canadian agriculture. PMID:26487032

  13. Estimating carbon sequestration in the piedmont ecoregion of the United States from 1971 to 2010

    Science.gov (United States)

    Liu, Jinxun; Sleeter, Benjamin M.; Zhu, Zhiliang; Heath, Linda S.; Tan, Zhengxi; Wilson, Tamara; Sherba, Jason T.; Zhou, Decheng

    2016-01-01

    Background: Human activities have diverse and profound impacts on ecosystem carbon cycles. The Piedmont ecoregion in the eastern United States has undergone significant land use and land cover change in the past few decades. The purpose of this study was to use newly available land use and land cover change data to quantify carbon changes within the ecoregion. Land use and land cover change data (60-m spatial resolution) derived from sequential remotely sensed Landsat imagery were used to generate 960-m resolution land cover change maps for the Piedmont ecoregion. These maps were used in the Integrated Biosphere Simulator (IBIS) to simulate ecosystem carbon stock and flux changes from 1971 to 2010. Results: Results show that land use change, especially urbanization and forest harvest had significant impacts on carbon sources and sinks. From 1971 to 2010, forest ecosystems sequestered 0.25 Mg C ha−1 yr−1, while agricultural ecosystems sequestered 0.03 Mg C ha−1 yr−1. The total ecosystem C stock increased from 2271 Tg C in 1971 to 2402 Tg C in 2010, with an annual average increase of 3.3 Tg C yr−1. Conclusions: Terrestrial lands in the Piedmont ecoregion were estimated to be weak net carbon sink during the study period. The major factors contributing to the carbon sink were forest growth and afforestation; the major factors contributing to terrestrial emissions were human induced land cover change, especially urbanization and forest harvest. An additional amount of carbon continues to be stored in harvested wood products. If this pool were included the carbon sink would be stronger. Keywords: Land-use change, Carbon change, Piedmont ecoregion, IBIS model

  14. Towards Regional, Error-Bounded Landscape Carbon Storage Estimates for Data-Deficient Areas of the World

    DEFF Research Database (Denmark)

    Willcock, Simon; Phillips, Oliver L.; Platts, Philip J.

    2012-01-01

    estimates for the same study area extracted from five published Africa-wide or global studies show a mean carbon storage value of ∼50% of that reported using our regional values, with four of the five studies reporting lower carbon storage values. This suggests that carbon storage may have been...

  15. Validation and Intercomparison of Ocean Color Algorithms for Estimating Particulate Organic Carbon in the Oceans

    Directory of Open Access Journals (Sweden)

    Hayley Evers-King

    2017-08-01

    Full Text Available Particulate Organic Carbon (POC plays a vital role in the ocean carbon cycle. Though relatively small compared with other carbon pools, the POC pool is responsible for large fluxes and is linked to many important ocean biogeochemical processes. The satellite ocean-color signal is influenced by particle composition, size, and concentration and provides a way to observe variability in the POC pool at a range of temporal and spatial scales. To provide accurate estimates of POC concentration from satellite ocean color data requires algorithms that are well validated, with uncertainties characterized. Here, a number of algorithms to derive POC using different optical variables are applied to merged satellite ocean color data provided by the Ocean Color Climate Change Initiative (OC-CCI and validated against the largest database of in situ POC measurements currently available. The results of this validation exercise indicate satisfactory levels of performance from several algorithms (highest performance was observed from the algorithms of Loisel et al., 2002; Stramski et al., 2008 and uncertainties that are within the requirements of the user community. Estimates of the standing stock of the POC can be made by applying these algorithms, and yield an estimated mixed-layer integrated global stock of POC between 0.77 and 1.3 Pg C of carbon. Performance of the algorithms vary regionally, suggesting that blending of region-specific algorithms may provide the best way forward for generating global POC products.

  16. The soil classification and the subsurface carbon stock estimation with a ground-penetrating radar

    International Nuclear Information System (INIS)

    Onishi, K.; Rokugawa, S.; Kato, Y.

    2002-01-01

    One of the serious problems of the Kyoto Protocol is that we have no effective method to estimate the carbon stock of the subsurface. To solve this problem, we propose the application of ground-penetrating radar (GPR) to the subsurface soil survey. As a result, it is shown that GPR can detect the soil horizons, stones and roots. The fluctuations of the soil horizons in the forest are cleanly indicated as the reflection pattern of the microwaves. Considering the fact that the physical, chemical, and biological characteristics of each soil layer is almost unique, GPR results can be used to estimate the carbon stock in soil by combining with the vertical soil sample survey at one site. Then as a trial, we demonstrate to estimate the carbon content fixed in soil layers based on the soil samples and GPR survey data. we also compare this result with the carbon stock for the flat horizon case. The advantages of GPR usage for this object are not only the reduction of uncertainty and the cost, but also the environmental friendliness of survey manner. Finally, we summarize the adaptabilities of various antennas having different predominant frequencies for the shallow subsurface zone. (author)

  17. Providing low-budget estimations of carbon sequestration and greenhouse gas emissions in agricultural wetlands

    International Nuclear Information System (INIS)

    Lloyd, Colin R; Rebelo, Lisa-Maria; Max Finlayson, C

    2013-01-01

    The conversion of wetlands to agriculture through drainage and flooding, and the burning of wetland areas for agriculture have important implications for greenhouse gas (GHG) production and changing carbon stocks. However, the estimation of net GHG changes from mitigation practices in agricultural wetlands is complex compared to dryland crops. Agricultural wetlands have more complicated carbon and nitrogen cycles with both above- and below-ground processes and export of carbon via vertical and horizontal movement of water through the wetland. This letter reviews current research methodologies in estimating greenhouse gas production and provides guidance on the provision of robust estimates of carbon sequestration and greenhouse gas emissions in agricultural wetlands through the use of low cost reliable and sustainable measurement, modelling and remote sensing applications. The guidance is highly applicable to, and aimed at, wetlands such as those in the tropics and sub-tropics, where complex research infrastructure may not exist, or agricultural wetlands located in remote regions, where frequent visits by monitoring scientists prove difficult. In conclusion, the proposed measurement-modelling approach provides guidance on an affordable solution for mitigation and for investigating the consequences of wetland agricultural practice on GHG production, ecological resilience and possible changes to agricultural yields, variety choice and farming practice. (letter)

  18. Estimate of biomass and carbon pools in disturbed and undisturbed oak forests in Tunisia

    Energy Technology Data Exchange (ETDEWEB)

    Zribi, L.; Chaar, H.; Khaldi, A.; Henchi, B.; Mouillot, F.; Gharbi, F.

    2016-07-01

    Aim of the study. To estimate biomass and carbon accumulation in a young and disturbed forest (regenerated after a tornado) and an aged cork oak forest (undisturbed forest) as well as its distribution among the different pools (tree, litter and soil). Area of study. The north west of Tunisia. Material and methods. Carbon stocks were evaluated in the above and belowground cork oak trees, the litter and the 150 cm of the soil. Tree biomass was estimated in both young and aged forests using allometric biomass equations developed for wood stem, cork stem, wood branch, cork branch, leaves, roots and total tree biomass based on combinations of diameter at breast height, total height and crown length as independent variables. Main results. Total tree biomass in forests was 240.58 Mg ha-1 in the young forest and 411.30 Mg ha-1 in the aged forest with a low root/shoot ratio (0.41 for young forest and 0.31 for aged forest). Total stored carbon was 419.46 Mg C ha-1 in the young forest and 658.09 Mg C ha-1 in the aged forest. Carbon stock (Mg C ha-1) was estimated to be113.61(27.08%) and 194.08 (29.49%) in trees, 3.55 (0.85%) and 5.73 (0.87%) in litter and 302.30 (72.07%) and 458.27 (69.64%) in soil in the young and aged forests, respectively. Research highlights. Aged undisturbed forest had the largest tree biomass but a lower potential for accumulation of carbon in the future; in contrast, young disturbed forest had both higher growth and carbon storage potential. (Author)

  19. Partitioning of soil CO2 efflux in un-manipulated and experimentally flooded plots of a temperate fen

    Science.gov (United States)

    Wunderlich, S.; Borken, W.

    2012-08-01

    Peatlands store large amounts of organic carbon, but the carbon stock is sensitive to changes in precipitation or water table manipulations. Restoration of drained peatlands by drain blocking and flooding is a common measure to conserve and augment the carbon stock of peatland soils. Here, we report to what extent flooding affected the contribution of heterotrophic and rhizosphere respiration to soil CO2 efflux in a grass-dominated mountain fen in Germany. Soil CO2 efflux was measured in three un-manipulated control plots and three flooded plots in two consecutive years. Flooding was achieved by permanent irrigation during the growing seasons. Radiocarbon signatures of CO2 from different sources including soil CO2 efflux, incubated peat cores and live grass roots were repeatedly analyzed for partitioning of soil CO2 efflux. Additionally, heterotrophic respiration and its radiocarbon signature were determined by eliminating rhizosphere respiration in trenched subplots (only control). In the control plots, rhizosphere respiration determined by 14C signatures contributed between 47 and 61% during the growing season, but was small (4 ± 8%) immediately before budding. Trenching revealed a smaller rhizosphere contribution of 33 ± 8% (2009) and 22 ± 9% (2010) during growing seasons. Flooding reduced annual soil CO2 efflux of the fen by 42% in 2009 and by 30% in 2010. The reduction was smaller in 2010 mainly through naturally elevated water level in the control plots. A one-week interruption of irrigation caused a strong short-lived increase in soil CO2 efflux, demonstrating the sensitivity of the fen to water table drawdown near the peat surface. The reduction in soil CO2 efflux in the flooded plots diminished the relative proportion of rhizosphere respiration from 56 to 46%, suggesting that rhizosphere respiration was slightly more sensitive to flooding than heterotrophic respiration.

  20. Use of carbon isotopes as tracer to estimate carbon dynamics in forest

    International Nuclear Information System (INIS)

    Atarashi-Andoh, Mariko; Koarashi, Jun; Ishizuka, Shigehiro; Hirai, Keizo

    2010-01-01

    Soil respiration is the sum of heterotrophic respiration (decomposition of soil organic matter and litter) and root respiration. These CO 2 sources may respond differently to the variation in environmental change. Hence, the production of CO 2 from each source needs to be estimated individually. In this study, we use radiocarbon signatures to partition soil respiration in a cool-temperate deciduous forest in Japan by means of an isotope mass balance approach. Monthly measurements of Δ 14 C in soil respiration were conducted using the closed chamber method. The Δ 14 C in root respiration was assumed to be the value equivalent to the present atmospheric CO 2 and the Δ 14 C in heterotrophic respiration was estimated from the depth profile of Δ 14 C in soil organic matter. The results showed the seasonal variation in each source; the contribution of root respiration increased in July, while the contribution of heterotrophic respiration increased with the rise in soil temperature in August. The annual CO 2 flux was calculated using temperature-CO 2 flux model and the hourly soil temperature data in the site. Based on the results, the contribution ratios of CO 2 sources to soil respiration were estimated as: 34% from litter decomposition, 31% from soil organic matter decomposition and 35% from root respiration. (author)

  1. Correlation Lengths for Estimating the Large-Scale Carbon and Heat Content of the Southern Ocean

    Science.gov (United States)

    Mazloff, M. R.; Cornuelle, B. D.; Gille, S. T.; Verdy, A.

    2018-02-01

    The spatial correlation scales of oceanic dissolved inorganic carbon, heat content, and carbon and heat exchanges with the atmosphere are estimated from a realistic numerical simulation of the Southern Ocean. Biases in the model are assessed by comparing the simulated sea surface height and temperature scales to those derived from optimally interpolated satellite measurements. While these products do not resolve all ocean scales, they are representative of the climate scale variability we aim to estimate. Results show that constraining the carbon and heat inventory between 35°S and 70°S on time-scales longer than 90 days requires approximately 100 optimally spaced measurement platforms: approximately one platform every 20° longitude by 6° latitude. Carbon flux has slightly longer zonal scales, and requires a coverage of approximately 30° by 6°. Heat flux has much longer scales, and thus a platform distribution of approximately 90° by 10° would be sufficient. Fluxes, however, have significant subseasonal variability. For all fields, and especially fluxes, sustained measurements in time are required to prevent aliasing of the eddy signals into the longer climate scale signals. Our results imply a minimum of 100 biogeochemical-Argo floats are required to monitor the Southern Ocean carbon and heat content and air-sea exchanges on time-scales longer than 90 days. However, an estimate of formal mapping error using the current Argo array implies that in practice even an array of 600 floats (a nominal float density of about 1 every 7° longitude by 3° latitude) will result in nonnegligible uncertainty in estimating climate signals.

  2. Equivalence of live tree carbon stocks produced by three estimation approaches for forests of the western United States

    Science.gov (United States)

    Coeli M. Hoover; James E. Smith

    2017-01-01

    The focus on forest carbon estimation accompanying the implementation of increased regulatory and reporting requirements is fostering the development of numerous tools and methods to facilitate carbon estimation. One such well-established mechanism is via the Forest Vegetation Simulator (FVS), a growth and yield modeling system used by public and private land managers...

  3. 329 Diversité végétale urbaine et estimation du stock de carbone ...

    African Journals Online (AJOL)

    TOSHIBA

    Diversité végétale urbaine et estimation du stock de carbone : cas de la commune du Plateau ... Urban plants diversity and carbon stock estimation: the case of Plateau district. Abidjan, Côte d'Ivoire ..... [15] - R. HOME; C. KELLER; P. NAGEL; N. BAUER et M. HUNZIKER, Selection criteria for flagship species by conservation ...

  4. Reduced carbon emission estimates from fossil fuel combustion and cement production in China

    OpenAIRE

    Liu, Zhu; Guan, Dabo; Wei, Wei; Davis, Steven J.; Ciais, Philippe; Bai, Jin; Peng, Shushi; Zhang, Qiang; Hubacek, Klaus; Garland, Gregg; Andres, Robert J.; Crawford-Brown, Douglas; Lin, Jintai; Zhao, Hongyan; Hong, Chaopeng

    2015-01-01

    This is the author accepted manuscript. The final version is available from NPG via http://dx.doi.org/10.1038/nature14677 Nearly three-quarters of the growth in global carbon emission from burning of fossil fuels and cement production between 2010 and 2012 occurred in China. Yet estimates of Chinese emissions remain subject to large uncertainty; inventories of China's total fossil fuel carbon emissions in 2008 varied by 0.3 GtC, or 15 per cent. The primary sources of this uncertainty are c...

  5. Estimation of black carbon content for biomass burning aerosols from multi-channel Raman lidar data

    Science.gov (United States)

    Talianu, Camelia; Marmureanu, Luminita; Nicolae, Doina

    2015-04-01

    Biomass burning due to natural processes (forest fires) or anthropical activities (agriculture, thermal power stations, domestic heating) is an important source of aerosols with a high content of carbon components (black carbon and organic carbon). Multi-channel Raman lidars provide information on the spectral dependence of the backscatter and extinction coefficients, embedding information on the black carbon content. Aerosols with a high content of black carbon have large extinction coefficients and small backscatter coefficients (strong absorption), while aerosols with high content of organic carbon have large backscatter coefficients (weak absorption). This paper presents a method based on radiative calculations to estimate the black carbon content of biomass burning aerosols from 3b+2a+1d lidar signals. Data is collected at Magurele, Romania, at the cross-road of air masses coming from Ukraine, Russia and Greece, where burning events are frequent during both cold and hot seasons. Aerosols are transported in the free troposphere, generally in the 2-4 km altitude range, and reaches the lidar location after 2-3 days. Optical data are collected between 2011-2012 by a multi-channel Raman lidar and follows the quality assurance program of EARLINET. Radiative calculations are made with libRadTran, an open source radiative model developed by ESA. Validation of the retrievals is made by comparison to a co-located C-ToF Aerosol Mass Spectrometer. Keywords: Lidar, aerosols, biomass burning, radiative model, black carbon Acknowledgment: This work has been supported by grants of the Romanian National Authority for Scientific Research, Programme for Research- Space Technology and Advanced Research - STAR, project no. 39/2012 - SIAFIM, and by Romanian Partnerships in priority areas PNII implemented with MEN-UEFISCDI support, project no. 309/2014 - MOBBE

  6. Estimating carbon sequestration in the piedmont ecoregion of the United States from 1971 to 2010

    Directory of Open Access Journals (Sweden)

    Jinxun Liu

    2016-06-01

    Full Text Available Abstract Background Human activities have diverse and profound impacts on ecosystem carbon cycles. The Piedmont ecoregion in the eastern United States has undergone significant land use and land cover change in the past few decades. The purpose of this study was to use newly available land use and land cover change data to quantify carbon changes within the ecoregion. Land use and land cover change data (60-m spatial resolution derived from sequential remotely sensed Landsat imagery were used to generate 960-m resolution land cover change maps for the Piedmont ecoregion. These maps were used in the Integrated Biosphere Simulator (IBIS to simulate ecosystem carbon stock and flux changes from 1971 to 2010. Results Results show that land use change, especially urbanization and forest harvest had significant impacts on carbon sources and sinks. From 1971 to 2010, forest ecosystems sequestered 0.25 Mg C ha−1 yr−1, while agricultural ecosystems sequestered 0.03 Mg C ha−1 yr−1. The total ecosystem C stock increased from 2271 Tg C in 1971 to 2402 Tg C in 2010, with an annual average increase of 3.3 Tg C yr−1. Conclusions Terrestrial lands in the Piedmont ecoregion were estimated to be weak net carbon sink during the study period. The major factors contributing to the carbon sink were forest growth and afforestation; the major factors contributing to terrestrial emissions were human induced land cover change, especially urbanization and forest harvest. An additional amount of carbon continues to be stored in harvested wood products. If this pool were included the carbon sink would be stronger.

  7. Estimation of Potential Carbon Dioxide Storage Capacities of Onshore Sedimentary Basins in Republic of Korea

    Science.gov (United States)

    Park, S.; Kim, J.; Lee, Y.

    2010-12-01

    The potential carbon dioxide storage capacities of the five main onshore sedimentary basins (Chungnam, Gyeongsang, Honam, Mungyeong, and Taebaeksan Basins) in Republic of Korea are estimated based on the methods suggested by the United States National Energy Technology Laboratory (NETL). The target geologic formations considered for geologic storage of carbon dioxide in the sedimentary basins are sandstone and coal beds. The density of carbon dioxide is set equal to 446.4 kg/m3. The adsorption capacity and density of coal (anthracite) are set equal to 2.71 × 10-2 kg/kg and 1.82 × 103 kg/m3, respectively. The average storage efficiency factors for sandstone and coal are set equal to 2.5% and 34.0%, respectively. The Chungnam Basin has the sandstone volume of 72 km3 and the coal volume of 1.24 km3. The average porosity of sandstone in the Chungnam Basin is 3.8%. As a result, the potential carbon dioxide storage capacities of sandstone and coal in the Chungnam Basin are estimated to be 31 Mton and 21 Mton, respectively. The Gyeongsang Basin has the sandstone volume of 1,960 km3. The average porosity of sandstone in the Gyeongsang Basin is 4.6%. As a result, the potential carbon dioxide storage capacity of sandstone in the Gyeongsang Basin is estimated to be 1,011 Mton. The Honam Basin has the sandstone volume of 8 km3 and the coal volume of 0.27 km3. The average porosity of sandstone in the Honam Basin is 1.9%. As a result, the potential carbon dioxide storage capacities of sandstone and coal in the Honam Basin are estimated to be 2 Mton and 5 Mton, respectively. The Mungyeong Basin has the sandstone volume of 60 km3 and the coal volume of 0.66 km3. The average porosity of sandstone in the Mungyeong Basin is 2.0%. As a result, the potential carbon dioxide storage capacities of sandstone and coal in the Mungyeong Basin are estimated to be 13 Mton and 11 Mton, respectively. The Taebaeksan Basin has the sandstone volume of 71 km3 and the coal volume of 0.73 km3. The

  8. CO{sub 2}-recycling by plants: how reliable is the carbon isotope estimation?

    Energy Technology Data Exchange (ETDEWEB)

    Siegwolf, R T.W.; Saurer, M [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Koerner, C [Basel Univ., Basel (Switzerland)

    1997-06-01

    In the study of plant carbon relations, the amount of the respiratory losses from the soil was estimated, determining the gradient of the stable isotope {sup 13}C with increasing plant canopy height. According to the literature 8-26% of the CO{sub 2} released in the forests by soil and plant respiratory processes are reassimilated (recycled) by photosynthesis during the day. Our own measurements however, which we conducted in grass land showed diverging results from no indicating of carbon recycling, to a considerable {delta}{sup 13}C gradient suggesting a high carbon recycling rate. The role of other factors, such as air humidity and irradiation which influence the {delta}{sup 13}C in a canopy as well, are discussed. (author) 3 figs., 4 refs.

  9. Carbon dioxide emissions due to Swedish imports and consumption: estimates using different methods

    International Nuclear Information System (INIS)

    Carlsson-Kanyama, Annika; Assefa, Getachew; Wadeskog, Anders

    2007-04-01

    Global trade of products and services challenges the traditional way in which emissions of carbon dioxide are declared and accounted for. Instead of only considering territorial emissions there are now strong reasons to determine how the carbon dioxide emitted in the production of imports are partitioned around the world and how the total emissions change for a country's final consumption compared to final production. In this report results from four different methods of calculating the total carbon dioxide emissions from Sweden's overall consumption are presented. Total carbon dioxide emissions for Sweden's final consumption vary from 57 to 109 M tons during one year depending on the methodology. The four methods used for estimating these emissions give results of 57, 61, 68 and 109 Mton of carbon dioxide. Two methods are based on information concerning Sweden's imports and our national production of goods and services excluding production that is exported while two methods are based on final consumer expenditures. Three of the methods use mainly emission data from Sweden while one method depends entirely upon emission data from Sweden's trading partners. The last method also gives the highest emissions level, 109 Mton of carbon dioxide. The calculations performed here can be compared to the emissions reported by Sweden, 54 Mton of carbon dioxide per year. Our estimates give per capita emission levels of between 6,3 and 12 tons of carbon dioxide per year. The estimate of 12 tons per capita is a result of using emissions data from Sweden's trading partners. The total emissions as a result of Sweden's imports are 26 or 74 M tons of carbon dioxide depending on how they are calculated. The lower figure is based upon the imports of today but with emissions as if everything was produced as in Sweden. The higher level is based upon using existing but partly inadequate international emission statistics. These levels can be compared to the about 35 M tons of carbon dioxide

  10. [Tree above-ground biomass allometries for carbon stocks estimation in the Caribbean mangroves in Colombia].

    Science.gov (United States)

    Yepes, Adriana; Zapata, Mauricio; Bolivar, Jhoanata; Monsalve, Alejandra; Espinosa, Sandra Milena; Sierra-Correa, Paula Cristina; Sierra, Andrés

    2016-06-01

    The distribution of carbon in “Blue Carbon” ecosystems such as mangroves is little known, when compared with the highly known terrestrial forests, despite its particular and recognized high productivity and carbon storage capacity. The objective of this study was to analyze the above ground biomass (AGB) of the species Rhizophora mangle and Avicennia germinans from the Marine Protected Area of Distrito de Manejo Integrado (DMI), Cispatá-Tinajones-La Balsa, Caribbean Colombian coast. With official authorization, we harvested and studied 30 individuals of each species, and built allometric models in order to estimate AGB. Our AGB results indicated that the studied mangrove forests of the DMI Colombian Caribbean was of 129.69 ± 20.24 Mg/ha, equivalent to 64.85 ± 10.12 MgC/ha. The DMI has an area of 8 570.9 ha in mangrove forests, and we estimated that the total carbon potential stored was about 555 795.93 Mg C. The equations generated in this study can be considered as an alternative for the assessment of carbon stocks in AGB of mangrove forests in Colombia; as other available AGB allometric models do not discriminate mangrove forests, despite being particular ecosystems. They can be used for analysis at a more detailed scale and are considered useful to determine the carbon storage potential of mangrove forests, as a country alternative to support forest conservation and emission reduction strategies. In general, the potential of carbon storage from Colombian Caribbean mangrove forests is important and could promote the country leadership of the “blue carbon” stored.

  11. Estimation of fluoride levels in various commercially available carbonated soft drinks in Chandigarh city, India

    Directory of Open Access Journals (Sweden)

    Mohit Bansal

    2015-01-01

    Full Text Available Introduction: Fluoride has a preventive action on dental caries. However, Excessive ingestion of fluoride from different sources can lead to the development of dental fluorosis. Aim: To estimate fluoride levels in various commercially available carbonated soft drinks available in Chandigarh city. Materials and Methods: Twelve different brands of commercially available soft drinks were purchased from three different places and divided into three groups. Fluoride levels were estimated using fluoride test strips Quantofix 37211 Fluka; Sigma-Aldrich. Results: Fluoride levels ranged from 0.12 to 0.42 mg/dl F with the maximum level in Thumbs up and least in Diet Pepsi. Conclusion: The levels of fluoride varied in various carbonated soft drinks analyzed. This could contribute significantly to the total fluoride intake from all sources and thus be an important risk factor for the development of dental fluorosis.

  12. A new evaluation of the uncertainty associated with CDIAC estimates of fossil fuel carbon dioxide emission

    Directory of Open Access Journals (Sweden)

    Robert J. Andres

    2014-07-01

    Full Text Available Three uncertainty assessments associated with the global total of carbon dioxide emitted from fossil fuel use and cement production are presented. Each assessment has its own strengths and weaknesses and none give a full uncertainty assessment of the emission estimates. This approach grew out of the lack of independent measurements at the spatial and temporal scales of interest. Issues of dependent and independent data are considered as well as the temporal and spatial relationships of the data. The result is a multifaceted examination of the uncertainty associated with fossil fuel carbon dioxide emission estimates. The three assessments collectively give a range that spans from 1.0 to 13% (2 σ. Greatly simplifying the assessments give a global fossil fuel carbon dioxide uncertainty value of 8.4% (2 σ. In the largest context presented, the determination of fossil fuel emission uncertainty is important for a better understanding of the global carbon cycle and its implications for the physical, economic and political world.

  13. Estimating Aboveground Biomass and Carbon Stocks in Periurban Andean Secondary Forests Using Very High Resolution Imagery

    Directory of Open Access Journals (Sweden)

    Nicola Clerici

    2016-07-01

    Full Text Available Periurban forests are key to offsetting anthropogenic carbon emissions, but they are under constant threat from urbanization. In particular, secondary Neotropical forest types in Andean periurban areas have a high potential to store carbon, but are currently poorly characterized. To address this lack of information, we developed a method to estimate periurban aboveground biomass (AGB—a proxy for multiple ecosystem services—of secondary Andean forests near Bogotá, Colombia, based on very high resolution (VHR GeoEye-1, Pleiades-1A imagery and field-measured plot data. Specifically, we tested a series of different pre-processing workflows to derive six vegetation indices that were regressed against in situ estimates of AGB. Overall, the coupling of linear models and the Ratio Vegetation Index produced the most satisfactory results. Atmospheric and topographic correction proved to be key in improving model fit, especially in high aerosol and rugged terrain such as the Andes. Methods and findings provide baseline AGB and carbon stock information for little studied periurban Andean secondary forests. The methodological approach can also be used for integrating limited forest monitoring plot AGB data with very high resolution imagery for cost-effective modelling of ecosystem service provision from forests, monitoring reforestation and forest cover change, and for carbon offset assessments.

  14. Ecological Variability and Carbon Stock Estimates of Mangrove Ecosystems in Northwestern Madagascar

    Directory of Open Access Journals (Sweden)

    Trevor G. Jones

    2014-01-01

    Full Text Available Mangroves are found throughout the tropics, providing critical ecosystem goods and services to coastal communities and supporting rich biodiversity. Despite their value, world-wide, mangroves are being rapidly degraded and deforested. Madagascar contains approximately 2% of the world’s mangroves, >20% of which has been deforested since 1990 from increased extraction for charcoal and timber and conversion to small to large-scale agriculture and aquaculture. Loss is particularly prominent in the northwestern Ambaro and Ambanja bays. Here, we focus on Ambaro and Ambanja bays, presenting dynamics calculated using United States Geological Survey (USGS national-level mangrove maps and the first localized satellite imagery derived map of dominant land-cover types. The analysis of USGS data indicated a loss of 7659 ha (23.7% and a gain of 995 ha (3.1% from 1990–2010. Contemporary mapping results were 93.4% accurate overall (Kappa 0.9, with producer’s and user’s accuracies ≥85%. Classification results allowed partitioning mangroves in to ecologically meaningful, spectrally distinct strata, wherein field measurements facilitated estimating the first total carbon stocks for mangroves in Madagascar. Estimates suggest that higher stature closed-canopy mangroves have average total vegetation carbon values of 146.8 Mg/ha (±10.2 and soil organic carbon of 446.2 (±36.9, supporting a growing body of studies that mangroves are amongst the most carbon-dense tropical forests.

  15. Sustained effects of atmospheric [CO2] and nitrogen availability on forest soil CO2 efflux.

    Science.gov (United States)

    Oishi, A Christopher; Palmroth, Sari; Johnsen, Kurt H; McCarthy, Heather R; Oren, Ram

    2014-04-01

    Soil CO2 efflux (Fsoil ) is the largest source of carbon from forests and reflects primary productivity as well as how carbon is allocated within forest ecosystems. Through early stages of stand development, both elevated [CO2] and availability of soil nitrogen (N; sum of mineralization, deposition, and fixation) have been shown to increase gross primary productivity, but the long-term effects of these factors on Fsoil are less clear. Expanding on previous studies at the Duke Free-Air CO2 Enrichment (FACE) site, we quantified the effects of elevated [CO2] and N fertilization on Fsoil using daily measurements from automated chambers over 10 years. Consistent with previous results, compared to ambient unfertilized plots, annual Fsoil increased under elevated [CO2] (ca. 17%) and decreased with N (ca. 21%). N fertilization under elevated [CO2] reduced Fsoil to values similar to untreated plots. Over the study period, base respiration rates increased with leaf productivity, but declined after productivity saturated. Despite treatment-induced differences in aboveground biomass, soil temperature and water content were similar among treatments. Interannually, low soil water content decreased annual Fsoil from potential values - estimated based on temperature alone assuming nonlimiting soil water content - by ca. 0.7% per 1.0% reduction in relative extractable water. This effect was only slightly ameliorated by elevated [CO2]. Variability in soil N availability among plots accounted for the spatial variability in Fsoil , showing a decrease of ca. 114 g C m(-2) yr(-1) per 1 g m(-2) increase in soil N availability, with consistently higher Fsoil in elevated [CO2] plots ca. 127 g C per 100 ppm [CO2] over the +200 ppm enrichment. Altogether, reflecting increased belowground carbon partitioning in response to greater plant nutritional needs, the effects of elevated [CO2] and N fertilization on Fsoil in this stand are sustained beyond the early stages of stand development and

  16. Quantifying the uncertainty of regional and national estimates of soil carbon stocks

    Science.gov (United States)

    Papritz, Andreas

    2013-04-01

    At regional and national scales, carbon (C) stocks are frequently estimated by means of regression models. Such statistical models link measurements of carbons stocks, recorded for a set of soil profiles or soil cores, to covariates that characterize soil formation conditions and land management. A prerequisite is that these covariates are available for any location within a region of interest G because they are used along with the fitted regression coefficients to predict the carbon stocks at the nodes of a fine-meshed grid that is laid over G. The mean C stock in G is then estimated by the arithmetic mean of the stock predictions for the grid nodes. Apart from the mean stock, the precision of the estimate is often also of interest, for example to judge whether the mean C stock has changed significantly between two inventories. The standard error of the estimated mean stock in G can be computed from the regression results as well. Two issues are thereby important: (i) How large is the area of G relative to the support of the measurements? (ii) Are the residuals of the regression model spatially auto-correlated or is the assumption of statistical independence tenable? Both issues are correctly handled if one adopts a geostatistical block kriging approach for estimating the mean C stock within a region and its standard error. In the presentation I shall summarize the main ideas of external drift block kriging. To compute the standard error of the mean stock, one has in principle to sum the elements a potentially very large covariance matrix of point prediction errors, but I shall show that the required term can be approximated very well by Monte Carlo techniques. I shall further illustrated with a few examples how the standard error of the mean stock estimate changes with the size of G and with the strenght of the auto-correlation of the regression residuals. As an application a robust variant of block kriging is used to quantify the mean carbon stock stored in the

  17. Estimating rainforest biomass stocks and carbon loss from deforestation and degradation in Papua New Guinea 1972-2002: Best estimates, uncertainties and research needs.

    Science.gov (United States)

    Bryan, Jane; Shearman, Phil; Ash, Julian; Kirkpatrick, J B

    2010-01-01

    Reduction of carbon emissions from tropical deforestation and forest degradation is being considered a cost-effective way of mitigating the impacts of global warming. If such reductions are to be implemented, accurate and repeatable measurements of forest cover change and biomass will be required. In Papua New Guinea (PNG), which has one of the world's largest remaining areas of tropical forest, we used the best available data to estimate rainforest carbon stocks, and emissions from deforestation and degradation. We collated all available PNG field measurements which could be used to estimate carbon stocks in logged and unlogged forest. We extrapolated these plot-level estimates across the forested landscape using high-resolution forest mapping. We found the best estimate of forest carbon stocks contained in logged and unlogged forest in 2002 to be 4770 Mt (+/-13%). Our best estimate of gross forest carbon released through deforestation and degradation between 1972 and 2002 was 1178 Mt (+/-18%). By applying a long-term forest change model, we estimated that the carbon loss resulting from deforestation and degradation in 2001 was 53 Mt (+/-18%), rising from 24 Mt (+/-15%) in 1972. Forty-one percent of 2001 emissions resulted from logging, rising from 21% in 1972. Reducing emissions from logging is therefore a priority for PNG. The large uncertainty in our estimates of carbon stocks and fluxes is primarily due to the dearth of field measurements in both logged and unlogged forest, and the lack of PNG logging damage studies. Research priorities for PNG to increase the accuracy of forest carbon stock assessments are the collection of field measurements in unlogged forest and more spatially explicit logging damage studies. Copyright 2009 Elsevier Ltd. All rights reserved.

  18. Potent and selective mediators of cholesterol efflux

    Energy Technology Data Exchange (ETDEWEB)

    Bielicki, John K; Johansson, Jan

    2015-03-24

    The present invention provides a family of non-naturally occurring polypeptides having cholesterol efflux activity that parallels that of full-length apolipoproteins (e.g., Apo AI and Apo E), and having high selectivity for ABAC1 that parallels that of full-length apolipoproteins. The invention also provides compositions comprising such polypeptides, methods of identifying, screening and synthesizing such polypeptides, and methods of treating, preventing or diagnosing diseases and disorders associated with dyslipidemia, hypercholesterolemia and inflammation.

  19. Efflux inhibitor suppresses Streptococcus mutans virulence properties.

    Science.gov (United States)

    Zeng, Huihui; Liu, Jia; Ling, Junqi

    2017-04-01

    It is well established that efflux pumps play important roles in bacterial pathogenicity and efflux inhibitors (EIs) have been proved to be effective in suppressing bacterial virulence properties. However, little is known regarding the EI of Streptococcus mutans, a well-known caries-inducing bacterium. In this study, we identified the EI of S. mutans through ethidium bromide efflux assay and investigated how EI affected S. mutans virulence regarding the cariogenicity and stress response. Results indicated that reserpine, the identified EI, suppressed acid tolerance, mutacin production and transformation efficiency of S. mutans, and modified biofilm architecture and extracellular polysaccharide distribution. Suppressed glycosyltransferase activity was also noted after reserpine exposure. The data from quantitative real-time-PCR demonstrated that reserpine significantly altered the expression profile of quorum-sensing and virulence-associated genes. These findings suggest that reserpine represents a promising adjunct anticariogenic agent in that it suppresses virulence properties of S. mutans. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  20. Long term estimation of carbon dynamic and sequestration for Iranian agro-ecosystem: I- Net primary productivity and annual carbon input for common agricultural crops

    Directory of Open Access Journals (Sweden)

    M Nassiri Mahalati

    2016-05-01

    Full Text Available Evaluation of carbon input is one of the most important factors for estimating soil carbon changes and potential for carbon sequestration. To evaluate the net primary productivity (NPP and soil carbon input in agricultural eco-systems of Iran, data for yield, cultivated area, harvest index (HI and shoot /root ratio in different crops including: wheat, barley, maize, cotton, rice, alfalfa and chickpea were obtained for different provinces. Then, allocated carbon to different organs of plant were calculated based on carbon allocation coefficients and finally, the net primary productivity based on carbon (NPPc was calculated. The ratio of NPPc that was annually returned to soil was considered as carbon annual input. The results showed that the maximum amount of NPPc for wheat, barely and alfalfa were obtained in Khazari climate for rice, chickpea and cotton was achieved in warm-wet climate and for maize was gained in warm-dry climate. In all regions of Iran, chickpea had the lowest effect on NPPc and consequently on carbon sequestration. The highest amount of carbon input per unit area among studied crops and different regions were observed in Khazari region for alfalfa whereas, the lowest carbon input per unit area was relation to chickpea in cold region. The lowest gap between actual and potential of carbon sequestration was observed in alfalfa whereas wheat, rice and cotton showed the most gap by 0.4, 0.38 and 0.37, respectively.

  1. Impact of heme oxygenase-1 on cholesterol synthesis, cholesterol efflux and oxysterol formation in cultured astroglia.

    Science.gov (United States)

    Hascalovici, Jacob R; Song, Wei; Vaya, Jacob; Khatib, Soliman; Fuhrman, Bianca; Aviram, Michael; Schipper, Hyman M

    2009-01-01

    Up-regulation of heme oxygenase-1 (HO-1) and altered cholesterol (CH) metabolism are characteristic of Alzheimer-diseased neural tissues. The liver X receptor (LXR) is a molecular sensor of CH homeostasis. In the current study, we determined the effects of HO-1 over-expression and its byproducts iron (Fe(2+)), carbon monoxide (CO) and bilirubin on CH biosynthesis, CH efflux and oxysterol formation in cultured astroglia. HO-1/LXR interactions were also investigated in the context of CH efflux. hHO-1 over-expression for 3 days ( approximately 2-3-fold increase) resulted in a 30% increase in CH biosynthesis and a two-fold rise in CH efflux. Both effects were abrogated by the competitive HO inhibitor, tin mesoporphyrin. CO, released from administered CORM-3, significantly enhanced CH biosynthesis; a combination of CO and iron stimulated CH efflux. Free iron increased oxysterol formation three-fold. Co-treatment with LXR antagonists implicated LXR activation in the modulation of CH homeostasis by heme degradation products. In Alzheimer's disease and other neuropathological states, glial HO-1 induction may transduce ambient noxious stimuli (e.g. beta-amyloid) into altered patterns of glial CH homeostasis. As the latter may impact synaptic plasticity and neuronal repair, modulation of glial HO-1 expression (by pharmacological or other means) may confer neuroprotection in patients with degenerative brain disorders.

  2. Estimation of local concentration from measurements of stochastic adsorption dynamics using carbon nanotube-based sensors

    International Nuclear Information System (INIS)

    Jang, Hong; Lee, Jay H.; Braatz, Richard D.

    2016-01-01

    This paper proposes a maximum likelihood estimation (MLE) method for estimating time varying local concentration of the target molecule proximate to the sensor from the time profile of monomolecular adsorption and desorption on the surface of the sensor at nanoscale. Recently, several carbon nanotube sensors have been developed that can selectively detect target molecules at a trace concentration level. These sensors use light intensity changes mediated by adsorption or desorption phenomena on their surfaces. The molecular events occurring at trace concentration levels are inherently stochastic, posing a challenge for optimal estimation. The stochastic behavior is modeled by the chemical master equation (CME), composed of a set of ordinary differential equations describing the time evolution of probabilities for the possible adsorption states. Given the significant stochastic nature of the underlying phenomena, rigorous stochastic estimation based on the CME should lead to an improved accuracy over than deterministic estimation formulated based on the continuum model. Motivated by this expectation, we formulate the MLE based on an analytical solution of the relevant CME, both for the constant and the time-varying local concentrations, with the objective of estimating the analyte concentration field in real time from the adsorption readings of the sensor array. The performances of the MLE and the deterministic least squares are compared using data generated by kinetic Monte Carlo (KMC) simulations of the stochastic process. Some future challenges are described for estimating and controlling the concentration field in a distributed domain using the sensor technology.

  3. Relation of whole blood carboxyhemoglobin concentration to ambient carbon monoxide exposure estimated using regression.

    Science.gov (United States)

    Rudra, Carole B; Williams, Michelle A; Sheppard, Lianne; Koenig, Jane Q; Schiff, Melissa A; Frederick, Ihunnaya O; Dills, Russell

    2010-04-15

    Exposure to carbon monoxide (CO) and other ambient air pollutants is associated with adverse pregnancy outcomes. While there are several methods of estimating CO exposure, few have been evaluated against exposure biomarkers. The authors examined the relation between estimated CO exposure and blood carboxyhemoglobin concentration in 708 pregnant western Washington State women (1996-2004). Carboxyhemoglobin was measured in whole blood drawn around 13 weeks' gestation. CO exposure during the month of blood draw was estimated using a regression model containing predictor terms for year, month, street and population densities, and distance to the nearest major road. Year and month were the strongest predictors. Carboxyhemoglobin level was correlated with estimated CO exposure (rho = 0.22, 95% confidence interval (CI): 0.15, 0.29). After adjustment for covariates, each 10% increase in estimated exposure was associated with a 1.12% increase in median carboxyhemoglobin level (95% CI: 0.54, 1.69). This association remained after exclusion of 286 women who reported smoking or being exposed to secondhand smoke (rho = 0.24). In this subgroup, the median carboxyhemoglobin concentration increased 1.29% (95% CI: 0.67, 1.91) for each 10% increase in CO exposure. Monthly estimated CO exposure was moderately correlated with an exposure biomarker. These results support the validity of this regression model for estimating ambient CO exposures in this population and geographic setting.

  4. Potential carbon sequestration of European arable soils estimated by modelling a comprehensive set of management practices.

    Science.gov (United States)

    Lugato, Emanuele; Bampa, Francesca; Panagos, Panos; Montanarella, Luca; Jones, Arwyn

    2014-11-01

    Bottom-up estimates from long-term field experiments and modelling are the most commonly used approaches to estimate the carbon (C) sequestration potential of the agricultural sector. However, when data are required at European level, important margins of uncertainty still exist due to the representativeness of local data at large scale or different assumptions and information utilized for running models. In this context, a pan-European (EU + Serbia, Bosnia and Herzegovina, Montenegro, Albania, Former Yugoslav Republic of Macedonia and Norway) simulation platform with high spatial resolution and harmonized data sets was developed to provide consistent scenarios in support of possible carbon sequestration policies. Using the CENTURY agroecosystem model, six alternative management practices (AMP) scenarios were assessed as alternatives to the business as usual situation (BAU). These consisted of the conversion of arable land to grassland (and vice versa), straw incorporation, reduced tillage, straw incorporation combined with reduced tillage, ley cropping system and cover crops. The conversion into grassland showed the highest soil organic carbon (SOC) sequestration rates, ranging between 0.4 and 0.8 t C ha(-1)  yr(-1) , while the opposite extreme scenario (100% of grassland conversion into arable) gave cumulated losses of up to 2 Gt of C by 2100. Among the other practices, ley cropping systems and cover crops gave better performances than straw incorporation and reduced tillage. The allocation of 12 to 28% of the European arable land to different AMP combinations resulted in a potential SOC sequestration of 101-336 Mt CO2 eq. by 2020 and 549-2141 Mt CO2 eq. by 2100. Modelled carbon sequestration rates compared with values from an ad hoc meta-analysis confirmed the robustness of these estimates. © 2014 John Wiley & Sons Ltd.

  5. 22Na and 86Rb effluxes from bull spermatozoa

    International Nuclear Information System (INIS)

    Petzoldt, R.; Steffens, T.; Bernhardt, I.

    1986-01-01

    Active transport of sodium and potassium has been postulated for bull sperms by various authors. In the present paper the sodium and rubidium efflux was determined by tracer kinetics. For uninhibited sodium and rubidium efflux a rate constant of 8.9 +- 2.13/min and 13.9 +- 3.89 min, respectively, was found for a bull sperm suspension (20 vol.%, 310 K). After ouabain treatment (0.1 mM), a reduction of the rate constant of sodium efflux to 5.1 +- 1.06/min was found. After cryopreserving (pelletizing process) the majority of samples investigated did not exhibit any inhibition of sodium and rubidium efflux as compared with fresh bull sperms. The inhibition of sodium efflux observed in some cases corresponds to the reduction of the rate constant of sodium efflux caused by ouabain. At storage in seminal plasma (24 h, 278 K) the rate constant of sodium efflux is reduced to 2.7 +- 0.25/min. Both after ouabain treatment and after cryopreserving of sperms having a reduced rate constant the motility of bull sperms is reduced. It is concluded from the results that in bull sperms there exists an ouabain-sensitive sodium efflux, the inhibition of which reduces the rate constant of sodium efflux by 42%. The ouabain-sensitive sodium efflux is related to the motility of the bull sperm cell. (author)

  6. Synergy between Printex nano-carbons and silver nanoparticles for sensitive estimation of antioxidant activity

    International Nuclear Information System (INIS)

    Raymundo-Pereira, Paulo A.; Campos, Anderson M.; Prado, Thiago M.; Furini, Leonardo N.; Boas, Naiza V.; Calegaro, Marcelo L.; Machado, Sergio A.S.

    2016-01-01

    We report on the synthesis, characterization and applications of a Printex L6 carbon-silver hybrid nanomaterial (PC-Ag), which was obtained using a polyol method. In addition, we also highlight the use of Printex L6 nano-carbon as a much cheaper alternative to the use of carbon nanotubes and graphene. The silver nanoparticles (AgNP) were prepared directly on the surface of the Printex 6L carbon “nanocarbon” material using ethylene glycol as the reducing agent. The hybrid nanomaterial was characterized by High-angle annular dark-field transmission electron microscopy (HAADF-TEM), energy–dispersive X-ray spectroscopy (EDX), selected area electron diffraction (SAED), Raman spectroscopy and cyclic voltammetry. Optimized electrocatalytic activity on glassy carbon electrode was reached for the architecture GC/PC-Ag, the silver nanoparticles with size ranging between 1 and 2 nm were well–distributed throughout the hybrid material. The synergy between PC nano-carbons and AgNPs was verified by detection of gallic acid (GA) at a low applied potential (0.091 V vs. Ag/AgCl). GA detection was performed in a concentration range between 5.0 × 10"−"7 and 8.5 × 10"−"6 mol L"−"1, with a detection limit of 6.63 × 10"−"8 mol L"−"1 (66.3 nmol L"−"1), which is considerably lower than similar devices. The approach for fabricating the reproducible GC/PC-Ag electrodes is entirely generic and may be explored for other types of (bio)sensors and devices. - Highlights: • We highlight the use of Printex L6 nano-carbon as a much cheaper alternative to carbon nanotubes and graphene. • The hybrid nanomaterial was completely characterized by MET, EDX, SAED, DRX, RAMAN and cyclic voltammetry. • The silver nanoparticles (size range 1-2 nm) were prepared directly onto the surface of the Printex 6L Carbon “nanocarbon”. • An ultrathin film PC-AgNP nanostructured showed a synergetic effect between PC nanocarbons and AgNP. • Sensitive estimation of

  7. Synergy between Printex nano-carbons and silver nanoparticles for sensitive estimation of antioxidant activity

    Energy Technology Data Exchange (ETDEWEB)

    Raymundo-Pereira, Paulo A., E-mail: pauloaugustoraymundopereira@gmail.com [Instituto de Química de São Carlos, Universidade de São Paulo, São Carlos, São Paulo, CEP 13566-590 (Brazil); Campos, Anderson M.; Prado, Thiago M. [Instituto de Química de São Carlos, Universidade de São Paulo, São Carlos, São Paulo, CEP 13566-590 (Brazil); Furini, Leonardo N. [Faculdade de Ciências e Tecnologia, UNESP Univ Estadual Paulista, 19060-900 Presidente Prudente, São Paulo (Brazil); Boas, Naiza V.; Calegaro, Marcelo L.; Machado, Sergio A.S. [Instituto de Química de São Carlos, Universidade de São Paulo, São Carlos, São Paulo, CEP 13566-590 (Brazil)

    2016-07-05

    We report on the synthesis, characterization and applications of a Printex L6 carbon-silver hybrid nanomaterial (PC-Ag), which was obtained using a polyol method. In addition, we also highlight the use of Printex L6 nano-carbon as a much cheaper alternative to the use of carbon nanotubes and graphene. The silver nanoparticles (AgNP) were prepared directly on the surface of the Printex 6L carbon “nanocarbon” material using ethylene glycol as the reducing agent. The hybrid nanomaterial was characterized by High-angle annular dark-field transmission electron microscopy (HAADF-TEM), energy–dispersive X-ray spectroscopy (EDX), selected area electron diffraction (SAED), Raman spectroscopy and cyclic voltammetry. Optimized electrocatalytic activity on glassy carbon electrode was reached for the architecture GC/PC-Ag, the silver nanoparticles with size ranging between 1 and 2 nm were well–distributed throughout the hybrid material. The synergy between PC nano-carbons and AgNPs was verified by detection of gallic acid (GA) at a low applied potential (0.091 V vs. Ag/AgCl). GA detection was performed in a concentration range between 5.0 × 10{sup −7} and 8.5 × 10{sup −6} mol L{sup −1}, with a detection limit of 6.63 × 10{sup −8} mol L{sup −1} (66.3 nmol L{sup −1}), which is considerably lower than similar devices. The approach for fabricating the reproducible GC/PC-Ag electrodes is entirely generic and may be explored for other types of (bio)sensors and devices. - Highlights: • We highlight the use of Printex L6 nano-carbon as a much cheaper alternative to carbon nanotubes and graphene. • The hybrid nanomaterial was completely characterized by MET, EDX, SAED, DRX, RAMAN and cyclic voltammetry. • The silver nanoparticles (size range 1-2 nm) were prepared directly onto the surface of the Printex 6L Carbon “nanocarbon”. • An ultrathin film PC-AgNP nanostructured showed a synergetic effect between PC nanocarbons and AgNP.

  8. Integration of ground and satellite data to estimate the forest carbon fluxes of a Mediterranean region

    Science.gov (United States)

    Chiesi, M.; Maselli, F.; Moriondo, M.; Fibbi, L.; Bindi, M.; Running, S. W.

    2009-04-01

    The current paper reports on the development and testing of a methodology capable of simulating the main terms of forest carbon budget (gross primary production, GPP, net primary production, NPP, and net ecosystem exchange, NEE) in the Mediterranean environment. The study area is Tuscany, a region of Central Italy which is covered by forests over about half of its surface. It is peculiar for its extremely heterogeneous morphological and climatic features which ranges from typically Mediterranean to temperate warm or cool according to the altitudinal and latitudinal gradients and the distance from the sea (Rapetti and Vittorini, 1995). The simulation of forest carbon budget is based on the preliminary collection of several data layers to characterize the eco-climatic and forest features of the region (i.e. maps of forest type and volume, daily meteorological data and monthly NDVI-derived FAPAR - fraction of absorbed photosynthetically active radiation - estimates for the years 1999-2003). In particular, the 1:250.000 forest type map describes the distribution of 18 forest classes and was obtained by the Regional Cartographic Service. The volume map, with a 30 m spatial resolution and a mean accuracy of about 90 m3/ha, was produced by combining the available regional forest inventory data and Landsat TM images (Maselli and Chiesi, 2006). Daily meteorological data (minimum and maximum air temperatures and precipitation) were extrapolated by the use of the DAYMET algorithm (Thornton et al., 1997) from measurements taken at existing whether stations for the years 1996-2003 (calibration plus application periods); solar radiation was then estimated by the model MT-CLIM (Thornton et al., 2000). Monthly NDVI-derived FAPAR estimates were obtained using the Spot-VEGETATION satellite sensor data for the whole study period (1999-2003). After the collection of these data layers, a simplified, remote sensing based parametric model (C-Fix), is applied for the production of a

  9. A modelling approach to estimate carbon emissions from D.R.C. deforestation

    Science.gov (United States)

    Najdovski, Nicolas; Poulter, Benjamin; Defourny, Pierre; Moreau, Inès; Maignan, Fabienne; Ciais, Philippe; Verhegghen, Astrid; Kibambe Lubamba, Jean-Paul; Jungers, Quentin; De Weirdt, Marjolein; Verbeeck, Hans; MacBean, Natasha; Peylin, Philippe

    2014-05-01

    With its 1.8 million squared kilometres, the Congo basin dense forest represents the second largest contiguous forest of the world. These extensive forest ecosystems play a significant role in the regulation of global climate by their potential carbon dioxide emissions and carbon storage. Under a stable climate, the vegetation, assumed to be at the equilibrium, is known to present neutral emissions over a year with seasonal variations. However, modifications in temperatures, precipitations, CO2 atmospheric concentrations have the potential to modify this balance leading to higher or lower biomass storage. In addition, deforestation and forest degradation have played a significant role over the past several decades and are expected to become increasingly important in the future. Here, we quantify the relative effects of deforestation and 21st century climate change on carbon emissions in Congo Basin over the next three decades (2005-2035). Carbon dioxide emissions are estimated using a series of moderate resolution (10 km) vegetation maps merged with spatially explicit deforestation projections and developed to work with a prognostic carbon cycle model. The inversion of the deforestation model allowed hindcast land-use patterns back to 1800 by using land cover change rates based on the HYDE database. Simulations were made over the Democratic Republic of Congo (DRC) using the ORCHIDEE dynamic global vegetation model with climate forcing from the CMIP5 Representative Concentration Pathway 8.5 scenario for the HadGEM2. Two simulations were made, a reference simulation with land cover fixed at 2005 and a land cover change simulation with changing climate and CO2, to quantify the net land cover change emissions and climate emissions directly. Because of the relatively high resolution of the model simulations, the spatial patterns of human-driven carbon losses can be tracked in the context of climate change, providing information for mitigation and vulnerability

  10. A Greenhouse Gas and Soil Carbon Model for Estimating the Carbon Footprint of Livestock Production in Canada

    Directory of Open Access Journals (Sweden)

    Brian G. McConkey

    2012-09-01

    Full Text Available To assess tradeoffs between environmental sustainability and changes in food production on agricultural land in Canada the Unified Livestock Industry and Crop Emissions Estimation System (ULICEES was developed. It incorporates four livestock specific GHG assessments in a single model. To demonstrate the application of ULICEES, 10% of beef cattle protein production was assumed to be displaced with an equivalent amount of pork protein. Without accounting for the loss of soil carbon, this 10% shift reduced GHG emissions by 2.5 TgCO2e y−1. The payback period was defined as the number of years required for a GHG reduction to equal soil carbon lost from the associated land use shift. A payback period that is shorter than 40 years represents a net long term decrease in GHG emissions. Displacing beef cattle with hogs resulted in a surplus area of forage. When this residual land was left in ungrazed perennial forage, the payback periods were less than 4 years and when it was reseeded to annual crops, they were equal to or less than 40 years. They were generally greater than 40 years when this land was used to raise cattle. Agricultural GHG mitigation policies will inevitably involve a trade-off between production, land use and GHG emission reduction. ULICEES is a model that can objectively assess these trade-offs for Canadian agriculture.

  11. The Dynamics, Ecological Variability and Estimated Carbon Stocks of Mangroves in Mahajamba Bay, Madagascar

    Directory of Open Access Journals (Sweden)

    Trevor G. Jones

    2015-08-01

    Full Text Available Mangroves are found throughout the tropics, providing critical ecosystem goods and services to coastal communities and supporting rich biodiversity. Globally, mangroves are being rapidly degraded and deforested at rates exceeding loss in many tropical inland forests. Madagascar contains around 2% of the global distribution, >20% of which has been deforested since 1990, primarily from over-harvest for forest products and conversion for agriculture and aquaculture. While historically not prominent, mangrove loss in Madagascar’s Mahajamba Bay is increasing. Here, we focus on Mahajamba Bay, presenting long-term dynamics calculated using United States Geological Survey (USGS national-level mangrove maps contextualized with socio-economic research and ground observations, and the results of contemporary (circa 2011 mapping of dominant mangrove types. The analysis of the USGS data indicated 1050 hectares (3.8% lost from 2000 to 2010, which socio-economic research suggests is increasingly driven by commercial timber extraction. Contemporary mapping results permitted stratified sampling based on spectrally distinct and ecologically meaningful mangrove types, allowing for the first-ever vegetation carbon stock estimates for Mahajamba Bay. The overall mean carbon stock across all mangrove classes was estimated to be 100.97 ± 10.49 Mg C ha−1. High stature closed-canopy mangroves had the highest average carbon stock estimate (i.e., 166.82 ± 15.28 Mg C ha−1. These estimates are comparable to other published values in Madagascar and elsewhere in the Western Indian Ocean and demonstrate the ecological variability of Mahajamba Bay’s mangroves and their value towards climate change mitigation.

  12. Effect of measurement time of the day on the relationship between temperature and soil CO2 Efflux

    Czech Academy of Sciences Publication Activity Database

    Dařenová, Eva; Pavelka, Marian; Janouš, Dalibor

    2011-01-01

    Roč. 59, č. 6 (2011), s. 127-133 ISSN 1211-8516 R&D Projects: GA MŽP(CZ) SP/2D1/70/08 Institutional research plan: CEZ:AV0Z60870520 Keywords : soil CO2 efflux * R10 * Q10 * Picea abies * seasonal carbon flux Subject RIV: EH - Ecology, Behaviour

  13. Greenhouse gas efflux from an impacted Malaysian tropical peat swamp (Invited)

    Science.gov (United States)

    Waldron, S.; Vihermaa, L. E.; Evers, S.; Garnett, M.; Newton, J.; Padfield, R.

    2013-12-01

    Tropical peatlands constitute ~11% of global peatland area and ~12% of the global peat C pool. Malaysia alone contains 10% of tropical peats. Due to rising global demands for food and biofuels, SE-Asia peat swamp forest ecosystems are threatened by increasing amounts of drainage, fire and conversion to plantation. These processes can change the GHG emissions and thus net ecosystem C balance. However, in comparison to temperate and boreal peatlands, there is a lack of data on terrestrial-aquatic-atmospheric carbon transfer from tropical peatlands, both those that are little disturbed and those facing anthropogenic pressures. Lateral transport of soil-respired carbon, and fluvial respiration or UV-oxidation of terrestrial DOC primes atmospheric carbon dioxide efflux. We now know that DOC lost from disturbed tropical peat swamp forests can be centuries to millennia old and originates deep within the peat column - this carbon may fuel efflux of old carbon dioxide and so anthropogenic land-use change renders the older, slower carbon cycles shorter and faster. Currently we have no knowledge of how significant ';older-slower' terrestrial-aquatic-atmospheric cycles are in disturbed tropical peatlands. Further, in some areas for commercial reasons, or by conservation bodies trying to minimise peat habitat loss, logged peats have been left to regenerate. Consequently, unpicking the legacy of multiple land uses on magnitude, age and source of GHG emissions is challenging but required to support land management decisions and projections of response to a changing climate. Here, we present the results of our first field campaign in July 2013 to the Raja Musa and Sungai Karang Peat Swamp Forest Reserves in North Selangor, Malaysia. This is one of Malaysia's largest oceanic peat swamps, and has been selectively logged and drained for 80 years, but is now subject to a 30 year logging ban to aid forest regeneration and build up wood stocks. From sites subject to different land use

  14. Determination of the carbon content of domestic farm produces to estimate offsite C-14 ingestion dose

    International Nuclear Information System (INIS)

    Jung, Y. G.; Kim, M. J.; Lee, G. B.

    2003-01-01

    The carbon content of grains, leafy and root vegetables, and fruits which the Koreans usually eat were calculated to use in the estimation of offsite C-14 ingestion dose. With the data of food intake per day in the Report on 1998 national health and nutrition survey- dietary intake survey, 5 age-group integrate d intake of the 4 farm produce groups were extracted for food items and the amount. Intake percentage in each food group were taken as food weighing factor for the foods. Carbon content was calculated using protein, fat, and carbohydrate content of the foods, and multiplied by the corresponding food weighing factor to derive the content of the food groups. The calculated carbon content of grains, leafy and root vegetables, and fruits were 39.%, 4.2%, 8.0%, and 5.9% respectively. Grains and fruits were not much different from ODCM for carbon content, but vegetables were higher by 0.7%∼4.5%

  15. Attempts at estimating mixed venous carbon dioxide tension by the single-breath method.

    Science.gov (United States)

    Ohta, H; Takatani, O; Matsuoka, T

    1989-01-01

    The single-breath method was originally proposed by Kim et al. [1] for estimating the blood carbon dioxide tension and cardiac output. Its reliability has not been proven. The present study was undertaken, using dogs, to compare the mixed venous carbon dioxide tension (PVCO2) calculated by the single-breath method with the PVCO2 measured in mixed venous blood, and to evaluate the influence of variations in the exhalation duration and the volume of expired air usually discarded from computations as the deadspace. Among the exhalation durations of 15, 30 and 45 s tested, the 15 s duration was found to be too short to obtain an analyzable O2-CO2 curve, but at either 30 or 45 s, the calculated values of PVCO2 were comparable to the measured PVCO2. A significant agreement between calculated and measured PVCO2 was obtained when the expired gas with PCO2 less than 22 Torr was considered as deadspace gas.

  16. Proper Estimation of the Energy Consumption in A Carbon Dioxide-MEA Stripper

    DEFF Research Database (Denmark)

    Madeddu, Claudio; Errico, Massimiliano; Baratti, Roberto

    In the field of CCS, the chemical absorption/desorption using amines represents one of the most easily implemented process for the reduction of the carbon dioxide generated by combustion plants. The high energy consumption in the solvent regeneration section represents the major concern for its...... fully industrial application. In the design of a carbon dioxide-MEA stripper, once the process targets are fixed, the estimation of the reboiler duty represents a crucial point for what concerns the quantification of the energy requirement. Furthermore, the vapor flow produced in the reboiler influences...... in simultaneous multicomponent material transfer, energy transfer and chemical reactions, is fundamental for an accurate design of the system. In this work the solvent regeneration section of a pilot-plant post-combustion CO2 capture facility was modeled using a rate-based approach, focusing on some key...

  17. Estimating dissolved organic carbon concentration in turbid coastal waters using optical remote sensing observations

    Science.gov (United States)

    Cherukuru, Nagur; Ford, Phillip W.; Matear, Richard J.; Oubelkheir, Kadija; Clementson, Lesley A.; Suber, Ken; Steven, Andrew D. L.

    2016-10-01

    Dissolved Organic Carbon (DOC) is an important component in the global carbon cycle. It also plays an important role in influencing the coastal ocean biogeochemical (BGC) cycles and light environment. Studies focussing on DOC dynamics in coastal waters are data constrained due to the high costs associated with in situ water sampling campaigns. Satellite optical remote sensing has the potential to provide continuous, cost-effective DOC estimates. In this study we used a bio-optics dataset collected in turbid coastal waters of Moreton Bay (MB), Australia, during 2011 to develop a remote sensing algorithm to estimate DOC. This dataset includes data from flood and non-flood conditions. In MB, DOC concentration varied over a wide range (20-520 μM C) and had a good correlation (R2 = 0.78) with absorption due to coloured dissolved organic matter (CDOM) and remote sensing reflectance. Using this data set we developed an empirical algorithm to derive DOC concentrations from the ratio of Rrs(412)/Rrs(488) and tested it with independent datasets. In this study, we demonstrate the ability to estimate DOC using remotely sensed optical observations in turbid coastal waters.

  18. Carbon Footprint estimation for a Sustainable Improvement of Supply Chains: State of the Art

    Directory of Open Access Journals (Sweden)

    Pilar Cordero

    2013-07-01

    Full Text Available Purpose: This paper examines the current methodologies and approaches developed to estimate carbon footprint in supply chains and the studies existing in the literature review about the application of these methodologies and other new approaches proposed by some authors.Design/methodology/approach: Literature review about methodologies developed by some authors for determining greenhouse gases emissions throughout the supply chain of a given sector or organization.Findings and Originality/value: Due to its usefulness for the design and management of a sustainable supply chain management, methodologies for calculating carbon footprint across the supply chain are recommended by many authors not only to reduce GHG emissions but also to optimize it in a cost-effective manner. Although these approaches are in first stages of development and the literature is scarce, different methodologies for estimating CF emissions which include EIO analysis models and standardized methods and guidance have been developed, some of them applicable to supply chains especially methodologies for calculating CF of a specific economic sector supply chain in a territory or country and for calculating CF of an organization applicable to the estimation of GHG emissions of a specific company supply chain.

  19. Tools to support GHG emissions reduction : a regional effort, part 1 - carbon footprint estimation and decision support.

    Science.gov (United States)

    2010-09-01

    Tools are proposed for carbon footprint estimation of transportation construction projects and decision support : for construction firms that must make equipment choice and usage decisions that affect profits, project duration : and greenhouse gas em...

  20. Estimation of carbon allocation of Macauba palm (Acrocomia aculeata) - A new Brazilian biofuel alternative

    Science.gov (United States)

    Imbuzeiro, H. A.; Moreira, S. L. S.; Motoike, S. Y.; Fernandes, R. B. A.

    2017-12-01

    The Macauba palm (Acrocomia aculeata (Jacq.) Lood. ex Mart) is a native oil palm of the tropical America growing in anthropic areas, especially in grazing lands of Brazilian Cerrado. Macauba palm displays intense fruiting which results in high fruit and oil yield (3.0 - 6.0 ton/ha/year). The main Macauba palm differentials are: it is adapted to the environment with marked water restriction (1000 mm annual precipitation) which makes it resistant to drought and it does not compete with areas of rainforest; the oil is similar in composition to the African palm oil (Elaeis guineensis Jacq.) and can be used in several industrial applications such as biofuels, food, cosmetics, pharmaceutics and oil chemistry. Additionally, Macauba fruit processing generates several by-products like edible pulp bran, high-protein edible kernel bran, dense endocarp biomass, and husk biomass, all valuable products. Today, 172 million hectares of Brazilian land are used for grazing, of which 30 million hectares of these lands are degraded due to poor land use, 6 million in the state of Minas Gerais, in Brazil. Macauba could be cultivated in these degraded lands and is a candidate to become the main raw material for production of biokerosene. A new productive chain is forming in Brazil, the first commercial plantation of Macauba was implemented last year in Minas Gerais state and it is important to estimate the environmental impacts of this plantation, in terms of carbon (C) allocation. There is a lack of experimental data on Macauba carbon allocation and this study aimed to estimate the carbon allocation (leaves, stems and roots) of Macauba palm. The results suggest that Macauba palm is important in contributing to the carbon allocation.

  1. Multidrug Efflux Systems in Microaerobic and Anaerobic Bacteria

    OpenAIRE

    Xu, Zeling; Yan, Aixin

    2015-01-01

    Active drug efflux constitutes an important mechanism of antibiotic and multidrug resistance in bacteria. Understanding the distribution, expression, and physiological functions of multidrug efflux pumps, especially under physiologically and clinically relevant conditions of the pathogens, is the key to combat drug resistance. In animal hosts, most wounded, infected and inflamed tissues display low oxygen tensions. In this article, we summarize research development on multidrug efflux pumps i...

  2. Soil carbon model alternatives for ECHAM5/JSBACH climate model: Evaluation and impacts on global carbon cycle estimates

    DEFF Research Database (Denmark)

    Thum, T.; Raisanen, P.; Sevanto, S.

    2011-01-01

    The response of soil organic carbon to climate change might lead to significant feedbacks affecting global warming. This response can be studied by coupled climate-carbon cycle models but so far the description of soil organic carbon cycle in these models has been quite simple. In this work we used...... the coupled climate-carbon cycle model ECHAM5/JSBACH (European Center/Hamburg Model 5/Jena Scheme for Biosphere-Atmosphere Coupling in Hamburg) with two different soil carbon modules, namely (1) the original soil carbon model of JSBACH called CBALANCE and (2) a new soil carbon model Yasso07, to study...... the interaction between climate variability and soil organic carbon. Equivalent ECHAM5/JSBACH simulations were conducted using both soil carbon models, with freely varying atmospheric CO2 for the last 30 years (1977-2006). In this study, anthropogenic CO2 emissions and ocean carbon cycle were excluded. The new...

  3. Designing a dynamic data driven application system for estimating real-time load of dissolved organic carbon in a river

    Science.gov (United States)

    Ying. Ouyang

    2012-01-01

    Understanding the dynamics of naturally occurring dissolved organic carbon (DOC) in a river is central to estimating surface water quality, aquatic carbon cycling, and global climate change. Currently, determination of the DOC in surface water is primarily accomplished by manually collecting samples for laboratory analysis, which requires at least 24 h. In other words...

  4. Measuring and modeling carbon stock change estimates for US forests and uncertainties from apparent inter-annual variability

    Science.gov (United States)

    James E. Smith; Linda S. Heath

    2015-01-01

    Our approach is based on a collection of models that convert or augment the USDA Forest Inventory and Analysis program survey data to estimate all forest carbon component stocks, including live and standing dead tree aboveground and belowground biomass, forest floor (litter), down deadwood, and soil organic carbon, for each inventory plot. The data, which include...

  5. Estimating urban forest carbon sequestration potential in the southern United States using current remote sensing imagery sources

    Science.gov (United States)

    Krista Merry; Pete Bettinger; Jacek Siry; J. Michael Bowker

    2015-01-01

    With an increased interest in reducing carbon dioxide in the atmosphere, tree planting and maintenance in urban areas has become a viable option for increasing carbon sequestration. Methods for assessing the potential for planting trees within an urban area should allow for quick, inexpensive, and accurate estimations of available land using current remote sensing...

  6. Evaluation and uncertainty analysis of regional-scale CLM4.5 net carbon flux estimates

    Science.gov (United States)

    Post, Hanna; Hendricks Franssen, Harrie-Jan; Han, Xujun; Baatz, Roland; Montzka, Carsten; Schmidt, Marius; Vereecken, Harry

    2018-01-01

    Modeling net ecosystem exchange (NEE) at the regional scale with land surface models (LSMs) is relevant for the estimation of regional carbon balances, but studies on it are very limited. Furthermore, it is essential to better understand and quantify the uncertainty of LSMs in order to improve them. An important key variable in this respect is the prognostic leaf area index (LAI), which is very sensitive to forcing data and strongly affects the modeled NEE. We applied the Community Land Model (CLM4.5-BGC) to the Rur catchment in western Germany and compared estimated and default ecological key parameters for modeling carbon fluxes and LAI. The parameter estimates were previously estimated with the Markov chain Monte Carlo (MCMC) approach DREAM(zs) for four of the most widespread plant functional types in the catchment. It was found that the catchment-scale annual NEE was strongly positive with default parameter values but negative (and closer to observations) with the estimated values. Thus, the estimation of CLM parameters with local NEE observations can be highly relevant when determining regional carbon balances. To obtain a more comprehensive picture of model uncertainty, CLM ensembles were set up with perturbed meteorological input and uncertain initial states in addition to uncertain parameters. C3 grass and C3 crops were particularly sensitive to the perturbed meteorological input, which resulted in a strong increase in the standard deviation of the annual NEE sum (σ ∑ NEE) for the different ensemble members from ˜ 2 to 3 g C m-2 yr-1 (with uncertain parameters) to ˜ 45 g C m-2 yr-1 (C3 grass) and ˜ 75 g C m-2 yr-1 (C3 crops) with perturbed forcings. This increase in uncertainty is related to the impact of the meteorological forcings on leaf onset and senescence, and enhanced/reduced drought stress related to perturbation of precipitation. The NEE uncertainty for the forest plant functional type (PFT) was considerably lower (σ ∑ NEE ˜ 4.0-13.5 g C

  7. New models for estimating the carbon sink capacity of Spanish softwood species

    International Nuclear Information System (INIS)

    Ruiz-Peinado, R.; Rio, M. del; Montero, G.

    2011-01-01

    Quantifying the carbon balance in forests is one of the main challenges in forest management. Forest carbon stocks are usually estimated indirectly through biomass equations applied to forest inventories, frequently considering different tree biomass components. The aim of this study is to develop systems of equations for predicting tree biomass components for the main forest softwood species in Spain: Abies alba Mill., A. pinsapo Boiss., Juniperus thurifera L., Pinus canariensis Sweet ex Spreng., P. halepensis Mill., P. nigra Arn., P. pinaster Ait., P. pinea L., P. sylvestris L., P. uncinata Mill. For each species, a system of additive biomass models was fitted using seemingly unrelated regression. Diameter at the breast height and total height were used as independent variables. Diameter appears in all component models, while tree height was included in the stem component model of all species and in some branch component equations. Total height was included in order to improve biomass estimations at different sites. These biomass models were compared to previously available equations in order to test their accuracy and it was found that they yielded better fitting statistics in all cases. Moreover, the models fulfil the additivity property. We also developed root:shoot ratios in order to determine the partitioning into aboveground and belowground biomass. A number of differences were found between species, with a minimum of 0.183 for A. alba and a maximum of 0.385 for P. uncinata. The mean value for the softwood species studied was 0.265. Since the Spanish National Forest Inventory (NFI) records species, tree diameter and height of sample trees, these biomass models and ratios can be used to accurately estimate carbon stocks from NFI data. (Author) 55 refs.

  8. New models for estimating the carbon sink capacity of Spanish softwood species

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz-Peinado, R.; Rio, M. del; Montero, G.

    2011-07-01

    Quantifying the carbon balance in forests is one of the main challenges in forest management. Forest carbon stocks are usually estimated indirectly through biomass equations applied to forest inventories, frequently considering different tree biomass components. The aim of this study is to develop systems of equations for predicting tree biomass components for the main forest softwood species in Spain: Abies alba Mill., A. pinsapo Boiss., Juniperus thurifera L., Pinus canariensis Sweet ex Spreng., P. halepensis Mill., P. nigra Arn., P. pinaster Ait., P. pinea L., P. sylvestris L., P. uncinata Mill. For each species, a system of additive biomass models was fitted using seemingly unrelated regression. Diameter at the breast height and total height were used as independent variables. Diameter appears in all component models, while tree height was included in the stem component model of all species and in some branch component equations. Total height was included in order to improve biomass estimations at different sites. These biomass models were compared to previously available equations in order to test their accuracy and it was found that they yielded better fitting statistics in all cases. Moreover, the models fulfil the additivity property. We also developed root:shoot ratios in order to determine the partitioning into aboveground and belowground biomass. A number of differences were found between species, with a minimum of 0.183 for A. alba and a maximum of 0.385 for P. uncinata. The mean value for the softwood species studied was 0.265. Since the Spanish National Forest Inventory (NFI) records species, tree diameter and height of sample trees, these biomass models and ratios can be used to accurately estimate carbon stocks from NFI data. (Author) 55 refs.

  9. Natural and Synthetic Polymers as Inhibitors of Drug Efflux Pumps

    Science.gov (United States)

    2007-01-01

    Inhibition of efflux pumps is an emerging approach in cancer therapy and drug delivery. Since it has been discovered that polymeric pharmaceutical excipients such as Tweens® or Pluronics® can inhibit efflux pumps, various other polymers have been investigated regarding their potential efflux pump inhibitory activity. Among them are polysaccharides, polyethylene glycols and derivatives, amphiphilic block copolymers, dendrimers and thiolated polymers. In the current review article, natural and synthetic polymers that are capable of inhibiting efflux pumps as well as their application in cancer therapy and drug delivery are discussed. PMID:17896100

  10. Multidrug efflux pumps in Staphylococcus aureus and their clinical implications.

    Science.gov (United States)

    Jang, Soojin

    2016-01-01

    Antibiotic resistance is rapidly spreading among bacteria such as Staphylococcus aureus, an opportunistic bacterial pathogen that causes a variety of diseases in humans. For the last two decades, bacterial multidrug efflux pumps have drawn attention due to their potential association with clinical multidrug resistance. Numerous researchers have demonstrated efflux-mediated resistance in vitro and in vivo and found novel multidrug transporters using advanced genomic information about bacteria. This article aims to provide a concise summary of multidrug efflux pumps and their important clinical implications, focusing on recent findings concerning S. aureus efflux pumps.

  11. Estimating Forest Carbon Stock in Alpine and Arctic Ecotones of the Urals

    Directory of Open Access Journals (Sweden)

    V. A. Usoltsev

    2014-10-01

    Full Text Available This paper reports on measured carbon stocks in the forests of two tree line ecotones of the Ural region where climate change might improve growing conditions. The first is an alpine ecotone that is represented by an altitudinal gradient of the spruce-dominated forests on the Western slope of the Tylaiskii Kamen Mountain (Western part of the Konzhakovskii-Tylaiskii-Serebryanskii Mountain system, 59°30′N, 59°00′E, at the alpine timber line that has risen from 864 to 960 m above sea level in the course of the last 100 years. The second is an arctic ecotone in larch-dominated forests at the lower course of the Pur river (67°N, 78°E, at the transition zone between closed floodplain forests and open or island-like communities of upland forests on tundra permafrost. According to our results, there are large differences in the carbon of the aboveground biomass of both ecotones across environmental gradients. In the alpine tree line ecotone, a 19-fold drop of the carbon stocks was detected between the lower and higher altitudinal levels. In the arctic ecotone the aboveground biomass carbon stock of forests of similar densities (1300 to 1700 trees per ha was 7 times as much in the river flood bed, and 5 times as much in mature, dense forests as the low density forests at higher elevations. Twelve regression equations describing dependencies of the aboveground tree biomass (stems, branches, foliage, total aboveground part upon stem diameter of the tree are proposed, which can be used to estimating the biological productivity (carbon of spruce and larch forests on Tylaiskii Kamen Mountain and the lower Pur river and on surrounding areas on the base of traditional forest mensuration have been proposed. In order to reduce the labor intensity of a coming determination of forest biomass the average values of density and dry matter content in the biomass fractions are given that were obtained by taking our sample trees.The results can be useful in

  12. Fractal model for estimating fracture toughness of carbon nanotube reinforced aluminum oxide

    International Nuclear Information System (INIS)

    Rishabh, Abhishek; Joshi, Milind R.; Balani, Kantesh

    2010-01-01

    The current work focuses on predicting the fracture toughness of Al 2 O 3 ceramic matrix composites using a modified Mandelbrot's fractal approach. The first step confirms that the experimental fracture toughness values fluctuate within the fracture toughness range predicted as per the modified fractal approach. Additionally, the secondary reinforcements [such as carbon nanotubes (CNTs)] have shown to enhance the fracture toughness of Al 2 O 3 . Conventional fractural toughness evaluation via fractal approach underestimates the fracture toughness by considering the shortest crack path. Hence, the modified Mandelbrot's fractal approach considers the crack propagation along the CNT semicircumferential surface (three-dimensional crack path propagation) for achieving an improved fracture toughness estimation of Al 2 O 3 -CNT composite. The estimations obtained in the current approach range within 4% error regime of the experimentally measured fracture toughness values of the Al 2 O 3 -CNT composite.

  13. Imputing forest carbon stock estimates from inventory plots to a nationally continuous coverage

    Directory of Open Access Journals (Sweden)

    Wilson Barry Tyler

    2013-01-01

    Full Text Available Abstract The U.S. has been providing national-scale estimates of forest carbon (C stocks and stock change to meet United Nations Framework Convention on Climate Change (UNFCCC reporting requirements for years. Although these currently are provided as national estimates by pool and year to meet greenhouse gas monitoring requirements, there is growing need to disaggregate these estimates to finer scales to enable strategic forest management and monitoring activities focused on various ecosystem services such as C storage enhancement. Through application of a nearest-neighbor imputation approach, spatially extant estimates of forest C density were developed for the conterminous U.S. using the U.S.’s annual forest inventory. Results suggest that an existing forest inventory plot imputation approach can be readily modified to provide raster maps of C density across a range of pools (e.g., live tree to soil organic carbon and spatial scales (e.g., sub-county to biome. Comparisons among imputed maps indicate strong regional differences across C pools. The C density of pools closely related to detrital input (e.g., dead wood is often highest in forests suffering from recent mortality events such as those in the northern Rocky Mountains (e.g., beetle infestations. In contrast, live tree carbon density is often highest on the highest quality forest sites such as those found in the Pacific Northwest. Validation results suggest strong agreement between the estimates produced from the forest inventory plots and those from the imputed maps, particularly when the C pool is closely associated with the imputation model (e.g., aboveground live biomass and live tree basal area, with weaker agreement for detrital pools (e.g., standing dead trees. Forest inventory imputed plot maps provide an efficient and flexible approach to monitoring diverse C pools at national (e.g., UNFCCC and regional scales (e.g., Reducing Emissions from Deforestation and Forest

  14. Tidal Marshes as Pulsing Systems: New Estimates of Marsh-Carbon Export and Fate

    Science.gov (United States)

    Logozzo, L. A.; Neale, P.; Tzortziou, M.; Nelson, N.; Megonigal, P.

    2016-02-01

    We investigated wetland-estuarine exchanges of dissolved organic carbon (DOC), chromophoric dissolved organic matter (CDOM), dissolved inorganic carbon (DIC), and chlorophyll a (chl a) in the Chesapeake Bay Kirkpatrick wetlands, an ecosystem that is representative of brackish marshes with organic-rich soils in North America. 1 L water samples were collected every hour over multiple semidiurnal tidal cycles (24 h deployments) and the flow was continuously measured every minute over the course of the study. DIC samples were collected and filtered on site. Fluxes were estimated using the measured flow and concentrations of biogeochemical variables (DOC, DIC, and chl a as a measure of algal biomass). aCDOM(300) was used as a proxy for CDOM amount to observe variations over two semidiurnal tidal cycles. Relative to high tide water, low tide water was consistently enriched in DOC, DIC, and CDOM, whereas it was consistently depleted in chl a. Initial estimates of fluxes over the tidal cycle showed net export of DIC and DOC from the marsh, and net import of chl a into the marsh. These results are consistent with DOC flux estimates from previous studies, but our method utilizes high temporal resolution flow measurements, improving flux estimate accuracy. Transect sampling from the marsh into the sub-estuary during ebbing tide indicated a strong negative gradient in a­CDOM­(300) and non-conservative mixing with salinity. The observed gradients in CDOM absorption spectral shape (slope and slope ratios) and the relative changes in the major fluorescence components identified in 3D fluorescence excitation-emission-matrices, indicated strong photochemical degradation in the estuary and a shift from higher to lower molecular-weight organic compounds. The weaker gradients observed for DOC and DIC compared to aCDOM(300) indicate that while microbial degradation does occur, photobleaching is the dominant degradation mechanism for CDOM in the estuary.

  15. A new method for estimating carbon dioxide emissions from transportation at fine spatial scales

    Energy Technology Data Exchange (ETDEWEB)

    Shu Yuqin [School of Geographical Science, South China Normal University, Guangzhou 510631 (China); Lam, Nina S N; Reams, Margaret, E-mail: gis_syq@126.com, E-mail: nlam@lsu.edu, E-mail: mreams@lsu.edu [Department of Environmental Sciences, Louisiana State University, Baton Rouge, 70803 (United States)

    2010-10-15

    Detailed estimates of carbon dioxide (CO{sub 2}) emissions at fine spatial scales are useful to both modelers and decision makers who are faced with the problem of global warming and climate change. Globally, transport related emissions of carbon dioxide are growing. This letter presents a new method based on the volume-preserving principle in the areal interpolation literature to disaggregate transportation-related CO{sub 2} emission estimates from the county-level scale to a 1 km{sup 2} grid scale. The proposed volume-preserving interpolation (VPI) method, together with the distance-decay principle, were used to derive emission weights for each grid based on its proximity to highways, roads, railroads, waterways, and airports. The total CO{sub 2} emission value summed from the grids within a county is made to be equal to the original county-level estimate, thus enforcing the volume-preserving property. The method was applied to downscale the transportation-related CO{sub 2} emission values by county (i.e. parish) for the state of Louisiana into 1 km{sup 2} grids. The results reveal a more realistic spatial pattern of CO{sub 2} emission from transportation, which can be used to identify the emission 'hot spots'. Of the four highest transportation-related CO{sub 2} emission hotspots in Louisiana, high-emission grids literally covered the entire East Baton Rouge Parish and Orleans Parish, whereas CO{sub 2} emission in Jefferson Parish (New Orleans suburb) and Caddo Parish (city of Shreveport) were more unevenly distributed. We argue that the new method is sound in principle, flexible in practice, and the resultant estimates are more accurate than previous gridding approaches.

  16. Estimation of the Carbon Footprint and Global Warming Potential in Rice Production Systems

    International Nuclear Information System (INIS)

    Dastan, S.; Soltani, F.; Noormohamadi, G.; Madani, H.; Yadi, R.

    2016-01-01

    Optimal management approaches can be adopted in order to increase crop productivity and lower the carbon footprint of grain products. The objective of this study was to estimate the carbon (C) footprint and global warming potential of rice production systems. In this experiment, rice production systems (including SRI, improved and conventional) were studied. All activities, field operations and data in production methods and at different input rates were monitored and recorded during 2012. Results showed that average global warming potential across production systems was equal to 2803.25 kg CO 2 -eq ha-1. The highest and least global warming potential were observed in the SRI and conventional systems, respectively. global warming potential per unit energy input was the least and most in SRI and conventional systems, respectively. Also, the SRI and conventional systems had the maximum and minimum global warming potential per unit energy output, respectively. SRI and conventional system had the greatest and least global warming potential per unit energy output, respectively. Therefore, the optimal management approach found in SRI resulted in a reduction in GHGs, global warming potential and the carbon footprint.

  17. Estimated flows of gases and carbon within CEEF ecosystem composed of human, crops and goats

    Science.gov (United States)

    Tako, Y.; Komatsubara, O.; Honda, G.; Arai, R.; Nitta, K.

    The Closed Ecology Experiment Facilities (CEEF) can be used as a test bed for Controlled Ecological Life Support Systems (CELSS), because technologies developed for the CEEF system facilitate self-sufficient material circulation necessary for long term missions such as Lunar and Mars exploration. In the experiment conducted under closed condition in FY2003, rice and soybeans were cultivated sequentially in two chambers and a chamber, each having a cultivation area of 30 m2 and floor area of 43 m2, inside the Plantation Module with artificial lighting of the CEEF. In the chamber having a cultivation area of 60 m2 and floor area of 65 m2, inside the Plantation Module with natural and artificial lighting, peanuts and safflowers were also cultivated. Stable transplant (or seeding) and harvest of each crop were maintained during a month. Flows of CO2, O2 and carbon to and from the crops were analyzed during the stable cultivation period. Simulated works and stay in the CEEF lasting five days were conducted two times under ventilating condition in FY2003. Gas exchange of human was estimated using heart rate data collected during the experiments and correlation between gas exchange rate and heart rate. Gas exchange rate and carbon balance of female goats were determined using an open-flow measurement system with a gastight chamber. From these results, flows of gases and carbon in the CEEF were discussed.

  18. The effect to the water stress to soil CO2 efflux in the Siberian boreal forest

    Science.gov (United States)

    Makhnykina, A. V.; Prokishkin, A. S.; Verkhovets, S. V.; Koshurnikova, N. N.

    2017-12-01

    The boreal forests in Siberia covered more than 70% area of this region. Due to the climate change this ecosystems represent a very sensitive and significant source of carbon. In forests, total ecosystem respiration tends to be dominated by soil respiration, which accounts for approximately 69% of this large flux (Janssens et al., 2001). Dynamic global vegetation models predict that soil respiration will increase more than total net primary productivity in response to warmer temperatures and increase in precipitation, the terrestrial carbon sink is expected to decline significantly (Bonan et al., 2003). The aim of the present study was to identify the response of the soil CO2 efflux to the different amount of water input for two highly differentiated years by the precipitation conditions in the middle taiga forests in Central Siberia. The study was conducted in the pine forests in Central Siberia (60°N, 90°E), Russia. We used the automated soil CO2 flux system LI-8100 for measuring the soil efflux. Soil temperature was measured with Soil Temperature Probe Type E in three depths 5, 10, 15 cm. Volumetric soil moisture was measured with Theta Probe Model ML2. We constructed the field experiment based on the addition of different amount of water (0%, 25%, 50% and 100% sites) after each rain event during the growing season. We found that the amount of precipitation have a huge impact to the value of soil CO2 efflux. For the more precipitated year (2015) the fluxes were almost twice higher compared to less precipitated year (2016). The max fluxes during the season in 2015 observed at the site without any water input there and the min one - for the 100% precipitation site (natural rain conditions). In 2016 we identified the opposite response: the max soil efflux demonstrated the site with 100% precipitation conditions (Fig. 1). We also detected the high dependence between the soil temperature and soil CO2 efflux for the site with 0% additional water input in more

  19. Factors controlling carbon isotopic composition of land snail shells estimated from lab culturing experiment

    Science.gov (United States)

    Zhang, Naizhong; Yamada, Keita; Yoshida, Naohiro

    2014-05-01

    Carbon isotopic composition (δ13C) of land snail shell carbonate is widely applied in reconstructing the C3/C4 vegetation distribution of paleo-environment, which is considered to reflect variations of some environmental parameters [1][2][3]. Land snail shell carbon has three potential sources: diet, atmospheric CO2 and ingested carbonate (limestone) [4]. However, their relative contributions to shell carbonate have not been understood well yet [4][5][6][7][8]. More researches are necessary before we could apply this tool in paleo-environment reconstruction, especially inter-lab culturing experiment. A kind of land snail species, Acusta despecta sieboldiana, was collected at Yokohama, Japan and cultured under suitable environment to lay eggs. The second generations were growing up from eggs to adults around 6-12 months at the temperature of 20°, 25° and 30°, respectively. All of the snails at 25° and 30° and most of those at 20° were fed by cabbage (C3 plant) during their life span while others were fed by corn (C4 plant). To investigate the effect of ingested carbonate, some of them were fed by Ca3(PO4)2 powder while others were fed by CaCO3 powder. δ13C of shells were analyzed by an Isotope Ratio Mass Spectrometry (Thermo Finnigan MAT 253); δ13C of food and snail tissue were measured by a Cavity Ring-Down Spectroscopy (Picarro G1121-i). At the same time, δ13C of eggshell and new born snails were analyzed by a Continuous Flow Isotope Ratio Mass Spectrometry (GasBench II). We confirmed that diet, atmospheric CO2 and ingested limestone could be important sources controlling shell δ13C values. And the temperature could affect shell carbonate δ13C values, too. A simple but credible frame was raised to discuss the mechanism of how each possible source and environmental parameter could affect shell carbonate δ13C values based on previous works [4][6][8] and this study. According to this frame and some reasonable assumptions, we have estimated the

  20. Tripartite assembly of RND multidrug efflux pumps.

    Science.gov (United States)

    Daury, Laetitia; Orange, François; Taveau, Jean-Christophe; Verchère, Alice; Monlezun, Laura; Gounou, Céline; Marreddy, Ravi K R; Picard, Martin; Broutin, Isabelle; Pos, Klaas M; Lambert, Olivier

    2016-02-12

    Tripartite multidrug efflux systems of Gram-negative bacteria are composed of an inner membrane transporter, an outer membrane channel and a periplasmic adaptor protein. They are assumed to form ducts inside the periplasm facilitating drug exit across the outer membrane. Here we present the reconstitution of native Pseudomonas aeruginosa MexAB-OprM and Escherichia coli AcrAB-TolC tripartite Resistance Nodulation and cell Division (RND) efflux systems in a lipid nanodisc system. Single-particle analysis by electron microscopy reveals the inner and outer membrane protein components linked together via the periplasmic adaptor protein. This intrinsic ability of the native components to self-assemble also leads to the formation of a stable interspecies AcrA-MexB-TolC complex suggesting a common mechanism of tripartite assembly. Projection structures of all three complexes emphasize the role of the periplasmic adaptor protein as part of the exit duct with no physical interaction between the inner and outer membrane components.

  1. Numerical estimation of the effective electrical conductivity in carbon paper diffusion media

    International Nuclear Information System (INIS)

    Zamel, Nada; Li, Xianguo; Shen, Jun

    2012-01-01

    Highlights: ► Anisotropic effective electrical conductivity of the GDL is estimated numerically. ► The electrical conductivity is a key component in understanding the structure of the GDL. ► Expressions for evaluating the electrical conductivity were proposed. ► The tortuosity factor was evaluated as 1.7 and 3.4 in the in- and through-plane directions, respectively. - Abstract: The transport of electrons through the gas diffusion layer (GDL) of polymer electrolyte membrane (PEM) fuel cells has a significant impact on the optimal design and operation of PEM fuel cells and is directly affected by the anisotropic nature of the carbon paper material. In this study, a three-dimensional reconstruction of the GDL is used to numerically estimate the directional dependent effective electrical conductivity of the layer for various porosity values. The distribution of the fibers in the through-plane direction results in high electrical resistivity; hence, decreasing the overall effective electrical conductivity in this direction. This finding is in agreement with measured experimental data. Further, using the numerical results of this study, two mathematical expressions were proposed for the calculation of the effective electrical conductivity of the carbon paper GDL. Finally, the tortuosity factor was evaluated as 1.7 and 3.4 in the in- and through-plane directions, respectively.

  2. High-Resolution Forest Canopy Height Estimation in an African Blue Carbon Ecosystem

    Science.gov (United States)

    Lagomasino, David; Fatoyinbo, Temilola; Lee, Seung-Kuk; Simard, Marc

    2015-01-01

    Mangrove forests are one of the most productive and carbon dense ecosystems that are only found at tidally inundated coastal areas. Forest canopy height is an important measure for modeling carbon and biomass dynamics, as well as land cover change. By taking advantage of the flat terrain and dense canopy cover, the present study derived digital surface models (DSMs) using stereophotogrammetric techniques on high-resolution spaceborne imagery (HRSI) for southern Mozambique. A mean-weighted ground surface elevation factor was subtracted from the HRSI DSM to accurately estimate the canopy height in mangrove forests in southern Mozambique. The mean and H100 tree height measured in both the field and with the digital canopy model provided the most accurate results with a vertical error of 1.18-1.84 m, respectively. Distinct patterns were identified in the HRSI canopy height map that could not be discerned from coarse shuttle radar topography mission canopy maps even though the mode and distribution of canopy heights were similar over the same area. Through further investigation, HRSI DSMs have the potential of providing a new type of three-dimensional dataset that could serve as calibration/validation data for other DSMs generated from spaceborne datasets with much larger global coverage. HSRI DSMs could be used in lieu of Lidar acquisitions for canopy height and forest biomass estimation, and be combined with passive optical data to improve land cover classifications.

  3. A First Regional-Scale Estimate of Climate-Driven Terrestrial Carbon Export in Boreal Catchments

    Directory of Open Access Journals (Sweden)

    Nazzareno Diodato

    2018-03-01

    Full Text Available Highly dynamic hydro-geomorphic processes are known to drive exports of carbon (C from river basins, but are not yet fully understood. Within this study, we simulated total organic carbon (TOC exports at the outlet of Lake Simojärvi in the Gulf of Bothnia (Finland with a parsimonious hydrological model. With thorough consideration of the dependence of erosion and sediment transport processes on seasonal precipitation rates, a satisfactory agreement was obtained between modelling and experimental observations (1962–2005. This provided confidence in the capability of the parsimonious model to represent temporal and spatial export dynamics. In the period 1860–2014, TOC export at the outlet of Lake Simojärvi was estimated to be highest on average (~5.5 Mg km−2·year−1 over 1974–2014 while the lowest TOC export (~2.5 Mg km−2·year−1 was estimated in 1860–1918 (with high levels of interannual-to-multidecadal variation. Regional simulations indicate that TOC increased in recent decades (on average, 4–5 Mg km−2·year−1 in 1974–2014 against ~3 Mg km−2·year−1 in 1940–1973 in northern Scandinavia and Finland. Warming-induced variability of TOC (which depends on precipitation patterns may have altered the rates of C exchanges in aquatic ecosystems over recent years. TOC exports may continue to increase in boreal catchments with increasing temperatures as represented by future projections.

  4. Engineering bacterial efflux pumps for solar-powered bioremediation of surface waters.

    Science.gov (United States)

    Kapoor, Vikram; Wendell, David

    2013-05-08

    Antibiotics are difficult to selectively remove from surface waters by present treatment methods. Bacterial efflux pumps have evolved the ability to discriminately expel antibiotics and other noxious agents via proton and ATP driven pathways. Here, we describe light-dependent removal of antibiotics by engineering the bacterial efflux pump AcrB into a proteovesicle system. We have created a chimeric protein with the requisite proton motive force by coupling AcrB to the light-driven proton pump Delta-rhodopsin (dR) via a glycophorin A transmembrane domain. This creates a solar powered protein material capable of selectively capturing antibiotics from bulk solutions. Using environmental water and direct sunlight, our AcrB-dR vesicles removed almost twice as much antibiotic as the treatment standard, activated carbon. Altogether, the AcrB-dR system provides an effective means of extracting antibiotics from surface waters as well as potential antibiotic recovery through vesicle solubilization.

  5. Estimating the carbon budget and maximizing future carbon uptake for a temperate forest region in the U.S.

    Science.gov (United States)

    Scott D. Peckham; Stith T. Gower; Joseph Buongiorno

    2012-01-01

    Forests of the Midwest U.S. provide numerous ecosystem services. Two of these, carbon sequestration and wood production, are often portrayed as conflicting. Currently, carbon management and biofuel policies are being developed to reduce atmospheric CO2 and national dependence on foreign oil, and increase carbon storage in ecosystems. However, the biological and...

  6. Estimates of forest biomass carbon storage inLiaoning Province of Northeast China: a review and assessment.

    Science.gov (United States)

    Yu, Dapao; Wang, Xiaoyu; Yin, You; Zhan, Jinyu; Lewis, Bernard J; Tian, Jie; Bao, Ye; Zhou, Wangming; Zhou, Li; Dai, Limin

    2014-01-01

    Accurate estimates of forest carbon storage and changes in storage capacity are critical for scientific assessment of the effects of forest management on the role of forests as carbon sinks. Up to now, several studies reported forest biomass carbon (FBC) in Liaoning Province based on data from China's Continuous Forest Inventory, however, their accuracy were still not known. This study compared estimates of FBC in Liaoning Province derived from different methods. We found substantial variation in estimates of FBC storage for young and middle-age forests. For provincial forests with high proportions in these age classes, the continuous biomass expansion factor method (CBM) by forest type with age class is more accurate and therefore more appropriate for estimating forest biomass. Based on the above approach designed for this study, forests in Liaoning Province were found to be a carbon sink, with carbon stocks increasing from 63.0 TgC in 1980 to 120.9 TgC in 2010, reflecting an annual increase of 1.9 TgC. The average carbon density of forest biomass in the province has increased from 26.2 Mg ha(-1) in 1980 to 31.0 Mg ha(-1) in 2010. While the largest FBC occurred in middle-age forests, the average carbon density decreased in this age class during these three decades. The increase in forest carbon density resulted primarily from the increased area and carbon storage of mature forests. The relatively long age interval in each age class for slow-growing forest types increased the uncertainty of FBC estimates by CBM-forest type with age class, and further studies should devote more attention to the time span of age classes in establishing biomass expansion factors for use in CBM calculations.

  7. Estimation of carbon emission from peatland fires using Landsat-8 OLI imagery in Siak District, Riau Province

    Science.gov (United States)

    Aisyah Fadhillah Hafni, Dinda; Syaufina, Lailan; Puspaningsih, Nining; Prasasti, Indah

    2018-05-01

    The study was conducted in three land cover conditions (secondary peat forest, shrub land, and palm plantation) that were burned in the Siak District, Riau Province, Indonesia year 2015. Measurement and calculation carbon emission from soil and vegetation of peatland should be done accurately to be implemented on climate change mitigation or greenhouse gases mitigation. The objective of the study was to estimate the carbon emission caused peatland fires in the Siak District, Riau Province, Indonesia year 2015. Estimated carbon emissions were performed using visual method and digital method. The visual method was a method that uses on-screen digitization assisted by hotspot data, the presence of smoke, and fire suppression data. The digital method was a method that uses the Normalized Burn Ratio (NBR) index. The estimated carbon emissions were calculated using the equation that was developed from IPCC 2006 in Verified Carbon Standard 2015. The results showed that the estimation of carbon emissions from fires from above the peat soil surface were higher than the carbon emissions from the peat soil. Carbon emissions above the peat soil surface of 1376.51 ton C/ha were obtained by visual method while 3984.33 ton C/ha were obtained by digital method. Peatland carbon emissions of 6.6 x 10-4 ton C/ha were obtained by visual method, whereas 2.84 x 10-3 ton C/ha was obtained by digital method. Visual method and digital method using remote sensing must be combined and developed in order to carbon emission values will be more accurate.

  8. CarbonTracker-Lagrange: A Framework for Greenhouse Gas Flux Estimation at Regional to Continental Scales

    Science.gov (United States)

    Andrews, A. E.

    2016-12-01

    CarbonTracker-Lagrange (CT-L) is a flexible modeling framework developed to take advantage of newly available atmospheric data for CO2 and other long-lived gases such as CH4 and N2O. The North American atmospheric CO2 measurement network has grown from three sites in 2004 to >100 sites in 2015. The US network includes tall tower, mountaintop, surface, and aircraft sites in the NOAA Global Greenhouse Gas Reference Network along with sites maintained by university, government and private sector researchers. The Canadian network is operated by Environment and Climate Change Canada. This unprecedented dataset can provide spatially and temporally resolved CO2 emissions and uptake flux estimates and quantitative information about drivers of variability, such as drought and temperature. CT-L is a platform for systematic comparison of data assimilation techniques and evaluation of assumed prior, model and observation errors. A novel feature of CT-L is the optimization of boundary values along with surface fluxes, leveraging vertically resolved data available from NOAA's aircraft sampling program. CT-L uses observation footprints (influence functions) from the Weather Research and Forecasting/Stochastic Time-Inverted Lagrangian Transport (WRF-STILT) modeling system to relate atmospheric measurements to upwind fluxes and boundary values. Footprints are pre-computed and the optimization algorithms are efficient, so many variants of the calculation can be performed. Fluxes are adjusted using Bayesian or Geostatistical methods to provide optimal agreement with observations. Satellite measurements of CO2 and CH4 from GOSAT are available starting in July 2009 and from OCO-2 since September 2014. With support from the NASA Carbon Monitoring System, we are developing flux estimation strategies that use remote sensing and in situ data together, including geostatistical inversions using satellite retrievals of solar-induced chlorophyll fluorescence. CT-L enables quantitative

  9. Comparisons of allometric and climate-derived estimates of tree coarse root carbon stocks in forests of the United States

    Science.gov (United States)

    Matthew B. Russell; Grant M. Domke; Christopher W. Woodall; Anthony W. D' Amato

    2015-01-01

    Background: Refined estimation of carbon (C) stocks within forest ecosystems is a critical component of efforts to reduce greenhouse gas emissions and mitigate the effects of projected climate change through forest C management. Specifically, belowground C stocks are currently estimated in the United States' national greenhouse gas inventory (US NGHGI) using...

  10. Methods and equations for estimating aboveground volume, biomass, and carbon for trees in the U.S. forest inventory, 2010

    Science.gov (United States)

    Christopher W. Woodall; Linda S. Heath; Grant M. Domke; Michael C. Nichols

    2011-01-01

    The U.S. Forest Service, Forest Inventory and Analysis (FIA) program uses numerous models and associated coefficients to estimate aboveground volume, biomass, and carbon for live and standing dead trees for most tree species in forests of the United States. The tree attribute models are coupled with FIA's national inventory of sampled trees to produce estimates of...

  11. Carbon Dioxide Evasion from Boreal Lakes: Drivers, Variability and Revised Global Estimate

    Science.gov (United States)

    Hastie, A. T.; Lauerwald, R.; Weyhenmeyer, G. A.; Sobek, S.; Verpoorter, C.; Regnier, P. A. G.

    2016-12-01

    Carbon dioxide evasion (FCO2) from lakes and reservoirs is established as an important component of the global carbon (C) cycle, a fact reflected by the inclusion of these waterbodies in the most recent IPCC assessment report. In this study we developed a statistical model driven by environmental geodata, to predict CO2 partial pressure (pCO2) in boreal lakes, and to create the first high resolution map (0.5°) of boreal (50°- 70°) lake pCO2. The resulting map of pCO2 was combined with lake area (lakes >0.01km2) from the recently developed GLOWABO database (Verpoorter et al., 2014) and estimates of gas transfer velocity k, to produce the first high resolution map of boreal lake FCO2. Before training our model, the geodata as well as approximately 27,000 samples of `open water' (excluding periods of ice cover) pCO2 from the boreal region, were gridded at 0.5° resolution and log transformed where necessary. A multilinear regression was used to derive a prediction equation for log10 pCO2 as a function of log10 lake area, net primary productivity (NPP), precipitation, wind speed and soil pH (r2= 0.66), and then applied in ArcGIS to build the map of pCO2. After validation, the map of boreal lake pCO2 was used to derive a map of boreal lake FCO2. For the boreal region we estimate an average, lake area weighted, pCO2 of 930 μatm and FCO2 of 170 (121-243) Tg C yr-1. Our estimate of FCO2 will soon be updated with the incorporation of the smallest lakes (<0.01km2). Despite the current exclusion of the smallest lakes, our estimate is higher than the highest previous estimate of approximately 110 Tg C yr-1 (Aufdenkampe et al, 2011). Moreover, our empirical approach driven by environmental geodata can be used as the basis for estimating future FCO2 from boreal lakes, and their sensitivity to climate change.

  12. Empirical observations offer improved estimates of forest floor carbon content across in the United States

    Science.gov (United States)

    Perry, C. H.; Domke, G. M.; Walters, B. F.; Smith, J. E.; Woodall, C. W.

    2014-12-01

    The Forest Inventory and Analysis (FIA) program of the United States Forest Service reports official estimates of national forest floor carbon (FFC) stocks and stock change to national and international parties, the US Environmental Protection Agency (USEPA) and the United Nations Framework Convention on Climate Change (UNFCCC), respectively. These estimates of national FFC stocks are derived from plot-level predictions of FFC density. We suspect the models used to predict plot-level FFC density are less than ideal for several reasons: (a) they are based upon local studies that may not reflect FFC dynamics at the national scale, (b) they are relatively insensitive to climate change, and (c) they reduce the natural variability of the data leading to misplaced confidence in the estimates. However, FIA has measured forest floor attributes since 2001 on a systematic 1/16th subset of a nation-wide array of inventory plots (7 800 of 125 000 plots). Here we address the efficacy of replacing plot-level model predictions with empirical observations of FFC density while assessing the impact of imputing FFC density values to the full plot network on national stock estimates. First, using an equivalence testing framework, we found model predictions of FFC density to differ significantly from the observations in all regions and forest types; the mean difference across all plots was 21 percent (1.81 Mg·ha-1). Furthermore, the model predictions were biased towards the lower end of extant FFC density observations, underestimating it while greatly truncating the range relative to the observations. Second, the optimal imputation approach (k-Nearest Neighbor, k-NN) resulted in values that were equivalent to observations of FFC density across a range of simulated missingness and maintained the high variability seen in the observations. We used the k-NN approach to impute FFC density values to the 94 percent of FIA inventory plots without soil measurements. Third, using the imputed

  13. Role of bacterial efflux pumps in biofilm formation.

    Science.gov (United States)

    Alav, Ilyas; Sutton, J Mark; Rahman, Khondaker Miraz

    2018-02-28

    Efflux pumps are widely implicated in antibiotic resistance because they can extrude the majority of clinically relevant antibiotics from within cells to the extracellular environment. However, there is increasing evidence from many studies to suggest that the pumps also play a role in biofilm formation. These studies have involved investigating the effects of efflux pump gene mutagenesis and efflux pump inhibitors on biofilm formation, and measuring the levels of efflux pump gene expression in biofilms. In particular, several key pathogenic species associated with increasing multidrug resistance, such as Acinetobacter baumannii, Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus, have been investigated, whilst other studies have focused on Salmonella enterica serovar Typhimurium as a model organism and problematic pathogen. Studies have shown that efflux pumps, including AcrAB-TolC of E. coli, MexAB-OprM of P. aeruginosa, AdeFGH of A. baumannii and AcrD of S. enterica, play important roles in biofilm formation. The substrates for such pumps, and whether changes in their efflux activity affect biofilm formation directly or indirectly, remain to be determined. By understanding the roles that efflux pumps play in biofilm formation, novel therapeutic strategies can be developed to inhibit their function, to help disrupt biofilms and improve the treatment of infections. This review will discuss and evaluate the evidence for the roles of efflux pumps in biofilm formation and the potential approaches to overcome the increasing problem of biofilm-based infections.

  14. Detection of efflux pump activity among clinical isolates of ...

    African Journals Online (AJOL)

    Purpose: To detect efflux pump activity (EPA) and screening a suspected efflux pump inhibitor (EPI) [1- (3-(trifluoromethyl)benzyl]-piperazine (TFMBP)], which could help in reducing multi-drug resistance (MDR). Methods: Eighteen isolates, viz, 14 S. aureus, 2 S. lentus, 1 S. xylosus and 1 Micrococcus species from various ...

  15. [Estimation of Topsoil Carbon Sequestration Potential of Cropland Through Different Methods: A Case Study in Zhuanglang County, Gansu Province].

    Science.gov (United States)

    Shi, Chen-di; Xu, Ming-xiang; Qiu, Yu-jie

    2016-03-15

    By analyzing the sampled data and the SOC data of the second national soil survey by the mid 80s and the national cultivated land quality evaluation in 2006 in Zhuanglang County, the article studied the cropland topsoil organic carbon sequestration potential estimation using several different methods. The results showed that: (1) There was no significant difference among different estimation methods about cropland carbon sequestration potential in the same region. Taking cropland carbon sequestration potential in Zhuanglang County for example, the theoretical values estimated by maximum value method and classification grading method were 1. 13 Mt and 1.09 Mt, respectively. (2) The real values estimated by classification grading method, saturation method, weighting method were 0.37 Mt, 0.32 Mt, 0.28 Mt, respectively, which were about 1/3 of the theoretical value. (3) The SOC density increments to reach the real level of carbon sequestration potential estimated by classification grading method, saturation method and weighting method were 6.76 t · hm⁻², 5.21 t · hm⁻², 4.56 t · hm⁻² respectively. According to the topsoil carbon sequestration rate of cropland in Zhuanglang county in the recent 30 a, it would need about 24-34 a to achieve the real level. (4) At the county scale, the weighted method was superior to the saturation value method, and the saturation value method was better than the classification grading method in the actual carbon sequestration potential estimation. The classification grading method was better than the maximum value method in the ideal carbon sequestration potential estimation.

  16. Fluorometric determination of ethidium bromide efflux kinetics in Escherichia coli

    Directory of Open Access Journals (Sweden)

    Monteiro Gabriel A

    2009-10-01

    Full Text Available Abstract Background Efflux pump activity has been associated with multidrug resistance phenotypes in bacteria, compromising the effectiveness of antimicrobial therapy. The development of methods for the early detection and quantification of drug transport across the bacterial cell wall is a tool essential to understand and overcome this type of drug resistance mechanism. This approach was developed to study the transport of the efflux pump substrate ethidium bromide (EtBr across the cell envelope of Escherichia coli K-12 and derivatives, differing in the expression of their efflux systems. Results EtBr transport across the cell envelope of E. coli K-12 and derivatives was analysed by a semi-automated fluorometric method. Accumulation and efflux of EtBr was studied under limiting energy supply (absence of glucose and low temperature and in the presence and absence of the efflux pump inhibitor, chlorpromazine. The bulk fluorescence variations were also observed by single-cell flow cytometry analysis, revealing that once inside the cells, leakage of EtBr does not occur and that efflux is mediated by active transport. The importance of AcrAB-TolC, the main efflux system of E. coli, in the extrusion of EtBr was evidenced by comparing strains with different levels of AcrAB expression. An experimental model was developed to describe the transport kinetics in the three strains. The model integrates passive entry (influx and active efflux of EtBr, and discriminates different degrees of efflux between the studied strains that vary in the activity of their efflux systems, as evident from the calculated efflux rates: = 0.0173 ± 0.0057 min-1; = 0.0106 ± 0.0033 min-1; and = 0.0230 ± 0.0075 min-1. Conclusion The combined use of a semi-automated fluorometric method and an experimental model allowed quantifying EtBr transport in E. coli strains that differ in their overall efflux activity. This methodology can be used for the early detection of differences in

  17. On the use of phloem sap δ13C to estimate canopy carbon discrimination

    Science.gov (United States)

    Rascher, Katherine; Máguas, Cristina; Werner, Christiane

    2010-05-01

    along the canopy to trunk continuum. We further hypothesize that pronounced depletion along the basipetal transport pathway in A. longifolia (more than 6 per mil from leaf water soluble organic matter to trunk phloem sap) may be due to high stem photosynthesis rates in this green-barked legume. Regardless of these fractionation effects, phloem sap d13C correlated well with environmental parameters driving photosynthesis (photosynthetic photon flux density, soil moisture, vapor pressure deficit) for both species indicating that phloem sap d13C is a good integrative tracer of changes in canopy-level carbon discrimination once species-specific differences in post-photosynthetic fractionation are accounted for. Furthermore, we illustrate that combining sap flow estimated canopy stomatal conductance (gs) with measurements of phloem sap d13C (adjusted for post-photosynthetic fractionation) has significant potential as a relatively non-intensive method for estimating canopy-level carbon assimilation rates in field studies.

  18. Efflux of inorganic substances from young barley roots, (2)

    International Nuclear Information System (INIS)

    Fujimoto, Hiroshi; Kojima, Shigeru

    1977-01-01

    The root system of young barley was almost halved, and the two portions were planted in culture grounds with different composition after severing the capillary connection between both root groups. With one portion in the acid medium solution of various compositions and the other in the 22 Na-absorbing medium solution, the sodium absorbed from one root group moved to and flowed out from the other root group, and this state was observed. Also, the efflux of potassium from the root was observed. (1) The Na efflux was small in the culture ground with dilute hydrochloric acid, and larger in that with AlCl 3 or phosphate. (2) The K efflux was large under short-day condition. (3) Under short-day condition, in the culture ground with soluble Al, the K efflux was promoted by nitrogen-source addition, but the Na efflux was suppressed. (Mori, K.)

  19. A method countries can use to estimate changes in carbon stored in harvested wood products and the uncertainty of such estimates

    Science.gov (United States)

    Kenneth E. Skog; Kim Pingoud; James E. Smith

    2004-01-01

    A method is suggested for estimating additions to carbon stored in harvested wood products (HWP) and for evaluating uncertainty. The method uses data on HWP production and trade from several decades and tracks annual additions to pools of HWP in use, removals from use, additions to solid waste disposal sites (SWDS), and decay from SWDS. The method is consistent with...

  20. Soil efflux and total emission rates of magmatic CO2 at the horseshoe lake tree kill, mammoth mountain, California, 1995-1999

    Science.gov (United States)

    Gerlach, T.M.; Doukas, M.P.; McGee, K.A.; Kessler, R.

    2001-01-01

    We report the results of eight soil CO2 efflux surveys by the closed circulation chamber method at the Horseshoe Lake tree kill (HLTK) - the largest tree kill on Mammoth Mountain. The surveys were undertaken from 1995 to 1999 to constrain total HLTK CO2 emissions and to evaluate occasional efflux surveys as a surveillance tool for the tree kills. HLTK effluxes range from 1 to > 10,000 g m -2 day -1 (grams CO2 per square meter per day); they are not normally distributed. Station efflux rates can vary by 7-35% during the course of the 8- to 16-h surveys. Disturbance of the upper 2 cm of ground surface causes effluxes to almost double. Semivariograms of efflux spatial covariance fit exponential or spherical models; they lack nugget effects. Efflux contour maps and total CO2 emission rates based on exponential, spherical, and linear kriging models of survey data are nearly identical; similar results are also obtained with triangulation models, suggesting that the kriging models are not seriously distorted by the lack of normal efflux distributions. In addition, model estimates of total CO2 emission rates are relatively insensitive to the measurement precision of the efflux rates and to the efflux value used to separate magmatic from forest soil sources of CO2. Surveys since 1997 indicate that, contrary to earlier speculations, a termination of elevated CO2 emissions at the HLTK is unlikely anytime soon. The HLTK CO2 efflux anomaly fluctuated greatly in size and intensity throughout the 1995-1999 surveys but maintained a N-S elongation, presumably reflecting fault control of CO2 transport from depth. Total CO2 emission rates also fluctuated greatly, ranging from 46 to 136 t day-1 (metric tons CO2 per day) and averaging 93 t day-1. The large inter-survey variations are caused primarily by external (meteorological) processes operating on time scales of hours to days. The externally caused variations can mask significant changes occurring at depth; a striking example is

  1. Improving global fire carbon emissions estimates by combining moderate resolution burned area and active fire observations

    Science.gov (United States)

    Randerson, J. T.; Chen, Y.; Giglio, L.; Rogers, B. M.; van der Werf, G.

    2011-12-01

    In several important biomes, including croplands and tropical forests, many small fires exist that have sizes that are well below the detection limit for the current generation of burned area products derived from moderate resolution spectroradiometers. These fires likely have important effects on greenhouse gas and aerosol emissions and regional air quality. Here we developed an approach for combining 1km thermal anomalies (active fires; MOD14A2) and 500m burned area observations (MCD64A1) to estimate the prevalence of these fires and their likely contribution to burned area and carbon emissions. We first estimated active fires within and outside of 500m burn scars in 0.5 degree grid cells during 2001-2010 for which MCD64A1 burned area observations were available. For these two sets of active fires we then examined mean fire radiative power (FRP) and changes in enhanced vegetation index (EVI) derived from 16-day intervals immediately before and after each active fire observation. To estimate the burned area associated with sub-500m fires, we first applied burned area to active fire ratios derived solely from within burned area perimeters to active fires outside of burn perimeters. In a second step, we further modified our sub-500m burned area estimates using EVI changes from active fires outside and within of burned areas (after subtracting EVI changes derived from control regions). We found that in northern and southern Africa savanna regions and in Central and South America dry forest regions, the number of active fires outside of MCD64A1 burned areas increased considerably towards the end of the fire season. EVI changes for active fires outside of burn perimeters were, on average, considerably smaller than EVI changes associated with active fires inside burn scars, providing evidence for burn scars that were substantially smaller than the 25 ha area of a single 500m pixel. FRP estimates also were lower for active fires outside of burn perimeters. In our

  2. Using LUCAS topsoil database to estimate soil organic carbon content in local spectral libraries

    Science.gov (United States)

    Castaldi, Fabio; van Wesemael, Bas; Chabrillat, Sabine; Chartin, Caroline

    2017-04-01

    The quantification of the soil organic carbon (SOC) content over large areas is mandatory to obtain accurate soil characterization and classification, which can improve site specific management at local or regional scale exploiting the strong relationship between SOC and crop growth. The estimation of the SOC is not only important for agricultural purposes: in recent years, the increasing attention towards global warming highlighted the crucial role of the soil in the global carbon cycle. In this context, soil spectroscopy is a well consolidated and widespread method to estimate soil variables exploiting the interaction between chromophores and electromagnetic radiation. The importance of spectroscopy in soil science is reflected by the increasing number of large soil spectral libraries collected in the world. These large libraries contain soil samples derived from a consistent number of pedological regions and thus from different parent material and soil types; this heterogeneity entails, in turn, a large variability in terms of mineralogical and organic composition. In the light of the huge variability of the spectral responses to SOC content and composition, a rigorous classification process is necessary to subset large spectral libraries and to avoid the calibration of global models failing to predict local variation in SOC content. In this regard, this study proposes a method to subset the European LUCAS topsoil database into soil classes using a clustering analysis based on a large number of soil properties. The LUCAS database was chosen to apply a standardized multivariate calibration approach valid for large areas without the need for extensive field and laboratory work for calibration of local models. Seven soil classes were detected by the clustering analyses and the samples belonging to each class were used to calibrate specific partial least square regression (PLSR) models to estimate SOC content of three local libraries collected in Belgium (Loam belt

  3. COPATH - a spreadsheet model for the estimation of carbon flows associated with the use of forest resources

    International Nuclear Information System (INIS)

    Makundi, W.; Sathaye, J.; Ketoff, A.

    1995-01-01

    The forest sector plays a key role in the global climate change process. A significant amount of net greenhouse gas emissions emanate from land use changes, and the sector offers a unique opportunity to sequester carbon in vegetation, detritus, soils and forest products. However, the estimates of carbon flows associated with the use of forest resources have been quite imprecise. This paper describes a methodological framework-COPATH-which is a spreadsheet model for estimating carbon emissions and sequestration from deforestation and harvesting of forests. The model has two parts, the first estimates carbon stocks, emissions and uptake in the base year, while the second part forecasts future emissions and the uptake under various scenarios. The forecast module is structured after the main modes of forest conversion, i.e. agriculture, pasture, forest harvesting and other land uses. The model can be used by countries which may not possess an abundance of pertinent data, and allows for the use of forest inventory data to estimate carbon stocks. The choice of the most likely scenario provides the country with a carbon flux profile necessary to formulate GHG mitigation strategies. (Author)

  4. Reducing uncertainty for estimating forest carbon stocks and dynamics using integrated remote sensing, forest inventory and process-based modeling

    Science.gov (United States)

    Poulter, B.; Ciais, P.; Joetzjer, E.; Maignan, F.; Luyssaert, S.; Barichivich, J.

    2015-12-01

    Accurately estimating forest biomass and forest carbon dynamics requires new integrated remote sensing, forest inventory, and carbon cycle modeling approaches. Presently, there is an increasing and urgent need to reduce forest biomass uncertainty in order to meet the requirements of carbon mitigation treaties, such as Reducing Emissions from Deforestation and forest Degradation (REDD+). Here we describe a new parameterization and assimilation methodology used to estimate tropical forest biomass using the ORCHIDEE-CAN dynamic global vegetation model. ORCHIDEE-CAN simulates carbon uptake and allocation to individual trees using a mechanistic representation of photosynthesis, respiration and other first-order processes. The model is first parameterized using forest inventory data to constrain background mortality rates, i.e., self-thinning, and productivity. Satellite remote sensing data for forest structure, i.e., canopy height, is used to constrain simulated forest stand conditions using a look-up table approach to match canopy height distributions. The resulting forest biomass estimates are provided for spatial grids that match REDD+ project boundaries and aim to provide carbon estimates for the criteria described in the IPCC Good Practice Guidelines Tier 3 category. With the increasing availability of forest structure variables derived from high-resolution LIDAR, RADAR, and optical imagery, new methodologies and applications with process-based carbon cycle models are becoming more readily available to inform land management.

  5. Carbon-enhanced Metal-poor Stars in SDSS/SEGUE. I. Carbon Abundance Estimation and Frequency of CEMP Stars

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Young Sun [NMSU, Las Cruces; Beers, Timothy C. [Michigan State U., JINA; Masseron, Thomas [Brussels U.; Plez, Bertrand [U. Montpellier 2, LUPM; Rockosi, Constance M. [Lick Observ.; Sobeck, Jennifer [Chicago U.; Yanny, Brian [Fermilab; Lucatello, Sara [Padua Observ.; Sivarani, Thirupathi [Bangalore, Indian Inst. Astrophys.; Placco, Vinicius M. [Sao Paulo U., IAG; Carollo, Daniela [Macquarie U.

    2013-10-17

    We describe a method for the determination of stellar [C/Fe] abundance ratios using low-resolution (R = 2000) stellar spectra from the SDSS and SEGUE. By means of a star-by-star comparison with a set of SDSS/SEGUE spectra with available estimates of [C/Fe] based on published high-resolution analyses, we demonstrate that we can measure [C/Fe] from SDSS/SEGUE spectra with S/N > 15 to a precision better than 0.35 dex. Using the measured carbon-to-iron abundance ratios obtained by this technique, we derive the frequency of carbon-enhanced stars ([C/Fe] > +0.7) as a function of [Fe/H], for both the SDSS/SEGUE stars and other samples from the literature. We find that the differential frequency slowly rises from almost zero to about 14% at [Fe/H] ~ -2.4, followed by a sudden increase, by about a factor of three, to 39% from [Fe/H] ~ -2.4 to [Fe/H] ~ -3.7. We also examine how the cumulative frequency of CEMP stars varies across different luminosity classes. The giant sample exhibits a cumulative CEMP frequency of 32% for [Fe/H] < -2.5, 31% for [Fe/H] < -3.0, and 33% for [Fe/H] < -3.5. For the main-sequence turnoff stars, we obtain a lower cumulative CEMP frequency, around 10% for [Fe/H] < -2.5. The dwarf population displays a large change in the cumulative frequency for CEMP stars below [Fe/H] = -2.5, jumping from 15% for [Fe/H] < -2.5 to about 75% for [Fe/H] < -3.0. When we impose a restriction with respect to distance from the Galactic mid-plane (|Z| < 5 kpc), the frequency of the CEMP giants does not increase at low metallicity ([Fe/H] < -2.5), but rather, decreases, due to the dilution of C-rich material in stars that have undergone mixing with CNO-processed material from their interiors. The frequency of CEMP stars near the main-sequence turnoff, which are not expected to have experienced mixing, increases for [Fe/H] < -3.0. [abridged

  6. Carbon dioxide efflux in a rhodic hapludox as affected by tillage systems in southern Brazil Emissão de dióxido de carbono em latossolo vermelho alterada por sistemas de preparo no sul do Brasil

    Directory of Open Access Journals (Sweden)

    Luis Fernando Chavez

    2009-04-01

    Full Text Available Agricultural soils can act as a source or sink of atmospheric C, according to the soil management. This long-term experiment (22 years was evaluated during 30 days in autumn, to quantify the effect of tillage systems (conventional tillage-CT and no-till-NT on the soil CO2-C flux in a Rhodic Hapludox in Rio Grande do Sul State, Southern Brazil. A closed-dynamic system (Flux Chamber 6400-09, Licor and a static system (alkali absorption were used to measure soil CO2-C flux immediately after soybean harvest. Soil temperature and soil moisture were measured simultaneously with CO2-C flux, by Licor-6400 soil temperature probe and manual TDR, respectively. During the entire month, a CO2-C emission of less than 30 % of the C input through soybean crop residues was estimated. In the mean of a 30 day period, the CO2-C flux in NT soil was similar to CT, independent of the chamber type used for measurements. Differences in tillage systems with dynamic chamber were verified only in short term (daily evaluation, where NT had higher CO2-C flux than CT at the beginning of the evaluation period and lower flux at the end. The dynamic chamber was more efficient than the static chamber in capturing variations in CO2-C flux as a function of abiotic factors. In this chamber, the soil temperature and the water-filled pore space (WFPS, in the NT soil, explained 83 and 62 % of CO2-C flux, respectively. The Q10 factor, which evaluates CO2-C flux dependence on soil temperature, was estimated as 3.93, suggesting a high sensitivity of the biological activity to changes in soil temperature during fall season. The CO2-C flux measured in a closed dynamic chamber was correlated with the static alkali adsorption chamber only in the NT system, although the values were underestimated in comparison to the other, particularly in the case of high flux values. At low soil temperature and WFPS conditions, soil tillage caused a limited increase in soil CO2-C flux.Os solos agr

  7. Methane oxidation by termite mounds estimated by the carbon isotopic composition of methane

    Science.gov (United States)

    Sugimoto, Atsuko; Inoue, Tetsushi; Kirtibutr, Nit; Abe, Takuya

    1998-12-01

    Emission rates and carbon isotope ratios of CH4, emitted by workers of termites, and of CH4, emitted from their mounds, were observed in a dry evergreen forest in Thailand to estimate the proportion of CH4 oxidized during emission through the mound. The δ13C of CH4 emitted from a termite mound (-70.9 to -82.4‰) was higher than that of CH4 emitted by workers in the mound (-85.4 to -97. l‰). Using a fractionation factor (a = 0.987) for oxidation of CH4 which was obtained in the incubation experiment, an emission factor defined as (CH4 emitted from a termite mound/CH4 produced by termites) was calculated. The emission factor obtained in each termite mound was nearly zero for Macrotermes (fungus-growing termites), of which the nest has a thick soil wall and subterrannean termites, and 0.17 to 0.47 for Termitinae (small-mound-making termites). Global CH4 emission by termites was estimated on the basis of the CH4 emission rates by workers and termite biomass with the emission factors. The calculated result was 1.5 to 7.4 Tg/y (0.3 to 1.3% of total source), which is considerably smaller than the estimate by the IPCC [1994].

  8. Uncertainties in neural network model based on carbon dioxide concentration for occupancy estimation

    Energy Technology Data Exchange (ETDEWEB)

    Alam, Azimil Gani; Rahman, Haolia; Kim, Jung-Kyung; Han, Hwataik [Kookmin University, Seoul (Korea, Republic of)

    2017-05-15

    Demand control ventilation is employed to save energy by adjusting airflow rate according to the ventilation load of a building. This paper investigates a method for occupancy estimation by using a dynamic neural network model based on carbon dioxide concentration in an occupied zone. The method can be applied to most commercial and residential buildings where human effluents to be ventilated. An indoor simulation program CONTAMW is used to generate indoor CO{sub 2} data corresponding to various occupancy schedules and airflow patterns to train neural network models. Coefficients of variation are obtained depending on the complexities of the physical parameters as well as the system parameters of neural networks, such as the numbers of hidden neurons and tapped delay lines. We intend to identify the uncertainties caused by the model parameters themselves, by excluding uncertainties in input data inherent in measurement. Our results show estimation accuracy is highly influenced by the frequency of occupancy variation but not significantly influenced by fluctuation in the airflow rate. Furthermore, we discuss the applicability and validity of the present method based on passive environmental conditions for estimating occupancy in a room from the viewpoint of demand control ventilation applications.

  9. Inversely estimating the vertical profile of the soil CO2 production rate in a deciduous broadleaf forest using a particle filtering method.

    Science.gov (United States)

    Sakurai, Gen; Yonemura, Seiichiro; Kishimoto-Mo, Ayaka W; Murayama, Shohei; Ohtsuka, Toshiyuki; Yokozawa, Masayuki

    2015-01-01

    Carbon dioxide (CO2) efflux from the soil surface, which is a major source of CO2 from terrestrial ecosystems, represents the total CO2 production at all soil depths. Although many studies have estimated the vertical profile of the CO2 production rate, one of the difficulties in estimating the vertical profile is measuring diffusion coefficients of CO2 at all soil depths in a nondestructive manner. In this study, we estimated the temporal variation in the vertical profile of the CO2 production rate using a data assimilation method, the particle filtering method, in which the diffusion coefficients of CO2 were simultaneously estimated. The CO2 concentrations at several soil depths and CO2 efflux from the soil surface (only during the snow-free period) were measured at two points in a broadleaf forest in Japan, and the data were assimilated into a simple model including a diffusion equation. We found that there were large variations in the pattern of the vertical profile of the CO2 production rate between experiment sites: the peak CO2 production rate was at soil depths around 10 cm during the snow-free period at one site, but the peak was at the soil surface at the other site. Using this method to estimate the CO2 production rate during snow-cover periods allowed us to estimate CO2 efflux during that period as well. We estimated that the CO2 efflux during the snow-cover period (about half the year) accounted for around 13% of the annual CO2 efflux at this site. Although the method proposed in this study does not ensure the validity of the estimated diffusion coefficients and CO2 production rates, the method enables us to more closely approach the "actual" values by decreasing the variance of the posterior distribution of the values.

  10. A New Global LAI Product and Its Use for Terrestrial Carbon Cycle Estimation

    Science.gov (United States)

    Chen, J. M.; Liu, R.; Ju, W.; Liu, Y.

    2014-12-01

    For improving the estimation of the spatio-temporal dynamics of the terrestrial carbon cycle, a new time series of the leaf area index (LAI) is generated for the global land surface at 8 km resolution from 1981 to 2012 by combining AVHRR and MODIS satellite data. This product differs from existing LAI products in the following two aspects: (1) the non-random spatial distribution of leaves with the canopy is considered, and (2) the seasonal variation of the vegetation background is included. The non-randomness of the leaf spatial distribution in the canopy is considered using the second vegetation structural parameter named clumping index (CI), which quantifies the deviation of the leaf spatial distribution from the random case. Using the MODIS Bidirectional Reflectance Distribution Function product, a global map of CI is produced at 500 m resolution. In our LAI algorithm, CI is used to convert the effective LAI obtained from mono-angle remote sensing into the true LAI, otherwise LAI would be considerably underestimated. The vegetation background is soil in crop, grass and shrub but includes soil, grass, moss, and litter in forests. Through processing a large volume of MISR data from 2000 to 2010, monthly red and near-infrared reflectances of the vegetation background is mapped globally at 1 km resolution. This new LAI product has been validated extensively using ground-based LAI measurements distributed globally. In carbon cycle modeling, the use of CI in addition to LAI allows for accurate separation of sunlit and shaded leaves as an important step in terrestrial photosynthesis and respiration modeling. Carbon flux measurements over 100 sites over the globe are used to validate an ecosystem model named Boreal Ecosystem Productivity Simulator (BEPS). The validated model is run globally at 8 km resolution for the period from 1981 to 2012 using the LAI product and other spatial datasets. The modeled results suggest that changes in vegetation structure as quantified

  11. Estimating ecosystem carbon change in the Conterminous United States based on 40 years of land-use change and disturbance

    Science.gov (United States)

    Sleeter, B. M.; Rayfield, B.; Liu, J.; Sherba, J.; Daniel, C.; Frid, L.; Wilson, T. S.; Zhu, Z.

    2016-12-01

    Since 1970, the combined changes in land use, land management, climate, and natural disturbances have dramatically altered land cover in the United States, resulting in the potential for significant changes in terrestrial carbon storage and flux between ecosystems and the atmosphere. Processes including urbanization, agricultural expansion and contraction, and forest management have had impacts - both positive and negative - on the amount of natural vegetation, the age structure of forests, and the amount of impervious cover. Anthropogenic change coupled with climate-driven changes in natural disturbance regimes, particularly the frequency and severity of wildfire, together determine the spatio-temporal patterns of land change and contribute to changing ecosystem carbon dynamics. Quantifying this effect and its associated uncertainties is fundamental to developing a rigorous and transparent carbon monitoring and assessment programs. However, large-scale systematic inventories of historical land change and their associated uncertainties are sparse. To address this need, we present a newly developed modeling framework, the Land Use and Carbon Scenario Simulator (LUCAS). The LUCAS model integrates readily available high quality, empirical land-change data into a stochastic space-time simulation model representing land change feedbacks on carbon cycling in terrestrial ecosystems. We applied the LUCAS model to estimate regional scale changes in carbon storage, atmospheric flux, and net biome production in 84 ecological regions of the conterminous United States for the period 1970-2015. The model was parameterized using a newly available set of high resolution (30 m) land-change data, compiled from Landsat remote sensing imagery, including estimates of uncertainty. Carbon flux parameters for each ecological region were derived from the IBIS dynamic global vegetation model with full carbon cycle accounting. This paper presents our initial findings describing regional and

  12. Stem girdling affects the quantity of CO2 transported in xylem as well as CO2 efflux from soil.

    Science.gov (United States)

    Bloemen, Jasper; Agneessens, Laura; Van Meulebroek, Lieven; Aubrey, Doug P; McGuire, Mary Anne; Teskey, Robert O; Steppe, Kathy

    2014-02-01

    There is recent clear evidence that an important fraction of root-respired CO2 is transported upward in the transpiration stream in tree stems rather than fluxing to the soil. In this study, we aimed to quantify the contribution of root-respired CO2 to both soil CO2 efflux and xylem CO2 transport by manipulating the autotrophic component of belowground respiration. We compared soil CO2 efflux and the flux of root-respired CO2 transported in the transpiration stream in girdled and nongirdled 9-yr-old oak trees (Quercus robur) to assess the impact of a change in the autotrophic component of belowground respiration on both CO2 fluxes. Stem girdling decreased xylem CO2 concentration, indicating that belowground respiration contributes to the aboveground transport of internal CO2 . Girdling also decreased soil CO2 efflux. These results confirmed that root respiration contributes to xylem CO2 transport and that failure to account for this flux results in inaccurate estimates of belowground respiration when efflux-based methods are used. This research adds to the growing body of evidence that efflux-based measurements of belowground respiration underestimate autotrophic contributions. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

  13. National-scale estimation of gross forest aboveground carbon loss: a case study of the Democratic Republic of the Congo

    International Nuclear Information System (INIS)

    Tyukavina, A; Potapov, P V; Turubanova, S A; Hansen, M C; Stehman, S V; Baccini, A; Goetz, S J; Laporte, N T; Houghton, R A

    2013-01-01

    Recent advances in remote sensing enable the mapping and monitoring of carbon stocks without relying on extensive in situ measurements. The Democratic Republic of the Congo (DRC) is among the countries where national forest inventories (NFI) are either non-existent or out of date. Here we demonstrate a method for estimating national-scale gross forest aboveground carbon (AGC) loss and associated uncertainties using remotely sensed-derived forest cover loss and biomass carbon density data. Lidar data were used as a surrogate for NFI plot measurements to estimate carbon stocks and AGC loss based on forest type and activity data derived using time-series multispectral imagery. Specifically, DRC forest type and loss from the FACET (Forêts d’Afrique Centrale Evaluées par Télédétection) product, created using Landsat data, were related to carbon data derived from the Geoscience Laser Altimeter System (GLAS). Validation data for FACET forest area loss were created at a 30-m spatial resolution and compared to the 60-m spatial resolution FACET map. We produced two gross AGC loss estimates for the DRC for the last decade (2000–2010): a map-scale estimate (53.3 ± 9.8 Tg C yr −1 ) accounting for whole-pixel classification errors in the 60-m resolution FACET forest cover change product, and a sub-grid estimate (72.1 ± 12.7 Tg C yr −1 ) that took into account 60-m cells that experienced partial forest loss. Our sub-grid forest cover and AGC loss estimates, which included smaller-scale forest disturbances, exceed published assessments. Results raise the issue of scale in forest cover change mapping and validation, and subsequent impacts on remotely sensed carbon stock change estimation, particularly for smallholder dominated systems such as the DRC. (letter)

  14. Metamodeling-based approach for risk assessment and cost estimation: Application to geological carbon sequestration planning

    Science.gov (United States)

    Sun, Alexander Y.; Jeong, Hoonyoung; González-Nicolás, Ana; Templeton, Thomas C.

    2018-04-01

    Carbon capture and storage (CCS) is being evaluated globally as a geoengineering measure for significantly reducing greenhouse emission. However, long-term liability associated with potential leakage from these geologic repositories is perceived as a main barrier of entry to site operators. Risk quantification and impact assessment help CCS operators to screen candidate sites for suitability of CO2 storage. Leakage risks are highly site dependent, and a quantitative understanding and categorization of these risks can only be made possible through broad participation and deliberation of stakeholders, with the use of site-specific, process-based models as the decision basis. Online decision making, however, requires that scenarios be run in real time. In this work, a Python based, Leakage Assessment and Cost Estimation (PyLACE) web application was developed for quantifying financial risks associated with potential leakage from geologic carbon sequestration sites. PyLACE aims to assist a collaborative, analytic-deliberative decision making processes by automating metamodel creation, knowledge sharing, and online collaboration. In PyLACE, metamodeling, which is a process of developing faster-to-run surrogates of process-level models, is enabled using a special stochastic response surface method and the Gaussian process regression. Both methods allow consideration of model parameter uncertainties and the use of that information to generate confidence intervals on model outputs. Training of the metamodels is delegated to a high performance computing cluster and is orchestrated by a set of asynchronous job scheduling tools for job submission and result retrieval. As a case study, workflow and main features of PyLACE are demonstrated using a multilayer, carbon storage model.

  15. Estimation of Carbon Dioxide Emissions Generated by Building and Traffic in Taichung City

    Directory of Open Access Journals (Sweden)

    Chou-Tsang Chang

    2018-01-01

    Full Text Available The emissions of carbon dioxide generated by urban traffic is generally reflected by urban size. In order to discuss the traffic volume generated in developed buildings and road crossings in a single urban block, with the metropolitan area in Taichung, Taiwan as an example, this study calculates the mutual relationship between the carbon dioxide generated by the traffic volume and building development scale, in order to research energy consumption and relevance. In this research, the entire-day traffic volume of an important road crossing is subject to statistical analysis to obtain the prediction formula of total passenger car units in the main road crossing within 24 h. Then, the total CO2 emissions generated by the traffic volume in the entire year is calculated according to the investigation data of peak traffic hours within 16 blocks and the influential factors of the development scale of 95 buildings are counted. Finally, this research found that there is a passenger car unit of 4.72 generated in each square meter of land in the urban block every day, 0.99 in each square meter of floor area in the building and the average annual total CO2 emissions of each passenger car unit is 41.4 kgCO2/yr. In addition, the basic information of an integrated road system and traffic volume is used to present a readable urban traffic hot map, which can calculate a distribution map of passenger car units within one day in Taichung. This research unit can be used to forecast the development scale of various buildings in future urban blocks, in order to provide an effective approach to estimate the carbon dioxide generated by the traffic volume.

  16. Estimation of Surface Temperature and Heat Flux by Inverse Heat Transfer Methods Using Internal Temperatures Measured While Radiantly Heating a Carbon/Carbon Specimen up to 1920 F

    Science.gov (United States)

    Pizzo, Michelle; Daryabeigi, Kamran; Glass, David

    2015-01-01

    The ability to solve the heat conduction equation is needed when designing materials to be used on vehicles exposed to extremely high temperatures; e.g. vehicles used for atmospheric entry or hypersonic flight. When using test and flight data, computational methods such as finite difference schemes may be used to solve for both the direct heat conduction problem, i.e., solving between internal temperature measurements, and the inverse heat conduction problem, i.e., using the direct solution to march forward in space to the surface of the material to estimate both surface temperature and heat flux. The completed research first discusses the methods used in developing a computational code to solve both the direct and inverse heat transfer problems using one dimensional, centered, implicit finite volume schemes and one dimensional, centered, explicit space marching techniques. The developed code assumed the boundary conditions to be specified time varying temperatures and also considered temperature dependent thermal properties. The completed research then discusses the results of analyzing temperature data measured while radiantly heating a carbon/carbon specimen up to 1920 F. The temperature was measured using thermocouple (TC) plugs (small carbon/carbon material specimens) with four embedded TC plugs inserted into the larger carbon/carbon specimen. The purpose of analyzing the test data was to estimate the surface heat flux and temperature values from the internal temperature measurements using direct and inverse heat transfer methods, thus aiding in the thermal and structural design and analysis of high temperature vehicles.

  17. Three approaches for estimating recovery factors in carbon dioxide enhanced oil recovery

    Science.gov (United States)

    Verma, Mahendra K.

    2017-07-17

    PrefaceThe Energy Independence and Security Act of 2007 authorized the U.S. Geological Survey (USGS) to conduct a national assessment of geologic storage resources for carbon dioxide (CO2) and requested the USGS to estimate the “potential volumes of oil and gas recoverable by injection and sequestration of industrial carbon dioxide in potential sequestration formations” (42 U.S.C. 17271(b)(4)). Geologic CO2 sequestration associated with enhanced oil recovery (EOR) using CO2 in existing hydrocarbon reservoirs has the potential to increase the U.S. hydrocarbon recoverable resource. The objective of this report is to provide detailed information on three approaches that can be used to calculate the incremental recovery factors for CO2-EOR. Therefore, the contents of this report could form an integral part of an assessment methodology that can be used to assess the sedimentary basins of the United States for the hydrocarbon recovery potential using CO2-EOR methods in conventional oil reservoirs.

  18. Soil CO2 efflux of a larch forest in northern Japan

    Directory of Open Access Journals (Sweden)

    Y. Fujinuma

    2010-11-01

    Full Text Available We had continuously measured soil CO2 efflux (Rs in a larch forest in northern Japan at hourly intervals for the snow-free period in 2003 with an automated chamber system and partitioned Rs into heterotrophic respiration (Rh and autotrophic respiration (Rr by using the trench method. In addition, we applied the soil CO2 concentration gradients method to continuously measure soil CO2 profiles under snowpack in the snowy period and to partition Rs into topsoil (Oa and A horizons CO2 efflux (Ft with a depth of 0.13 m and sub-soil (C horizon CO2 efflux (Fc. We found that soil CO2 effluxes were strongly affected by the seasonal variation of soil temperature but weakly correlated with soil moisture, probably because the volumetric soil moisture (30–40% at 95% confidence interval was within a plateau region for root and microbial activities. The soil CO2 effluxes changed seasonally in parallel with soil temperature in topsoil with the peak in late summer. On the other hand, the contribution of Rr to Rs was the largest at about 50% in early summer, when canopy photosynthesis and plant growth were more active. The temperature sensitivity (Q10 of Rr peaked in June. Under snowpack, Rs was stable until mid-March and then gradually increased with snow melting. Rs summed up to 79 gC m−2 during the snowy season for 4 months. The annual Rs was determined at 934 gC m−2 y−1 in 2003, which accounted for 63% of ecosystem respiration. The annual contributions of Rh and Rs to Rs were 57% and 43%, respectively. Based on the gradient approach, Rs was partitioned vertically into litter (Oi and Oe horizons with a depth of 0.01–0.02 m, topsoil and sub-soil respirations with proportions of 6, 72 and 22%, respectively, on an annual basis. The vertical distribution of CO2 efflux was consistent with those of soil carbon and root biomass.

  19. Estimating temporal changes in soil carbon stocks at ecoregional scale in Madagascar using remote-sensing

    Science.gov (United States)

    Grinand, C.; Maire, G. Le; Vieilledent, G.; Razakamanarivo, H.; Razafimbelo, T.; Bernoux, M.

    2017-02-01

    Soil organic carbon (SOC) plays an important role in climate change regulation notably through release of CO2 following land use change such a deforestation, but data on stock change levels are lacking. This study aims to empirically assess SOC stocks change between 1991 and 2011 at the landscape scale using easy-to-access spatially-explicit environmental factors. The study area was located in southeast Madagascar, in a region that exhibits very high rate of deforestation and which is characterized by both humid and dry climates. We estimated SOC stock on 0.1 ha plots for 95 different locations in a 43,000 ha reference area covering both dry and humid conditions and representing different land cover including natural forest, cropland, pasture and fallows. We used the Random Forest algorithm to find out the environmental factors explaining the spatial distribution of SOC. We then predicted SOC stocks for two soil layers at 30 cm and 100 cm over a wider area of 395,000 ha. By changing the soil and vegetation indices derived from remote sensing images we were able to produce SOC maps for 1991 and 2011. Those estimates and their related uncertainties where combined in a post-processing step to map estimates of significant SOC variations and we finally compared the SOC change map with published deforestation maps. Results show that the geologic variables, precipitation, temperature, and soil-vegetation status were strong predictors of SOC distribution at regional scale. We estimated an average net loss of 10.7% and 5.2% for the 30 cm and the 100 cm layers respectively for deforested areas in the humid area. Our results also suggest that these losses occur within the first five years following deforestation. No significant variations were observed for the dry region. This study provides new solutions and knowledge for a better integration of soil threats and opportunities in land management policies.

  20. Emissions estimates of carbon tetrachloride for 1992-2014 in China.

    Science.gov (United States)

    Bie, Pengju; Fang, Xuekun; Li, Zhifang; Wang, Ziyuan; Hu, Jianxin

    2017-05-01

    Discrepancies in emission estimates of carbon tetrachloride (CCl 4 , CTC), between bottom-up and top-down methods, have been shown since the 1990s at both the global and regional scale. This study estimates the emissions of China from 1992 to 2014 based on emission functions and aggregated activity information given reasonable uncertainties. The results show that emissions increase from 7.3 Gg/yr (5.6-9.1 Gg/yr at 95% confidential interval) to 14.0 (9.1-19.5) Gg/yr with a growth rate of 6.7 (1.9-11.4) %/yr during 1992-2002 and then decrease to a minimum of 4.3 (1.9-8.0) Gg/yr in 2011. More than 54% of the emissions during 1992-2009 are from the process agents sector. The estimates are comparable with those of other studies and those in this study based on observations during 2011-2014 using the interspecies correlation method. China's contribution to global emissions increases from 7.5% to 19.5% during 1992-2009, but the contribution is reduced to 9.9% and 8.0% in 2010 and 2011, respectively, indicating the effectiveness of compliance with the Montreal Protocol and its subsequent Amendments and Adjustments, whereby CTC emissions are phased-out. The results of this study are beneficial for narrowing the gap between bottom-up estimates and top-down emission calculations of CTC in China. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Renouvellement du carbone profond des sols cultivés : une estimation par compilation de données isotopiques

    Directory of Open Access Journals (Sweden)

    Balesdent, J.

    2017-01-01

    Full Text Available Turnover of deep organic carbon in cultivated soils: an estimate from a review of isotope data. Description of the subject. This study is an estimate of medium-term renewal (decades of deep carbon in cultivated soils. Objectives. Sequestration of organic carbon in soils is a way to mitigate the global rise in CO2 and warming. Deep horizons (> 30 cm contain about half of the soil organic carbon but, in agriculture, deep organic carbon and nitrogen are often neglected when the balance of these elements is calculated. Our goal in this study was to propose a quantification of deep C turnover. Method. We collected data from 41 profiles, where C turnover was studied using the natural 13C labeling technique. The studied cropping systems were basically tropical and temperate C4 plant monocultures. Results. Deep carbon (30 – 100 cm turnover was on average four times slower than in topsoil (0 – 30 cm, but renewal was significant. The average depth-distribution of the carbon flux to organic matter build-up was 81% in the layer at the 0 – 30 cm level and 19% in the layer at 30 – 100 cm, with a standard error of ± 4%. Over the longer term (20 years, subsoil at 30 – 100 cm contained on average 23% of the recent soil carbon accumulated in the first meter. Conclusions. Deep organic matter should not be overlooked when considering the balance of C and N and we therefore propose a simple method for an initial first assessment. In the future, further estimates of the temporal evolution of the deep carbon stock and its factors of variation should be based on long-term agronomic experiments or modeling parameterized on heavily instrumented sites, and should be accompanied by detailed pedological descriptions.

  2. Diffusion-type model of the global carbon cycle for the estimation of dose to the world population from releases of carbon-14 to the atmosphere

    International Nuclear Information System (INIS)

    Killough, G.G.

    1977-05-01

    A nonlinear dynamic model of the exchange of carbon among the atmosphere, terrestrial biosphere, and ocean is described and applied to estimating the radiation dose to the world's population from the release of 14 C to the atmosphere from the nuclear power industry. A computer implementation of the model, written in the IBM Continuous System Modeling Program III (CSMP III) simulation language, is presented. The model treats the ocean as a diffusive medium with respect to vertical transport of carbon, and the nonlinear variation of CO 2 partial pressure with the total inorganic carbon concentration in surface waters is taken into account in calculating the transfer rate from ocean to atmosphere. Transfers between the atmosphere and terrestrial biosphere are represented by nonlinear equations which consider CO 2 fertilization and impose a constraint on the ultimate total carbon mass in the biosphere

  3. Total Belowground Carbon Allocation in a Fast-growing Eucalyptus Plantation Estimated Using a Carbon Balance Approach

    Science.gov (United States)

    Christian P. Giardina; Michael G. Ryan

    2002-01-01

    Trees allocate a large portion of gross primary production belowground for the production and maintenance of roots and mycorrhizae. The difficulty of directly measuring total belowground carbon allocation (TBCA) has limited our understanding of belowground carbon (C) cycling and the factors that control this important flux. We measured TBCA over 4 years using a...

  4. Estimating net ecosystem exchange of carbon using the normalized difference vegetation index and an ecosystem model

    International Nuclear Information System (INIS)

    Veroustraete, F.; Patyn, J.; Myneni, R.B.

    1996-01-01

    The evaluation and prediction of changes in carbon dynamics at the ecosystem level is a key issue in studies of global change. An operational concept for the determination of carbon fluxes for the Belgian territory is the goal of the presented study. The approach is based on the integration of remotely sensed data into ecosystem models in order to evaluate photosynthetic assimilation and net ecosystem exchange (NEE). Remote sensing can be developed as an operational tool to determine the fraction of absorbed photosynthetically active radiation (feAR). A review of the methodological approach of mapping fPAR dynamics at the regional scale by means of NOAA11-A VHRR / 2 data for the year 1990 is given. The processing sequence from raw radiance values to fPAR is presented. An interesting aspect of incorporating remote sensing derived fPAR in ecosystem models is the potential for modeling actual as opposed to potential vegetation. Further work should prove whether the concepts presented and the assumptions made in this study are valid. (NEE). Complex ecosystem models with a highly predictive value for a specific ecosystem are generally not suitable for global or regional applications, since they require a substantial set of ancillary data becoming increasingly larger with increasing complexity of the model. The ideal model for our purpose is one that is simple enough to be used in global scale modeling, and which can be adapted for different ecosystems or vegetation types. The fraction of absorbed photosynthetically active radiation (fPAR) during the growing season determines in part net photosynthesis and phytomass production (Ruimy, 1995). Remotely measured red and near-infrared spectral reflectances can be used to estimate fPAR. Therefore, a possible approach is to estimate net photosynthesis, phytomass, and NEE from a combination of satellite data and an ecosystem model that includes carbon dynamics. It has to be stated that some parts of the work presented in this

  5. Non-destructive estimates of soil carbonic anhydrase activity and associated soil water oxygen isotope composition

    Science.gov (United States)

    Jones, Sam P.; Ogée, Jérôme; Sauze, Joana; Wohl, Steven; Saavedra, Noelia; Fernández-Prado, Noelia; Maire, Juliette; Launois, Thomas; Bosc, Alexandre; Wingate, Lisa

    2017-12-01

    The contribution of photosynthesis and soil respiration to net land-atmosphere carbon dioxide (CO2) exchange can be estimated based on the differential influence of leaves and soils on budgets of the oxygen isotope composition (δ18O) of atmospheric CO2. To do so, the activity of carbonic anhydrases (CAs), a group of enzymes that catalyse the hydration of CO2 in soils and plants, needs to be understood. Measurements of soil CA activity typically involve the inversion of models describing the δ18O of CO2 fluxes to solve for the apparent, potentially catalysed, rate of CO2 hydration. This requires information about the δ18O of CO2 in isotopic equilibrium with soil water, typically obtained from destructive, depth-resolved sampling and extraction of soil water. In doing so, an assumption is made about the soil water pool that CO2 interacts with, which may bias estimates of CA activity if incorrect. Furthermore, this can represent a significant challenge in data collection given the potential for spatial and temporal variability in the δ18O of soil water and limited a priori information with respect to the appropriate sampling resolution and depth. We investigated whether we could circumvent this requirement by inferring the rate of CO2 hydration and the δ18O of soil water from the relationship between the δ18O of CO2 fluxes and the δ18O of CO2 at the soil surface measured at different ambient CO2 conditions. This approach was tested through laboratory incubations of air-dried soils that were re-wetted with three waters of different δ18O. Gas exchange measurements were made on these soils to estimate the rate of hydration and the δ18O of soil water, followed by soil water extraction to allow for comparison. Estimated rates of CO2 hydration were 6.8-14.6 times greater than the theoretical uncatalysed rate of hydration, indicating that CA were active in these soils. Importantly, these estimates were not significantly different among water treatments, suggesting

  6. Estimating the carbon budget and maximizing future carbon uptake for a temperate forest region in the U.S.

    Science.gov (United States)

    2012-01-01

    Background Forests of the Midwest U.S. provide numerous ecosystem services. Two of these, carbon sequestration and wood production, are often portrayed as conflicting. Currently, carbon management and biofuel policies are being developed to reduce atmospheric CO2 and national dependence on foreign oil, and increase carbon storage in ecosystems. However, the biological and industrial forest carbon cycles are rarely studied in a whole-system structure. The forest system carbon balance is the difference between the biological (net ecosystem production) and industrial (net emissions from forest industry) forest carbon cycles, but to date this critical whole system analysis is lacking. This study presents a model of the forest system, uses it to compute the carbon balance, and outlines a methodology to maximize future carbon uptake in a managed forest region. Results We used a coupled forest ecosystem process and forest products life cycle inventory model for a regional temperate forest in the Midwestern U.S., and found the net system carbon balance for this 615,000 ha forest was positive (2.29 t C ha-1 yr-1). The industrial carbon budget was typically less than 10% of the biological system annually, and averaged averaged 0.082 t C ha-1 yr-1. Net C uptake over the next 100-years increased by 22% or 0.33 t C ha-1 yr-1 relative to the current harvest rate in the study region under the optized harvest regime. Conclusions The forest’s biological ecosystem current and future carbon uptake capacity is largely determined by forest harvest practices that occurred over a century ago, but we show an optimized harvesting strategy would increase future carbon sequestration, or wood production, by 20-30%, reduce long transportation chain emissions, and maintain many desirable stand structural attributes that are correlated to biodiversity. Our results for this forest region suggest that increasing harvest over the next 100 years increases the strength of

  7. Estimating the carbon budget and maximizing future carbon uptake for a temperate forest region in the U.S.

    Directory of Open Access Journals (Sweden)

    Peckham Scott D

    2012-06-01

    Full Text Available Abstract Background Forests of the Midwest U.S. provide numerous ecosystem services. Two of these, carbon sequestration and wood production, are often portrayed as conflicting. Currently, carbon management and biofuel policies are being developed to reduce atmospheric CO2 and national dependence on foreign oil, and increase carbon storage in ecosystems. However, the biological and industrial forest carbon cycles are rarely studied in a whole-system structure. The forest system carbon balance is the difference between the biological (net ecosystem production and industrial (net emissions from forest industry forest carbon cycles, but to date this critical whole system analysis is lacking. This study presents a model of the forest system, uses it to compute the carbon balance, and outlines a methodology to maximize future carbon uptake in a managed forest region. Results We used a coupled forest ecosystem process and forest products life cycle inventory model for a regional temperate forest in the Midwestern U.S., and found the net system carbon balance for this 615,000 ha forest was positive (2.29 t C ha-1 yr-1. The industrial carbon budget was typically less than 10% of the biological system annually, and averaged averaged 0.082 t C ha-1 yr-1. Net C uptake over the next 100-years increased by 22% or 0.33 t C ha-1 yr-1 relative to the current harvest rate in the study region under the optized harvest regime. Conclusions The forest’s biological ecosystem current and future carbon uptake capacity is largely determined by forest harvest practices that occurred over a century ago, but we show an optimized harvesting strategy would increase future carbon sequestration, or wood production, by 20-30%, reduce long transportation chain emissions, and maintain many desirable stand structural attributes that are correlated to biodiversity. Our results for this forest region suggest that increasing harvest over the next 100

  8. Biocide Selective TolC-Independent Efflux Pumps in Enterobacteriaceae.

    Science.gov (United States)

    Slipski, Carmine J; Zhanel, George G; Bay, Denice C

    2018-02-01

    Bacterial resistance to biocides used as antiseptics, dyes, and disinfectants is a growing concern in food preparation, agricultural, consumer manufacturing, and health care industries, particularly among Gram-negative Enterobacteriaceae, some of the most common community and healthcare-acquired bacterial pathogens. Biocide resistance is frequently associated with antimicrobial cross-resistance leading to reduced activity and efficacy of both antimicrobials and antiseptics. Multidrug resistant efflux pumps represent an important biocide resistance mechanism in Enterobacteriaceae. An assortment of structurally diverse efflux pumps frequently co-exist in these species and confer both unique and overlapping biocide and antimicrobial selectivity. TolC-dependent multicomponent systems that span both the plasma and outer membranes have been shown to confer clinically significant resistance to most antimicrobials including many biocides, however, a growing number of single component TolC-independent multidrug resistant efflux pumps are specifically associated with biocide resistance: small multidrug resistance (SMR), major facilitator superfamily (MFS), multidrug and toxin extruder (MATE), cation diffusion facilitator (CDF), and proteobacterial antimicrobial compound efflux (PACE) families. These efflux systems are a growing concern as they are rapidly spread between members of Enterobacteriaceae on conjugative plasmids and mobile genetic elements, emphasizing their importance to antimicrobial resistance. In this review, we will summarize the known biocide substrates of these efflux pumps, compare their structural relatedness, Enterobacteriaceae distribution, and significance. Knowledge gaps will be highlighted in an effort to unravel the role that these apparent "lone wolves" of the efflux-mediated resistome may offer.

  9. Bacterial multidrug efflux pumps: mechanisms, physiology and pharmacological exploitations.

    Science.gov (United States)

    Sun, Jingjing; Deng, Ziqing; Yan, Aixin

    2014-10-17

    Multidrug resistance (MDR) refers to the capability of bacterial pathogens to withstand lethal doses of structurally diverse drugs which are capable of eradicating non-resistant strains. MDR has been identified as a major threat to the public health of human being by the World Health Organization (WHO). Among the four general mechanisms that cause antibiotic resistance including target alteration, drug inactivation, decreased permeability and increased efflux, drug extrusion by the multidrug efflux pumps serves as an important mechanism of MDR. Efflux pumps not only can expel a broad range of antibiotics owing to their poly-substrate specificity, but also drive the acquisition of additional resistance mechanisms by lowering intracellular antibiotic concentration and promoting mutation accumulation. Over-expression of multidrug efflux pumps have been increasingly found to be associated with clinically relevant drug resistance. On the other hand, accumulating evidence has suggested that efflux pumps also have physiological functions in bacteria and their expression is subject tight regulation in response to various of environmental and physiological signals. A comprehensive understanding of the mechanisms of drug extrusion, and regulation and physiological functions of efflux pumps is essential for the development of anti-resistance interventions. In this review, we summarize the development of these research areas in the recent decades and present the pharmacological exploitation of efflux pump inhibitors as a promising anti-drug resistance intervention. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

  10. Bacterial Multidrug Efflux Pumps: Much More Than Antibiotic Resistance Determinants.

    Science.gov (United States)

    Blanco, Paula; Hernando-Amado, Sara; Reales-Calderon, Jose Antonio; Corona, Fernando; Lira, Felipe; Alcalde-Rico, Manuel; Bernardini, Alejandra; Sanchez, Maria Blanca; Martinez, Jose Luis

    2016-02-16

    Bacterial multidrug efflux pumps are antibiotic resistance determinants present in all microorganisms. With few exceptions, they are chromosomally encoded and present a conserved organization both at the genetic and at the protein levels. In addition, most, if not all, strains of a given bacterial species present the same chromosomally-encoded efflux pumps. Altogether this indicates that multidrug efflux pumps are ancient elements encoded in bacterial genomes long before the recent use of antibiotics for human and animal therapy. In this regard, it is worth mentioning that efflux pumps can extrude a wide range of substrates that include, besides antibiotics, heavy metals, organic pollutants, plant-produced compounds, quorum sensing signals or bacterial metabolites, among others. In the current review, we present information on the different functions that multidrug efflux pumps may have for the bacterial behaviour in different habitats as well as on their regulation by specific signals. Since, in addition to their function in non-clinical ecosystems, multidrug efflux pumps contribute to intrinsic, acquired, and phenotypic resistance of bacterial pathogens, the review also presents information on the search for inhibitors of multidrug efflux pumps, which are currently under development, in the aim of increasing the susceptibility of bacterial pathogens to antibiotics.

  11. ATP binding cassette G1-dependent cholesterol efflux during inflammation.

    Science.gov (United States)

    de Beer, Maria C; Ji, Ailing; Jahangiri, Anisa; Vaughan, Ashley M; de Beer, Frederick C; van der Westhuyzen, Deneys R; Webb, Nancy R

    2011-02-01

    ATP binding cassette transporter G1 (ABCG1) mediates the transport of cellular cholesterol to HDL, and it plays a key role in maintaining macrophage cholesterol homeostasis. During inflammation, HDL undergoes substantial remodeling, acquiring lipid changes and serum amyloid A (SAA) as a major apolipoprotein. In the current study, we investigated whether remodeling of HDL that occurs during acute inflammation impacts ABCG1-dependent efflux. Our data indicate that lipid free SAA acts similarly to apolipoprotein A-I (apoA-I) in mediating sequential efflux from ABCA1 and ABCG1. Compared with normal mouse HDL, acute phase (AP) mouse HDL containing SAA exhibited a modest but significant 17% increase in ABCG1-dependent efflux. Interestingly, AP HDL isolated from mice lacking SAA (SAAKO mice) was even more effective in promoting ABCG1 efflux. Hydrolysis with Group IIA secretory phospholipase A(2) (sPLA(2)-IIA) significantly reduced the ability of AP HDL from SAAKO mice to serve as a substrate for ABCG1-mediated cholesterol transfer, indicating that phospholipid (PL) enrichment, and not the presence of SAA, is responsible for alterations in efflux. AP human HDL, which is not PL-enriched, was somewhat less effective in mediating ABCG1-dependent efflux compared with normal human HDL. Our data indicate that inflammatory remodeling of HDL impacts ABCG1-dependent efflux independent of SAA.

  12. Comparison of regression coefficient and GIS-based methodologies for regional estimates of forest soil carbon stocks

    International Nuclear Information System (INIS)

    Elliott Campbell, J.; Moen, Jeremie C.; Ney, Richard A.; Schnoor, Jerald L.

    2008-01-01

    Estimates of forest soil organic carbon (SOC) have applications in carbon science, soil quality studies, carbon sequestration technologies, and carbon trading. Forest SOC has been modeled using a regression coefficient methodology that applies mean SOC densities (mass/area) to broad forest regions. A higher resolution model is based on an approach that employs a geographic information system (GIS) with soil databases and satellite-derived landcover images. Despite this advancement, the regression approach remains the basis of current state and federal level greenhouse gas inventories. Both approaches are analyzed in detail for Wisconsin forest soils from 1983 to 2001, applying rigorous error-fixing algorithms to soil databases. Resulting SOC stock estimates are 20% larger when determined using the GIS method rather than the regression approach. Average annual rates of increase in SOC stocks are 3.6 and 1.0 million metric tons of carbon per year for the GIS and regression approaches respectively. - Large differences in estimates of soil organic carbon stocks and annual changes in stocks for Wisconsin forestlands indicate a need for validation from forthcoming forest surveys

  13. Probabilistic estimates of 1.5-degree carbon budgets based on uncertainty in transient climate response and aerosol forcing

    Science.gov (United States)

    Partanen, A. I.; Mengis, N.; Jalbert, J.; Matthews, D.

    2017-12-01

    Nations agreed to limit the increase in global mean surface temperature relative to the preindustrial era below 2 degrees Celsius and pursue efforts to a more ambitious goal of 1.5 degrees Celsius. To achieve these goals, it is necessary to assess the amount of cumulative carbon emissions compatible with these temperature targets, i.e. so called carbon budgets. In this work, we use the intermediate complexity University of Victoria Earth System Climate Model (UVic ESCM) to assess how uncertainty in aerosol forcing and transient climate response transfers to uncertainty in future carbon budgets for burning fossil fuels. We create a perturbed parameter ensemble of model simulations by scaling aerosol forcing and transient climate response, and assess the likelihood of each simulation by comparing the simulated historical cumulative carbon emissions, CO2 concentration and radiative balance to observations. By weighting the results of each simulation with the likelihood of the simulation, the preliminary results give a carbon budget of 48 Pg C to reach 1.5 degree Celsius temperature increase. The small weighted mean is due to large fraction of simulations with strong aerosol forcing and transient climate response giving negative carbon budgets for this time period. The probability of the carbon budget being over 100 Pg C was 38% and 23% for over 200 Pg carbon budget. The carbon budgets after temperature stabilization at 1.5 degrees are even smaller with a weighted mean of -100 Pg C until the year 2200. The main reason for the negative carbon budgets after temperature stabilization is an assumed strong decrease in aerosol forcing in the 21st century. Conversely, simulations with weak aerosol forcing and transient climate response give positive carbon budgets. Our results highlight both the importance of reducing uncertainty in aerosol forcing and transient climate response, and of taking the non-CO2 forcers into account when estimating carbon budgets.

  14. How to estimate forest carbon for large areas from inventory data

    Science.gov (United States)

    James E. Smith; Linda S. Heath; Peter B. Woodbury

    2004-01-01

    Carbon sequestration through forest growth provides a low-cost approach for meeting state and national goals to reduce net accumulations of atmospheric carbon dioxide. Total forest ecosystem carbon stocks include "pools" in live trees, standing dead trees, understory vegetation, down dead wood, forest floor, and soil. Determining the level of carbon stocks in...

  15. Theoretical Estimation of Thermal Effects in Drilling of Woven Carbon Fiber Composite

    Directory of Open Access Journals (Sweden)

    José Díaz-Álvarez

    2014-06-01

    Full Text Available Carbon Fiber Reinforced Polymer (CFRPs composites are extensively used in structural applications due to their attractive properties. Although the components are usually made near net shape, machining processes are needed to achieve dimensional tolerance and assembly requirements. Drilling is a common operation required for further mechanical joining of the components. CFRPs are vulnerable to processing induced damage; mainly delamination, fiber pull-out, and thermal degradation, drilling induced defects being one of the main causes of component rejection during manufacturing processes. Despite the importance of analyzing thermal phenomena involved in the machining of composites, only few authors have focused their attention on this problem, most of them using an experimental approach. The temperature at the workpiece could affect surface quality of the component and its measurement during processing is difficult. The estimation of the amount of heat generated during drilling is important; however, numerical modeling of drilling processes involves a high computational cost. This paper presents a combined approach to thermal analysis of composite drilling, using both an analytical estimation of heat generated during drilling and numerical modeling for heat propagation. Promising results for indirect detection of risk of thermal damage, through the measurement of thrust force and cutting torque, are obtained.

  16. Top-down Estimates of Biomass Burning Emissions of Black Carbon in the Western United States

    Science.gov (United States)

    Mao, Y.; Li, Q.; Randerson, J. T.; CHEN, D.; Zhang, L.; Liou, K.

    2012-12-01

    We apply a Bayesian linear inversion to derive top-down estimates of biomass burning emissions of black carbon (BC) in the western United States (WUS) for May-November 2006 by inverting surface BC concentrations from the IMPROVE network using the GEOS-Chem chemical transport model. Model simulations are conducted at both 2°×2.5° (globally) and 0.5°×0.667° (nested over North America) horizontal resolutions. We first improve the spatial distributions and seasonal and interannual variations of the BC emissions from the Global Fire Emissions Database (GFEDv2) using MODIS 8-day active fire counts from 2005-2007. The GFEDv2 emissions in N. America are adjusted for three zones: boreal N. America, temperate N. America, and Mexico plus Central America. The resulting emissions are then used as a priori for the inversion. The a posteriori emissions are 2-5 times higher than the a priori in California and the Rockies. Model surface BC concentrations using the a posteriori estimate provide better agreement with IMPROVE observations (~50% increase in the Taylor skill score), including improved ability to capture the observed variability especially during June-September. However, model surface BC concentrations are still biased low by ~30%. Comparisons with the Fire Locating and Modeling of Burning Emissions (FLAMBE) are included.

  17. Estimating daily forest carbon fluxes using a combination of ground and remotely sensed data

    Science.gov (United States)

    Chirici, Gherardo; Chiesi, Marta; Corona, Piermaria; Salvati, Riccardo; Papale, Dario; Fibbi, Luca; Sirca, Costantino; Spano, Donatella; Duce, Pierpaolo; Marras, Serena; Matteucci, Giorgio; Cescatti, Alessandro; Maselli, Fabio

    2016-02-01

    Several studies have demonstrated that Monteith's approach can efficiently predict forest gross primary production (GPP), while the modeling of net ecosystem production (NEP) is more critical, requiring the additional simulation of forest respirations. The NEP of different forest ecosystems in Italy was currently simulated by the use of a remote sensing driven parametric model (modified C-Fix) and a biogeochemical model (BIOME-BGC). The outputs of the two models, which simulate forests in quasi-equilibrium conditions, are combined to estimate the carbon fluxes of actual conditions using information regarding the existing woody biomass. The estimates derived from the methodology have been tested against daily reference GPP and NEP data collected through the eddy correlation technique at five study sites in Italy. The first test concerned the theoretical validity of the simulation approach at both annual and daily time scales and was performed using optimal model drivers (i.e., collected or calibrated over the site measurements). Next, the test was repeated to assess the operational applicability of the methodology, which was driven by spatially extended data sets (i.e., data derived from existing wall-to-wall digital maps). A good estimation accuracy was generally obtained for GPP and NEP when using optimal model drivers. The use of spatially extended data sets worsens the accuracy to a varying degree, which is properly characterized. The model drivers with the most influence on the flux modeling strategy are, in increasing order of importance, forest type, soil features, meteorology, and forest woody biomass (growing stock volume).

  18. Estimating landscape-scale impacts of agricultural management on soil carbon using measurements and models

    Science.gov (United States)

    Schipanski, M.; Rosenzweig, S. T.; Robertson, A. D.; Sherrod, L. A.; Ghimire, R.; McMaster, G. S.

    2017-12-01

    Agriculture covers 40% of Earth's ice-free land area and has broad impacts on global biogeochemical cycles. While some agricultural management changes are small in scale or impact, others have the potential to shift biogeochemical cycles at landscape and larger scales if widely adopted. Understanding which management practices have the potential to contribute to climate change adaptation and mitigation while maintaining productivity requires scaling up estimates spatially and temporally. We used on-farm, long-term, and landscape scale datasets to estimate how crop rotations impact soil organic carbon (SOC) accumulation rates under current and future climate scenarios across the semi-arid Central and Southern Great Plains. We used a stratified, landscape-scale soil sampling approach across 96 farm fields to evaluate crop rotation intensity effects on SOC pools and pesticide inputs. Replacing traditional wheat-fallow rotations with more diverse, continuously cropped rotations increased SOC by 17% and 12% in 0-10 cm and 0-20 cm depths, respectively, and reduced herbicide use by 50%. Using USDA Cropland Data Layer, we estimated soil C accumulation and pesticide reduction potentials of shifting to more intensive rotations. We also used a 30-year cropping systems experiment to calibrate and validate the Daycent model to evaluate rotation intensify effects under future climate change scenarios. The model estimated greater SOC accumulation rates under continuously cropped rotations, but SOC stocks peaked and then declined for all cropping systems beyond 2050 under future climate scenarios. Perennial grasslands were the only system estimated to maintain SOC levels in the future. In the Southern High Plains, soil C declined despite increasing input intensity under current weather while modest gains were simulated under future climate for sorghum-based cropping systems. Our findings highlight the potential vulnerability of semi-arid regions to climate change, which will be

  19. Carbon Sequestration Estimation of Street Trees Based on Point Cloud from Vehicle-Borne Laser Scanning System

    Science.gov (United States)

    Zhao, Y.; Hu, Q.

    2017-09-01

    Continuous development of urban road traffic system requests higher standards of road ecological environment. Ecological benefits of street trees are getting more attention. Carbon sequestration of street trees refers to the carbon stocks of street trees, which can be a measurement for ecological benefits of street trees. Estimating carbon sequestration in a traditional way is costly and inefficient. In order to solve above problems, a carbon sequestration estimation approach for street trees based on 3D point cloud from vehicle-borne laser scanning system is proposed in this paper. The method can measure the geometric parameters of a street tree, including tree height, crown width, diameter at breast height (DBH), by processing and analyzing point cloud data of an individual tree. Four Chinese scholartree trees and four camphor trees are selected for experiment. The root mean square error (RMSE) of tree height is 0.11m for Chinese scholartree and 0.02m for camphor. Crown widths in X direction and Y direction, as well as the average crown width are calculated. And the RMSE of average crown width is 0.22m for Chinese scholartree and 0.10m for camphor. The last calculated parameter is DBH, the RMSE of DBH is 0.5cm for both Chinese scholartree and camphor. Combining the measured geometric parameters and an appropriate carbon sequestration calculation model, the individual tree's carbon sequestration will be estimated. The proposed method can help enlarge application range of vehicle-borne laser point cloud data, improve the efficiency of estimating carbon sequestration, construct urban ecological environment and manage landscape.

  20. Challenges for present and future estimates of anthropogenic carbon in the Indian Ocean

    Science.gov (United States)

    Goyet, C.; Touratier, F.

    One of the main challenges we face today is to determine the evolution of the penetration of anthropogenic CO2 into the Indian Ocean and its impacts on marine and human life. Anthropogenic CO2 reaches the ocean via air-sea interactions as well as riverine inputs. It is then stored in the ocean and follows the oceanic circulation. As the carbon dioxide from the atmosphere penetrates into the sea, it reacts with water and acidifies the ocean. Consequently, the whole marine ecosystem is perturbed, thus potentially affecting the food web, which has, in turn, a direct impact on seafood supply for humans. Naturally, this will mainly affect the growing number of people living in coastal areas. Although anthropogenic CO2 in the ocean is identical with natural CO2 and therefore cannot be detected alone, many approaches are available today to estimate it. Since most of the results of these methods are globally in agreement, here we chose one of these methods, the tracer using oxygen, total inorganic carbon, and total alkalinity (TrOCA) approach, to compute the 3-D distribution of the anthropogenic CO2 concentrations throughout the Indian Ocean. The results of this distribution clearly illustrate the contrast between the Arabian Sea and the Bay of Bengal. They further show the importance of the southern part of this ocean that carries some anthropogenic CO2 at great depths. In order to determine the future anthropogenic impacts on the Indian Ocean, it is urgent and necessary to understand the present state. As the seawater temperature increases, how and how fast will the ocean circulation change? What will the impacts on seawater properties be? Many people are living on the bordering coasts, how will they be affected?

  1. What causes differences between national estimates of forest management carbon emissions and removals compared to estimates of large - scale models?

    NARCIS (Netherlands)

    Groen, T.A.; Verkerk, P.J.; Böttcher, H.; Grassi, G.; Cienciala, E.; Black, K.G.; Fortin, M.; Köthke, M.; Lehtonen, A.; Nabuurs, G.J; Petrova, L.; Blujdea, V.

    2013-01-01

    Under the United Nations Framework Convention for Climate Change all Parties have to report on carbon emissions and removals from the forestry sector. Each Party can use its own approach and country specific data for this. Independently, large-scale models exist (e.g. EFISCEN and G4M as used in this

  2. Inactivation of Efflux Pumps Abolishes Bacterial Biofilm Formation

    DEFF Research Database (Denmark)

    Kvist, Malin; Hancock, Viktoria; Klemm, Per

    2008-01-01

    Bacterial biofilms cause numerous problems in health care and industry; notably, biofilms are associated with a large number of infections. Biofilm-dwelling bacteria are particularly resistant to antibiotics, making it hard to eradicate biofilm-associated infections. Bacteria rely on efflux pumps...... to get rid of toxic substances. We discovered that efflux pumps are highly active in bacterial biofilms, thus making efflux pumps attractive targets for antibiofilm measures. A number of efflux pump inhibitors (EPIs) are known. EPIs were shown to reduce biofilm formation, and in combination they could...... abolish biofilm formation completely. Also, EPIs were able to block the antibiotic tolerance of biofilms. The results of this feasibility study might pave the way for new treatments for biofilm-related infections and may be exploited for prevention of biofilms in general....

  3. A simplified, data-constrained approach to estimate the permafrost carbon-climate feedback.

    Science.gov (United States)

    Koven, C D; Schuur, E A G; Schädel, C; Bohn, T J; Burke, E J; Chen, G; Chen, X; Ciais, P; Grosse, G; Harden, J W; Hayes, D J; Hugelius, G; Jafarov, E E; Krinner, G; Kuhry, P; Lawrence, D M; MacDougall, A H; Marchenko, S S; McGuire, A D; Natali, S M; Nicolsky, D J; Olefeldt, D; Peng, S; Romanovsky, V E; Schaefer, K M; Strauss, J; Treat, C C; Turetsky, M

    2015-11-13

    We present an approach to estimate the feedback from large-scale thawing of permafrost soils using a simplified, data-constrained model that combines three elements: soil carbon (C) maps and profiles to identify the distribution and type of C in permafrost soils; incubation experiments to quantify the rates of C lost after thaw; and models of soil thermal dynamics in response to climate warming. We call the approach the Permafrost Carbon Network Incubation-Panarctic Thermal scaling approach (PInc-PanTher). The approach assumes that C stocks do not decompose at all when frozen, but once thawed follow set decomposition trajectories as a function of soil temperature. The trajectories are determined according to a three-pool decomposition model fitted to incubation data using parameters specific to soil horizon types. We calculate litterfall C inputs required to maintain steady-state C balance for the current climate, and hold those inputs constant. Soil temperatures are taken from the soil thermal modules of ecosystem model simulations forced by a common set of future climate change anomalies under two warming scenarios over the period 2010 to 2100. Under a medium warming scenario (RCP4.5), the approach projects permafrost soil C losses of 12.2-33.4 Pg C; under a high warming scenario (RCP8.5), the approach projects C losses of 27.9-112.6 Pg C. Projected C losses are roughly linearly proportional to global temperature changes across the two scenarios. These results indicate a global sensitivity of frozen soil C to climate change (γ sensitivity) of -14 to -19 Pg C °C(-1) on a 100 year time scale. For CH4 emissions, our approach assumes a fixed saturated area and that increases in CH4 emissions are related to increased heterotrophic respiration in anoxic soil, yielding CH4 emission increases of 7% and 35% for the RCP4.5 and RCP8.5 scenarios, respectively, which add an additional greenhouse gas forcing of approximately 10-18%. The simplified approach

  4. MIPAS ESA v7 carbon tetrachloride data: distribution, trend and atmospheric lifetime estimation

    Science.gov (United States)

    Valeri, M.; Barbara, F.; Boone, C. D.; Ceccherini, S.; Gai, M.; Maucher, G.; Raspollini, P.; Ridolfi, M.; Sgheri, L.; Wetzel, G.; Zoppetti, N.

    2017-12-01

    Carbon tetrachloride (CCl4) is a strong ozone-depleting atmospheric gas regulated by the Montreal protocol. Recently it received increasing interest due to the so called "mystery of CCl4": it was found that its atmospheric concentration at the surface declines with a rate significantly smaller than its lifetime-limited rate. Indeed there is a discrepancy between atmospheric observations and the estimated distribution based on the reported production and consumption. Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) measurements are used to estimate CCl4 distributions, its trend, and atmospheric lifetime in the upper troposphere / lower stratosphere (UTLS) region. In particular, here we use MIPAS product generated with Version 7 of the Level 2 algorithm operated by the European Space Agency. The CCl4 distribution shows features typical of long-lived species of anthropogenic origin: higher concentrations in the troposphere, decreasing with altitude due to the photolysis. We compare MIPAS CCl4 data with independent observations from Atmospheric Chemistry Experiment - Fourier Transform Spectrometer (ACE - FTS) and stratospheric balloon version of MIPAS (MIPAS-B). The comparison shows a general good agreement between the different datasets. CCl4 trends are evaluated as a function of both latitude and altitude: negative trends (-10/ -15 pptv/decade, -10/ -30 %/decade) are found at all latitudes in the UTLS, apart from a region in the Southern mid-latitudes between 50 and 10 hPa where the trend is slightly positive (5/10 pptv/decade, 15/20 %/decade). At the lowest altitudes sounded by the MIPAS scan we find trend values consistent with those determined on the basis of the Advanced Global Atmospheric Gases Experiment (AGAGE) and the National Oceanic and Atmospheric Administration / Earth System Research Laboratory / Halocarbons and other Atmospheric Trace Species (NOAA / ESRL / HATS) networks. CCl4 global average lifetime of 47(39 - 61) years has been

  5. Toward a consistency cross-check of eddy covariance flux-based and biometric estimates of ecosystem carbon balance

    NARCIS (Netherlands)

    Luyssaert, S.; Reichstein, M.; Schulze, E.D.; Janssens, I.A.; Law, B.E.; Papale, D.; Dragoni, D.; Goulden, M.L.; Granier, A.; Kutch, W.L.; Linder, S.; Matteucci, G.; Moors, E.J.; Munger, J.W.; Pilegaard, K.; Saunders, M.; Falge, E.M.

    2009-01-01

    Quantification of an ecosystem's carbon balance and its components is pivotal for understanding both ecosystem functioning and global cycling. Several methods are being applied in parallel to estimate the different components of the CO2 balance. However, different methods are subject to different

  6. Regional myocardial oxygen consumption estimated by carbon-11 acetate and positron emission tomography before and after repetitive ischemia

    DEFF Research Database (Denmark)

    Kofoed, K F; Hansen, P R; Holm, S

    2011-01-01

    Preserved myocardial oxygen consumption estimated by carbon 11-acetate and positron emission tomography (PET) in myocardial regions with chronic but reversibly depressed contractile function in patients with ischemic heart disease have been suggested to be caused by repeated short episodes of acu...

  7. Validity of estimating the organic carbon content of basin sediment using color measurements

    International Nuclear Information System (INIS)

    Sasaki, Toshinori; Sugai, Toshihiko; Ogami, Takashi; Yanagida, Makoto; Yasue, Ken-ichi

    2010-01-01

    Psychometric lightness (L* value) measured by a colorimeter offers a rapid means of obtaining the organic carbon content of sediment. We measured peat and lacustrine sediments covering the past 300 ka - 106 samples for L* value and 197 samples for organic carbon content. L* values are highly correlated with organic carbon contents. Therefore, L* values are a convenient alternative to measuring organic carbon contents. (author)

  8. Carbon accounting and cost estimation in forestry projects using CO2Fix V.3

    OpenAIRE

    Groen, T.A.; Nabuurs, G.J.; Schelhaas, M.J.

    2006-01-01

    Carbon and financial accounting of projects in the Land Use, Land-Use Change and Forestry sector is a topic of hot debate. Large uncertainty remains concerning the carbon dynamics, the way they should be accounted and the cost efficiency of the projects. Part of the uncertainty can be alleviated by standardisation and transparency of reporting methods. For this reason we further developed CO2FIX, a forest ecosystem carbon model, with modules for carbon and financial accounting. The model is a...

  9. Reliability of Carbon Stock Estimates in Imperata Grassland (East Kalimantan, Indonesia), Using Georeferenced Information

    NARCIS (Netherlands)

    Yassir, I.; Putten, van B.; Buurman, P.

    2012-01-01

    Knowledge of the spatial distribution of total carbon is important for understanding the impact of regional land use change on the global carbon cycle. We studied spatial total carbon variability using transect sampling in an Imperata grassland area. Spatial variability was modeled following an

  10. An estimated carbon footprint of NHS primary dental care within England. How can dentistry be more environmentally sustainable?

    Science.gov (United States)

    Duane, B; Lee, M Berners; White, S; Stancliffe, R; Steinbach, I

    2017-10-27

    Introduction National Health Service (NHS) England dental teams need to consider from a professional perspective how they can, along with their NHS colleagues, play their part in reducing their carbon emissions and improve the sustainability of the care they deliver. In order to help understand carbon emissions from dental services, Public Health England (PHE) commissioned a calculation and analysis of the carbon footprint of key dental procedures.Methods Secondary data analysis from Business Services Authority (BSA), Health and Social Care Information Centre (HSCIC) (now called NHS Digital, Information Services Division [ISD]), National Association of Specialist Dental Accountants (NASDA) and recent Scottish papers was undertaken using a process-based and environmental input-output analysis using industry established conversion factors.Results The carbon footprint of the NHS dental service is 675 kilotonnes carbon dioxide equivalents (CO2e). Examinations contributed the highest proportion to this footprint (27.1%) followed by scale and polish (13.4%) and amalgam/composite restorations (19.3%). From an emissions perspective, nearly 2/3 (64.5%) of emissions related to travel (staff and patient travel), 19% procurement (the products and services dental clinics buy) and 15.3% related to energy use.Discussion The results are estimates of carbon emissions based on a number of broad assumptions. More research, education and awareness is needed to help dentistry develop low carbon patient pathways.

  11. Estimation of pollutant source contribution to the Pampanga River Basin using carbon and nitrogen isotopes

    International Nuclear Information System (INIS)

    Castaneda, Solidad S.; Sta Maria, Efren J.; Ramirez, Jennyvi D.; Collado, Mario B.; Samar, Edna D.

    2013-01-01

    This study assessed and estimated the percentage contribution of potential pollution sources in Pampanga River Basin using carbon and nitrogen isotopes as environmental tracers. The δ 13 C and δ 15 N values were determined in particulate organic matter, surface sediment, and plant tissue samples from point and non-point sources from several land use areas, namely domestic, croplands, livestock, fishery and forestry. Investigations were conducted in the wet and dry seasons (2012 and 2013). Some N sources do not have unique δ 15 N and there is overlapping among different N- sources type. δ 13 C data from the N sources provided an additional dimension which distinguished animal manure, human waste (septic and sewage), leaf litter, and synthetic fertilizer. Characterization of the non-point N-sources based on the isotopic fingerprints obtained from the point sources revealed that domestic, cropland, livestock, and fishery, influenced the isotopic composition of the materials but domestic and cropland land use provided the most significant influence. Livestock also contributed to a lesser extent. Isotope mixing model revealed that cropland sources generally contributed the most to pollutant loading during the wet season, from 22% to 98%, while domestic waste contributed higher in the dry season, from 55% to 65%. (author)

  12. Carbon Footprint Estimation Tool for Residential Buildings for Non-Specialized Users: OERCO2 Project

    Directory of Open Access Journals (Sweden)

    Jaime Solís-Guzmán

    2018-04-01

    Full Text Available Existing tools for environmental certification of buildings are failing in their ability to reach the general public and to create social awareness, since they require not only specialized knowledge regarding construction and energy sources, but also environmental knowledge. In this paper, an open-source online tool for the estimation of the carbon footprint of residential buildings by non-specialized users is presented as a product from the OERCO2 Erasmus + project. The internal calculations, data management and operation of this tool are extensively explained. The ten most common building typologies built in the last decade in Spain are analysed by using the OERCO2 tool, and the order of magnitude of the results is analysed by comparing them to the ranges determined by other authors. The OERCO2 tool proves itself to be reliable, with its results falling within the defined logical value ranges. Moreover, the major simplification of the interface allows non-specialized users to evaluate the sustainability of buildings. Further research is oriented towards its inclusion in other environmental certification tools and in Building Information Modeling (BIM environments.

  13. Biomass burning losses of carbon estimated from ecosystem modeling and satellite data analysis for the Brazilian Amazon region

    Science.gov (United States)

    Potter, Christopher; Brooks Genovese, Vanessa; Klooster, Steven; Bobo, Matthew; Torregrosa, Alicia

    To produce a new daily record of gross carbon emissions from biomass burning events and post-burning decomposition fluxes in the states of the Brazilian Legal Amazon (Instituto Brasileiro de Geografia e Estatistica (IBGE), 1991. Anuario Estatistico do Brasil, Vol. 51. Rio de Janeiro, Brazil pp. 1-1024). We have used vegetation greenness estimates from satellite images as inputs to a terrestrial ecosystem production model. This carbon allocation model generates new estimates of regional aboveground vegetation biomass at 8-km resolution. The modeled biomass product is then combined for the first time with fire pixel counts from the advanced very high-resolution radiometer (AVHRR) to overlay regional burning activities in the Amazon. Results from our analysis indicate that carbon emission estimates from annual region-wide sources of deforestation and biomass burning in the early 1990s are apparently three to five times higher than reported in previous studies for the Brazilian Legal Amazon (Houghton et al., 2000. Nature 403, 301-304; Fearnside, 1997. Climatic Change 35, 321-360), i.e., studies which implied that the Legal Amazon region tends toward a net-zero annual source of terrestrial carbon. In contrast, our analysis implies that the total source fluxes over the entire Legal Amazon region range from 0.2 to 1.2 Pg C yr -1, depending strongly on annual rainfall patterns. The reasons for our higher burning emission estimates are (1) use of combustion fractions typically measured during Amazon forest burning events for computing carbon losses, (2) more detailed geographic distribution of vegetation biomass and daily fire activity for the region, and (3) inclusion of fire effects in extensive areas of the Legal Amazon covered by open woodland, secondary forests, savanna, and pasture vegetation. The total area of rainforest estimated annually to be deforested did not differ substantially among the previous analyses cited and our own.

  14. Soil carbon sequestration due to post-Soviet cropland abandonment: estimates from a large-scale soil organic carbon field inventory.

    Science.gov (United States)

    Wertebach, Tim-Martin; Hölzel, Norbert; Kämpf, Immo; Yurtaev, Andrey; Tupitsin, Sergey; Kiehl, Kathrin; Kamp, Johannes; Kleinebecker, Till

    2017-09-01

    The break-up of the Soviet Union in 1991 triggered cropland abandonment on a continental scale, which in turn led to carbon accumulation on abandoned land across Eurasia. Previous studies have estimated carbon accumulation rates across Russia based on large-scale modelling. Studies that assess carbon sequestration on abandoned land based on robust field sampling are rare. We investigated soil organic carbon (SOC) stocks using a randomized sampling design along a climatic gradient from forest steppe to Sub-Taiga in Western Siberia (Tyumen Province). In total, SOC contents were sampled on 470 plots across different soil and land-use types. The effect of land use on changes in SOC stock was evaluated, and carbon sequestration rates were calculated for different age stages of abandoned cropland. While land-use type had an effect on carbon accumulation in the topsoil (0-5 cm), no independent land-use effects were found for deeper SOC stocks. Topsoil carbon stocks of grasslands and forests were significantly higher than those of soils managed for crops and under abandoned cropland. SOC increased significantly with time since abandonment. The average carbon sequestration rate for soils of abandoned cropland was 0.66 Mg C ha -1  yr -1 (1-20 years old, 0-5 cm soil depth), which is at the lower end of published estimates for Russia and Siberia. There was a tendency towards SOC saturation on abandoned land as sequestration rates were much higher for recently abandoned (1-10 years old, 1.04 Mg C ha -1  yr -1 ) compared to earlier abandoned crop fields (11-20 years old, 0.26 Mg C ha -1  yr -1 ). Our study confirms the global significance of abandoned cropland in Russia for carbon sequestration. Our findings also suggest that robust regional surveys based on a large number of samples advance model-based continent-wide SOC prediction. © 2017 John Wiley & Sons Ltd.

  15. Sub-grid scale representation of vegetation in global land surface schemes: implications for estimation of the terrestrial carbon sink

    Directory of Open Access Journals (Sweden)

    J. R. Melton

    2014-02-01

    Full Text Available Terrestrial ecosystem models commonly represent vegetation in terms of plant functional types (PFTs and use their vegetation attributes in calculations of the energy and water balance as well as to investigate the terrestrial carbon cycle. Sub-grid scale variability of PFTs in these models is represented using different approaches with the "composite" and "mosaic" approaches being the two end-members. The impact of these two approaches on the global carbon balance has been investigated with the Canadian Terrestrial Ecosystem Model (CTEM v 1.2 coupled to the Canadian Land Surface Scheme (CLASS v 3.6. In the composite (single-tile approach, the vegetation attributes of different PFTs present in a grid cell are aggregated and used in calculations to determine the resulting physical environmental conditions (soil moisture, soil temperature, etc. that are common to all PFTs. In the mosaic (multi-tile approach, energy and water balance calculations are performed separately for each PFT tile and each tile's physical land surface environmental conditions evolve independently. Pre-industrial equilibrium CLASS-CTEM simulations yield global totals of vegetation biomass, net primary productivity, and soil carbon that compare reasonably well with observation-based estimates and differ by less than 5% between the mosaic and composite configurations. However, on a regional scale the two approaches can differ by > 30%, especially in areas with high heterogeneity in land cover. Simulations over the historical period (1959–2005 show different responses to evolving climate and carbon dioxide concentrations from the two approaches. The cumulative global terrestrial carbon sink estimated over the 1959–2005 period (excluding land use change (LUC effects differs by around 5% between the two approaches (96.3 and 101.3 Pg, for the mosaic and composite approaches, respectively and compares well with the observation-based estimate of 82.2 ± 35 Pg C over the same

  16. Audit of the global carbon budget: estimate errors and their impact on uptake uncertainty

    Science.gov (United States)

    Ballantyne, A. P.; Andres, R.; Houghton, R.; Stocker, B. D.; Wanninkhof, R.; Anderegg, W.; Cooper, L. A.; DeGrandpre, M.; Tans, P. P.; Miller, J. B.; Alden, C.; White, J. W. C.

    2015-04-01

    Over the last 5 decades monitoring systems have been developed to detect changes in the accumulation of carbon (C) in the atmosphere and ocean; however, our ability to detect changes in the behavior of the global C cycle is still hindered by measurement and estimate errors. Here we present a rigorous and flexible framework for assessing the temporal and spatial components of estimate errors and their impact on uncertainty in net C uptake by the biosphere. We present a novel approach for incorporating temporally correlated random error into the error structure of emission estimates. Based on this approach, we conclude that the 2σ uncertainties of the atmospheric growth rate have decreased from 1.2 Pg C yr-1 in the 1960s to 0.3 Pg C yr-1 in the 2000s due to an expansion of the atmospheric observation network. The 2σ uncertainties in fossil fuel emissions have increased from 0.3 Pg C yr-1 in the 1960s to almost 1.0 Pg C yr-1 during the 2000s due to differences in national reporting errors and differences in energy inventories. Lastly, while land use emissions have remained fairly constant, their errors still remain high and thus their global C uptake uncertainty is not trivial. Currently, the absolute errors in fossil fuel emissions rival the total emissions from land use, highlighting the extent to which fossil fuels dominate the global C budget. Because errors in the atmospheric growth rate have decreased faster than errors in total emissions have increased, a ~20% reduction in the overall uncertainty of net C global uptake has occurred. Given all the major sources of error in the global C budget that we could identify, we are 93% confident that terrestrial C uptake has increased and 97% confident that ocean C uptake has increased over the last 5 decades. Thus, it is clear that arguably one of the most vital ecosystem services currently provided by the biosphere is the continued removal of approximately half of atmospheric CO2 emissions from the atmosphere

  17. Estimation of Concrete Carbonation Depth Considering Multiple Influencing Factors on the Deterioration of Durability for Reinforced Concrete Structures

    Directory of Open Access Journals (Sweden)

    Hae-Chang Cho

    2016-01-01

    Full Text Available While the durability of concrete structures is greatly influenced by many factors, previous studies typically considered only a single durability deterioration factor. In addition, these studies mostly conducted their experiments inside the laboratory, and it is extremely hard to find any case in which data were obtained from field inspection. Accordingly, this study proposed an Adaptive Neurofuzzy Inference System (ANFIS algorithm that can estimate the carbonation depth of a reinforced concrete member, in which combined deterioration has been reflected based on the data obtained from field inspections of 9 buildings. The proposed ANFIS algorithm closely estimated the carbonation depths, and it is considered that, with further inspection data, a higher accuracy would be achieved. Thus, it is expected to be used very effectively for durability estimation of a building of which the inspection is performed periodically.

  18. Efflux as a mechanism of antimicrobial drug resistance in clinical relevant microorganisms: the role of efflux inhibitors.

    Science.gov (United States)

    Willers, Clarissa; Wentzel, Johannes Frederik; du Plessis, Lissinda Hester; Gouws, Chrisna; Hamman, Josias Hendrik

    2017-01-01

    Microbial resistance against antibiotics is a serious threat to the effective treatment of infectious diseases. Several mechanisms exist through which microorganisms can develop resistance against antimicrobial drugs, of which the overexpression of genes to produce efflux pumps is a major concern. Several efflux transporters have been identified in microorganisms, which infer resistance against specific antibiotics and even multidrug resistance. Areas covered: This paper focuses on microbial resistance against antibiotics by means of the mechanism of efflux and gives a critical overview of studies conducted to overcome this problem by combining efflux pump inhibitors with antibiotics. Information was obtained from a literature search done with MEDLINE, Pubmed, Scopus, ScienceDirect, OneSearch and EBSCO host. Expert opinion: Efflux as a mechanism of multidrug resistance has presented a platform for improved efficacy against resistant microorganisms by co-administration of efflux pump inhibitors with antimicrobial agents. Although proof of concept has been shown for this approach with in vitro experiments, further research is needed to develop more potent inhibitors with low toxicity which is clinically effective.

  19. Mapping and estimating the total living biomass and carbon in low-biomass woodlands using Landsat 8 CDR data

    Directory of Open Access Journals (Sweden)

    Belachew Gizachew

    2016-06-01

    Full Text Available Abstract Background A functional forest carbon measuring, reporting and verification (MRV system to support climate change mitigation policies, such as REDD+, requires estimates of forest biomass carbon, as an input to estimate emissions. A combination of field inventory and remote sensing is expected to provide those data. By linking Landsat 8 and forest inventory data, we (1 developed linear mixed effects models for total living biomass (TLB estimation as a function of spectral variables, (2 developed a 30 m resolution map of the total living carbon (TLC, and (3 estimated the total TLB stock of the study area. Inventory data consisted of tree measurements from 500 plots in 63 clusters in a 15,700 km2 study area, in miombo woodlands of Tanzania. The Landsat 8 data comprised two climate data record images covering the inventory area. Results We found a linear relationship between TLB and Landsat 8 derived spectral variables, and there was no clear evidence of spectral data saturation at higher biomass values. The root-mean-square error of the values predicted by the linear model linking the TLB and the normalized difference vegetation index (NDVI is equal to 44 t/ha (49 % of the mean value. The estimated TLB for the study area was 140 Mt, with a mean TLB density of 81 t/ha, and a 95 % confidence interval of 74–88 t/ha. We mapped the distribution of TLC of the study area using the TLB model, where TLC was estimated at 47 % of TLB. Conclusion The low biomass in the miombo woodlands, and the absence of a spectral data saturation problem suggested that Landsat 8 derived NDVI is suitable auxiliary information for carbon monitoring in the context of REDD+, for low-biomass, open-canopy woodlands.

  20. Modelling the Carbon Stocks Estimation of the Tropical Lowland Dipterocarp Forest Using LIDAR and Remotely Sensed Data

    Science.gov (United States)

    Zaki, N. A. M.; Latif, Z. A.; Suratman, M. N.; Zainal, M. Z.

    2016-06-01

    Tropical forest embraces a large stock of carbon in the global carbon cycle and contributes to the enormous amount of above and below ground biomass. The carbon kept in the aboveground living biomass of trees is typically the largest pool and the most directly impacted by the anthropogenic factor such as deforestation and forest degradation. However, fewer studies had been proposed to model the carbon for tropical rain forest and the quantification still remain uncertainties. A multiple linear regression (MLR) is one of the methods to define the relationship between the field inventory measurements and the statistical extracted from the remotely sensed data which is LiDAR and WorldView-3 imagery (WV-3). This paper highlight the model development from fusion of multispectral WV-3 with the LIDAR metrics to model the carbon estimation of the tropical lowland Dipterocarp forest of the study area. The result shown the over segmentation and under segmentation value for this output is 0.19 and 0.11 respectively, thus D-value for the classification is 0.19 which is 81%. Overall, this study produce a significant correlation coefficient (r) between Crown projection area (CPA) and Carbon stocks (CS); height from LiDAR (H_LDR) and Carbon stocks (CS); and Crown projection area (CPA) and height from LiDAR (H_LDR) were shown 0.671, 0.709 and 0.549 respectively. The CPA of the segmentation found to be representative spatially with higher correlation of relationship between diameter at the breast height (DBH) and carbon stocks which is Pearson Correlation p = 0.000 (p using multiple linear regression method. The study concluded that the integration of WV-3 imagery with the CHM raster based LiDAR were useful in order to quantify the AGB and carbon stocks for a larger sample area of the Lowland Dipterocarp forest.

  1. Factors controlling shell carbon isotopic composition of land snail Acusta despecta sieboldiana estimated from lab culturing experiment

    Science.gov (United States)

    Zhang, N.; Yamada, K.; Suzuki, N.; Yoshida, N.

    2014-05-01

    The carbon isotopic composition (δ13C) of land snail shell carbonate derives from three potential sources: diet, atmospheric CO2, and ingested carbonate (limestone). However, their relative contributions remain unclear. Under various environmental conditions, we cultured one land snail species, Acusta despecta sieboldiana collected from Yokohama, Japan, and confirmed that all of these sources affect shell carbonate δ13C values. Herein, we consider the influences of metabolic rates and temperature on the carbon isotopic composition of the shell carbonate. Based on previous works and on results obtained in this study, a simple but credible framework is presented for discussion of how each source and environmental parameter can affect shell carbonate δ13C values. According to this framework and some reasonable assumptions, we have estimated the contributions of different carbon sources for each snail individual: for cabbage (C3 plant) fed groups, the contributions of diet, atmospheric CO2 and ingested limestone respectively vary as 66-80%, 16-24%, and 0-13%. For corn (C4 plant) fed groups, because of the possible food stress (lower consumption ability of C4 plant), the values vary respectively as 56-64%, 18-20%, and 16-26%. Moreover, we present new evidence that snails have discrimination to choose C3 and C4 plants as food. Therefore, we suggest that food preferences must be considered adequately when applying δ13C in paleo-environment studies. Finally, we inferred that, during egg laying and hatching of our cultured snails, carbon isotope fractionation is controlled only by the isotopic exchange of the calcite-HCO3--aragonite equilibrium.

  2. Factors controlling shell carbon isotopic composition of land snail Acusta despecta sieboldiana estimated from laboratory culturing experiment

    Science.gov (United States)

    Zhang, N.; Yamada, K.; Suzuki, N.; Yoshida, N.

    2014-10-01

    The carbon isotopic composition (δ13C) of land snail shell carbonate derives from three potential sources: diet, atmospheric CO2, and ingested carbonate (limestone). However, their relative contributions remain unclear. Under various environmental conditions, we cultured one land snail subspecies, Acusta despecta sieboldiana, collected from Yokohama, Japan, and confirmed that all of these sources affect shell carbonate δ13C values. Herein, we consider the influences of metabolic rates and temperature on the carbon isotopic composition of the shell carbonate. Based on results obtained from previous works and this study, a simple but credible framework is presented to illustrate how each source and environmental parameter affects shell carbonate δ13C values. According to this framework and some reasonable assumptions, we estimated the contributions of different carbon sources for each snail individual: for cabbage-fed (C3 plant) groups, the contributions of diet, atmospheric CO2, and ingested limestone vary in the ranges of 66-80, 16-24, and 0-13%, respectively. For corn-fed (C4 plant) groups, because of the possible food stress (less ability to consume C4 plants), the values vary in the ranges of 56-64, 18-20, and 16-26%, respectively. Moreover, according to the literature and our observations, the subspecies we cultured in this study show preferences towards different plant species for food. Therefore, we suggest that the potential food preference should be considered adequately for some species in paleoenvironment studies. Finally, we inferred that only the isotopic exchange of the calcite-HCO3--aragonite equilibrium during egg laying and hatching of our cultured snails controls carbon isotope fractionation.

  3. Understanding the Effect of Land Cover Classification on Model Estimates of Regional Carbon Cycling in the Boreal Forest Biome

    Science.gov (United States)

    Kimball, John; Kang, Sinkyu

    2003-01-01

    The original objectives of this proposed 3-year project were to: 1) quantify the respective contributions of land cover and disturbance (i.e., wild fire) to uncertainty associated with regional carbon source/sink estimates produced by a variety of boreal ecosystem models; 2) identify the model processes responsible for differences in simulated carbon source/sink patterns for the boreal forest; 3) validate model outputs using tower and field- based estimates of NEP and NPP; and 4) recommend/prioritize improvements to boreal ecosystem carbon models, which will better constrain regional source/sink estimates for atmospheric C02. These original objectives were subsequently distilled to fit within the constraints of a 1 -year study. This revised study involved a regional model intercomparison over the BOREAS study region involving Biome-BGC, and TEM (A.D. McGuire, UAF) ecosystem models. The major focus of these revised activities involved quantifying the sensitivity of regional model predictions associated with land cover classification uncertainties. We also evaluated the individual and combined effects of historical fire activity, historical atmospheric CO2 concentrations, and climate change on carbon and water flux simulations within the BOREAS study region.

  4. Efflux Pump-mediated Drug Resistance in Burkholderia

    Directory of Open Access Journals (Sweden)

    Nicole L Podnecky

    2015-04-01

    Full Text Available Several members of the genus Burkholderia are prominent pathogens. Infections caused by these bacteria are difficult to treat because of significant antibiotic resistance. Virtually all Burkholderia species are also resistant to polymyxin, prohibiting use of drugs like colistin that are available for treatment of infections caused by most other drug resistant Gram-negative bacteria. Despite clinical significance and antibiotic resistance of Burkholderia species, characterization of efflux pumps lags behind other non-enteric Gram-negative pathogens such as Acinetobacter baumannii and Pseudomonas aeruginosa. Although efflux pumps have been described in several Burkholderia species, they have been best studied in B. cenocepacia and B. pseudomallei. As in other non-enteric Gram-negatives, efflux pumps of the resistance nodulation cell division (RND family are the clinically most significant efflux systems in these two species. Several efflux pumps were described in B. cenocepacia, which when expressed confer resistance to clinically significant antibiotics, including aminoglycosides, chloramphenicol, fluoroquinolones, and tetracyclines. Three RND pumps have been characterized in B. pseudomallei, two of which confer either intrinsic or acquired resistance to aminoglycosides, macrolides, chloramphenicol, fluoroquinolones, tetracyclines, trimethoprim, and in some instances trimethoprim+sulfamethoxazole. Several strains of the host-adapted B. mallei, a clone of B. pseudomallei, lack AmrAB-OprA and are therefore aminoglycoside and macrolide susceptible. B. thailandensis is closely related to B. pseudomallei, but non-pathogenic to humans. Its pump repertoire and ensuing drug resistance profile parallels that of B. pseudomallei. An efflux pump in B. vietnamiensis plays a significant role in acquired aminoglycoside resistance. Summarily, efflux pumps are significant players in Burkholderia drug resistance.

  5. Provincial carbon intensity abatement potential estimation in China: A PSO–GA-optimized multi-factor environmental learning curve method

    International Nuclear Information System (INIS)

    Yu, Shiwei; Zhang, Junjie; Zheng, Shuhong; Sun, Han

    2015-01-01

    This study aims to estimate carbon intensity abatement potential in China at the regional level by proposing a particle swarm optimization–genetic algorithm (PSO–GA) multivariate environmental learning curve estimation method. The model uses two independent variables, namely, per capita gross domestic product (GDP) and the proportion of the tertiary industry in GDP, to construct carbon intensity learning curves (CILCs), i.e., CO 2 emissions per unit of GDP, of 30 provinces in China. Instead of the traditional ordinary least squares (OLS) method, a PSO–GA intelligent optimization algorithm is used to optimize the coefficients of a learning curve. The carbon intensity abatement potentials of the 30 Chinese provinces are estimated via PSO–GA under the business-as-usual scenario. The estimation reveals the following results. (1) For most provinces, the abatement potentials from improving a unit of the proportion of the tertiary industry in GDP are higher than the potentials from raising a unit of per capita GDP. (2) The average potential of the 30 provinces in 2020 will be 37.6% based on the emission's level of 2005. The potentials of Jiangsu, Tianjin, Shandong, Beijing, and Heilongjiang are over 60%. Ningxia is the only province without intensity abatement potential. (3) The total carbon intensity in China weighted by the GDP shares of the 30 provinces will decline by 39.4% in 2020 compared with that in 2005. This intensity cannot achieve the 40%–45% carbon intensity reduction target set by the Chinese government. Additional mitigation policies should be developed to uncover the potentials of Ningxia and Inner Mongolia. In addition, the simulation accuracy of the CILCs optimized by PSO–GA is higher than that of the CILCs optimized by the traditional OLS method. - Highlights: • A PSO–GA-optimized multi-factor environmental learning curve method is proposed. • The carbon intensity abatement potentials of the 30 Chinese provinces are estimated by

  6. Cost Estimation and Comparison of Carbon Capture and Storage Technology with Wind Energy

    Directory of Open Access Journals (Sweden)

    ABDULLAH MENGAL

    2017-04-01

    Full Text Available The CCS (Carbon Capture and Storage is one of the significant solutions to reduce CO2 emissions from fossil fuelled electricity generation plants and minimize the effect of global warming. Economic analysis of CCS technology is, therefore, essential for the feasibility appraisal towards CO2 reduction. In this paper LCOE (Levelized Cost of Electricity Generation has been estimated with and without CCS technology for fossil fuel based power plants of Pakistan and also further compared with computed LCOE of WE (Wind Energy based power plants of the Pakistan. The results of this study suggest that the electricity generation costs of the fossil fuel power plants increase more than 44% with CCS technology as compared to without CCS technology. The generation costs are also found to be 10% further on higher side when considering efficiency penalty owing to installation of CCS technology. In addition, the CO2 avoided costs from natural gas plant are found to be 40 and 10% higher than the local coal and imported coal plants respectively. As such, the electricity generation cost of 5.09 Rs/kWh from WE plants is found to be competitive even when fossil fuel based plants are without CCS technology, with lowest cost of 5.9 Rs./kWh of CCNG (Combined Cycle Natural Gas plant. Based on analysis of results of this study and anticipated future development of efficient and cheap WE technologies, it is concluded that WE based electricity generation would be most appropriate option for CO2 reduction for Pakistan.

  7. MODELLING THE CARBON STOCKS ESTIMATION OF THE TROPICAL LOWLAND DIPTEROCARP FOREST USING LIDAR AND REMOTELY SENSED DATA

    Directory of Open Access Journals (Sweden)

    N. A. M. Zaki

    2016-06-01

    Full Text Available Tropical forest embraces a large stock of carbon in the global carbon cycle and contributes to the enormous amount of above and below ground biomass. The carbon kept in the aboveground living biomass of trees is typically the largest pool and the most directly impacted by the anthropogenic factor such as deforestation and forest degradation. However, fewer studies had been proposed to model the carbon for tropical rain forest and the quantification still remain uncertainties. A multiple linear regression (MLR is one of the methods to define the relationship between the field inventory measurements and the statistical extracted from the remotely sensed data which is LiDAR and WorldView-3 imagery (WV-3. This paper highlight the model development from fusion of multispectral WV-3 with the LIDAR metrics to model the carbon estimation of the tropical lowland Dipterocarp forest of the study area. The result shown the over segmentation and under segmentation value for this output is 0.19 and 0.11 respectively, thus D-value for the classification is 0.19 which is 81%. Overall, this study produce a significant correlation coefficient (r between Crown projection area (CPA and Carbon stocks (CS; height from LiDAR (H_LDR and Carbon stocks (CS; and Crown projection area (CPA and height from LiDAR (H_LDR were shown 0.671, 0.709 and 0.549 respectively. The CPA of the segmentation found to be representative spatially with higher correlation of relationship between diameter at the breast height (DBH and carbon stocks which is Pearson Correlation p = 0.000 (p Dipterocarp forest.

  8. Combining multiple ecosystem productivity measurements to constrain carbon uptake estimates in semiarid grasslands and shrublands

    Science.gov (United States)

    Maurer, G. E.; Krofcheck, D. J.; Collins, S. L.; Litvak, M. E.

    2016-12-01

    Recent observational and modeling studies have indicated that semiarid ecosystems are more dynamic contributors to the global carbon budget than once thought. Semiarid carbon fluxes, however, are generally small, with high interannual and spatial variability, which suggests that validating their global significance may depend on examining multiple productivity measures and their associated uncertainties and inconsistencies. We examined ecosystem productivity from eddy covariance (NEE), harvest (NPP), and terrestrial biome models (NEPm) at two very similar grassland sites and one creosote shrubland site in the Sevilleta National Wildlife Refuge of central New Mexico, USA. Our goal was to assess site and methodological correspondence in annual carbon uptake, patterns of interannual variability, and measurement uncertainty. One grassland site was a perennial carbon source losing 30 g C m-2 per year on average, while the other two sites were carbon sources or sinks depending on the year, with average net uptake of 5 and 25 g C m-2 per year at the grassland and shrubland site, respectively. Uncertainty values for cumulative annual NEE overlapped between the three sites in most years. When combined, aboveground and belowground annual NPP measurements were 15% higher than annual NEE values and did not confirm a loss of carbon at any site in any year. Despite differences in mean site carbon balance, year-to-year changes in cumulative annual NEE and NPP were similar at all sites with years 2010 and 2013 being favorable for carbon uptake and 2011 and 2012 being unfavorable at all sites. Modeled NEPm data for a number of nearby grid cells reproduced only a fraction of the observed range in carbon uptake and its interannual variability. These three sites are highly similar in location and climate and multiple carbon flux measurements confirm the high interannual variability in carbon flux. The exact magnitude of these fluxes, however, remains difficult to discern.

  9. Arsenic efflux from Microcystis aeruginosa under different phosphate regimes.

    Directory of Open Access Journals (Sweden)

    Changzhou Yan

    Full Text Available Phytoplankton plays an important role in arsenic speciation, distribution, and cycling in freshwater environments. Little information, however, is available on arsenic efflux from the cyanobacteria Microcystis aeruginosa under different phosphate regimes. This study investigated M. aeruginosa arsenic efflux and speciation by pre-exposing it to 10 µM arsenate or arsenite for 24 h during limited (12 h and extended (13 d depuration periods under phosphate enriched (+P and phosphate depleted (-P treatments. Arsenate was the predominant species detected in algal cells throughout the depuration period while arsenite only accounted for no greater than 45% of intracellular arsenic. During the limited depuration period, arsenic efflux occurred rapidly and only arsenate was detected in solutions. During the extended depuration period, however, arsenate and dimethylarsinic acid (DMA were found to be the two predominant arsenic species detected in solutions under -P treatments, but arsenate was the only species detected under +P treatments. Experimental results also suggest that phosphorus has a significant effect in accelerating arsenic efflux and promoting arsenite bio-oxidation in M. aeruginosa. Furthermore, phosphorus depletion can reduce arsenic efflux from algal cells as well as accelerate arsenic reduction and methylation. These findings can contribute to our understanding of arsenic biogeochemistry in aquatic environments and its potential environmental risks under different phosphorus levels.

  10. Multidrug Efflux Pumps in Staphylococcus aureus: an Update

    Science.gov (United States)

    Costa, Sofia Santos; Viveiros, Miguel; Amaral, Leonard; Couto, Isabel

    2013-01-01

    The emergence of infections caused by multi- or pan-resistant bacteria in the hospital or in the community settings is an increasing health concern. Albeit there is no single resistance mechanism behind multiresistance, multidrug efflux pumps, proteins that cells use to detoxify from noxious compounds, seem to play a key role in the emergence of these multidrug resistant (MDR) bacteria. During the last decades, experimental data has established their contribution to low level resistance to antimicrobials in bacteria and their potential role in the appearance of MDR phenotypes, by the extrusion of multiple, unrelated compounds. Recent studies suggest that efflux pumps may be used by the cell as a first-line defense mechanism, avoiding the drug to reach lethal concentrations, until a stable, more efficient alteration occurs, that allows survival in the presence of that agent. In this paper we review the current knowledge on MDR efflux pumps and their intricate regulatory network in Staphylococcus aureus, a major pathogen, responsible from mild to life-threatening infections. Particular emphasis will be given to the potential role that S. aureus MDR efflux pumps, either chromosomal or plasmid-encoded, have on resistance towards different antimicrobial agents and on the selection of drug - resistant strains. We will also discuss the many questions that still remain on the role of each specific efflux pump and the need to establish appropriate methodological approaches to address all these questions. PMID:23569469

  11. Multidrug Efflux Pumps in Staphylococcus aureus: an Update.

    Science.gov (United States)

    Costa, Sofia Santos; Viveiros, Miguel; Amaral, Leonard; Couto, Isabel

    2013-01-01

    The emergence of infections caused by multi- or pan-resistant bacteria in the hospital or in the community settings is an increasing health concern. Albeit there is no single resistance mechanism behind multiresistance, multidrug efflux pumps, proteins that cells use to detoxify from noxious compounds, seem to play a key role in the emergence of these multidrug resistant (MDR) bacteria. During the last decades, experimental data has established their contribution to low level resistance to antimicrobials in bacteria and their potential role in the appearance of MDR phenotypes, by the extrusion of multiple, unrelated compounds. Recent studies suggest that efflux pumps may be used by the cell as a first-line defense mechanism, avoiding the drug to reach lethal concentrations, until a stable, more efficient alteration occurs, that allows survival in the presence of that agent. In this paper we review the current knowledge on MDR efflux pumps and their intricate regulatory network in Staphylococcus aureus, a major pathogen, responsible from mild to life-threatening infections. Particular emphasis will be given to the potential role that S. aureus MDR efflux pumps, either chromosomal or plasmid-encoded, have on resistance towards different antimicrobial agents and on the selection of drug - resistant strains. We will also discuss the many questions that still remain on the role of each specific efflux pump and the need to establish appropriate methodological approaches to address all these questions.

  12. Estimates of Carbon Reservoirs in High-Altitude Wetlands in the Colombian Andes

    Directory of Open Access Journals (Sweden)

    Enrique Javier Peña

    2009-10-01

    Full Text Available The observed increase in emission of greenhouse gases, with attendant effects on global warming, have raised interests in identifying sources and sinks of carbon in the environment. Terrestrial carbon (C sequestration involves capture of atmospheric C through photosynthesis and storage in biota, soil and wetlands. Particularly, wetland systems function primarily as long-term reservoirs for atmospheric carbon dioxide (CO2 and as sources of atmospheric methane (CH4. The objective of this study was to evaluate the patterns of carbon reservoirs in two high-altitude wetlands in the central Andean mountain of Colombia. Carbon cycle in both systems is related mainly with the plant biomass dynamics from the littoral zone. Thus, total organic carbon concentrate an average up to 329 kg of N ha-1 and 125 kg of P ha-1 every year vs only 17 kg N ha-1 and 6 kg P ha-1 in the water column of the limnetic zone in the wetland, evidencing spatial differences in carbon concentrations for these types of ecosystems. Results revealed that these systems participate in the balance and sequestration of carbon in the Colombian Andes.

  13. Estimating the Contribution of Industry Structure Adjustment to the Carbon Intensity Target: A Case of Guangdong

    Directory of Open Access Journals (Sweden)

    Ping Wang

    2016-04-01

    Full Text Available Industry structure adjustment is an effective measure to achieve the carbon intensity target of Guangdong Province. Accurately evaluating the contribution of industry structure adjustment to the carbon intensity target is helpful for the government to implement more flexible and effective policies and measures for CO2 emissions reduction. In this paper, we attempt to evaluate the contribution of industry structure adjustment to the carbon intensity target. Firstly, we predict the gross domestic product (GDP with scenario forecasting, industry structure with the Markov chain model, CO2 emissions with a novel correlation mode based on least squares support vector machine, and then we assess the contribution of industry structure adjustment to the carbon intensity target of Guangdong during the period of 2011–2015 under nine scenarios. The obtained results show, in the ideal scenario, that the economy will grow at a high speed and the industry structure will be significantly adjusted, and thus the carbon intensity in 2015 will decrease by 25.53% compared to that in 2010, which will make a 130.94% contribution to the carbon intensity target. Meanwhile, in the conservative scenario, the economy will grow at a low speed and the industry structure will be slightly adjusted, and thus the carbon intensity in 2015 will decrease by 23.89% compared to that in 2010, which will make a 122.50% contribution to the carbon intensity target.

  14. A Spatio-Temporal Based Estimation of Sequestered Carbon in the ...

    African Journals Online (AJOL)

    Michael

    2015-06-01

    Jun 1, 2015 ... reduction in carbon emissions due to deforestation and forest ... global initiatives to reduce global warming, and the management of ... using a process-based equilibrium terrestrial. *Manuscript ..... aboveground biomass limits modeled for African lowland ... replacement of vegetation biomass carbon from.

  15. Carbon accounting and cost estimation in forestry projects using CO2Fix V.3

    NARCIS (Netherlands)

    Groen, T.A.; Nabuurs, G.J.; Schelhaas, M.J.

    2006-01-01

    Carbon and financial accounting of projects in the Land Use, Land-Use Change and Forestry sector is a topic of hot debate. Large uncertainty remains concerning the carbon dynamics, the way they should be accounted and the cost efficiency of the projects. Part of the uncertainty can be alleviated by

  16. Compatible above-ground biomass equations and carbon stock estimation for small diameter Turkish pine (Pinus brutia Ten.).

    Science.gov (United States)

    Sakici, Oytun Emre; Kucuk, Omer; Ashraf, Muhammad Irfan

    2018-04-15

    Small trees and saplings are important for forest management, carbon stock estimation, ecological modeling, and fire management planning. Turkish pine (Pinus brutia Ten.) is a common coniferous species and comprises 25.1% of total forest area of Turkey. Turkish pine is also important due to its flammable fuel characteristics. In this study, compatible above-ground biomass equations were developed to predict needle, branch, stem wood, and above-ground total biomass, and carbon stock assessment was also described for Turkish pine which is smaller than 8 cm diameter at breast height or shorter than breast height. Compatible biomass equations are useful for biomass prediction of small diameter individuals of Turkish pine. These equations will also be helpful in determining fire behavior characteristics and calculating their carbon stock. Overall, present study will be useful for developing ecological models, forest management plans, silvicultural plans, and fire management plans.

  17. The reliability of grazing rate estimates from dilution experiments: Have we over-estimated rates of organic carbon consumption by microzooplankton?

    Directory of Open Access Journals (Sweden)

    J. R. Dolan,

    2005-01-01

    Full Text Available According to a recent global analysis, microzooplankton grazing is surprisingly invariant, ranging only between 59 and 74% of phytoplankton primary production across systems differing in seasonality, trophic status, latitude, or salinity. Thus an important biological process in the world ocean, the daily consumption of recently fixed carbon, appears nearly constant. We believe this conclusion is an artefact because dilution experiments are 1 prone to providing over-estimates of grazing rates and 2 unlikely to furnish evidence of low grazing rates. In our view the overall average rate of microzooplankton grazing probably does not exceed 50% of primary production and may be even lower in oligotrophic systems.

  18. Biomass estimates of freshwater zooplankton from length-carbon regression equations

    Directory of Open Access Journals (Sweden)

    Patrizia COMOLI

    2000-02-01

    Full Text Available We present length/carbon regression equations of zooplankton species collected from Lake Maggiore (N. Italy during 1992. The results are discussed in terms of the environmental factors, e.g. food availability, predation, controlling biomass production of particle- feeders and predators in the pelagic system of lakes. The marked seasonality in the length-standardized carbon content of Daphnia, and its time-specific trend suggest that from spring onward food availability for Daphnia population may be regarded as a simple decay function. Seasonality does not affect the carbon content/unit length of the two predator Cladocera Leptodora kindtii and Bythotrephes longimanus. Predation is probably the most important regulating factor for the seasonal dynamics of their carbon biomass. The existence of a constant factor to convert the diameter of Conochilus colonies into carbon seems reasonable for an organism whose population comes on quickly and just as quickly disappears.

  19. Estimation of Community Land Model parameters for an improved assessment of net carbon fluxes at European sites

    Science.gov (United States)

    Post, Hanna; Vrugt, Jasper A.; Fox, Andrew; Vereecken, Harry; Hendricks Franssen, Harrie-Jan

    2017-03-01

    The Community Land Model (CLM) contains many parameters whose values are uncertain and thus require careful estimation for model application at individual sites. Here we used Bayesian inference with the DiffeRential Evolution Adaptive Metropolis (DREAM(zs)) algorithm to estimate eight CLM v.4.5 ecosystem parameters using 1 year records of half-hourly net ecosystem CO2 exchange (NEE) observations of four central European sites with different plant functional types (PFTs). The posterior CLM parameter distributions of each site were estimated per individual season and on a yearly basis. These estimates were then evaluated using NEE data from an independent evaluation period and data from "nearby" FLUXNET sites at 600 km distance to the original sites. Latent variables (multipliers) were used to treat explicitly uncertainty in the initial carbon-nitrogen pools. The posterior parameter estimates were superior to their default values in their ability to track and explain the measured NEE data of each site. The seasonal parameter values reduced with more than 50% (averaged over all sites) the bias in the simulated NEE values. The most consistent performance of CLM during the evaluation period was found for the posterior parameter values of the forest PFTs, and contrary to the C3-grass and C3-crop sites, the latent variables of the initial pools further enhanced the quality-of-fit. The carbon sink function of the forest PFTs significantly increased with the posterior parameter estimates. We thus conclude that land surface model predictions of carbon stocks and fluxes require careful consideration of uncertain ecological parameters and initial states.

  20. How Choice of Depth Horizon Influences the Estimated Spatial Patterns and Global Magnitude of Ocean Carbon Export Flux

    Science.gov (United States)

    Palevsky, Hilary I.; Doney, Scott C.

    2018-05-01

    Estimated rates and efficiency of ocean carbon export flux are sensitive to differences in the depth horizons used to define export, which often vary across methodological approaches. We evaluate sinking particulate organic carbon (POC) flux rates and efficiency (e-ratios) in a global earth system model, using a range of commonly used depth horizons: the seasonal mixed layer depth, the particle compensation depth, the base of the euphotic zone, a fixed depth horizon of 100 m, and the maximum annual mixed layer depth. Within this single dynamically consistent model framework, global POC flux rates vary by 30% and global e-ratios by 21% across different depth horizon choices. Zonal variability in POC flux and e-ratio also depends on the export depth horizon due to pronounced influence of deep winter mixing in subpolar regions. Efforts to reconcile conflicting estimates of export need to account for these systematic discrepancies created by differing depth horizon choices.

  1. A neural network-based estimate of the seasonal to inter-annual variability of the Atlantic Ocean carbon sink

    DEFF Research Database (Denmark)

    Landschützer, P.; Gruber, N.; Bakker, D.C.E.

    2013-01-01

    The Atlantic Ocean is one of the most important sinks for atmospheric carbon dioxide (CO2), but this sink is known to vary substantially in time. Here we use surface ocean CO2 observations to estimate this sink and the temporal variability from 1998 to 2007 in the Atlantic Ocean. We benefit from ......, leading to a substantial trend toward a stronger CO2 sink for the entire South Atlantic (–0.14 Pg C yr–1 decade–1). The Atlantic carbon sink varies relatively little on inter-annual time-scales (±0.04 Pg C yr–1; 1σ)......The Atlantic Ocean is one of the most important sinks for atmospheric carbon dioxide (CO2), but this sink is known to vary substantially in time. Here we use surface ocean CO2 observations to estimate this sink and the temporal variability from 1998 to 2007 in the Atlantic Ocean. We benefit from (i...... poleward of 40° N, but many other parts of the North Atlantic increased more slowly, resulting in a barely changing Atlantic carbon sink north of the equator (–0.007 Pg C yr–1 decade–1). Surface ocean pCO2 was also increasing less than that of the atmosphere over most of the Atlantic south of the equator...

  2. Comparison of carbon uptake estimates from forest inventory and Eddy-Covariance for a montane rainforest in central Sulawesi

    Science.gov (United States)

    Heimsch, Florian; Kreilein, Heiner; Rauf, Abdul; Knohl, Alexander

    2016-04-01

    Rainforests in general and montane rainforests in particular have rarely been studied over longer time periods. We aim to provide baseline information of a montane tropical forest's carbon uptake over time in order to quantify possible losses through land-use change. Thus we conducted a re-inventory of 22 10-year old forest inventory plots, giving us a rare opportunity to quantify carbon uptake over such a long time period by traditional methods. We discuss shortfalls of such techniques and why our estimate of 1.5 Mg/ha/a should be considered as the lower boundary and not the mean carbon uptake per year. At the same location as the inventory, CO2 fluxes were measured with the Eddy-Covariance technique. Measurements were conducted at 48m height with an LI 7500 open-path infrared gas analyser. We will compare carbon uptake estimates from these measurements to those of the more conventional inventory method and discuss, which factors are probably responsible for differences.

  3. Rapid efflux of Ca2+ from heart mitochondria in the presence of inorganic pyrophosphate.

    Science.gov (United States)

    Vercesi, A; Lehninger, A L

    1984-01-13

    Inorganic pyrophosphate (PPi) in the intracellular concentration range causes rapid efflux of Ca2+ from rat heart mitochondria oxidizing pyruvate + malate in a low Na+ medium. Half-maximal rates of Ca2+ efflux were given by 20 microM PPi. During and after PPi-stimulated Ca2+ efflux the mitochondria retain their structural integrity and complete respiratory control. Carboxyatractyloside inhibits PPi-stimulated Ca2+ efflux, indicating PPi must enter the matrix in order to promote Ca2+ efflux. Heart mitochondria have a much higher affinity for PPi uptake and PPi-induced Ca2+ efflux than liver mitochondria.

  4. Toward a consistency cross-check of eddy covariance flux–based and biometric estimates of ecosystem carbon balance

    DEFF Research Database (Denmark)

    Luyssaert, S.; Reichstein, M.; Schulze, E.-D.

    2009-01-01

    Quantification of an ecosystem's carbon balance and its components is pivotal for understanding both ecosystem functioning and global cycling. Several methods are being applied in parallel to estimate the different components of the CO2 balance. However, different methods are subject to different...... sources of error. Therefore, it is necessary that site level component estimates are cross-checked against each other before being reported. Here we present a two-step approach for testing the accuracy and consistency of eddy covariance–based gross primary production (GPP) and ecosystem respiration (Re...

  5. Top-down estimate of a large source of atmospheric carbon monoxide associated with fuel combustion in Asia

    Energy Technology Data Exchange (ETDEWEB)

    Kasibhatla, P.; Arellano, A.; Logan, J.A.; Palmer, P.I.; Novelli, P. [Duke University, Durham, NC (United States). Nicholas School of Environmental & Earth Science

    2002-10-01

    Deriving robust regional estimates of the sources of chemically and radiatively important gases and aerosols to the atmosphere is challenging. Using an inverse modeling methodology, it was found that the source of carbon monoxide from fossil-fuel and biofuel combustion in Asia during 1994 was 350-380 Tg yr{sup -1}, which is 110-140 Tg yr{sup -1} higher than bottom-up estimates derived using traditional inventory-based approaches. This discrepancy points to an important gap in our understanding of the human impact on atmospheric chemical composition.

  6. Use of a combined oxygen and carbon dioxide transcutaneous electrode in the estimation of gas exchange during exercise.

    OpenAIRE

    Sridhar, M K; Carter, R; Moran, F; Banham, S W

    1993-01-01

    BACKGROUND--Accurate and reliable measurement of gas exchange during exercise has traditionally involved arterial cannulation. Non-invasive devices to estimate arterial oxygen (O2) and carbon dioxide (CO2) tensions are now available. A method has been devised and evaluated for measuring gas exchange during exercise with a combined transcutaneous O2 and CO2 electrode. METHODS--Symptom limited exercise tests were carried out in 24 patients reporting effort intolerance and breathlessness. Exerci...

  7. Fuel treatment impacts on estimated wildfire carbon loss from forests in Montana, Oregon, California, and Arizona

    Science.gov (United States)

    Stephens, Scott L.; Boerner, Ralph E.J.; Maghaddas, Jason J.; Maghaddas, Emily E.Y.; Collins, Brandon M.; Dow, Christopher B.; Edminster, Carl; Fiedler, Carl E.; Fry, Danny L.; Hartsough, Bruce R.; Keeley, Jon E.; Knapp, Eric E.; McIver, James D.; Skinner, Carl N.; Youngblood, Andrew P.

    2012-01-01

    Using forests to sequester carbon in response to anthropogenically induced climate change is being considered across the globe. A recent U.S. executive order mandated that all federal agencies account for sequestration and emissions of greenhouse gases, highlighting the importance of understanding how forest carbon stocks are influenced by wildfire. This paper reports the effects of the most common forest fuel reduction treatments on carbon pools composed of live and dead biomass as well as potential wildfire emissions from six different sites in four western U.S. states. Additionally, we predict the median forest product life spans and uses of materials removed during mechanical treatments. Carbon loss from modeled wildfire-induced tree mortality was lowest in the mechanical plus prescribed fire treatments, followed by the prescribed fire-only treatments. Wildfire emissions varied from 10–80 Mg/ha and were lowest in the prescribed fire and mechanical followed by prescribed fire treatments at most sites. Mean biomass removals per site ranged from approximately 30–60 dry Mg/ha; the median lives of products in first use varied considerably (from 50 years). Our research suggests most of the benefits of increased fire resistance can be achieved with relatively small reductions in current carbon stocks. Retaining or growing larger trees also reduced the vulnerability of carbon loss from wildfire. In addition, modeled vulnerabilities to carbon losses and median forest product life spans varied considerably across our study sites, which could be used to help prioritize treatment implementation.

  8. RND multidrug efflux pumps: what are they good for?

    Science.gov (United States)

    Alvarez-Ortega, Carolina; Olivares, Jorge; Martínez, José L.

    2013-01-01

    Multidrug efflux pumps are chromosomally encoded genetic elements capable of mediating resistance to toxic compounds in several life forms. In bacteria, these elements are involved in intrinsic and acquired resistance to antibiotics. Unlike other well-known horizontally acquired antibiotic resistance determinants, genes encoding for multidrug efflux pumps belong to the core of bacterial genomes and thus have evolved over millions of years. The selective pressure stemming from the use of antibiotics to treat bacterial infections is relatively recent in evolutionary terms. Therefore, it is unlikely that these elements have evolved in response to antibiotics. In the last years, several studies have identified numerous functions for efflux pumps that go beyond antibiotic extrusion. In this review we present some examples of these functions that range from bacterial interactions with plant or animal hosts, to the detoxification of metabolic intermediates or the maintenance of cellular homeostasis. PMID:23386844

  9. Phagocytosis-induced /sup 45/calcium efflux in polymorphonuclear leucocytes

    Energy Technology Data Exchange (ETDEWEB)

    Barthelemy, A; Schell-Frederick, E [Brussels Univ. (Belgium). Institut de Recherche Interdisciplinaire; Paridaens, R [Brussels Univ. (Belgium). Faculte de Medicine

    1977-10-15

    The role of calcium ions in regulating the structure and function of non-muscle cells is a subject of intense study. Several lines of evidence that calcium may be essential in the function of polymorphonuclear leuocytes (PMNL) and an important control element in the process of phagocytosis. Direct studies of calcium distribution and fluxes have only recently been undertaken. To our knowledge, no report of calcium movements during normal phagocytosis has been published. In the context of an overall study of calcium dynamics in the PMNL, we report here initial studies on /sup 45/Ca efflux in prelabelled guinea pig PMNL. The results demonstrate the energy-dependence of resting calcium efflux and an increased efflux upon addition of phagocytic particles which is not dependent on particle internalization.

  10. Estimation and Uncertainty of Recent Carbon Accumulation and Vertical Accretion in Drained and Undrained Forested Peatlands of the Southeastern USA

    Science.gov (United States)

    Drexler, Judith Z.; Fuller, Christopher C.; Orlando, James; Salas, Antonia; Wurster, Frederic C.; Duberstein, Jamie A.

    2017-10-01

    The purpose of this study was to determine how drainage impacts carbon densities and recent rates (past 50 years) of vertical accretion and carbon accumulation in southeastern forested peatlands. We compared these parameters in drained maple-gum (MAPL), Atlantic white cedar (CDR), and pocosin (POC) communities in the Great Dismal Swamp National Wildlife Refuge (GDS) of Virginia/North Carolina and in an intact (undrained) CDR swamp in the Alligator River National Wildlife Refuge (AR) of North Carolina. Peat cores were analyzed for bulk density, percent organic carbon, and 137Cs and 210Pb. An uncertainty analysis of both 137Cs and 210Pb approaches was used to constrain error at least partially related to mobility of both radioisotopes. GDS peats had lower porosities (89.6% (SD = 1.71) versus 95.3% (0.18)) and higher carbon densities (0.082 (0.021) versus 0.037 (0.009) g C cm-3) than AR. Vertical accretion rates (0.10-0.56 cm yr-1) were used to estimate a time period of 84-362 years for reestablishment of peat lost during the 2011 Lateral West fire at the GDS. Carbon accumulation rates ranged from 51 to 389 g C m-2 yr-1 for all sites. In the drained (GDS) versus intact (AR) CDR sites, carbon accumulation rates were similar with 137Cs (87GDS versus 92AR g C m-2 yr-1) and somewhat less at the GDS than AR as determined with 210Pb (111GDS versus 159AR g C m-2 yr-1). Heightened productivity and high polyphenol content of peat may be responsible for similar rates of carbon accumulation in both drained and intact CDR peatlands.

  11. Improving estimation of tree carbon stocks by harvesting aboveground woody biomass within airborne LiDAR flight areas

    Science.gov (United States)

    Colgan, M.; Asner, G. P.; Swemmer, A. M.

    2011-12-01

    The accurate estimation of carbon stored in a tree is essential to accounting for the carbon emissions due to deforestation and degradation. Airborne LiDAR (Light Detection and Ranging) has been successful in estimating aboveground carbon density (ACD) by correlating airborne metrics, such as canopy height, to field-estimated biomass. This latter step is reliant on field allometry which is applied to forest inventory quantities, such as stem diameter and height, to predict the biomass of a given tree stem. Constructing such allometry is expensive, time consuming, and requires destructive sampling. Consequently, the sample sizes used to construct such allometry are often small, and the largest tree sampled is often much smaller than the largest in the forest population. The uncertainty resulting from these sampling errors can lead to severe biases when the allometry is applied to stems larger than those harvested to construct the allometry, which is then subsequently propagated to airborne ACD estimates. The Kruger National Park (KNP) mission of maintaining biodiversity coincides with preserving ecosystem carbon stocks. However, one hurdle to accurately quantifying carbon density in savannas is that small stems are typically harvested to construct woody biomass allometry, yet they are not representative of Kruger's distribution of biomass. Consequently, these equations inadequately capture large tree variation in sapwood/hardwood composition, root/shoot/leaf allocation, branch fall, and stem rot. This study eliminates the "middleman" of field allometry by directly measuring, or harvesting, tree biomass within the extent of airborne LiDAR. This enables comparisons of field and airborne ACD estimates, and also enables creation of new airborne algorithms to estimate biomass at the scale of individual trees. A field campaign was conducted at Pompey Silica Mine 5km outside Kruger National Park, South Africa, in Mar-Aug 2010 to harvest and weigh tree mass. Since

  12. Climate change mitigation opportunities based on carbon footprint estimates of dietary patterns in Peru.

    Directory of Open Access Journals (Sweden)

    Ian Vázquez-Rowe

    Full Text Available Food consumption accounts for an important proportion of the world GHG emissions per capita. Previous studies have delved into the nature of dietary patterns, showing that GHG reductions can be achieved in diets if certain foods are consumed rather than other, more GHG intensive products. For instance, vegetarian and low-meat diets have proved to be less carbon intensive than diets that are based on ruminant meat. These environmental patterns, increasingly analyzed in developed nations, are yet to be assessed in countries liked Peru where food purchase represents a relatively high percentage of the average household expenditure, ranging from 38% to 51% of the same. Therefore, food consumption can be identified as a potential way to reduce GHG emissions in Peru. However, the Peruvian government lacks a specific strategy to mitigate emissions in this sector, despite the recent ratification of the Paris Accord. In view of this, the main objective of this study is to analyze the environmental impacts of a set of 47 Peruvian food diet profiles, including geographical and socioeconomic scenarios. In order to do this, Life Cycle Assessment was used as the methodological framework to obtain the overall impacts of the components in the dietary patterns observed and primary data linked to the composition of diets were collected from the Peruvian National Institute for Statistics (INEI. Life cycle inventories for the different products that are part of the Peruvian diet were obtained from a set of previous scientific articles and reports regarding food production. Results were computed using the IPCC 2013 assessment method to estimate GHG emissions. Despite variations in GHG emissions from a geographical perspective, no significant differences were observed between cities located in the three Peruvian natural regions (i.e., coast, Andes and Amazon basin. In contrast, there appears to be a strong, positive correlation between GHG emissions and social

  13. Climate change mitigation opportunities based on carbon footprint estimates of dietary patterns in Peru.

    Science.gov (United States)

    Vázquez-Rowe, Ian; Larrea-Gallegos, Gustavo; Villanueva-Rey, Pedro; Gilardino, Alessandro

    2017-01-01

    Food consumption accounts for an important proportion of the world GHG emissions per capita. Previous studies have delved into the nature of dietary patterns, showing that GHG reductions can be achieved in diets if certain foods are consumed rather than other, more GHG intensive products. For instance, vegetarian and low-meat diets have proved to be less carbon intensive than diets that are based on ruminant meat. These environmental patterns, increasingly analyzed in developed nations, are yet to be assessed in countries liked Peru where food purchase represents a relatively high percentage of the average household expenditure, ranging from 38% to 51% of the same. Therefore, food consumption can be identified as a potential way to reduce GHG emissions in Peru. However, the Peruvian government lacks a specific strategy to mitigate emissions in this sector, despite the recent ratification of the Paris Accord. In view of this, the main objective of this study is to analyze the environmental impacts of a set of 47 Peruvian food diet profiles, including geographical and socioeconomic scenarios. In order to do this, Life Cycle Assessment was used as the methodological framework to obtain the overall impacts of the components in the dietary patterns observed and primary data linked to the composition of diets were collected from the Peruvian National Institute for Statistics (INEI). Life cycle inventories for the different products that are part of the Peruvian diet were obtained from a set of previous scientific articles and reports regarding food production. Results were computed using the IPCC 2013 assessment method to estimate GHG emissions. Despite variations in GHG emissions from a geographical perspective, no significant differences were observed between cities located in the three Peruvian natural regions (i.e., coast, Andes and Amazon basin). In contrast, there appears to be a strong, positive correlation between GHG emissions and social expenditure or academic

  14. Using CO2 Prophet to estimate recovery factors for carbon dioxide enhanced oil recovery

    Science.gov (United States)

    Attanasi, Emil D.

    2017-07-17

    IntroductionThe Oil and Gas Journal’s enhanced oil recovery (EOR) survey for 2014 (Koottungal, 2014) showed that gas injection is the most frequently applied method of EOR in the United States and that carbon dioxide (CO2 ) is the most commonly used injection fluid for miscible operations. The CO2-EOR process typically follows primary and secondary (waterflood) phases of oil reservoir development. The common objective of implementing a CO2-EOR program is to produce oil that remains after the economic limit of waterflood recovery is reached. Under conditions of miscibility or multicontact miscibility, the injected CO2 partitions between the gas and liquid CO2 phases, swells the oil, and reduces the viscosity of the residual oil so that the lighter fractions of the oil vaporize and mix with the CO2 gas phase (Teletzke and others, 2005). Miscibility occurs when the reservoir pressure is at least at the minimum miscibility pressure (MMP). The MMP depends, in turn, on oil composition, impurities of the CO2 injection stream, and reservoir temperature. At pressures below the MMP, component partitioning, oil swelling, and viscosity reduction occur, but the efficiency is increasingly reduced as the pressure falls farther below the MMP. CO2-EOR processes are applied at the reservoir level, where a reservoir is defined as an underground formation containing an individual and separate pool of producible hydrocarbons that is confined by impermeable rock or water barriers and is characterized by a single natural pressure system. A field may consist of a single reservoir or multiple reservoirs that are not in communication but which may be associated with or related to a single structural or stratigraphic feature (U.S. Energy Information Administration [EIA], 2000). The purpose of modeling the CO2-EOR process is discussed along with the potential CO2-EOR predictive models. The data demands of models and the scope of the assessments require tradeoffs between reservoir

  15. Seeing the Forest through the Trees: Citizen Scientists Provide Critical Data to Refine Aboveground Carbon Estimates in Restored Riparian Forests

    Science.gov (United States)

    Viers, J. H.

    2013-12-01

    Integrating citizen scientists into ecological informatics research can be difficult due to limited opportunities for meaningful engagement given vast data streams. This is particularly true for analysis of remotely sensed data, which are increasingly being used to quantify ecosystem services over space and time, and to understand how land uses deliver differing values to humans and thus inform choices about future human actions. Carbon storage and sequestration are such ecosystem services, and recent environmental policy advances in California (i.e., AB 32) have resulted in a nascent carbon market that is helping fuel the restoration of riparian forests in agricultural landscapes. Methods to inventory and monitor aboveground carbon for market accounting are increasingly relying on hyperspatial remotely sensed data, particularly the use of light detection and ranging (LiDAR) technologies, to estimate biomass. Because airborne discrete return LiDAR can inexpensively capture vegetation structural differences at high spatial resolution ( 1000 ha), its use is rapidly increasing, resulting in vast stores of point cloud and derived surface raster data. While established algorithms can quantify forest canopy structure efficiently, the highly complex nature of native riparian forests can result in highly uncertain estimates of biomass due to differences in composition (e.g., species richness, age class) and structure (e.g., stem density). This study presents the comparative results of standing carbon estimates refined with field data collected by citizen scientists at three different sites, each capturing a range of agricultural, remnant forest, and restored forest cover types. These citizen science data resolve uncertainty in composition and structure, and improve allometric scaling models of biomass and thus estimates of aboveground carbon. Results indicate that agricultural land and horticulturally restored riparian forests store similar amounts of aboveground carbon

  16. Estimating dust production rate of carbon-rich stars in the Small Magellanic Cloud

    Science.gov (United States)

    Nanni, A.; Marigo, P.; Groenewegen, M. A. T.; Aringer, B.; Pastorelli, G.; Rubele, S.; Girardi, L.; Bressan, A.; Bladh, S.

    We compute a grid of spectra describing dusty Circumstellar Envelopes of Thermally Pulsing Asymptotic Giant Branch carbon-rich stars by employing a physically grounded description for dust growth. The optical constants for carbon dust have been selected in order to reproduce simultaneously the most important color-color diagrams in the Near and Mid Infrared bands. We fit the Spectral Energy Distribution of ≈2000 carbon-rich in the Small Magellanic Cloud and we compute their total dust production rate. We compare our results with the ones in the literature. Different choices of the dust-to-gas ratio and outflow expansion velocity adopted in different works, yield, in some cases, a total dust budget about three times lower than the one derived from our scheme, with the same optical data set for carbon dust.

  17. Allometric Equations for Estimating Biomass and Carbon Stocks in the Temperate Forests of North-Western Mexico

    Directory of Open Access Journals (Sweden)

    Benedicto Vargas-Larreta

    2017-07-01

    Full Text Available This paper presents new equations for estimating above-ground biomass (AGB and biomass components of seventeen forest species in the temperate forests of northwestern Mexico. A data set corresponding to 1336 destructively sampled oak and pine trees was used to fit the models. The generalized method of moments was used to simultaneously fit systems of equations for biomass components and AGB, to ensure additivity. In addition, the carbon content of each tree component was calculated by the dry combustion method, in a TOC analyser. The results of cross-validation indicated that the fitted equations accounted for on average 91%, 82%, 83% and 76% of the observed variance in stem wood and stem bark, branch and foliage biomass, respectively, whereas the total AGB equations explained on average 93% of the total observed variance in AGB. The inclusion of total height (h or diameter at breast height2 × total height (d2h as a predictor in the d-only based equations systems slightly improved estimates for stem wood, stem bark and total above-ground biomass, and greatly improved the estimates produced by the branch and foliage biomass equations. The predictive power of the proposed equations is higher than that of existing models for the study area. The fitted equations were used to estimate stand level AGB stocks from data on growing stock in 429 permanent sampling plots. Three machine-learning techniques were used to model the estimated stand level AGB and carbon contents; the selected models were used to map the AGB and carbon distributions in the study area, for which mean values of respectively 129.84 Mg ha−1 and 63.80 Mg ha−1 were obtained.

  18. Measurements of low energy neutral hydrogen efflux during ICRF heating

    International Nuclear Information System (INIS)

    Cohen, S.A.; Ruzic, D.; Voss, D.E.

    1984-09-01

    Using the Low Energy Neutral Atom Spectrometer, measurements were made of the H 0 and D 0 efflux from PLT during ion cyclotron heating experiments. The application of rf power at frequencies appropriate to fundamental and 2nd-harmonic heating results in a rapid, toroidally uniform rise in the charge-exchange efflux at a rate of about 10 15 cm -2 s -1 MW -1 . This flux increase is larger at lower plasma currents. The cause of this flux and its impact on plasma behavior are discussed

  19. MOLECULAR DYNAMICS COMPUTER SIMULATIONS OF MULTIDRUG RND EFFLUX PUMPS

    Directory of Open Access Journals (Sweden)

    Paolo Ruggerone

    2013-02-01

    Full Text Available Over-expression of multidrug efflux pumps of the Resistance Nodulation Division (RND protein super family counts among the main causes for microbial resistance against pharmaceuticals. Understanding the molecular basis of this process is one of the major challenges of modern biomedical research, involving a broad range of experimental and computational techniques. Here we review the current state of RND transporter investigation employing molecular dynamics simulations providing conformational samples of transporter components to obtain insights into the functional mechanism underlying efflux pump-mediated antibiotics resistance in Escherichia coli and Pseudomonas aeruginosa.

  20. Molecular Dynamics Computer Simulations of Multidrug RND Efflux Pumps

    Directory of Open Access Journals (Sweden)

    Paolo Ruggerone

    2013-02-01

    Full Text Available Over-expression of multidrug efflux pumps of the Resistance Nodulation Division (RND protein super family counts among the main causes for microbial resistance against pharmaceuticals. Understanding the molecular basis of this process is one of the major challenges of modern biomedical research, involving a broad range of experimental and computational techniques. Here we review the current state of RND transporter investigation employing molecular dynamics simulations providing conformational samples of transporter components to obtain insights into the functional mechanism underlying efflux pump-mediated antibiotics resistance in Escherichia coli and Pseudomonas aeruginosa.

  1. Ability of LANDSAT-8 Oli Derived Texture Metrics in Estimating Aboveground Carbon Stocks of Coppice Oak Forests

    Science.gov (United States)

    Safari, A.; Sohrabi, H.

    2016-06-01

    The role of forests as a reservoir for carbon has prompted the need for timely and reliable estimation of aboveground carbon stocks. Since measurement of aboveground carbon stocks of forests is a destructive, costly and time-consuming activity, aerial and satellite remote sensing techniques have gained many attentions in this field. Despite the fact that using aerial data for predicting aboveground carbon stocks has been proved as a highly accurate method, there are challenges related to high acquisition costs, small area coverage, and limited availability of these data. These challenges are more critical for non-commercial forests located in low-income countries. Landsat program provides repetitive acquisition of high-resolution multispectral data, which are freely available. The aim of this study was to assess the potential of multispectral Landsat 8 Operational Land Imager (OLI) derived texture metrics in quantifying aboveground carbon stocks of coppice Oak forests in Zagros Mountains, Iran. We used four different window sizes (3×3, 5×5, 7×7, and 9×9), and four different offsets ([0,1], [1,1], [1,0], and [1,-1]) to derive nine texture metrics (angular second moment, contrast, correlation, dissimilar, entropy, homogeneity, inverse difference, mean, and variance) from four bands (blue, green, red, and infrared). Totally, 124 sample plots in two different forests were measured and carbon was calculated using species-specific allometric models. Stepwise regression analysis was applied to estimate biomass from derived metrics. Results showed that, in general, larger size of window for deriving texture metrics resulted models with better fitting parameters. In addition, the correlation of the spectral bands for deriving texture metrics in regression models was ranked as b4>b3>b2>b5. The best offset was [1,-1]. Amongst the different metrics, mean and entropy were entered in most of the regression models. Overall, different models based on derived texture metrics

  2. Estimated carbon emission from recent rapid forest loss in Southeast Asia

    Science.gov (United States)

    Chen, A.; Zeng, Z.; Peng, L.; Fei, S.

    2017-12-01

    Driven by agricultural expansion, industrial logging, oil palm and rubber plantations, and urbanization, Southeast Asia (SEA) is one of the hotspots for tropical deforestation over recent decades. The extent of the tropical SEA deforestation rate, as well as its impacts on carbon cycle and biodiversity, however, is still highly uncertain. In relevant work using high resolution global maps of the 21st-century forest cover, we find tropical SEA lost 22 million hectares, or 9%, of forest area during 2000-2014, a much higher deforestation rate than previously reported. Here we further conduct research investigating carbon emissions from tropical deforestation in SEA with satellite data of forest cover, a global tropical forest biomass map, and Earth system models. Preliminary results suggest that deforestation in SEA causes about 2.8 Tg C emissions to the atmosphere during the same period, also higher than that of previous studies. Meanwhile, carbon emission from deforestation shows high variations across different countries, topography and between the insular and maritime SEA. Indonesia and Malaysia tops in both total carbon loss and loss from per unit land area. Our results indicates that previous studies have underestimated the carbon loss due to deforestation in SEA. And until further effective forest conservation measures can be adopted, tropical SEA will continue playing a role of atmospheric carbon source in the coming decades.

  3. Estimation of Net Ecosystem Carbon Exchange for the Conterminous UnitedStates by Combining MODIS and AmeriFlux Data

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Jingfeng; Zhuang, Qianlai; Baldocchi, Dennis D.; Law, Beverly E.; Richardson, Andrew D.; Chen, Jiquan; Oren, Ram; Starr, Gregory; Noormets, Asko; Ma, Siyan; Verma, Shashi B.; Wharton, Sonia; Wofsy, Steven C.; Bolstad, Paul V.; Burns, Sean P.; Cook, David R.; Curtis, Peter S.; Drake, Bert G.; Falk, Matthias; Fischer, Marc L.; Foster, David R.; Gu, Lianhong; Hadley, Julian L.; Hollinger, David Y.; Katul, Gabriel G.; Litvak, Marcy; Martin, Timothy A.; Matamala, Roser; McNulty, Steve; Meyers, Tilden P.; Monson, Russell K.; Munger, J. William; Oechel, Walter C.; U, Kyaw Tha Paw; Schmid, Hans Peter; Scott, Russell L.; Sun, Ge; Suyker, Andrew E.; Torn, Margaret S.

    2009-03-06

    Eddy covariance flux towers provide continuous measurements of net ecosystem carbon exchange (NEE) for a wide range of climate and biome types. However, these measurements only represent the carbon fluxes at the scale of the tower footprint. To quantify the net exchange of carbon dioxide between the terrestrial biosphere and the atmosphere for regions or continents, flux tower measurements need to be extrapolated to these large areas. Here we used remotely-sensed data from the Moderate Resolution Imaging Spectrometer (MODIS) instrument on board NASA's Terra satellite to scale up AmeriFlux NEE measurements to the continental scale. We first combined MODIS and AmeriFlux data for representative U.S. ecosystems to develop a predictive NEE model using a regression tree approach. The predictive model was trained and validated using NEE data over the periods 2000-2004 and 2005-2006, respectively. We found that the model predicted NEE reasonably well at the site level. We then applied the model to the continental scale and estimated NEE for each 1 km x 1 km cell across the conterminous U.S. for each 8-day period in 2005 using spatially-explicit MODIS data. The model generally captured the expected spatial and seasonal patterns of NEE. Our study demonstrated that our empirical approach is effective for scaling up eddy flux NEE measurements to the continental scale and producing wall-to-wall NEE estimates across multiple biomes. Our estimates may provide an independent dataset from simulations with biogeochemical models and inverse modeling approaches for examining the spatiotemporal patterns of NEE and constraining terrestrial carbon budgets for large areas.

  4. Estimation of net ecosystem carbon exchange for the conterminous United States by combining MODIS and AmeriFlux data

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Jingfeng; Zhuang, Qianlai; Baldocchi, Dennis D.; Bolstad, Paul V.; Burns, Sean P.; Chen, Jiquan; Cook, David R.; Curtis, Peter S.; Drake, Bert G.; Foster, David R.; Gu, Lianhong; Hadley, Julian L.; Hollinger, David Y.; Katul, Gabriel G.; Law, Beverly E.; Litvak, Marcy; Ma, Siyan; Martin, Timothy A.; Matamala, Roser; McNulty, Steve; Meyers, Tilden P.; Monson, Russell K.; Munger, J. William; Noormets, Asko; Oechel, Walter C.; Oren, Ram; Richardson, Andrew D.; Schmid, Hans Peter; Scott, Russell L.; Starr, Gregory; Sun, Ge; Suyker, Andrew E.; Torn, Margaret S.; Paw, Kyaw; Verma, Shashi B.; Wharton, Sonia; Wofsy, Steven C.

    2008-10-01

    Eddy covariance flux towers provide continuous measurements of net ecosystem carbon exchange (NEE) for a wide range of climate and biome types. However, these measurements only represent the carbon fluxes at the scale of the tower footprint. To quantify the net exchange of carbon dioxide between the terrestrial biosphere and the atmosphere for regions or continents, flux tower measurements need to be extrapolated to these large areas. Here we used remotely sensed data from the Moderate Resolution Imaging Spectrometer (MODIS) instrument on board the National Aeronautics and Space Administration's (NASA) Terra satellite to scale up AmeriFlux NEE measurements to the continental scale. We first combined MODIS and AmeriFlux data for representative U.S. ecosystems to develop a predictive NEE model using a modified regression tree approach. The predictive model was trained and validated using eddy flux NEE data over the periods 2000-2004 and 2005-2006, respectively. We found that the model predicted NEE well (r = 0.73, p < 0.001). We then applied the model to the continental scale and estimated NEE for each 1 km x 1 km cell across the conterminous U.S. for each 8-day interval in 2005 using spatially explicit MODIS data. The model generally captured the expected spatial and seasonal patterns of NEE as determined from measurements and the literature. Our study demonstrated that our empirical approach is effective for scaling up eddy flux NEE measurements to the continental scale and producing wall-to-wall NEE estimates across multiple biomes. Our estimates may provide an independent dataset from simulations with biogeochemical models and inverse modeling approaches for examining the spatiotemporal patterns of NEE and constraining terrestrial carbon budgets over large areas.

  5. Respiration of new and old carbon in the surface ocean: Implications for estimates of global oceanic gross primary productivity

    Science.gov (United States)

    Carvalho, Matheus C.; Schulz, Kai G.; Eyre, Bradley D.

    2017-06-01

    New respiration (Rnew, of freshly fixated carbon) and old respiration (Rold, of storage carbon) were estimated for different regions of the global surface ocean using published data on simultaneous measurements of the following: (1) primary productivity using 14C (14PP); (2) gross primary productivity (GPP) based on 18O or O2; and (3) net community productivity (NCP) using O2. The ratio Rnew/GPP in 24 h incubations was typically between 0.1 and 0.3 regardless of depth and geographical area, demonstrating that values were almost constant regardless of large variations in temperature (0 to 27°C), irradiance (surface to 100 m deep), nutrients (nutrient-rich and nutrient-poor waters), and community composition (diatoms, flagellates, etc,). As such, between 10 and 30% of primary production in the surface ocean is respired in less than 24 h, and most respiration (between 55 and 75%) was of older carbon. Rnew was most likely associated with autotrophs, with minor contribution from heterotrophic bacteria. Patterns were less clear for Rold. Short 14C incubations are less affected by respiratory losses. Global oceanic GPP is estimated to be between 70 and 145 Gt C yr-1.Plain Language SummaryHere we present a comprehensive coverage of ocean new and old respiration. Our results show that nearly 20% of oceanic gross primary production is consumed in the first 24 h. However, most (about 60%) respiration is of older carbon fixed at least 24 h before its consumption. Rates of new respiration relative to gross primary production were remarkably constant for the entire ocean, which allowed a preliminary estimation of global primary productivity as between 70 and 145 gt C yr-1.

  6. Estimating Carbon Stocks Along Depressional Wetlands Using Ground Penetrating Radar (GPR) in the Disney Wilderness Preserve (Orlando, Florida)

    Science.gov (United States)

    McClellan, M. D.; Comas, X.; Wright, W. J.; Mount, G. J.

    2014-12-01

    Peat soils store a large fraction of the global carbon (C) in soil. It is estimated that 95% of carbon in peatlands is stored in the peat soil, while less than 5% occurs in the vegetation. The majority of studies related to C stocks in peatlands have taken place in northern latitudes leaving the tropical and subtropical latitudes clearly understudied. In this study we use a combination of indirect non-invasive geophysical methods (mainly ground penetrating radar, GPR) as well as direct measurements (direct coring) to calculate total C stocks within subtropical depressional wetlands in the Disney Wilderness Preserve (DWP, Orlando, FL). A set of three-dimensional (3D) GPR surveys were used to detect variability of the peat layer thickness and the underlying peat-sand mix layer across several depressional wetlands. Direct samples collected at selected locations were used to confirm depth of each interface and to estimate C content in the laboratory. Layer thickness estimated from GPR and direct C content were used to estimate total peat volume and C content for the entire depressional wetland. Through the use of aerial photos a relationship between surface area along the depressional wetlands and total peat thickness (and thus C content) was established for the depressions surveyed and applied throughout the entire preserve. This work shows the importance of depressional wetlands as critical contributors of the C budget at the DWP.

  7. Carbon 14, carbon 13 and oxygen 18 in carbonate sediments from lake Titicaca. Preliminary estimates of sedimentation rate and paleoclimatological attempt

    International Nuclear Information System (INIS)

    Fontes, J.-C.; Boulange, Bruno; Rodrigo, L.-A.

    1981-01-01

    Stable isotope and radiocarbon measurements in carbonates from Titicaca lake indicate equilibrium with lake water and atmospheric CO 2 . Average sedimentation rate is close to 0,5 mm.yr -1 for the last millenium which was marked by large fluctuations of the hydrologic balance and lake level [fr

  8. Carbon 14, carbon 13 and oxygen 18 in carbonate sediments from Lake Titicaca. Preliminary estimates of sedimentation rate and paleoclimatological attempt

    Energy Technology Data Exchange (ETDEWEB)

    Fontes, J.C. (Paris-11 Univ., 91 - Orsay (France)); Boulange, B. (Orstom, 75 - Paris (France)); Rodrigo, L.A. (Universidad Mayor de San Andres, La Paz (Bolivia). Lab. de Fisica Cosmica de Chacaltaya)

    1981-07-06

    Stable isotope and radiocarbon measurements in carbonates from Lake Titicaca indicate equilibrium with lake water and atmospheric CO/sub 2/. Average sedimentation rate is close to 0,5 mm.yr/sup -1/ for the last millenium which was marked by large fluctuations of the hydrologic balance and lake level.

  9. Optimization Forest Thinning Measures for Carbon Budget in a Mixed Pine-Oak Stand of the Qingling Mountains, China: A Case Study

    Directory of Open Access Journals (Sweden)

    Lin Hou

    2016-11-01

    Full Text Available Forest thinning is a silviculture treatment for sustainable forest management. It may promote growth of the remaining individuals by decreasing stand density, reducing competition, and increasing light and nutrient availability to increase carbon sequestration in the forest ecosystem. However, the action also increases carbon loss simultaneously by reducing carbon and other nutrient inputs as well as exacerbating soil CO2 efflux. To achieve a maximum forest carbon budget, the central composite design with two independent variables (thinning intensity and thinning residual removal rate was explored in a natural pine-oak mixed stand in the Qinling Mountains, China. The net primary productivity of living trees was estimated and soil CO2 efflux was stimulated by the Yasso07 model. Based on two years observation, the preliminary results indicated the following. Evidently chemical compounds of the litter of the tree species affected soil CO2 efflux stimulation. The thinning residual removal rate had a larger effect than thinning intensity on the net ecosystem productivity. When the selective thinning intensity and residual removal rate was 12.59% and 66.62% concurrently, the net ecosystem productivity reached its maximum 53.93 t·ha−1·year−1. The lower thinning intensity and higher thinning residual removal rated benefited the net ecosystem productivity.

  10. Carbon Accounting and Cost Estimation in Forestry Projects Using CO2Fix V.3

    International Nuclear Information System (INIS)

    Groen, T.; Nabuurs, G.J.; Schelhaas, M.J.

    2006-01-01

    Carbon and financial accounting of projects in the Land Use, Land-Use Change and Forestry sector is a topic of hot debate. Large uncertainty remains concerning the carbon dynamics, the way they should be accounted and the cost efficiency of the projects. Part of the uncertainty can be alleviated by standardisation and transparency of reporting methods. For this reason we further developed CO2FIX, a forest ecosystem carbon model, with modules for carbon and financial accounting. The model is applied to four cases: (1) Joint implementation afforestation project in Romania, (2) Forest management project in Central Europe, (3) Reduced impact logging possibly under the Clean Development Mechanism (CDM) in the future, and (4) Afforestation with native species under the Clean Development Mechanism. The results show the wide applicability of CO2FIX, from degrading grasslands as baseline cases to multiple cohort forest ecosystems. Also the results show that Forest Management in the European case can generate considerable amounts of carbon emission reductions. Further, the results show that although reduced impact logging is not yet an allowed option under the Clean Development Mechanism, it shows promising results in that it is (1) very cost effective, (2) seems to be able to generate intermediate amounts of credits and (3) seems to us as a project type that is not prone to leakage issues. These results are yet another indication to seriously consider reduced impact logging as an eligible measure under the CDM

  11. New methodology for estimating biofuel consumption for cooking: Atmospheric emissions of black carbon and sulfur dioxide from India

    Science.gov (United States)

    Habib, Gazala; Venkataraman, Chandra; Shrivastava, Manish; Banerjee, Rangan; Stehr, J. W.; Dickerson, Russell R.

    2004-09-01

    The dominance of biofuel combustion emissions in the Indian region, and the inherently large uncertainty in biofuel use estimates based on cooking energy surveys, prompted the current work, which develops a new methodology for estimating biofuel consumption for cooking. This is based on food consumption statistics, and the specific energy for food cooking. Estimated biofuel consumption in India was 379 (247-584) Tg yr-1. New information on the user population of different biofuels was compiled at a state level, to derive the biofuel mix, which varied regionally and was 74:16:10%, respectively, of fuelwood, dung cake and crop waste, at a national level. Importantly, the uncertainty in biofuel use from quantitative error assessment using the new methodology is around 50%, giving a narrower bound than in previous works. From this new activity data and currently used black carbon emission factors, the black carbon (BC) emissions from biofuel combustion were estimated as 220 (65-760) Gg yr-1. The largest BC emissions were from fuelwood (75%), with lower contributions from dung cake (16%) and crop waste (9%). The uncertainty of 245% in the BC emissions estimate is now governed by the large spread in BC emission factors from biofuel combustion (122%), implying the need for reducing this uncertainty through measurements. Emission factors of SO2 from combustion of biofuels widely used in India were measured, and ranged 0.03-0.08 g kg-1 from combustion of two wood species, 0.05-0.20 g kg-1 from 10 crop waste types, and 0.88 g kg-1 from dung cake, significantly lower than currently used emission factors for wood and crop waste. Estimated SO2 emissions from biofuels of 75 (36-160) Gg yr-1 were about a factor of 3 lower than that in recent studies, with a large contribution from dung cake (73%), followed by fuelwood (21%) and crop waste (6%).

  12. Efflux pumps of Mycobacterium tuberculosis play a significant role in antituberculosis activity of potential drug candidates.

    Science.gov (United States)

    Balganesh, Meenakshi; Dinesh, Neela; Sharma, Sreevalli; Kuruppath, Sanjana; Nair, Anju V; Sharma, Umender

    2012-05-01

    Active efflux of drugs mediated by efflux pumps that confer drug resistance is one of the mechanisms developed by bacteria to counter the adverse effects of antibiotics and chemicals. To understand these efflux mechanisms in Mycobacterium tuberculosis, we generated knockout (KO) mutants of four efflux pumps of the pathogen belonging to different classes. We measured the MICs and kill values of two different compound classes on the wild type (WT) and the efflux pump (EP) KO mutants in the presence and absence of the efflux inhibitors verapamil and l-phenylalanyl-l-arginyl-β-naphthylamide (PAβN). Among the pumps studied, the efflux pumps belonging to the ABC (ATP-binding cassette) class, encoded by Rv1218c, and the SMR (small multidrug resistance) class, encoded by Rv3065, appear to play important roles in mediating the efflux of different chemical classes and antibiotics. Efflux pumps encoded by Rv0849 and Rv1258c also mediate the efflux of these compounds, but to a lesser extent. Increased killing is observed in WT M. tuberculosis cells by these compounds in the presence of either verapamil or PAβN. The efflux pump KO mutants were more susceptible to these compounds in the presence of efflux inhibitors. We have shown that these four efflux pumps of M. tuberculosis play a vital role in mediating efflux of different chemical scaffolds. Inhibitors of one or several of these efflux pumps could have a significant impact in the treatment of tuberculosis. The identification and characterization of Rv0849, a new efflux pump belonging to the MFS (major facilitator superfamily) class, are reported.

  13. CO2 efflux from subterranean nests of ant communities in a seasonal tropical forest, Thailand

    OpenAIRE

    Hasin, Sasitorn; Ohashi, Mizue; Yamada, Akinori; Hashimoto, Yoshiaki; Tasen, Wattanachai; Kume, Tomonori; Yamane, Seiki

    2014-01-01

    Many ant species construct subterranean nests. The presence of their nests may explain soil respiration “hot spots”, an important factor in the high CO2 efflux from tropical forests. However, no studies have directly measured CO2 efflux from ant nests. We established 61 experimental plots containing 13 subterranean ant species to evaluate the CO2 efflux from subterranean ant nests in a tropical seasonal forest, Thailand. We examined differences in nest CO2 efflux among ant species. We determi...

  14. A mechanistic modelling and data assimilation approach to estimate the carbon/chlorophyll and carbon/nitrogen ratios in a coupled hydrodynamical-biological model

    Directory of Open Access Journals (Sweden)

    B. Faugeras

    2004-01-01

    Full Text Available The principal objective of hydrodynamical-biological models is to provide estimates of the main carbon fluxes such as total and export oceanic production. These models are nitrogen based, that is to say that the variables are expressed in terms of their nitrogen content. Moreover models are calibrated using chlorophyll data sets. Therefore carbon to chlorophyll (C:Chl and carbon to nitrogen (C:N ratios have to be assumed. This paper addresses the problem of the representation of these ratios. In a 1D framework at the DYFAMED station (NW Mediterranean Sea we propose a model which enables the estimation of the basic biogeochemical fluxes and in which the spatio-temporal variability of the C:Chl and C:N ratios is fully represented in a mechanical way. This is achieved through the introduction of new state variables coming from the embedding of a phytoplankton growth model in a more classical Redfieldian NNPZD-DOM model (in which the C:N ratio is assumed to be a constant. Following this modelling step, the parameters of the model are estimated using the adjoint data assimilation method which enables the assimilation of chlorophyll and nitrate data sets collected at DYFAMED in 1997.Comparing the predictions of the new Mechanistic model with those of the classical Redfieldian NNPZD-DOM model which was calibrated with the same data sets, we find that both models reproduce the reference data in a comparable manner. Both fluxes and stocks can be equally well predicted by either model. However if the models are coinciding on an average basis, they are diverging from a variability prediction point of view. In the Mechanistic model biology adapts much faster to its environment giving rise to higher short term variations. Moreover the seasonal variability in total production differs from the Redfieldian NNPZD-DOM model to the Mechanistic model. In summer the Mechanistic model predicts higher production values in carbon unit than the Redfieldian NNPZD

  15. A direct estimate of evapotranspiration over the Amazon basin and implications for our understanding of carbon and water cycling

    Science.gov (United States)

    Swann, A. L. S.; Koven, C.; Lombardozzi, D.; Bonan, G. B.

    2017-12-01

    Evapotranspiration (ET) is a critical term in the surface energy budget as well as the water cycle. There are few direct measurements of ET, and thus the magnitude and variability is poorly constrained at large spatial scales. Estimates of the annual cycle of ET over the Amazon are critical because they influence predictions of the seasonal cycle of carbon fluxes, as well as atmospheric dynamics and circulation. We estimate ET for the Amazon basin using a water budget approach, by differencing rainfall, discharge, and time-varying storage from the Gravity Recovery and Climate Experiment. We find that the climatological annual cycle of ET over the Amazon basin upstream of Óbidos shows suppression of ET during the wet season, and higher ET during the dry season, consistent with flux tower based observations in seasonally dry forests. We also find a statistically significant decrease in ET over the time period 2002-2015 of -1.46 mm/yr. Our direct estimate of the seasonal cycle of ET is largely consistent with previous indirect estimates, including energy budget based approaches, an up-scaled station based estimate, and land surface model estimates, but suggests that suppression of ET during the wet season is underestimated by existing products. We further quantify possible contributors to the phasing of the seasonal cycle and downward time trend using land surface models.

  16. Estimation of the carbon footprint of the Galician fishing activity (NW Spain)

    International Nuclear Information System (INIS)

    Iribarren, Diego; Vazquez-Rowe, Ian; Hospido, Almudena; Moreira, Maria Teresa; Feijoo, Gumersindo

    2010-01-01

    The food production system as a whole is recognized as one of the major contributors to environmental impacts. Accordingly, food production, processing, transport and consumption account for a relevant portion of the greenhouse gas (GHG) emissions associated with any country. In this context, there is an increasing market demand for climate-relevant information regarding the global warming impact of consumer food products throughout the supply chains. This article deals with the assessment of the carbon footprint of seafood products as a key subgroup in the food sector. Galicia (NW Spain) was selected as a case study. The analysis is based on a representative set of species within the Galician fishing sector, including species obtained from coastal fishing (e.g. horse mackerel, Atlantic mackerel, European pilchard and blue whiting), offshore fishing (e.g. European hake, megrim and anglerfish), deep-sea fishing (skipjack and yellowfin tuna), extensive aquaculture (mussels) and intensive aquaculture (turbot). The carbon footprints associated with the production-related activities of each selected species were quantified following a business-to-business approach on the basis of 1 year of fishing activity. These individual carbon footprints were used to calculate the carbon footprint for each of the different Galician fisheries and culture activities. Finally, the lump sum of the carbon footprints for coastal, offshore and deep-sea fishing and extensive and intensive aquaculture brought about the carbon footprint of the Galician fishing activity (i.e., capture and culture). A benchmark for quantifying and communicating emission reductions was then provided, and opportunities to reduce the GHG emissions associated with the Galician fishing activity could be prioritized.

  17. Carbon Footprint Estimation in Fiber Optics Industry: A Case Study of OFS Fitel, LLC

    Directory of Open Access Journals (Sweden)

    Suresh Inakollu

    2017-05-01

    Full Text Available Detailed carbon footprinting assignments have been on the rise in more and more major manufacturing industries. The main strength of carbon footprinting is to make product manufacturers aware of carbon emissions and understand its meaning due to perceived global warming effects. Carbon foot-printing through life-cycle assessment in conjunction with greenhouse gas (GHG accounting is essential for identifying opportunities for environmental efficiencies. Case studies of goods that require more complex production elements have also been increasing, like optical fiber manufacturing. From making ultra-pure glass rods to elongating hot fibers, the whole process involves using a high volume of chemicals and extensive energy. Hence, standard numbers addressing carbon footprinting specifically for fiber optics is helpful for the quantification of greenhouse gas intensity, mitigation of global warming, and adaptation against future climate change scenarios. This paper calculates and helps standardize the emission factor for the production of optical fiber from the scope of gate-to-gate: 4.81 tonnes CO2eq per million meters of produced fiber (which is 72.92 kg CO2eq per kg of produced fiber in order to allow other industries to use this information in their own carbon footprint calculations. Since governmental regulatory agencies have largely failed to confront the risks associated with climate change borne by industries, it is essential for all industries to disclose their emissions in a standardized and comparable form in order to develop standard guidelines for all. This paper provides a practical life-cycle approach, concludes with requirements for further research and evaluation.

  18. Estimation of the carbon footprint of the Galician fishing activity (NW Spain).

    Science.gov (United States)

    Iribarren, Diego; Vázquez-Rowe, Ian; Hospido, Almudena; Moreira, María Teresa; Feijoo, Gumersindo

    2010-10-15

    The food production system as a whole is recognized as one of the major contributors to environmental impacts. Accordingly, food production, processing, transport and consumption account for a relevant portion of the greenhouse gas (GHG) emissions associated with any country. In this context, there is an increasing market demand for climate-relevant information regarding the global warming impact of consumer food products throughout the supply chains. This article deals with the assessment of the carbon footprint of seafood products as a key subgroup in the food sector. Galicia (NW Spain) was selected as a case study. The analysis is based on a representative set of species within the Galician fishing sector, including species obtained from coastal fishing (e.g. horse mackerel, Atlantic mackerel, European pilchard and blue whiting), offshore fishing (e.g. European hake, megrim and anglerfish), deep-sea fishing (skipjack and yellowfin tuna), extensive aquaculture (mussels) and intensive aquaculture (turbot). The carbon footprints associated with the production-related activities of each selected species were quantified following a business-to-business approach on the basis of 1year of fishing activity. These individual carbon footprints were used to calculate the carbon footprint for each of the different Galician fisheries and culture activities. Finally, the lump sum of the carbon footprints for coastal, offshore and deep-sea fishing and extensive and intensive aquaculture brought about the carbon footprint of the Galician fishing activity (i.e., capture and culture). A benchmark for quantifying and communicating emission reductions was then provided, and opportunities to reduce the GHG emissions associated with the Galician fishing activity could be prioritized. Copyright © 2010 Elsevier B.V. All rights reserved.

  19. Application of probabilistic facies prediction and estimation of rock physics parameters in a carbonate reservoir from Iran

    International Nuclear Information System (INIS)

    Karimpouli, Sadegh; Hassani, Hossein; Nabi-Bidhendi, Majid; Khoshdel, Hossein; Malehmir, Alireza

    2013-01-01

    In this study, a carbonate field from Iran was studied. Estimation of rock properties such as porosity and permeability is much more challenging in carbonate rocks than sandstone rocks because of their strong heterogeneity. The frame flexibility factor (γ) is a rock physics parameter which is related not only to pore structure variation but also to solid/pore connectivity and rock texture in carbonate reservoirs. We used porosity, frame flexibility factor and bulk modulus of fluid as the proper parameters to study this gas carbonate reservoir. According to rock physics parameters, three facies were defined: favourable and unfavourable facies and then a transition facies located between these two end members. To capture both the inversion solution and associated uncertainty, a complete implementation of the Bayesian inversion of the facies from pre-stack seismic data was applied to well data and validated with data from another well. Finally, this method was applied on a 2D seismic section and, in addition to inversion of petrophysical parameters, the high probability distribution of favorable facies was also obtained. (paper)

  20. Black carbon concentration and deposition estimations in Finland by the regional aerosol–climate model REMO-HAM

    Directory of Open Access Journals (Sweden)

    A. I. Hienola

    2013-04-01

    Full Text Available The prediction skill of the regional aerosol–climate model REMO-HAM was assessed against the black carbon (BC concentration measurements from five locations in Finland, with focus on Hyytiälä station for the year 2005. We examined to what extent the model is able to reproduce the measurements using several statistical tools: median comparison, overlap coefficient (OVL; the common area under two probability distributions curves and Z score (a measure of standard deviation, shape and spread of the distributions. The results of the statistics showed that the model is biased low. The local and regional emissions of BC have a significant contribution, and the model tendency to flatten the observed BC is most likely dominated by the lack of domestic burning of biofuel in the emission inventories. A further examination of the precipitation data from both measurements and model showed that there is no correlation between REMO's excessive precipitation and BC underestimation. This suggests that the excessive wet removal is not the main cause of the low black carbon concentration output. In addition, a comparison of wind directions in relation with high black carbon concentrations shows that REMO-HAM is able to predict the BC source directions relatively well. Cumulative black carbon deposition fluxes over Finland were estimated, including the deposition on snow.

  1. In-silico identification and phylogenetic analysis of auxin efflux ...

    African Journals Online (AJOL)

    ufuoma

    2014-01-08

    Jan 8, 2014 ... PIN proteins of Arabidopsis viz., PIN1,PIN4 and PIN7 show plasma membrane .... The central hydrophilic loop is dynamic in nature and differs from each other in terms ... research of this plant at the molecular level. Auxin efflux.

  2. Effect of phosphorus limiting on phytase activity, proton efflux and ...

    African Journals Online (AJOL)

    This work intended to measure the nodulated-roots oxygen consumption, proton efflux and phytase activity in 2 lines of common bean (Phaseolus vulgaris) (115, 147) at 2 levels of P supply. Rooted seedlings were inoculated with Rhizobium tropici CIAT 899 in hydroaeroponic cultivation under glasshouse. Phosphorus was ...

  3. Efflux drug transporters at the forefront of antimicrobial resistance.

    Science.gov (United States)

    Rahman, Tahmina; Yarnall, Benjamin; Doyle, Declan A

    2017-10-01

    Bacterial antibiotic resistance is rapidly becoming a major world health consideration. To combat antibiotics, microorganisms employ their pre-existing defence mechanisms that existed long before man's discovery of antibiotics. Bacteria utilise levels of protection that range from gene upregulation, mutations, adaptive resistance, and production of resistant phenotypes (persisters) to communal behaviour, as in swarming and the ultimate defence of a biofilm. A major part of all of these responses involves the use of antibiotic efflux transporters. At the single cell level, it is becoming apparent that the use of efflux pumps is the first line of defence against an antibiotic, as these pumps decrease the intracellular level of antibiotic while the cell activates the various other levels of protection. This frontline of defence involves a coordinated network of efflux transporters. In the future, inhibition of this efflux transporter network, as a target for novel antibiotic therapy, will require the isolation and then biochemical/biophysical characterisation of each pump against all known and new antibiotics. This depth of knowledge is required so that we can fully understand and tackle the mechanisms of developing antimicrobial resistance.

  4. IP3 stimulates CA++ efflux from fusogenic carrot protoplasts

    International Nuclear Information System (INIS)

    Rincon, M.; Boss, W.F.

    1986-01-01

    Polyphosphoinositide breakdown plays an important role in signal transduction in animal cells (Berridge and Irvine, 1984, Nature, 312:315). Upon stimulation, phospholipase C hydrolyzes phosphatidylinositol 4,5-bisphosphate to inositol 1,4,5-trisphosphate (IP 3 ) and diacylglycerol both of which act as cellular second messengers. IP 3 mobilizes Ca ++ from internal stores, hence the cytosolic free Ca ++ concentration increases and those physiological activities regulated by Ca ++ are stimulated. To test if plant cells also responded to IP 3 , Ca ++ efflux studies were done with fusogenic carrot protoplasts released in EGTA. The protoplasts were preloaded with 45 Ca ++ placed in a Ca ++ -free medium, and efflux determined as 45 Ca ++ loss from the protoplasts. IP 3 (10-20μM) caused enhanced 45 Ca ++ efflux and the response was sustained for at least 15 min. In plants, as in animals, the observed IP 3 -enhanced 45 Ca ++ efflux suggested that IP 3 released Ca ++ from internal stores, and the increased free cytosolic Ca ++ activated Ca ++ pumping mechanisms which restored the Ca ++ concentration in the cytosol to the normal level

  5. Moderate alcohol consumption increases cholesterol efflux mediated by ABCA1

    NARCIS (Netherlands)

    Beulens, J.W.J.; Sierksma, A.; Tol, A. van; Fournier, N.; Gent, T. van; Paul, J.L.; Hendriks, H.F.J.

    2004-01-01

    Moderate alcohol consumption increases HDL cholesterol, which is involved in reverse cholesterol transport (RCT). The aim of this study was to investigate the effect of moderate alcohol consumption on cholesterol efflux, using J774 mouse macrophages and Fu5AH cells, and on other parameters in the

  6. Estimation of surface area and pore volume of activated carbons by methylene blue and iodine numbers

    Directory of Open Access Journals (Sweden)

    Cleiton A. Nunes

    2011-01-01

    Full Text Available Data of methylene blue number and iodine number of activated carbons samples were calibrated against the respective surface area, micropore volume and total pore volume using multiple regression. The models obtained from the calibrations were used in predicting these physical properties of a test group of activated carbon samples produced from several raw materials. In all cases, the predicted values were in good agreement with the expected values. The method allows extracting more information from the methylene blue and iodine adsorption studies than normally obtained with this type of material.

  7. Primary estimation of forming date for carbonate weathering crust in Guizhou province

    International Nuclear Information System (INIS)

    Liu Chunru; Liu Xiuming; Wang Shijie; Wan Jinglin; Zheng Dewen

    2008-01-01

    The problem of directed dating of carbonate weathering crust in Guizhou Province hasn't been resolved. On the base of our previous study, we tested in detail the ages of antigenic quartz grains by fission track dating method and give a limitation of the forming date to carbonate weathering crust. The results show that the age of Xinpu profile is younger than 8.5 Ma, and the age of Guanba profile is younger than 7.3 Ma, and the age of Daxing profile is younger than 4.6 Ma. (authors)

  8. CO2 efflux from subterranean nests of ant communities in a seasonal tropical forest, Thailand.

    Science.gov (United States)

    Hasin, Sasitorn; Ohashi, Mizue; Yamada, Akinori; Hashimoto, Yoshiaki; Tasen, Wattanachai; Kume, Tomonori; Yamane, Seiki

    2014-10-01

    Many ant species construct subterranean nests. The presence of their nests may explain soil respiration "hot spots", an important factor in the high CO2 efflux from tropical forests. However, no studies have directly measured CO2 efflux from ant nests. We established 61 experimental plots containing 13 subterranean ant species to evaluate the CO2 efflux from subterranean ant nests in a tropical seasonal forest, Thailand. We examined differences in nest CO2 efflux among ant species. We determined the effects of environmental factors on nest CO2 efflux and calculated an index of nest structure. The mean CO2 efflux from nests was significantly higher than those from the surrounding soil in the wet and dry seasons. The CO2 efflux was species-specific, showing significant differences among the 13 ant species. The soil moisture content significantly affected nest CO2 efflux, but there was no clear relationship between nest CO2 efflux and nest soil temperature. The diameter of the nest entrance hole affected CO2 efflux. However, there was no significant difference in CO2 efflux rates between single-hole and multiple-hole nests. Our results suggest that in a tropical forest ecosystem the increase in CO2 efflux from subterranean ant nests is caused by species-specific activity of ants, the nest soil environment, and nest structure.

  9. Regional myocardial oxygen consumption estimated by carbon-11 acetate and positron emission tomography before and after repetitive ischemia

    DEFF Research Database (Denmark)

    Kofoed, K F; Hansen, P R; Holm, S

    2000-01-01

    alternating with 5 minutes of reperfusion. Before and after repetitive coronary occlusions, oxygen 15 water/oxygen 15 carbon monoxide (blood flow), and 11C-acetate (oxygen consumption) PET imaging were performed. Left ventricular regional systolic wall thickening was measured with sonomicrometry. Forty......BACKGROUND: Preserved myocardial oxygen consumption estimated by carbon 11-acetate and positron emission tomography (PET) in myocardial regions with chronic but reversibly depressed contractile function in patients with ischemic heart disease have been suggested to be caused by repeated short......-five minutes after the ischemic episodes, systolic ventricular wall thickening was decreased by 90%, whereas myocardial blood flow was reduced by 21% compared with baseline values (P consumption was unaltered compared with the baseline level...

  10. Carbon-13 nuclear magnetic resonance of strained organic molecules: III estimates of steric effects

    International Nuclear Information System (INIS)

    Seidl, P.R.; Leal, K.Z.; Costa, V.E.U.; Rio Grande do Sul Univ., Porto Alegre

    1985-01-01

    A study of cyclic organic molecules using carbon-13 NMR spectroscopy is analysed. The preparation of compounds and the use of norbornyl compounds as a basis for chemical shifts, bicyclic, tricyclic and tetracyclic derivatives are compared. Relevant distances, angles and non-bonded interactions are shown. (M.J.C.) [pt

  11. Assessing the uncertainty of forest carbon estimates using the FVS family of diameter increment equations

    Science.gov (United States)

    Matthew B. Russell; Aaron R. Weiskittel; Anthony W. D’Amato

    2012-01-01

    Serving as a carbon (C) accounting tool, the Forest Vegetation Simulator (FVS) is widely used by forest managers and researchers to forecast future forest C stocks. Assessments of the uncertainty that FVS equations provide in terms of their ability to accurately project forest biomass and C would seemingly differ, depending on the region and scale of interest to the...

  12. A Spatio-Temporal Based Estimation of Sequestered Carbon in the ...

    African Journals Online (AJOL)

    The vegetation in the Tarkwa Mining Area (TMA) has experienced changes as a result of population growth, urbanization, mining activities and illegal chainsaw operations and this has led to an increase in temperature over the past years. Therefore, studying its forest biomass carbon (C) stock and its spatio-temporal ...

  13. Preliminary estimation of bryophyte biomass and carbon pool from three contrasting different vegetation types

    Czech Academy of Sciences Publication Activity Database

    Singh, M.K.; Juhász, A.; Csintalan, Z.; Kaligaric, M.; Marek, Michal V.; Urban, Otmar; Tuba, Z.

    2005-01-01

    Roč. 33, č. 1 (2005), s. 267-270 ISSN 0133-3720 Grant - others:EU(CZ) HPRI-CT-2002-00197 Institutional research plan: CEZ:AV0Z60870520 Keywords : bryophyte * carbon pool * rain forest Subject RIV: EH - Ecology, Behaviour Impact factor: 0.320, year: 2005

  14. Estimating marine biogeochemical rates of the carbonate pH system—A Kalman filter tested

    NARCIS (Netherlands)

    Soetaert, K.E.R.; Grégoire, M.

    2011-01-01

    Oxygen (O2), nitrate (NO3), dissolved inorganic carbon (DIC) or pCO2, and pH or total alkalinity (TA), are useful indices of marine chemical, physical and biological processes operating on varying time-scales. Although these properties are increasingly being monitored at high frequency, they have

  15. Fractionation of whey protein isolate with supercritical carbon dioxide – process modeling and cost estimation

    Science.gov (United States)

    An economical and environmentally friendly whey protein fractionation process was developed using supercritical carbon dioxide (sCO2) as an acid to produce enriched fractions of alpha-lactalbumin (alpha-La) and beta-lactoglobulin (beta-Lg) from a commercial whey protein isolate (WPI) containing 55% ...

  16. Identifying potential sources of variability between vegetation carbon storage estimates for urban areas

    DEFF Research Database (Denmark)

    Davies, Zoe G.; Dallimer, Martin; Edmondson, Jill L.

    2013-01-01

    Although urbanisation is a major cause of land-use change worldwide, towns and cities remain relatively understudied ecosystems. Research into urban ecosystem service provision is still an emerging field, yet evidence is accumulating rapidly to suggest that the biological carbon stores in cities ...

  17. Carbon Sequestration in loblolly pine plantations: Methods, limitations, and research needs for estimating storage pools

    Science.gov (United States)

    Kurt Johnsen; Bob Teskey; Lisa Samuelson; John Butnor; David Sampson; Felipe Sanchez; Chris Maier; Steve McKeand

    2004-01-01

    Globally, the species most widely used for plantation forestry is loblolly pine (Pinus taeda L.). Because loblolly pine plantations are so extensive and grow so rapidly, they provide a great potential for sequestering atmospheric carbon (C). Because loblolly pine plantations are relatively simple ecosystems and because such a great volume of...

  18. Robust Means for Estimating Black Carbon-Water Sorption Coefficients of Organic Contaminants in Sediments

    Science.gov (United States)

    2015-07-01

    compounds by black carbon, Springer, Dordrecht. Plata, D.L., Hemingway , J.D. and Gschwend, P.M. (2015) Polyparameter linear free energy relationship for...1320-1331. 32 8. Appendices Scientific/Technical Publications Plata, D.L., J.D. Hemingway , and P.M. Gschwend. Polyparameter linear free energy

  19. Estimating long-term carbon sequestration patterns in even- and uneven-aged southern pine stands

    Science.gov (United States)

    Don C. Bragg; James M. Guldin

    2010-01-01

    Carbon (C) sequestration has become an increasingly important consideration for forest management in North America, and has particular potential in pine-dominated forests of the southern United States. Using existing literature on plantations and long-term studies of naturally regenerated loblolly (Pinus taeda) and shortleaf (Pinus echinata) pine-dominated stands on...

  20. Using carbon emissions and oxygen consumption to estimate energetics parameters of cattle consuming forages

    Science.gov (United States)

    To evaluate newer indirect calorimetry system to quantify energetic parameters, 8 cross-bred beef steers (initial BW = 241 ± 4.10 kg) were used in a 77-d experiment to examine energetics parameters calculated from carbon dioxide (CO2), methane (CH4), and oxygen (O2) fluxes. Steers were individually ...

  1. Computer simulation and interpretation of 45Ca efflux profile patterns

    International Nuclear Information System (INIS)

    Borle, A.B.; Uchikawa, T.; Anderson, J.H.

    1982-01-01

    Stimulations or inhibitions by various agents of 45 Ca efflux from prelabeled cells or tissues display distinct and reproducible profile patterns when the results are plotted against time as fractional efflux ratios (FER). FER is the fractional efflux of 45 Ca from stimulated cells divided by the fractional efflux from a control unstimulated group. These profile patterns fall into three categories: peak patterns, exponential patterns, and mixed patterns. Each category can be positive (stimulation) or negative (inhibition). The interpretation of these profiles is difficult because 45 Ca efflux depends on three variables: the rate of calcium transport out of the cell, the specific activity of the cell compartment from which the calcium originates, and the concentration of free calcium in this compartment. A computer model based on data obtained by kinetic analyses of 45 Ca desaturation curves and consisting of two distinct intracellular pools was designed to follow the concentration of the traced substance ( 40 Ca), the tracer ( 45 Ca), and the specific activity of each compartment before, during, and after the stimulation or the inhibition of calcium fluxes at various pool boundaries. The computer model can reproduce all the FER profiles obtained experimentally and bring information which may be helpful to the interpretation of this type of data. Some predictions of the model were tested experimentally, and the results support the views that a peak pattern may reflect a sustained change in calcium transport across the plasma membrane, that an exponential pattern arises from calcium mobilization from an internal subcellular pool, and that a mixed pattern may be caused by a simultaneous change in calcium fluxes at both compartment boundaries

  2. Calcium efflux systems in stress signalling and adaptation in plants

    Directory of Open Access Journals (Sweden)

    Jayakumar eBose

    2011-12-01

    Full Text Available Transient cytosolic calcium ([Ca2+]cyt elevation is an ubiquitous denominator of the signalling network when plants are exposed to literally every known abiotic and biotic stress. These stress-induced [Ca2+]cyt elevations vary in magnitude, frequency and shape, depending on the severity of the stress as well the type of stress experienced. This creates a unique stress-specific calcium signature that is then decoded by signal transduction networks. While most published papers have been focused predominantly on the role of Ca2+ influx mechanisms in shaping [Ca2+]cyt signatures, restoration of the basal [Ca2+]cyt levels is impossible without both cytosolic Ca2+ buffering and efficient Ca2+ efflux mechanisms removing excess Ca2+ from cytosol, to reload Ca2+ stores and to terminate Ca2+ signalling. This is the topic of the current review. The molecular identity of two major types of Ca2+ efflux systems, Ca2+-ATPase pumps and Ca2+/H+ exchangers, is described, and their regulatory modes are analysed in detail. The spatial and temporal organisation of calcium signalling networks is described, and the importance of existence of intracellular calcium microdomains is discussed. Experimental evidence for the role of Ca2+ efflux systems in plant responses to a range of abiotic and biotic factors is summarised. Contribution of Ca2+-ATPase pumps and Ca2+/H+ exchangers in shaping [Ca2+]cyt signatures is then modelled by using a four-component model (plasma- and endo- membrane-based Ca2+-permeable channels and efflux systems taking into account the cytosolic Ca2+ buffering. It is concluded that physiologically relevant variations in the activity of Ca2+-ATPase pumps and Ca2+/H+ exchangers are sufficient to fully describe all the reported experimental evidence and determine the shape of [Ca2+]cyt signatures in response to environmental stimuli, emphasising the crucial role these active efflux systems play in plant adaptive responses to environment.

  3. Deciphering the role of RND efflux transporters in Burkholderia cenocepacia.

    Directory of Open Access Journals (Sweden)

    Silvia Bazzini

    Full Text Available Burkholderia cenocepacia J2315 is representative of a highly problematic group of cystic fibrosis (CF pathogens. Eradication of B. cenocepacia is very difficult with the antimicrobial therapy being ineffective due to its high resistance to clinically relevant antimicrobial agents and disinfectants. RND (Resistance-Nodulation-Cell Division efflux pumps are known to be among the mediators of multidrug resistance in gram-negative bacteria. Since the significance of the 16 RND efflux systems present in B. cenocepacia (named RND-1 to -16 has been only partially determined, the aim of this work was to analyze mutants of B. cenocepacia strain J2315 impaired in RND-4 and RND-9 efflux systems, and assess their role in the efflux of toxic compounds. The transcriptomes of mutants deleted individually in RND-4 and RND-9 (named D4 and D9, and a double-mutant in both efflux pumps (named D4-D9, were compared to that of the wild-type B. cenocepacia using microarray analysis. Microarray data were confirmed by qRT-PCR, phenotypic experiments, and by Phenotype MicroArray analysis. The data revealed that RND-4 made a significant contribution to the antibiotic resistance of B. cenocepacia, whereas RND-9 was only marginally involved in this process. Moreover, the double mutant D4-D9 showed a phenotype and an expression profile similar to D4. The microarray data showed that motility and chemotaxis-related genes appeared to be up-regulated in both D4 and D4-D9 strains. In contrast, these gene sets were down-regulated or expressed at levels similar to J2315 in the D9 mutant. Biofilm production was enhanced in all mutants. Overall, these results indicate that in B. cenocepacia RND pumps play a wider role than just in drug resistance, influencing additional phenotypic traits important for pathogenesis.

  4. Dissolved inorganic carbon and alkalinity fluxes from coastal marine sediments: Model estimates for different shelf environments and sensitivity to global change

    NARCIS (Netherlands)

    Krumins, V.; Gehlen, M.; Arndt, S.; Van Cappellen, P.; Regnier, P.

    2013-01-01

    We present a one-dimensional reactive transport model to estimate benthic fluxes of dissolved inorganic carbon (DIC) and alkalinity (AT) from coastal marine sediments. The model incorporates the transport processes of sediment accumulation, molecular diffusion, bioturbation and bioirrigation,

  5. Estimates of greenhouse gas and black carbon emissions from a major Australian wildfire with high spatiotemporal resolution

    Science.gov (United States)

    Surawski, N. C.; Sullivan, A. L.; Roxburgh, S. H.; Polglase, P. J.

    2016-08-01

    Estimates of greenhouse gases and particulate emissions are made with a high spatiotemporal resolution from the Kilmore East fire in Victoria, Australia, which burnt approximately 100,000 ha over a 12 h period. Altogether, 10,175 Gigagrams (Gg) of CO2 equivalent (CO2-e) emissions occurred, with CO2 (˜68%) being the dominant chemical species emitted followed by CH4 (˜17%) and black carbon (BC) (˜15%). About 63% of total CO2-e emissions were estimated to be from coarse woody debris, 22% were from surface fuels, 7% from bark, 6% from elevated fuels, and less than 2% from tree crown consumption. To assess the quality of our emissions estimates, we compared our results with previous estimates which used the Global Fire Emissions Database version 3.1 (GFEDv3.1) and the Fire INventory from the National Center for Atmospheric Research version 1.0 (FINNv1), as well as Australia's National Inventory System (and its revision). The uncertainty in emission estimates was addressed using truncated Monte Carlo analysis, which derived a probability density function for total emissions from the uncertainties in each input. The distribution of emission estimates from Monte Carlo analysis was lognormal with a mean of 10,355 Gigagrams (Gg) and a ±1 standard deviation (σ) uncertainty range of 7260-13,450 Gg. Results were in good agreement with the global data sets (when using the same burnt area), although they predicted lower total emissions by 15-37% due to underestimating fuel consumed. Emissions estimates can be improved by obtaining better estimates of fuel consumed and BC emission factors. Overall, this study presents a methodological template for high-resolution emissions accounting and its uncertainty, enabling a step toward process-based emissions accounting to be achieved.

  6. Alternative ways of using field-based estimates to calibrate ecosystem models and their implications for carbon cycle studies

    Science.gov (United States)

    He, Yujie; Zhuang, Qianlai; McGuire, David; Liu, Yaling; Chen, Min

    2013-01-01

    Model-data fusion is a process in which field observations are used to constrain model parameters. How observations are used to constrain parameters has a direct impact on the carbon cycle dynamics simulated by ecosystem models. In this study, we present an evaluation of several options for the use of observations in modeling regional carbon dynamics and explore the implications of those options. We calibrated the Terrestrial Ecosystem Model on a hierarchy of three vegetation classification levels for the Alaskan boreal forest: species level, plant-functional-type level (PFT level), and biome level, and we examined the differences in simulated carbon dynamics. Species-specific field-based estimates were directly used to parameterize the model for species-level simulations, while weighted averages based on species percent cover were used to generate estimates for PFT- and biome-level model parameterization. We found that calibrated key ecosystem process parameters differed substantially among species and overlapped for species that are categorized into different PFTs. Our analysis of parameter sets suggests that the PFT-level parameterizations primarily reflected the dominant species and that functional information of some species were lost from the PFT-level parameterizations. The biome-level parameterization was primarily representative of the needleleaf PFT and lost information on broadleaf species or PFT function. Our results indicate that PFT-level simulations may be potentially representative of the performance of species-level simulations while biome-level simulations may result in biased estimates. Improved theoretical and empirical justifications for grouping species into PFTs or biomes are needed to adequately represent the dynamics of ecosystem functioning and structure.

  7. Carbon dioxide and methane measurements from the Los Angeles Megacity Carbon Project – Part 1: calibration, urban enhancements, and uncertainty estimates

    Directory of Open Access Journals (Sweden)

    K. R. Verhulst

    2017-07-01

    Full Text Available We report continuous surface observations of carbon dioxide (CO2 and methane (CH4 from the Los Angeles (LA Megacity Carbon Project during 2015. We devised a calibration strategy, methods for selection of background air masses, calculation of urban enhancements, and a detailed algorithm for estimating uncertainties in urban-scale CO2 and CH4 measurements. These methods are essential for understanding carbon fluxes from the LA megacity and other complex urban environments globally. We estimate background mole fractions entering LA using observations from four extra-urban sites including two marine sites located south of LA in La Jolla (LJO and offshore on San Clemente Island (SCI, one continental site located in Victorville (VIC, in the high desert northeast of LA, and one continental/mid-troposphere site located on Mount Wilson (MWO in the San Gabriel Mountains. We find that a local marine background can be established to within  ∼  1 ppm CO2 and  ∼  10 ppb CH4 using these local measurement sites. Overall, atmospheric carbon dioxide and methane levels are highly variable across Los Angeles. Urban and suburban sites show moderate to large CO2 and CH4 enhancements relative to a marine background estimate. The USC (University of Southern California site near downtown LA exhibits median hourly enhancements of  ∼  20 ppm CO2 and  ∼  150 ppb CH4 during 2015 as well as  ∼  15 ppm CO2 and  ∼  80 ppb CH4 during mid-afternoon hours (12:00–16:00 LT, local time, which is the typical period of focus for flux inversions. The estimated measurement uncertainty is typically better than 0.1 ppm CO2 and 1 ppb CH4 based on the repeated standard gas measurements from the LA sites during the last 2 years, similar to Andrews et al. (2014. The largest component of the measurement uncertainty is due to the single-point calibration method; however, the uncertainty in the background mole fraction is much

  8. Estimation of Carbon Flux of Forest Ecosystem over Qilian Mountains by BIOME-BGC Model

    Science.gov (United States)

    Yan, Min; Tian, Xin; Li, Zengyuan; Chen, Erxue; Li, Chunmei

    2014-11-01

    The gross primary production (GPP) and net ecosystem exchange (NEE) are important indicators for carbon fluxes. This study aims at evaluating the forest GPP and NEE over the Qilian Mountains using meteorological, remotely sensed and other ancillary data at large scale. To realize this, the widely used ecological-process-based model, Biome-BGC, and remote-sensing-based model, MODIS GPP algorithm, were selected for the simulation of the forest carbon fluxes. The combination of these two models was based on calibrating the Biome-BGC by the optimized MODIS GPP algorithm. The simulated GPP and NEE values were evaluated against the eddy covariance observed GPPs and NEEs, and the well agreements have been reached, with R2=0.76, 0.67 respectively.

  9. Efflux of rhodamine from CD56+ cells as a surrogate marker for reversal of P-glycoprotein-mediated drug efflux by PSC 833

    DEFF Research Database (Denmark)

    Robey, R; Bakke, S; Stein, W

    1999-01-01

    minutes. A dose-response relationship was shown between the concentration of PSC 833 in the blood and the inhibition of rhodamine efflux, with an apparent plateau of the inhibition of rhodamine efflux at approximately 1,000 ng/mL. The Ki, defined as the concentration required for half-maximal inhibition...... of Pgp-mediated rhodamine efflux, was determined to be in the range of 29 to 181 ng/mL; although results in two patients were distinctly different, with Ki values of 914 and 916 ng/mL. MRK-16 staining was similar among all patients. We conclude that measurement of rhodamine efflux from CD56(+) cells...

  10. Estimating the opportunity costs of reducing carbon dioxide emissions via avoided deforestation, using integrated assessment modelling

    NARCIS (Netherlands)

    Overmars, K.P.; Stehfest, E.; Tabeau, A.A.; Meijl, van J.C.M.; Beltran, A.M.; Kram, T.

    2014-01-01

    Estimates show that, in recent years, deforestation and forest degradation accounted for about 17% of global greenhouse gas emissions. The implementation of REDD (Reducing Emissions from Deforestation and Forest Degradation in Developing Countries) is suggested to provide substantial emission

  11. Identifying grain-size dependent errors on global forest area estimates and carbon studies

    Science.gov (United States)

    Daolan Zheng; Linda S. Heath; Mark J. Ducey

    2008-01-01

    Satellite-derived coarse-resolution data are typically used for conducting global analyses. But the forest areas estimated from coarse-resolution maps (e.g., 1 km) inevitably differ from a corresponding fine-resolution map (such as a 30-m map) that would be closer to ground truth. A better understanding of changes in grain size on area estimation will improve our...

  12. Accounting for behavioral effects of increases in the carbon dioxide (CO2) tax in revenue estimation in Sweden

    International Nuclear Information System (INIS)

    Hammar, Henrik; Sjoestroem, Magnus

    2011-01-01

    In this paper we describe how behavioral responses of carbon dioxide (CO 2 ) tax increases are accounted for in tax revenue estimation in Sweden. The rationale for developing a method for this is a mix between that a CO 2 tax is a primary climate policy tool aiming to reduce CO 2 emissions and that the CO 2 tax generates sizable tax revenues. - Highlights: → We develop a method on the long run tax revenue effects of increasing the CO2 tax in Sweden. → We use long run price elasticities as the basis for calculating the long run effects. → The CO2 tax is the primary instrument to reduce CO2 emissions from sectors outside the EU ETS. → There is almost an exact correlation between fossil energy use and fossil CO 2 emissions. → The method provide consistent estimates of emission reductions following from CO 2 tax increases.

  13. Rethinking CCD's Significance in Estimating Late Neogene Whole Ocean Carbonate Budget

    Science.gov (United States)

    Si, W.; Rosenthal, Y.

    2017-12-01

    The global averaged calcite compensation depth (CCD) record is conventionally used to reconstruct two correlatable parameters of the carbonate system - the alkalinity budget of the ocean and/or the saturation state of the ocean. Accordingly, the available CCD reconstructions have been interpreted to suggest either relative stable (Pearson and Palmer, 2000) or increased alkalinity of the ocean over the past 15 Ma (Tyrrell and Zeebe, 2004; Pälike et al., 2012). However, CCD alone is insufficient to constrain the carbonate system because the weathering flux of alkalinity into the ocean is not only balanced by CaCO3 dissolution on the seafloor but also by the biologic production in the euphotic zone and, the CCD records cannot be readily interpreted as changes in either process. Here, we present evidence of the co-evolution of surface CaCO3 production and deepsea dissolution through the late Neogene. By examining separately the mass accumulation rates (MAR) of coccoliths, planktonic foraminifera, and quantifying dissolution (using a proxy revised from Broecker et al., 1999) in seventeen deepsea cores from multiple depth-transects, we find that 1) MAR of dissolution-resistant coccoliths was substantially higher in the mid Miocene and declining on a global scale towards the present; 2) unlike coccoliths, MAR of planktonic foraminifera, shows no apparent secular trend through that time; 3) the revised dissolution index, shows significantly improved preservation of planktonic foraminiferal shells over that time, particularly at intermediate water depth and exhibits close association between changes in preservation with key climatic events. Our new records have two immediate implications. First, the substantially weakened pelagic biogenic carbonate production from mid Miocene to present alone could account for the improved preservation of deepsea carbonates without calling for a scenario of increased weathering input. Second, with the constrain of global averaged CCD

  14. Coupled Land Surface-Subsurface Hydrogeophysical Inverse Modeling to Estimate Soil Organic Carbon Content in an Arctic Tundra

    Science.gov (United States)

    Tran, A. P.; Dafflon, B.; Hubbard, S.

    2017-12-01

    Soil organic carbon (SOC) is crucial for predicting carbon climate feedbacks in the vulnerable organic-rich Arctic region. However, it is challenging to achieve this property due to the general limitations of conventional core sampling and analysis methods. In this study, we develop an inversion scheme that uses single or multiple datasets, including soil liquid water content, temperature and ERT data, to estimate the vertical profile of SOC content. Our approach relies on the fact that SOC content strongly influences soil hydrological-thermal parameters, and therefore, indirectly controls the spatiotemporal dynamics of soil liquid water content, temperature and their correlated electrical resistivity. The scheme includes several advantages. First, this is the first time SOC content is estimated by using a coupled hydrogeophysical inversion. Second, by using the Community Land Model, we can account for the land surface dynamics (evapotranspiration, snow accumulation and melting) and ice/liquid phase transition. Third, we combine a deterministic and an adaptive Markov chain Monte Carlo optimization algorithm to better estimate the posterior distributions of desired model parameters. Finally, the simulated subsurface variables are explicitly linked to soil electrical resistivity via petrophysical and geophysical models. We validate the developed scheme using synthetic experiments. The results show that compared to inversion of single dataset, joint inversion of these datasets significantly reduces parameter uncertainty. The joint inversion approach is able to estimate SOC content within the shallow active layer with high reliability. Next, we apply the scheme to estimate OC content along an intensive ERT transect in Barrow, Alaska using multiple datasets acquired in the 2013-2015 period. The preliminary results show a good agreement between modeled and measured soil temperature, thaw layer thickness and electrical resistivity. The accuracy of estimated SOC content

  15. Greater ATP dependence than sodium dependence of radiocalcium efflux in bullfrog ventricle

    International Nuclear Information System (INIS)

    Brommundt, G.; Kavaler, F.

    1985-01-01

    45 Ca efflux was studied in intact bullfrog ventricles following a 2-h period of loading with radiocalcium-containing Ringer solution. The cannulated ventricle was placed in a closed air-filled container to which were applied rhythmic, electronically timed, positive- and negative-pressure pulsations, which induced ventricular volume excursions. The mechanical arrangement and timing circuitry made it possible for each period to be as short in duration as 15 s. By use of this technique, penetration of the extracellular space by [ 14 C]inulin was found to be complete within 30 s, and recovery of the inulin proceeded with a time constant of 17-24 s, indicating a completeness of recovery of 98% within 90 s. Washout of added 45 Ca was quantitatively quite close to that of inulin, and in addition the estimated rate of sequestration of the isotope was slow enough to introduce only a small error into the experimental results. 45 Ca efflux was only slightly (15%) sensitive to replacement of extracellular sodium but was profoundly sensitive to the inhibitors of ATP synthesis, cyanide and 2-deoxy-glucose

  16. Virtual screening for novel Staphylococcus Aureus NorA efflux pump inhibitors from natural products.

    Science.gov (United States)

    Thai, Khac-Minh; Ngo, Trieu-Du; Phan, Thien-Vy; Tran, Thanh-Dao; Nguyen, Ngoc-Vinh; Nguyen, Thien-Hai; Le, Minh-Tri

    2015-01-01

    NorA is a member of the Major Facilitator Superfamily (MFS) drug efflux pumps that have been shown to mediate antibiotic resistance in Staphylococcus aureus (SA). In this study, QSAR analysis, virtual screening and molecular docking were implemented in an effort to discover novel SA NorA efflux pump inhibitors. Originally, a set of 47 structurally diverse compounds compiled from the literature was used to develop linear QSAR models and another set of 15 different compounds were chosen for extra validation. The final model which was estimated by statistical values for the full data set (n = 45, Q(2) = 0.80, RMSE = 0.20) and for the external test set (n = 15, R(2) = 0.60, |res|max = 0.75, |res|min = 0.02) was applied on the collection of 182 flavonoides and the traditional Chinese medicine (TCM) database to screen for novel NorA inhibitors. Finally, 33 lead compounds that met the Lipinski's rules of five/three and had good predicted pIC50 values from in silico screening process were employed to analyze the binding ability by docking studies on NorA homology model in place of its unavailable crystal structures at two active sites, the central channel and the Walker B.

  17. From models to measurements: comparing downed dead wood carbon stock estimates in the U.S. forest inventory.

    Directory of Open Access Journals (Sweden)

    Grant M Domke

    Full Text Available The inventory and monitoring of coarse woody debris (CWD carbon (C stocks is an essential component of any comprehensive National Greenhouse Gas Inventory (NGHGI. Due to the expense and difficulty associated with conducting field inventories of CWD pools, CWD C stocks are often modeled as a function of more commonly measured stand attributes such as live tree C density. In order to assess potential benefits of adopting a field-based inventory of CWD C stocks in lieu of the current model-based approach, a national inventory of downed dead wood C across the U.S. was compared to estimates calculated from models associated with the U.S.'s NGHGI and used in the USDA Forest Service, Forest Inventory and Analysis program. The model-based population estimate of C stocks for CWD (i.e., pieces and slash piles in the conterminous U.S. was 9 percent (145.1 Tg greater than the field-based estimate. The relatively small absolute difference was driven by contrasting results for each CWD component. The model-based population estimate of C stocks from CWD pieces was 17 percent (230.3 Tg greater than the field-based estimate, while the model-based estimate of C stocks from CWD slash piles was 27 percent (85.2 Tg smaller than the field-based estimate. In general, models overestimated the C density per-unit-area from slash piles early in stand development and underestimated the C density from CWD pieces in young stands. This resulted in significant differences in CWD C stocks by region and ownership. The disparity in estimates across spatial scales illustrates the complexity in estimating CWD C in a NGHGI. Based on the results of this study, it is suggested that the U.S. adopt field-based estimates of CWD C stocks as a component of its NGHGI to both reduce the uncertainty within the inventory and improve the sensitivity to potential management and climate change events.

  18. From models to measurements: comparing downed dead wood carbon stock estimates in the U.S. forest inventory.

    Science.gov (United States)

    Domke, Grant M; Woodall, Christopher W; Walters, Brian F; Smith, James E

    2013-01-01

    The inventory and monitoring of coarse woody debris (CWD) carbon (C) stocks is an essential component of any comprehensive National Greenhouse Gas Inventory (NGHGI). Due to the expense and difficulty associated with conducting field inventories of CWD pools, CWD C stocks are often modeled as a function of more commonly measured stand attributes such as live tree C density. In order to assess potential benefits of adopting a field-based inventory of CWD C stocks in lieu of the current model-based approach, a national inventory of downed dead wood C across the U.S. was compared to estimates calculated from models associated with the U.S.'s NGHGI and used in the USDA Forest Service, Forest Inventory and Analysis program. The model-based population estimate of C stocks for CWD (i.e., pieces and slash piles) in the conterminous U.S. was 9 percent (145.1 Tg) greater than the field-based estimate. The relatively small absolute difference was driven by contrasting results for each CWD component. The model-based population estimate of C stocks from CWD pieces was 17 percent (230.3 Tg) greater than the field-based estimate, while the model-based estimate of C stocks from CWD slash piles was 27 percent (85.2 Tg) smaller than the field-based estimate. In general, models overestimated the C density per-unit-area from slash piles early in stand development and underestimated the C density from CWD pieces in young stands. This resulted in significant differences in CWD C stocks by region and ownership. The disparity in estimates across spatial scales illustrates the complexity in estimating CWD C in a NGHGI. Based on the results of this study, it is suggested that the U.S. adopt field-based estimates of CWD C stocks as a component of its NGHGI to both reduce the uncertainty within the inventory and improve the sensitivity to potential management and climate change events.

  19. Differences on soil organic carbon stock estimation according to sampling type in Mediterranean areas

    Science.gov (United States)

    Parras-Alcántara, Luis; Lozano-García, Beatriz

    2016-04-01

    Soil organic carbon (SOC) is an important part of the global carbon (C) cycle. In addition, SOC is a soil property subject to changes and highly variable in space and time. Consequently, the scientific community is researching the fate of the organic carbon in the ecosystems. In this line, soil organic matter configuration plays an important role in the Soil System (Parras-Alcántara and Lozano García, 2014). Internationally it is known that soil C sequestration is a strategy to mitigate climate change. In this sense, many soil researchers have studied this parameter (SOC). However, many of these studies were carried out arbitrarily using entire soil profiles (ESP) by pedogenetic horizons or soil control sections (SCS) (edaphic controls to different thickness). As a result, the indiscriminate use of both methodologies implies differences with respect to SOC stock (SOCS) quantification. This scenario has been indicated and warned for different researchers (Parras-Alcántara et al., 2015a; Parras-Alcántara et al., 2015b). This research sought to analyze the SOC stock (SOCS) variability using both methods (ESP and SCS) in the Cardeña and Montoro Natural Park (Spain). This nature reserve is a forested area with 385 km2 in southern Spain. Thirty-seven sampling points were selected in the study zone. Each sampling point was analyzed in two different ways, as ESP (by horizons) and as SCS with different depth increments (0-25, 25-50, 50-75 and 75-100 cm). The major goal of this research was to study the SOCS variability at regional scale. The studied soils were classified as Phaeozems, Cambisols, Regosols and Leptosols. The results obtained show an overestimation of SOCS when SCS sampling approach is used compared to ESP. This supports that methodology selection is very important to SOCS quantification. This research is an assessment for modeling SOCS at the regional level in Mediterranean natural areas. References Parras-Alcántara, L., Lozano-García, B., 2014

  20. Geological Carbon Sequestration Storage Resource Estimates for the Ordovician St. Peter Sandstone, Illinois and Michigan Basins, USA

    Energy Technology Data Exchange (ETDEWEB)

    Barnes, David; Ellett, Kevin; Leetaru, Hannes

    2014-09-30

    The Cambro-Ordovician strata of the Midwest of the United States is a primary target for potential geological storage of CO2 in deep saline formations. The objective of this project is to develop a comprehensive evaluation of the Cambro-Ordovician strata in the Illinois and Michigan Basins above the basal Mount Simon Sandstone since the Mount Simon is the subject of other investigations including a demonstration-scale injection at the Illinois Basin Decatur Project. The primary reservoir targets investigated in this study are the middle Ordovician St Peter Sandstone and the late Cambrian to early Ordovician Knox Group carbonates. The topic of this report is a regional-scale evaluation of the geologic storage resource potential of the St Peter Sandstone in both the Illinois and Michigan Basins. Multiple deterministic-based approaches were used in conjunction with the probabilistic-based storage efficiency factors published in the DOE methodology to estimate the carbon storage resource of the formation. Extensive data sets of core analyses and wireline logs were compiled to develop the necessary inputs for volumetric calculations. Results demonstrate how the range in uncertainty of storage resource estimates varies as a function of data availability and quality, and the underlying assumptions used in the different approaches. In the simplest approach, storage resource estimates were calculated from mapping the gross thickness of the formation and applying a single estimate of the effective mean porosity of the formation. Results from this approach led to storage resource estimates ranging from 3.3 to 35.1 Gt in the Michigan Basin, and 1.0 to 11.0 Gt in the Illinois Basin at the P10 and P90 probability level, respectively. The second approach involved consideration of the diagenetic history of the formation throughout the two basins and used depth-dependent functions of porosity to derive a more realistic spatially variable model of porosity rather than applying a

  1. Estimation of carbonate concentration and characterization of marine sediments by Fourier transform infrared spectroscopy.

    Digital Repository Service at National Institute of Oceanography (India)

    Veerasingam, S.; Venkatachalapathy, R.

    its saturation horizon is shallower than that calcite [1]. Elements such as Ca2+ and Mg2+, in addition to their substantial contribution to marine sediments, are used biologically in vital cellular processes and in the mineralization of skeletons... such as ocean acidification on ecosystems. Thus, a rapid, cheap and non-destructive tool is required to investigate the distribution of CaCO3 in sediments for the understanding of the fate of biologically produced carbonate. 3    FTIR spectroscopy is one...

  2. Large nonlinear absorption and refraction coefficients of carbon nanotubes estimated from femtosecond z-scan measurements

    Science.gov (United States)

    Kamaraju, N.; Kumar, Sunil; Sood, A. K.; Guha, Shekhar; Krishnamurthy, Srinivasan; Rao, C. N. R.

    2007-12-01

    Nonlinear transmission of 80 and 140fs pulsed light with 0.79μm wavelength through single walled carbon nanotubes suspended in water containing sodium dodecyl sulfate is studied. Pulse-width independent saturation absorption and negative cubic nonlinearity are observed, respectively, in open and closed aperture z-scan experiments. The theoretical expressions derived to analyze the z-dependent transmission in the saturable limit require two photon absorption coefficient β0˜1.4cm/MW and a nonlinear index γ ˜-5.5×10-11cm2/W to fit the data.

  3. Temporal Decorrelation Effect in Carbon Stocks Estimation Using Polarimetric Interferometry Synthetic Aperture Radar (PolInSAR (Case Study: Southeast Sulawesi Tropical Forest

    Directory of Open Access Journals (Sweden)

    Laode M Golok Jaya

    2017-07-01

    Full Text Available This paper was aimed to analyse the effect of temporal decorrelation in carbon stocks estimation. Estimation of carbon stocks plays important roles particularly to understand the global carbon cycle in the atmosphere regarding with climate change mitigation effort. PolInSAR technique combines the advantages of Polarimetric Synthetic Aperture Radar (PolSAR and Interferometry Synthetic Aperture Radar (InSAR technique, which is evidenced to have significant contribution in radar mapping technology in the last few years. In carbon stocks estimation, PolInSAR provides information about vertical vegetation structure to estimate carbon stocks in the forest layers. Two coherence Synthetic Aperture Radar (SAR images of ALOS PALSAR full-polarimetric with 46 days temporal baseline were used in this research. The study was carried out in Southeast Sulawesi tropical forest. The research method was by comparing three interferometric phase coherence images affected by temporal decorrelation and their impacts on Random Volume over Ground (RvoG model. This research showed that 46 days temporal baseline has a significant impact to estimate tree heights of the forest cover where the accuracy decrease from R2=0.7525 (standard deviation of tree heights is 2.75 meters to R2=0.4435 (standard deviation 4.68 meters and R2=0.3772 (standard deviation 3.15 meters respectively. However, coherence optimisation can provide the best coherence image to produce a good accuracy of carbon stocks.

  4. Estimating carbonate parameters from hydrographic data for the intermediate and deep waters of the Southern Hemisphere oceans

    Science.gov (United States)

    Bostock, H. C.; Mikaloff Fletcher, S. E.; Williams, M. J. M.

    2013-10-01

    Using ocean carbon data from global datasets, we have developed several multiple linear regression (MLR) algorithms to estimate alkalinity and dissolved inorganic carbon (DIC) in the intermediate and deep waters of the Southern Hemisphere (south of 25° S) from only hydrographic data (temperature, salinity and dissolved oxygen). A Monte Carlo experiment was used to identify a potential density (σθ) of 27.5 as an optimal break point between the two regimes with different MLR algorithms. The algorithms provide a good estimate of DIC (R2=0.98) and alkalinity (R2=0.91), and excellent agreement for aragonite and calcite saturation states (R2=0.99). Combining the algorithms with the CSIRO Atlas of Regional Seas (CARS), we have mapped the calcite saturation horizon (CSH) and aragonite saturation horizon (ASH) for the Southern Ocean at a spatial resolution of 0.5°. These maps are more detailed and more consistent with the oceanography than the previously gridded GLODAP data. The high-resolution ASH map reveals a dramatic circumpolar shoaling at the polar front. North of 40° S the CSH is deepest in the Atlantic (~ 4000 m) and shallower in the Pacific Ocean (~ 2750 m), while the CSH sits between 3200 and 3400 m in the Indian Ocean. The uptake of anthropogenic carbon by the ocean will alter the relationships between DIC and hydrographic data in the intermediate and deep waters over time. Thus continued sampling will be required, and the MLR algorithms will need to be adjusted in the future to account for these changes.

  5. Estimating carbonate parameters from hydrographic data for the intermediate and deep waters of the Southern Hemisphere oceans

    Directory of Open Access Journals (Sweden)

    H. C. Bostock

    2013-10-01

    Full Text Available Using ocean carbon data from global datasets, we have developed several multiple linear regression (MLR algorithms to estimate alkalinity and dissolved inorganic carbon (DIC in the intermediate and deep waters of the Southern Hemisphere (south of 25° S from only hydrographic data (temperature, salinity and dissolved oxygen. A Monte Carlo experiment was used to identify a potential density (σθ of 27.5 as an optimal break point between the two regimes with different MLR algorithms. The algorithms provide a good estimate of DIC (R2=0.98 and alkalinity (R2=0.91, and excellent agreement for aragonite and calcite saturation states (R2=0.99. Combining the algorithms with the CSIRO Atlas of Regional Seas (CARS, we have mapped the calcite saturation horizon (CSH and aragonite saturation horizon (ASH for the Southern Ocean at a spatial resolution of 0.5°. These maps are more detailed and more consistent with the oceanography than the previously gridded GLODAP data. The high-resolution ASH map reveals a dramatic circumpolar shoaling at the polar front. North of 40° S the CSH is deepest in the Atlantic (~ 4000 m and shallower in the Pacific Ocean (~ 2750 m, while the CSH sits between 3200 and 3400 m in the Indian Ocean. The uptake of anthropogenic carbon by the ocean will alter the relationships between DIC and hydrographic data in the intermediate and deep waters over time. Thus continued sampling will be required, and the MLR algorithms will need to be adjusted in the future to account for these changes.

  6. Estimating the implied cost of carbon in future scenarios using a CGE model: The Case of Colorado

    International Nuclear Information System (INIS)

    Hannum, Christopher; Cutler, Harvey; Iverson, Terrence; Keyser, David

    2017-01-01

    Using Colorado as a case study, we develop a state-level computable general equilibrium (CGE) model that reflects the roles of coal, natural gas, wind, solar, and hydroelectricity in supplying electricity. We focus on the economic impact of implementing Colorado's existing Renewable Portfolio Standard, updated in 2013. This requires that 25% of state generation come from qualifying renewable sources by 2020. We evaluate the policy under a variety of assumptions regarding wind integration costs and assumptions on the persistence of federal subsidies for wind. Specifically, we estimate the implied price of carbon as the carbon price at which a state-level policy would pass a state-level cost-benefit analysis, taking account of estimated greenhouse gas emission reductions and ancillary benefits from corresponding reductions in criteria pollutants. Our findings suggest that without the Production Tax Credit (federal aid), the state policy of mandating renewable power generation (RPS) is costly to state actors, with an implied cost of carbon of about $17 per ton of CO2 with a 3% discount rate. Federal aid makes the decision between natural gas and wind nearly cost neutral for Colorado. - Highlights: • If variability cost is low and renewables are federally subsidized, RPS is beneficial. • With no PTC or high variability cost, drop in real consumption less than 0.1%. • With PTC phaseout and high variability cost ICP is low, between $7.16 and $11.45. • With no PTC and high variability cost ICP is between $12.66 and $17.34 per ton.

  7. An estimate of the terrestrial carbon budget of Russia using inventory-based, eddy covariance and inversion methods

    Directory of Open Access Journals (Sweden)

    A. J. Dolman

    2012-12-01

    Full Text Available We determine the net land to atmosphere flux of carbon in Russia, including Ukraine, Belarus and Kazakhstan, using inventory-based, eddy covariance, and inversion methods. Our high boundary estimate is −342 Tg C yr−1 from the eddy covariance method, and this is close to the upper bounds of the inventory-based Land Ecosystem Assessment and inverse models estimates. A lower boundary estimate is provided at −1350 Tg C yr−1 from the inversion models. The average of the three methods is −613.5 Tg C yr−1. The methane emission is estimated separately at 41.4 Tg C yr−1.

    These three methods agree well within their respective error bounds. There is thus good consistency between bottom-up and top-down methods. The forests of Russia primarily cause the net atmosphere to land flux (−692 Tg C yr−1 from the LEA. It remains however remarkable that the three methods provide such close estimates (−615, −662, −554 Tg C yr–1 for net biome production (NBP, given the inherent uncertainties in all of the approaches. The lack of recent forest inventories, the few eddy covariance sites and associated uncertainty with upscaling and undersampling of concentrations for the inversions are among the prime causes of the uncertainty. The dynamic global vegetation models (DGVMs suggest a much lower uptake at −91 Tg C yr−1, and we argue that this is caused by a high estimate of heterotrophic respiration compared to other methods.

  8. Estimating Global Seafloor Total Organic Carbon Using a Machine Learning Technique and Its Relevance to Methane Hydrates

    Science.gov (United States)

    Lee, T. R.; Wood, W. T.; Dale, J.

    2017-12-01

    Empirical and theoretical models of sub-seafloor organic matter transformation, degradation and methanogenesis require estimates of initial seafloor total organic carbon (TOC). This subsurface methane, under the appropriate geophysical and geochemical conditions may manifest as methane hydrate deposits. Despite the importance of seafloor TOC, actual observations of TOC in the world's oceans are sparse and large regions of the seafloor yet remain unmeasured. To provide an estimate in areas where observations are limited or non-existent, we have implemented interpolation techniques that rely on existing data sets. Recent geospatial analyses have provided accurate accounts of global geophysical and geochemical properties (e.g. crustal heat flow, seafloor biomass, porosity) through machine learning interpolation techniques. These techniques find correlations between the desired quantity (in this case TOC) and other quantities (predictors, e.g. bathymetry, distance from coast, etc.) that are more widely known. Predictions (with uncertainties) of seafloor TOC in regions lacking direct observations are made based on the correlations. Global distribution of seafloor TOC at 1 x 1 arc-degree resolution was estimated from a dataset of seafloor TOC compiled by Seiter et al. [2004] and a non-parametric (i.e. data-driven) machine learning algorithm, specifically k-nearest neighbors (KNN). Built-in predictor selection and a ten-fold validation technique generated statistically optimal estimates of seafloor TOC and uncertainties. In addition, inexperience was estimated. Inexperience is effectively the distance in parameter space to the single nearest neighbor, and it indicates geographic locations where future data collection would most benefit prediction accuracy. These improved geospatial estimates of TOC in data deficient areas will provide new constraints on methane production and subsequent methane hydrate accumulation.

  9. Glutamate Efflux at the Blood-Brain Barrier

    DEFF Research Database (Denmark)

    Cederberg-Helms, Hans Christian; Uhd-Nielsen, Carsten; Brodin, Birger

    2014-01-01

    is well known, however endothelial cells may also play an important role through mediating brain-to-blood L-glutamate efflux. Expression of excitatory amino acid transporters has been demonstrated in brain endothelial cells of bovine, human, murine, rat and porcine origin. These can account for high...... affinity concentrative uptake of L-glutamate from the brain interstitial fluid into the capillary endothelial cells. The mechanisms in between L-glutamate uptake in the endothelial cells and L-glutamate appearing in the blood are still unclear and may involve a luminal transporter for L......-glutamate, metabolism of L-glutamate and transport of metabolites or a combination of the two. However, both in vitro and in vivo studies have demonstrated blood-to-brain transport of L-glutamate, at least during pathological events. This review summarizes the current knowledge on the brain-to-blood L-glutamate efflux...

  10. Computer simulations of the activity of RND efflux pumps.

    Science.gov (United States)

    Vargiu, Attilio Vittorio; Ramaswamy, Venkata Krishnan; Malloci, Giuliano; Malvacio, Ivana; Atzori, Alessio; Ruggerone, Paolo

    2018-01-31

    The putative mechanism by which bacterial RND-type multidrug efflux pumps recognize and transport their substrates is a complex and fascinating enigma of structural biology. How a single protein can recognize a huge number of unrelated compounds and transport them through one or just a few mechanisms is an amazing feature not yet completely unveiled. The appearance of cooperativity further complicates the understanding of structure-dynamics-activity relationships in these complex machineries. Experimental techniques may have limited access to the molecular determinants and to the energetics of key processes regulating the activity of these pumps. Computer simulations are a complementary approach that can help unveil these features and inspire new experiments. Here we review recent computational studies that addressed the various molecular processes regulating the activity of RND efflux pumps. Copyright © 2018 The Authors. Published by Elsevier Masson SAS.. All rights reserved.

  11. Intensive management modifies soil CO2 efflux in 6-year-old Pinus taeda L. stands

    Science.gov (United States)

    Lisa J. Samuelson; Kurt Johnsen; Tom Stokes; Weinlang Lu

    2004-01-01

    Intensive forestry may reduce net CO2 emission into atmosphere by storing carbon in living biomass, dead organic matter and soil, and durable wood products. Because quantification of belowground carbon dynamics is important for reliable estimation of the carbon sequestered by intensively managed plantations, we examined soil CO2...

  12. C-Lock: An online system to standardize the estimation of agricultural carbon sequestration credits

    Energy Technology Data Exchange (ETDEWEB)

    Updegraff, Karen; Zimmerman, Patrick R.; Capehart, William J. [Institute of Atmospheric Sciences, South Dakota School of Mines and Technology, 501 E. St. Joseph Street, Rapid City, SD 57701-3995 (United States); Price, Maribeth [Department of Geology, South Dakota School of Mines and Technology, 501 E. St. Joseph Street, Rapid City, SD 57701-3995 (United States)

    2005-10-15

    C-Lock (patent pending) is a system that has been designed to produce standardized carbon emission reduction credits (CERCs) that minimize litigation risks to purchasers and maximize the potential value to agricultural producers. C-Lock provides a web-based user interface linking producer-supplied, verifiable, management data, a detailed regional-scale GIS, and a biogeochemical model (CENTURY). Output includes historical incremental carbon sequestration since 1990 and predictions of future sequestration, packaged to satisfy evolving regulatory standards. C-Lock incorporates a unique uncertainty analysis and a three-level verification system to produce certified CERCs for specific land parcels in a way that is reproducible, equitable, and regionally defensible. Using a South Dakota farm as an example, the authors show how, by avoiding reliance on field sampling, this system can minimize measurement and monitoring costs. It allows individual producers a high degree of control over contract design and marketing, thereby reducing transaction costs. The transparent, standardized, and auditable procedure produces CERCs of maximum value to those seeking emission offsets. (author)

  13. Estimating Carbon Stocks and Atmospheric Exchange of Depressional Marshes on the Central Florida Landscape

    Science.gov (United States)

    Benscoter, B.; McClellan, M. D.; Benavides, V.; Harshbarger, D.; Comas, X.

    2014-12-01

    Depressional marshes are ubiquitous throughout central and south Florida. Often distributed within a matrix of sandy pine flatwoods and hammocks, these wetlands have a seasonally variable water table, alternating between inundation and complete drydown. Though these landforms are typically small individually, they comprise a substantial component of the landscape and provide vital habitat for an array of flora and fauna. Given their fluctuating hydrology, conditions for soil and plant carbon (C) exchange mechanisms can vary greatly both spatially and temporally. In this study, we are developing a C budget for depressional marsh landforms by assessing ecosystem carbon exchange along an ecotone gradient and quantifying belowground C stocks using non-invasive geophysical methods (ground penetrating radar, GPR) at the Disney Wilderness Preserve (DWP) in Kissimmee, FL, USA. Using a series of closed chambers transecting the marsh from the center outward into the surrounding flatwoods, we are quantifying the effects of seasonal water table change on the magnitude of C exchange. Three dimensional GPR surveys were used to quantify peat layer thickness, and were constrained with direct core sampling to verify subsurface lithology and to assess peat C content. Using the relationship between landform surface area and belowground C volume, we assessed the cumulative C storage in depressional marshes across the DWP landscape. In conjunction with a nearby eddy covariance tower and seasonal hydrologic data, these response functions will help to evaluate the contribution of these small but widespread landscape features on regional C cycling.

  14. Estimating Soil Organic Carbon Sequestration in Rice Paddies as Influenced by Climate Change under Scenario A2 and B2 of an i-EPIC model of Thailand

    Directory of Open Access Journals (Sweden)

    Noppol Arunrat

    2014-01-01

    Full Text Available Carbon sequestration in soils constitutes an important option that can be used to reduce CO2 emissions to the atmosphere and reduce environmental impacts. Soil organic carbon (SOC is both a source of carbon release and a sink for carbon sequestration. Our objectives in this study were to validate the interactive Environmental Policy Impact Calculator (i-EPIC model version 0509, as well as to estimate SOC sequestration under climate change scenarios A2 and B2 SRES emission scenarios in Thailand. The SOC estimated by i-EPIC was compared with data from the Office of Soil Resources Survey and Research, Land Development Department. The results indicated that performance testing of i-EPIC is able to estimate SOC. Validation of SOC proved to be satisfactory with a resulting root mean square error (RMSE % value of 34.60. The SOC content showed a decreasing trend under B2 and A2 climate scenarios (average 0.87% and 0.85%, respectively compared to the reference from 2007 (average 0.92%. Stepwise regression analysis also revealed that carbon from residue decomposition, biomass pool carbon, and the total change of the carbon pool were directly correlated with the SOC (R2= 0.99, p< 0.01. Furthermore, the change from rain supplied water to irrigation also resulted in an increase of carbon inputs but a decrease in the SOC sequestered during the 2007-2017 period. Regression analyses indicated that soil carbon sequestration responds linearly to carbon input. Significant changes in carbon input as well as decreases in SOC levels were observed as temperature and precipitation increased. Based on the testing and analysis, we concluded that i-EPIC is capable of reliably simulating effects of climate change on SOC sequestration. Based on the results, this knowledge and information can increase effectiveness in the promotion of integrated rice management for rice production in Thailand.

  15. Using NDVI to estimate carbon fluxes from small rotationally grazed pastures

    Science.gov (United States)

    Satellite-based Normalized Difference Vegetation Index (NDVI) data have been extensively used for estimating gross primary productivity (GPP) and yield of grazing lands throughout the world. However, the usefulness of satellite-based images for monitoring rotationally-grazed pastures in the northea...

  16. Interannual variability of carbon monoxide emission estimates over South America from 2006 to 2010

    NARCIS (Netherlands)

    Hooghiemstra, P.B.; Krol, M.C.; Leeuwen, van T.T.; Werf, van der G.R.; Novelli, P.C.; Deeter, M.N.; Aben, I.; Rockmann, T.

    2012-01-01

    We present the first inverse modeling study to estimate CO emissions constrained by both surface and satellite observations. Our 4D-Var system assimilates National Oceanic and Atmospheric Administration Earth System Research Laboratory (NOAA/ESRL) Global Monitoring Division (GMD) surface and

  17. Do Phytotropins Inhibit Auxin Efflux by Impairing Vesicle Traffic?

    Czech Academy of Sciences Publication Activity Database

    Petrášek, Jan; Černá, A.; Schwarzerová, K.; Elčkner, Miroslav; Morris, David; Zažímalová, Eva

    2003-01-01

    Roč. 131, č. 1 (2003), s. 254-263 ISSN 0032-0889 R&D Projects: GA MŠk LN00A081 Grant - others:EU INCO COPERNICUS(XE) ERBIC15 CT98 0118 Institutional research plan: CEZ:AV0Z5038910 Keywords : 1-N-naphthylphthalamic acid * BY-2 tobacco * auxin efflux Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 5.634, year: 2003

  18. Enhanced Efflux Pump Activity in Old Candida glabrata Cells.

    Science.gov (United States)

    Bhattacharya, Somanon; Fries, Bettina C

    2018-03-01

    We investigated the effect of replicative aging on antifungal resistance in Candida glabrata Our studies demonstrate significantly increased transcription of ABC transporters and efflux pump activity in old versus young C. glabrata cells of a fluconazole-sensitive and -resistant strain. In addition, higher tolerance to killing by micafungin and amphotericin B was noted and is associated with higher transcription of glucan synthase gene FKS1 and lower ergosterol content in older cells. Copyright © 2018 American Society for Microbiology.

  19. Multidrug Efflux Pumps in Staphylococcus aureus: an Update

    OpenAIRE

    Costa, Sofia Santos; Viveiros, Miguel; Amaral, Leonard; Couto, Isabel

    2013-01-01

    The emergence of infections caused by multi- or pan-resistant bacteria in the hospital or in the community settings is an increasing health concern. Albeit there is no single resistance mechanism behind multiresistance, multidrug efflux pumps, proteins that cells use to detoxify from noxious compounds, seem to play a key role in the emergence of these multidrug resistant (MDR) bacteria. During the last decades, experimental data has established their contribution to low level resistance to an...

  20. On Estimation of Contamination from Hydrogen Cyanide in Carbon Monoxide Line-intensity Mapping

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Dongwoo T.; Li, Tony Y.; Viero, Marco P.; Church, Sarah E.; Wechsler, Risa H., E-mail: dongwooc@stanford.edu [Kavli Institute for Particle Astrophysics and Cosmology, Physics Department, Stanford University, Stanford, CA 94305 (United States)

    2017-09-01

    Line-intensity mapping surveys probe large-scale structure through spatial variations in molecular line emission from a population of unresolved cosmological sources. Future such surveys of carbon monoxide line emission, specifically the CO(1-0) line, face potential contamination from a disjointed population of sources emitting in a hydrogen cyanide emission line, HCN(1-0). This paper explores the potential range of the strength of HCN emission and its effect on the CO auto power spectrum, using simulations with an empirical model of the CO/HCN–halo connection. We find that effects on the observed CO power spectrum depend on modeling assumptions but are very small for our fiducial model, which is based on current understanding of the galaxy–halo connection. Given the fiducial model, we expect the bias in overall CO detection significance due to HCN to be less than 1%.

  1. Estimates of Eastern Equatorial Pacific Sea Surface Temperatures During the Pliocene From Carbonate 'Clumped Isotope' Thermometry

    Science.gov (United States)

    Thiagarajan, N.; Tripati, A.; Eiler, J.

    2007-12-01

    The early Pliocene (5 to 3 Ma) was an interval in Earth history that was globally warmer than the present; thus, study of the details of Pliocene climate can provide insights into the dynamics of warm climates. There are two competing models of the temperature structure of the tropical Pacific upper-ocean during the early Pliocene: the dynamical 'ocean thermostat' model [1,2] and the 'El Padre' (or permanent 'El Nino') model [3], each of which predict zonal temperature gradients and mean conditions in the Eastern Equatorial Pacific (EEP), and which differ markedly from one another in these predictions. The dynamical 'ocean thermostat' model predicts an increased temperature contrast between the Western Equatorial Pacific (WEP) and EEP, enhanced thermocline tilt and intensified upwelling under warmer conditions. In contrast, the 'El Padre' model postulates a collapse of the zonal temperature gradient, reduced thermocline tilt and a reduction in upwelling and/or warmer temperatures of upwelled waters. Existing reconstructions of tropical temperatures produce WEP sea surface temperatures which agree with each other, but yield very different results in the EEP [4,5]. We have reconstructed EEP sea surface temperatures at Ocean Drilling Program (ODP) Site 847 using a few samples spanning key intervals of the last 6 million years using carbonate clumped isotope thermometer [6,7,8]. This technique is based on the temperature dependence of the abundances of 13C-18O bonds in carbonate minerals. Initial measurements of planktonic foraminifera and coccoliths from ODP Site 847 indicate cool EEP sea surface temperatures, supporting models of Pliocene climate that have enhanced zonal temperature gradients, relative to modern. Analyses of Globigerinoides sacculifer (with sac) from sediments indicate calcification temperatures of 20.3°C ± 0.1°C and seawater δ18O values of -0.8‰ ± 0.1‰ from ~6.1 to 5.1 million years ago. Measurements of a mixed coccolith assemblage from the

  2. Estimation of the soil-water partition coefficient normalized to organic carbon for ionizable organic chemicals

    DEFF Research Database (Denmark)

    Franco, Antonio; Trapp, Stefan

    2008-01-01

    The sorption of organic electrolytes to soil was investigated. A dataset consisting of 164 electrolytes, composed of 93 acids, 65 bases, and six amphoters, was collected from literature and databases. The partition coefficient log KOW of the neutral molecule and the dissociation constant pKa were...... calculated by the software ACD/Labs®. The Henderson-Hasselbalch equation was applied to calculate dissociation. Regressions were developed to predict separately for the neutral and the ionic molecule species the distribution coefficient (Kd) normalized to organic carbon (KOC) from log KOW and pKa. The log...... KOC of strong acids (pKa correlated to these parameters. The regressions derived for weak acids and bases (undissociated at environmental pH) were similar. The highest sorption was found for strong bases (pKa > 7.5), probably due to electrical interactions. Nonetheless, their log KOC...

  3. Estimation of niobium, tantalum and zirconium in a carbonate rich ore

    International Nuclear Information System (INIS)

    Navale, A.S.; Venkatakrishnan, R.R.; Sreenivas, T.

    2013-01-01

    Tantalum, niobium and zirconium form refractory compounds and therefore pose problems in estimation by methods like spectrophotometry, AAS etc. Their estimation is best carried out with ICP-OES as the plasma is capable of breaking the refractory compounds and releases these elements in the form of excited atoms. But another major problem is bringing these elements in solution as they require very strong reagents and tend to hydrolyze easily in solution. Complexing agents need to be added to maintain these elements in dissolved condition. The commonly employed dissolution techniques for these elements are fusion with potassium pyrosulfate (for Nb and Ta), sodium hydroxide or peroxide (for zirconium). Digestion with mineral acids in combination with hydrofluoric acid is also employed

  4. Estimating agro-ecosystem carbon balance of northern Japan, and comparing the change in carbon stock by soil inventory and net biome productivity.

    Science.gov (United States)

    Li, Xi; Toma, Yo; Yeluripati, Jagadeesh; Iwasaki, Shinya; Bellingrath-Kimura, Sonoko D; Jones, Edward O; Hatano, Ryusuke

    2016-06-01

    Soil C sequestration in croplands is deemed to be one of the most promising greenhouse gas mitigation options for agriculture. We have used crop-level yields, modeled heterotrophic respiration (Rh) and land use data to estimate spatio-temporal changes in regional scale net primary productivity (NPP), plant C inputs, and net biome productivity (NBP) in northern Japan's arable croplands and grasslands for the period of 1959-2011. We compared the changes in C stocks derived from estimated NBP and using repeated inventory datasets for each individual land use type from 2005 to 2011. For the entire study region of 2193 ha, overall annual plant C inputs to the soil constituted 37% of total region NPP. Plant C inputs in upland areas (excluding bush/fallow) could be predicted by climate variables. Overall NBP for all land use types increased from -1.26MgCha(-1)yr(-1) in 1959-0.26 Mg Cha(-1)yr(-1) in 2011. However, upland and paddy fields showed a decreased in NBP over the period of 1959-2011, under the current C input scenario. From 1988, an increase in agricultural abandonment (bush/fallow) and grassland cover caused a slow increase in the regional C pools. The comparison of carbon budgets using the NBP estimation method and the soil inventory method indicated no significant difference between the two methods. Our results showed C loss in upland crops, paddy fields and sites that underwent land use change from paddy field to upland sites. We also show C gain in grassland from 2005 to 2011. An underestimation of NBP or an overestimation of repeated C inventories cannot be excluded, but either method may be suitable for tracking absolute changes in soil C, considering the uncertainty associated with these methods. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Improving the Carbon Dioxide Emission Estimates from the Combustion of Fossil Fuels in California

    Energy Technology Data Exchange (ETDEWEB)

    de la Rue du Can, Stephane; Wenzel, Tom; Price, Lynn

    2008-08-13

    Central to any study of climate change is the development of an emission inventory that identifies and quantifies the State's primary anthropogenic sources and sinks of greenhouse gas (GHG) emissions. CO2 emissions from fossil fuel combustion accounted for 80 percent of California GHG emissions (CARB, 2007a). Even though these CO2 emissions are well characterized in the existing state inventory, there still exist significant sources of uncertainties regarding their accuracy. This report evaluates the CO2 emissions accounting based on the California Energy Balance database (CALEB) developed by Lawrence Berkeley National Laboratory (LBNL), in terms of what improvements are needed and where uncertainties lie. The estimated uncertainty for total CO2 emissions ranges between -21 and +37 million metric tons (Mt), or -6percent and +11percent of total CO2 emissions. The report also identifies where improvements are needed for the upcoming updates of CALEB. However, it is worth noting that the California Air Resources Board (CARB) GHG inventory did not use CALEB data for all combustion estimates. Therefore the range in uncertainty estimated in this report does not apply to the CARB's GHG inventory. As much as possible, additional data sources used by CARB in the development of its GHG inventory are summarized in this report for consideration in future updates to CALEB.

  6. Circumpolar assessment of rhizosphere priming shows limited increase in carbon loss estimates for permafrost soils but large regional variability

    Science.gov (United States)

    Wild, B.; Keuper, F.; Kummu, M.; Beer, C.; Blume-Werry, G.; Fontaine, S.; Gavazov, K.; Gentsch, N.; Guggenberger, G.; Hugelius, G.; Jalava, M.; Koven, C.; Krab, E. J.; Kuhry, P.; Monteux, S.; Richter, A.; Shazhad, T.; Dorrepaal, E.

    2017-12-01

    Predictions of soil organic carbon (SOC) losses in the northern circumpolar permafrost area converge around 15% (± 3% standard error) of the initial C pool by 2100 under the RCP 8.5 warming scenario. Yet, none of these estimates consider plant-soil interactions such as the rhizosphere priming effect (RPE). While laboratory experiments have shown that the input of plant-derived compounds can stimulate SOC losses by up to 1200%, the magnitude of RPE in natural ecosystems is unknown and no methods for upscaling exist so far. We here present the first spatial and depth explicit RPE model that allows estimates of RPE on a large scale (PrimeSCale). We combine available spatial data (SOC, C/N, GPP, ALT and ecosystem type) and new ecological insights to assess the importance of the RPE at the circumpolar scale. We use a positive saturating relationship between the RPE and belowground C allocation and two ALT-dependent rooting-depth distribution functions (for tundra and boreal forest) to proportionally assign belowground C allocation and RPE to individual soil depth increments. The model permits to take into account reasonable limiting factors on additional SOC losses by RPE including interactions between spatial and/or depth variation in GPP, plant root density, SOC stocks and ALT. We estimate potential RPE-induced SOC losses at 9.7 Pg C (5 - 95% CI: 1.5 - 23.2 Pg C) by 2100 (RCP 8.5). This corresponds to an increase of the current permafrost SOC-loss estimate from 15% of the initial C pool to about 16%. If we apply an additional molar C/N threshold of 20 to account for microbial C limitation as a requirement for the RPE, SOC losses by RPE are further reduced to 6.5 Pg C (5 - 95% CI: 1.0 - 16.8 Pg C) by 2100 (RCP 8.5). Although our results show that current estimates of permafrost soil C losses are robust without taking into account the RPE, our model also highlights high-RPE risk in Siberian lowland areas and Alaska north of the Brooks Range. The small overall impact of

  7. Reduced tillage and cover crops as a strategy for mitigating atmospheric CO2 increase through soil organic carbon sequestration in dry Mediterranean agroecosystems.

    Science.gov (United States)

    Almagro, María; Garcia-Franco, Noelia; de Vente, Joris; Boix-Fayos, Carolina; Díaz-Pereira, Elvira; Martínez-Mena, María

    2016-04-01

    The implementation of sustainable land management (SLM) practices in semiarid Mediterranean agroecosystems can be beneficial to maintain or enhance levels of soil organic carbon and mitigate current atmospheric CO2 increase. In this study, we assess the effects of different tillage treatments (conventional tillage (CT), reduced tillage (RT), reduced tillage combined with green manure (RTG), and no tillage (NT)) on soil CO2 efflux, aggregation and organic carbon stabilization in two semiarid organic rainfed almond (Prunus dulcis Mill., var. Ferragnes) orchards located in SE Spain Soil CO2 efflux, temperature and moisture were measured monthly between May 2012 and December 2014 (site 1), and between February 2013 and December 2014 (site 2). In site 1, soil CO2 efflux rates were also measured immediately following winter and spring tillage operations. Aboveground biomass inputs were estimated at the end of the growing season in each tillage treatment. Soil samples (0-15 cm) were collected in the rows between the trees (n=4) in October 2012. Four aggregate size classes were distinguished by sieving (large and small macroaggregates, free microaggregates, and free silt plus clay fraction), and the microaggregates occluded within macroaggregates (SMm) were isolated. Soil CO2efflux rates in all tillage treatments varied significantly during the year, following changes during the autumn, winter and early spring, or changes in soil moisture during late spring and summer. Repeated measures analyses of variance revealed that there were no significant differences in soil CO2 efflux between tillage treatments throughout the study period at both sites. Average annual values of C lost by soil respiration were slightly but not significantly higher under RT and RTG treatments (492 g C-CO2 m-2 yr-1) than under NT treatment (405 g C-CO2 m-2 yr-1) in site 1, while slightly but not significantly lower values were observed under RT and RTG treatments (468 and 439 g C-CO2 m-2 yr-1

  8. Tangshen Formula Attenuates Diabetic Nephropathy by Promoting ABCA1-Mediated Renal Cholesterol Efflux in db/db Mice.

    Science.gov (United States)

    Liu, Peng; Peng, Liang; Zhang, Haojun; Tang, Patrick Ming-Kuen; Zhao, Tingting; Yan, Meihua; Zhao, Hailing; Huang, Xiaoru; Lan, Huiyao; Li, Ping

    2018-01-01

    The commonly prescribed Tangshen Formula (TSF) is a traditional Chinese formulation that has been shown to reduce plasma lipid metabolism and proteinuria and improve the estimated glomerular filtration rate (eGFR) in patients with diabetic kidney disease. This study investigated the underlying mechanism whereby TSF regulates renal lipid accumulation and ameliorates diabetic renal injuries in spontaneous diabetic db/db mice and in vitro in sodium palmitate (PA)-stimulated and Abca1-SiRNA-transfected mouse tubular epithelial cells (mTECs). The results revealed that TSF treatment significantly ameliorated the renal injuries by lowering urinary albumin excretion and improving renal tissue injuries in diabetic (db/db) mice. Interestingly, the treatment with TSF also resulted in decreased cholesterol levels in the renal tissues of db/db mice, which was associated with increased expression of the peroxisome proliferator-activated receptor γ coactivator 1-α (PGC-1α), the Liver X receptors (LXR), and ATP-binding cassette subfamily A member 1 (ABCA1), suggesting that TSF might attenuate diabetic kidney injury via a mechanism associated with improving cholesterol efflux in the diabetic kidney. This was investigated in vitro in mTECs, and the results showed that TSF reduced the PA-stimulated cholesterol accumulation in mTECs. Mechanistically, the addition of TSF was capable of reversing PA-induced downregulation of PGC-1α, LXR, and ABCA1 expression and cholesterol accumulation in mTECs, suggesting that TSF might act the protection via the PGC-1α-LXR-ABCA1 pathway to improve the cholesterol efflux in the renal tissues of db/db mice. This was further confirmed by silencing ABCA1 to block the promotive effect of TSF on cholesterol efflux in vitro . In conclusion, TSF might ameliorate diabetic kidney injuries by promoting ABCA1-mediated renal cholesterol efflux.

  9. A mass spectrometry-based assay for improved quantitative measurements of efflux pump inhibition.

    Directory of Open Access Journals (Sweden)

    Adam R Brown

    Full Text Available Bacterial efflux pumps are active transport proteins responsible for resistance to selected biocides and antibiotics. It has been shown that production of efflux pumps is up-regulated in a number of highly pathogenic bacteria, including methicillin resistant Staphylococcus aureus. Thus, the identification of new bacterial efflux pump inhibitors is a topic of great interest. Existing assays to evaluate efflux pump inhibitory activity rely on fluorescence by an efflux pump substrate. Wh