The Experts below are selected from a list of 15453 Experts worldwide ranked by ideXlab platform
Jeanlouis Drouet - One of the best experts on this subject based on the ideXlab platform.
-
changes in spatial patterns of ammonia dry deposition flux and deposition threshold Exceedance according to dispersion model formalism and horizontal resolution
Environmental Pollution, 2021Co-Authors: Niramson Azouz, Matthias Beekmann, Guillaume Siour, Pierre Cellier, Jeanlouis DrouetAbstract:Abstract Ammonia (NH3) emitted into the atmosphere from agricultural sources may affect nearby sensitive ecosystems due to high dry deposition fluxes on vegetation and soil surfaces, contributing to critical load Exceedances. Ammonia fluxes near sources are simulated by either short-range atmospheric models or regional models using large grid cell sizes. However, studies are missing on the comparison of the results simulated by these two types of models. This paper presents the effect of model formalism, input factors, especially grid cell size and wind speed and the choice of deposition threshold on the spatial patterns of NH3 dry deposition fluxes and deposition threshold Exceedances. We used the Eulerian chemistry-transport model CHIMERE and the Gaussian plume model OPS-ST on two study domains characterised by contrasting land use. We showed that the average annual NH3 dry deposition fluxes over each whole domain are similar for both models. By contrast, NH3 dry deposition fluxes near sources are higher when simulated with OPS-ST that provides analytical solutions that can be sampled with small grid cell sizes (i.e., from 25 to 1600 m in this study), than with CHIMERE, which uses large grid cell sizes (i.e., 800 and 1600 m). As a result, the spatial patterns of deposition threshold Exceedance were very different between both models. These patterns depend mainly on grid cell size, the input factors and the choice of the deposition threshold value. We show that the model formalism has a relatively small effect on the results and that the differences result mainly from the spatial resolutions to which they can be applied. Simulation results must therefore be interpreted carefully, taking into account the simulation conditions.
M A Sutton - One of the best experts on this subject based on the ideXlab platform.
-
the influence of model grid resolution on estimation of national scale nitrogen deposition and Exceedance of critical loads
Biogeosciences, 2012Co-Authors: Anthony J Dore, Maciej Kryza, Jane Hall, Stephen Hallsworth, V J D Keller, Massimo Vieno, M A SuttonAbstract:Abstract. The Fine Resolution Atmospheric Multi-pollutant Exchange model (FRAME) was applied to model the spatial distribution of reactive nitrogen deposition and air concentration over the United Kingdom at a 1 km spatial resolution. The modelled deposition and concentration data were gridded at resolutions of 1 km, 5 km and 50 km to test the sensitivity of calculations of the Exceedance of critical loads for nitrogen deposition to the deposition data resolution. The modelled concentrations of NO2 were validated by comparison with measurements from the rural sites in the national monitoring network and were found to achieve better agreement with the high resolution 1 km data. High resolution plots were found to represent a more physically realistic distribution of reactive nitrogen air concentrations and deposition resulting from use of 1 km resolution precipitation and emissions data as compared to 5 km resolution data. Summary statistics for national scale Exceedance of the critical load for nitrogen deposition were not highly sensitive to the grid resolution of the deposition data but did show greater area Exceedance with coarser grid resolution due to spatial averaging of high nitrogen deposition hot spots. Local scale deposition at individual Sites of Special Scientific Interest and high precipitation upland sites was sensitive to choice of grid resolution of deposition data. Use of high resolution data tended to generate lower deposition values in sink areas for nitrogen dry deposition (Sites of Scientific Interest) and higher values in high precipitation upland areas. In areas with generally low Exceedance (Scotland) and for certain vegetation types (montane), the Exceedance statistics were more sensitive to model data resolution.
Barbara Wolff - One of the best experts on this subject based on the ideXlab platform.
-
Exceedance of critical loads of nitrogen and sulphur and its relation to forest conditions
European Journal of Forest Research, 2005Co-Authors: Sabine Augustin, Andreas Bolte, Marieanna Holzhausen, Barbara WolffAbstract:The calculation of critical loads and their Exceedance is one method to describe the vulnerability of forests to environmental stress caused by anthropogenic impact. Exceedance of critical loads for acidifying inputs and nitrogen was compared to different indicators of the soil and forest conditions in the German part of the extensive forest monitoring (ICP Forests/EU Level I), including more than 1,800 plots. In addition, an empirical relationship between the C/N ratio of the forest floor humus layer ( C/N _Humus) and the estimated nitrogen output for ten plots of the intensive monitoring (ICP Forests/EU Level II) was established in order to estimate the potential nitrogen output on Level I plots dominated by Norway spruce. Regarding all tree species assessed, the Exceedance of critical loads for nitrogen and sulphur is negatively correlated with pH and base saturation up to 30 cm soil depth. The sulphur deposition and the Exceedance of critical loads are highly correlated with the sulphur content of leaves and needles, whereas the respective relations for nitrogen were lower. The crown condition was weakly positively related to the sulphur content in tree leaves and needles. For Norway spruce sites, high Exceedance of critical loads for nitrogen and nitrogen deposition corresponded well with low C/N _Humus. In regions with high nitrogen load and low C/N ratios in the humus layer, the calculated nitrogen output was high. The results support the concept of critical thresholds in that way that their Exceedance can impair forest ecosystem functions like nitrogen retention.
L. H. Pardo - One of the best experts on this subject based on the ideXlab platform.
-
present and future nitrogen deposition to national parks in the united states critical load Exceedances
Atmospheric Chemistry and Physics, 2013Co-Authors: R A Ellis, Daniel J Jacob, Melissa P Sulprizio, Lin Zhang, Christopher D Holmes, Bret A Schichtel, Tamara Blett, Ellen Porter, L. H. PardoAbstract:Abstract. National parks in the United States are protected areas wherein the natural habitat is to be conserved for future generations. Deposition of anthropogenic nitrogen (N) transported from areas of human activity (fuel combustion, agriculture) may affect these natural habitats if it exceeds an ecosystem-dependent critical load (CL). We quantify and interpret the deposition to Class I US national parks for present-day and future (2050) conditions using the GEOS-Chem global chemical transport model with 1/2° × 2/3° horizontal resolution over North America. We estimate CL values in the range 2.5–5 kg N ha−1 yr−1 for the different parks to protect the most sensitive ecosystem receptors. For present-day conditions, we find 24 out of 45 parks to be in CL Exceedance and 14 more to be marginally so. Many of these are in remote areas of the West. Most (40–85%) of the deposition originates from NOx emissions (fuel combustion). We project future changes in N deposition using representative concentration pathway (RCP) anthropogenic emission scenarios for 2050. These feature 52–73% declines in US NOx emissions relative to present but 19–50% increases in US ammonia (NH3) emissions. Nitrogen deposition at US national parks then becomes dominated by domestic NH3 emissions. While deposition decreases in the East relative to present, there is little progress in the West and increases in some regions. We find that 17–25 US national parks will have CL Exceedances in 2050 based on the RCP8.5 and RCP2.6 scenarios. Even in total absence of anthropogenic NOx emissions, 14–18 parks would still have a CL Exceedance. Returning all parks to N deposition below CL by 2050 would require at least a 50% decrease in US anthropogenic NH3 emissions relative to RCP-projected 2050 levels.
-
Susceptibility of Forests in the Northeastern USA to Nitrogen and Sulfur Deposition: Critical Load Exceedance and Forest Health
Water Air & Soil Pollution, 2013Co-Authors: N Duarte, L. H. Pardo, M. J. Robin-abbottAbstract:The objectives of this study were to assess susceptibility to acidification and nitrogen (N) saturation caused by atmospheric deposition to northeastern US forests, evaluate the benefits and shortcomings of making critical load assessments using regional data, and assess the relationship between expected risk (Exceedance) and forest health. We calculated the critical loads of nutrient N and of sulfur (S) + N using the steady-state mass balance method at >4,000 regional and national vegetation and soil monitoring network plots in the northeastern USA. Regional calculations of critical loads necessitate use of soil maps which provide a range for each soil characteristic resulting in a broad range of critical load of S + N and Exceedance values. For the scenario most representative of regional conditions, over 80 % of the critical loads fell into the range of 850–2050 eq ha^−1 yr^−1; at 45 % of the plots, deposition exceeded the critical load. In contrast, the critical load for nutrient N, 200–300 eq ha^−1 yr^−1, was lower. Site measurements, especially to estimate soil weathering, would increase the certainty of the critical load. We observed significant negative correlations between critical load Exceedance and growth (17 species) and crown density (4 species); we observed significant positive correlations of Exceedance with declining vigor (four species), with crown dieback (six species) and crown transparency (seven species). Among the species which demonstrate the most significant detrimental responses to atmospheric deposition are balsam fir, red spruce, quaking aspen, and paper birch. These results indicate that significant detrimental responses to atmospheric deposition are being observed across the northeastern USA.
Claudio Jose Struchiner - One of the best experts on this subject based on the ideXlab platform.
-
risk of the brazilian health care system over 5572 municipalities to exceed health care capacity due to the 2019 novel coronavirus covid 19
Science of The Total Environment, 2020Co-Authors: Weeberb J Requia, Edson Kenji Kondo, Matthew D Adams, Diane R Gold, Claudio Jose StruchinerAbstract:The spread of the 2019 novel coronavirus (COVID-19) has challenged governments to develop public policies to reduce the load of the COVID-19 on health care systems, which is commonly referred to as "flattening the curve". This study aims to address this issue by proposing a spatial multicriteria approach to estimate the risk of the Brazilian health care system, by municipality, to exceed the health care capacity because of an influx of patients infected with the COVID-19. We estimated this risk for 5572 municipalities in Brazil using a combination of a multicriteria decision-making approach with spatial analysis to estimate the Exceedance risk, and then, we examined the risk variation by designing 5 control intervention scenarios (3 scenarios representing reduction on social contacts, and 2 scenarios representing investment on health care system). For the baseline scenario using an average infection rate across Brazil, we estimated a mean Hospital Bed Capacity (HBC) value of -16.73, indicating that, on average, the Brazilian municipalities will have a deficit of approximately 17 beds. This deficit is projected to occur in 3338 municipalities with the north and northeast regions being at the greatest risk of exceeding health care capacity due to the COVID-19. The intervention scenarios indicate across all of Brazil that they could address the bed shortage, with an average of available beds between 23 and 32. However, when we consider the shortages at a municipal scale, bed Exceedances still occur for at least 2119 municipalities in the most effective intervention scenario. Our findings are essential to identify priority areas, to compare populations, and to provide options for government agencies to act. This study can be used to provide support for the creation of effective health public policies for national, regional, and local intervention.
