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1.
Chapter three: methodology of exposure modeling 总被引:1,自引:0,他引:1
Moschandreas DJ Watson J D'Abreton P Scire J Zhu T Klein W Saksena S 《Chemosphere》2002,49(9):923-946
In this chapter, the concept of exposure assessment and its evolution is introduced, and evaluated by critically appraising the pertinent literature as it applies to exposures to Particulate Matter (PM). Exposure measurement or estimation methodologies and models are reviewed. Three exposure/measurement methodologies are assessed. Estimation methods focus on source evaluation and attribution, sources include those outdoors and indoors as well as in occupational and in-transit environments. Fate and transport models and their inputs are addressed to estimate concentrations outdoors and indoors; source attribution techniques help focus on the contributing sources. Activity pattern techniques are also reviewed and their use in exposure models to estimate inhalation exposure to PM is presented. Deterministic, regression and other stochastic models of exposure to PM are reviewed and evaluated. Strengths, limitations, assumptions and affirmations of the use of exposure assessment as an integral component of risk assessment and risk management are discussed in the conclusions and discussions section of this work. 相似文献
2.
《Atmospheric environment (Oxford, England : 1994)》2007,41(34):7151-7165
The atmosphere is an important transient reservoir of selenium (Se). According to recent evaluations of the global Se budget, approximately 13,000–19,000 tons of Se is cycled through the troposphere annually. Most studies suggest that atmospheric deposition is an important source of Se contamination and it is therefore critical to evaluate the source emissions and fate of Se in the atmosphere. This paper presents a broad overview of current state of knowledge and understanding of major aspects of atmospheric Se and its natural and anthropogenic sources. The significant physical and chemical species encountered in the atmosphere are examined and special attention is paid to atmospheric speciation and its atmospheric pathways and processes. In addition, thermodynamic and kinetic data for atmospheric Se speciation are provided, which aid our understanding and the modelling of Se behaviour in the atmospheric environment. We also document how Se isotopes might be useful for tracing atmospheric sources and pathways. Important gaps in our current knowledge of Se in the atmospheric environment are identified, and suggestions for future research are offered. 相似文献
3.
Patricia Brewer Gail Tonnesen Ralph Morris Tom Moore Uarporn Nopmongcol Debra Miller 《Journal of the Air & Waste Management Association (1995)》2019,69(3):373-390
The 2017 revisions to the Regional Haze Rule clarify that visibility progress at Class I national parks and wilderness areas should be tracked on days with the highest anthropogenic contributions to haze (impairment). We compare the natural and anthropogenic contributions to haze in the western United States in 2011 estimated using the Environmental Protection Agency (EPA) recommended method and using model projections from the Comprehensive Air Quality Model with Extensions (CAMx) and the Particulate Source Apportionment Tool (PSAT). We do so because these two methods will be used by states to demonstrate visibility progress by 2028. If the two methods assume different natural and anthropogenic contributions, the projected benefits of reducing U.S. anthropogenic emissions will differ. The EPA method assumes that episodic elevated carbonaceous aerosols greater than an annual 95th percentile threshold are natural events. For western U.S. IMPROVE monitoring sites reviewed in this paper, CAMx-PSAT confirms these episodes are impacted by carbon from wildfire or prescribed fire events. The EPA method assumes that most of the ammonium sulfate is anthropogenic in origin. At most western sites CAMx-PSAT apportions more of the ammonium sulfate on the most impaired days to global boundary conditions and anthropogenic Canadian, Mexican, and offshore shipping emissions than to U.S. anthropogenic sources. For ammonium nitrate and coarse mass, CAMx-PSAT apportions greater contributions to U.S. anthropogenic sources than the EPA method assigns to total anthropogenic contributions. We conclude that for western IMPROVE sites, the EPA method is effective in selecting days that are likely to be impacted by anthropogenic emissions and that CAMx-PSAT is an effective approach to estimate U.S. source contributions. Improved inventories, particularly international and natural emissions, and further evaluation of global and regional model performance and PSAT attribution methods are recommended to increase confidence in modeled source characterization.
Implications: The western states intend to use the CAMx model to project visibility progress by 2028. Modeled visibility response to changes in U.S. anthropogenic emissions may be less than estimated using the EPA assumptions based on total U.S. and international anthropogenic contributions to visibility impairment. Additional model improvements are needed to better account for contributions to haze from natural and international emissions in current and future modeling years. These improvements will allow more direct comparison of model and EPA estimates of natural and anthropogenic contributions to haze and future visibility progress. 相似文献
4.
Meiyun Lin Taikan Oki Magnus Bengtsson Shinjiro Kanae Tracey Holloway David G. Streets 《Atmospheric environment (Oxford, England : 1994)》2008,42(24):5956-5967
Region-to-grid source–receptor (S/R) relationships are established for sulfur and reactive nitrogen deposition in East Asia, using the Eulerian-type Community Multiscale Air Quality (CMAQ) model with emission and meteorology data for 2001. We proposed a source region attribution methodology by analyzing the non-linear responses of the CMAQ model to emission changes. Sensitivity simulations were conducted where emissions of SO2, NOx, and primary particles from a source region were reduced by 25%. The difference between the base and sensitivity simulations was multiplied by a factor of four, and then defined as the contribution from that source region. The transboundary influence exhibits strong seasonal variation and generally peaks during the dry seasons. Long-range transport from eastern China contributes a significant percentage (>20%) of anthropogenic reactive nitrogen as well as sulfur deposition in East Asia. At the same time, northwestern China receives approximately 35% of its sulfur load and 45% of its nitrogen load from foreign emissions. Sulfur emissions from Miyakejima and other volcanoes contribute approximately 50% of the sulfur load in Japan in 2001. Sulfur inflows from regions outside the study domain, which is attributed by using boundary conditions derived from the MOZART global atmospheric chemistry model, are pronounced (10–40%) over most parts of Asia. Compared with previous studies using simple Lagrangian models, our results indicate higher influence from long-range transport. The estimated S/R relationships are believed to be more realistic since they include global influence as well as internal interactions among different parts of China. 相似文献
5.
Lin CJ Shetty SK Pan L Pongprueksa P Jang C Chu HW 《Journal of the Air & Waste Management Association (1995)》2012,62(1):52-63
Quantifying the contribution of emission sources responsible for mercury deposition in specific receptor regions helps develop emission control strategies that alleviate the impact on ecosystem and human health. In light of the maximum available control technology (MACT) rules proposed by U.S. Environmental Protection Agency (EPA) and the ongoing intergovernmental negotiation coordinated by United Nations Environmental Programme (UNEP) for mercury, the Community Multiscale Air Quality Modeling System (CMAQ-Hg) was applied to estimate the source contribution in six subregions of the contiguous United States (CONUS). The considered source categories include electric generating units (EGU), iron and steel industry (IRST), other industrial point sources excluding EGU and IRST (OIPM), the remaining anthropogenic sources (RA), natural processes (NAT), and out-of-boundary transport (BC). It is found that, on an annual basis, dry deposition accounts for two-thirds of total annual deposition in CONUS (474 Mg yr(-1)), mainly contributed by reactive gaseous mercury (about 60% of total deposition). The contribution from large point sources can be as high as 75% near the emission sources (< 100 km), indicating that emission reduction may result in direct deposition decrease near the source locations. Out-of-boundary transport contributes from 68% (Northeast) to 91% (West Central) of total deposition. Excluding the contribution from out-of boundary transport, EGU contributes to about 50% of deposition in the Northeast, Southeast, and East Central regions, whereas emissions from natural processes are more important in the Pacific and West Central regions (contributing up to 40% of deposition). This suggests that the implementation of the new EPA MACT standards will significantly benefit only these three regions. Emission speciation is a key factor for local deposition. The source contribution exhibits strong seasonal variation. Deposition is greater in warm seasons due to stronger Hg0 oxidation. However, the contribution from anthropogenic sources is smaller in warm seasons because of larger emissions from natural processes and stronger vertical mixing that facilitates transport. 相似文献
6.
Wilson LJ Bacon PJ Bull J Dragosits U Blackall TD Dunn TE Hamer KC Sutton MA Wanless S 《Environmental pollution (Barking, Essex : 1987)》2004,131(2):173-185
Knowledge of the sources and distribution of ammonia (NH3) emissions underpins our understanding of the nitrogen budget. Research has focused on quantifying NH3 emissions from anthropogenic sources, whilst those from natural sources have received little attention internationally. Seabirds excrete large quantities of nitrogen, making seabird colonies a major natural source of NH3. Ammonia emissions from each UK seabird species were estimated and combined with population distribution data to model their spatial distribution. Total NH3 emissions from UK seabirds were estimated at 2.7 kt per year. Seabird emissions are concentrated in remote parts of the UK where anthropogenic emissions are small, so that seabirds often represent the main source of NH3 emissions in these areas. Seabird NH3 emissions were found to have increased by 34% since the 1970s. This corresponds to population changes which may be influenced by human activities, showing that even this natural source can be anthropogenically modified. 相似文献
7.
《Atmospheric environment(England)》1985,19(9):1439-1443
The sulfur budget for Colorado is analyzed in order to understand the importance of interstate transport and natural sources to wet sulfur deposition in the state. A climatological box model is used to separate the various contributions to sulfur deposition. We demonstrate that sulfur dioxide molecules emitted in Colorado have a low probability of wet deposition in Colorado. Therefore, as much as 80 per cent or more of the wet sulfur deposition in the state must be ascribed to external anthropogenic sulfur sources, such as non-ferrous metal smelters and electric powerplants unless some large unspecified natural sulfur source exists. 相似文献
8.
Seigneur C Lohman K Vijayaraghavan K Shia RL 《Environmental pollution (Barking, Essex : 1987)》2003,123(3):365-373
A modeling system that includes a global chemical transport model (CTM) and a nested continental CTM (TEAM) was used to simulate the atmospheric transport, transformations and deposition of mercury (Hg). Three scenarios were used: (1) a nominal scenario, (2) a scenario conducive to local deposition and (3) a scenario conducive to long-range transport. Deposition fluxes of Hg were analyzed at three receptor locations in New York State. For the nominal scenario, the anthropogenic emission sources (including re-emission of deposited Hg) in New York State, the rest of the contiguous United States, Asia, Europe, and Canada contributed 11-1, 25-9, 13-19, 5-7, and 2-5%, respectively to total Hg deposition at these three receptors. Natural sources contributed 16-4%. The results from the local deposition and long-range transport scenarios varied only slightly from these results. However, there are still uncertainties in our understanding of the atmospheric chemistry of Hg that are likely to affect these estimates of local, regional and global contributions. Comparison of model simulation results with data from the Mercury Deposition Network suggests that local and regional contributions may currently be overestimated. 相似文献
9.
Sunderland EM Cohen MD Selin NE Chmura GL 《Environmental pollution (Barking, Essex : 1987)》2008,156(2):526-535
Changes in atmospheric mercury deposition are used to evaluate the effectiveness of regulations controlling emissions. This analysis can be complicated by seemingly incongruent data from different model runs, model types, and field measurements. Here we present a case study example that describes how to identify trends in regional scale mercury deposition using best-available information from multiple data sources. To do this, we use data from three atmospheric chemistry models (CMAQ, GEOS-Chem, HYSPLIT) and multiple sediment archives (ombrotrophic bog, headwater lake, coastal salt marsh) from the Bay of Fundy region in Canada. Combined sediment and modeling data indicate that deposition attributable to US and Canadian emissions has declined in recent years, thereby increasing the relative significance of global sources. We estimate that anthropogenic emissions in the US and Canada account for 28-33% of contemporary atmospheric deposition in this region, with the rest from natural (14-32%) and global sources (41-53%). 相似文献
10.
《Atmospheric environment(England)》1978,12(1-3):489-501
A model based on statistical distributions of windspeed, wind direction and dispersion categories and of rainfall is used to calculate the annual wet and dry deposition of sulphur over Europe, using a detailed emission inventory. The model explicitly allows for vertical diffusion in the mixing layer and thereby the effect of source height. Wet and dry removal are taken into account as well as the conversion of sulphur dioxide to sulphate. In regions of Europe with heavy annual precipitation, such as southwest Norway, corrections to the deposition pattern are made.Other factors, such as the diurnal variation of mixing depth and large scale synoptic vertical motions, are investigated and are not thought to change the overall pattern of annual deposition. The calculated pattern compares favourably with measurements and calculations based on trajectory models. The results show that the highest total deposition rates occur over the major emission areas (10g m−2 y−1 SO2)and decrease to low values (1 gm−2 y−1 SO2) in outlying areas of the U.K., France, Italy and in Scandinavia. The wet deposition does not show such pronounced maxima close to emissions. The decrease in wet deposition is also modified in regions of heavy annual precipitation, such as southern Norway.A sulphur budget is constructed for a region of southern Norway. The calculated total deposition, which agrees fairly well with the measured total deposition, is analysed according to the sectors containing the main source areas. The contribution from each source sector is only estimated approximately (to within a factor of two) but shows the expected dependence on source strength and frequency of wind direction. The main uncertainty is a large contribution from the background concentration of sulphate in precipitation not directly attributable to man-made sources in Europe.The model calculation excludes the contribution from sources within about 100 km of a receptor site. The deposition at any sampling site is dependent on details of the source emissions within the neighbourhood of the site. However the average regional deposition from sources within the receptor region can be assessed. It is small for southern Norway because of the low emissions in the region. Source height strongly influences the local deposition, but on a larger scale is less important than other factors, such as the frequency of wind direction, rainfall and uncertainties in the emission inventory. 相似文献
11.
Brimblecombe P 《Environmental pollution (Barking, Essex : 1987)》1994,83(1-2):81-85
The rate of deposition of elements at a point on the earth's surface can change, quite dramatically, even on relatively short time-scales, as a function of weather patterns. On a global scale volcanoes (and more rarely large meteors) can overwhelm steadier sources of trace elements. In recent centuries human activities have increased emissions to the atmosphere to a point where they are above those of natural sources for some of the rarer elements. On a longer time-scale climate change can also alter the deposition of elements, although such changes are often slower than those brought about through anthropogenic emissions. Changes in climate can also alter the distribution of deposition, but there are few studies estimating such changes. This paper uses estimates of the balance of natural and anthropogenic sources of a range of elements to examine the likely variation in deposition at the earth's surface. It particularly focuses on those elements regarded as toxic, whose concentrations seem likely to go on increasing in industrial areas. 相似文献
12.
《Atmospheric environment (Oxford, England : 1994)》2007,41(6):1135-1149
Most studies on the atmospheric behaviour of mercury in North America have excluded a detailed treatment of natural mercury emissions. The objective of this work is to report a detailed simulation of the atmospheric mercury in a domain that covers a significant part of North America and includes not only anthropogenic mercury emissions but also those from natural sources including vegetation, soil and water.The simulations were done using a natural mercury emission model coupled with the US EPA's SMOKE/CMAQ modelling system. The domain contained 132×90 grid cells at a resolution of 36 km, covering the continental United States, and major parts of Canada and Mexico. The simulation was carried out for 2002, using boundary conditions from a global mercury model. Estimated total natural mercury emission in the domain was 230 tonnes (1 tonne=1000 kg) and the ratio of natural to anthropogenic emissions varied from 0.7 in January to 3.2 in July. Average total gaseous mercury (TGM) concentration ranged between 1 and 4 ng m−3. Good agreement was found between the modelled results and measurements at three Ontario sites for ambient mercury concentrations, and at 72 mercury deposition network sites in the domain for wet deposition. The correlation coefficient between the simulated and the measured values of the daily average TGM at three monitoring sites varied between 0.48 and 0.64. When natural emissions were omitted, the correlation coefficients dropped to between 0.15 and 0.40. About 335 tonnes of mercury were deposited in the domain during the simulation period but overall, it acted as a net source of mercury and contributed about 21 tonnes to the global pool. The net deposition of mercury to the Great Lakes was estimated to be about 2.4 tonnes. The estimated deposition values were similar to those reported by other researchers. 相似文献
13.
The sources and distribution of anthropogenic nitrogen (N), including N fertilization and N fixed during fossil-fuel combustion, are rapidly becoming globally distributed. Responses of terrestrial ecosystems to anthropogenic N inputs are likely to vary geographically. In the temperate zone, long-term N inputs can lead to increases in plant growth and also can result in over-enrichment with N, eventually leading to increased losses of N via solution leaching and trace-gas emissions, and in some cases, to changes in species composition and to ecosystem decline. However, not all ecosystems respond to N deposition similarly; their response depends on factors such as successional state, ecosystem type, N demand or retention capacity, land-use history, soils, topography, climate, and the rate, timing, and type of N deposition. We point to some of the conditions under which anthropogenic impacts can be significant, some of the factors that control variations in response, and some areas where uncertainty is large due to limited information. 相似文献
14.
Ammonia in the atmosphere: a review on emission sources, atmospheric chemistry and deposition on terrestrial bodies 总被引:10,自引:0,他引:10
Sailesh N. Behera Mukesh Sharma Viney P. Aneja Rajasekhar Balasubramanian 《Environmental science and pollution research international》2013,20(11):8092-8131
Gaseous ammonia (NH3) is the most abundant alkaline gas in the atmosphere. In addition, it is a major component of total reactive nitrogen. The largest source of NH3 emissions is agriculture, including animal husbandry and NH3-based fertilizer applications. Other sources of NH3 include industrial processes, vehicular emissions and volatilization from soils and oceans. Recent studies have indicated that NH3 emissions have been increasing over the last few decades on a global scale. This is a concern because NH3 plays a significant role in the formation of atmospheric particulate matter, visibility degradation and atmospheric deposition of nitrogen to sensitive ecosystems. Thus, the increase in NH3 emissions negatively influences environmental and public health as well as climate change. For these reasons, it is important to have a clear understanding of the sources, deposition and atmospheric behaviour of NH3. Over the last two decades, a number of research papers have addressed pertinent issues related to NH3 emissions into the atmosphere at global, regional and local scales. This review article integrates the knowledge available on atmospheric NH3 from the literature in a systematic manner, describes the environmental implications of unabated NH3 emissions and provides a scientific basis for developing effective control strategies for NH3. 相似文献
15.
《Atmospheric environment (Oxford, England : 1994)》2007,41(38):8557-8566
Current atmospheric emissions of As, Cd, Cr, Ni, and Pb (reference year 2000) from major anthropogenic sources in Europe are presented in this paper. Combustion of fuels in stationary sources was the main emission source for As, Cd, Cr, and Ni (more than a half of the total anthropogenic emissions), while combustion of gasoline was the main source of for lead. There is a continuous reduction of heavy metal emissions in Europe during the last 40 years. Better knowledge of heavy metal sources, emissions, pathways, and fate in the environment, and progress in developing efficient emission control equipment has resulted in more efficient regulatory efforts to curb heavy metal emissions from anthropogenic sources very substantially. There is a potential for further reduction of these emissions until the year 2010 up to about 40% for As, Cd, Cr, and Ni and about 57% for Pb, as estimated within various emission scenarios presented in the paper. 相似文献
16.
A robust approach for iterative contaminant source location and release history recovery 总被引:1,自引:0,他引:1
Contamination source identification is a crucial step in environmental remediation. The exact contaminant source locations and release histories are often unknown due to lack of records and therefore must be identified through inversion. Coupled source location and release history identification is a complex nonlinear optimization problem. Existing strategies for contaminant source identification have important practical limitations. In many studies, analytical solutions for point sources are used; the problem is often formulated and solved via nonlinear optimization; and model uncertainty is seldom considered. In practice, model uncertainty can be significant because of the uncertainty in model structure and parameters, and the error in numerical solutions. An inaccurate model can lead to erroneous inversion of contaminant sources. In this work, a constrained robust least squares (CRLS) estimator is combined with a branch-and-bound global optimization solver for iteratively identifying source release histories and source locations. CRLS is used for source release history recovery and the global optimization solver is used for location search. CRLS is a robust estimator that was developed to incorporate directly a modeler's prior knowledge of model uncertainty and measurement error. The robustness of CRLS is essential for systems that are ill-conditioned. Because of this decoupling, the total solution time can be reduced significantly. Our numerical experiments show that the combination of CRLS with the global optimization solver achieved better performance than the combination of a non-robust estimator, i.e., the nonnegative least squares (NNLS) method, with the same solver. 相似文献
17.
《Journal of contaminant hydrology》2007,89(3-4):181-196
Contamination source identification is a crucial step in environmental remediation. The exact contaminant source locations and release histories are often unknown due to lack of records and therefore must be identified through inversion. Coupled source location and release history identification is a complex nonlinear optimization problem. Existing strategies for contaminant source identification have important practical limitations. In many studies, analytical solutions for point sources are used; the problem is often formulated and solved via nonlinear optimization; and model uncertainty is seldom considered. In practice, model uncertainty can be significant because of the uncertainty in model structure and parameters, and the error in numerical solutions. An inaccurate model can lead to erroneous inversion of contaminant sources. In this work, a constrained robust least squares (CRLS) estimator is combined with a branch-and-bound global optimization solver for iteratively identifying source release histories and source locations. CRLS is used for source release history recovery and the global optimization solver is used for location search. CRLS is a robust estimator that was developed to incorporate directly a modeler's prior knowledge of model uncertainty and measurement error. The robustness of CRLS is essential for systems that are ill-conditioned. Because of this decoupling, the total solution time can be reduced significantly. Our numerical experiments show that the combination of CRLS with the global optimization solver achieved better performance than the combination of a non-robust estimator, i.e., the nonnegative least squares (NNLS) method, with the same solver. 相似文献
18.
《Atmospheric environment(England)》1979,13(4):465-476
Mercury deposition — dry and wet — and re-emission from the ground has been studied around two chlor-alkali plants in Sweden. The experimental data are:
- 1.(1) monthly precipitation samples up to ca. 35km from the sources;
- 2.(2) air samples from 14 tests of 45 min duration each taken at 15–20 sites up to 5 km distance from the source;
- 3.(3) emission data from the tests mentioned above under (2).
19.
《Atmospheric environment (Oxford, England : 1994)》2007,41(35):7414-7433
This paper presents chemical mass balance (CMB) analysis of organic molecular marker data to investigate the sources of organic aerosol and PM2.5 mass in Pittsburgh, Pennsylvania. The model accounts for emissions from eight primary source classes, including major anthropogenic sources such as motor vehicles, cooking, and biomass combustion as well as some primary biogenic emissions (leaf abrasion products). We consider uncertainty associated with selection of source profiles, selection of fitting species, sampling artifacts, photochemical aging, and unknown sources. In the context of the overall organic carbon (OC) mass balance, the contributions of diesel, wood-smoke, vegetative detritus, road dust, and coke-oven emissions are all small and well constrained; however, estimates for the contributions of gasoline-vehicle and cooking emissions can vary by an order of magnitude. A best-estimate solution is presented that represents the vast majority of our CMB results; it indicates that primary OC only contributes 27±8% and 50±14% (average±standard deviation of daily estimates) of the ambient OC in the summer and winter, respectively. Approximately two-thirds of the primary OC is transported into Pittsburgh as part of the regional air mass. The ambient OC that is not apportioned by the CMB model is well correlated with secondary organic aerosol (SOA) estimates based on the EC-tracer method and ambient concentrations of organic species associated with SOA. Therefore, SOA appears to be the major component of OC, not only in summer, but potentially in all seasons. Primary OC dominates the OC mass balance on a small number of nonsummer days with high OC concentrations; these events are associated with specific meteorological conditions such as local inversions. Primary particulate emissions only contribute a small fraction of the ambient fine-particle mass, especially in the summer. 相似文献
20.
Fabian P Kohlpaintner M Rollenbeck R 《Environmental science and pollution research international》2005,12(5):290-296
Background Biomass burning is a source of carbon, sulfur and nitrogen compounds which, along with their photochemically generated reaction
products, can be transported over very long distances, even traversing oceans. Chemical analyses of rain and fogwater samples
collected in the mountaineous rain forest of south Ecuador show frequent episodes of high sulfate and nitrate concentration,
from which annual deposition rates are derived comparable to those found in polluted central Europe. As significant anthropogenic
sources are lacking at the research site it is suspected that biomass burning upwind in the Amazon basin is the major source
of the enhanced sulfate and nitrate imput.
Methods Regular rain and fogwater sampling along an altitude profile between 1800 and 3185 m has been carried out in the Podocarpus
National Park close to the Rio SanFrancisco (3°58'S, 79°5'W) in southern Ecuador. pH values, electrical conductivity and chemical
ion composition were measured at the TUM-WZW using standard methods.
Results and Discussion Results reported cover over one year from March 2002 until May 2003. Annual deposition rates of sulfate were calculated ranging
between 4 and 13 kg S/ha year, almost as high as in polluted central Europe. Nitrogen deposition via ammonia (1.5–4.4 kg N/ha
year) and nitrate (0.5–0.8 kg N/ha year) was found to be lower but still much higher than to be expected in such pristine
natural forest environment. By means of back trajectory analyses it can be shown that most of the enhanced sulfur and nitrogen
deposition is most likely due to forest fires far upwind of the Ecuadorian sampling site, showing a seasonal variation, with
sources predominantly found in the East/NorthEast during January–March (Colombia, Venezuela, Northern Brazil) and East/SouthEast
during July–September (Peru, Brazil).
Conclusion Our results show that biomass burning in the Amazon basin is the predominant source of sulfur and nitrogen compounds that
fertilize the mountaineous rain forest in south Ecuador.
Recommendation and Outlook The mountaineous rain forest in south Ecuador has developed on poor and acid soils, with low nutrient availability. The additional
fertilization resulting from anthropogenic biomass burning constitutes a significant disturbance of this ecosystem, its functioning
and biodiversity. Thus it is planned to employ isotope analyses for quantifying the pathways of nitrate and sulfate deposition
in these natural forests. 相似文献