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Sample records for atmospheric hg deposition

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

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    Feng X.

    2013-04-01

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

  2. Atmospheric mercury deposition to forests in the eastern USA

    International Nuclear Information System (INIS)

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

    2017-01-01

    Atmospheric mercury (Hg) deposition to forests is important because half of the land cover in the eastern USA is forest. Mercury was measured in autumn litterfall and weekly precipitation samples at a total of 27 National Atmospheric Deposition Program (NADP) monitoring sites in deciduous and mixed deciduous-coniferous forests in 16 states in the eastern USA during 2007–2014. These simultaneous, uniform, repeated, annual measurements of forest Hg include the broadest area and longest time frame to date. The autumn litterfall-Hg concentrations and litterfall mass at the study sites each year were combined with annual precipitation-Hg data. Rates of litterfall-Hg deposition were higher than or equal to precipitation-Hg deposition rates in 70% of the annual data, which indicates a substantial contribution from litterfall to total atmospheric-Hg deposition. Annual litterfall-Hg deposition in this study had a median of 11.7 μg per square meter per year (μg/m 2 /yr) and ranged from 2.2 to 23.4 μg/m 2 /yr. It closely matched modeled dry-Hg deposition, based on land cover at selected NADP Hg-monitoring sites. Mean annual atmospheric-Hg deposition at forest study sites exhibited a spatial pattern partly explained by statistical differences among five forest-cover types and related to the mapped density of Hg emissions. Forest canopies apparently recorded changes in atmospheric-Hg concentrations over time because litterfall-Hg concentrations decreased year to year and litterfall-Hg concentrations were significantly higher in 2007–2009 than in 2012–2014. These findings reinforce reported decreases in Hg emissions and atmospheric elemental-Hg concentrations during this same time period. Methylmercury (MeHg) was detected in all litterfall samples at all sites, compared with MeHg detections in less than half the precipitation samples at selected sites during the study. These results indicate MeHg in litterfall is a pathway into the terrestrial food web where it can

  3. Atmospheric mercury deposition to forests in the eastern USA.

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

    2017-09-01

    Atmospheric mercury (Hg) deposition to forests is important because half of the land cover in the eastern USA is forest. Mercury was measured in autumn litterfall and weekly precipitation samples at a total of 27 National Atmospheric Deposition Program (NADP) monitoring sites in deciduous and mixed deciduous-coniferous forests in 16 states in the eastern USA during 2007-2014. These simultaneous, uniform, repeated, annual measurements of forest Hg include the broadest area and longest time frame to date. The autumn litterfall-Hg concentrations and litterfall mass at the study sites each year were combined with annual precipitation-Hg data. Rates of litterfall-Hg deposition were higher than or equal to precipitation-Hg deposition rates in 70% of the annual data, which indicates a substantial contribution from litterfall to total atmospheric-Hg deposition. Annual litterfall-Hg deposition in this study had a median of 11.7 μg per square meter per year (μg/m 2 /yr) and ranged from 2.2 to 23.4 μg/m 2 /yr. It closely matched modeled dry-Hg deposition, based on land cover at selected NADP Hg-monitoring sites. Mean annual atmospheric-Hg deposition at forest study sites exhibited a spatial pattern partly explained by statistical differences among five forest-cover types and related to the mapped density of Hg emissions. Forest canopies apparently recorded changes in atmospheric-Hg concentrations over time because litterfall-Hg concentrations decreased year to year and litterfall-Hg concentrations were significantly higher in 2007-2009 than in 2012-2014. These findings reinforce reported decreases in Hg emissions and atmospheric elemental-Hg concentrations during this same time period. Methylmercury (MeHg) was detected in all litterfall samples at all sites, compared with MeHg detections in less than half the precipitation samples at selected sites during the study. These results indicate MeHg in litterfall is a pathway into the terrestrial food web where it can

  4. Net atmospheric mercury deposition to Svalbard: Estimates from lacustrine sediments

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    Drevnick, Paul E.; Yang, Handong; Lamborg, Carl H.; Rose, Neil L.

    2012-11-01

    In this study we used lake sediments, which faithfully record Hg inputs, to derive estimates of net atmospheric Hg deposition to Svalbard, Norwegian Arctic. With the exception of one site affected by local pollution, the study lakes show twofold to fivefold increases in sedimentary Hg accumulation since 1850, likely due to long-range atmospheric transport and deposition of anthropogenic Hg. Sedimentary Hg accumulation in these lakes is a linear function of the ratio of catchment area to lake area, and we used this relationship to model net atmospheric Hg flux: preindustrial and modern estimates are 2.5 ± 3.3 μg m-2 y-1 and 7.0 ± 3.0 μg m-2 y-1, respectively. The modern estimate, by comparison with data for Hg wet deposition, indicates that atmospheric mercury depletion events (AMDEs) or other dry deposition processes contribute approximately half (range 0-70%) of the net flux. Hg from AMDEs may be moving in significant quantities into aquatic ecosystems, where it is a concern because of contamination of aquatic food webs.

  5. A 320 Year Ice-Core Record of Atmospheric Hg Pollution in the Altai, Central Asia.

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    Eyrikh, Stella; Eichler, Anja; Tobler, Leonhard; Malygina, Natalia; Papina, Tatyana; Schwikowski, Margit

    2017-10-17

    Anthropogenic emissions of the toxic heavy metal mercury (Hg) have substantially increased atmospheric Hg levels during the 20th century compared to preindustrial times. However, on a regional scale, atmospheric Hg concentration or deposition trends vary to such an extent during the industrial period that the consequences of recent Asian emissions on atmospheric Hg levels are still unclear. Here we present a 320 year Hg deposition history for Central Asia, based on a continuous high-resolution ice-core Hg record from the Belukha glacier in the Siberian Altai, covering the time period 1680-2001. Hg concentrations and deposition fluxes start rising above background levels at the beginning of the 19th century due to emissions from gold/silver mining and Hg production. A steep increase occurs after the 1940s culminating during the 1970s, at the same time as the maximum Hg use in consumer products in Europe and North America. After a distinct decrease in the 1980s, Hg levels in the 1990s and beginning of the 2000s return to their maximum values, which we attribute to increased Hg emissions from Asia. Thus, rising Hg emissions from coal combustion and artisanal and small-scale gold mining (ASGM) in Asian countries determine recent atmospheric Hg levels in Central Asia, counteracting emission reductions due to control measures in Europe and North America.

  6. Trade-Induced Atmospheric Mercury Deposition over China and Implications for Demand-Side Controls.

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    Chen, Long; Meng, Jing; Liang, Sai; Zhang, Haoran; Zhang, Wei; Liu, Maodian; Tong, Yindong; Wang, Huanhuan; Wang, Wei; Wang, Xuejun; Shu, Jiong

    2018-02-20

    Mercury (Hg) is of global concern because of its adverse effects on humans and the environment. In addition to long-range atmospheric transport, Hg emissions can be geographically relocated through economic trade. Here, we investigate the effect of China's interregional trade on atmospheric Hg deposition over China, using an atmospheric transport model and multiregional input-output analysis. In general, total atmospheric Hg deposition over China is 408.8 Mg yr -1 , and 32% of this is embodied in China's interregional trade, with the hotspots occurring over Gansu, Henan, Hebei, and Yunnan provinces. Interprovincial trade considerably redistributes atmospheric Hg deposition over China, with a range in deposition flux from -104% to +28%. Developed regions, such as the Yangtze River Delta (Shanghai, Jiangsu, and Zhejiang) and Guangdong, avoid Hg deposition over their geographical boundaries, instead causing additional Hg deposition over developing provinces. Bilateral interaction among provinces is strong over some regions, suggesting a need for joint mitigation, such as the Jing-Jin-Ji region (Beijing, Tianjin, and Hebei) and the Yangtze River Delta. Transferring advanced technology from developed regions to their developing trade partners would be an effective measure to mitigate China's Hg pollution. Our findings are relevant to interprovincial efforts to reduce trans-boundary Hg pollution in China.

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

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    Amado Filho, G. M.; Andrade, L. R.; Farina, M.; Malm, O.

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

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

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

    2015-12-01

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

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

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

    2016-01-01

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

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

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

    2002-07-01

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

  11. Just passing through --- high Hg deposition to Puerto Rico forest moves quickly off the landscape

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    Shanley, J. B.; Willenbring, J. K.; Kaste, J. M.; Occhi, M.; McDowell, W. H.

    2012-12-01

    Atmospheric mercury (Hg) in wet deposition at the Luquillo Experimental Forest in northeastern Puerto Rico, averages 28 μg m-2 yr-1, higher than any site in the USA Mercury Deposition Network. Despite the high deposition, Hg content of soils, vegetation, and biota are below global averages. The low Hg content of watershed surfaces, coupled with exceptionally high stream total Hg flux, suggest that most of the Hg passes through the watershed with minimal retention. We assessed Hg dynamics in two adjacent watersheds, Rio Icacos underlain by quartz diorite, and Rio Mameyes underlain by volcaniclastic rocks. At both sites, high-flow Hg concentrations approached 100 ng L-1, dominated by particulate Hg. In order to assess the apparent pass-through nature of Hg in this tropical forest, we measured 7Be and 10Be isotopes from natural, cosmogenic fallout adsorbed on stream suspended particles to constrain the Hg age /residence time and source (atmospheric vs. geogenic or legacy Hg from 19th century gold mining). Ubiquitous 7Be (half-life 53 days) and relatively high 7Be/10Be ratios on suspended particles suggest that stream Hg was dominated by erosion from exposed surfaces, supporting a short residence time. The low watershed retention of the high Hg throughput limits adverse biological effects in this tropical ecosystem.

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

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

    2016-01-01

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

  13. Atmospheric gaseous elemental mercury (GEM concentrations and mercury depositions at a high-altitude mountain peak in south China

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    X. W. Fu

    2010-03-01

    Full Text Available China is regarded as the largest contributor of mercury (Hg to the global atmospheric Hg budget. However, concentration levels and depositions of atmospheric Hg in China are poorly known. Continuous measurements of atmospheric gaseous elemental mercury (GEM were carried out from May 2008 to May 2009 at the summit of Mt. Leigong in south China. Simultaneously, deposition fluxes of THg and MeHg in precipitation, throughfall and litterfall were also studied. Atmospheric GEM concentrations averaged 2.80±1.51 ng m−3, which was highly elevated compared to global background values but much lower than semi-rural and industrial/urban areas in China. Sources identification indicates that both regional industrial emissions and long range transport of Hg from central, south and southwest China were corresponded to the elevated GEM level. Seasonal and diurnal variations of GEM were observed, which reflected variations in source intensity, deposition processes and meteorological factors. Precipitation and throughfall deposition fluxes of THg and MeHg in Mt. Leigong were comparable or lower compared to those reported in Europe and North America, whereas litterfall deposition fluxes of THg and MeHg were higher compared to Europe and North America. This highlights the importance of vegetation to Hg atmospheric cycling. In th remote forest ecosystem of China, deposition of GEM via uptake of foliage followed by litterfall was very important for the depletion of atmospheric Hg. Elevated GEM level in ambient air may accelerate the foliar uptake of Hg through air which may partly explain the elevated litterfall deposition fluxes of Hg observed in Mt. Leigong.

  14. Atmospheric deposition of mercury in central Poland: Sources and seasonal trends

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    Siudek, Patrycja; Kurzyca, Iwona; Siepak, Jerzy

    2016-03-01

    Atmospheric deposition of total mercury was studied at two sites in central Poland, between April 2013 and October 2014. Hg in rainwater (bulk deposition) was analyzed in relation to meteorological parameters and major ions (H+, NO3-, Cl-, SO42 -) in order to investigate seasonal variation, identify sources and determine factors affecting atmospheric Hg chemistry and deposition. Total mercury concentrations varied between 1.24 and 22.1 ng L- 1 at the urban sampling site (Poznań) and between 0.57 and 18.3 ng L- 1 in the woodland protected area (Jeziory), with quite similar mean values of 6.96 and 6.37 ng L- 1, respectively. Mercury in precipitation exhibited lower spatial variability within the study domain (urban/forest transect) than the concentrations determined during other similar observations, reflecting the predominant influence of the same local sources. In our study, a significant seasonal pattern of Hg deposition was observed at both sampling sites, with higher and more variable concentrations of Hg reported for the urban area. In particular, deposition values of Hg were higher in the samples attributed to relatively large precipitation amounts in the summer and in those collected during the winter season (the result of higher contributions from combustion sources, i.e. intensive combustion of fossil fuels in residential and commercial boilers, individual power/heat-generating plants). In addition, a significant relationship between Hg concentration and precipitation amount was found while considering different types of wintertime samples (i.e. rain, snow and mixed precipitation). The analysis of backward trajectories showed that air masses arriving from polluted regions of western Europe and southern Poland largely affected the amount of Hg in rainwater. A seasonal variation in Hg deposition fluxes was also observed, with the maximum value of Hg in spring and minimum in winter. Our results indicated that rainwater Hg and, consequently, the wet deposition

  15. Elevated atmospheric deposition and dynamics of mercury in a remote upland forest of southwestern China

    International Nuclear Information System (INIS)

    Fu Xuewu; Feng Xinbin; Zhu Wanze; Rothenberg, S.; Yao Heng; Zhang Hui

    2010-01-01

    Mt. Gongga area in southwest China was impacted by Hg emissions from industrial activities and coal combustion, and annual means of atmospheric TGM and PHg concentrations at a regional background station were 3.98 ng m -3 and 30.7 pg m -3 , respectively. This work presents a mass balance study of Hg in an upland forest in this area. Atmospheric deposition was highly elevated in the study area, with the annual mean THg deposition flux of 92.5 μg m -2 yr -1 . Total deposition was dominated by dry deposition (71.8%), and wet deposition accounted for the remaining 28.2%. Forest was a large pool of atmospheric Hg, and nearly 76% of the atmospheric input was stored in forest soil. Volatilization and stream outflow were identified as the two major pathways for THg losses from the forest, which yielded mean output fluxes of 14.0 and 8.6 μg m -2 yr -1 , respectively. - Upland forest ecosystem is a great sink of atmospheric mercury in southwest China.

  16. Meteorological effects on Hg wet deposition in a forested site in the Adirondack region of New York during 2000-2015

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    Mao, Huiting; Ye, Zhuyun; Driscoll, Charles

    2017-11-01

    An analysis of weekly measurement data of mercury (Hg) wet deposition was conducted for Huntington Wildlife Forest (HWF), a forest ecosystem in Upstate New York and a biological Hg hotspot, during 2000-2015. Annual accumulated Hg wet deposition flux was found to decrease at a rate of -0.13 μg m-2 yr-1 (2% yr-1) (p = 0.09), and volume weighted mean (VWM) Hg precipitation concentrations at -0.14 ng L-1 yr-1 (2.5% yr-1) (p = 0.00). In examining data by season, no trends were identified for the two variables. It was found that the North Atlantic Oscillation (NAO) affected Hg wet deposition predominantly in spring, as did the position of the U.S. East Coast trough in summer, which suggests different dominant mechanisms driving Hg wet deposition in different seasons. The impacts of such large scale circulation processes were facilitated via variations in precipitation amounts. This was manifested in spring 2011 with the strongest positive phase of NAO, resulting in the wettest spring with the largest Hg wet deposition flux, and in summer 2007 with the U.S. East Coast trough positioned the farthest out over the Atlantic Ocean, causing the driest summer with the lowest Hg wet deposition flux of the study period. Extreme precipitation amounts in spring could singularly drive the overall long-term trend in Hg wet deposition whereas in summer other factors could just be as important. Similar mechanisms were thought to control the long term variations of Hg wet deposition and precipitation concentrations in all seasons but summer as indicated in their significant correlation in all but summer. Atmospheric concentrations of gaseous oxidized mercury (GOM) and particulate borne mercury (PBM) at HWF over 2009-2015 hardly exhibited correlations with Hg wet deposition or precipitation concentrations. Chemical transport model simulations strongly supported efficient scavenging of oxidized Hg by precipitation resulting in the lowest concentration of GOM in the warm season despite the

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

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    Mark D. Cohen

    2016-07-01

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

  18. Chemical cycling and deposition of atmospheric mercury in polar regions: review of recent measurements and comparison with models

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    H. Angot

    2016-08-01

    Full Text Available Mercury (Hg is a worldwide contaminant that can cause adverse health effects to wildlife and humans. While atmospheric modeling traces the link from emissions to deposition of Hg onto environmental surfaces, large uncertainties arise from our incomplete understanding of atmospheric processes (oxidation pathways, deposition, and re-emission. Atmospheric Hg reactivity is exacerbated in high latitudes and there is still much to be learned from polar regions in terms of atmospheric processes. This paper provides a synthesis of the atmospheric Hg monitoring data available in recent years (2011–2015 in the Arctic and in Antarctica along with a comparison of these observations with numerical simulations using four cutting-edge global models. The cycle of atmospheric Hg in the Arctic and in Antarctica presents both similarities and differences. Coastal sites in the two regions are both influenced by springtime atmospheric Hg depletion events and by summertime snowpack re-emission and oceanic evasion of Hg. The cycle of atmospheric Hg differs between the two regions primarily because of their different geography. While Arctic sites are significantly influenced by northern hemispheric Hg emissions especially in winter, coastal Antarctic sites are significantly influenced by the reactivity observed on the East Antarctic ice sheet due to katabatic winds. Based on the comparison of multi-model simulations with observations, this paper discusses whether the processes that affect atmospheric Hg seasonality and interannual variability are appropriately represented in the models and identifies research gaps in our understanding of the atmospheric Hg cycling in high latitudes.

  19. Mobility and contamination assessment of mercury in coal fly ash, atmospheric deposition, and soil collected from Tianjin, China.

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    Wei, Zheng; Wu, Guanghong; Su, Ruixian; Li, Congwei; Liang, Peiyu

    2011-09-01

    Samples of class F coal fly ash (levels I, II, and III), slag, coal, atmospheric deposition, and soils collected from Tianjin, China, were analyzed using U.S. Environmental Protection Agency (U.S. EPA) Method 3052 and a sequential extraction procedure, to investigate the pollution status and mobility of Hg. The results showed that total mercury (HgT) concentrations were higher in level I fly ash (0.304 µg/g) than in level II and level III fly ash and slag (0.142, 0.147, and 0.052 µg/g, respectively). Total Hg in the atmospheric deposition was higher during the heating season (0.264 µg/g) than the nonheating season (0.135 µg/g). Total Hg contents were higher in suburban area soils than in rural and agricultural areas. High HgT concentrations in suburban area soils may be a result of the deposition of Hg associated with particles emitted from coal-fired power plants. Mercury in fly ash primarily existed as elemental Hg, which accounted for 90.1, 85.3, and 90.6% of HgT in levels I, II, and III fly ash, respectively. Mercury in the deposition existed primarily as sulfide Hg, which accounted for 73.8% (heating season) and 74.1% (nonheating season) of HgT. However, Hg in soils existed primarily as sulfide Hg, organo-chelated Hg and elemental Hg, which accounted for 37.8 to 50.0%, 31.7 to 41.8%, and 13.0 to 23.9% of HgT, respectively. The percentage of elemental Hg in HgT occurred in the order fly ash > atmospheric deposition > soils, whereas organo-chelated Hg and sulfide Hg occurred in the opposite order. The present approach can provide a window for understanding and tracing the source of Hg in the environment in Tianjin and the risk associated with Hg bioaccessibility. Copyright © 2011 SETAC.

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

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    Chen, H. S.; Wang, Z. F.; Li, J.; Tang, X.; Ge, B. Z.; Wu, X. L.; Wild, O.; Carmichael, G. R.

    2015-09-01

    Atmospheric mercury (Hg) is a toxic pollutant and can be transported over the whole globe due to its long lifetime in the atmosphere. For the purpose of assessing Hg hemispheric transport and better characterizing regional Hg pollution, a global nested atmospheric Hg transport model (GNAQPMS-Hg - Global Nested Air Quality Prediction Modeling System for Hg) has been developed. In GNAQPMS-Hg, the gas- and aqueous-phase Hg chemistry representing the transformation among three forms of Hg: elemental mercury (Hg(0)), divalent mercury (Hg(II)), and primary particulate mercury (Hg(P)) are calculated. A detailed description of the model, including mercury emissions, gas- and aqueous-phase chemistry, and dry and wet deposition is given in this study. Worldwide observations including extensive data in China have been collected for model evaluation. Comparison results show that the model reasonably simulates the global mercury budget and the spatiotemporal variation of surface mercury concentrations and deposition. Overall, model predictions of annual total gaseous mercury (TGM) and wet deposition agree with observations within a factor of 2, and within a factor of 5 for oxidized mercury and dry deposition. The model performs significantly better in North America and Europe than in East Asia. This can probably be attributed to the large uncertainties in emission inventories, coarse model resolution and to the inconsistency between the simulation and observation periods in East Asia. Compared to the global simulation, the nested simulation shows improved skill at capturing the high spatial variability of surface Hg concentrations and deposition over East Asia. In particular, the root mean square error (RMSE) of simulated Hg wet deposition over East Asia is reduced by 24 % in the nested simulation. Model sensitivity studies indicate that Chinese primary anthropogenic emissions account for 30 and 62 % of surface mercury concentrations and deposition over China, respectively

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

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

    2007-12-01

    We present here the first study of the isotopic composition of Hg in rocks, ore deposits, and active hydrothermal systems from the California Coast Ranges, one of Earth's largest Hg-depositing systems. The Franciscan Complex and Great Valley Sequence, which form the bedrock in the California Coast Ranges, are intruded and overlain by Tertiary volcanic rocks including the Clear Lake Volcanic Sequence. These rocks contain two types of Hg deposits, hot-spring deposits that form at shallow depths (<300 m) and silica-carbonate deposits that extend to greater depths (200 to 1000 m), as well as active springs and geothermal systems that release Hg to the present surface. The Franciscan Complex and Great Valley Sequence contain clastic sedimentary rocks with higher concentrations of Hg than volcanic rocks of the Clear Lake Volcanic Field. Mean Hg isotope compositions for all three rock units are similar, although the range of values in Franciscan Complex rocks is greater than in either Great Valley or Clear Lake rocks. Hot spring and silica-carbonate Hg deposits have similar average isotopic compositions that are indistinguishable from averages for the three rock units, although δ202Hg values for the Hg deposits have a greater variance than the country rocks. Precipitates from dilute spring and saline thermal waters in the area have similarly large variance and a mean δ202Hg value that is significantly lower than the ore deposits and rocks. These observations indicate there is little or no isotopic fractionation during release of Hg from its source rocks into hydrothermal solutions. Isotopic fractionation does appear to take place during transport and concentration of Hg in deposits, especially in their uppermost parts. Boiling of hydrothermal fluids is likely the most important process causing of the observed Hg isotope fractionation. This should result in the release of Hg with low δ202Hg values into the atmosphere from the top of these hydrothermal systems and a

  2. History of atmospheric deposition of Cd, Hg, and Pb in North America: Evidence from lake and peat bog sediments

    International Nuclear Information System (INIS)

    Norton, S.A.; Dillon, P.J.; Evans, R.D.; Mierle, G.; Kahl, J.S.

    1990-01-01

    The precipitation chemistry and lake and peat sediment chemistry of three metals emitted to the atmosphere in significant amounts as a result of anthropogenic activity are reviewed. The three metals, Cd, Hg, and Pb, have contrasting source terms, atmospheric residence times, and chemical mobility. Lake and ombrotrophic peat bog sediments record increases in the concentrations and accumulation rates of the metals for most of temperate North America for the last 100 years. These increases are largely related to the burning of coal, smelting of nonferrous metals, the transportation industry, and the industrial production of chlorine. Modern atmospheric fluxes of Cd in central North America are about 1,000 times background fluxes; accumulation rates for Cd in sediments have increased two to 3 times above background, beginning about 100 years ago. Global scale Hg pollution off the atmosphere is suggested by concentrations in northern hemisphere air that are double the Hg content of southern hemisphere air. Accumulation rates of Hg in sediment have approximately doubled in the last 100 years. However, these rates are approximately an order of magnitude less than those for Cd. Modern increases in Pb concentrations are ubiquitous for all lakes examines thus far in North America. Input is from multiple sources and thus the timing of increased accumulation rates in sediment varies across the continent. Typical modern accumulation rates reach maxima at 20 to 30 mg/sq-m/yr, or 100 times that of Cd and 1,000 times that off Hg. Recent decreases in atmospheric lead are reflected in decreases in the accumulation rate of Pb in both lake and peat bog sediment in eastern North America

  3. The Influence of Climate Change on Atmospheric Deposition of Mercury in the Arctic—A Model Sensitivity Study

    Science.gov (United States)

    Hansen, Kaj M.; Christensen, Jesper H.; Brandt, Jørgen

    2015-01-01

    Mercury (Hg) is a global pollutant with adverse health effects on humans and wildlife. It is of special concern in the Arctic due to accumulation in the food web and exposure of the Arctic population through a rich marine diet. Climate change may alter the exposure of the Arctic population to Hg. We have investigated the effect of climate change on the atmospheric Hg transport to and deposition within the Arctic by making a sensitivity study of how the atmospheric chemistry-transport model Danish Eulerian Hemispheric Model (DEHM) reacts to climate change forcing. The total deposition of Hg to the Arctic is 18% lower in the 2090s compared to the 1990s under the applied Special Report on Emissions Scenarios (SRES-A1B) climate scenario. Asia is the major anthropogenic source area (25% of the deposition to the Arctic) followed by Europe (6%) and North America (5%), with the rest arising from the background concentration, and this is independent of the climate. DEHM predicts between a 6% increase (Status Quo scenario) and a 37% decrease (zero anthropogenic emissions scenario) in Hg deposition to the Arctic depending on the applied emission scenario, while the combined effect of future climate and emission changes results in up to 47% lower Hg deposition. PMID:26378551

  4. Photochemical reactions between mercury (Hg) and dissolved organic matter decrease Hg bioavailability and methylation.

    Science.gov (United States)

    Luo, Hong-Wei; Yin, Xiangping; Jubb, Aaron M; Chen, Hongmei; Lu, Xia; Zhang, Weihua; Lin, Hui; Yu, Han-Qing; Liang, Liyuan; Sheng, Guo-Ping; Gu, Baohua

    2017-01-01

    Atmospheric deposition of mercury (Hg) to surface water is one of the dominant sources of Hg in aquatic environments and ultimately drives methylmercury (MeHg) toxin accumulation in fish. It is known that freshly deposited Hg is more readily methylated by microorganisms than aged or preexisting Hg; however the underlying mechanism of this process is unclear. We report that Hg bioavailability is decreased by photochemical reactions between Hg and dissolved organic matter (DOM) in water. Photo-irradiation of Hg-DOM complexes results in loss of Sn(II)-reducible (i.e. reactive) Hg and up to an 80% decrease in MeHg production by the methylating bacterium Geobacter sulfurreducens PCA. Loss of reactive Hg proceeded at a faster rate with a decrease in the Hg to DOM ratio and is attributed to the possible formation of mercury sulfide (HgS). These results suggest a new pathway of abiotic photochemical formation of HgS in surface water and provide a mechanism whereby freshly deposited Hg is readily methylated but, over time, progressively becomes less available for microbial uptake and methylation. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Spatial patterns and temporal changes in atmospheric-mercury deposition for the midwestern USA, 2001–2016

    Science.gov (United States)

    Risch, Martin R.; Kenski, Donna M.

    2018-01-01

    Spatial patterns and temporal changes in atmospheric-mercury (Hg) deposition were examined in a five-state study area in the Midwestern USA where 32% of the stationary sources of anthropogenic Hg emissions in the continental USA were located. An extensive monitoring record for wet and dry Hg deposition was compiled for 2001–2016, including 4666 weekly precipitation samples at 13 sites and 27 annual litterfall-Hg samples at 7 sites. This study is the first to examine these Hg data for the Midwestern USA. The median annual precipitation-Hg deposition at the study sites was 10.4 micrograms per square meter per year (ug/m2/year) and ranged from 5.8 ug/m2/year to 15.0 ug/m2/year. The median annual Hg concentration was 9.4 ng/L. Annual litterfall-Hg deposition had a median of 16.1 ug/m2/year and ranged from 9.7 to 23.4 ug/m2/year. Isopleth maps of annual precipitation-Hg deposition indicated a recurring spatial pattern similar to one revealed by statistical analysis of weekly precipitation-Hg deposition. In that pattern, high Hg deposition in southeastern Indiana was present each year, frequently extending to southern Illinois. Most of central Indiana and central Illinois had similar Hg deposition. Areas with comparatively lower annual Hg deposition were observed in Michigan and Ohio for many years and frequently included part of northern Indiana. The area in southern Indiana where high Hg deposition predominated had the highest number of extreme episodes of weekly Hg deposition delivering up to 15% of the annual Hg load from precipitation in a single week. Modeled 48-h back trajectories indicated air masses for these episodes often arrived from the south and southwest, crossing numerous stationary sources of Hg emissions releasing from 23 to more than 300 kg Hg per year. This analysis suggests that local and regional, rather than exclusively continental or global Hg emissions were likely contributing to the extreme episodes and at least in part, to the spatial

  6. Loess as an environmental archive of atmospheric trace element deposition

    Science.gov (United States)

    Blazina, T.; Winkel, L. H.

    2013-12-01

    Environmental archives such as ice cores, lake sediment cores, and peat cores have been used extensively to reconstruct past atmospheric deposition of trace elements. These records have provided information about how anthropogenic activities such as mining and fossil fuel combustion have disturbed the natural cycles of various atmospherically transported trace elements (e.g. Pb, Hg and Se). While these records are invaluable for tracing human impacts on such trace elements, they often provide limited information about the long term natural cycles of these elements. An assumption of these records is that the observed variations in trace element input, prior to any assumed anthropogenic perturbations, represent the full range of natural variations. However, records such as those mentioned above which extend back to a maximum of ~400kyr may not capture the potentially large variations of trace element input occurring over millions of years. Windblown loess sediments, often representing atmospheric deposition over time scales >1Ma, are the most widely distributed terrestrial sediments on Earth. These deposits have been used extensively to reconstruct continental climate variability throughout the Quaternary and late Neogene periods. In addition to being a valuable record of continental climate change, loess deposits may represent a long term environmental archive of atmospheric trace element deposition and may be combined with paleoclimate records to elucidate how fluctuations in climate have impacted the natural cycle of such elements. Our research uses the loess-paleosol deposits on the Chinese Loess Plateau (CLP) to quantify how atmospheric deposition of trace elements has fluctuated in central China over the past 6.8Ma. The CLP has been used extensively to reconstruct past changes of East Asian monsoon system (EAM). We present a suite of trace element concentration records (e.g. Pb, Hg, and Se) from the CLP which exemplifies how loess deposits can be used as an

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

    Science.gov (United States)

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

  8. Wading bird guano contributes to Hg accumulation in tree island soils in the Florida Everglades

    International Nuclear Information System (INIS)

    Zhu, Yingjia; Gu, Binhe; Irick, Daniel L.; Ewe, Sharon; Li, Yuncong; Ross, Michael S.; Ma, Lena Q.

    2014-01-01

    Tree islands are habitat for wading birds and a characteristic landscape feature in the Everglades. A total of 93 surface soil and 3 soil core samples were collected from 7 degraded/ghost and 34 live tree islands. The mean Hg concentration in surface soils of ghost tree islands was low and similar to marsh soil. For live tree islands, Hg concentrations in the surface head region were considerably greater than those in mid and tail region, and marsh soils. Hg concentrations in bird guano (286 μg kg −1 ) were significantly higher than those in mammal droppings (105 μg kg −1 ) and plant leaves (53 μg kg −1 ). In addition, Hg concentrations and δ 15 N values displayed positive correlation in soils influenced by guano. During 1998–2010, estimated annual Hg deposition by guano was 148 μg m −2 yr −1 and ∼8 times the atmospheric deposition. Highlights: • Hg concentrations in the head region of tree islands were the highest. • Hg concentrations in bird guano (286 μg kg −1 ) were significantly higher than those in mammal droppings and plant leaves. • Hg concentrations and δ 15 N values showed positive correlation in soils influenced by guano. • Estimated annual Hg deposition by guano was 148 μg m −2 yr −1 , ∼8 times the atmospheric deposition. -- The annual Hg deposition by bird guano to tree island soils in the Everglades was ∼8 times the atmospheric deposition

  9. Atmospheric Metal Pollutants-Archives, Methods, and History

    International Nuclear Information System (INIS)

    Norton, Stephen A.

    2007-01-01

    Pollution of the atmosphere with cadmium (Cd), mercury (Hg), and lead (Pb) is a consequence of human activities. Natural archives are necessary to reconstruct the long-term history of metal deposition because accurate measurement of atmospheric deposition is a recent accomplishment. Reconstructions require: (1) accurate determination of concentrations of elements and isotopes, (2) accurate chronology of archives, and (3) archives that faithfully record atmosphere deposition. The most useful long-term archives are accumulations of ice and snow, peat, and lake sediment. Quantification of Cd deposition is uncommon because of its low concentration and substantial chemical mobility. Nonetheless, trends in peat and lake sediment are similar to those of Hg and Pb since ca. 1800 a.d. Both Hg and Pb are relatively chemically immobile and thus the peat and lake archives are believed to record historic trends of atmospheric deposition. Isotopic and concentration studies of Pb indicate a history of northern hemisphere atmospheric pollution extending back prior to 0 a.d. Although measurements of Hg concentration are now routine, isotopic measurements are in their infancy. Some Hg pollution sources have unique isotopic ratios, thereby contributing unique signals to the total Hg. Maximum accumulation rates of Hg and Pb occur up to 10 years later than for Cd (1970s versus 1960s in eastern North America, perhaps slightly later in Europe). By 2004, deposition of Cd, Hg, and Pb had declined from peak values in eastern North America more than 75, 75, and 90%, respectively

  10. Determination of heavy metal deposition in the county of Obrenovac (Serbia using mosses as bioindicators, III: Copper (Cu, Iron (Fe and Mercury (Hg

    Directory of Open Access Journals (Sweden)

    Sabovljević M.

    2007-01-01

    Full Text Available In this study, the deposition of three heavy metals (Cu, Fe and Hg in four moss taxa (Bryum argenteum, Bryum capillare, Brachythecium sp. and Hypnum cupressiforme in the county of Obrenovac (Serbia is presented. The distribution of average heavy metal content in all mosses in the county of Obrenovac is presented on maps, while long-term atmospheric deposition (in the mosses Bryum argenteum and B. capillare and short-term atmospheric deposition (in the mosses Brachythecium sp. and Hypnum cupressiforme are discussed and given in a table. Areas of the highest contaminations are highlighted.

  11. Atmospheric mercury in northern Wisconsin: sources and species

    International Nuclear Information System (INIS)

    Lamborg, C.H.; Fitzgerald, W.F.; Vandal, G.M.; Rolfhus, K.R.

    1995-01-01

    The atmospheric chemistry, deposition and transport of mercury (Hg) in the Upper Great Lakes region is being investigated at a near-remote sampling location in northern Wisconsin. Intensive sampling over two years has been completed. A multi-phase collection strategy was used to gain insight into the processes controlling concentrations and chemical/physical speciation of atmospheric Hg. Additional chemical and physical atmospheric determinations were also made during these periods to aid in the interpretation of the Hg determinations. For example, correlations of Hg with ozone, sulfur dioxide and synopticscale meteorological features suggest a regionally discernible signal in Hg. Comparison to isosigma backward air parcel trajectories confirms this regionality and implicates the areas south, southeast and northwest of the size to be source for Hg. Particle-phase Hg (Hg p ) was found to be approximately 40% in an oxidized form, or operationally defined as reactive but was variable. Hg p and other particle constituents show significant correlation and similarity in behavior. These observations support the hypothesis that precipitation-phase Hg arises from the scavenging of atmospheric particulates bearing Hg. Observed concentrations of rain and particle-Hg fit the theoretical expectations for nucleation and below-cloud scavenging. Increases in the Hg/aerosol mass ratio appear to take place during transport. Enrichment of aerosols is taken as evidence of gas/particle conversion which could represent the step linking gas-phase Hg with rain. The refined budget indicates ca. 24% of total deposition is from summer particle dry deposition, and that this deposition also contributes ca. 24% of all reactive Hg deposition. Most deposition occurs during the summer months. 40 refs., 4 figs., 7 tabs

  12. Atmospheric deposition exposes Qinling pandas to toxic pollutants.

    Science.gov (United States)

    Chen, Yi-Ping; Zheng, Ying-Juan; Liu, Qiang; Song, Yi; An, Zhi-Sheng; Ma, Qing-Yi; Ellison, Aaron M

    2017-03-01

    The giant panda (Ailuropoda melanoleuca) is one of the most endangered animals in the world, and it is recognized worldwide as a symbol for conservation. A previous study showed that wild and captive pandas, especially those of the Qinling subspecies, were exposed to toxicants in their diet of bamboo; the ultimate origin of these toxicants is unknown. Here we show that atmospheric deposition is the most likely origin of heavy metals and persistent organic pollutants (POPs) in the diets of captive and wild Qinling pandas. Average atmospheric deposition was 199, 115, and 49 g·m -2 ·yr -1 in the center of Xi'an City, at China's Shaanxi Wild Animal Research Center (SWARC), and at Foping National Nature Reserve (FNNR), respectively. Atmospheric deposition of heavy metals (As, Cd, Cr, Pb, Hg, Co, Cu, Zn, Mn, and Ni) and POPs was highest at Xi'an City, intermediate at SWARC, and lowest at FNNR. Soil concentrations of the aforementioned heavy metals other than As and Zn also were significantly higher at SWARC than at FNNR. Efforts to conserve Qinling pandas may be compromised by air pollution attendant to China's economic development. Improvement of air quality and reductions of toxic emissions are urgently required to protect China's iconic species. © 2017 by the Ecological Society of America.

  13. Huguangyan Maar Lake (SE China): A solid record of atmospheric mercury pollution history in a non-remote region

    Science.gov (United States)

    Zeng, Yan; Chen, Jingan; Yang, Yongqiong; Wang, Jianxu; Zhu, Zhengjie; Li, Jian

    2017-10-01

    Mercury is a highly toxic metal that can cause harm to environment and human health. As atmospheric deposition is the main source of total Hg input to aquatic system in remote and pristine regions, almost all the studies on atmospheric Hg pollution history concentrated in these areas, while the studies in non-remote areas are much limited, especially for the long history records. In this study, Huguangyan Maar Lake, an undisturbed lake system at low altitude in China, was selected to reconstruct the atmospheric mercury pollution history. Variation patterns of TOC, Hg and non-residual Sr in the sediment core indicated that, compared to the direct atmospheric Hg deposition, the effect of either Hg scavenging from water column by algae or the catchment inputs of previously deposited Hg on the Hg accumulation in the lake sediment was limited. The sediment Hg content in Huguangyan Lake was mainly controlled by the atmospheric Hg deposition, and thus accurately reflected the atmospheric Hg pollution history. The Hga (Hg content from atmospheric deposition) in Huguangyan Lake presented a comparable variation pattern to that in remote sites. It had the same variation trend as the global atmospheric Hg before 1950 CE, which could be attributed to the Industrial Revolution. After that, it was mainly controlled by Hg emissions from Asian countries. The variation of Hga also indicated that atmospheric Hg deposition accelerated significantly since 2000 CE. This study, along with other investigations in remote sites in China, showed that the sediment Hg in Huguangyan Lake responded to the atmospheric Hg pollution more sensitively than in the alpine regions. It should be noted that, the more intensive acceleration of Hg deposition in Huguangyan Lake may imply that the South of China suffered from much more serious atmospheric Hg pollution than previous studies revealed.

  14. Assessment of Global Mercury Deposition through Litterfall.

    Science.gov (United States)

    Wang, Xun; Bao, Zhengduo; Lin, Che-Jen; Yuan, Wei; Feng, Xinbin

    2016-08-16

    There is a large uncertainty in the estimate of global dry deposition of atmospheric mercury (Hg). Hg deposition through litterfall represents an important input to terrestrial forest ecosystems via cumulative uptake of atmospheric Hg (most Hg(0)) to foliage. In this study, we estimate the quantity of global Hg deposition through litterfall using statistical modeling (Monte Carlo simulation) of published data sets of litterfall biomass production, tree density, and Hg concentration in litter samples. On the basis of the model results, the global annual Hg deposition through litterfall is estimated to be 1180 ± 710 Mg yr(-1), more than two times greater than the estimate by GEOS-Chem. Spatial distribution of Hg deposition through litterfall suggests that deposition flux decreases spatially from tropical to temperate and boreal regions. Approximately 70% of global Hg(0) dry deposition occurs in the tropical and subtropical regions. A major source of uncertainty in this study is the heterogeneous geospatial distribution of available data. More observational data in regions (Southeast Asia, Africa, and South America) where few data sets exist will greatly improve the accuracy of the current estimate. Given that the quantity of global Hg deposition via litterfall is typically 2-6 times higher than Hg(0) evasion from forest floor, global forest ecosystems represent a strong Hg(0) sink.

  15. Pre-industrial and recent (1970-2010) atmospheric deposition of sulfate and mercury in snow on southern Baffin Island, Arctic Canada.

    Science.gov (United States)

    Zdanowicz, Christian; Kruemmel, Eva; Lean, David; Poulain, Alexandre; Kinnard, Christophe; Yumvihoze, Emmanuel; Chen, JiuBin; Hintelmann, Holger

    2015-03-15

    Sulfate (SO4(2-)) and mercury (Hg) are airborne pollutants transported to the Arctic where they can affect properties of the atmosphere and the health of marine or terrestrial ecosystems. Detecting trends in Arctic Hg pollution is challenging because of the short period of direct observations, particularly of actual deposition. Here, we present an updated proxy record of atmospheric SO4(2-) and a new 40-year record of total Hg (THg) and monomethyl Hg (MeHg) deposition developed from a firn core (P2010) drilled from Penny Ice Cap, Baffin Island, Canada. The updated P2010 record shows stable mean SO4(2-) levels over the past 40 years, which is inconsistent with observations of declining atmospheric SO4(2-) or snow acidity in the Arctic during the same period. A sharp THg enhancement in the P2010 core ca 1991 is tentatively attributed to the fallout from the eruption of the Icelandic volcano Hekla. Although MeHg accumulation on Penny Ice Cap had remained constant since 1970, THg accumulation increased after the 1980s. This increase is not easily explained by changes in snow accumulation, marine aerosol inputs or air mass trajectories; however, a causal link may exist with the declining sea-ice cover conditions in the Baffin Bay sector. The ratio of THg accumulation between pre-industrial times (reconstructed from archived ice cores) and the modern industrial era is estimated at between 4- and 16-fold, which is consistent with estimates from Arctic lake sediment cores. The new P2010 THg record is the first of its kind developed from the Baffin Island region of the eastern Canadian Arctic and one of very few such records presently available in the Arctic. As such, it may help to bridge the knowledge gap linking direct observation of gaseous Hg in the Arctic atmosphere and actual net deposition and accumulation in various terrestrial media. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. Tundra uptake of atmospheric elemental mercury drives Arctic mercury pollution.

    Science.gov (United States)

    Obrist, Daniel; Agnan, Yannick; Jiskra, Martin; Olson, Christine L; Colegrove, Dominique P; Hueber, Jacques; Moore, Christopher W; Sonke, Jeroen E; Helmig, Detlev

    2017-07-12

    Anthropogenic activities have led to large-scale mercury (Hg) pollution in the Arctic. It has been suggested that sea-salt-induced chemical cycling of Hg (through 'atmospheric mercury depletion events', or AMDEs) and wet deposition via precipitation are sources of Hg to the Arctic in its oxidized form (Hg(ii)). However, there is little evidence for the occurrence of AMDEs outside of coastal regions, and their importance to net Hg deposition has been questioned. Furthermore, wet-deposition measurements in the Arctic showed some of the lowest levels of Hg deposition via precipitation worldwide, raising questions as to the sources of high Arctic Hg loading. Here we present a comprehensive Hg-deposition mass-balance study, and show that most of the Hg (about 70%) in the interior Arctic tundra is derived from gaseous elemental Hg (Hg(0)) deposition, with only minor contributions from the deposition of Hg(ii) via precipitation or AMDEs. We find that deposition of Hg(0)-the form ubiquitously present in the global atmosphere-occurs throughout the year, and that it is enhanced in summer through the uptake of Hg(0) by vegetation. Tundra uptake of gaseous Hg(0) leads to high soil Hg concentrations, with Hg masses greatly exceeding the levels found in temperate soils. Our concurrent Hg stable isotope measurements in the atmosphere, snowpack, vegetation and soils support our finding that Hg(0) dominates as a source to the tundra. Hg concentration and stable isotope data from an inland-to-coastal transect show high soil Hg concentrations consistently derived from Hg(0), suggesting that the Arctic tundra might be a globally important Hg sink. We suggest that the high tundra soil Hg concentrations might also explain why Arctic rivers annually transport large amounts of Hg to the Arctic Ocean.

  17. Speciation of Hg in lichens

    International Nuclear Information System (INIS)

    Jereb, Vesna; Horvat, Milena

    2002-01-01

    Lichens have long been regarded as a suitable tool for monitoring the relative levels of atmospheric pollutants. Lichens have neither roots, a waxy cuticle nor stomata: hence, for mineral nutrition they are largely dependent on wet and dry deposition from the atmosphere. Moreover, lichens are perennial and can accumulate elements over long periods of time. Therefore, concentrations of elements in lichens represent the average levels of elements in the atmosphere for a long period of time. The epiphytic lichen Hypogymnia physodes is a good bioindicator of air pollution with total mercury (THg). In addition, it contains small amounts of methylmercury (MeHg + ). The first aim of our work was to test analytical techniques for determination of MeHg in lichens taken from different locations in Idrija and reference locations

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

    Directory of Open Access Journals (Sweden)

    M. Amodio

    2014-01-01

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

  19. Chemical bath deposition of Hg doped CdSe thin films and their characterization

    International Nuclear Information System (INIS)

    Bhuse, V.M.

    2005-01-01

    The deliberate addition of Hg in CdSe thin film have been carried out using a simple, modified, chemical bath deposition technique with the objective to study the effect of Hg doping on properties of CdSe thin films. Synthesis was initiated at 278 K temperature using complexed cadmium sulphate, mercuric nitrate and sodium selenosulphate in an aqueous ammonical medium at pH 10. Films were characterized by XRD, SEM, optical absorption, electrical and thermoelectric techniques. The 'as deposited' films were uniform, well adherent, nearly stoichiometric and polycrystalline in a single cubic phase (zinc blende). Crystallite size determined from XRD and SEM was found to increase slightly with addition of Hg. The optical band gap of CdSe remains constant upto 0.05 mol% Hg doping, while it decreases monotonically with further increase in mercury content. Dark dc electrical resistivity and conduction activation energy of CdSe were found to decrease initially upto 0.05 mol% of Hg, thereafter increased for higher values of Hg but remains less than those of CdSe. All the films showed n-type of conductivity. A CdSe film containing 0.05 mol% of Hg showed higher absorption coefficient, and conductivity

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

    Science.gov (United States)

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

    2018-04-01

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

  1. Identification of atmospheric mercury sources and transport pathways on local and regional sales

    Science.gov (United States)

    Gratz, Lynne E.

    Mercury (Hg) is a hazardous air pollutant and bioaccumulative neurotoxin whose intricate atmospheric chemistry complicates our ability to define Hg source-receptor relationships on all scales. Our detailed measurements of Hg in its different forms together with atmospheric tracers have improved our understanding of Hg chemistry and transport. Daily-event precipitation samples collected from 1995 to 2006 in Underhill, VT were examined to identify Hg wet deposition trends and source influences. Analysis revealed that annual Hg deposition at this fairly remote location did not vary significantly over the 12-year period. While a decreasing trend in volume-weighted mean Hg concentration was observed, Hg wet deposition did not decline as transport of emissions from the Midwest and along the Atlantic Coast consistently contributed to the largest observed Hg wet deposition events. Receptor modeling of Hg and trace elements in precipitation indicated that ---60% of Hg wet deposition at Underhill could be attributed to emissions from coal-fired utility boilers (CFUBs), and their contribution to Hg wet deposition did not change significantly over time. Hybrid-receptor modeling further defined these CFUBs to be located predominantly in the Midwestern U.S. Atmospheric Hg chemistry and transport from the Chicago urban/industrial area was the focus of speciated Hg measurements performed in the southern Lake Michigan basin during summer 2007. Transport from Chicago, IL to Holland, MI occurred during 27% of the study period, resulting in a five-fold increase in divalent reactive gaseous Hg (RGM) at the downwind Holland site. Dispersion modeling of case study periods demonstrated that under southwesterly flow approximately half of the RGM in Holland could be attributed to primary RGM emissions from Chicago after transport and dispersion, with the remainder due to Hg0 oxidation in the atmosphere en route. Precipitation and ambient vapor phase samples were also collected in Chicago

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

    Science.gov (United States)

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

    2014-05-01

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

  3. Anthropogenic contributions to atmospheric Hg, Pb and As accumulation recorded by peat cores from southern Greenland and Denmark dated using the 14C "bomb pulse curve"

    Science.gov (United States)

    Shotyk, W.; Goodsite, M. E.; Roos-Barraclough, F.; Frei, R.; Heinemeier, J.; Asmund, G.; Lohse, C.; Hansen, T. S.

    2003-11-01

    Mercury concentrations are clearly elevated in the surface and sub-surface layers of peat cores collected from a minerotrophic ("groundwater-fed") fen in southern Greenland (GL) and an ombrotrophic ("rainwater-fed") bog in Denmark (DK). Using 14C to precisely date samples since ca. AD 1950 using the "atmospheric bomb pulse," the chronology of Hg accumulation in GL is remarkably similar to the bog in DK where Hg was supplied only by atmospheric deposition: this suggests not only that Hg has been supplied to the surface layers of the minerotrophic core (GL) primarily by atmospheric inputs, but also that the peat cores have preserved a consistent record of the changing rates of atmospheric Hg accumulation. The lowest Hg fluxes in the GL core (0.3 to 0.5 μg/m 2/yr) were found in peats dating from AD 550 to AD 975, compared to the maximum of 164 μg/m 2/yr in AD 1953. Atmospheric Hg accumulation rates have since declined, with the value for 1995 (14 μg/m 2/yr) comparable to the value for 1995 obtained by published studies of atmospheric transport modelling (12 μg/m 2/yr). The greatest rates of atmospheric Hg accumulation in the DK core are also found in the sample dating from AD 1953 and are comparable in magnitude (184 μg/m 2/yr) to the GL core; again, the fluxes have since gone into strong decline. The accumulation rates recorded by the peat core for AD 1994 (14 μg/m 2/yr) are also comparable to the value for 1995 obtained by atmospheric transport modelling (18 μg/m 2/yr). Comparing the Pb/Ti and As/Ti ratios of the DK samples with the corresponding crustal ratios (or "natural background values" for preanthropogenic peat) shows that the samples dating from 1953 also contain the maximum concentration of "excess" Pb and As. The synchroneity of the enrichments of all three elements (Hg, Pb, and As) suggests a common source, with coal-burning the most likely candidate. Independent support for this interpretation was obtained from the Pb isotope data ( 206Pb/ 207Pb

  4. Litter mercury deposition in the Amazonian rainforest

    International Nuclear Information System (INIS)

    Fostier, Anne Hélène; Melendez-Perez, José Javier; Richter, Larissa

    2015-01-01

    The objective of this work was to assess the flux of atmospheric mercury transferred to the soil of the Amazonian rainforest by litterfall. Calculations were based on a large survey of published and unpublished data on litterfall and Hg concentrations in litterfall samples from the Amazonian region. Litterfall based on 65 sites located in the Amazon rainforest averaged 8.15 ± 2.25 Mg ha"−"1 y"−"1. Average Hg concentrations were calculated from nine datasets for fresh tree leaves and ten datasets for litter, and a median concentration of 60.5 ng Hg g"−"1 was considered for Hg deposition in litterfall, which averaged 49 ± 14 μg m"−"2 yr"−"1. This value was used to estimate that in the Amazonian rainforest, litterfall would be responsible for the annual removing of 268 ± 77 Mg of Hg, approximately 8% of the total atmospheric Hg deposition to land. The impact of the Amazon deforestation on the Hg biogeochemical cycle is also discussed. - Highlights: • Based on published data we estimated the litterfall in the Amazonian rainforest. • All the published data on Hg concentration in leaves and litter from the region and some unpublished data are presented. • We calculated the litter mercury deposition. • We estimated the contribution of dry, wet and litter Hg deposition in the Amazonian rainforest. • We also discussed the impact of Amazon deforestation on the Hg biogeochemical cycle. - The Amazonian rainforest is responsible for removing at least 268 Mg Hg y"−"1, 8% of the total atmospheric mercury deposition to land.

  5. A synthesis of atmospheric mercury depletion event chemistry in the atmosphere and snow

    Directory of Open Access Journals (Sweden)

    A. J. Poulain

    2008-03-01

    Full Text Available It was discovered in 1995 that, during the spring time, unexpectedly low concentrations of gaseous elemental mercury (GEM occurred in the Arctic air. This was surprising for a pollutant known to have a long residence time in the atmosphere; however conditions appeared to exist in the Arctic that promoted this depletion of mercury (Hg. This phenomenon is termed atmospheric mercury depletion events (AMDEs and its discovery has revolutionized our understanding of the cycling of Hg in Polar Regions while stimulating a significant amount of research to understand its impact to this fragile ecosystem. Shortly after the discovery was made in Canada, AMDEs were confirmed to occur throughout the Arctic, sub-Artic and Antarctic coasts. It is now known that, through a series of photochemically initiated reactions involving halogens, GEM is converted to a more reactive species and is subsequently associated to particles in the air and/or deposited to the polar environment. AMDEs are a means by which Hg is transferred from the atmosphere to the environment that was previously unknown. In this article we review Hg research taken place in Polar Regions pertaining to AMDEs, the methods used to collect Hg in different environmental media, research results of the current understanding of AMDEs from field, laboratory and modeling work, how Hg cycles around the environment after AMDEs, gaps in our current knowledge and the future impacts that AMDEs may have on polar environments. The research presented has shown that while considerable improvements in methodology to measure Hg have been made but the main limitation remains knowing the speciation of Hg in the various media. The processes that drive AMDEs and how they occur are discussed. As well, the role that the snow pack and the sea ice play in the cycling of Hg is presented. It has been found that deposition of Hg from AMDEs occurs at marine coasts and not far inland and that a fraction of the deposited Hg does

  6. Sensitivity model study of regional mercury dispersion in the atmosphere

    Science.gov (United States)

    Gencarelli, Christian N.; Bieser, Johannes; Carbone, Francesco; De Simone, Francesco; Hedgecock, Ian M.; Matthias, Volker; Travnikov, Oleg; Yang, Xin; Pirrone, Nicola

    2017-01-01

    Atmospheric deposition is the most important pathway by which Hg reaches marine ecosystems, where it can be methylated and enter the base of food chain. The deposition, transport and chemical interactions of atmospheric Hg have been simulated over Europe for the year 2013 in the framework of the Global Mercury Observation System (GMOS) project, performing 14 different model sensitivity tests using two high-resolution three-dimensional chemical transport models (CTMs), varying the anthropogenic emission datasets, atmospheric Br input fields, Hg oxidation schemes and modelling domain boundary condition input. Sensitivity simulation results were compared with observations from 28 monitoring sites in Europe to assess model performance and particularly to analyse the influence of anthropogenic emission speciation and the Hg0(g) atmospheric oxidation mechanism. The contribution of anthropogenic Hg emissions, their speciation and vertical distribution are crucial to the simulated concentration and deposition fields, as is also the choice of Hg0(g) oxidation pathway. The areas most sensitive to changes in Hg emission speciation and the emission vertical distribution are those near major sources, but also the Aegean and the Black seas, the English Channel, the Skagerrak Strait and the northern German coast. Considerable influence was found also evident over the Mediterranean, the North Sea and Baltic Sea and some influence is seen over continental Europe, while this difference is least over the north-western part of the modelling domain, which includes the Norwegian Sea and Iceland. The Br oxidation pathway produces more HgII(g) in the lower model levels, but overall wet deposition is lower in comparison to the simulations which employ an O3 / OH oxidation mechanism. The necessity to perform continuous measurements of speciated Hg and to investigate the local impacts of Hg emissions and deposition, as well as interactions dependent on land use and vegetation, forests, peat

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

    Science.gov (United States)

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

    2015-06-01

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

  8. Atmospheric Mercury Deposition to a Remote Islet in the Subtropical Northwest Pacific Ocean

    Science.gov (United States)

    Sheu, G.; Lin, N.

    2013-12-01

    Thirty-four weekly rainwater samples were collected in 2009 at Pengjiayu, a remote islet in the subtropical Northwest (NW) Pacific Ocean with an area of 1.14 km^2, to study the distribution of rainwater mercury (Hg) concentrations and associated wet deposition fluxes. This is the first study concerning wet Hg deposition to the subtropical NW Pacific Ocean downwind of the East Asian continent, which is the major source region for Hg emissions worldwide. Sample Hg concentrations ranged from 2.25 to 22.33 ng L^-1, with a volume-weighted mean (VWM) concentration of 8.85 ng L^-1. The annual wet Hg deposition flux was 10.18 μg m^-2, about 2.5 times the fluxes measured at sites on the Pacific coast of the USA, supporting the hypothesis that deposition is higher in the western than in the eastern Pacific. Seasonal VWM concentrations were 7.23, 11.58, 7.82, and 9.84 ng L^-1, whereas seasonal wet deposition fluxes were 2.14, 3.45, 2.38, and 2.21 μg m^-2, for spring, summer, fall and winter, respectively. Higher summer wet Hg deposition was a function of both higher rainwater Hg concentration and greater rainfall. The seasonal pattern of rainwater Hg concentrations was the opposite of the general seasonal pattern of the East Asian air pollutant export. Since there is no significant anthropogenic Hg emission source on the islet of Pengjiayu, the observed high summertime rainwater Hg concentration hints at the importance of Hg(0) oxidation and/or scavenging of upper-altitude reactive gaseous Hg (RGM) by deep convection. Direct anthropogenic RGM emissions from the East Asian continent may not contribute significantly to the rainwater Hg concentrations, but anthropogenic Hg(0) emissions could be transported to the upper troposphere or marine boundary layer where they can be oxidized to produce RGM, which will then be effectively scavenged by cloud water and rainwater.

  9. Atmospheric deposition of trace elements recorded in snow from the Mt. Nyainqêntanglha region, southern Tibetan Plateau.

    Science.gov (United States)

    Huang, Jie; Kang, Shichang; Zhang, Qianggong; Guo, Junming; Chen, Pengfei; Zhang, Guoshuai; Tripathee, Lekhendra

    2013-08-01

    In May 2009, snowpit samples were collected from a high-elevation glacier in the Mt. Nyainqêntanglha region on the southern Tibetan Plateau. A set of elements (Al, V, Cr, Mn, Co, Ni, Cu, Zn, Cd, Hg and Pb) was analyzed to investigate the concentrations, deposition fluxes of trace elements, and the relative contributions from anthropogenic and natural sources deposited on the southern Tibetan Plateau. Concentrations of most of the trace elements in snowpit samples from the Zhadang glacier are significantly lower than those examined from central Asia (e.g., eastern Tien Shan), with higher concentrations during the non-monsoon season than during the monsoon season. The elements of Al, V, Cr, Mn, Co, and Ni display low crustal enrichment factors (EFs), while Cu, Zn, Cd, Hg, and Pb show high EF values in the snow samples, suggesting anthropogenic inputs are potentially important for these elements in the remote, high-elevation atmosphere on the southern Tibetan Plateau. Together with the fact that the concentration levels of such elements in the Mt. Nyainqêntanglha region are significantly higher than those observed on the south edge of the Tibetan Plateau, our results suggest that the high-elevation atmosphere on the southern Tibetan Plateau may be more sensitive to variations in the anthropogenic emissions of atmospheric trace elements than that in the central Himalayas. Moreover, the major difference between deposition fluxes estimated in our snow samples and those recently measured at Nam Co Station for elements such as Cr and Cu may suggest that atmospheric deposition of some of trace elements reconstructed from snowpits and ice cores could be grossly underestimated on the Tibetan Plateau. Copyright © 2013 Elsevier Ltd. All rights reserved.

  10. The role of ENSO in determining the emission, the speciation and the resulting fate of Hg from Biomass Burning, a lesson from the recent past

    Science.gov (United States)

    De Simone, F.; Hedgecock, I. M.; Cinnirella, S.; Carbone, F.; Sprovieri, F.; Pirrone, N.

    2017-12-01

    The burning of vegetation is an environmental process that impacts the chemical composition of troposphere on a global scale, and has significant consequences on atmospheric pollution and climate. ENSO influences the alternating patterns of drier and wetter periods in almost all continents, therefore causing a rise in, and varying the timing of, fire activity in numerous regions and ecosystems (Le Page et al). A large amount of legacy Hg is currently buffered in different environmental compartments, including soil and vegetation, due to past and current anthropogenic processes and activities. Biomass Burning (BB) is a major source of atmospheric Hg, and a main driver in recycling this legacy Hg which is eventually re-deposited over land and oceans. Hg from BB is emitted mainly as Hg(0)(g), but a large fraction (up to 30% and more) is released as Hg bound to particulate matter, Hg(p), which is more likely to be deposited close to the fire activity (De Simone et al). Thus, speciation is one of the most important factors in determining the redistribution of Hg, and of the subsequent geographical distribution of its atmospheric deposition. Although the drivers controlling speciation remain uncertain, there is evidence that it depends on burn characteristics and fuel moisture content, which depends on the climatological characteristics of the regions where BB occurs (Obrist et al). The areas where atmospheric Hg is deposited depends ultimately on atmospheric transport, transformation and precipitation patterns, hence the fate of Hg emitted from BB is determined by a complex series of interacting processes and mechanisms, which begin with the release of Hg and continue until deposition. Many of these processes are influenced by ENSO. This modeling study analyses the deposition of Hg from BB using different satellite imagery based products, spanning a number of years, characterized by different ENSO regimes, to evaluate how it impacts BB, the speciation of emitted Hg, and

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

    Science.gov (United States)

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

    2015-01-01

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

  12. Deposition of HgTe by electrochemical atomic layer epitaxy (EC-ALE)

    CSIR Research Space (South Africa)

    Venkatasamy, V

    2006-04-01

    Full Text Available This paper describes the first instance of HgTe growth by electrochemical atomic layer epitaxy (EC-ALE). EC-ALE is the electrochemical analog of atomic layer epitaxy (ALE) and atomic layer deposition (ALD), all of which are based on the growth...

  13. Development of a Ground-Based Atmospheric Monitoring Network for the Global Mercury Observation System (GMOS

    Directory of Open Access Journals (Sweden)

    Sprovieri F.

    2013-04-01

    Full Text Available Consistent, high-quality measurements of atmospheric mercury (Hg are necessary in order to better understand Hg emissions, transport, and deposition on a global scale. Although the number of atmospheric Hg monitoring stations has increased in recent years, the available measurement database is limited and there are many regions of the world where measurements have not been extensively performed. Long-term atmospheric Hg monitoring and additional ground-based monitoring sites are needed in order to generate datasets that will offer new insight and information about the global scale trends of atmospheric Hg emissions and deposition. In the framework of the Global Mercury Observation System (GMOS project, a coordinated global observational network for atmospheric Hg is being established. The overall research strategy of GMOS is to develop a state-of-the-art observation system able to provide information on the concentration of Hg species in ambient air and precipitation on the global scale. This network is being developed by integrating previously established ground-based atmospheric Hg monitoring stations with newly established GMOS sites that are located both at high altitude and sea level locations, as well as in climatically diverse regions. Through the collection of consistent, high-quality atmospheric Hg measurement data, we seek to create a comprehensive assessment of atmospheric Hg concentrations and their dependence on meteorology, long-range atmospheric transport and atmospheric emissions.

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

    Science.gov (United States)

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

    2017-02-01

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

  15. Optimization studies of HgSe thin film deposition by electrochemical atomic layer epitaxy (EC-ALE)

    CSIR Research Space (South Africa)

    Venkatasamy, V

    2006-06-01

    Full Text Available Studies of the optimization of HgSe thin film deposition using electrochemical atomic layer epitaxy (EC-ALE) are reported. Cyclic voltammetry was used to obtain approximate deposition potentials for each element. These potentials were then coupled...

  16. Sampling of Atmospheric Precipitation and Deposits for Analysis of Atmospheric Pollution

    OpenAIRE

    Skarżyńska, K.; Polkowska, Ż; Namieśnik, J.

    2006-01-01

    This paper reviews techniques and equipment for collecting precipitation samples from the atmosphere (fog and cloud water) and from atmospheric deposits (dew, hoarfrost, and rime) that are suitable for the evaluation of atmospheric pollution. It discusses the storage and preparation of samples for analysis and also presents bibliographic information on the concentration ranges of inorganic and organic compounds in the precipitation and atmospheric deposit samples.

  17. Atmospheric emissions of F, As, Se, Hg, and Sb from coal-fired power and heat generation in China.

    Science.gov (United States)

    Chen, Jian; Liu, Guijian; Kang, Yu; Wu, Bin; Sun, Ruoyu; Zhou, Chuncai; Wu, Dun

    2013-02-01

    Coal is one of the major energy resources in China, with nearly half of produced Chinese coal used for power and heat generation. The large use of coal for power and heat generation in China may result in significant atmospheric emissions of toxic volatile trace elements (i.e. F, As, Se, Hg, and Sb). For the purpose of estimating the atmospheric emissions from coal-fired power and heat generation in China, a simple method based on coal consumption, concentration and emission factor of trace element was adopted to calculate the gaseous emissions of elements F, As, Se, Hg, and Sb. Results indicate that about 162161, 236, 637, 172, and 33 t F, As, Se, Hg, and Sb, respectively, were introduced into atmosphere from coal combustion by power and heat generation in China in 2009. The atmospheric emissions of F, As, Se, Hg, and Sb by power and heat generation increased from 2005 to 2009 with increasing coal consumptions. Crown Copyright © 2012. Published by Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

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

    2009-12-01

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

  19. Hg Storage and Mobility in Tundra Soils of Northern Alaska

    Science.gov (United States)

    Olson, C.; Obrist, D.

    2017-12-01

    Atmospheric mercury (Hg) can be transported over long distances to remote regions such as the Arctic where it can then deposit and temporarily be stored in soils. This research aims to improve the understanding of terrestrial Hg storage and mobility in the arctic tundra, a large receptor area for atmospheric deposition and a major source of Hg to the Arctic Ocean. We aim to characterize spatial Hg pool sizes across various tundra sites and to quantify the mobility of Hg from thawing tundra soils using laboratory mobility experiments. Active layer and permafrost soil samples were collected in the summer of 2014 and 2015 at the Toolik Field Station in northern Alaska (68° 38' N) and along a 200 km transect extending from Toolik to the Arctic Ocean. Soil samples were analyzed for total Hg concentration, bulk density, and major and trace elements. Hg pool sizes were estimated by scaling up Hg soil concentrations using soil bulk density measurements. Mobility of Hg in tundra soils was quantified by shaking soil samples with ultrapure Milli-Q® water as an extracting solution for 24 and 72 hours. Additionally, meltwater samples were collected for analysis when present. The extracted supernatant was analyzed for total Hg, dissolved organic carbon, cations and anions, redox, and ph. Mobility of Hg from soil was calculated using Hg concentrations determined in solid soil samples and in supernatant of soil solution samples. Results of this study show Hg levels in tundra mineral soils that are 2-5 times higher than those observed at temperate sites closer to pollution sources. Most of the soil Hg was located in mineral horizons where Hg mass accounted for 72% of the total soil pool. Soil Hg pool sizes across the tundra sites were highly variable (166 - 1,365 g ha-1; avg. 419 g ha-1) due to the heterogeneity in soil type, bulk density, depth to frozen layer, and soil Hg concentration. Preliminary results from the laboratory experiment show higher mobility of Hg in mineral

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

    Directory of Open Access Journals (Sweden)

    W. M. Landing

    2010-05-01

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

  1. External quality-assurance project report for the National Atmospheric Deposition Program/National Trends Network and Mercury Deposition Network, 2009-2010

    Science.gov (United States)

    Wetherbee, Gregory A.; Martin, RoseAnn; Rhodes, Mark F.; Chesney, Tanya A.

    2014-01-01

    The U.S. Geological Survey operated six distinct programs to provide external quality-assurance monitoring for the National Atmospheric Deposition Program/National Trends Network (NTN) and Mercury Deposition Network (MDN) during 2009–2010. The field-audit program assessed the effects of onsite exposure, sample handling, and shipping on the chemistry of NTN samples; a system-blank program assessed the same effects for MDN. Two interlaboratory-comparison programs assessed the bias and variability of the chemical analysis data from the Central Analytical Laboratory (CAL) and Mercury (Hg) Analytical Laboratory (HAL). The blind-audit program was also implemented for the MDN to evaluate analytical bias in total Hg concentration data produced by the HAL. The co-located-sampler program was used to identify and quantify potential shifts in NADP data resulting from replacement of original network instrumentation with new electronic recording rain gages (E-gages) and precipitation collectors that use optical sensors. The results indicate that NADP data continue to be of sufficient quality for the analysis of spatial distributions and time trends of chemical constituents in wet deposition across the United States. Results also suggest that retrofit of the NADP networks with the new precipitation collectors could cause –8 to +14 percent shifts in NADP annual precipitation-weighted mean concentrations and total deposition values for ammonium, nitrate, sulfate, and hydrogen ion, and larger shifts (+13 to +74 percent) for calcium, magnesium, sodium, potassium, and chloride. The prototype N-CON Systems bucket collector is more efficient in the catch of precipitation in winter than Aerochem Metrics Model 301 collector, especially for light snowfall.

  2. Temporal changes in the distribution, methylation, and bioaccumulation of newly deposited mercury in an aquatic ecosystem

    Energy Technology Data Exchange (ETDEWEB)

    Orihel, Diane M. [Clayton H. Riddell Faculty of Environment, Earth, and Resources, University of Manitoba, Winnipeg, Manitoba, R3T 2N2 (Canada); Freshwater Institute, Fisheries and Oceans Canada, 501 University Crescent, Winnipeg, Manitoba, R3T 2N6 (Canada)], E-mail: orihel@ualberta.ca; Paterson, Michael J.; Blanchfield, Paul J.; Bodaly, R.A. [Freshwater Institute, Fisheries and Oceans Canada, 501 University Crescent, Winnipeg, Manitoba, R3T 2N6 (Canada); Gilmour, Cynthia C. [Smithsonian Environmental Research Center, 647 Contees Wharf Road, Edgewater, MD 21037 (United States); Hintelmann, Holger [Department of Chemistry, Trent University, 1600 West Bank Drive, Peterborough, Ontario, K9J 7B8 (Canada)

    2008-07-15

    Our objective was to examine how the behavior of atmospheric mercury (Hg) deposited to boreal lake mesocosms changed over time. We added inorganic Hg enriched in a different stable isotope in each of two years, which allowed us to differentiate between Hg added in the first and second year. Although inorganic Hg and methylmercury (MeHg) continued to accumulate in sediments throughout the experiment, the availability of MeHg to the food web declined within one year. This decrease was detected in periphyton, zooplankton, and water mites, but not in gomphid larvae, amphipods, or fish. We suggest that reductions in atmospheric Hg deposition should lead to decreases in MeHg concentrations in biota, but that changes will be more easily detected in short-lived pelagic species than long-lived species associated with benthic food webs. - Mercury deposited to aquatic ecosystems becomes less available for uptake by biota over time.

  3. Atmospheric deposition 2000. NOVA 2003; Atmosfaerisk deposition 2000. NOVA 2003

    Energy Technology Data Exchange (ETDEWEB)

    Ellermann, T.; Hertel, O.; Hovmand, M.F.; Kemp, K.; Skjoeth, C.A.

    2001-11-01

    This report presents measurements and calculations from the atmospheric part of NOVA 2003 and covers results for 2000. It summarises the main results concerning concentrations and depositions of nitrogen, phosphorus and sulphur compounds related to eutrophication and acidification. Depositions of atmospheric compounds to Danish marine waters as well as land surface are presented. Measurements: In 2000 the monitoring program consisted of eight stations where wet deposition of ammonium, nitrate, phosphate (semi quantitatively) and sulphate were measured using bulk precipitation samplers. Six of the stations had in addition measurements of atmospheric content of A, nitrogen, phosphorus, and sulphur compounds in gas and particulate phase carried out by use of filter pack samplers. Filters were analysed at the National Environmental Research Institute. Furthermore nitrogen dioxide were measured using nitrogen dioxide filter samplers and monitors. Model calculations: The measurements in the monitoring program were supplemented with model calculations of concentrations and depositions of nitrogen and sulphur compounds to Danish land surface, marine waters, fjords and bays using the ACDEP model (Atmospheric Chemistry and Deposition). The model is a so-called trajectory model and simulates the physical and chemical processes in the atmosphere using meteorological and emission data as input. The advantage of combining measurements with model calculations is that the strengths of both methods is obtained. Conclusions concerning: 1) actual concentration levels at the monitoring stations, 2) deposition at the monitoring stations, 3) seasonal variations and 4) long term trends in concentrations and depositions are mainly based on the direct measurements. These are furthermore used to validate the results of the model calculations. Calculations and conclusions concerning: 1) depositions to land surface and to the individual marine water, 2) contributions from different emission

  4. Litter mercury deposition in the Amazonian rainforest.

    Science.gov (United States)

    Fostier, Anne Hélène; Melendez-Perez, José Javier; Richter, Larissa

    2015-11-01

    The objective of this work was to assess the flux of atmospheric mercury transferred to the soil of the Amazonian rainforest by litterfall. Calculations were based on a large survey of published and unpublished data on litterfall and Hg concentrations in litterfall samples from the Amazonian region. Litterfall based on 65 sites located in the Amazon rainforest averaged 8.15 ± 2.25 Mg ha(-1) y(-1). Average Hg concentrations were calculated from nine datasets for fresh tree leaves and ten datasets for litter, and a median concentration of 60.5 ng Hg g(-1) was considered for Hg deposition in litterfall, which averaged 49 ± 14 μg m(-2) yr(-1). This value was used to estimate that in the Amazonian rainforest, litterfall would be responsible for the annual removing of 268 ± 77 Mg of Hg, approximately 8% of the total atmospheric Hg deposition to land. The impact of the Amazon deforestation on the Hg biogeochemical cycle is also discussed. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. Achieving uniform layer deposition by atmospheric-pressure plasma-enhanced chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jae-Ok [Department of Plasma Engineering, Korea Institute of Machinery & Materials (KIMM), Daejeon 305-343 (Korea, Republic of); Kang, Woo Seok, E-mail: kang@kimm.re.kr [Department of Plasma Engineering, Korea Institute of Machinery & Materials (KIMM), Daejeon 305-343 (Korea, Republic of); Department of Environment & Energy Mechanical Engineering, University of Science & Technology (UST), Daejeon 305-350 (Korea, Republic of); Hur, Min; Lee, Jin Young [Department of Plasma Engineering, Korea Institute of Machinery & Materials (KIMM), Daejeon 305-343 (Korea, Republic of); Song, Young-Hoon [Department of Plasma Engineering, Korea Institute of Machinery & Materials (KIMM), Daejeon 305-343 (Korea, Republic of); Department of Environment & Energy Mechanical Engineering, University of Science & Technology (UST), Daejeon 305-350 (Korea, Republic of)

    2015-12-31

    This work investigates the use of plasma-enhanced chemical vapor deposition under atmospheric pressure for achieving uniform layer formation. Electrical and optical measurements demonstrated that the counterbalance between oxygen and precursors maintained the homogeneous discharge mode, while creating intermediate species for layer deposition. Several steps of the deposition process of the layers, which were processed on a stationary stage, were affected by flow stream and precursor depletion. This study showed that by changing the flow streamlines using substrate stage motion uniform layer deposition under atmospheric pressure can be achieved. - Highlights: • Zirconium oxide was deposited by atmospheric-pressure plasma-enhanced chemical vapor deposition. • Homogeneous plasma was maintained by counterbalancing between discharge gas and precursors. • Several deposition steps were observed affected by the gas flow stream and precursor depletion. • Thin film layer was uniformly grown when the substrate underwent a sweeping motion.

  6. Assessment of atmospheric heavy metal deposition in the Tarkwa gold mining area of Ghana using epiphytic lichens

    Energy Technology Data Exchange (ETDEWEB)

    Boamponsem, L.K. [Department of Theoretical and Applied Biology, College of Science, Kwame Nkrumah University of Science and Technology, University Post Office, Kumasi (Ghana); Department of Laboratory Technology, School of Physical Sciences, University of Cape Coast, Cape Coast (Ghana); Adam, J.I. [Department of Theoretical and Applied Biology, College of Science, Kwame Nkrumah University of Science and Technology, University Post Office, Kumasi (Ghana); Dampare, S.B., E-mail: dampare@cc.okayama-u.ac.j [National Nuclear Research Institute, Ghana Atomic Energy Commission, P.O. Box LG 80, Legon-Accra (Ghana); Department of Earth Sciences, Okayama University, 1-1, Tsushima-Naka 3-Chome, Okayama 700-8530 (Japan); Nyarko, B.J.B. [National Nuclear Research Institute, Ghana Atomic Energy Commission, P.O. Box LG 80, Legon-Accra (Ghana); Essumang, D.K. [Department of Laboratory Technology, School of Physical Sciences, University of Cape Coast, Cape Coast (Ghana)

    2010-05-01

    In situ lichens (Parmelia sulcata) have been used to assess atmospheric heavy metal deposition in the Tarkwa gold mining area of Ghana. Total heavy metal concentrations obtained by instrumental neutron activation analysis (INAA) were processed by positive matrix factorization (PMF), principal component (PCA) and cluster (CA) analyses. The pollution index factor (PIF) and pollution load index (PLI) criteria revealed elevated levels of Sb, Mn, Cu, V, Al, Co, Hg, Cd and As in excess of the background values. The PCA and CA classified the examined elements into anthropogenic and natural sources, and PMF resolved three primary sources/factors: agricultural activities and other non-point anthropogenic origins, natural soil dust, and gold mining activities. Gold mining activities, which are characterized by dominant species of Sb, Th, As, Hg, Cd and Co, and significant contributions of Cu, Al, Mn and V, are the main contributors of heavy metals in the atmosphere of the study area.

  7. Assessment of atmospheric heavy metal deposition in the Tarkwa gold mining area of Ghana using epiphytic lichens

    International Nuclear Information System (INIS)

    Boamponsem, L.K.; Adam, J.I.; Dampare, S.B.; Nyarko, B.J.B.; Essumang, D.K.

    2010-01-01

    In situ lichens (Parmelia sulcata) have been used to assess atmospheric heavy metal deposition in the Tarkwa gold mining area of Ghana. Total heavy metal concentrations obtained by instrumental neutron activation analysis (INAA) were processed by positive matrix factorization (PMF), principal component (PCA) and cluster (CA) analyses. The pollution index factor (PIF) and pollution load index (PLI) criteria revealed elevated levels of Sb, Mn, Cu, V, Al, Co, Hg, Cd and As in excess of the background values. The PCA and CA classified the examined elements into anthropogenic and natural sources, and PMF resolved three primary sources/factors: agricultural activities and other non-point anthropogenic origins, natural soil dust, and gold mining activities. Gold mining activities, which are characterized by dominant species of Sb, Th, As, Hg, Cd and Co, and significant contributions of Cu, Al, Mn and V, are the main contributors of heavy metals in the atmosphere of the study area.

  8. Sensitivity of stream methyl Hg concentrations to environmental change in the Adirondack mountains of New York, USA

    Science.gov (United States)

    Doug Burns; Karen Riva Murray; Elizabeth A. Nystrom; David M. Wolock; Geofrey Millard; Charles T. Driscoll

    2016-01-01

    The Adirondacks of New York have high levels of mercury (Hg) bioaccumulation as demonstrated by a region-wide fish consumption advisory for children and women who may become pregnant. The source of this Hg is atmospheric deposition that originates from regional, continental, and global emissions.

  9. Thermal stability of atomic layer deposition Al2O3 film on HgCdTe

    Science.gov (United States)

    Zhang, P.; Sun, C. H.; Zhang, Y.; Chen, X.; He, K.; Chen, Y. Y.; Ye, Z. H.

    2015-06-01

    Thermal stability of Atomic Layer Deposition Al2O3 film on HgCdTe was investigated by Al2O3 film post-deposition annealing treatment and Metal-Insulator-Semiconductor device low-temperature baking treatment. The effectiveness of Al2O3 film was evaluated by measuring the minority carrier lifetime and capacitance versus voltage characteristics. After annealing treatment, the minority carrier lifetime of the HgCdTe sample presented a slight decrease. Furthermore, the fixed charge density and the slow charge density decreased significantly in the annealed MIS device. After baking treatment, the fixed charge density and the slow charge density of the unannealed and annealed MIS devices decreased and increased, respectively.

  10. Characterizations of wet mercury deposition on a remote high-elevation site in the southeastern Tibetan Plateau.

    Science.gov (United States)

    Huang, Jie; Kang, Shichang; Zhang, Qianggong; Guo, Junming; Sillanpää, Mika; Wang, Yongjie; Sun, Shiwei; Sun, Xuejun; Tripathee, Lekhendra

    2015-11-01

    Accurate measurements of wet mercury (Hg) deposition are critically important for the assessment of ecological responses to pollutant loading. The Hg in wet deposition was measured over a 3-year period in the southeastern Tibetan Plateau. The volume-weighted mean (VWM) total Hg (HgT) concentration was somewhat lower than those reported in other regions of the Tibetan Plateau, but the VWM methyl-Hg concentration and deposition flux were among the highest globally reported values. The VWM HgT concentration was higher in non-monsoon season than in monsoon season, and wet HgT deposition was dominated by the precipitation amount rather than the scavenging of atmospheric Hg by precipitation. The dominant Hg species in precipitation was mainly in the form of dissolved Hg, which indicates the pivotal role of reactive gaseous Hg within-cloud scavenging to wet Hg deposition. Moreover, an increasing trend in precipitation Hg concentrations was synchronous with the recent economic development in South Asia. Copyright © 2015 Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

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

    2014-07-01

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

  12. Mercury from combustion sources: a review of the chemical species emitted and their transport in the atmosphere

    International Nuclear Information System (INIS)

    Carpi, A.

    1997-01-01

    Different species of mercury have different physical/chemical properties and thus behave quite differentially in air pollution control equipment and in the atmosphere. In general, emission of mercury from coal combustion sources are approximately 20-50% elemental mercury (Hg 0 ) and 50-80% divalent mercury (Hg(II)), which may be predominantly HgCl 2 . Emissions of mercury from waste incinerators are approximately 10-20% Hg 0 and 75-85% Hg(II). The partitioning of mercury in flue gas between the elemental and divalent forms may be dependent on the concentration of particulate carbon, HCl and other pollutants in the stack emissions. The emission of mercury from combustion facilities depends on the species in the exhaust stream and the type of air pollution control equipment used at the source. Air pollution control equipment for mercury removal at combustion facilities includes activated carbon injection, sodium sulfide injection and wet lime/limestone flue gas desulfurization. White Hg(II) is water-soluble and may be removed form the atmosphere by wet and dry deposition close to the combustion sources, the combination of a high vapor pressure and low water-solubility facilitate the long-range transport of Hg 0 in the atmosphere. Background mercury in the atmosphere is predominantly Hg 0 . Elemental mercury is eventually removed from the atmosphere by dry deposition onto surfaces and by wet deposition after oxidation to water-soluble, divalent mercury. 62 refs., 2 figs., 1 tab

  13. Recent Advances in Atmospheric Chemistry of Mercury

    Directory of Open Access Journals (Sweden)

    Lin Si

    2018-02-01

    Full Text Available Mercury is one of the most toxic metals and has global importance due to the biomagnification and bioaccumulation of organomercury via the aquatic food web. The physical and chemical transformations of various mercury species in the atmosphere strongly influence their composition, phase, transport characteristics and deposition rate back to the ground. Modeling efforts to assess global cycling of mercury require an accurate understanding of atmospheric mercury chemistry. Yet, there are several key uncertainties precluding accurate modeling of physical and chemical transformations. We focus this article on recent studies (since 2015 on improving our understanding of the atmospheric chemistry of mercury. We discuss recent advances in determining the dominant atmospheric oxidant of elemental mercury (Hg0 and understanding the oxidation reactions of Hg0 by halogen atoms and by nitrate radical (NO3—in the aqueous reduction of oxidized mercury compounds (HgII as well as in the heterogeneous reactions of Hg on atmospheric-relevant surfaces. The need for future research to improve understanding of the fate and transformation of mercury in the atmosphere is also discussed.

  14. MEAD Marine Effects of Atmospheric Deposition

    Science.gov (United States)

    Jickells, T.; Spokes, L.

    2003-04-01

    The coastal seas are one of the most valuable resources on the planet but they are threatened by human activity. We rely on the coastal area for mineral resources, waste disposal, fisheries and recreation. In Europe, high population densities and high levels of industrial activity mean that the pressures arising from these activities are particularly acute. One of the main problems concerning coastal seas is the rapid increase in the amounts of nitrogen-based pollutants entering the water. They come from many sources, the most important ones being traffic, industry and agriculture. These pollutants can be used by algae as nutrients. The increasing concentrations of these nutrients have led to excessive growth of algae, some of which are harmful. When algae die and decay, oxygen in the water is used up and the resulting lower levels of oxygen may lead to fish kills. Human activity has probably doubled the amount of chemically and biologically reactive nitrogen present globally. In Europe the increases have been greater than this, leading to real concern over the health of coastal waters. Rivers have, until recently, been thought to be the most important source of reactive nitrogen to the coastal seas but we now know that inputs from the atmosphere are large and can equal, or exceed, those from the rivers. Our initial hypothesis was that atmospheric inputs are important and potentially different in their effect on coastal ecosystems to riverine inputs and hence require different management strategies. However, we had almost no information on the direct effects of atmospheric deposition on marine ecosystems, though clearly such a large external nitrogen input should lead to enhanced phytoplankton growth The aim of this European Union funded MEAD project has been to determine how inputs of nitrogen from the atmosphere affect the chemistry and biology of coastal waters. To try to answer this, we have conducted field experiments in the Kattegat, an area where we know

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-01-01

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

  16. High Mercury Wet Deposition at a "Clean Air" Site in Puerto Rico.

    Science.gov (United States)

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

    2015-10-20

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

  17. Impact of Atmospheric Long Range Transport of Lead, Mercury and Cadmium on the Swedish Forest Environment

    International Nuclear Information System (INIS)

    Johansson, K.; Bergbaeck, B.; Tyler, G.

    2001-01-01

    Emissions of Hg, Pb, and Cd to air are transported over wide areas in Europe and deposited far away from their sources. About 80% of the atmospheric deposition of these metals in south Sweden originate from emissions in other countries. As a result of the increased anthropogenic deposition the concentrations of Hg, Pb, and Cd in the morlayer of forest soils have increased considerably, mainly during the 20th century. Although the atmospheric deposition of these elements has declined during the most recent decades, the reduction of the input of Hg and Pb is not sufficient to prevent a further accumulation. The concentrations of Hg and Pb are still increasing by ca. 0.5and ca. 0.2% annually in the surface layer of forest soils.In contrast, the Cd concentration is currently decreasing in a large part of Sweden as a result of both deposition decreases and enhanced leaching induced by soil acidification. The accumulation factors of Hg and Pb, especially in the forest topsoils of south Sweden, are already above those at which adverse effects on soil biological processes and organisms have been demonstrated in studies of gradients from local emission sources and laboratory assessment. There are also indications of such effects at the current regional concentrations of Hg and Pbin mor layers from south Sweden, judging from observations in field and laboratory studies. There is an apparent risk of Pb induced reduction in microbial activity over parts of south Sweden. This might cause increased accumulation of organic matter and a reduced availability of soil nutrients. At current concentrations of Hg in Swedish forest soils,effects similar to those of Pb are likely. Increased concentrations of these elements in organs of mammals and birds have also been measured, though decreases have been demonstrated in recent years, related to changes in atmospheric deposition rates. As a result of current and past deposition in south Sweden, concentrations of Hg in fish have increased

  18. Feedback mechanisms between snow and atmospheric mercury: Results and observations from field campaigns on the Antarctic plateau.

    Science.gov (United States)

    Spolaor, Andrea; Angot, Hélène; Roman, Marco; Dommergue, Aurélien; Scarchilli, Claudio; Vardè, Massimiliano; Del Guasta, Massimo; Pedeli, Xanthi; Varin, Cristiano; Sprovieri, Francesca; Magand, Olivier; Legrand, Michel; Barbante, Carlo; Cairns, Warren R L

    2018-04-01

    The Antarctic Plateau snowpack is an important environment for the mercury geochemical cycle. We have extensively characterized and compared the changes in surface snow and atmospheric mercury concentrations that occur at Dome C. Three summer sampling campaigns were conducted between 2013 and 2016. The three campaigns had different meteorological conditions that significantly affected mercury deposition processes and its abundance in surface snow. In the absence of snow deposition events, the surface mercury concentration remained stable with narrow oscillations, while an increase in precipitation results in a higher mercury variability. The Hg concentrations detected confirm that snowfall can act as a mercury atmospheric scavenger. A high temporal resolution sampling experiment showed that surface concentration changes are connected with the diurnal solar radiation cycle. Mercury in surface snow is highly dynamic and it could decrease by up to 90% within 4/6 h. A negative relationship between surface snow mercury and atmospheric concentrations has been detected suggesting a mutual dynamic exchange between these two environments. Mercury concentrations were also compared with the Br concentrations in surface and deeper snow, results suggest that Br could have an active role in Hg deposition, particularly when air masses are from coastal areas. This research presents new information on the presence of Hg in surface and deeper snow layers, improving our understanding of atmospheric Hg deposition to the snow surface and the possible role of re-emission on the atmospheric Hg concentration. Copyright © 2018 Elsevier Ltd. All rights reserved.

  19. Dry deposition fluxes and deposition velocities of trace metals in the Tokyo metropolitan area measured with a water surface sampler.

    Science.gov (United States)

    Sakata, Masahiro; Marumoto, Kohji

    2004-04-01

    Dry deposition fluxes and deposition velocities (=deposition flux/atmospheric concentration) for trace metals including Hg, Cd, Cu, Mn, Pb, and Zn in the Tokyo metropolitan area were measured using an improved water surface sampler. Mercury is deposited on the water surface in both gaseous (reactive gaseous mercury, RGM) and particulate (particulate mercury, Hg(p)) forms. The results based on 1 yr observations found that dry deposition plays a significant if not dominant role in trace metal deposition in this urban area, contributing fluxes ranging from 0.46 (Cd) to 3.0 (Zn) times those of concurrent wet deposition fluxes. The deposition velocities were found to be dependent on the deposition of coarse particles larger than approximately 5 microm in diameter on the basis of model calculations. Our analysis suggests that the 84.13% diameter is a more appropriate index for each deposited metal than the 50% diameter in the assumed undersize log-normal distribution, because larger particles are responsible for the flux. The deposition velocities for trace metals other than mercury increased exponentially with an increase in their 84.13% diameters. Using this regression equation, the deposition velocities for Hg(p) were estimated from its 84.13% diameter. The deposition fluxes for Hg(p) calculated from the estimated velocities tended to be close to the mercury fluxes measured with the water surface sampler during the study periods except during summer.

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

    Science.gov (United States)

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

    2015-01-01

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

  1. Patterned deposition by atmospheric pressure plasma-enhanced spatial atomic layer deposition

    NARCIS (Netherlands)

    Poodt, P.; Kniknie, B.J.; Branca, A.; Winands, G.J.J.; Roozeboom, F.

    2011-01-01

    An atmospheric pressure plasma enhanced atomic layer deposition reactor has been developed, to deposit Al2O3 films from trimethyl aluminum and an He/O2 plasma. This technique can be used for 2D patterned deposition in a single in-line process by making use of switched localized plasma sources. It

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

    Science.gov (United States)

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

    2014-07-15

    The global-regional climate-air pollution modeling system (GRE-CAPS) was applied over the eastern United States to study the impact of climate change on the concentration and deposition of atmospheric mercury. Summer and winter periods (300 days for each) were simulated, and the present-day model predictions (2000s) were compared to the future ones (2050s) assuming constant emissions. Climate change affects Hg(2+) concentrations in both periods. On average, atmospheric Hg(2+) levels are predicted to increase in the future by 3% in summer and 5% in winter respectively due to enhanced oxidation of Hg(0) under higher temperatures. The predicted concentration change of Hg(2+) was found to vary significantly in space due to regional-scale changes in precipitation, ranging from -30% to 30% during summer and -20% to 40% during winter. Particulate mercury, Hg(p) has a similar spatial response to climate change as Hg(2+), while Hg(0) levels are not predicted to change significantly. In both periods, the response of mercury deposition to climate change varies spatially with an average predicted increase of 6% during summer and 4% during winter. During summer, deposition increases are predicted mostly in the western parts of the domain while mercury deposition is predicted to decrease in the Northeast and also in many areas in the Midwest and Southeast. During winter mercury deposition is predicted to change from -30% to 50% mainly due to the changes in rainfall and the corresponding changes in wet deposition. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Characterizations of wet mercury deposition on a remote high-elevation site in the southeastern Tibetan Plateau

    International Nuclear Information System (INIS)

    Huang, Jie; Kang, Shichang; Zhang, Qianggong; Guo, Junming; Sillanpää, Mika; Wang, Yongjie; Sun, Shiwei

    2015-01-01

    Accurate measurements of wet mercury (Hg) deposition are critically important for the assessment of ecological responses to pollutant loading. The Hg in wet deposition was measured over a 3-year period in the southeastern Tibetan Plateau. The volume-weighted mean (VWM) total Hg (Hg_T) concentration was somewhat lower than those reported in other regions of the Tibetan Plateau, but the VWM methyl-Hg concentration and deposition flux were among the highest globally reported values. The VWM Hg_T concentration was higher in non-monsoon season than in monsoon season, and wet Hg_T deposition was dominated by the precipitation amount rather than the scavenging of atmospheric Hg by precipitation. The dominant Hg species in precipitation was mainly in the form of dissolved Hg, which indicates the pivotal role of reactive gaseous Hg within-cloud scavenging to wet Hg deposition. Moreover, an increasing trend in precipitation Hg concentrations was synchronous with the recent economic development in South Asia. - Highlights: • The lowest Hg_T concentration in precipitation was found at Southeast Tibet Station. • MeHg concentration and wet deposition flux were among the highest at our study site. • Hg_D dominated the concentration and flux of Hg_T in wet Hg deposition. • A long-term increasing trend in the Hg_T concentration was found at our study site. - An increasing trend in the precipitation Hg concentrations was synchronous with the recent economic development in South Asia.

  4. Methodology and significance of studies of atmospheric deposition in highway runoff

    Science.gov (United States)

    Colman, John A.; Rice, Karen C.; Willoughby, Timothy C.

    2001-01-01

    Atmospheric deposition and the processes that are involved in causing and altering atmospheric deposition in relation to highway surfaces and runoff were evaluated nationwide. Wet deposition is more easily monitored than dry deposition, and data on wet deposition are available for major elements and water properties (constituents affecting acid deposition) from the inter-agency National Atmospheric Deposition Program/ National Trends Network (NADP/NTN). Many trace constituents (metals and organic compounds) of interest in highway runoff loads, however, are not included in the NADP/NTN. Dry deposition, which constitutes a large part of total atmospheric deposition for many constituents in highway runoff loads, is difficult to monitor accurately. Dry-deposition rates are not widely available.Many of the highway-runoff investigations that have addressed atmospheric-deposition sources have had flawed investigative designs or problems with methodology. Some results may be incorrect because of reliance on time-aggregated data collected during a period of changing atmospheric emissions. None of the investigations used methods that could accurately quantify the part of highway runoff load that can be attributed to ambient atmospheric deposition. Lack of information about accurate ambient deposition rates and runoff loads was part of the problem. Samples collected to compute the rates and loads were collected without clean-sampling methods or sampler protocols, and without quality-assurance procedures that could validate the data. Massbudget calculations comparing deposition and runoff did not consider loss of deposited material during on-highway processing. Loss of deposited particles from highway travel lanes could be large, as has been determined in labeled particle studies, because of resuspension caused by turbulence from passing traffic. Although a cause of resuspension of large particles, traffic turbulence may increase the rate of deposition for small particles and

  5. A vegetation control on seasonal variations in global atmospheric mercury concentrations

    Science.gov (United States)

    Jiskra, Martin; Sonke, Jeroen E.; Obrist, Daniel; Bieser, Johannes; Ebinghaus, Ralf; Myhre, Cathrine Lund; Pfaffhuber, Katrine Aspmo; Wängberg, Ingvar; Kyllönen, Katriina; Worthy, Doug; Martin, Lynwill G.; Labuschagne, Casper; Mkololo, Thumeka; Ramonet, Michel; Magand, Olivier; Dommergue, Aurélien

    2018-04-01

    Anthropogenic mercury emissions are transported through the atmosphere as gaseous elemental mercury (Hg(0)) before they are deposited to Earth's surface. Strong seasonality in atmospheric Hg(0) concentrations in the Northern Hemisphere has been explained by two factors: anthropogenic Hg(0) emissions are thought to peak in winter due to higher energy consumption, and atmospheric oxidation rates of Hg(0) are faster in summer. Oxidation-driven Hg(0) seasonality should be equally pronounced in the Southern Hemisphere, which is inconsistent with observations of constant year-round Hg(0) levels. Here, we assess the role of Hg(0) uptake by vegetation as an alternative mechanism for driving Hg(0) seasonality. We find that at terrestrial sites in the Northern Hemisphere, Hg(0) co-varies with CO2, which is known to exhibit a minimum in summer when CO2 is assimilated by vegetation. The amplitude of seasonal oscillations in the atmospheric Hg(0) concentration increases with latitude and is larger at inland terrestrial sites than coastal sites. Using satellite data, we find that the photosynthetic activity of vegetation correlates with Hg(0) levels at individual sites and across continents. We suggest that terrestrial vegetation acts as a global Hg(0) pump, which can contribute to seasonal variations of atmospheric Hg(0), and that decreasing Hg(0) levels in the Northern Hemisphere over the past 20 years can be partly attributed to increased terrestrial net primary production.

  6. Source apportionment of atmospheric mercury pollution in China using the GEOS-Chem model

    International Nuclear Information System (INIS)

    Wang, Long; Wang, Shuxiao; Zhang, Lei; Wang, Yuxuan; Zhang, Yanxu; Nielsen, Chris; McElroy, Michael B.; Hao, Jiming

    2014-01-01

    China is the largest atmospheric mercury (Hg) emitter in the world. Its Hg emissions and environmental impacts need to be evaluated. In this study, China's Hg emission inventory is updated to 2007 and applied in the GEOS-Chem model to simulate the Hg concentrations and depositions in China. Results indicate that simulations agree well with observed background Hg concentrations. The anthropogenic sources contributed 35–50% of THg concentration and 50–70% of total deposition in polluted regions. Sensitivity analysis was performed to assess the impacts of mercury emissions from power plants, non-ferrous metal smelters and cement plants. It is found that power plants are the most important emission sources in the North China, the Yangtze River Delta (YRD) and the Pearl River Delta (PRD) while the contribution of non-ferrous metal smelters is most significant in the Southwest China. The impacts of cement plants are significant in the YRD, PRD and Central China. - Highlights: • China's anthropogenic mercury emission was 643.1 t in 2007. • GEOS-Chem model well reproduces the background Hg concentrations. • Anthropogenic emissions contribute 35–50% of Hg concentrations in polluted regions. • The priorities for mercury control in polluted regions are identified. - Anthropogenic Hg emissions are updated and their impacts on atmospheric mercury concentrations and depositions are quantified for China

  7. Model analyses of atmospheric mercury: present air quality and effects of transpacific transport on the United States

    Science.gov (United States)

    Lei, H.; Liang, X.-Z.; Wuebbles, D. J.; Tao, Z.

    2013-11-01

    Atmospheric mercury is a toxic air and water pollutant that is of significant concern because of its effects on human health and ecosystems. A mechanistic representation of the atmospheric mercury cycle is developed for the state-of-the-art global climate-chemistry model, CAM-Chem (Community Atmospheric Model with Chemistry). The model simulates the emission, transport, transformation and deposition of atmospheric mercury (Hg) in three forms: elemental mercury (Hg(0)), reactive mercury (Hg(II)), and particulate mercury (PHg). Emissions of mercury include those from human, land, ocean, biomass burning and volcano related sources. Land emissions are calculated based on surface solar radiation flux and skin temperature. A simplified air-sea mercury exchange scheme is used to calculate emissions from the oceans. The chemistry mechanism includes the oxidation of Hg(0) in gaseous phase by ozone with temperature dependence, OH, H2O2 and chlorine. Aqueous chemistry includes both oxidation and reduction of Hg(0). Transport and deposition of mercury species are calculated through adapting the original formulations in CAM-Chem. The CAM-Chem model with mercury is driven by present meteorology to simulate the present mercury air quality during the 1999-2001 period. The resulting surface concentrations of total gaseous mercury (TGM) are then compared with the observations from worldwide sites. Simulated wet depositions of mercury over the continental United States are compared to the observations from 26 Mercury Deposition Network stations to test the wet deposition simulations. The evaluations of gaseous concentrations and wet deposition confirm a strong capability for the CAM-Chem mercury mechanism to simulate the atmospheric mercury cycle. The general reproduction of global TGM concentrations and the overestimation on South Africa indicate that model simulations of TGM are seriously affected by emissions. The comparison to wet deposition indicates that wet deposition patterns

  8. Sedimentary mercury (Hg) in the marginal seas adjacent to Chinese high-Hg emissions: Source-to-sink, mass inventory, and accumulation history.

    Science.gov (United States)

    Kim, Jihun; Lim, Dhongil; Jung, Dohyun; Kang, Jeongwon; Jung, Hoisoo; Woo, Hanjun; Jeong, Kapsik; Xu, Zhaokai

    2018-03-01

    We comprehensively investigated sedimentary Hg in Yellow and East China Seas (YECSs), which constitute potentially important depocenters for large anthropogenic Hg emissions from mainland China. A large dataset of Al-TOC-Hg concentrations led to an in-depth understanding of sedimentary Hg in the entire YECSs, including distribution and its determinants, source-to-sink, background levels, inventory in flux and budget, and accumulation history. Especially, the net atmospheric Hg flux to the sediments was estimated to be 1.3 × 10 -5  g/m 2 /yr, which corresponded reasonably well to that calculated using a box model. About 21.2 tons of atmospheric Hg (approximately 4% of the total anthropogenic atmospheric Hg emissions from China) were buried annually in the YECS basin. This result implies that most of atmospheric Hg from China is transferred to the surface of the Pacific (including the East/Japan Sea and South China Sea) by the westerlies and, consequently, can play a critical role in open-sea aquatic ecosystems. Copyright © 2018 Elsevier Ltd. All rights reserved.

  9. Observed decrease in atmospheric mercury explained by global decline in anthropogenic emissions

    Science.gov (United States)

    Yanxu Zhang,; Daniel J. Jacob,; Hannah M. Horowitz,; Long Chen,; Helen M. Amos,; Krabbenhoft, David P.; Franz Slemr,; Vincent L. St. Louis,; Elsie M. Sunderland,

    2015-01-01

    Observations of elemental mercury (Hg0) at sites in North America and Europe show large decreases (∼1–2% y−1) from 1990 to present. Observations in background northern hemisphere air, including Mauna Loa Observatory (Hawaii) and CARIBIC (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container) aircraft flights, show weaker decreases (Asia. Implementation of our inventory in a global 3D atmospheric Hg simulation [GEOS-Chem (Goddard Earth Observing System-Chemistry)] coupled to land and ocean reservoirs reproduces the observed large-scale trends in atmospheric Hg0 concentrations and in HgII wet deposition. The large trends observed in North America and Europe reflect the phase-out of Hg from commercial products as well as the cobenefit from SO2 and NOx emission controls on coal-fired utilities.

  10. Total dissolved atmospheric nitrogen deposition in the anoxic Cariaco basin

    Science.gov (United States)

    Rasse, R.; Pérez, T.; Giuliante, A.; Donoso, L.

    2018-04-01

    Atmospheric deposition of total dissolved nitrogen (TDN) is an important source of nitrogen for ocean primary productivity that has increased since the industrial revolution. Thus, understanding its role in the ocean nitrogen cycle will help assess recent changes in ocean biogeochemistry. In the anoxic Cariaco basin, the place of the CARIACO Ocean Time-Series Program, the influence of atmospherically-deposited TDN on marine biogeochemistry is unknown. In this study, we measured atmospheric TDN concentrations as dissolved organic (DON) and inorganic (DIN) nitrogen (TDN = DIN + DON) in atmospheric suspended particles and wet deposition samples at the northeast of the basin during periods of the wet (August-September 2008) and dry (March-April 2009) seasons. We evaluated the potential anthropogenic N influences by measuring wind velocity and direction, size-fractionated suspended particles, chemical traces and by performing back trajectories. We found DIN and DON concentration values that ranged between 0.11 and 0.58 μg-N m-3 and 0.11-0.56 μg-N m-3 in total suspended particles samples and between 0.08 and 0.54 mg-N l-1 and 0.02-1.3 mg-N l-1 in wet deposition samples, respectively. Continental air masses increased DON and DIN concentrations in atmospheric suspended particles during the wet season. We estimate an annual TDN atmospheric deposition (wet + particles) of 3.6 × 103 ton-N year-1 and concluded that: 1) Atmospheric supply of TDN plays a key role in the C and N budget of the basin because replaces a fraction of the C (20% by induced primary production) and N (40%) removed by sediment burial, 2) present anthropogenic N could contribute to 30% of TDN atmospheric deposition in the basin, and 3) reduced DON (gas + particles) should be a significant component of bulk N deposition.

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

    International Nuclear Information System (INIS)

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

    2015-01-01

    Characterization of air pollutant deposition resulting from Athabasca oil sands development is necessary to assess risk to humans and the environment. To investigate this we collected event-based wet deposition during a pilot study in 2010–2012 at the AMS 6 site 30 km from the nearest upgrading facility in Fort McMurray, AB, Canada. Sulfate, nitrate and ammonium deposition was (kg/ha) 1.96, 1.60 and 1.03, respectively. Trace element pollutant deposition ranged from 2 × 10"−"5 - 0.79 and exhibited the trend Hg < Se < As < Cd < Pb < Cu < Zn < S. Crustal element deposition ranged from 1.4 × 10"−"4 – 0.46 and had the trend: La < Ce < Sr < Mn < Al < Fe < Mg. S, Se and Hg demonstrated highest median enrichment factors (130–2020) suggesting emissions from oil sands development, urban activities and forest fires were deposited. High deposition of the elements Sr, Mn, Fe and Mg which are tracers for soil and crustal dust implies land-clearing, mining and hauling emissions greatly impacted surrounding human settlements and ecosystems. - Highlights: • Atmospheric event wet deposition was collected during a 21 month pilot study. • Major ion, anthropogenic and crustal element wet deposition was characterized. • Low precipitation depths attenuated major ion and anthropogenic element deposition. • Oil sands development, urban activities and forest fires contributed to deposition. - In the vicinity of oil sands, monitoring revealed that wet deposition of major ions (SO_4"2"−, NO_3"-, NH_4"+) was highest followed by S and Mg, the latter is a tracer for soil/crustal dust.

  12. Wet deposition of mercury in Qingdao, a coastal urban city in China: Concentrations, fluxes, and influencing factors

    Science.gov (United States)

    Chen, Lufeng; Li, Yanbin; Liu, Chang; Guo, Lina; Wang, Xiulin

    2018-02-01

    Mercury (Hg) is a global pollutant of public concern because of its high toxicity and capability for worldwide distribution via long-range atmospheric transportation. Wet atmospheric deposition is an important source of Hg in both terrestrial and aquatic environments. Concentrations of various Hg species in precipitation were monitored from March 2016 to February 2017 in a coastal urban area of Qingdao, and their wet deposition fluxes were estimated. The results showed that the volume-weighted mean (VWM) concentrations of total mercury (THg), reactive mercury (RHg), dissolved THg (DTHg), particulate THg (PTHg), total methylmercury (TMeHg), and dissolved and particulate MeHg (DMeHg and PMeHg) in Qingdao's precipitation were 13.6, 1.5, 5.4, 8.2, 0.38, 0.15, and 0.22 ng L-1, respectively, and their annual deposition fluxes were estimated to be 5703.0 (THg), 666.6 (RHg), 2304.0 (DTHg), 3470.4 (PTHg), 161.6 (TMeHg), 64.0 (DMeHg), and 95.7 (PMeHg) ng m-2 y-1, respectively. A relatively high proportion of MeHg in THg was observed in precipitation (3.0 ± 2.6%) possibly due to higher methylation and contributions from an oceanic source to MeHg in the precipitation. Obvious seasonal variations in Hg concentrations and deposition fluxes were observed in the precipitation in Qingdao. Correlation analyses and multiple regression analyses showed that SO2, pH, and NO3- were the controlling factors for THg in precipitation, whereas the MeHg concentration was primarily controlled by the SO2, WS, Cl-, and THg concentrations. PM2.5 and Cl- were the major controlling factors for PMeHg/TMeHg, whereas the TMeHg/THg ratio was mainly influenced by Cl-. The THg and MeHg fluxes were primarily controlled by precipitation, whereas Cl- was also an important factor for the MeHg wet deposition flux. The results of a 72-h backward trajectory analysis in the study region with the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model indicated that Hg deposition in Qingdao mainly

  13. Global atmospheric model for mercury including oxidation by bromine atoms

    Directory of Open Access Journals (Sweden)

    C. D. Holmes

    2010-12-01

    Full Text Available Global models of atmospheric mercury generally assume that gas-phase OH and ozone are the main oxidants converting Hg0 to HgII and thus driving mercury deposition to ecosystems. However, thermodynamic considerations argue against the importance of these reactions. We demonstrate here the viability of atomic bromine (Br as an alternative Hg0 oxidant. We conduct a global 3-D simulation with the GEOS-Chem model assuming gas-phase Br to be the sole Hg0 oxidant (Hg + Br model and compare to the previous version of the model with OH and ozone as the sole oxidants (Hg + OH/O3 model. We specify global 3-D Br concentration fields based on our best understanding of tropospheric and stratospheric Br chemistry. In both the Hg + Br and Hg + OH/O3 models, we add an aqueous photochemical reduction of HgII in cloud to impose a tropospheric lifetime for mercury of 6.5 months against deposition, as needed to reconcile observed total gaseous mercury (TGM concentrations with current estimates of anthropogenic emissions. This added reduction would not be necessary in the Hg + Br model if we adjusted the Br oxidation kinetics downward within their range of uncertainty. We find that the Hg + Br and Hg + OH/O3 models are equally capable of reproducing the spatial distribution of TGM and its seasonal cycle at northern mid-latitudes. The Hg + Br model shows a steeper decline of TGM concentrations from the tropics to southern mid-latitudes. Only the Hg + Br model can reproduce the springtime depletion and summer rebound of TGM observed at polar sites; the snowpack component of GEOS-Chem suggests that 40% of HgII deposited to snow in the Arctic is transferred to the ocean and land reservoirs, amounting to a net deposition flux to the Arctic of 60 Mg a−1. Summertime events of depleted Hg0 at Antarctic sites due to subsidence are much better simulated by

  14. Accumulation of Mercury (Hg) and Methyl Mercury (Me Hg) Concentrations In Selected Marine Biota From Manjung Coastal Area

    International Nuclear Information System (INIS)

    Anisa Abdullah; Zaini Hamzah; Ahmad Saat; Ahmad Saat; Abd Khalik Wood; Masitah Alias

    2015-01-01

    Level of mercury (Hg) and methyl mercury (Me Hg) in marine ecosystem has been intensively studied as these toxic substances could be accumulated in the marine biota. This study is focusing on the Hg and Me Hg content in marine biota in Manjung coastal area. This area has high potential being affected by rapid socio-economic development of Manjung area such as heavy industrial activities (coal fired power plant, iron foundries, port development and factories), agricultural runoff, waste and toxic discharge, quarries, housing constructions. It may has a potential risk when released into the atmosphere and dispersed on the surface of water and continue deposited at the bottom of the water and sediment and being absorbed by marine biota. The concentrations of Hg and Me Hg in marine ecosystem can be adversely affect human health when it enters the food chain. In this study, five species of marine biota including Johnius dussumieri (Ikan Gelama), Pseudorhombus malayanus (Ikan Sebelah), Arius maculatus (Ikan Duri), Portunus pelagicus (Ketam Renjong) and Charybdis natator (Ketam Salib) were collected during rainy and dry seasons. Measurements were carried out using inductively coupled plasma mass spectrometry (ICP-MS) technique. The Hg concentrations for dry and rainy season are in the range 65.13-102.12 μg/ kg and 75.75-106.10 μg/ kg respectively, while for MeHg concentrations for dry and rainy seasons are in the range 4.35-6.26 μg/ kg and 5.42-6.46 μg/ kg, respectively. These results are below the limit set by Malaysia Food Act (1983). Generally, marine biota from the Manjung coastal area is safe to consume due to low value of ingestion dose rate and health risk index (HRI) for human health. (author)

  15. Multielement atmospheric deposition study in Croatia using moss biomonitoring, NAA, AAS and GIS technologies

    International Nuclear Information System (INIS)

    Spiric, Z.; Frontas'eva, M.V.; Gundorina, S.F.; Ostrovnaya, T.M.; Stafilov, T.; Enimiteva, V.; Steinnes, E.; Bukovec, D.

    2009-01-01

    For the first time the moss biomonitoring technique and two complementary analytical techniques - neutron activation analysis (NAA) and atomic absorption spectrometry (AAS) - were applied to study multielement atmospheric deposition in the Republic of Croatia. Moss samples were collected during the summer 2006 from 98 sites evenly distributed over the country. Sampling was performed in accordance with the LRTAP Convention - ICP Vegetation protocol and sampling strategy of the European Programme on Biomonitoring of Heavy Metal Atmospheric Deposition. Conventional and epithermal neutron activation analyses made it possible to determine concentrations of 41 elements including key heavy metals such as Pb, Cd, Hg, and Cu determined by AAS. Principal component analysis (factor analysis with VARIMAX rotation) was applied to distinguish elements mainly of anthropogenic origin from those predominantly originating from natural sources. Geographical distribution maps of the elements over the sampled territory were constructed using GIS technology. The median values for Croatia are consistent with the corresponding values for all Europe for most elements. It was shown that the Adriatic coastline of Croatia may be considered as an environmentally pristine area. This study was conducted for providing reliable assessment of air quality throughout Croatia and producing information needed for better identification of pollution sources and improving the potential for assessing environmental and health risks in Croatia associated with toxic metals

  16. Atmospheric heavy metal deposition accumulated in rural forest soils of southern Scandinavia

    DEFF Research Database (Denmark)

    Hovmand, Mads Frederik; Kemp, Kaare; Kystol, J.

    2008-01-01

    Thirty-three years of measurements of atmospheric heavy metal (HM) deposition (bulk precipitation) in Denmark combined with European emission inventories form the basis for calculating a 50-year accumulated atmospheric input to a remote forest plantation on the island of Laesoe. Soil samples taken...... in atmospheric deposition and in soils. The accumulated atmospheric deposition is of the same magnitude as the increase of these metals in the top soil....

  17. Effects of historical and modern mining on mercury deposition in southeastern Peru.

    Science.gov (United States)

    Beal, Samuel A; Jackson, Brian P; Kelly, Meredith A; Stroup, Justin S; Landis, Joshua D

    2013-11-19

    Both modern anthropogenic emissions of mercury (Hg), primarily from artisanal and small-scale gold mining (ASGM), and preindustrial anthropogenic emissions from mining are thought to have a large impact on present-day atmospheric Hg deposition. We study the spatial distribution of Hg and its depositional history over the past ∼400 years in sediment cores from lakes located regionally proximal (∼90-150 km) to the largest ASGM in Peru and distal (>400 km) to major preindustrial mining centers. Total Hg concentrations in surface sediments from fourteen lakes are typical of remote regions (10-115 ng g(-1)). Hg fluxes in cores from four lakes demonstrate preindustrial Hg deposition in southeastern Peru was spatially variable and at least an order of magnitude lower than previously reported fluxes in lakes located closer to mining centers. Average modern (A.D. 2000-2011) Hg fluxes in these cores are 3.4-6.9 μg m(-2) a(-1), compared to average preindustrial (A.D. 1800-1850) fluxes of 0.8-2.5 μg m(-2) a(-1). Modern Hg fluxes determined from the four lakes are on average 3.3 (±1.5) times greater than their preindustrial fluxes, similar to those determined in other remote lakes around the world. This agreement suggests that Hg emissions from ASGM are likely not significantly deposited in nearby down-wind regions.

  18. Atmospheric Deposition of Phosphorus to the Everglades: Concepts, Constraints, and Published Deposition Rates for Ecosystem Management

    Directory of Open Access Journals (Sweden)

    Garth W. Redfield

    2002-01-01

    Full Text Available This paper summarizes concepts underlying the atmospheric input of phosphorus (P to ecosystems, published rates of P deposition, measurement methods, and approaches to future monitoring and research. P conveyed through the atmosphere can be a significant nutrient source for some freshwater and marine ecosystems. Particle sources and sinks at the land-air interface produce variation in P deposition from the atmosphere across temporal and spatial scales. Natural plant canopies can affect deposition rates by changing the physical environment and surface area for particle deposition. Land-use patterns can alter P deposition rates by changing particle concentrations in the atmosphere. The vast majority of P in dry atmospheric deposition is conveyed by coarse (2.5 to 10 μm and giant (10 to 100 μm particles, and yet these size fractions represent a challenge for long-term atmospheric monitoring in the absence of accepted methods for routine sampling. Most information on P deposition is from bulk precipitation collectors and wet/dry bucket sampling, both with questionable precision and accuracy. Most published annual rates of P deposition are gross estimates derived from bulk precipitation sampling in locations around the globe and range from about 5 to well over 100 mg P m–2 year–1, although most inland ecosystems receive between 20 and 80 mg P m–2 year–1. Rates below 30 mg P m–2 year–1 are found in remote areas and near coastlines. Intermediate rates of 30 to 50 mg P m–2 year–1 are associated with forests or mixed land use, and rates of 50 to 100 mg P m–2 year–1 or more are often recorded from urban or agricultural settings. Comparison with other methods suggests that these bulk precipitation estimates provide crude boundaries around actual P deposition rates for various land uses. However, data screening cannot remove all positive bias caused by contamination of bucket or bulk collectors. As a consequence, continued sampling

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

    Science.gov (United States)

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

    2012-04-01

    Mercury (Hg) is emitted in the atmosphere by anthropogenic and natural sources, these last accounting for one third of the total emissions. Since the pre-industrial age, the atmospheric deposition of mercury have increased notably, while ocean emissions have doubled owing to the re-emission of anthropogenic mercury. Exchange between the atmosphere and ocean plays an important role in cycling and transport of mercury. We present the preliminary results from a study on the distribution and evasion flux of mercury at the atmosphere/sea interface in the Augusta basin (SE Sicily, southern Italy), a semi-enclosed marine area affected by a high degree of contamination (heavy metals and PHA) due to the oil refineries placed inside its commercial harbor. It seems that the intense industrial activity of the past have lead to an high Hg pollution in the bottom sediments of the basin, whose concentrations are far from the background mercury value found in most of the Sicily Strait sediments. The release of mercury into the harbor seawater and its dispersion by diffusion from sediments to the surface, make the Augusta basin a potential supplier of mercury both to the Mediterranean Sea and the atmosphere. Based on these considerations, mercury concentration and flux at the air-sea interface of the Bay have been estimated using a real-time atomic adsorption spectrometer (LUMEX - RA915+) and an home-made accumulation chamber, respectively. Estimated Total Atmospheric Mercury (TGM) concentrations during the cruise on the bay were in the range of 1-3 ng · m-3, with a mean value of about 1.4 ng · m-3. These data well fit with the background Hgatm concentration values detected on the land (1-2 ng · m-3, this work), and, more in general, with the background atmospheric TGM levels found in the North Hemisphere (1.5-1.7 ng · m-3)a. Besides, our measurements are in the range of those reported for other important polluted marine areas. The mercury evasion flux at the air-sea interface

  20. Sulfur accumulation and atmospherically deposited sulfate in the Lake States.

    Science.gov (United States)

    Mark B. David; George Z. Gernter; David F. Grigal; Lewis F. Ohmann

    1989-01-01

    Characterizes the mass of soil sulfur (adjusted for nitrogen), and atmospherically deposited sulfate along an acid precipitation gradient from Minnesota to Michigan. The relationship of these variables, presented graphically through contour mapping, suggests that patterns of atmospheric wet sulfate deposition are reflected in soil sulfur pools.

  1. Direct and indirect atmospheric deposition of PCBs to the Delaware River watershed.

    Science.gov (United States)

    Totten, Lisa A; Panangadan, Maya; Eisenreich, Steven J; Cavallo, Gregory J; Fikslin, Thomas J

    2006-04-01

    Atmospheric deposition can be an important source of PCBs to aquatic ecosystems. To develop the total maximum daily load (TMDL) for polychlorinated biphenyls (PCBs) for the tidal Delaware River (water-quality Zones 2-5), estimates of the loading of PCBs to the river from atmospheric deposition were generated from seven air-monitoring sites along the river. This paper presents the atmospheric PCB data from these sites, estimates direct atmospheric deposition fluxes, and assesses the importance of atmospheric deposition relative to other sources of PCBs to the river. Also, the relationship between indirect atmospheric deposition and PCB loads from minor tributaries to the Delaware River is discussed. Data from these sites revealed high atmospheric PCB concentrations in the Philadelphia/Camden urban area and lower regional background concentrations in the more remote areas. Wet, dry particle, and gaseous absorption deposition are estimated to contribute about 0.6, 1.8, and 6.5 kg year-(-1) sigmaPCBs to the River, respectively, exceeding the TMDL of 0.139 kg year(-1) by more than an order of magnitude. Penta-PCB watershed fluxes were obtained by dividing the tributary loads by the watershed area. The lowest of these watershed fluxes are less than approximately 1 ng m(-2) day(-1) for penta-PCB and probably indicates pristine watersheds in which PCB loads are dominated by atmospheric deposition. In these watersheds, the pass-through efficiency of PCBs is estimated to be on the order of 1%.

  2. Atmospheric heavy metal deposition in Europe estimated by moss analysis

    Energy Technology Data Exchange (ETDEWEB)

    Ruehling, Aa. [Swedish Environmental Research Inst., Lund (Sweden). Dept. of Ecology

    1995-12-31

    Atmospheric heavy metal deposition in Europe including 21 countries was monitored in 1990-1992 by the moss technique. This technique is based on the fact that the concentrations of heavy metals in moss are closely correlated to atmospheric deposition. This was the first attempt to map heavy metal deposition in this large area. The objectives of the project were to characterise qualitatively and quantitatively the regional atmospheric deposition pattern of heavy metals in background areas in Europe, to indicate the location of important heavy metal pollution sources and to allow retrospective comparisons with similar studies. The present survey is a follow-up of a joint Danish and Swedish project in 1980 and an extended survey in 1985 within the framework of the Nordic Council of Ministers. In Sweden, heavy-metal deposition was first mapped on a nation-wide scale in 1968-1971 and 1975. (author)

  3. Atmospheric heavy metal deposition in Europe estimated by moss analysis

    Energy Technology Data Exchange (ETDEWEB)

    Ruehling, Aa [Swedish Environmental Research Inst., Lund (Sweden). Dept. of Ecology

    1996-12-31

    Atmospheric heavy metal deposition in Europe including 21 countries was monitored in 1990-1992 by the moss technique. This technique is based on the fact that the concentrations of heavy metals in moss are closely correlated to atmospheric deposition. This was the first attempt to map heavy metal deposition in this large area. The objectives of the project were to characterise qualitatively and quantitatively the regional atmospheric deposition pattern of heavy metals in background areas in Europe, to indicate the location of important heavy metal pollution sources and to allow retrospective comparisons with similar studies. The present survey is a follow-up of a joint Danish and Swedish project in 1980 and an extended survey in 1985 within the framework of the Nordic Council of Ministers. In Sweden, heavy-metal deposition was first mapped on a nation-wide scale in 1968-1971 and 1975. (author)

  4. A Distinct Magnetic Isotope Effect Measured in Atmospheric Mercury in Epiphytes

    Science.gov (United States)

    Ghosh, S.; Odom, A. L.

    2007-12-01

    Due to the importance of Mercury as an environmental contaminant, mercury cycling in the atmosphere has been extensively studied. However, there still remain uncertainties in the relative amounts of natural and anthropogenic emissions, atmospheric deposition rates as well as the spatial variation of atmospheric mercury. Part of a study to determine the isotopic composition of mercury deposited from the atmosphere has involved the use of epiphytes as monitors. The greatest advantage of such natural monitors is that a widespread, high-density network is possible at low cost. One of the disadvantages at present is that these monitors likely contain different mercury species (for example both gaseous, elemental mercury trapped by adsorption and Hg (II) by wet deposition). The project began with the understanding that biochemical reactions involving metallothioneins within the epiphytes might have produced an isotopic effect. One such regional network was composed of samples of Tillandsia usenoides (common name: Spanish moss) collected along the eastern Coastal Plain of the U.S. from northern Florida to North Carolina. The isotopic composition of a sample is expressed as permil deviations from a standard. The deviations are defined as δAHg = \\left(\\frac{Rsample}{Rstd}-1 \\right)1000 ‰ , where A represents the atomic mass number. R=\\frac{AHg}{202Hg} were measured for the isotopes 198Hg, 199Hg, 200Hg, 201Hg, 202Hg and 204Hg relative to the mercury standard SRM NIST 3133, by a standard-sample bracketing technique. For all samples, the delta values of the even-N plotted against atomic mass numbers define a linear curve. For the odd-N isotopes, δ199Hg and δ201Hg deviate from this mass-dependent fractionation (MDF) relationship and indicate a mass-independent fractionation (MIF) effect and a negative anomaly, i.e. a depletion in 199Hg and 201Hg relative to the even-N isotopes. These deviations are expressed as Δ199Hg = δ199Hgtotal - δ199HgMDF. A Δ201Hg/Δ199Hg

  5. Ecological geochemical assessment and source identification of trace elements in atmospheric deposition of an emerging industrial area: Beibu Gulf economic zone.

    Science.gov (United States)

    Zhong, Cong; Yang, Zhongfang; Jiang, Wei; Hu, Baoqing; Hou, Qingye; Yu, Tao; Li, Jie

    2016-12-15

    Industrialization and urbanization have led to a deterioration in air quality and provoked some serious environmental concerns. Fifty-four samples of atmospheric deposition were collected from an emerging industrial area and analyzed to determine the concentrations of 11 trace elements (As, Cd, Cu, Fe, Hg, Mn, Mo, Pb, Se, S and Zn). Multivariate geostatistical analyses were conducted to determine the spatial distribution, possible sources and enrichment degrees of trace elements in atmospheric deposition. Results indicate that As, Fe and Mo mainly originated from soil, their natural parent materials, while the remaining trace elements were strongly influenced by anthropogenic or natural activities, such as coal combustion in coal-fired power plants (Pb, Se and S), manganese ore (Mn, Cd and Hg) and metal smelting (Cu and Zn). The results of ecological geochemical assessment indicate that Cd, Pb and Zn are the elements of priority concern, followed by Mn and Cu, and other heavy metals, which represent little threat to local environment. It was determine that the resuspension of soil particles impacted the behavior of heavy metals by 55.3%; the impact of the coal-fired power plants was 18.9%; and the contribution of the local manganese industry was 9.6%. The comparison of consequences from various statistical methods (principal component analysis (PCA), cluster analysis (CA), enrichment factor (EF) and absolute principle component score (APCS)-multiple linear regression (MLR)) confirmed the credibility of this research. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Global observations and modeling of atmosphere-surface exchange of elemental mercury: a critical review

    Science.gov (United States)

    Zhu, Wei; Lin, Che-Jen; Wang, Xun; Sommar, Jonas; Fu, Xuewu; Feng, Xinbin

    2016-04-01

    Reliable quantification of air-surface fluxes of elemental Hg vapor (Hg0) is crucial for understanding mercury (Hg) global biogeochemical cycles. There have been extensive measurements and modeling efforts devoted to estimating the exchange fluxes between the atmosphere and various surfaces (e.g., soil, canopies, water, snow, etc.) in the past three decades. However, large uncertainties remain due to the complexity of Hg0 bidirectional exchange, limitations of flux quantification techniques and challenges in model parameterization. In this study, we provide a critical review on the state of science in the atmosphere-surface exchange of Hg0. Specifically, the advancement of flux quantification techniques, mechanisms in driving the air-surface Hg exchange and modeling efforts are presented. Due to the semi-volatile nature of Hg0 and redox transformation of Hg in environmental media, Hg deposition and evasion are influenced by multiple environmental variables including seasonality, vegetative coverage and its life cycle, temperature, light, moisture, atmospheric turbulence and the presence of reactants (e.g., O3, radicals, etc.). However, the effects of these processes on flux have not been fundamentally and quantitatively determined, which limits the accuracy of flux modeling. We compile an up-to-date global observational flux database and discuss the implication of flux data on the global Hg budget. Mean Hg0 fluxes obtained by micrometeorological measurements do not appear to be significantly greater than the fluxes measured by dynamic flux chamber methods over unpolluted surfaces (p = 0.16, one-tailed, Mann-Whitney U test). The spatiotemporal coverage of existing Hg0 flux measurements is highly heterogeneous with large data gaps existing in multiple continents (Africa, South Asia, Middle East, South America and Australia). The magnitude of the evasion flux is strongly enhanced by human activities, particularly at contaminated sites. Hg0 flux observations in East

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

    Science.gov (United States)

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

    2011-01-01

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

  8. Removal of Atmospheric Ethanol by Wet Deposition: A Global Flux Estimate

    Science.gov (United States)

    Felix, J. D. D.; Willey, J. D.; Avery, B.; Thomas, R.; Mullaugh, K.; Kieber, R. J.; Mead, R. N.; Helms, J. R.; Campos, L.; Shimizu, M. S.; Guibbina, F.

    2017-12-01

    Global ethanol fuel consumption has increased exponentially over the last two decades and the US plans to double annual renewable fuel production in the next five years as required by the renewable fuel standard. Regardless of the technology or feedstock used to produce the renewable fuel, the primary end product will be ethanol. Increasing ethanol fuel consumption will have an impact on the oxidizing capacity of the atmosphere and increase atmospheric concentrations of the secondary pollutant peroxyacetyl nitrate as well a variety of VOCs with relatively high ozone reactivities (e.g. ethanol, formaldehyde, acetaldehyde). Despite these documented effects of ethanol emissions on atmospheric chemistry, current global atmospheric ethanol budget models have large uncertainties in the magnitude of ethanol sources and sinks. The presented work investigates the global wet deposition sink by providing the first estimate of the global wet deposition flux of ethanol (2.4 ± 1.6 Tg/yr) based on empirical wet deposition data (219 samples collected at 12 locations). This suggests the wet deposition sink removes between 6 and 17% of atmospheric ethanol annually. Concentrations of ethanol in marine wet deposition (25 ± 6 nM) were an order of magnitude less than in the majority of terrestrial deposition (345 ± 280 nM). Terrestrial deposition collected in locations impacted by high local sources of biofuel usage and locations downwind from ethanol distilleries were an order of magnitude higher in ethanol concentration (3090 ± 448 nM) compared to deposition collected in terrestrial locations not impacted by these sources. These results indicate that wet deposition of ethanol is heavily influenced by local sources and ethanol emission impacts on air quality may be more significant in highly populated areas. As established and developing countries continue to rapidly increase ethanol fuel consumption and subsequent emissions, understanding the magnitude of all ethanol sources and

  9. Atmospheric metal deposition in France: Estimation based on moss analysis. First results

    International Nuclear Information System (INIS)

    Galsomies, L.; Letrouit-Galinou, M.A.; Avnaim, M.; Duclaux, G.; Deschamps, C.; Savanne, D.

    2000-01-01

    The aim of this programme set up by University Pierre and Marie Curie-Paris VI and ADEME (French Agency for the Environment and Energy Management) is to obtain information on the atmospheric deposition of 36 elements (most being heavy metals) all over France, using 5 common mosses as bioaccumulators: Pleurozium schreberi, Hylocomium splendens, Hypnum cupressiforme, Scleropodium purum and Thuidium tamariscinum. Sampling was performed in 1996 from April to November thanks to 43 collectors. One sample of moss at least has been collected in 512 sites distributed over France, with an average density of one site each 1000 km 2 . Procedures for sampling, drying, cleaning, sorting are strictly codified based on Scandinavian guidelines. Analyses are performed according to two procedures: ICP-MS (Inductively Coupled Plasma, Mass Spectrometry) for Pb, Ni specialty and INAA (instrumental Neutron Activation Analysis for other elements. Data concerning As, Cd, Cr, Cu, Fe, Hg, Pb. Ni, V, Zn will be incorporated into the 1995-1996 European Programme 'Atmospheric Heavy Metal Deposition in Europe - estimation based on moss analysis' coordinated by the Nordic Council. The analyses are in progress, but preliminary results from Ile-de-France have been achieved for 34 elements in INAA. A preliminary study has shown that interspecies calibration could be possible for some heavy metals and that saturation effects in one species could be present when the intercalibration between species is not possible. Such a programme is made possible thanks to the financial support of the French Ministry of Environment and ADEME and with the active cooperation of several national organisations, especially the Laboratory Pierre Sue (CNRS-CEA). (author)

  10. Effects of atmospheric inorganic nitrogen deposition on ocean biogeochemistry

    OpenAIRE

    Krishnamurthy, Aparna; Moore, J. Keith; Zender, Charles S; Luo, Chao

    2007-01-01

     We perform a sensitivity study with the Biogeochemical Elemental Cycling (BEC) ocean model to understand the impact of atmospheric inorganic nitrogen deposition on marine biogeochemistry and air-sea CO2 exchange. Simulations involved examining the response to three different atmospheric inorganic nitrogen deposition scenarios namely, Pre-industrial (22 Tg N/year), 1990s (39 Tg N/year), and an Intergovernmental Panel on Climate Change (IPCC) prediction for 2100, IPCC-A1FI (69 Tg N/year). Glob...

  11. Atmospheric deposition, operational report for air pollution 2003. NOVA 2003; Atmosfaerisk deposition, driftsrapport for Luftforurening i 2003 NOVA 2003

    Energy Technology Data Exchange (ETDEWEB)

    Ellermann, T.; Hertel, O.; Ambelas Skjoeth, C.; Kemp, K.; Monies, C.

    2004-12-01

    This report presents measurements and calculations from the atmospheric part of NOVA 2003 and covers results for 2003. It summarises the main results concerning concentrations and depositions of nitrogen, phosphorous and sulphur compounds related to eutrofication and acidification and selected heavy metals. Depositions of atmospheric compounds to Danish marine waters as well as land surface are presented. The measurements in the monitoring programme are supplemented with model calculations of concentrations and depositions of nitrogen and sulphur compounds to Danish land surfaces as well as marine waters, fjords and bays using the ACDEP model (Atmospheric Chemistry and Deposition). The model is a so-called trajectory model and simulates the physical and chemical processes in the atmosphere using meteorological and emission data input. (BA)

  12. Atmospheric transport, diffusion, and deposition of radioactivity

    International Nuclear Information System (INIS)

    Crawford, T.V.

    1969-01-01

    From a meteorological standpoint there are two types of initial sources for atmospheric diffusion from Plowshare applications. One is the continuous point-source plume - a slow, small leak from an underground engineering application. The other is the large cloud produced almost instantaneously from a cratering application. For the purposes of this paper the effluent from neither type has significant fall speed. Both are carried by the prevailing wind, but the statistics of diffusion for each type are different. The use of constant altitude, isobaric and isentropic techniques for predicting the mean path of the effluent is briefly discussed. Limited data are used to assess the accuracy of current trajectory forecast techniques. Diffusion of continuous point-source plumes has been widely studied; only a brief review is given of the technique used and the variability of their results with wind speed and atmospheric stability. A numerical model is presented for computing the diffusion of the 'instantaneously-produced' large clouds. This model accounts for vertical and diurnal changes in atmospheric turbulence, wet and dry deposition, and radioactivity decay. Airborne concentrations, cloud size, and deposition on the ground are calculated. Pre- and post-shot calculations of cloud center, ground level concentration of gross radioactivity, and dry and wet deposition of iodine-131 are compared with measurements on Cabriolet and Buggy. (author)

  13. Atmospheric transport, diffusion, and deposition of radioactivity

    Energy Technology Data Exchange (ETDEWEB)

    Crawford, T V [Lawrence Radiation Laboratory, Livermore, CA (United States)

    1969-07-01

    From a meteorological standpoint there are two types of initial sources for atmospheric diffusion from Plowshare applications. One is the continuous point-source plume - a slow, small leak from an underground engineering application. The other is the large cloud produced almost instantaneously from a cratering application. For the purposes of this paper the effluent from neither type has significant fall speed. Both are carried by the prevailing wind, but the statistics of diffusion for each type are different. The use of constant altitude, isobaric and isentropic techniques for predicting the mean path of the effluent is briefly discussed. Limited data are used to assess the accuracy of current trajectory forecast techniques. Diffusion of continuous point-source plumes has been widely studied; only a brief review is given of the technique used and the variability of their results with wind speed and atmospheric stability. A numerical model is presented for computing the diffusion of the 'instantaneously-produced' large clouds. This model accounts for vertical and diurnal changes in atmospheric turbulence, wet and dry deposition, and radioactivity decay. Airborne concentrations, cloud size, and deposition on the ground are calculated. Pre- and post-shot calculations of cloud center, ground level concentration of gross radioactivity, and dry and wet deposition of iodine-131 are compared with measurements on Cabriolet and Buggy. (author)

  14. Deposition rates of viruses and bacteria above the atmospheric boundary layer.

    Science.gov (United States)

    Reche, Isabel; D'Orta, Gaetano; Mladenov, Natalie; Winget, Danielle M; Suttle, Curtis A

    2018-04-01

    Aerosolization of soil-dust and organic aggregates in sea spray facilitates the long-range transport of bacteria, and likely viruses across the free atmosphere. Although long-distance transport occurs, there are many uncertainties associated with their deposition rates. Here, we demonstrate that even in pristine environments, above the atmospheric boundary layer, the downward flux of viruses ranged from 0.26 × 10 9 to >7 × 10 9  m -2 per day. These deposition rates were 9-461 times greater than the rates for bacteria, which ranged from 0.3 × 10 7 to >8 × 10 7  m -2 per day. The highest relative deposition rates for viruses were associated with atmospheric transport from marine rather than terrestrial sources. Deposition rates of bacteria were significantly higher during rain events and Saharan dust intrusions, whereas, rainfall did not significantly influence virus deposition. Virus deposition rates were positively correlated with organic aerosols 0.7 μm, implying that viruses could have longer residence times in the atmosphere and, consequently, will be dispersed further. These results provide an explanation for enigmatic observations that viruses with very high genetic identity can be found in very distant and different environments.

  15. Soil as an archive of coal-fired power plant mercury deposition.

    Science.gov (United States)

    Rodríguez Martín, José Antonio; Nanos, Nikos

    2016-05-05

    Mercury pollution is a global environmental problem that has serious implications for human health. One of the most important sources of anthropogenic mercury emissions are coal-burning power plants. Hg accumulations in soil are associated with their atmospheric deposition. Our study provides the first assessment of soil Hg on the entire Spanish surface obtained from one sampling protocol. Hg spatial distribution was analysed with topsoil samples taken from 4000 locations in a regular sampling grid. The other aim was to use geostatistical techniques to verify the extent of soil contamination by Hg and to evaluate presumed Hg enrichment near the seven Spanish power plants with installed capacity above 1000 MW. The Hg concentration in Spanish soil fell within the range of 1-7564 μg kg(-1) (mean 67.2) and 50% of the samples had a concentration below 37 μg kg(-1). Evidence for human activity was found near all the coal-fired power plants, which reflects that metals have accumulated in the basin over many years. Values over 1000 μg kg(-1) have been found in soils in the vicinity of the Aboño, Soto de Ribera and Castellon power plants. However, soil Hg enrichment was detectable only close to the emission source, within an approximate range of only 15 km from the power plants. We associated this effect with airborne emissions and subsequent depositions as the potential distance through fly ash deposition. Hg associated with particles of ash tends to be deposited near coal combustion sources. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Critical levels of atmospheric pollution: criteria and concepts for operational modelling of mercury in forest and lake ecosystems

    NARCIS (Netherlands)

    Meili, M.; Bishop, K.; Bringmark, L.; Johansson, K.; Munthe, J.; Sverdrup, H.; Vries, de W.

    2003-01-01

    Mercury (Hg) is regarded as a major environmental concern in many regions, traditionally because of high concentrations in freshwater fish, and now also because of potential toxic effects on soil microflora. The predominant source of Hg in most watersheds is atmospheric deposition, which has

  17. Deposition of atmospheric 210Pb and total beta activity in Finland

    International Nuclear Information System (INIS)

    Jussi Paatero; Murat Buyukay; Juha Hatakka; Kaisa Vaaramaa; Jukka Lehto

    2015-01-01

    The seasonal and regional variation of the atmospheric 210 Pb deposition in Finland was studied. The 210 Pb activity concentration in precipitation shows a decreasing trend from southeastern Finland north-westwards. An average deposition of 40 Bq/m 2 during a 12 months period was observed. The deposition of 210 Pb shows a seasonal variation with minimum in spring and maximum in autumn and winter. The specific activity of 210 Pb (activity of 210 Pb per unit mass of stable lead) in the atmosphere has returned to the level prior to World War II owing to the reduced lead emissions into the atmosphere. (author)

  18. Spatial variation in the flux of atmospheric deposition and its ecological effects in arid Asia

    Science.gov (United States)

    Jiao, Linlin; Wang, Xunming; Li, Danfeng

    2018-06-01

    Atmospheric deposition is one of the key land surface processes, and plays important roles in regional ecosystems and global climate change. Previous studies have focused on the magnitude of and the temporal and spatial variations in the flux of atmospheric deposition, and the composition of atmospheric deposition on a local scale. However, there have been no comprehensive studies of atmospheric deposition on a regional scale and its ecological effects in arid Asia. The temporal and spatial patterns, composition of atmospheric deposition, and its potential effects on regional ecosystems in arid Asia are investigated in this study. The results show that the annual deposition flux is high on the Turan Plain, Aral Sea Desert, and Tarim Basin. The seasonal deposition flux also varies remarkably among different regions. The Tarim Basin shows higher deposition flux in both spring and summer, southern Mongolian Plateau has a higher deposition flux in spring, and the deposition flux of Iran Plateau is higher in summer. Multiple sources of elements in deposited particles are identified. Calcium, iron, aluminum, and magnesium are mainly derived from remote regions, while zinc, copper and lead have predominantly anthropogenic sources. Atmospheric deposition can provide abundant nutrients to vegetation and consequently play a role in the succession of regional ecosystems by affecting the structure, function, diversity, and primary production of the vegetation, especially the exotic or short-lived opportunistic species in arid Asia. Nevertheless, there is not much evidence of the ecological effects of atmospheric deposition on the regional and local scale. The present results may help in further understanding the mechanism of atmospheric deposition as well as providing a motivation for the protection of the ecological environment in arid Asia.

  19. The annual averaged atmospheric dispersion factor and deposition factor according to methods of atmospheric stability classification

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Hae Sun; Jeong, Hyo Joon; Kim, Eun Han; Han, Moon Hee; Hwang, Won Tae [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-09-15

    This study analyzes the differences in the annual averaged atmospheric dispersion factor and ground deposition factor produced using two classification methods of atmospheric stability, which are based on a vertical temperature difference and the standard deviation of horizontal wind direction fluctuation. Daedeok and Wolsong nuclear sites were chosen for an assessment, and the meteorological data at 10 m were applied to the evaluation of atmospheric stability. The XOQDOQ software program was used to calculate atmospheric dispersion factors and ground deposition factors. The calculated distances were chosen at 400 m, 800 m, 1,200 m, 1,600 m, 2,400 m, and 3,200 m away from the radioactive material release points. All of the atmospheric dispersion factors generated using the atmospheric stability based on the vertical temperature difference were shown to be higher than those from the standard deviation of horizontal wind direction fluctuation. On the other hand, the ground deposition factors were shown to be same regardless of the classification method, as they were based on the graph obtained from empirical data presented in the Nuclear Regulatory Commission's Regulatory Guide 1.111, which is unrelated to the atmospheric stability for the ground level release. These results are based on the meteorological data collected over the course of one year at the specified sites; however, the classification method of atmospheric stability using the vertical temperature difference is expected to be more conservative.

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

    Directory of Open Access Journals (Sweden)

    R. Palomino-Merino

    2013-01-01

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

  1. A review of studies on atmospheric mercury in China.

    Science.gov (United States)

    Fu, Xuewu; Feng, Xinbin; Sommar, Jonas; Wang, Shaofeng

    2012-04-01

    Due to the fast developing economy, mercury (Hg) emissions to the atmosphere from Chinese mainland have increased rapidly in recent years. Consequently, this issue has received a considerable attention internationally. This paper reviews the current understanding of and knowledge on atmospheric Hg emissions, distribution and transport in China. The magnitude of Hg emissions to the atmosphere from Chinese anthropogenic sources has been estimated to be in the range of 500-700 tons per year, whereby comprising a significant proportion of the globe total anthropogenic emissions. Emissions of Hg from natural surfaces including bare soil, water, and vegetation covered soil tend in a comparison to be higher in China than in Europe and North America, indicating the importance of this source category. Atmospheric Hg exhibits a significant concentration variability among urban, semi-remote, and remote areas. Total Gaseous Mercury (TGM) concentrations in urban areas of China were often 1.5 - 5 folds higher compared to the corresponding settings in North America and Europe. In turn, particulate mercury (PHg) concentrations in urban areas of China were up to two orders of magnitude higher compared to North America and Europe. Atmospheric observations made at strictly remote sites in China also include the presence of occasional high concentrations of TGM, and the more short-lived fractions PHg and Reactive Gaseous Mercury (RGM). Accordingly, Hg deposition fluxes tended to be higher in China, with remote areas and urban areas being 1-2 times and 1-2 magnitude higher than those in North America and Europe, respectively. Crown Copyright © 2011. Published by Elsevier B.V. All rights reserved.

  2. Modelling atmospheric deposition flux of Cadmium and Lead in urban areas

    International Nuclear Information System (INIS)

    Cherin, Nicolas

    2017-01-01

    According to WHO, air pollution is responsible for more than 3.7 million premature deaths each year (OMS, 2014). Moreover, among these deaths, more than 70 within urban areas. Consequently, the health and environmental impacts of pollutants within these urban areas are of great concern in air quality studies. The deposition fluxes of air pollutants, which can be significant near sources of pollution, have rarely been modeled within urban areas. Historically, atmospheric deposition studies have focused mostly on remote areas to assess the potential impacts on ecosystems of acid deposition and nitrogen loading. Therefore, current atmospheric deposition models may not be suitable to simulate deposition fluxes in urban areas, which include complex surface geometries and diverse land use types. Atmospheric dry deposition is typically modeled using an average roughness length, which depends on land use. This classical roughness-length approach cannot account for the spatial variability of dry deposition in complex settings such as urban areas. Urban canopy models have been developed to parameterize momentum and heat transfer. We extend this approach here to mass transfer, and a new dry deposition model based on the urban canyon concept is presented. It uses a local mixing-length parameterization of turbulence within the canopy, and a description of the urban canopy via key parameters to provide spatially distributed dry deposition fluxes. This approach provides spatially distributed dry deposition fluxes depending on surfaces (streets, walls, roofs) and flow regimes (recirculation and ventilation) within the urban area. (author) [fr

  3. Trends in the chemistry of atmospheric deposition and surface waters in the Lake Maggiore catchment

    Directory of Open Access Journals (Sweden)

    M. Rogora

    2001-01-01

    Full Text Available The Lake Maggiore catchment is the area of Italy most affected by acid deposition. Trend analysis was performed on long-term (15-30 years series of chemical analyses of atmospheric deposition, four small rivers draining forested catchments and four high mountain lakes. An improvement in the quality of atmospheric deposition was detected, due to decreasing sulphate concentration and increasing pH. Similar trends were also found in high mountain lakes and in small rivers. Atmospheric deposition, however, is still providing a large and steady flux of nitrogen compounds (nitrate and ammonium which is causing increasing nitrogen saturation in forest ecosystems and increasing nitrate levels in rivers. Besides atmospheric deposition, an important factor controlling water acidification and recovery is the weathering of rocks and soils which may be influenced by climate warming. A further factor is the episodic deposition of Saharan calcareous dust which contributes significantly to base cation deposition. Keywords: trend, atmospheric deposition, nitrogen, stream water chemistry.

  4. Observed decrease in atmospheric mercury explained by global decline in anthropogenic emissions

    Science.gov (United States)

    Yanxu Zhang,; Daniel J. Jacob,; Hannah M. Horowitz,; Long Chen,; Helen M. Amos,; Krabbenhoft, David P.; Franz Slemr,; Vincent L. St. Louis,; Elsie M. Sunderland,

    2015-01-01

    Observations of elemental mercury (Hg0) at sites in North America and Europe show large decreases (∼1–2% y−1) from 1990 to present. Observations in background northern hemisphere air, including Mauna Loa Observatory (Hawaii) and CARIBIC (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container) aircraft flights, show weaker decreases (inventories indicating flat or increasing emissions over that period. However, the inventories have three major flaws: (i) they do not account for the decline in atmospheric release of Hg from commercial products; (ii) they are biased in their estimate of artisanal and small-scale gold mining emissions; and (iii) they do not properly account for the change in Hg0/HgII speciation of emissions from coal-fired utilities after implementation of emission controls targeted at SO2 and NOx. We construct an improved global emission inventory for the period 1990 to 2010 accounting for the above factors and find a 20% decrease in total Hg emissions and a 30% decrease in anthropogenic Hg0 emissions, with much larger decreases in North America and Europe offsetting the effect of increasing emissions in Asia. Implementation of our inventory in a global 3D atmospheric Hg simulation [GEOS-Chem (Goddard Earth Observing System-Chemistry)] coupled to land and ocean reservoirs reproduces the observed large-scale trends in atmospheric Hg0 concentrations and in HgII wet deposition. The large trends observed in North America and Europe reflect the phase-out of Hg from commercial products as well as the cobenefit from SO2 and NOx emission controls on coal-fired utilities.

  5. Spatial atmospheric atomic layer deposition of alxzn1-xo

    NARCIS (Netherlands)

    Illiberi, A.; Scherpenborg, R.; Wu, Y.; Roozeboom, F.; Poodt, P.

    2013-01-01

    The possibility of growing multicomponent oxides by spatial atmospheric atomic layer deposition has been investigated. To this end, Al xZn1-xO films have been deposited using diethyl zinc (DEZ), trimethyl aluminum (TMA), and water as Zn, Al, and O precursors, respectively. When the metal precursors

  6. Annual ambient atmospheric mercury speciation measurement from Longjing, a rural site in Taiwan.

    Science.gov (United States)

    Fang, Guor-Cheng; Lo, Chaur-Tsuen; Cho, Meng-Hsien; Zhuang, Yuan-Jie; Tsai, Kai-Hsiang; Huang, Chao-Yang; Xiao, You-Fu

    2017-08-01

    The main purpose of this study was to monitor ambient air particulates and mercury species [RGM, Hg(p), GEM and total mercury] concentrations and dry depositions over rural area at Longjing in central Taiwan during October 2014 to September 2015. In addition, passive air sampler and knife-edge surrogate surface samplers were used to collect the ambient air mercury species concentrations and dry depositions, respectively, in this study. Moreover, direct mercury analyzer was directly used to detect the mercury Hg(p) and RGM concentrations. The result indicated that: (1) The average highest RGM, Hg(p), GEM and total mercury concentrations, and dry depositions were observed in January, prevailing dust storm occurred in winter season was the possible major reason responsible for the above findings. (2) The highest average RGM, Hg(p), GEM and total mercury concentrations, dry depositions and velocities were occurred in winter. This is because that China is the largest atmospheric mercury (Hg) emitter in the world. Its Hg emissions and environmental impacts need to be evaluated. (3) The results indicated that the total mercury ratios of Kaohsiung to that of this study were 5.61. This is because that Kaohsiung has the largest industry density (~60 %) in Taiwan. (4) the USA showed average lower mercury species concentrations when compared to those of the other world countries. The average ratios of China/USA values were 89, 76 and 160 for total mercury, RGM and Hg(p), respectively, during the years of 2000-2012.

  7. Source apportionment of atmospheric mercury pollution in China using the GEOS-Chem model.

    Science.gov (United States)

    Wang, Long; Wang, Shuxiao; Zhang, Lei; Wang, Yuxuan; Zhang, Yanxu; Nielsen, Chris; McElroy, Michael B; Hao, Jiming

    2014-07-01

    China is the largest atmospheric mercury (Hg) emitter in the world. Its Hg emissions and environmental impacts need to be evaluated. In this study, China's Hg emission inventory is updated to 2007 and applied in the GEOS-Chem model to simulate the Hg concentrations and depositions in China. Results indicate that simulations agree well with observed background Hg concentrations. The anthropogenic sources contributed 35-50% of THg concentration and 50-70% of total deposition in polluted regions. Sensitivity analysis was performed to assess the impacts of mercury emissions from power plants, non-ferrous metal smelters and cement plants. It is found that power plants are the most important emission sources in the North China, the Yangtze River Delta (YRD) and the Pearl River Delta (PRD) while the contribution of non-ferrous metal smelters is most significant in the Southwest China. The impacts of cement plants are significant in the YRD, PRD and Central China. Copyright © 2014 Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

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

    2016-09-01

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

  9. Atmospheric Nitrogen Deposition in the Western United States: Sources, Sinks and Changes over Time

    Science.gov (United States)

    Anderson, Sarah Marie

    Anthropogenic activities have greatly modified the way nitrogen moves through the atmosphere and terrestrial and aquatic environments. Excess reactive nitrogen generated through fossil fuel combustion, industrial fixation, and intensification of agriculture is not confined to anthropogenic systems but leaks into natural ecosystems with consequences including acidification, eutrophication, and biodiversity loss. A better understanding of where excess nitrogen originates and how that changes over time is crucial to identifying when, where, and to what degree environmental impacts occur. A major route into ecosystems for excess nitrogen is through atmospheric deposition. Excess nitrogen is emitted to the atmosphere where it can be transported great distances before being deposited back to the Earth's surface. Analyzing the composition of atmospheric nitrogen deposition and biological indicators that reflect deposition can provide insight into the emission sources as well as processes and atmospheric chemistry that occur during transport and what drives variation in these sources and processes. Chapter 1 provides a review and proof of concept of lichens to act as biological indicators and how their elemental and stable isotope composition can elucidate variation in amounts and emission sources of nitrogen over space and time. Information on amounts and emission sources of nitrogen deposition helps inform natural resources and land management decisions by helping to identify potentially impacted areas and causes of those impacts. Chapter 2 demonstrates that herbaria lichen specimens and field lichen samples reflect historical changes in atmospheric nitrogen deposition from urban and agricultural sources across the western United States. Nitrogen deposition increases throughout most of the 20 th century because of multiple types of emission sources until the implementation of the Clean Air Act Amendments of 1990 eventually decrease nitrogen deposition around the turn of

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

    Science.gov (United States)

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

    2015-01-01

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

  11. Updated atmospheric speciated mercury emissions from iron and steel production in China during 2000-2015

    Science.gov (United States)

    Wu, Qingru; Gao, Wei; Wang, Shuxiao; Hao, Jiming

    2017-09-01

    Iron and steel production (ISP) is one of the significant atmospheric Hg emission sources in China. Atmospheric mercury (Hg) emissions from ISP during 2000-2015 were estimated by using a technology-based emission factor method. To support the application of this method, databases of Hg concentrations in raw materials, technology development trends, and Hg removal efficiencies of air pollution control devices (APCDs) were constructed through national sampling and literature review. Hg input to ISP increased from 21.6 t in 2000 to 94.5 t in 2015. In the various types of raw materials, coking coal and iron concentrates contributed 35-46 and 25-32 % of the total Hg input. Atmospheric Hg emissions from ISP increased from 11.5 t in 2000 to 32.7 t in 2015 with a peak of 35.6 t in 2013. Pollution control promoted the increase in average Hg removal efficiency, from 47 % in 2000 to 65 % in 2015. During the study period, sinter/pellet plants and blast furnaces were the largest two emission processes. However, emissions from roasting plants and coke ovens cannot be ignored, which accounted for 22-34 % of ISP's emissions. Overall, Hg speciation shifted from 50/44/6 (gaseous elemental Hg (Hg0)/gaseous oxidized Hg (HgII)/particulate-bound Hg (Hgp)) in 2000 to 40/59/1 in 2015, which indicated a higher proportion of Hg deposition around the emission points. Future emissions of ISP were expected to decrease based on the comprehensive consideration crude-steel production, steel scrap utilization, energy saving, and pollution control measures.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-05-15

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

  13. Human health risk assessment of lead pollution in atmospheric deposition in Baoshan District, Shanghai.

    Science.gov (United States)

    Chen, Yuanyuan; Wang, Jun; Shi, Guitao; Sun, Xiaojing; Chen, Zhenlou; Xu, Shiyuan

    2011-12-01

    The lead (Pb) content in atmospheric deposition was determined at 42 sampling sites in Baoshan District of Shanghai, China. Based on exposure and dose-response assessments, the health risk caused by Pb exposure in atmospheric deposition was investigated. The results indicated that Pb was significantly accumulated in atmospheric deposition. The spatial distribution of Pb was mapped by geostatistical analysis, and the results showed that pollution hotspots were present at traffic and industrial zones. Ingestion was the main route of Pb exposure in both adults and children. For children the risk value was above 1, whereas it was below 1 for the adult group. Therefore, children belong to the high-risk group for Pb exposure from atmospheric deposition in the observed area of Shanghai, China.

  14. Contribution of Asian dust to atmospheric deposition of radioactive cesium (137Cs)

    International Nuclear Information System (INIS)

    Fukuyama, Taijiro; Fujiwara, Hideshi

    2008-01-01

    Both Asian dust (kosa) transported from the East Asian continent and locally suspended dust near monitoring sites contribute to the observed atmospheric deposition of 137 Cs in Japan. To estimate the relative contribution of these dust phenomena to the total 137 Cs deposition, we monitored weekly deposition of mineral particles and 137 Cs in spring. Deposition of 137 Cs from a single Asian dust event was 62.3 mBq m -2 and accounted for 67% of the total 137 Cs deposition during the entire monitoring period. Furthermore, we found high 137 Cs specific activity in the Asian dust deposition sample. Although local dust events contributed to 137 Cs deposition, their contribution was considerably smaller than that of Asian dust. We conclude that the primary source of atmospheric 137 Cs in Japan is dust transported from the East Asian continent

  15. Measurement of forest condition and response along the Pennsylvania atmospheric deposition gradent

    Science.gov (United States)

    D.D. David; J.M. Skelly; J.A. Lynch; L.H. McCormick; B.L. Nash; M. Simini; E.A. Cameron; J.R. McClenahen; R.P. Long

    1991-01-01

    Research in the oak-hickory forest of northcentral Pennsylvania is being conducted to detect anomalies in forest condition that may be due to atmospheric deposition, with the intent that such anomalies will be further studied to determine the role, if any, of atmospheric deposition. This paper presents the status of research along a 160-km gradient of sulfate/nitrate...

  16. New insights into the atmospheric mercury cycling in central Antarctica and implications on a continental scale

    Directory of Open Access Journals (Sweden)

    H. Angot

    2016-07-01

    Full Text Available Under the framework of the GMOS project (Global Mercury Observation System atmospheric mercury monitoring has been implemented at Concordia Station on the high-altitude Antarctic plateau (75°06′ S, 123°20′ E, 3220 m above sea level. We report here the first year-round measurements of gaseous elemental mercury (Hg(0 in the atmosphere and in snowpack interstitial air on the East Antarctic ice sheet. This unique data set shows evidence of an intense oxidation of atmospheric Hg(0 in summer (24-hour daylight due to the high oxidative capacity of the Antarctic plateau atmosphere in this period of the year. Summertime Hg(0 concentrations exhibited a pronounced daily cycle in ambient air with maximal concentrations around midday. Photochemical reactions and chemical exchange at the air–snow interface were prominent, highlighting the role of the snowpack on the atmospheric mercury cycle. Our observations reveal a 20 to 30 % decrease of atmospheric Hg(0 concentrations from May to mid-August (winter, 24 h darkness. This phenomenon has not been reported elsewhere and possibly results from the dry deposition of Hg(0 onto the snowpack. We also reveal the occurrence of multi-day to weeklong atmospheric Hg(0 depletion events in summer, not associated with depletions of ozone, and likely due to a stagnation of air masses above the plateau triggering an accumulation of oxidants within the shallow boundary layer. Our observations suggest that the inland atmospheric reservoir is depleted in Hg(0 in summer. Due to katabatic winds flowing out from the Antarctic plateau down the steep vertical drops along the coast and according to observations at coastal Antarctic stations, the striking reactivity observed on the plateau most likely influences the cycle of atmospheric mercury on a continental scale.

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

    Science.gov (United States)

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

    2016-01-01

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

  18. Atmospheric Deposition of Heavy Metals in Soil Affected by Different Soil Uses of Southern Spain

    Science.gov (United States)

    Acosta, J. A.; Faz, A.; Martínez-Martínez, S.; Bech, J.

    2009-04-01

    Heavy metals are a natural constituent of rocks, sediments and soils. However, the heavy metal content of top soils is also dependent on other sources than weathering of the indigenous minerals; input from atmospheric deposition seems to be an important pathway. Atmospheric deposition is defined as the process by which atmospheric pollutants are transferred to terrestrial and aquatic surfaces and is commonly classified as either dry or wet. The interest in atmospheric deposition has increased over the past decade due to concerns about the effects of deposited materials on the environment. Dry deposition provides a significant mechanism for the removal of particles from the atmosphere and is an important pathway for the loading of heavy metals into the soil ecosystem. Within the last decade, an intensive effort has been made to determine the atmospheric heavy metal deposition in both urban and rural areas. The main objective of this study was to identification of atmospheric heavy metals deposition in soil affected by different soil uses. Study area is located in Murcia Province (southeast of Spain), in the surroundings of Murcia City. The climate is typically semiarid Mediterranean with an annual average temperature of 18°C and precipitation of 350 mm. In order to determine heavy metals atmospheric deposition a sampling at different depths (0-1 cm, 1-5 cm, 5-15 cm and 15-30 cm) was carried out in 7 sites including agricultural soils, two industrial areas and natural sites. The samples were taken to the laboratory where, dried, passed through a 2 mm sieve, and grinded. For the determination of the moisture the samples were weighed and oven dried at 105 °C for 24 h. The total amounts of metals (Pb, Cu, Pb, Zn, Cd, Mn, Ni and Cr) were determined by digesting the samples with nitric/perchoric acids and measuring with ICP-MS. Results showed that zinc contamination in some samples of industrial areas was detected, even this contamination reaches 30 cm depth; thus it is

  19. Litterfall mercury dry deposition in the eastern USA

    International Nuclear Information System (INIS)

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

    2012-01-01

    Mercury (Hg) in autumn litterfall from predominately deciduous forests was measured in 3 years of samples from 23 Mercury Deposition Network sites in 15 states across the eastern USA. Annual litterfall Hg dry deposition was significantly higher (median 12.3 micrograms per square meter (μg/m 2 ), range 3.5–23.4 μg/m 2 ) than annual Hg wet deposition (median 9.6 μg/m 2 , range 4.4–19.7 μg/m 2 ). The mean ratio of dry to wet Hg deposition was 1.3–1. The sum of dry and wet Hg deposition averaged 21 μg/m 2 per year and 55% was litterfall dry deposition. Methylmercury was a median 0.8% of Hg in litterfall and ranged from 0.6 to 1.5%. Annual litterfall Hg and wet Hg deposition rates differed significantly and were weakly correlated. Litterfall Hg dry deposition differed among forest-cover types. This study demonstrated how annual litterfall Hg dry deposition rates approximate the lower bound of annual Hg dry fluxes. - Highlights: ► Annual litterfall mercury dry deposition was significantly higher than wet deposition. ► The mean ratio of dry to wet mercury deposition was 1.3–1. ► The sum of dry and wet mercury deposition averaged 55% litterfall dry deposition. ► Litterfall mercury deposition was highest in the oak-hickory forest-cover type. ► Methylmercury was a median 0.8% of mercury in litterfall and ranged to 1.5%. - A multi-year study of Mercury Deposition Network sites found that annual mercury dry deposition from litterfall in predominately deciduous forests exceeded annual mercury wet deposition in the eastern USA.

  20. Atmospheric wet deposition of mercury in North America

    Energy Technology Data Exchange (ETDEWEB)

    Sweet, C.W.; Prestbo, E.; Brunette, B.

    1999-07-01

    Currently, 39 states in the US and 5 Canadian provinces have issued advisories about the dangers of eating mercury-contaminated fish taken from waters within their boundaries. The problem is most severe in the Great Lakes region, the Northeast US states, the Canadian maritime provinces, and in south Florida where many lakes and streams contain fish with concentrations of 1 ppm or higher. For many rural and remote locations, atmospheric deposition is the primary source of mercury. In 1995, the National Atmospheric Deposition Program (NADP) initiated a program to monitor total mercury and methylmercury (MMHg) in wet deposition (rain and snow) in North America. In this program, the Mercury Deposition Network (MDN), individual monitoring sites are funded and operated by a variety of local, state, and federal agencies. However, sampling and analysis are coordinated through a central laboratory so that all of the samples are collected and analyzed using the same protocols. Weekly wet-only precipitation samples are collected using an all-glass sampling train and special handling techniques. Analysis is by cold vapor atomic fluorescence spectrometry using USEPA Method 1631 for total mercury. Nearly 40 MDN sites are in operation in 1999. Most of the sites are in the eastern US and Canada. During 1996 and 1997, the volume-weighted mean concentration of total mercury in precipitation collected at 22 sites ranged from 6.0 to 18.9 ng/L. Annual deposition varied between 2.1 and 25.3 {micro} g/m{sup 2}. The average weekly wet deposition of total mercury is more than three times higher in the summer (June-August) than in the winter (December-February). This increase is due to both higher amounts of precipitation and higher concentrations of mercury in precipitation during the summer. The highest values for mercury concentration in precipitation and wet deposition of mercury were measured in the southeastern US.

  1. Oceanic Emissions and Atmospheric Depositions of Volatile Organic Compounds

    Science.gov (United States)

    Yang, M.; Blomquist, B.; Beale, R.; Nightingale, P. D.; Liss, P. S.

    2015-12-01

    Atmospheric volatile organic compounds (VOCs) affect the tropospheric oxidative capacity due to their ubiquitous abundance and relatively high reactivity towards the hydroxyal radical. Over the ocean and away from terrestrial emission sources, oxygenated volatile organic compounds (OVOCs) make up a large fraction of VOCs as airmasses age and become more oxidized. In addition to being produced or destroyed in the marine atmosphere, OVOCs can also be emitted from or deposited to the surface ocean. Here we first present direct air-sea flux measurements of three of the most abundant OVOCs - methanol, acetone, and acetaldehyde, by the eddy covariance technique from two cruises in the Atlantic: the Atlantic Meridional Transect in 2012 and the High Wind Gas Exchange Study in 2013. The OVOC mixing ratios were quantified by a high resolution proton-reaction-transfer mass spectrometer with isotopically labeled standards and their air-sea (net) fluxes were derived from the eddy covariance technique. Net methanol flux was consistently from the atmosphere to the surface ocean, while acetone varied from supersaturation (emission) in the subtropics to undersaturation (deposition) in the higher latitudes of the North Atlantic. The net air-sea flux of acetaldehyde is near zero through out the Atlantic despite the apparent supersaturation of this compound in the surface ocean. Knowing the dissolved concentrations and in situ production rates of these compounds in seawater, we then estimate their bulk atmospheric depositions and oceanic emissions. Lastly, we summarize the state of knowledge on the air-sea transport of a number of organic gasses, and postulate the magnitude and environmental impact of total organic carbon transfer between the ocean and the atmosphere.

  2. Standard test method for determining atmospheric chloride deposition rate by wet candle method

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2002-01-01

    1.1 This test method covers a wet candle device and its use in measuring atmospheric chloride deposition (amount of chloride salts deposited from the atmosphere on a given area per unit time). 1.2 Data on atmospheric chloride deposition can be useful in classifying the corrosivity of a specific area, such as an atmospheric test site. Caution must be exercised, however, to take into consideration the season because airborne chlorides vary widely between seasons. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

  3. Recent Advances in Atmospheric Vapor-Phase Deposition of Transparent and Conductive Zinc Oxide

    NARCIS (Netherlands)

    Illiberi, A.; Poodt, P.; Roozeboom, F.

    2014-01-01

    The industrial need for high-throughput and low-cost ZnO deposition processes has triggered the development of atmospheric vapor-phase deposition techniques which can be easily applied to continuous, in-line manufacturing. While atmospheric CVD is a mature technology, new processes for the growth of

  4. Atmospheric deposition of 137Cs between 1994 and 2002 at Cienfuegos, Cuba

    International Nuclear Information System (INIS)

    Alonso-Hernandez, C.M.; Cartas-Aguila, H.; Diaz-Asencio, M.; Munoz-Caravaca, A.; Martin-Perez, J.; Sibello-Hernandez, R.

    2006-01-01

    Levels of 137 Cs in total atmospheric deposition have been measured in the Cienfuegos region (Cuba) between 1994 and 2002. Samples were collected every three months, evaporated to dryness to obtain residual samples, and measured by gamma spectrometry. The 137 Cs mean concentration in total deposition was 0.24 Bq m -2 and data ranged between -2 . Precipitation rates and raintime have proved to be the most important factors controlling the concentration and depositional flux of 137 Cs in the atmosphere over Cienfuegos, showing a high correlation coefficient (R = 0.93)

  5. HTO deposition by vapor exchange between atmosphere and soil

    International Nuclear Information System (INIS)

    Bunnenberg, C.

    1989-01-01

    HTO deposition to soils occurs by vapor exchange between atmosphere and soil-air, when the concentration gradient is directed downwards, and it is principally independent from simultaneous transport of H 2 O. In relatively dry top soil, which is frequently the case, as it tries to attain equilibrium with the air humidity, HTO diffuses into deeper soil driven by the same mechanisms that caused the deposition process. The resulting HTO profile is depending on the atmospheric supply and the soil physical conditions, and it is the source for further tritium pathways, namely root uptake by plants and reemission from soil back into the ground-level air. Simulation experiments with soil columns exposed to HTO labeled atmospheres have proved the theoretical expectation that under certain boundary conditions the HTO profile can be described by an error function. The key parameter is the effective diffusion coefficient, which in turn is a function of the sorption characteristics of the particular soil. (orig.) [de

  6. Atmospheric bulk deposition of polycyclic aromatic hydrocarbons in Shanghai: Temporal and spatial variation, and global comparison

    International Nuclear Information System (INIS)

    Feng, Daolun; Liu, Ying; Gao, Yi; Zhou, Jinxing; Zheng, Lirong; Qiao, Gang; Ma, Liming; Lin, Zhifen; Grathwohl, Peter

    2017-01-01

    Atmospheric deposition leads to accumulation of atmospheric polycyclic aromatic hydrocarbons (PAHs) on urban surfaces and topsoils. To capture the inherent variability of atmospheric deposition of PAHs in Shanghai's urban agglomeration, 85 atmospheric bulk deposition samples and 7 surface soil samples were collected from seven sampling locations during 2012–2014. Total fluxes of 17 PAHs were 587-32,300 ng m −2 day −1 , with a geometric mean of 2600 ng m −2 day −1 . The deposition fluxes were categorized as moderate to high on a global scale. Phenanthrene, fluoranthene and pyrene were major contributors. The spatial distribution of deposition fluxes revealed the influence of urbanization/industrialization and the relevance of local emissions. Meteorological conditions and more heating demand in cold season lead to a significant increase of deposition rates. Atmospheric deposition is the principal pathway of PAHs input to topsoils and the annual deposition load in Shanghai amounts to ∼4.5 tons (0.7 kg km −2 ) with a range of 2.5–10 tons (0.4–1.6 kg km −2 ). - Highlights: • PAH deposition flux in Shanghai is categorized as moderate to high on global scale. • Their spatial distribution reveals the influence of urbanization/industrialization. • Atmospheric deposition is the principal pathway of PAHs input to local topsoils. • Other pathways have to be considered for PAH input in urban soil. - Atmospheric deposition of PAHs revealed the influence of urbanization and industrialization and the relevance of local emissions on Shanghai topsoils.

  7. Lichen-based critical loads for atmospheric nitrogen deposition in Western Oregon and Washington forests, USA

    Science.gov (United States)

    Linda H. Geiser; Sarah E. Jovan; Doug A. Glavich; Matthew K. Porter

    2010-01-01

    Critical loads (CLs) define maximum atmospheric deposition levels apparently preventative of ecosystem harm. We present first nitrogen CLs for northwestern North America's maritime forests. Using multiple linear regression, we related epiphytic-macrolichen community composition to: 1) wet deposition from the National Atmospheric Deposition Program, 2) wet, dry,...

  8. Atmospheric bulk deposition of polycyclic aromatic hydrocarbons in Shanghai: Temporal and spatial variation, and global comparison.

    Science.gov (United States)

    Feng, Daolun; Liu, Ying; Gao, Yi; Zhou, Jinxing; Zheng, Lirong; Qiao, Gang; Ma, Liming; Lin, Zhifen; Grathwohl, Peter

    2017-11-01

    Atmospheric deposition leads to accumulation of atmospheric polycyclic aromatic hydrocarbons (PAHs) on urban surfaces and topsoils. To capture the inherent variability of atmospheric deposition of PAHs in Shanghai's urban agglomeration, 85 atmospheric bulk deposition samples and 7 surface soil samples were collected from seven sampling locations during 2012-2014. Total fluxes of 17 PAHs were 587-32,300 ng m -2 day -1 , with a geometric mean of 2600 ng m -2 day -1 . The deposition fluxes were categorized as moderate to high on a global scale. Phenanthrene, fluoranthene and pyrene were major contributors. The spatial distribution of deposition fluxes revealed the influence of urbanization/industrialization and the relevance of local emissions. Meteorological conditions and more heating demand in cold season lead to a significant increase of deposition rates. Atmospheric deposition is the principal pathway of PAHs input to topsoils and the annual deposition load in Shanghai amounts to ∼4.5 tons (0.7 kg km -2 ) with a range of 2.5-10 tons (0.4-1.6 kg km -2 ). Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Beryllium abundances in Hg-Mn stars

    International Nuclear Information System (INIS)

    Boesgaard, A.M.; Heacox, W.D.; Wolff, S.C.; Borsenberger, J.; Praderie, F.

    1982-01-01

    The Hg-Mn stars show anomalous line strengths of many chemical elements including Be. We have observed the Be ii resonance doublet at lambdalambda 3130, 3131 at 6.7 A mm -1 in 43 Hg-Mn stars and 10 normal stars in the same temperature range with the coude spectrograph of the 2.24 m University of Hawaii telescope at Mauna Kea. Measured equivalent widths of the two lines and/or the blend of the doublet have been compared with predictions from (1) LTE model atmospheres and (2) non-LTE line formation on non-LTE model atmospheres. (For strong Be ii lines, the LTE calculations result in more Be by factors of 2 to 4 than do the non-LTE calculations.) Overabundances of factors of 20--2 x 10 4 relative to solar have been found for 75% of the Hg-Mn stars. The 25% with little or no Be are typically among the cooler Hg-Mn stars, but for the stars with Be excesses, there is only marginal evidence for a correlationi of the size of the overabundance and temperature. It is suggested that diffusion driven by radiation pressure is responsible for the observed Be abundance anomalies

  10. Updated atmospheric speciated mercury emissions from iron and steel production in China during 2000–2015

    Directory of Open Access Journals (Sweden)

    Q. Wu

    2017-09-01

    Full Text Available Iron and steel production (ISP is one of the significant atmospheric Hg emission sources in China. Atmospheric mercury (Hg emissions from ISP during 2000–2015 were estimated by using a technology-based emission factor method. To support the application of this method, databases of Hg concentrations in raw materials, technology development trends, and Hg removal efficiencies of air pollution control devices (APCDs were constructed through national sampling and literature review. Hg input to ISP increased from 21.6 t in 2000 to 94.5 t in 2015. In the various types of raw materials, coking coal and iron concentrates contributed 35–46 and 25–32 % of the total Hg input. Atmospheric Hg emissions from ISP increased from 11.5 t in 2000 to 32.7 t in 2015 with a peak of 35.6 t in 2013. Pollution control promoted the increase in average Hg removal efficiency, from 47 % in 2000 to 65 % in 2015. During the study period, sinter/pellet plants and blast furnaces were the largest two emission processes. However, emissions from roasting plants and coke ovens cannot be ignored, which accounted for 22–34 % of ISP's emissions. Overall, Hg speciation shifted from 50/44/6 (gaseous elemental Hg (Hg0/gaseous oxidized Hg (HgII/particulate-bound Hg (Hgp in 2000 to 40/59/1 in 2015, which indicated a higher proportion of Hg deposition around the emission points. Future emissions of ISP were expected to decrease based on the comprehensive consideration crude-steel production, steel scrap utilization, energy saving, and pollution control measures.

  11. Dust cloud evolution in sub-stellar atmospheres via plasma deposition and plasma sputtering

    Science.gov (United States)

    Stark, C. R.; Diver, D. A.

    2018-04-01

    Context. In contemporary sub-stellar model atmospheres, dust growth occurs through neutral gas-phase surface chemistry. Recently, there has been a growing body of theoretical and observational evidence suggesting that ionisation processes can also occur. As a result, atmospheres are populated by regions composed of plasma, gas and dust, and the consequent influence of plasma processes on dust evolution is enhanced. Aim. This paper aims to introduce a new model of dust growth and destruction in sub-stellar atmospheres via plasma deposition and plasma sputtering. Methods: Using example sub-stellar atmospheres from DRIFT-PHOENIX, we have compared plasma deposition and sputtering timescales to those from neutral gas-phase surface chemistry to ascertain their regimes of influence. We calculated the plasma sputtering yield and discuss the circumstances where plasma sputtering dominates over deposition. Results: Within the highest dust density cloud regions, plasma deposition and sputtering dominates over neutral gas-phase surface chemistry if the degree of ionisation is ≳10-4. Loosely bound grains with surface binding energies of the order of 0.1-1 eV are susceptible to destruction through plasma sputtering for feasible degrees of ionisation and electron temperatures; whereas, strong crystalline grains with binding energies of the order 10 eV are resistant to sputtering. Conclusions: The mathematical framework outlined sets the foundation for the inclusion of plasma deposition and plasma sputtering in global dust cloud formation models of sub-stellar atmospheres.

  12. Acid atmospheric deposition in a forested mountain catchment

    Czech Academy of Sciences Publication Activity Database

    Křeček, J.; Palán, L.; Stuchlík, Evžen

    2017-01-01

    Roč. 10, č. 4 (2017), s. 680-686 ISSN 1971-7458 Institutional support: RVO:60077344 Keywords : mountain water shed * spruce forests * acid atmospheric deposition * water resources recharge Subject RIV: DA - Hydrology ; Limnology OBOR OECD: Marine biology, freshwater biology, limnology Impact factor: 1.623, year: 2016

  13. Estimating chemical composition of atmospheric deposition fluxes from mineral insoluble particles deposition collected in the western Mediterranean region

    Directory of Open Access Journals (Sweden)

    Y. Fu

    2017-11-01

    Full Text Available In order to measure the mass flux of atmospheric insoluble deposition and to constrain regional models of dust simulation, a network of automatic deposition collectors (CARAGA has been installed throughout the western Mediterranean Basin. Weekly samples of the insoluble fraction of total atmospheric deposition were collected concurrently on filters at five sites including four on western Mediterranean islands (Frioul and Corsica, France; Mallorca, Spain; and Lampedusa, Italy and one in the southern French Alps (Le Casset, and a weighing and ignition protocol was applied in order to quantify their mineral fraction. Atmospheric deposition is both a strong source of nutrients and metals for marine ecosystems in this area. However, there are few data on trace-metal deposition in the literature, since their deposition measurement is difficult to perform. In order to obtain more information from CARAGA atmospheric deposition samples, this study aimed to test their relevance in estimating elemental fluxes in addition to total mass fluxes. The elemental chemical analysis of ashed CARAGA filter samples was based on an acid digestion and an elemental analysis by inductively coupled plasma atomic emission spectroscopy (ICP-AES and mass spectrometry (MS in a clean room. The sampling and analytical protocols were tested to determine the elemental composition for mineral dust tracers (Al, Ca, K, Mg and Ti, nutrients (P and Fe and trace metals (Cd, Co, Cr, Cu, Mn, Ni, V and Zn from simulated wet deposition of dust analogues and traffic soot. The relative mass loss by dissolution in wet deposition was lower than 1 % for Al and Fe, and reached 13 % for P due to its larger solubility in water. For trace metals, this loss represented less than 3 % of the total mass concentration, except for Zn, Cu and Mn for which it could reach 10 %, especially in traffic soot. The chemical contamination during analysis was negligible for all the elements except for Cd

  14. Source apportionment of atmospheric bulk deposition in the Belgrade urban area using Positive Matrix factorization

    Science.gov (United States)

    Tasić, M.; Mijić, Z.; Rajšić, S.; Stojić, A.; Radenković, M.; Joksić, J.

    2009-04-01

    The primary objective of the present study was to assess anthropogenic impacts of heavy metals to the environment by determination of total atmospheric deposition of heavy metals. Atmospheric depositions (wet + dry) were collected monthly, from June 2002 to December 2006, at three urban locations in Belgrade, using bulk deposition samplers. Concentrations of Fe, Al, Pb, Zn, Cu, Ni, Mn, Cr, V, As and Cd were analyzed using atomic absorption spectrometry. Based upon these results, the study attempted to examine elemental associations in atmospheric deposition and to elucidate the potential sources of heavy metal contaminants in the region by the use of multivariate receptor model Positive Matrix Factorization (PMF).

  15. Source apportionment of atmospheric bulk deposition in the Belgrade urban area using Positive Matrix factorization

    International Nuclear Information System (INIS)

    Tasic, M; Mijic, Z; Rajsic, S; Stojic, A; Radenkovic, M; Joksic, J

    2009-01-01

    The primary objective of the present study was to assess anthropogenic impacts of heavy metals to the environment by determination of total atmospheric deposition of heavy metals. Atmospheric depositions (wet + dry) were collected monthly, from June 2002 to December 2006, at three urban locations in Belgrade, using bulk deposition samplers. Concentrations of Fe, Al, Pb, Zn, Cu, Ni, Mn, Cr, V, As and Cd were analyzed using atomic absorption spectrometry. Based upon these results, the study attempted to examine elemental associations in atmospheric deposition and to elucidate the potential sources of heavy metal contaminants in the region by the use of multivariate receptor model Positive Matrix Factorization (PMF).

  16. Biomonitoring along the french coastline: could mercury isotopic composition indicate a temporal change in hg reaching the coastal zone?

    OpenAIRE

    Briant, Nicolas; Chouvelon, Tiphaine; Brach-papa, Christophe; Chiffoleau, Jean-francois; Savoye, Nicolas; Sonke, Jeroen; Knoery, Joel

    2017-01-01

    Mercury (Hg) is a natural element toxic to all living organisms. Its ocean biogeochemical cycle is dominated by atmospheric deposition, which human activities contribute to disrupt signi cantly, and to a lesser extent by riverine discharge. This element is bioamplifed and bioaccumulated in marine food webs. since mercury concentrations in some coastal animal species of high trophic level approach sanitary thresholds, understanding biogeochemical processes and mechanisms leading to these eleva...

  17. Wet and Dry Atmospheric Depositions of Inorganic Nitrogen during Plant Growing Season in the Coastal Zone of Yellow River Delta

    Directory of Open Access Journals (Sweden)

    Junbao Yu

    2014-01-01

    Full Text Available The ecological problems caused by dry and wet deposition of atmospheric nitrogen have been widespread concern in the world. In this study, wet and dry atmospheric depositions were monitored in plant growing season in the coastal zone of the Yellow River Delta (YRD using automatic sampling equipment. The results showed that SO42- and Na+ were the predominant anion and cation, respectively, in both wet and dry atmospheric depositions. The total atmospheric nitrogen deposition was ~2264.24 mg m−2, in which dry atmospheric nitrogen deposition was about 32.02%. The highest values of dry and wet atmospheric nitrogen deposition appeared in May and August, respectively. In the studied area, NO3-–N was the main nitrogen form in dry deposition, while the predominant nitrogen in wet atmospheric deposition was NH4+–N with ~56.51% of total wet atmospheric nitrogen deposition. The average monthly attribution rate of atmospheric deposition of NO3-–N and NH4+–N was ~31.38% and ~20.50% for the contents of NO3-–N and NH4+–N in 0–10 cm soil layer, respectively, suggested that the atmospheric nitrogen was one of main sources for soil nitrogen in coastal zone of the YRD.

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

    Science.gov (United States)

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

    2014-01-01

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

  19. Atmospheric deposition and environmental quality in Italy

    International Nuclear Information System (INIS)

    Mosello, R.

    1993-01-01

    For Italy's Po River hydrological basin, artificial reservoirs have a great importance; water reserve is about 1600 million cubic meters for the hydroelectric reservoirs and about 76 million cubic meters for irrigation. Relevant to studies on water quality and acidification in the Po River Basin, this paper reviews some aspects of research on atmospheric deposition, i.e., geographical variability, long term trends, and effects on surface waters

  20. The deposition of radioiodine onto rice plant from atmosphere

    International Nuclear Information System (INIS)

    Uchida, Shigeo; Muramatsu, Yasuyuki; Yoshida, Satoshi; Sumiya, Misako; Ohmomo, Yoichiro.

    1994-01-01

    Radiation dose estimations are usually made with the aid of assessment models in which model parameters such as the transfer factors of radionuclides from one environmental compartment to another are involved. In simple models the parameters are often described as the concentration ratio of a radionuclide between two compartments, when the system is under equilibrium condition. In this paper, the authors introduce the values of the parameters of radioiodine obtained by tracer experiments. Laboratory experiments on the transfer parameters of radionuclides from the atmosphere to rice plant were carried out in the atmosphere-to-crops system (deposition pathway). It is known that the typical chemical species of gaseous iodine in the atmosphere are elemental iodine (I 2 ) and methyliodide (CH 3 I). The deposition characteristics of both chemical species of gaseous iodine to rice grains were obtained. Mass normalized deposition velocity (V D ) and grain number normalized deposition velocity (V S ) of gaseous elemental iodine (I 2 ) and also methyliodide (CH 3 I) on unhulled rice were measured. Both V D and V S of methyliodide were about one percent of those of elemental iodine. Distribution pattern of methyliodide between unhulled rice and brown rice was significantly lower than that of elemental one. For wet deposition, we investigated the retention of radioiodines (iodide [I - ] and iodate [IO 3 - ] on rice grains and their translocation from the surface of the grains to brown rice. Though the ears were dipped into the solution containing 125 I - or 125 IO 3 - more than 15 min., both iodine species in the solutions were hardly taken up to the rice grains. The transfer rates of iodide and iodate, which are defined as 'the amount of the iodine in brown rice' divided by 'the amount of iodide in unhulled rice' were about 0.015 and 0.04, respectively. The rates were not changed with time after the radioiodine application. (author)

  1. Atmospheric heavy metal deposition in the Copenhagen area

    DEFF Research Database (Denmark)

    Andersen, Allan; Hovmand, Mads Frederik; Johnsen, Ib

    1978-01-01

    Atmospheric dry and wet deposition (bulk precipitation) of the heavy metals Cu, Pb, Zn, Ni, V and Fe over the Copenhagen area was measured by sampling in plastic funnels from 17 stations during a twelve-month period. Epigeic bryophytes from 100 stations in the area were analysed for the heavy...

  2. Potential geographic distribution of atmospheric nitrogen deposition from intensive livestock production in North Carolina, USA

    International Nuclear Information System (INIS)

    Costanza, Jennifer K.; Marcinko, Sarah E.; Goewert, Ann E.; Mitchell, Charles E.

    2008-01-01

    To examine the consequences of increased spatial aggregation of livestock production facilities, we estimated the annual production of nitrogen in livestock waste in North Carolina, USA, and analyzed the potential distribution of atmospheric nitrogen deposition from confined animal feeding operations ('CAFO') lagoons. North Carolina is a national center for industrial livestock production. Livestock is increasingly being raised in CAFOs, where waste is frequently held, essentially untreated, in open-air lagoons. Reduced nitrogen in lagoons is volatilized as ammonia (NH 3 ), transported atmospherically, and deposited to other ecosystems. The Albemarle-Pamlico Sound, NC, is representative of nitrogen-sensitive coastal waters, and is a major component of the second largest estuarine complex in the U.S. We used GIS to model the area of water in the Sound within deposition range of CAFOs. We also evaluated the number of lagoons within deposition range of each 1 km 2 grid cell of the state. We considered multiple scenarios of atmospheric transport by varying distance and directionality. Modeled nitrogen deposition rates were particularly elevated for the Coastal Plain. This pattern matches empirical data, suggesting that observed regional patterns of reduced nitrogen deposition can be largely explained by two factors: limited atmospheric transport distance, and spatial aggregation of CAFOs. Under our medium-distance scenario, a small portion (roughly 22%) of livestock production facilities contributes disproportionately to atmospheric deposition of nitrogen to the Albemarle-Pamlico Sound. Furthermore, we estimated that between 14-37% of the state receives 50% of the state's atmospheric nitrogen deposition from CAFO lagoons. The estimated total emission from livestock is 134,000 t NH 3 yr -1 , 73% of which originates from the Coastal Plain. Stronger waste management and emission standards for CAFOs, particularly those on the Coastal Plain nearest to sensitive water bodies

  3. Effect of argon addition into oxygen atmosphere on YBCO thin films deposition

    International Nuclear Information System (INIS)

    Mozhaev, P. B.; Borisenko, I. V.; Ovsyannikov, G. A.; Kuehle, A.; Bindslev-Hansen, J.; Johannes, L.; Skov, J. L.

    2002-01-01

    Multicomponent nature of the YBa 2 Cu 3 O x (YBCO) high-temperature superconductor makes difficult fabrication of smooth thin films: every local deviation from stoichiometry can result in seeding of a non-superconducting oxide particle. High density of such particles on typical YBCO thin film surface, however, presumes overall non-stoichiometry of the film. Such an effect can result from (i) non-uniform material transport from target to substrate, and (ii) re-evaporation or re-sputtering from the growing film surface. The first reason is more usual for laser ablation deposition technique, the second is typical for long sputtering deposition processes. Substitution of oxygen with argon in the deposition atmosphere improves surface quality of YBCO thin films deposited both by laser ablation and DC-sputtering at high pressure techniques. In the first case, the ablated species are scattered different ways in the oxygen atmosphere. Addition of argon decreases the inelastic scattering of barium; the proper part of Ar in the deposition atmosphere makes scattering and, hence, transport of all atoms uniform. The YBCO films deposited by DC-sputtering at high pressure technique are Ba-deficient also, but the reason is re-sputtering of Ba from the growing film as a result of negative oxygen ions bombardment. Such bombardment can lead also to chemical interaction of the deposited material with the substrate, as in the case of deposition of YBCO thin film on the CeO 2 buffer layer on sapphire. Substitution of oxygen with argon not only suppresses ion bombardment of the film, but also increases discharge stability due to presence of positive Ar + ions. The limiting factor of argon substitution is sufficient oxygenation of the growing oxide film. When oxygen partial pressure is too small, the superconducting quality of the YBCO thin film decreases and such a decrease cannot be overcome by prolonged oxygenation after deposition. (Authors)

  4. Toward Synchronous Evaluation of Source Apportionments for Atmospheric Concentration and Deposition of Sulfate Aerosol Over East Asia

    Science.gov (United States)

    Itahashi, S.

    2018-03-01

    Source apportionments for atmospheric concentration, dry deposition, and wet deposition of sulfate aerosol (SO42-) were synchronously evaluated over East Asia, a main source of anthropogenic sulfur dioxide (SO2) emissions. Estimating dry deposition was difficult owing to the difficulty of measuring deposition velocity directly; therefore, sensitivity simulations using two dry deposition schemes were conducted. Moreover, sensitivity simulations for different emission inventories, the largest uncertainty source in the air quality model, were also conducted. In total, four experimental settings were used. Model performance was verified for atmospheric concentration and wet deposition using a ground-based observation network in China, Korea, and Japan, and all four model settings captured the observations. The underestimation of wet deposition over China was improved by an adjusted approach that linearly scaled the modeled precipitation values to observations. The synchronous evaluation of source apportionments for atmospheric concentration and dry and wet deposition showed the dominant contribution of anthropogenic emissions from China to the atmospheric concentration and deposition in Japan. The contributions of emissions from volcanoes were more important for wet deposition than for atmospheric concentration. Differences in the dry deposition scheme and emission inventory did not substantially influence the relative ratio of source apportionments over Japan. Because the dry deposition was more attributed to local factors, the differences in dry deposition may be an important determinant of the source contributions from China to Japan. Verification of these findings, including the dry deposition velocity, is necessary for better understanding of the behavior of sulfur compound in East Asia.

  5. Wet and Dry Atmospheric Mercury Deposition Accumulates in Watersheds of the Northeastern United States

    Science.gov (United States)

    Boyer, E. W.; Grant, C.; Grimm, J.; Drohan, P. J.; Bennett, J.; Lawler, D.

    2013-12-01

    Mercury emissions to the atmosphere from coal-fired power plants and other sources such as waste incineration can be deposited to landscapes in precipitation and in dry fallout. Some mercury reaches watersheds and streams, where it can accumulate in sediments and biota. Human exposure to mercury occurs primarily through fish consumption, and currently mercury fish eating advisories are in place for many of the streams and lakes in the state. Here, we explored mercury in air, soils, water, and biota. To quantify atmospheric mercury deposition, we measured both wet and dry mercury deposition at over 10 locations in Pennsylvania, from which we present variation in mercury deposition and initial assessments of factors affecting the patterns. Further, we simulated mercury deposition at unmonitored locations in Pennsylvania and the northeastern United States over space and time with a high-resolution modeling technique that reflects storm tracks and air flow patterns. To consider mercury accumulation in watersheds, we collected data on soil mercury concentrations in a set of soil samples, and collected baseline data on mercury in streams draining 35 forested watersheds across Pennsylvania, spanning gradients of atmospheric deposition, climate and geology. Mercury concentrations were measured in stream water under base-flow conditions, in streambed sediments, aquatic mosses, and in fish tissues from brook trout. Results indicate that wet and dry atmospheric deposition is a primary source of mercury that is accumulating in watersheds of Pennsylvania and the northeastern United States.

  6. Atmospheric deposition of polycyclic aromatic hydrocarbons (PAHs) in Shanghai: the spatio-temporal variation and source identification

    Science.gov (United States)

    Cheng, Chen; Bi, Chunjuan; Wang, Dongqi; Yu, Zhongjie; Chen, Zhenlou

    2018-03-01

    This study investigated the dry and wet deposition fluxes of atmospheric polycyclic aromatic hydrocarbons (PAHs) in Shanghai, China. The flux sources were traced based on composition and spatio-temporal variation. The results show that wet deposition concentrations of PAHs ranged from 0.07 to 0.67 mg·L-1 and were correlated with temperature ( P<0.05). Dry deposition of PAHs concentrations ranged from 3.60-92.15 mg·L-1 and were higher in winter and spring than in summer and autumn. The annual PAH average fluxes were 0.631 mg·m-2·d-1 and 4.06 mg·m-2·d-1 for wet and dry deposition, respectively. The highest wet deposition of PAH fluxes was observed in summer, while dry deposition fluxes were higher in winter and spring. Atmospheric PAHs were deposited as dry deposition in spring and winter, yet wet deposition was the dominant pathway during summer. Total atmospheric PAH fluxes were higher in the northern areas than in the southern areas of Shanghai, and were also observed to be higher in winter and spring. Annual deposition of atmospheric PAHs was about 10.8 t in across all of Shanghai. Wet deposition of PAHs was primarily composed of two, three, or four rings, while dry deposition of PAHs was composed of four, five, or six rings. The atmospheric PAHs, composed of four, five, or six rings, primarily existed in the form of particulates. Coal combustion and vehicle emissions were the dominant sources of PAH in the observed area of downtown Shanghai. In suburban areas, industrial pollution, from sources such as coke oven, incinerator, and oil fired power plant, was as significant as vehicle emissions in contributing to the deposition of PAHs.

  7. Two dimensional radial gas flows in atmospheric pressure plasma-enhanced chemical vapor deposition

    Science.gov (United States)

    Kim, Gwihyun; Park, Seran; Shin, Hyunsu; Song, Seungho; Oh, Hoon-Jung; Ko, Dae Hong; Choi, Jung-Il; Baik, Seung Jae

    2017-12-01

    Atmospheric pressure (AP) operation of plasma-enhanced chemical vapor deposition (PECVD) is one of promising concepts for high quality and low cost processing. Atmospheric plasma discharge requires narrow gap configuration, which causes an inherent feature of AP PECVD. Two dimensional radial gas flows in AP PECVD induces radial variation of mass-transport and that of substrate temperature. The opposite trend of these variations would be the key consideration in the development of uniform deposition process. Another inherent feature of AP PECVD is confined plasma discharge, from which volume power density concept is derived as a key parameter for the control of deposition rate. We investigated deposition rate as a function of volume power density, gas flux, source gas partial pressure, hydrogen partial pressure, plasma source frequency, and substrate temperature; and derived a design guideline of deposition tool and process development in terms of deposition rate and uniformity.

  8. Atmospheric pulsed laser deposition of plasmonic nanoparticle films of silver with flowing gas and flowing atmospheric plasma

    Science.gov (United States)

    Khan, T. M.; Pokle, A.; Lunney, J. G.

    2018-04-01

    Two methods of atmospheric pulsed laser deposition of plasmonic nanoparticle films of silver are described. In both methods the ablation plume, produced by a 248 nm, 20 ns excimer laser in gas, is strongly confined near the target and forms a nanoparticle aerosol. For both the flowing gas, and the atmospheric plasma from a dielectric barrier discharge plasma source, the aerosol is entrained in the flow and carried to a substrate for deposition. The nanoparticle films produced by both methods were examined by electron microscopy and optical absorption spectroscopy. With plasma assistance, the deposition rate was significantly enhanced and the film morphology altered. With argon gas, isolated nanoparticles of 20 nm size were obtained, whereas in argon plasma, the nanoparticles are aggregated in clusters of 90 nm size. Helium gas also leads to the deposition of isolated nanoparticles, but with helium plasma, two populations of nanoparticles are observed: one of rounded particles with a mean size of 26 nm and the other of faceted particles with a mean size 165 nm.

  9. Atmospheric deposition of radioactive cesium (137Cs) associated with dust events in East Asia

    International Nuclear Information System (INIS)

    Fujiwara, H.

    2010-01-01

    Since the cessation of atmospheric nuclear testing in 1980, there has been no known serious atmospheric contamination by radioactive cesium (sup(137)Cs) apart from the Chernobyl nuclear reactor accident in 1986. There now remain only small amounts of anthropogenic radionuclides in the atmosphere that can be directly related to past testing. However, sup(137)Cs is still regularly found in atmospheric deposition samples in Japan. In this study, we analyzed sup(137)Cs monitoring data, meteorological data, and field survey results to investigate the recent transport and deposition of sup(137)Cs associated with dust phenomena. Monthly records of nationwide sup(137)Cs deposition in Japan during the 1990s show a consistent seasonal variation, with higher levels of deposition occurring in spring. In March 2002, an unexpectedly high amount of sup(137)Cs was deposited in the northwestern coastal area of Japan at the same time as an Asian dust event was observed. Analysis of land-based weather data showed that sandstorms and other dust-raising phenomena also occurred in March 2002 over areas of Mongolia and northeastern China where grassland and shrubs predominated. Furthermore, radioactivity measurements showed sup(137)Cs enrichment in the surface layer of grassland soils in the areas affected by these sandstorms. These results suggest that grasslands are potential sources of sup(137)Cs-bearing dust. Continued desertification of the East Asian continent in response to recent climate change can be expected to result in an increase in sup(137)Cs-bearing soil particles in the atmosphere, and their subsequent re-deposition in Japan. However, soil dust is also raised around Japanese monitoring sites by the strong winds that are common in Japan in spring, and this local dust might also contribute to sup(137)Cs deposition in Japan. To estimate the relative contributions of local and distant dust events to the total sup(137)Cs deposition, we monitored deposition of mineral particles

  10. Dispersion, deposition and resuspension of atmospheric contaminants

    International Nuclear Information System (INIS)

    Anon.

    1985-01-01

    The following topics are discussed: dry deposition, oil shale fugitive air emissions, particle resuspension and translocation, theoretical studies and applications, and processing of emissions by clouds and precipitation. The concentration of contaminant species in air is governed by the rate of input from sources, the rate of dilution or dispersion as a result of air turbulence, and the rate of removal to the surface by wet and dry deposition processes. Once on the surface, contaminants also may be resuspended, depending on meteorological and surface conditions. An understanding of these processes is necessary for accurate prediction of exposures of hazardous or harmful contaminants to humans, animals, and crops. In the field, plume dispersion and plume depletion by dry deposition were studied by the use of tracers. Dry deposition was investigated for particles of both respiration and inhalation interest. Complementary dry deposition studies of particles to rock canopies were conducted under controlled conditions in a wind tunnel. Because of increasing concern about hazardous, organic gases in the atmosphere some limited investigations of the dry deposition of nitrobenzene to a lichen mat were conducted in a stirred chamber. Resuspension was also studied using tracers and contaminated surfaces and in the wind tunnel. The objective of the resuspension studies was to develop and verify models for predicting the airborne concentrations of contaminants over areas with surface contamination, develop resuspension rate predictors for downwind transport, and develop predictors for resuspension input to the food chain. These models will be of particular relevance to the evaluation of deposition and resuspension of both radionuclides and chemical contaminants

  11. Mosses as an integrating tool for monitoring PAH atmospheric deposition: comparison with total deposition and evaluation of bioconcentration factors. A year-long case-study.

    Science.gov (United States)

    Foan, Louise; Domercq, Maria; Bermejo, Raúl; Santamaría, Jesús Miguel; Simon, Valérie

    2015-01-01

    Polycyclic aromatic hydrocarbon (PAH) atmospheric deposition was evaluated at a remote site in Northern Spain using moss biomonitoring with Hylocomium splendens (Hedw.) Schimp., and by measuring the total deposition fluxes of PAHs. The year-long study allowed seasonal variations of PAH content in mosses to be observed, and these followed a similar trend to those of PAH fluxes in total deposition. Generally, atmospheric deposition of PAHs is greater in winter than in summer, due to more PAH emissions from domestic heating, less photoreactivity of the compounds, and intense leaching of the atmosphere by wet deposition. However, fractionation of these molecules between the environmental compartments occurs: PAH fluxes in total deposition and PAH concentrations in mosses are correlated with their solubility (r=0.852, pPAH fluxes can be estimated with moss biomonitoring data if the bioconcentration or 'enriching' factors are known. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. Hg concentrations from Late Triassic and Early Jurassic sedimentary rocks: first order similarities and second order depositional and diagenetic controls

    Science.gov (United States)

    Yager, J. A.; West, A. J.; Bergquist, B. A.; Thibodeau, A. M.; Corsetti, F. A.; Berelson, W.; Bottjer, D. J.; Rosas, S.

    2016-12-01

    Mercury concentrations in sediments have recently gained prominence as a potential tool for identifying large igneous province (LIP) volcanism in sedimentary records. LIP volcanism coincides with several mass extinctions during the Phanerozoic, but it is often difficult to directly tie LIP activity with the record of extinction in marine successions. Here, we build on mercury concentration data reported by Thibodeau et al. (Nature Communications, 7:11147, 2016) from the Late Triassic and Early Jurassic of New York Canyon, Nevada, USA. Increases in Hg concentrations in that record were attributed to Central Atlantic Magmatic Province (CAMP) activity in association with the end-Triassic mass extinction. We expand the measured section from New York Canyon and report new mercury concentrations from Levanto, Peru, where dated ash beds provide a discrete chronology, as well as St. Audrie's Bay, UK, a well-studied succession. We correlate these records using carbon isotopes and ammonites and find similarities in the onset of elevated Hg concentrations and Hg/TOC in association with changes in C isotopes. We also find second order patterns that differ between sections and may have depositional and diagenetic controls. We will discuss these changes within a sedimentological framework to further understand the controls on Hg concentrations in sedimentary records and their implications for past volcanism.

  13. Atmospheric deposition, CO2, and change in the land carbon sink

    DEFF Research Database (Denmark)

    Martinez-Fernandez, Cristina; Vicca, Sara; Janssens, Ivan A.

    2017-01-01

    Concentrations of atmospheric carbon dioxide (CO2) have continued to increase whereas atmospheric deposition of sulphur and nitrogen has declined in Europe and the USA during recent decades. Using time series of flux observations from 23 forests distributed throughout Europe and the USA, and gene...... show the need to include the effects of changing atmospheric composition, beyond CO2, to assess future dynamics of carbon-climate feedbacks not currently considered in earth system/climate modelling....

  14. Worldwide dispersion and deposition of radionuclides produced in atmospheric tests.

    Science.gov (United States)

    Bennett, Burton G

    2002-05-01

    Radionuclides produced in atmospheric nuclear tests were widely dispersed in the global environment. From the many measurements of the concentrations in air and the deposition amounts, much was learned of atmospheric circulation and environmental processes. Based on these results and the reported fission and total yields of individual tests, it has been possible to devise an empirical model of the movement and residence times of particles in the various atmospheric regions. This model, applied to all atmospheric weapons tests, allows extensive calculations of air concentrations and deposition amounts for the entire range of radionuclides produced throughout the testing period. Especially for the shorter-lived fission radionuclides, for which measurement results at the time of the tests are less extensive, a more complete picture of levels and isotope ratios can be obtained, forming a basis for improved dose estimations. The contributions to worldwide fallout can be inferred from individual tests, from tests at specific sites, or by specific countries. Progress was also made in understanding the global hydrological and carbon cycles from the tritium and 14C measurements. A review of the global measurements and modeling results is presented in this paper. In the future, if injections of materials into the atmosphere occur, their anticipated motions and fates can be predicted from the knowledge gained from the fallout experience.

  15. Watershed-scale changes in terrestrial nitrogen cycling during a period of decreased atmospheric nitrate and sulfur deposition

    Science.gov (United States)

    Sabo, Robert D.; Scanga, Sara E.; Lawrence, Gregory B.; Nelson, David M.; Eshleman, Keith N.; Zabala, Gabriel A.; Alinea, Alexandria A.; Schirmer, Charles D.

    2016-01-01

    Recent reports suggest that decreases in atmospheric nitrogen (N) deposition throughout Europe and North America may have resulted in declining nitrate export in surface waters in recent decades, yet it is unknown if and how terrestrial N cycling was affected. During a period of decreased atmospheric N deposition, we assessed changes in forest N cycling by evaluating trends in tree-ring δ15N values (between 1980 and 2010; n = 20 trees per watershed), stream nitrate yields (between 2000 and 2011), and retention of atmospherically-deposited N (between 2000 and 2011) in the North and South Tributaries (North and South, respectively) of Buck Creek in the Adirondack Mountains, USA. We hypothesized that tree-ring δ15N values would decline following decreases in atmospheric N deposition (after approximately 1995), and that trends in stream nitrate export and retention of atmospherically deposited N would mirror changes in tree-ring δ15N values. Three of the six sampled tree species and the majority of individual trees showed declining linear trends in δ15N for the period 1980–2010; only two individual trees showed increasing trends in δ15N values. From 1980 to 2010, trees in the watersheds of both tributaries displayed long-term declines in tree-ring δ15N values at the watershed scale (R = −0.35 and p = 0.001 in the North and R = −0.37 and p <0.001 in the South). The decreasing δ15N trend in the North was associated with declining stream nitrate concentrations (−0.009 mg N L−1 yr−1, p = 0.02), but no change in the retention of atmospherically deposited N was observed. In contrast, nitrate yields in the South did not exhibit a trend, and the watershed became less retentive of atmospherically deposited N (−7.3% yr−1, p < 0.001). Our δ15N results indicate a change in terrestrial N availability in both watersheds prior to decreases in atmospheric N deposition, suggesting that decreased atmospheric N deposition was not the sole driver of

  16. Atmospheric mercury pollution around a chlor-alkali plant in Flix (NE Spain): an integrated analysis.

    Science.gov (United States)

    Esbrí, José M; López-Berdonces, Miguel Angel; Fernández-Calderón, Sergio; Higueras, Pablo; Díez, Sergi

    2015-04-01

    An integrated analysis approach has been applied to a mercury (Hg) case study on a chlor-alkali plant located in the Ebro River basin, close to the town of Flix (NE Spain). The study focused on atmospheric Hg and its incorporation in soils and lichens close to a mercury cell chlor-alkali plant (CAP), which has been operating since the end of the 19th century. Atmospheric Hg present in the area was characterized by means of seven total gaseous mercury (TGM) surveys carried out from 2007 to 2012. Surveys were carried out by car, walking, and at fixed locations, and covered an area of some 12 km(2) (including the CAP area, the village in which workers live, Flix town, and the Sebes Wildlife Reserve). Finally, an atmospheric Hg dispersion model was developed with ISC-AERMOD software validated by a lichen survey of the area. The results for the atmospheric compartment seem to indicate that the Flix area currently has the highest levels of Hg pollution in Spain on the basis of the extremely high average concentrations in the vicinity of the CAP (229 ng m(-3)). Moreover, the Hg(0) plume affects Flix town center to some extent, with values well above the international thresholds for residential areas. Wet and dry Hg deposition reached its highest values on the banks of the Ebro River, and this contributes to increased soil contamination (range 44-12,900 ng g(-1), average 775 ng g(-1)). A good fit was obtained between anomalous areas indicated by lichens and the dispersion model for 1 year.

  17. Apportioning global and non-global components of mercury deposition through (210)Pb indexing.

    Science.gov (United States)

    Lamborg, Carl H; Engstrom, Daniel R; Fitzgerald, William F; Balcom, Prentiss H

    2013-03-15

    Our previous work has documented a correlation between Hg concentrations and (210)Pb activity measured in wet deposition that might be used to help apportion sources of Hg in precipitation. Here we present the results of a 27-month precipitation collection effort using co-located samplers for Hg and (210)Pb designed to assess this hypothesis. Study sites were located on the east and west coasts of North America, in the continental interior, and on the Florida Peninsula. Relatively high variability in Hg/(210)Pb ratios was found at all sites regionally and seasonally (e.g., overall: 0.99-9.13ngdpm(-1)). The ratio of average volume-weighted Hg concentrations and (210)Pb activities showed consistent trends (higher in impacted area), with Glacier Bay in southeast Alaska, exhibiting the lowest value. Assuming that Glacier Bay represents a benchmark for a site with no regional contribution, we estimate less than 50% of the Hg input was "global" at the Seattle and Florida sites. Differences in Hg/(210)Pb in wet deposition could be due to either a regional/local source contribution of Hg, or a regional/local enhancement in the removal of Hg from the atmosphere (i.e., oxidants), however, this approach is not capable of discerning between these two possibilities. Thus, this method of source apportionment represents an estimate of the maximal amount of Hg contributed by regional sources and may be limited in regions of deep convective mixing. Copyright © 2012 Elsevier B.V. All rights reserved.

  18. Passive sampling for the isotopic fingerprinting of atmospheric mercury

    Science.gov (United States)

    Bergquist, B. A.; MacLagan, D.; Spoznar, N.; Kaplan, R.; Chandan, P.; Stupple, G.; Zimmerman, L.; Wania, F.; Mitchell, C. P. J.; Steffen, A.; Monaci, F.; Derry, L. A.

    2017-12-01

    Recent studies show that there are variations in the mercury (Hg) isotopic signature of atmospheric Hg, which demonstrates the potential for source tracing and improved understanding of atmospheric cycling of Hg. However, current methods for both measuring atmospheric Hg and collecting enough atmospheric Hg for isotopic analyses require expensive instruments that need power and expertise. Additionally, methods for collecting enough atmospheric Hg for isotopic analysis require pumping air through traps for long periods (weeks and longer). Combining a new passive atmospheric sampler for mercury (Hg) with novel Hg isotopic analyses will allow for the application of stable Hg isotopes to atmospheric studies of Hg. Our group has been testing a new passive sampler for gaseous Hg that relies on the diffusion of Hg through a diffusive barrier and adsorption onto a sulphur-impregnated activated carbon sorbent. The benefit of this passive sampler is that it is low cost, requires no power, and collects gaseous Hg for up to one year with linear, well-defined uptake, which allows for reproducible and accurate measurements of atmospheric gaseous Hg concentrations ( 8% uncertainty). As little as one month of sampling is often adequate to collect sufficient Hg for isotopic analysis at typical background concentrations. Experiments comparing the isotopic Hg signature in activated carbon samples using different approaches (i.e. by passive diffusion, by passive diffusion through diffusive barriers of different thickness, by active pumping) and at different temperatures confirm that the sampling process itself does not impose mass-independent fractionation (MIF). However, sampling does result in a consistent and thus correctable mass-dependent fractionation (MDF) effect. Therefore, the sampler preserves Hg MIF with very high accuracy and precision, which is necessary for atmospheric source tracing, and reasonable MDF can be estimated with some increase in error. In addition to

  19. Atmospheric nitrogen deposition in world biodiversity hotspots: the need for a greater global perspective in assessing N deposition impacts

    NARCIS (Netherlands)

    Phoenix, G.K.; Hicks, W.K.; Cinderby, S.; Kuylenstierna, J.C.I.; Stock, W.D.; Dentener, F.J.; Giller, K.E.; Austin, A.T.; Lefroy, R.D.B.; Gimeno, B.S.; Ashmore, M.R.; Ineson, P.

    2006-01-01

    Increased atmospheric nitrogen (N) deposition is known to reduce plant diversity in natural and semi-natural ecosystems, yet our understanding of these impacts comes almost entirely from studies in northern Europe and North America. Currently, we lack an understanding of the threat of N deposition

  20. Effects of atmospheric deposition of pesticides on terrestrial organisms in the Netherlands

    NARCIS (Netherlands)

    Jong FMW de; Luttik R; SEC

    2004-01-01

    At present there is much focus on the atmospheric dispersal of pesticides. However, there is very little known about the effects of atmospheric deposition, especially in terrestrial ecosystems. In the study described here, a start has been made to clarify the possible effects on terrestrial

  1. CO2 deficit in temperate forest soils receiving high atmospheric N-deposition.

    Science.gov (United States)

    Fleischer, Siegfried

    2003-02-01

    Evidence is provided for an internal CO2 sink in forest soils, that may have a potential impact on the global CO2-budget. Lowered CO2 fraction in the soil atmosphere, and thus lowered CO2 release to the aboveground atmosphere, is indicated in high N-deposition areas. Also at forest edges, especially of spruce forest, where additional N-deposition has occurred, the soil CO2 is lowered, and the gradient increases into the closed forest. Over the last three decades the capacity of the forest soil to maintain the internal sink process has been limited to a cumulative supply of approximately 1000 and 1500 kg N ha(-1). Beyond this limit the internal soil CO2 sink becomes an additional CO2 source, together with nitrogen leaching. This stage of "nitrogen saturation" is still uncommon in closed forests in southern Scandinavia, however, it occurs in exposed forest edges which receive high atmospheric N-deposition. The soil CO2 gradient, which originally increases from the edge towards the closed forest, becomes reversed.

  2. Local deposition of mercury in topsoils around coal-fired power plants: is it always true?

    Science.gov (United States)

    Rodriguez Martin, José Antonio; Nanos, Nikos; Grigoratos, Theodoros; Carbonell, Gregoria; Samara, Constantini

    2014-09-01

    Mercury (Hg) is a toxic element that is emitted to the atmosphere through human activities, mainly fossil fuel combustion. Hg accumulations in soil are associated with atmospheric deposition, while coal-burning power plants remain the most important source of anthropogenic mercury emissions. In this study, we analyzed the Hg concentration in the topsoil of the Kozani-Ptolemais basin where four coal-fired power plants (4,065 MW) run to provide 50 % of electricity in Greece. The study aimed to investigate the extent of soil contamination by Hg using geostatistical techniques to evaluate the presumed Hg enrichment around the four power plants. Hg variability in agricultural soils was evaluated using 276 soil samples from 92 locations covering an area of 1,000 km(2). We were surprised to find a low Hg content in soil (range 1-59 μg kg(-1)) and 50 % of samples with a concentration lower than 6 μg kg(-1). The influence of mercury emissions from the four coal-fired power plants on soil was poor or virtually nil. We associate this effect with low Hg contents in the coal (1.5-24.5 μg kg(-1)) used in the combustion of these power plants (one of the most Hg-poor in the world). Despite anthropic activity in the area, we conclude that Hg content in the agricultural soils of the Kozani-Ptolemais basin is present in low concentrations.

  3. Investigation of deposition characteristics and properties of high-rate deposited silicon nitride films prepared by atmospheric pressure plasma chemical vapor deposition

    International Nuclear Information System (INIS)

    Kakiuchi, H.; Nakahama, Y.; Ohmi, H.; Yasutake, K.; Yoshii, K.; Mori, Y.

    2005-01-01

    Silicon nitride (SiN x ) films have been prepared at extremely high deposition rates by the atmospheric pressure plasma chemical vapor deposition (AP-PCVD) technique on Si(001) wafers from gas mixtures containing He, H 2 , SiH 4 and N 2 or NH 3 . A 150 MHz very high frequency (VHF) power supply was used to generate high-density radicals in the atmospheric pressure plasma. Deposition rate, composition and morphology of the SiN x films prepared with various deposition parameters were studied by scanning electron microscopy and Auger electron spectroscopy. Fourier transformation infrared (FTIR) absorption spectroscopy was also used to characterize the structure and the chemical bonding configurations of the films. Furthermore, etching rate with buffered hydrofluoric acid (BHF) solution, refractive index and capacitance-voltage (C-V) characteristics were measured to evaluate the dielectric properties of the films. It was found that effective passivation of dangling bonds and elimination of excessive hydrogen atoms at the film-growing surface seemed to be the most important factor to form SiN x film with a dense Si-N network. The C-V curve of the optimized film showed good interface properties, although further improvement was necessary for use in the industrial metal-insulator-semiconductor (MIS) applications

  4. Deposition velocity of gaseous organic iodine from the atmosphere to rice plants

    International Nuclear Information System (INIS)

    Muramatsu, Yasuyuki; Shigeo-Uchida; Sumiya, Misako; Ohmomo, Yoichiro

    1996-01-01

    To obtain parameter values for the assessment of 129 I transfer from the atmosphere to rice, deposition of CH 3 I to rice plants has been studied. The mass normalized deposition velocity (V D ) of CH 3 I for rough (unhulled) rice was 0.00048 cm 3 g -1 s -1 , which is about 1/300 of that of I 2 . Translocation of iodine, deposited as CH 3 I on leaves and stems, to rice grain was negligibly small. Distribution of iodine between hull and inner part of the grain was found to depend also on the chemical forms of atmospheric iodine to be deposited. The ratio of the iodine distribution in a grain exposed to CH 3 I was as follows: rough rice: brown rice (hulled rice):polished rice = 1.0:0.49:0.38. The distribution ratio in polished grains for CH 3 I exposed rice was about 20 times higher than that for I 2 . 22 refs., 1 fig., 6 tabs

  5. Preparation of CdxHg1-xTe films by the method of vapour-phase epitaxy of HgTe on CdTe substrates with subsequent mutual diffusion

    International Nuclear Information System (INIS)

    Varavin, V.S.; Sidorov, Yu.G.; Remesnik, V.G.; Chikichev, S.I.; Nis, I.E.

    1994-01-01

    Mirror-like HgTe films have been grown on CdTe substrates of various orientations by vapor deposition of HgTe in temperature gradient. Deposition rates fell in the range of 5-12 μm/h. Subsequent annealing has permitted production of Hg 1-x Cd x Te layers about 15 μm in thickness. Canier density in annealed n-type specimens has been found to constitute (1-20)x10 15 cm -3 at carrier mobility of (2-5)x10 4 cm 2 xV -1 xs -1 and in p-type films - (1-5)x10 16 cm -3 and 200-350 cm 2 xV -1 xs -1 (77 K) respectively

  6. Atmospheric Mercury Transport Across Southern Lake Michigan: Influence from the Chicago/Gary Urban Area

    Science.gov (United States)

    Gratz, L. E.; Keeler, G. J.; Dvonch, J. T.

    2008-12-01

    The local and regional impacts of mercury emissions from major urban and industrial areas are critical to quantify in order to further understand mercury cycling in the environment. The Chicago/Gary urban area is one such location in which mercury emissions from industrial sources are significant and regional mercury transport needs to be further examined. Speciated atmospheric mercury was measured in Chicago, IL and Holland, MI from July to November 2007 to better characterize the impact of Chicago/Gary on southwest Michigan. Previous work under the 1994-1995 Lake Michigan Mass Balance Study (LMMBS) indicated that the highest levels of mercury deposition in southwest Michigan occurred with transport from the Chicago/Gary area, particularly with rapid transport where less mercury was deposited close to sources(1). However, at that time it was not possible to measure reactive gas phase mercury (RGM), a highly-soluble form of mercury in industrial emissions that is readily removed from the atmosphere. Since the LMMBS, the development of speciated mercury systems has made it possible to continuously monitor gaseous elemental mercury (Hg0), particulate mercury (HgP), and RGM. These measurements are useful for understanding atmospheric mercury chemistry and differentiating between local and regional source impacts due to the different behaviors of reactive and elemental mercury. Results from 2007 show that, on average, Hg0 and HgP were 1.5 times higher and RGM was 2 times higher in Chicago than in Holland. Mean mercury wet deposition was nearly 3 times higher in Chicago than in Holland. Meteorological analysis indicates that transport across the lake from Chicago/Gary occurred frequently during the study. Additional measurements of O3, SO2, meteorological parameters, event mercury and trace element precipitation samples, and modeled back-trajectories are used to discern regional transport events from local deposition and characterize the impact of the Chicago/Gary urban

  7. Optimizing best management practices to control anthropogenic sources of atmospheric phosphorus deposition to inland lakes.

    Science.gov (United States)

    Weiss, Lee; Thé, Jesse; Winter, Jennifer; Gharabaghi, Bahram

    2018-04-18

    Excessive phosphorus loading to inland freshwater lakes around the globe has resulted in nuisance plant growth along the waterfronts, degraded habitat for cold water fisheries, and impaired beaches, marinas and waterfront property. The direct atmospheric deposition of phosphorus can be a significant contributing source to inland lakes. The atmospheric deposition monitoring program for Lake Simcoe, Ontario indicates roughly 20% of the annual total phosphorus load (2010-2014 period) is due to direct atmospheric deposition (both wet and dry deposition) on the lake. This novel study presents a first-time application of the Genetic Algorithm (GA) methodology to optimize the application of best management practices (BMPs) related to agriculture and mobile sources to achieve atmospheric phosphorus reduction targets and restore the ecological health of the lake. The novel methodology takes into account the spatial distribution of the emission sources in the airshed, the complex atmospheric long-range transport and deposition processes, cost and efficiency of the popular management practices and social constraints related to the adoption of BMPs. The optimization scenarios suggest that the optimal overall capital investment of approximately $2M, $4M, and $10M annually can achieve roughly 3, 4 and 5 tonnes reduction in atmospheric P load to the lake, respectively. The exponential trend indicates diminishing returns for the investment beyond roughly $3M per year and that focussing much of this investment in the upwind, nearshore area will significantly impact deposition to the lake. The optimization is based on a combination of the lowest-cost, most-beneficial and socially-acceptable management practices that develops a science-informed promotion of implementation/BMP adoption strategy. The geospatial aspect to the optimization (i.e. proximity and location with respect to the lake) will help land managers to encourage the use of these targeted best practices in areas that

  8. Meridional transport and deposition of atmospheric 10Be

    Directory of Open Access Journals (Sweden)

    J. Feichter

    2009-01-01

    Full Text Available 10Be concentrations measured in ice cores exhibit larger temporal variability than expected based on theoretical production calculations. To investigate whether this is due to atmospheric transport a general circulation model study is performed with the 10Be production divided into stratospheric, tropospheric tropical, tropospheric subtropical and tropospheric polar sources. A control run with present day 10Be production rate is compared with a run during a geomagnetic minimum. The present 10Be production rate is 4–5 times higher at high latitudes than in the tropics whereas during a period of no geomagnetic dipole field it is constant at all latitudes. The 10Be deposition fluxes, however, show a very similar latitudinal distribution in both the present day and the geomagnetic minimum run indicating that 10Be is well mixed in the atmosphere before its deposition. This is also confirmed by the fact that the contribution of 10Be produced in the stratosphere is dominant (55%–70% and relatively constant at all latitudes. The contribution of stratospheric 10Be is approximately 70% in Greenland and 60% in Antarctica reflecting the weaker stratosphere-troposphere air exchange in the Southern Hemisphere.

  9. Multi-year Surface Deposition of {sup 210}Pb and {sup 210}Po at Lisbon - Atmospheric Depositions of {sup 210}Pb and {sup 210}Po in Lisbon, Portugal

    Energy Technology Data Exchange (ETDEWEB)

    Carvalho, Fernando P.; Oliveira, Joao M.; Alberto, G. [Instituto Superior Tecnico/ Campus Tecnologico e Nuclear, Universidade Tecnica de Lisboa, E.N. 10, 2686-953 Sacavem (Portugal)

    2014-07-01

    The long lived radon daughters {sup 210}Pb and {sup 210}Po were determined in samples of total atmospheric depositions obtained with surface collectors continuously operated during 5 years, near Lisbon. The average annual {sup 210}Pb flux was 66±12 Bq m{sup -2}, and the average annual {sup 210}Po flux was 8±3 Bq m{sup -2}, with an overall {sup 210}Po/{sup 210}Pb activity ratio of 0.15±0.06. Direct determination of the {sup 210}Pb atmospheric flux was compared with the {sup 210}Pb excess determined in soil surface layers along with atmospheric depositions of {sup 137}Cs. The deposition of atmospheric {sup 210}Pb was positively correlated with seasonal rainfall, while {sup 210}Po was mainly originated in soil particles re-suspension throughout the year and also in seasonal forest fires. Unusually high {sup 210}Po/{sup 210}Pb activity ratios, higher than unity, were occasionally recorded in atmospheric depositions and the sources and causes are discussed. Long time-series of {sup 210}Pb and {sup 210}Po deposition fluxes, as presented herein are useful to test and constrain parameters of the atmospheric Global Circulation Models. (authors)

  10. Exchange pattern of gaseous elemental mercury in landfill: mercury deposition under vegetation coverage and interactive effects of multiple meteorological conditions.

    Science.gov (United States)

    Tao, Zhengkai; Liu, Yang; Zhou, Meng; Chai, Xiaoli

    2017-12-01

    Landfill is known as a potential source of atmospheric Hg and an important component of the local or regional atmospheric Hg budget. This study investigated the gaseous elemental Hg surface-air fluxes under differing conditions at a typical municipal solid waste landfill site, highlighting the interactive effects of plant coverage and meteorological conditions. The results indicated that Hg fluxes exhibited a feature represented by diel variation. In particular, Hg deposition was observed under a condition of Kochia sieversiana coverage, whereas emission that occurred after K. sieversiana was removed. Hg emission was the dominant mode under conditions of Setaria viridis coverage and its removal; however, the average Hg emission flux with the S. viridis coverage was nearly four times lower than after its removal. These findings verified that the plant coverage should be a key factor influencing the Hg emission from landfills. In addition, Hg fluxes were correlated positively with solar radiation and air/soil temperature and correlated inversely with relative humidity under all conditions, except K. sieversiana coverage. This suggested that the interactive effects of meteorological conditions and plant coverage played a jointly significant role in the Hg emission from landfills. It was established that K. sieversiana can inhibit Hg emission efficiently, and therefore, it could potentially be suitable for use as a plant-based method to control Hg pollution from landfills.

  11. Intensive atmospheric mercury measurements at Terra Nova Bay in Antarctica during November and December 2000

    Science.gov (United States)

    Sprovieri, F.; Pirrone, N.; Hedgecock, I. M.; Landis, M. S.; Stevens, R. K.

    2002-12-01

    It is well known that due to its long atmospheric residence time, mercury is distributed on a global scale and aeolian transport is believed to be the major contributor to mercury in polar environments. No measurements of reactive gaseous mercury (RGM) at all have ever been performed in the Antarctic before. Hg0(g) concentrations were in the range 0.29 to 2.3 ng m-3, with an average value of 0.9 ± 0.3 ng m-3. RGM was measured using KCl-coated annular denuders and a speciation unit coupled to a TGM analyzer; concentrations ranged from 10.5 to 334 pg m-3, with an average of 116.2 ± 77.8 pg m-3. The Hg0(g) measurements are in good agreement with the few data available for such southerly latitudes. The RGM concentrations are as high as those found in some industrial environments; the high concentrations in the absence of local sources (anthropogenic or natural) show that in situ gas phase oxidation of Hg0 is the most important factor influencing RGM production and therefore also Hg deposition. The toxicity of Hg means that the consequences of high concentrations of oxidized and soluble Hg species depositing in the fragile Antarctic environment could be serious indeed.

  12. Shifts in lake N: P stoichiometry and nutrient limitation driven by atmospheric nitrogen deposition

    Science.gov (United States)

    Elser, J.J.; Andersen, T.; Baron, Jill S.; Bergstrom, A.-K.; Jansson, M.; Kyle, M.; Nydick, K.R.; Steger, L.; Hessen, D.O.

    2009-01-01

    Human activities have more than doubled the amount of nitrogen (N) circulating in the biosphere. One major pathway of this anthropogenic N input into ecosystems has been increased regional deposition from the atmosphere. Here we show that atmospheric N deposition increased the stoichiometric ratio of N and phosphorus (P) in lakes in Norway, Sweden, and Colorado, United States, and, as a result, patterns of ecological nutrient limitation were shifted. Under low N deposition, phytoplankton growth is generally N-limited; however, in high-N deposition lakes, phytoplankton growth is consistently P-limited. Continued anthropogenic amplification of the global N cycle will further alter ecological processes, such as biogeochemical cycling, trophic dynamics, and biological diversity, in the world's lakes, even in lakes far from direct human disturbance.

  13. Preparation and characterization of pulsed laser deposited CdTe thin films at higher FTO substrate temperature and in Ar + O{sub 2} atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Chao; Ming, Zhenxun [College of Materials Science and Engineering, Sichuan University, Chengdu 610064, Sichuan (China); Li, Bing, E-mail: libing70@126.com [College of Materials Science and Engineering, Sichuan University, Chengdu 610064, Sichuan (China); Feng, Lianghuan [College of Materials Science and Engineering, Sichuan University, Chengdu 610064, Sichuan (China); Wu, Judy [Department of Physics and Astronomy, Kansas University, Lawrence 66045 (United States)

    2013-06-20

    Highlights: • CdTe films were deposited by PLD at high substrate temperatures (400 °C, 550 °C). • CdTe films were achieved under the atmosphere (1.2 Torr) of Ar mixed with O{sub 2}. • Deposited CdTe films were cubic phase and had strong (1 0 0) preferred orientation. • Scanning electron microscope (SEM) showed an average grain size of 0.3–0.6 μm. • The ultra-thin film (CdS/PLD-CdTe) solar cell with efficiency of 6.68% was made. -- Abstract: Pulsed laser deposition (PLD) is one of the promising techniques for depositing cadmium telluride (CdTe) thin films. It has been reported that PLD CdTe thin films were almost deposited at the lower substrate temperatures (<300 °C) under vacuum conditions. However, the poor crystallinity of CdTe films prepared in this way renders them not conducive to the preparation of high-efficiency CdTe solar cells. To obtain high-efficiency solar cell devices, better crystallinity and more suitable grain size are needed, which requires the CdTe layer to be deposited by PLD at high substrate temperatures (>400 °C). In this paper, CdTe layers were deposited by PLD (KrF, λ = 248 nm, 10 Hz) at different higher substrate temperatures (T{sub s}). Excellent performance of CdTe films was achieved at higher substrate temperatures (400 °C, 550 °C) under an atmosphere of Ar mixed with O{sub 2} (1.2 Torr). X-ray diffraction analysis confirmed the formation of CdTe cubic phase with a strong (1 0 0) preferential orientation at all substrates temperatures on 60 mJ laser energy. The optical properties of CdTe were investigated, and the band gaps of CdTe films were 1.51 eV and 1.49 eV at substrate temperatures of 400 °C and 550 °C, respectively. Scanning electron microscopy (SEM) showed an average grain size of 0.3–0.6 μm. Thus, under these conditions of the atmosphere of Ar + O{sub 2} (15 Torr) and at the relatively high T{sub s} (500 °C), an thin-film (FTO/PLD-CdS (100 nm)/PLD-CdTe (∼1.5 μm)/HgTe: Cu/Ag) solar cell with an

  14. The Use of Biomonitors to Monitor Atmospheric Deposition of 210Pb

    International Nuclear Information System (INIS)

    Jeran, Z.; Jacimovic, R.

    1998-01-01

    The main source of 210 Pb in the environment is the exhalation of 222 Rn gas from the ground to the atmosphere during the radioactive decay of natural uranium - radium chain. In the atmosphere this radionuclide is rapidly attached to small particles - aerosols, predominantly on those particles below 0.3 mm. The half-life of 210 Pb is longer than the atmospheric residence time of the aerosols on which it resides (1). By sedimentation and washout of aerosols this nuclide is then transferred to the soil or vegetation. The other main sources include burning of fossil fuels and phosphate fertilizers. The usual way to determine the levels of 210 Pb and other radionuclides in the atmosphere is the use of a high volume filter system, which should operate for a long time to collect enough material for analysis. An other approach to determining the outdoor levels of radionuclides is the use of suitable biomonitors such as lichens or mosses. These organisms, although neither evolutionarie nor taxonomically related, have some common characteristics which enable them to be used as monitors for atmospheric pollution. They lack roots and protective organs against the substances derived from the atmosphere (stomata and cuticle) and are very efficient accumulators of atmospheric particulate material and chemical substances such as radionuclides or heavy metals (2). The levels of these substances in lichens and mosses are usually much higher than in air particulates or precipitation and for these reason the analysis is much easier. Another advantage of biomonitors over conventional sampling of air particulates or precipitation is that the collection of lichens or mosses is very cheap therefore allows a very large number of sites to be included in the same survey and permits detailed geographical deposition patterns to be drawn (3). It must be emphasised that concentration data on elements or radionuclides in lichens or mosses represent the relative deposition patterns over a certain

  15. Atmospheric depositions around a heavily industrialized area in a seasonally dry tropical environment of India

    International Nuclear Information System (INIS)

    Singh, Raj Kumar; Agrawal, Madhoolika

    2005-01-01

    Clear and throughfall bulk depositions were collected in the downwind of a highly industrialized region in Sonbhadra district of India to estimate the influence of anthropogenic activities on chemical composition of depositions. Significant spatial and temporal variations in depositions of cations and anions were observed. Depositions were higher near the thermal power stations and coalmines as compared to distantly situated site. Seasonally summer samples showed maximum cation and anion depositions followed by winter and minimum in rainy season. The mean pH of the depositions indicates that rainfall in the area is alkaline. Among the anions, maximum deposition was recorded for SO 4 2- followed by NO 3 - and minimum for Cl - . Among the cations, Ca 2+ deposition was maximum followed by NH 4 + . Na + , K + and Mg 2+ deposition rates showed more or less similar values. The depositions of cations and anions as well as pH were higher in throughfall than clearfall samples. Results of the present study suggest that atmospheric depositions are strongly modified due to thermal power stations and coal mines in the area. - Atmospheric abundance of cations have neutralized the acidity of depositions around a heavily industrialized area in India

  16. Evaluating the Contributions of Atmospheric Deposition of Carbon and Other Nutrients to Nitrification in Alpine Environments

    Science.gov (United States)

    Oldani, K. M.; Mladenov, N.; Williams, M. W.

    2013-12-01

    The Colorado Front Range of the Rocky Mountains contains undeveloped, barren soils, yet in this environment there is strong evidence for a microbial role in increased nitrogen (N) export. Barren soils in alpine environments are severely carbon-limited, which is the main energy source for microbial activity and sustenance of life. It has been shown that atmospheric deposition can contain high amounts of organic carbon (C). Atmospheric pollutants, dust events, and biological aerosols, such as bacteria, may be important contributors to the atmospheric organic C load. In this stage of the research we evaluated seasonal trends in the chemical composition and optical spectroscopic (fluorescence and UV-vis absorbance) signatures of snow, wet deposition, and dry deposition in an alpine environment at Niwot Ridge in the Rocky Mountains of Colorado to obtain a better understanding of the sources and chemical character of atmospheric deposition. Our results reveal a positive trend between dissolved organic carbon concentrations and calcium, nitrate and sulfate concentrations in wet and dry deposition, which may be derived from such sources as dust and urban air pollution. We also observed the presence of seasonally-variable fluorescent components that may be attributed to fluorescent pigments in bacteria. These results are relevant because atmospheric inputs of carbon and other nutrients may influence nitrification in barren, alpine soils and, ultimately, the export of nitrate to alpine watersheds.

  17. Properties of alumina films prepared by metal-organic chemical vapour deposition at atmospheric pressure in hte presence of small amounts of water

    NARCIS (Netherlands)

    Haanappel, V.A.C.; Haanappel, V.A.C.; van Corbach, H.D.; Rem, J.B.; Fransen, T.; Gellings, P.J.

    1995-01-01

    Thin alumina films were deposited on stainless steel, type AISI 304. The deposition process was carried out in nitrogen with low partial pressures of water (0–2.6 × 10−2 kPa (0−0.20 mmHg)) by metal-organic chemical vapour deposition (MOCVD) with aluminium-tri-sec-butoxide (ATSB) as the precursor.

  18. Atmospheric deposition patterns of (210)Pb and (7)Be in Cienfuegos, Cuba.

    Science.gov (United States)

    Alonso-Hernández, Carlos M; Morera-Gómez, Yasser; Cartas-Águila, Héctor; Guillén-Arruebarrena, Aniel

    2014-12-01

    The radiometric composition of bulk deposition samples, collected monthly for one year, February 2010 until January 2011, at a site located in Cienfuegos (22° 03' N, 80° 29' W) (Cuba), are analysed in this paper. Measurement of (7)Be and (210)Pb activity concentrations were carried out in 12 bulk deposition samples. The atmospheric deposition fluxes of (7)Be and (210)Pb are in the range of 13.2-132 and 1.24-8.29 Bq m(-2), and their mean values are: 56.6 and 3.97 Bq m(-2), respectively. The time variations of the different radionuclide have been discussed in relation with meteorological factors and the mean values have been compared to those published in recent literature from other sites located at different latitudes. The annual average flux of (210)Pb and (7)Be were 47 and 700 Bq m(-2) y(-1), respectively. Observed seasonal variations of deposition data are explained in terms of different environmental features. The atmospheric deposition fluxes of (7)Be and (210)Pb were moderately well correlated with precipitation and well correlated with one another. The (210)Pb/(7)Be ratios in the monthly depositions samples varied in the range of 0.05-0.10 and showed a strong correlation with the number of rainy days. Copyright © 2014 Elsevier Ltd. All rights reserved.

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

    International Nuclear Information System (INIS)

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

    2013-01-01

    Highlights: ► Hg and Pb concentration and isotopic compositions traced anthropogenic sources. ► Concentrations and metal loadings of Hg and Pb increased during the smelting period. ► Hg isotopic compositions changed during smelting compared to the pre-smelting period. ► Data indicate mass independent fractionation of Hg isotopes. - Abstract: Concentrations and isotopic compositions of Hg and Pb were measured in a sediment core collected from Lake Ballinger, near Seattle, Washington, USA. Lake Ballinger has been affected by input of metal contaminants emitted from the Tacoma smelter, which operated from 1887 to 1986 and was located about 53 km south of the lake. Concentrations and loadings of Hg and Pb in Lake Ballinger increased by as much as three orders of magnitude during the period of smelting as compared to the pre-smelting period. Concentrations and loadings of Hg and Pb then decreased by about 55% and 75%, respectively, after smelting ended. Isotopic compositions of Hg changed considerably during the period of smelting (δ 202 Hg = −2.29‰ to −0.38‰, mean −1.23‰, n = 9) compared to the pre-smelting period (δ 202 Hg = −2.91‰ to −2.50‰, mean −2.75‰, n = 4). Variations were also observed in 206 Pb/ 207 Pb and 208 Pb/ 207 Pb isotopic compositions during these periods. Data for Δ 199 Hg and Δ 201 Hg indicate mass independent fractionation (MIF) of Hg isotopes in Lake Ballinger sediment during the smelting and post-smelting period and suggest MIF in the ore smelted, during the smelting process, or chemical modification at some point in the past. Negative values for Δ 199 Hg and Δ 201 Hg for the pre-smelting period are similar to those previously reported for soil, peat, and lichen, likely suggesting some component of atmospheric Hg. Variations in the concentrations and isotopic compositions of Hg and Pb were useful in tracing contaminant sources and the understanding of the depositional history of sedimentation in Lake Ballinger

  20. Evidence for the Importance of Atmospheric Nitrogen Deposition to Eutrophic Lake Dianchi, China

    Science.gov (United States)

    Zhan, X.; Bo, Y.; Zhou, F.; Liu, X.; Paerl, H. W.; Shen, J.; Wang, R.; Li, F. R.; Tao, S.; Yanjun, D.; Tang, X.

    2017-12-01

    Elevated atmospheric nitrogen (N) deposition has significantly influenced aquatic ecosystems, especially with regard to their N budgets and phytoplankton growth potentials. Compared to a considerable number of studies on oligotrophic lakes and oceanic waters, little evidence for the importance of N deposition has been generated for eutrophic lakes, even though emphasis has been placed on reducing external N inputs to control eutrophication in these lakes. Our high-resolution observations of atmospheric depositions and riverine inputs of biologically reactive N species into eutrophic Lake Dianchi (the sixth largest freshwater lake in China) shed new light onto the contribution of N deposition to total N loads. Annual N deposition accounted for 15.7% to 16.6% of total N loads under variable precipitation conditions, 2-fold higher than previous estimates (7.6%) for the Lake Dianchi. The proportion of N deposition to total N loads further increased to 27-48% in May and June when toxic blooms of the ubiquitous non-N2 fixing cyanobacteria Microcystis spp. are initiated and proliferate. Our observations reveal that reduced N (59%) contributes a greater amount than oxidized N to total N deposition, reaching 56-83% from late spring to summer. Progress toward mitigating eutrophication in Lake Dianchi and other bloom-impacted eutrophic lakes will be difficult without reductions in ammonia emissions and subsequent N deposition.

  1. Atmospheric nitrogen deposition budget in a subtropical hydroelectric reservoir (Nam Theun II case study, Lao PDR)

    Science.gov (United States)

    Adon, Marcellin; Galy-Lacaux, Corinne; Serça, Dominique; Guerin, Frederic; Guedant, Pierre; Vonghamsao, Axay; Rode, Wanidaporn

    2016-04-01

    With 490 km² at full level of operation, Nam Theun 2 (NT2) is one of the largest hydro-reservoir in South East Asia. NT2 is a trans-basin hydropower project that diverts water from the Nam Theun river (a Mekong tributary) to the Xe Ban Fai river (another Mekong tributary). Atmospheric deposition is an important source of nitrogen (N), and it has been shown that excessive fluxes of N from the atmosphere has resulted in eutrophication of many coastal waters. A large fraction of atmospheric N input is in the form of inorganic N. This study presents an estimation of the atmospheric inorganic nitrogen budget into the NT2 hydroelectric reservoir based on a two-year monitoring (July 2010 to July 2012) including gas concentrations and precipitation. Dry deposition fluxes are calculated from monthly mean surface measurements of NH3, HNO3 and NO2 concentrations (passive samplers) together with simulated deposition velocities, and wet deposition fluxes from NH4+ and NO3- concentrations in single event rain samples (automated rain sampler). Annual rainfall amount was 2500 and 3160 mm for the two years. The average nitrogen deposition flux is estimated at 1.13 kgN.ha-1.yr-1 from dry processes and 5.52 kgN.ha-1.yr-1 from wet ones, i.e., an average annual total nitrogen flux of 6.6 kgN.ha-1.yr-1 deposited into the NT2 reservoir. The wet deposition contributes to 83% of the total N deposition. The nitrogen deposition budget has been also calculated over the rain tropical forest surrounding the reservoir. Due to higher dry deposition velocities above forested ecosystems, gaseous dry deposition flux is estimated at 4.0 kgN.ha-1.yr-1 leading to a total nitrogen deposition about 9.5 kgN.ha-1.yr-1. This result will be compared to nitrogen deposition in the African equatorial forested ecosystems in the framework of the IDAF program (IGAC-DEBITS-AFrica).

  2. Atmospheric deposition of nutrients to north Florida rivers: A multivariate statistical analysis. Final report. Master's thesis

    International Nuclear Information System (INIS)

    Fu, J.

    1991-01-01

    Atmospheric nutrient input to the Apalachicola Bay estuary was studied because it has been demonstrated that atmospheric deposition can be a major source of nutrients to eastern U.S. estuaries. Besides the Apalachicola River, the Sopchoppy and the Ochlockonee were also selected for a comparative analysis. Receptor model, absolute principal of component analysis (APCA), and mass balance methods were applied in the study. The results of the study show that nitrogen is probably not a limiting nutrient in the three rivers because their N:P mole ratios are nearly 3 times higher than the Redfield ratio for photosynthesis. The total atmospheric nitrogen depositions in the three river watershed are at least as great as their river fluxes. In the Apalachicola River, the atmospheric source of nitrogen is found to be several times higher than the largest possible input of urban sewage. Atmospheric deposition, therefore, might be the dominant nitrogen source entering the estuary. The results of APCA show that Apalachicola River water is mainly a mixture of components that correspond in their compositions to aged rain, ground water, and fresh rain. Atmospheric nitrate deposition is the result of the air pollution, i.e., acid rain. The studies also show that the annual average deposition of nitrate has a narrow range, mainly from 5.8 to 11.5 kg/ha/yr in most of the NADP sites in the 8 southeastern states. Since all the software and data sets employed in the study are accessible nationwide, the methods could be applied in other watersheds

  3. Distribution and air-sea exchange of mercury (Hg in the Yellow Sea

    Directory of Open Access Journals (Sweden)

    Z. J. Ci

    2011-03-01

    Full Text Available The Yellow Sea, surrounded by East China and the Korea Peninsula, is a potentially important receptor for anthropogenic mercury (Hg emissions from East Asia. However, there is little documentation about the distribution and cycle of Hg in this marine system. During the cruise covering the Yellow Sea in July 2010, gaseous elemental mercury (GEM or Hg(0 in the atmosphere, total Hg (THg, reactive Hg (RHg and dissolved gaseous mercury (DGM, largely Hg(0 in the waters were measured aboard the R/V Kexue III. The mean (±SD concentration of GEM over the entire cruise was 2.61 ± 0.50 ng m−3 (range: 1.68 to 4.34 ng m−3, which were generally higher than other open oceans. The spatial distribution of GEM generally reflected a clear gradient with high levels near the coast of East China and low levels in open waters, suggesting the significant atmospheric Hg outflow from East China. The mean concentration of THg in the surface waters was 1.69 ± 0.35 ng l−1 and the RHg accounted for a considerable fraction of THg (RHg: 1.08 ± 0.28 ng l−1, %RHg/THg = 63.9%. The mean concentration of DGM in the surface waters was 63.9 ± 13.7 pg l−1 and always suggested the supersaturation of Hg(0 in the surface waters with respect to Hg(0 in the atmosphere (the degree of saturation: 7.8 ± 2.3 with a range of 3.6–14.0. The mean Hg(0 flux at the air-sea interface was estimated to be 18.3 ± 11.8 ng m−2 h−1 based on a two-layer exchange model. The high wind speed and DGM levels induced the extremely high Hg(0 emission rates. Measurements at three stations showed no clear vertical patterns of DGM, RHg and THg in the water column. Overall, the elevated Hg levels in the Yellow Sea compared with other open oceans suggested that the human activity has influenced the oceanic Hg cycle downwind of East Asia.

  4. Long-term mercury dynamics in UK soils

    International Nuclear Information System (INIS)

    Tipping, E.; Wadsworth, R.A.; Norris, D.A.; Hall, J.R.; Ilyin, I.

    2011-01-01

    A model assuming first-order losses by evasion and leaching was used to evaluate Hg dynamics in UK soils since 1850. Temporal deposition patterns of Hg were constructed from literature information. Inverse modelling indicated that 30% of 898 rural sites receive Hg only from the global circulation, while in 51% of cases local deposition exceeds global. Average estimated deposition is 16 μg Hg m -2 a -1 to rural soils, 19 μg Hg m -2 a -1 to rural and non-rural soils combined. UK soils currently hold 2490 tonnes of reactive Hg, of which 2140 tonnes are due to anthropogenic deposition, mostly local in origin. Topsoil currently releases 5.1 tonnes of Hg 0 per annum to the atmosphere, about 50% more than the anthropogenic flux. Sorptive retention of Hg in the lower soil exerts a strong control on surface water Hg concentrations. Following decreases in inputs, soil Hg concentrations are predicted to decline over hundreds of years. - Highlights: → Spatial data for mercury in UK soils can be related to past atmospheric deposition. → The residence time of Hg (c. 400 years) depends on gaseous evasion and leaching. → UK soils currently contribute more Hg 0 to the atmosphere than human activities. → Sorption of Hg by deeper soil is a strong control on surface water concentrations. - Atmospherically-deposited anthropogenic mercury, mostly of local origin, has accumulated in UK soils, and is now a significant source of Hg 0 to the global circulation.

  5. [Pollution evaluation and health risk assessment of heavy metals from atmospheric deposition in Lanzhou].

    Science.gov (United States)

    Li, Ping; Xue, Su-Yin; Wang, Sheng-Li; Nan, Zhong-Ren

    2014-03-01

    In order to evaluate the contamination and health risk of heavy metals from atmospheric deposition in Lanzhou, samples of atmospheric deposition were collected from 11 sampling sites respectively and their concentrations of heavy metals were determined. The results showed that the average contents of Cu, Pb, Cd, Cr, Ni, Zn and Mn were 82.22, 130.31, 4.34, 88.73, 40.64, 369.23 and 501.49 mg x kg(-1), respectively. There was great difference among different functional areas for all elements except Mn. According to the results, the enrichment factor score of Mn was close to 1, while the enrichment of Zn, Ni, Cu and Cr was more serious, and Pb and Cd were extremely enriched. The assessment results of geoaccumulation index of potential ecological risk indicated that the pollution of Cd in the atmospheric deposition of Lanzhou should be classified as extreme degree, and that of Cu, Ni, Zn, Pb as between slight and extreme degrees, and Cr as practically uncontaminated. Contaminations of atmospheric dust by heavy metals in October to the next March were more serious than those from April to August. Health risk assessment indicated that the heavy metals in atmospheric deposition were mainly ingested by human bodies through hand-mouth ingestion. The non-cancer risk was higher for children than for adults. The order of non-cancer hazard indexes of heavy metals was Pb > Cr > Cd > Cu > Ni > Zn. The non-cancer hazard indexes and carcinogen risks of heavy metals were both lower than their threshold values, suggesting that they will not harm the health.

  6. Seasonal atmospheric deposition variations of polychlorinated biphenyls (PCBs) and comparison of some deposition sampling techniques.

    Science.gov (United States)

    Birgül, Askın; Tasdemir, Yücel

    2011-03-01

    Ambient air and bulk deposition samples were collected between June 2008 and June 2009. Eighty-three polychlorinated biphenyl (PCB) congeners were targeted in the samples. The average gas and particle PCB concentrations were found as 393 ± 278 and 70 ± 102 pg/m(3), respectively, and 85% of the atmospheric PCBs were in the gas phase. Bulk deposition samples were collected by using a sampler made of stainless steel. The average PCB bulk deposition flux value was determined as 6,020 ± 4,350 pg/m(2) day. The seasonal bulk deposition fluxes were not statistically different from each other, but the summer flux had higher values. Flux values differed depending on the precipitation levels. The average flux value in the rainy periods was 7,480 ± 4,080 pg/m(2) day while the average flux value in dry periods was 5,550 ± 4,420 pg/m(2) day. The obtained deposition values were lower than the reported values given for the urban and industrialized areas, yet close to the ones for the rural sites. The reported deposition values were also influenced by the type of the instruments used. The average dry deposition and total deposition velocity values calculated based on deposition and concentration values were found as 0.23 ± 0.21 and 0.13 ± 0.13 cm/s, respectively.

  7. Atmospheric deposition as a source of carbon and nutrients to an alpine catchment of the Colorado Rocky Mountains

    Science.gov (United States)

    Mladenov, N.; Williams, M. W.; Schmidt, S. K.; Cawley, K.

    2012-08-01

    Many alpine areas are experiencing deglaciation, biogeochemical changes driven by temperature rise, and changes in atmospheric deposition. There is mounting evidence that the water quality of alpine streams may be related to these changes, including rising atmospheric deposition of carbon (C) and nutrients. Given that barren alpine soils can be severely C limited, atmospheric deposition sources may be an important source of C and nutrients for these environments. We evaluated the magnitude of atmospheric deposition of C and nutrients to an alpine site, the Green Lake 4 catchment in the Colorado Rocky Mountains. Using a long-term dataset (2002-2010) of weekly atmospheric wet deposition and snowpack chemistry, we found that volume weighted mean dissolved organic carbon (DOC) concentrations were 1.12 ± 0.19 mg l-1, and weekly concentrations reached peaks as high at 6-10 mg l-1 every summer. Total dissolved nitrogen concentration also peaked in the summer, whereas total dissolved phosphorus and calcium concentrations were highest in the spring. To investigate potential sources of C in atmospheric deposition, we evaluated the chemical quality of dissolved organic matter (DOM) and relationships between DOM and other solutes in wet deposition. Relationships between DOC concentration, fluorescence, and nitrate and sulfate concentrations suggest that pollutants from nearby urban and agricultural sources and organic aerosols derived from sub-alpine vegetation may influence high summer DOC wet deposition concentrations. Interestingly, high DOC concentrations were also recorded during "dust-in-snow" events in the spring, which may reflect an association of DOM with dust. Detailed chemical and spectroscopic analyses conducted for samples collected in 2010 revealed that the DOM in many late spring and summer samples was less aromatic and polydisperse and of lower molecular weight than that of winter and fall samples. Our C budget estimates for the Green Lake 4 catchment

  8. Effects of geographical location and land use on atmospheric deposition of nitrogen in the State of Connecticut

    International Nuclear Information System (INIS)

    Luo, Yuzhou; Yang, Xiusheng; Carley, Robert J.; Perkins, Christopher

    2003-01-01

    High ambient concentrations of tropospheric nitrogen and dry deposition flux were found in urban areas. - A network of eight monitoring stations was established to study the atmospheric nitrogen concentration and deposition in the State of Connecticut. The stations were classified into urban, rural, coastal and inland categories to represent the geographical location and land use characteristics surrounding the monitoring sites. Nitrogen species including nitrate, ammonium, nitric acid vapor and organic nitrogen in the air and precipitation were collected, analyzed and used to infer nitrogen concentrations and dry and wet deposition flux densities for the sampling period from 1997 through 1999, with independently collected meteorological data. Statistical analyses were conducted to evaluate the spatial variations of atmospheric concentration and deposition fluxes of total nitrogen in Connecticut. A slightly higher atmospheric concentration of total nitrogen was observed along the Connecticut coastline of Long Island Sound compared to inland areas, while the differences of nitrogen deposition fluxes were insignificant between coastal and inland sites. The land use characteristics surrounding the monitoring sites had profound effects on the atmospheric nitrogen concentration and dry deposition flux. The ambient nitrogen concentration over the four urban sites was averaged 38.9% higher than that over the rural sites, resulting a 58.0% higher dry deposition flux in these sites compared to their rural counterparts. The local industrial activities and traffic emissions of nitrogen at urban areas had significant effects on the spatial distribution of atmospheric nitrogen concentration and dry deposition flux in the State. Wet and total deposition fluxes appeared to be invariant between the monitoring sites, except for high flux densities measured at Old Greenwich, a monitoring station near to and downwind of the New York and New Jersey industrial complexes

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-12-15

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

  10. Current and future levels of mercury atmospheric pollution on a global scale

    Science.gov (United States)

    Pacyna, Jozef M.; Travnikov, Oleg; De Simone, Francesco; Hedgecock, Ian M.; Sundseth, Kyrre; Pacyna, Elisabeth G.; Steenhuisen, Frits; Pirrone, Nicola; Munthe, John; Kindbom, Karin

    2016-10-01

    An assessment of current and future emissions, air concentrations, and atmospheric deposition of mercury worldwide is presented on the basis of results obtained during the performance of the EU GMOS (Global Mercury Observation System) project. Emission estimates for mercury were prepared with the main goal of applying them in models to assess current (2013) and future (2035) air concentrations and atmospheric deposition of this contaminant. The combustion of fossil fuels (mainly coal) for energy and heat production in power plants and in industrial and residential boilers, as well as artisanal and small-scale gold mining, is one of the major anthropogenic sources of Hg emissions to the atmosphere at present. These sources account for about 37 and 25 % of the total anthropogenic Hg emissions globally, estimated to be about 2000 t. Emissions in Asian countries, particularly in China and India, dominate the total emissions of Hg. The current estimates of mercury emissions from natural processes (primary mercury emissions and re-emissions), including mercury depletion events, were estimated to be 5207 t year-1, which represents nearly 70 % of the global mercury emission budget. Oceans are the most important sources (36 %), followed by biomass burning (9 %). A comparison of the 2035 anthropogenic emissions estimated for three different scenarios with current anthropogenic emissions indicates a reduction of these emissions in 2035 up to 85 % for the best-case scenario. Two global chemical transport models (GLEMOS and ECHMERIT) have been used for the evaluation of future mercury pollution levels considering future emission scenarios. Projections of future changes in mercury deposition on a global scale simulated by these models for three anthropogenic emissions scenarios of 2035 indicate a decrease in up to 50 % deposition in the Northern Hemisphere and up to 35 % in Southern Hemisphere for the best-case scenario. The EU GMOS project has proved to be a very important

  11. Current and future levels of mercury atmospheric pollution on a global scale

    Directory of Open Access Journals (Sweden)

    J. M. Pacyna

    2016-10-01

    Full Text Available An assessment of current and future emissions, air concentrations, and atmospheric deposition of mercury worldwide is presented on the basis of results obtained during the performance of the EU GMOS (Global Mercury Observation System project. Emission estimates for mercury were prepared with the main goal of applying them in models to assess current (2013 and future (2035 air concentrations and atmospheric deposition of this contaminant. The combustion of fossil fuels (mainly coal for energy and heat production in power plants and in industrial and residential boilers, as well as artisanal and small-scale gold mining, is one of the major anthropogenic sources of Hg emissions to the atmosphere at present. These sources account for about 37 and 25 % of the total anthropogenic Hg emissions globally, estimated to be about 2000 t. Emissions in Asian countries, particularly in China and India, dominate the total emissions of Hg. The current estimates of mercury emissions from natural processes (primary mercury emissions and re-emissions, including mercury depletion events, were estimated to be 5207 t year−1, which represents nearly 70 % of the global mercury emission budget. Oceans are the most important sources (36 %, followed by biomass burning (9 %. A comparison of the 2035 anthropogenic emissions estimated for three different scenarios with current anthropogenic emissions indicates a reduction of these emissions in 2035 up to 85 % for the best-case scenario. Two global chemical transport models (GLEMOS and ECHMERIT have been used for the evaluation of future mercury pollution levels considering future emission scenarios. Projections of future changes in mercury deposition on a global scale simulated by these models for three anthropogenic emissions scenarios of 2035 indicate a decrease in up to 50 % deposition in the Northern Hemisphere and up to 35 % in Southern Hemisphere for the best-case scenario. The EU GMOS project has

  12. Electrical properties of MIS devices on CdZnTe/HgCdTe

    Science.gov (United States)

    Lee, Tae-Seok; Jeoung, Y. T.; Kim, Hyun Kyu; Kim, Jae Mook; Song, Jinhan; Ann, S. Y.; Lee, Ji Y.; Kim, Young Hun; Kim, Sun-Ung; Park, Mann-Jang; Lee, S. D.; Suh, Sang-Hee

    1998-10-01

    In this paper, we report the capacitance-voltage (C-V) properties of metal-insulator-semiconductor (MIS) devices on CdTe/HgCdTe by the metalorganic chemical vapor deposition (MOCVD) and CdZnTe/HgCdTe by thermal evaporation. In MOCVD, CdTe layers are directly grown on HgCdTe using the metal organic sources of DMCd and DiPTe. HgCdTe layers are converted to n-type and the carrier concentration, ND is low 1015 cm-3 after Hg-vacancy annealing at 260 degrees Celsius. In thermal evaporation, CdZnTe passivation layers were deposited on HgCdTe surfaces after the surfaces were etched with 0.5 - 2.0% bromine in methanol solution. To investigate the electrical properties of the MIS devices, the C-V measurement is conducted at 80 K and 1 MHz. C-V curve of MIS devices on CdTe/HgCdTe by MOCVD has shown nearly flat band condition and large hysteresis, which is inferred to result from many defects in CdTe layer induced during Hg-vacancy annealing process. A negative flat band voltage (VFB approximately equals -2 V) and a small hysteresis have been observed for MIS devices on CdZnTe/HgCdTe by thermal evaporation. It is inferred that the negative flat band voltage results from residual Te4+ on the surface after etching with bromine in methanol solution.

  13. The linear accumulation of atmospheric mercury by vegetable and grass leaves: Potential biomonitors for atmospheric mercury pollution.

    Science.gov (United States)

    Niu, Zhenchuan; Zhang, Xiaoshan; Wang, Sen; Ci, Zhijia; Kong, Xiangrui; Wang, Zhangwei

    2013-09-01

    One question in the use of plants as biomonitors for atmospheric mercury (Hg) is to confirm the linear relationships of Hg concentrations between air and leaves. To explore the origin of Hg in the vegetable and grass leaves, open top chambers (OTCs) experiment was conducted to study the relationships of Hg concentrations between air and leaves of lettuce (Lactuca sativa L.), radish (Raphanus sativus L.), alfalfa (Medicago sativa L.) and ryegrass (Lolium perenne L.). The influence of Hg in soil on Hg accumulation in leaves was studied simultaneously by soil Hg-enriched experiment. Hg concentrations in grass and vegetable leaves and roots were measured in both experiments. Results from OTCs experiment showed that Hg concentrations in leaves of the four species were significantly positively correlated with those in air during the growth time (p  0.05). Thus, Hg in grass leaves is mainly originated from the atmosphere, and grass leaves are more suitable as potential biomonitors for atmospheric Hg pollution. The effect detection limits (EDLs) for the leaves of alfalfa and ryegrass were 15.1 and 22.2 ng g(-1), respectively, and the biological detection limit (BDL) for alfalfa and ryegrass was 3.4 ng m(-3).

  14. Atmospheric heavy metal deposition in the Copenhagen area

    Energy Technology Data Exchange (ETDEWEB)

    Andersen, A; Hovmand, M F; Johnsen, I

    1978-10-01

    Transport of heavy metals from the atmosphere to the soil and vegetation takes place by dust fall, bulk precipitation, and gas/aerosol adsorption processes. Atmospheric dry and wet deposition of the heavy metals lead, zinc, nickel, vanadium, iron, and copper over the Copenhagen area was measured by sampling in plastic funnels from 17 stations throughout the area for 12 months. Epigeic bryophytes, epiphytic lichen, and topsoil samples were analyzed. A linear correlation between bulk precipitation and heavy metal concentration in lichens and bryophytes was found. An exponential correlation between bulk precipitation and heavy metal concentration in soil was noted. Regional variation of the heavy metal levels in the Copenhagen area was described, and three sub-areas with high metal burdens were distinguished. (10 diagrams, 8 graphs, 13 references, 2 tables)

  15. The effects of atmospheric nitrogen deposition in the Rocky Mountains of Colorado and southern Wyoming, USA-a critical review

    International Nuclear Information System (INIS)

    Burns, Douglas A.

    2004-01-01

    The Rocky Mountains of Colorado and southern Wyoming receive atmospheric nitrogen (N) deposition that ranges from 2 to 7 kg ha -1 yr -1 , and some previous research indicates pronounced ecosystem effects at the highest rates of deposition. This paper provides a critical review of previously published studies on the effects of atmospheric N deposition in the region. Plant community changes have been demonstrated through N fertilization studies, however, N limitation is still widely reported in alpine tundra and subalpine forests of the Front Range, and sensitivity to changes in snow cover alone indicate the importance of climate sensitivity in these ecosystems. Retention of N in atmospheric wet deposition is 3 - concentrations have not been demonstrated, and future trend analyses must consider the role of climate as well as N deposition. Relatively high rates of atmospheric N deposition east of the Divide may have altered nutrient limitation of phytoplankton, species composition of diatoms, and amphibian populations, but most of these effects have been inconclusive to date, and additional studies are needed to confirm hypothesized cause and effect relations. Projected future population growth and energy use in Colorado and the west increase the likelihood that the subtle effects of atmospheric N deposition now evident in the Front Range will become more pronounced and widespread in the future. - The effects of nitrogen deposition will become more evident as growth increases

  16. Atmospheric nitrogen deposition: Revisiting the question of the importance of the organic component

    International Nuclear Information System (INIS)

    Cornell, Sarah E.

    2011-01-01

    The organic component of atmospheric reactive nitrogen plays a role in biogeochemical cycles, climate and ecosystems. Although its deposition has long been known to be quantitatively significant, it is not routinely assessed in deposition studies and monitoring programmes. Excluding this fraction, typically 25-35%, introduces significant uncertainty in the determination of nitrogen deposition, with implications for the critical loads approach. The last decade of rainwater studies substantially expands the worldwide dataset, giving enough global coverage for specific hypotheses to be considered about the distribution, composition, sources and effects of organic-nitrogen deposition. This data collation and meta-analysis highlights knowledge gaps, suggesting where data-gathering efforts and process studies should be focused. New analytical techniques allow long-standing conjectures about the nature and sources of organic N to be investigated, with tantalising indications of the interplay between natural and anthropogenic sources, and between the nitrogen and carbon cycles. - Highlights: → Organic-nitrogen deposition is globally ubiquitous. → Geographic patterns can now be seen in the near-global dataset. → Organic N can be formed through interactions of biogenic and anthropogenic compounds. → Neglecting organic N in deposition assessments increases critical loads uncertainty - Routinely including the organic component of atmospheric deposition (known to be around 25-35% worldwide) would make the understanding and prediction of nitrogen biogeochemistry more robust. This paper makes a preliminary global synthesis based on literature reports.

  17. RF sputtered HgCdTe films for tandem cell applications

    International Nuclear Information System (INIS)

    Wang, S.L.; Lee, S.H.; Gupta, A.; Compaan, A.D.

    2004-01-01

    Polycrystalline Hg 1-x Cd x Te films were investigated for their potential as bottom cells of a CdTe-based tandem solar cell. The films were deposited by RF sputtering from a cold pressed target containing 30% HgTe+70% CdTe. The as-deposited films were highly resistive with (111) preferred orientation and a bandgap of ∝1.0 eV. Various thermal treatment schemes were investigated under different conditions of ambient and temperature to reduce the resistivity. The film properties were analyzed using infrared transmission spectra, energy dispersive X-ray spectra and X-ray diffraction. N doped p-HgCdTe films were also prepared by reactive sputtering in a N 2 /Ar ambient. P-n junction solar cells were fabricated with CdS films as the heterojunction partner. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  18. Atmospheric spatial atomic layer deposition of in-doped ZnO

    NARCIS (Netherlands)

    Illiberi, A.; Scherpenborg, R.; Roozeboom, F.; Poodt, P.

    2014-01-01

    Indium-doped zinc oxide (ZnO:In) has been grown by spatial atomic layer deposition at atmospheric pressure (spatial-ALD). Trimethyl indium (TMIn), diethyl zinc (DEZ) and deionized water have been used as In, Zn and O precursor, respectively. The metal content of the films is controlled in the range

  19. Atmospheric deposition, retention, and stream export of dioxins and PCBs in a pristine boreal catchment

    International Nuclear Information System (INIS)

    Bergknut, Magnus; Laudon, Hjalmar; Jansson, Stina; Larsson, Anna; Gocht, Tilman; Wiberg, Karin

    2011-01-01

    The mass-balance between diffuse atmospheric deposition of organic pollutants, amount of pollutants retained by the terrestrial environment, and levels of pollutants released to surface stream waters was studied in a pristine northern boreal catchment. This was done by comparing the input of atmospheric deposition of polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) and PCBs with the amounts exported to surface waters. Two types of deposition samplers were used, equipped with a glass fibre thimble and an Amberlite sampler respectively. The measured fluxes showed clear seasonality, with most of the input and export occurring during winter and spring flood, respectively. The mass balance calculations indicates that the boreal landscape is an effective sink for PCDD/Fs and PCBs, as 96.0-99.9 % of received bulk deposition was retained, suggesting that organic pollutants will continue to impact stream water in the region for an extended period of time. - Graphical abstract: Display Omitted Highlights: → The fluxes of organic pollutants in a pristine boreal catchment were measured. → Most of the input and export occurred during winter and spring flood. → 96.0-99.9% of received bulk deposition was retained by the landscape. → Organic pollutants will impact boreal stream waters for an extended period of time. - The boreal landscape is effective in retaining diffuse atmospheric deposition of dioxins and PCBs, slowly releasing these pollutants into nearby streams.

  20. Long-term mercury dynamics in UK soils

    Energy Technology Data Exchange (ETDEWEB)

    Tipping, E., E-mail: et@ceh.ac.uk [Centre for Ecology and Hydrology, Lancaster Environment Centre, Library Avenue, Bailrigg, Lancaster LA1 4AP (United Kingdom); Wadsworth, R.A. [Centre for Ecology and Hydrology, Lancaster Environment Centre, Library Avenue, Bailrigg, Lancaster LA1 4AP (United Kingdom); Norris, D.A.; Hall, J.R. [Centre for Ecology and Hydrology, Environment Centre Wales, Deiniol Road, Bangor, Gwynedd LL57 2UW (United Kingdom); Ilyin, I. [Meteorological Synthesizing Centre - East, Krasina pereulok, 16/1, 123056 Moscow (Russian Federation)

    2011-12-15

    A model assuming first-order losses by evasion and leaching was used to evaluate Hg dynamics in UK soils since 1850. Temporal deposition patterns of Hg were constructed from literature information. Inverse modelling indicated that 30% of 898 rural sites receive Hg only from the global circulation, while in 51% of cases local deposition exceeds global. Average estimated deposition is 16 {mu}g Hg m{sup -2} a{sup -1} to rural soils, 19 {mu}g Hg m{sup -2} a{sup -1} to rural and non-rural soils combined. UK soils currently hold 2490 tonnes of reactive Hg, of which 2140 tonnes are due to anthropogenic deposition, mostly local in origin. Topsoil currently releases 5.1 tonnes of Hg{sup 0} per annum to the atmosphere, about 50% more than the anthropogenic flux. Sorptive retention of Hg in the lower soil exerts a strong control on surface water Hg concentrations. Following decreases in inputs, soil Hg concentrations are predicted to decline over hundreds of years. - Highlights: > Spatial data for mercury in UK soils can be related to past atmospheric deposition. > The residence time of Hg (c. 400 years) depends on gaseous evasion and leaching. > UK soils currently contribute more Hg{sup 0} to the atmosphere than human activities. > Sorption of Hg by deeper soil is a strong control on surface water concentrations. - Atmospherically-deposited anthropogenic mercury, mostly of local origin, has accumulated in UK soils, and is now a significant source of Hg{sup 0} to the global circulation.

  1. Atmospheric mercury concentrations observed at ground-based monitoring sites globally distributed in the framework of the GMOS network

    Directory of Open Access Journals (Sweden)

    F. Sprovieri

    2016-09-01

    Full Text Available Long-term monitoring of data of ambient mercury (Hg on a global scale to assess its emission, transport, atmospheric chemistry, and deposition processes is vital to understanding the impact of Hg pollution on the environment. The Global Mercury Observation System (GMOS project was funded by the European Commission (http://www.gmos.eu and started in November 2010 with the overall goal to develop a coordinated global observing system to monitor Hg on a global scale, including a large network of ground-based monitoring stations, ad hoc periodic oceanographic cruises and measurement flights in the lower and upper troposphere as well as in the lower stratosphere. To date, more than 40 ground-based monitoring sites constitute the global network covering many regions where little to no observational data were available before GMOS. This work presents atmospheric Hg concentrations recorded worldwide in the framework of the GMOS project (2010–2015, analyzing Hg measurement results in terms of temporal trends, seasonality and comparability within the network. Major findings highlighted in this paper include a clear gradient of Hg concentrations between the Northern and Southern hemispheres, confirming that the gradient observed is mostly driven by local and regional sources, which can be anthropogenic, natural or a combination of both.

  2. Atmospheric deposition of long-lived Beta radionuclides over the territory of Bulgaria during the last decades

    Energy Technology Data Exchange (ETDEWEB)

    Veleva, B. [National Institute of Meteorology and Hydrology, Bulgarian Academy of Sciences, Sofia (Bulgaria)

    2013-07-01

    The sources of atmospheric radioactivity are discussed and compared. Radon isotopes and their daughters' dominate the natural background of beta activity in the surface air. The man-made radionuclides, much of them beta emitters, started to contaminate regionally and globally the environment after 1940's due to the atmospheric nuclear bomb tests. Additional significant sources of technogenic radionuclides in the atmosphere were nuclear accidents with pronounced examples of Chernobyl and Fukushima. The Bulgarian network for atmospheric radioactivity monitoring has been developing since 1959 in the frame of the state Hydro-meteorological service, now National Institute of Meteorology and Hydrology. It includes daily measurements of aerosol beta activity and deposition immediately and 120h after the sampling. The time and space variations of deposited beta activity, based on long term data records are presented and impact assessment of the different sources is given. The role of precipitation in deposition of radionuclides is evaluated. (author)

  3. Heavy metals in atmospheric surrogate dry deposition

    Science.gov (United States)

    Morselli; Cecchini; Grandi; Iannuccilli; Barilli; Olivieri

    1999-02-01

    This paper describes a methodological approach for the assessment of the amount of surrogate dry deposition of several toxic heavy metals (Cd, Cr, Cu, Ni, Pb, V, Zn) associated with atmospheric particulate matter at ground level. The objectives of the study were twofold: i) the evaluation of several techniques for the digestion of dry deposition samples for trace metal analysis; ii) the comparison of the results from two samplers with different collecting surfaces. A dry solid surface sampler (DRY sampler, Andersen--USA) and a water layer surface sampler (DAS sampler--MTX Italy) were employed. The samples were collected over a one-year period in an urban site of Bologna (northern Italy). A description is given of the complete procedure, from sampling to data elaboration, including sample storage, digestion and analytical methods. According to the results obtained with three different digestion techniques (Teflon bomb, microwave digester and Teflon flask with vapour cooling system), the highest recovery rate was achieved by the Teflon bomb procedure employing an NBS 1648 Standard Reference Material; 90-95% of the elements considered were recovered by dissolution in a pressurized Teflon bomb with an HNO3-HF mixture. Given these results, the technique was adopted for dry deposition sample digestion. On the basis of the amount of heavy metals measured as monthly deposition fluxes (microg/m2), the collecting efficiency of the DAS sampler for a number of elements was found to be as much as two to three times greater than that of the DRY sampler.

  4. Spatial variation in atmospheric nitrogen deposition on low canopy vegetation

    International Nuclear Information System (INIS)

    Verhagen, Rene; Diggelen, Rudy van

    2006-01-01

    Current knowledge about the spatial variation of atmospheric nitrogen deposition on a local scale is limited, especially for vegetation with a low canopy. We measured nitrogen deposition on artificial vegetation at variable distances of local nitrogen emitting sources in three nature reserves in the Netherlands, differing in the intensity of agricultural practices in the surroundings. In the nature reserve located in the most intensive agricultural region nitrogen deposition decreased with increasing distance to the local farms, until at a distance of 1500 m from the local nitrogen emitting sources the background level of 15 kg N ha -1 yr -1 was reached. No such trend was observed in the other two reserves. Interception was considerably lower than in woodlands and hence affected areas were larger. The results are discussed in relation to the prospects for the conservation or restoration of endangered vegetation types of nutrient-poor soil conditions. - Areas with low canopy vegetation are affected over much larger distances by nitrogen deposition than woodlands

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

    Science.gov (United States)

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

    2012-01-01

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

  6. The Effects of Atmospheric Nitrogen Deposition on Terrestrial and Freshwater Biodiversity

    NARCIS (Netherlands)

    Baron, J.S.; Barber, M.; Adams, M.; Dobben, van H.F.

    2014-01-01

    This chapter reports the findings of a Working Group on how atmospheric nitrogen (N) deposition affects both terrestrial and freshwater biodiversity. Regional and global scale impacts on biodiversity are addressed, together with potential indicators. Key conclusions are that: the rates of loss in

  7. Mercury evasion from a boreal peatland shortens the timeline for recovery from legacy pollution.

    Science.gov (United States)

    Osterwalder, Stefan; Bishop, Kevin; Alewell, Christine; Fritsche, Johannes; Laudon, Hjalmar; Åkerblom, Staffan; Nilsson, Mats B

    2017-11-22

    Peatlands are a major source of methylmercury that contaminates downstream aquatic food webs. The large store of mercury (Hg) in peatlands could be a source of Hg for over a century even if deposition is dramatically reduced. However, the reliability of Hg mass balances can be questioned due to missing long-term land-atmosphere flux measurements. We used a novel micrometeorological system for continuous measurement of Hg peatland-atmosphere exchange to derive the first annual Hg budget for a peatland. The evasion of Hg (9.4 µg m -2 yr -1 ) over the course of a year was seven times greater than stream Hg export, and over two times greater than wet bulk deposition to the boreal peatland. Measurements of dissolved gaseous Hg in the peat pore water also indicate Hg evasion. The net efflux may result from recent declines in atmospheric Hg concentrations that have turned the peatland from a net sink into a source of atmospheric Hg. This net Hg loss suggests that open boreal peatlands and downstream ecosystems can recover more rapidly from past atmospheric Hg deposition than previously assumed. This has important implications for future levels of methylmercury in boreal freshwater fish and the estimation of historical Hg accumulation rates from peat profiles.

  8. Atmospheric Deposition of Pb, Zn, Cu, and Cd in Amman, Jordan

    International Nuclear Information System (INIS)

    Momani, K.A.; Jiries, A.G.; Jaradat, Q.M.

    1999-01-01

    Atmospheric samples were collected by high-volume air sampler and dust fall containers during the summer of 1995 at different sites in Amman City, Jordan. Heavy metal contents in settle able (dust fall) as well as in air particulates (suspended) were analyzed by graphite furnace atomic absorption spectrophotometry. The atmospheric concentrations of Zn, Cu, Pb, and Cd were 344, 170, 291, and 3.8 ng/m 3 , respectively. On the other hand, the levels of these elements in dust fall deposition were 505, 94, 74, and 3.1 μg/g, respectively. The fluxes and dry deposition velocities of these heavy metals were determined and compared with the findings of other investigators worldwide. Significant enrichment coefficients of heavy metals in dust fall were observed. The enrichment coefficients were 12.1, 6.1, 11.7, and 1.1 for Zn, Cu, Pb, and Cd, respectively

  9. Atmospheric Nitrogen Deposition and the Properties of Soils in Forests of Vologda Region

    Science.gov (United States)

    Kudrevatykh, I. Yu.; Ivashchenko, K. V.; Ananyeva, N. D.; Ivanishcheva, E. A.

    2018-02-01

    Twenty plots (20 m2 each) were selected in coniferous and mixed forests of the industrial Vologda district and the Vytegra district without developed industries in Vologda region. In March, snow cores corresponding to the snow cover depth were taken on these plots. In August, soil samples from the 0- to 20-cm layer of litter-free soddy-podzolic soil (Albic Retisol (Ochric)) were taken on the same plots in August. The content of mineral nitrogen (Nmin), including its ammonium (NH+ 4) and nitrate (NO- 3) forms, was determined in the snow (meltwater) and soil. The contents of total organic carbon, total nitrogen, and elements (Al, Ca); pH; particle size distribution; and microbiological parameters―carbon of microbial biomass (Cmic) and microbial respiration (MR)―were determined in the soil. The ratio MR/Cmic = qCO2 (specific respiration of microbial biomass, or soil microbial metabolic quotient) was calculated. The content of Nmic in meltwater of two districts was 1.7 mg/L on the average (1.5 and 0.3 mg/L for the NH+ 4 and NO- 3 forms, respectively). The annual atmospheric deposition was 0.6-8.9 kg Nmin/ha, the value of which in the Vologda district was higher than in the Vytegra district by 40%. Reliable correlations were found between atmospheric NH+ 4 depositions and Cmic (-0.45), between NH+ 4 and qCO2 (0.56), between atmospheric NO- 3 depositions and the soil NO- 3 (-0.45), and between NO- 3 and qCO2 (-0.58). The content of atmospheric Nmin depositions correlated with the ratios C/N (-0.46) and Al/Ca (-0.52) in the soil. In forests with the high input of atmospheric nitrogen (>2.0 kg NH+ 4/(ha yr) and >6.4 kg Nmin/(ha yr)), a tendency of decreasing Cmic, C/N, and Al/Ca, as well as increasing qCO2, was revealed, which could be indicative of deterioration in the functioning of microbial community and the chemical properties of the soil.

  10. Analysis of Atmospheric Nitrate Deposition in Lake Tahoe Using Multiple Oxygen Isotopes

    Science.gov (United States)

    McCabe, J. R.; Michalski, G. M.; Hernandez, L. P.; Thiemens, M. H.; Taylor, K.; Kendall, C.; Wankel, S. D.

    2002-12-01

    Lake Tahoe in the Sierra Nevada Mountain Range is world renown for its depth and water clarity bringing 2.2 million visitors per year resulting in annual revenue of \\1.6 billion from tourism. In past decades the lake has suffered from decreased water clarity (from 32 m plate depth to less than 20), which is believed to be largely the result of algae growth initiated by increased nutrient loading. Lake nutrients have also seen a shift from a nitrogen limited to a phosphorous limited system indicating a large increase in the flux of fixed nitrogen. Several sources of fixed nitrogen of have been suggested including surface runoff, septic tank seepage from ground water and deposition from the atmosphere. Bio-available nitrogen in the form of nitrate (NO_{3}$-) is a main component of this system. Recent studies have estimated that approximately 50% of the nitrogen input into the lake is of atmospheric origin (Allison et al. 2000). However, the impact and magnitude of atmospheric deposition is still one of the least understood aspects of the relationship between air and water quality in the Basin (TRPA Threshold Assessment 2002). The utility of stable isotopes as tracers of nitrate reservoirs has been shown in several studies (Bohlke et al. 1997, Kendall and McDonnell 1998, Durka et al. 1994). Stable nitrogen (δ15N) and oxygen (δ18O) isotopes have been implemented in a dual isotope approach to characterize the various nitrate sources to an ecosystem. While δ18O distinguishes between atmospheric and soil sources of nitrate, processes such as denitrification can enrich the residual nitrate in δ18O leaving a misleading atmospheric signature. The benefit of δ15N as a tracer for NO3- sources is the ability to differentiate natural soil, fertilizer, and animal or septic waste, which contain equivalent δ18O values. The recent implementation of multiple oxygen isotopes to measure Δ17O in nitrate has proven to be a more sensitive tracer of atmospheric deposition. The

  11. Atmospheric deposition of selected chemicals and their effect on nonpoint-source pollution in the Twin Cities Metropolitan Area, Minnesota

    Science.gov (United States)

    Brown, R.G.

    1984-01-01

    Atmospheric deposition and subsequent runoff concentrations of total Kjeldahl nitrogen, dissolved nitrite-plus-nitrate nitrogen, total phosphorus, total sulfate (only for atmospheric deposition), total chloride, and total lead were studied from April 1 to October 31, 1980, in one rural and three urban watersheds in the Twin Cities Metropolitan Area, Minnesota. Seasonal patterns of wetfall and dryfall generally were similar for all constituents except chloride in both rural and urban watersheds. Similarity between constituents and between rural and urban watersheds suggested that regional air masses transported from the Gulf of Mexico by frontal storm movements influence seasonal patterns of atmospheric deposition in the metropolitan area. Local influences such as industrial, agricultural, and vehicular air pollutants were found to influence the magnitude or rate of atmospheric deposition rather than the seasonal pattern. Chloride was primarily influenced by northwest frontal storms laden with coastal chloride. Local influences such as dust from road deicing salt dust are thought to have caused an increase in atmospheric chloride during June.

  12. Mercury sedimentation in lakes in western Whatcom County, Washington, USA and its relation to local industrial and municipal atmospheric sources

    Science.gov (United States)

    Paulson, A.J.; Norton, D.

    2008-01-01

    Concentrations of mercury (Hg) were measured in six dated cores from four lakes in western Whatcom County, Washington, USA, that were at various bearings from a chlor-alkali plant, two municipal waste incinerators and a municipal sewage sludge incinerator. The importance of atmospheric emissions of Hg from these local municipal and industrial sources was evaluating by comparing the temporal trends in sedimentation of the lake cores with the emission history of each Hg species and by examining the geographical distribution of Hg sedimentation in relation to the region's primary wind pattern. Local municipal and industrial sources of atmospheric Hg were not responsible for the majority of the Hg in the upper layer of sediments of Whatcom County lakes because of (1) the significant enrichment of Hg in lake sediments prior to emissions of local industrial and municipal sources in 1964, (2) smaller increases in Hg concentrations occurred after 1964, (3) the similarity of maximum enrichments found in Whatcom County lakes to those in rural lakes around the world, (4) the inconsistency of the temporal trends in Hg sedimentation with the local emission history, and (5) the inconsistency of the geographic trends in Hg sedimentation with estimated deposition. Maximum enrichment ratios of Hg in lake sediments between 2 and 3 that are similar to rural areas in Alaska, Minnesota, and New England suggest that global sources of Hg were primarily responsible for increases of Hg in Whatcom County lakes beginning about 1900. ?? 2007 GovernmentEmployee: U.S. Government, Department of Interior, U.S. Geological Survey.

  13. An evaluation of dry deposition from the long range atmospheric dispersion

    International Nuclear Information System (INIS)

    Suh, K.S.; Kim, E.H.; Hwang, W.T.; Han, M.H.; Lee, H.S.; Lee, C.W.

    2003-01-01

    The dry deposition of pollutants released into the atmosphere must be evaluated to estimate the radiological dose of terrestrial plants and foodstuffs in the ecosystem. Especially, the atmospheric dispersion and dry deposition models have been widely developed to predict and minimize the radiological damage for the surrounding environment after the TMI-2 and the Chernobyl accidents. A Lagrangian particle model for the evaluation the long-range dispersion has been firstly developed in Korea since 2001. The particle tracking method was used for the estimation of the concentration distribution of the radioactive materials released into the atmosphere. The model is designed to estimate air concentration and ground deposition at distances up to some thousands of kilometers from the source point in the horizontal direction. The turbulent motion is considered to separate the treatment of particles within the mixing layer and above the mixing layer. Also, the dispersion model is designed to receive the results of the MM5 model being operated by KMA (Korea Meteorological Administration). The test run of the long-range dispersion model has been performed in the area which covered extends from 102.47deg E to 173.34deg E and from 12.27deg N to 53.72deg N in Northeast Asia. The release point of Cs-137 assumed in the east part of the China. The long range dispersion model has been firstly developed to estimate the radiological consequences against a nuclear accident. The model will be supplemented by the comparative study using the data of the ETEX experiments. (author)

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

    Science.gov (United States)

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

    2007-03-01

    Throughfall and bulk precipitation samples were collected for two watersheds at Acadia National Park, Maine, from 3 May to 16 November 2000, to determine which landscape factors affected mercury (Hg) deposition. One of these watersheds, Cadillac Brook, burned in 1947, providing a natural experimental design to study the effects of forest type on deposition to forested watersheds. Sites that face southwest received the highest Hg deposition, which may be due to the interception of cross-continental movement of contaminated air masses. Sites covered with softwood vegetation also received higher Hg deposition than other vegetation types because of the higher scavenging efficiency of the canopy structure. Methyl mercury (MeHg) deposition was not affected by these factors. Hg deposition, as bulk precipitation and throughfall was lower in Cadillac Brook watershed (burned) than in Hadlock Brook watershed (unburned) because of vegetation type and watershed aspect. Hg and MeHg inputs were weighted by season and vegetation type because these two factors had the most influence on deposition. Hg volatilization was not determined. The total Hg deposition via throughfall and bulk precipitation was 9.4 microg/m(2)/year in Cadillac Brook watershed and 10.2 microg/m(2)/year in Hadlock Brook watershed. The total MeHg deposition via throughfall and bulk precipitation was 0.05 microg/m(2)/year in Cadillac Brook watershed and 0.10 microg/m(2)/year in Hadlock Brook watershed.

  15. Ice Core Perspective on Mercury Pollution during the Past 600 Years.

    Science.gov (United States)

    Beal, Samuel A; Osterberg, Erich C; Zdanowicz, Christian M; Fisher, David A

    2015-07-07

    Past emissions of the toxic metal mercury (Hg) persist in the global environment, yet these emissions remain poorly constrained by existing data. Ice cores are high-resolution archives of atmospheric deposition that may provide crucial insight into past atmospheric Hg levels during recent and historical time. Here we present a record of total Hg (HgT) in an ice core from the pristine summit plateau (5340 m asl) of Mount Logan, Yukon, Canada, representing atmospheric deposition from AD 1410 to 1998. The Colonial Period (∼1603-1850) and North American "Gold Rush" (1850-1900) represent minor fractions (8% and 14%, respectively) of total anthropogenic Hg deposition in the record, with the majority (78%) occurring during the 20th Century. A period of maximum HgT fluxes from 1940 to 1975 coincides with estimates of enhanced anthropogenic Hg emissions from commercial sources, as well as with industrial emissions of other toxic metals. Rapid declines in HgT fluxes following peaks during the Gold Rush and the mid-20th Century indicate that atmospheric Hg deposition responds quickly to reductions in emissions. Increasing HgT fluxes from 1993 until the youngest samples in 1998 may reflect the resurgence of Hg emissions from unregulated coal burning and small-scale gold mining.

  16. HgSe(Te)-HgHal2 systems

    International Nuclear Information System (INIS)

    Pan'ko, V.V.; Khudolij, V.A.; Voroshilov, Yu.V.

    1989-01-01

    Using the methods of differential thermal and X-ray phase analyses the character of chemical interaction in the systems HgTe(Se)-HgHal 2 , where Hal is Cl, Br, I, is investigated. Formation of compounds Hg 3 Se 2 Hal 2 , Hg 3 Te 2 Hal 2 , Hg 3 TeCl 4 and Hg 3 TeBr 4 in these systems is established. The phase diagrams of the studied systems are presented. The parameters of elementary cells of the compounds with the unknown structure, as well as their unknown physicochemical properties, are determined

  17. Lichen-based critical loads for atmospheric nitrogen deposition in Western Oregon and Washington Forests, USA

    Energy Technology Data Exchange (ETDEWEB)

    Geiser, Linda H., E-mail: lgeiser@fs.fed.u [US Forest Service Pacific Northwest Region Air Resource Management Program, Siuslaw National Forest, PO Box 1148, Corvallis, OR 97339 (United States); Jovan, Sarah E. [US Forest Service Forest Inventory and Analysis Program, Pacific Northwest Research Station, 620 SW Main St, Suite 400, Portland, OR 97205 (United States); Glavich, Doug A. [US Forest Service Pacific Northwest Region Air Resource Management Program, Siuslaw National Forest, PO Box 1148, Corvallis, OR 97339 (United States); Porter, Matthew K. [Laboratory for Atmospheric Research, Washington State University, Pullman, WA 99164 (United States)

    2010-07-15

    Critical loads (CLs) define maximum atmospheric deposition levels apparently preventative of ecosystem harm. We present first nitrogen CLs for northwestern North America's maritime forests. Using multiple linear regression, we related epiphytic-macrolichen community composition to: 1) wet deposition from the National Atmospheric Deposition Program, 2) wet, dry, and total N deposition from the Communities Multi-Scale Air Quality model, and 3) ambient particulate N from Interagency Monitoring of Protected Visual Environments (IMPROVE). Sensitive species declines of 20-40% were associated with CLs of 1-4 and 3-9 kg N ha{sup -1} y{sup -1} in wet and total deposition. CLs increased with precipitation across the landscape, presumably from dilution or leaching of depositional N. Tight linear correlation between lichen and IMPROVE data suggests a simple screening tool for CL exceedance in US Class I areas. The total N model replicated several US and European lichen CLs and may therefore be helpful in estimating other temperate-forest lichen CLs. - Lichen-based critical loads for N deposition in western Oregon and Washington forests ranged from 3 to 9 kg ha{sup -1} y{sup -1}, increasing with mean annual precipitation.

  18. Uncertainty analysis of atmospheric deposition simulation of radiocesium and radioiodine from Fukushima Daiichi Nuclear Power Plant

    Science.gov (United States)

    Morino, Yu; Ohara, Toshimasa; Yumimoto, Keiya

    2014-05-01

    Chemical transport models (CTM) played key roles in understanding the atmospheric behaviors and deposition patterns of radioactive materials emitted from the Fukushima Daiichi nuclear power plant (FDNPP) after the nuclear accident that accompanied the great Tohoku earthquake and tsunami on 11 March 2011. In this study, we assessed uncertainties of atmospheric simulation by comparing observed and simulated deposition of radiocesium (137Cs) and radioiodine (131I). Airborne monitoring survey data were used to assess the model performance of 137Cs deposition patterns. We found that simulation using emissions estimated with a regional-scale (~500 km) CTM better reproduced the observed 137Cs deposition pattern in eastern Japan than simulation using emissions estimated with local-scale (~50 km) or global-scale CTM. In addition, we estimated the emission amount of 137Cs from FDNPP by combining a CTM, a priori source term, and observed deposition data. This is the first use of airborne survey data of 137Cs deposition (more than 16,000 data points) as the observational constraints in inverse modeling. The model simulation driven by a posteriori source term achieved better agreements with 137Cs depositions measured by aircraft survey and at in-situ stations over eastern Japan. Wet deposition module was also evaluated. Simulation using a process-based wet deposition module reproduced the observations well, whereas simulation using scavenging coefficients showed large uncertainties associated with empirical parameters. The best-available simulation reproduced the observed 137Cs deposition rates in high-deposition areas (≥10 kBq m-2) within one order of magnitude. Recently, 131I deposition map was released and helped to evaluate model performance of 131I deposition patterns. Observed 131I/137Cs deposition ratio is higher in areas southwest of FDNPP than northwest of FDNPP, and this behavior was roughly reproduced by a CTM if we assume that released 131I is more in gas phase

  19. Triple oxygen isotopes indicate urbanization affects sources of nitrate in wet and dry atmospheric deposition

    Science.gov (United States)

    Nelson, David M.; Tsunogai, Urumu; Ding, Dong; Ohyama, Takuya; Komatsu, Daisuke D.; Nakagawa, Fumiko; Noguchi, Izumi; Yamaguchi, Takashi

    2018-05-01

    Atmospheric nitrate deposition resulting from anthropogenic activities negatively affects human and environmental health. Identifying deposited nitrate that is produced locally vs. that originating from long-distance transport would help inform efforts to mitigate such impacts. However, distinguishing the relative transport distances of atmospheric nitrate in urban areas remains a major challenge since it may be produced locally and/or be transported from upwind regions. To address this uncertainty we assessed spatiotemporal variation in monthly weighted-average Δ17O and δ15N values of wet and dry nitrate deposition during one year at urban and rural sites along the western coast of the northern Japanese island of Hokkaido, downwind of the East Asian continent. Δ17O values of nitrate in wet deposition at the urban site mirrored those of wet and dry deposition at the rural site, ranging between ˜ +23 and +31 ‰ with higher values during winter and lower values in summer, which suggests the greater relative importance of oxidation of NO2 by O3 during winter and OH during summer. In contrast, Δ17O values of nitrate in dry deposition at the urban site were lower (+19 - +25 ‰) and displayed less distinct seasonal variation. Furthermore, the difference between δ15N values of nitrate in wet and dry nitrate deposition was, on average, 3 ‰ greater at the urban than rural site, and Δ17O and δ15N values were correlated for both forms of deposition at both sites with the exception of dry deposition at the urban site. These results suggest that, relative to nitrate in wet and dry deposition in rural environments and wet deposition in urban environments, nitrate in dry deposition in urban environments forms from relatively greater oxidation of NO by peroxy radicals and/or oxidation of NO2 by OH. Given greater concentrations of peroxy radicals and OH in cities, these results imply that dry nitrate deposition results from local NOx emissions more so than wet

  20. Soil surface Hg emission flux in coalfield in Wuda, Inner Mongolia, China.

    Science.gov (United States)

    Li, Chunhui; Liang, Handong; Liang, Ming; Chen, Yang; Zhou, Yi

    2018-03-30

    Hg emission flux from various land covers, such as forests, wetlands, and urban areas, have been investigated. China has the largest area of coalfield in the world, but data of Hg flux of coalfields, especially, those with coal fires, are seriously limited. In this study, Hg fluxes of a coalfield were measured using the dynamic flux chamber (DFC) method, coupled with a Lumex multifunctional Hg analyzer RA-915+ (Lumex Ltd., Russia). The results show that the Hg flux in Wuda coalfield ranged from 4 to 318 ng m -2  h -1 , and the average value for different areas varied, e.g., coal-fire area 99 and 177 ng m -2  h -1 ; no coal-fire area 19 and 32 ng m -2  h -1 ; and backfilling area 53 ng m -2  h -1 . Hg continued to be emitted from an underground coal seam, even if there were no phenomena, such as vents, cracks, and smog, of coal fire on the soil surface. This phenomenon occurred in all area types, i.e., coal-fire area, no coal-fire area, and backfilling area, which is universal in Wuda coalfield. Considering that many coalfields in northern China are similar to Wuda coalfield, they may be large sources of atmospheric Hg. The correlations of Hg emission flux with influence factors, such as sunlight intensity, soil surface temperature, and atmospheric Hg content, were also investigated for Wuda coalfield. Graphical abstract ᅟ.

  1. Effectiveness of Emission Controls to Reduce the Atmospheric Concentrations of Mercury.

    Science.gov (United States)

    Castro, Mark S; Sherwell, John

    2015-12-15

    Coal-fired power plants in the United States are required to reduce their emissions of mercury (Hg) into the atmosphere to lower the exposure of Hg to humans. The effectiveness of power-plant emission controls on the atmospheric concentrations of Hg in the United States is largely unknown because there are few long-term high-quality atmospheric Hg data sets. Here, we present the atmospheric concentrations of Hg and sulfur dioxide (SO2) measured from 2006 to 2015 at a relatively pristine location in western Maryland that is several (>50 km) kilometers downwind of power plants in Ohio, Pennsylvania, and West Virginia. Annual average atmospheric concentrations of gaseous oxidized mercury (GOM), SO2, fine particulate mercury (PBM2.5), and gaseous elemental mercury (GEM) declined by 75%, 75%, 43%, and 13%, respectively, and were strongly correlated with power-plant Hg emissions from the upwind states. These results provide compelling evidence that reductions in Hg emissions from power plants in the United States had their intended impact to reduce regional Hg pollution.

  2. Atmospheric deposition of nitrogen to the Baltic Sea in the period 1995–2006

    Directory of Open Access Journals (Sweden)

    J. Bartnicki

    2011-10-01

    Full Text Available The EMEP/MSC-W model has been used to compute atmospheric nitrogen deposition into the Baltic Sea basin for the period of 12 yr: 1995–2006. The level of annual total nitrogen deposition into the Baltic Sea basin has changed from 230 Gg N in 1995 to 199 Gg N in 2006, decreasing 13 %. This value corresponds well with the total nitrogen emission reduction (11 % in the HELCOM Contracting Parties. However, inter-annual variability of nitrogen deposition to the Baltic Sea basin is relatively large, ranging from −13 % to +17 % of the averaged value. It is mainly caused by the changing meteorological conditions and especially precipitation in the considered period. The calculated monthly deposition pattern is similar for most of the years showing maxima in the autumn months October and November. The source allocation budget for atmospheric nitrogen deposition to the Baltic Sea basin was calculated for each year of the period 1997–2006. The main emission sources contributing to total nitrogen deposition are: Germany 18–22 %, Poland 11–13 % and Denmark 8–11 %. There is also a significant contribution from distant sources like the United Kingdom 6–9 %, as well as from the international ship traffic on the Baltic Sea 4–5 %.

  3. Atmospheric transport and deposition of pesticides: An assessment of current knowledge

    DEFF Research Database (Denmark)

    Pul, W.A.J. van; Bidleman, T.F.; Brorström-Lunden, E.

    1999-01-01

    The current knowledge on atmospheric transport and deposition of pesticides is reviewed and discussed by a working group of experts during the Workshop on Fate of pesticides in the atmosphere; implications for risk assessment, held in Driebergen, the Netherlands, 22-24 April, 1998. In general...... in the exchange processes at the interface between air and soil/water/vegetation. In all process descriptions the uncertainty in the physicochemical properties play an important role. Particularly those in the vapour pressure, Henry's law constant and its temperature dependency. More accurate data...

  4. Rapid atmospheric transport and large-scale deposition of recently synthesized plant waxes

    Science.gov (United States)

    Nelson, Daniel B.; Ladd, S. Nemiah; Schubert, Carsten J.; Kahmen, Ansgar

    2018-02-01

    Sedimentary plant wax 2H/1H ratios are important tools for understanding hydroclimate and environmental changes, but large spatial and temporal uncertainties exist about transport mechanisms from ecosystem to sediments. To assess atmospheric pathways, we collected aerosol samples for two years at four locations within a ∼60 km radius in northern Switzerland. We measured n-alkane distributions and 2H/1H ratios in these samples, and from local plants, leaf litter, and soil, as well as surface sediment from six nearby lakes. Increased concentrations and 2H depletion of long odd chain n-alkanes in early summer aerosols indicate that most wax aerosol production occurred shortly after leaf unfolding, when plants synthesize waxes in large quantities. During autumn and winter, aerosols were characterized by degraded n-alkanes lacking chain length preferences diagnostic of recent biosynthesis, and 2H/1H values that were in some cases more than 100‰ higher than growing season values. Despite these seasonal shifts, modeled deposition-weighted average 2H/1H values of long odd chain n-alkanes primarily reflected summer values. This was corroborated by n-alkane 2H/1H values in lake sediments, which were similar to deposition-weighted aerosol values at five of six sites. Atmospheric deposition rates for plant n-alkanes on land were ∼20% of accumulation rates in lakes, suggesting a role for direct deposition to lakes or coastal oceans near similar production sources, and likely a larger role for deposition on land and transport in river systems. This mechanism allows mobilization and transport of large quantities of recently produced waxes as fine-grained material to low energy sedimentation sites over short timescales, even in areas with limited topography. Widespread atmospheric transfer well before leaf senescence also highlights the importance of the isotopic composition of early season source water used to synthesize waxes for the geologic record.

  5. Critical Loads of Atmospheric Nitrogen Deposition for Aquatic Ecosystems in Yosemite and Sequoia and Kings Canyon National Parks

    Science.gov (United States)

    Nanus, L.; Clow, D. W.; Sickman, J. O.

    2016-12-01

    High-elevation aquatic ecosystems in Yosemite (YOSE) and Sequoia and Kings Canyon (SEKI) National Parks are impacted by atmospheric nitrogen (N) deposition associated with local and regional air pollution. Documented effects include elevated surface water nitrate concentrations, increased algal productivity, and changes in diatom species assemblages. Annual wet inorganic N deposition maps, developed at 1-km resolution for YOSE and SEKI to quantify N deposition to sensitive high-elevation ecosystems, range from 1.0 to over 5.0 kg N ha-1 yr-1. Critical loads of N deposition for nutrient enrichment of aquatic ecosystems were quantified and mapped using a geostatistical approach, with N deposition, topography, vegetation, geology, and climate as potential explanatory variables. Multiple predictive models were created using various combinations of explanatory variables; this approach allowed us to better quantify uncertainty and more accurately identify the areas most sensitive to atmospherically deposited N. The lowest critical loads estimates and highest exceedances identified within YOSE and SEKI occurred in high-elevation basins with steep slopes, sparse vegetation, and areas of neoglacial till and talus. These results are consistent with previous analyses in the Rocky Mountains, and highlight the sensitivity of alpine ecosystems to atmospheric N deposition.

  6. Long-Term Simulated Atmospheric Nitrogen Deposition Alters Leaf and Fine Root Decomposition

    Science.gov (United States)

    Atmospheric nitrogen deposition has been suggested to increase forest carbon sequestration across much of the Northern Hemisphere; slower organic matter decomposition could contribute to this increase. At four sugar maple (Acer saccharum)-dominated northern hardwood forests, we p...

  7. Atmospheric particle characterization, distribution, and deposition in Xi'an, Shaanxi Province, Central China

    International Nuclear Information System (INIS)

    Cao Zongze; Yang Yuhua; Lu, Julia; Zhang Chengxiao

    2011-01-01

    Physical characterization and chemical analysis of settled dusts collected in Xi'an from November 2007 to December 2008 show that (1) dust deposition rates ranged from 14.6 to 350.4 g m -2 yr -1 . The average deposition rate (76.7 g m -2 yr -1 ) ranks the 11th out of 56 dust deposition rates observed throughout the world. The coal-burning power was the major particle source; (2) on average (except site 4), ∼10% of the settled dusts having size 70% having size <30 μm; (3) the concentrations for 20 out of 27 elements analyzed were upto 18 times higher than their soil background values in China. With such high deposition rates of dusts that contain elevated levels of toxic elements, actions should be taken to reduce emission and studies are needed to assess the potential impacts of settled particles on surface ecosystem, water resource, and human health in the area. - Research highlights: → High atmospheric dust deposition rate in Xi'an, Shaanxi, China. → Coal-burning power plan being a major source of particulate matter in Xi'an area. → High levels of toxic elements in the settled dusts. → Enrichment of heavy metals (e.g., Pb, Ni, Cu) in fine particles. - Atmospheric dust deposition rate is high and the levels of toxic elements associated with the settled dusts are elevated in Xi'an, Shaanxi, China.

  8. The atmospheric chemical vapour deposition of coatings on glass

    International Nuclear Information System (INIS)

    Sanderson, Kevin David

    1996-01-01

    The deposition of thin films of indium oxide, tin doped indium oxide (ITO) and titanium nitride for solar control applications have been investigated by Atmospheric Chemical Vapour Deposition (APCVD). Experimental details of the deposition system and the techniques used to characterise the films are presented. Results from investigations into the deposition parameters, the film microstructure and film material properties are discussed. A range of precursors were investigated for the deposition of indium oxide. The effect of pro-mixing the vaporised precursor with an oxidant source and the deposition temperature has been studied. Polycrystalline In 2 O 3 films with a resistivity of 1.1 - 3x10 -3 Ω cm were obtained with ln(thd) 3 , oxygen and nitrogen. The growth of ITO films from ln(thd) 3 , oxygen and a range of tin dopants is also presented. The effect of the dopant precursor, the doping concentration, deposition temperature and the effect of additives on film growth and microstructure is discussed. Control over the preferred orientation growth of ITO has been achieved by the addition of acetate species during film growth. Insitu infra-red spectroscopy has been used to identify the gas phase species and identify the species responsible for the film modification. ITO films with a resistivities of 1.5 - 4x10 -4 Ω cm have been achieved. The deposition of titanium nitride by the APCVD of Ti(NMe 2 ) 4 and a mixture of Ti(NMe 2 ) 4 and ammonia is reported. Contamination of the films and pro-reaction between the precursors in the gas phase is discussed, and the synthesis of new precursors for the deposition of titanium nitride is reported. New precursors have been synthesised under anaerobic conditions and characterised by infra-red spectroscopy, 1 H and 13 C NMR, mass spectrometry, thermal gravemetric analysis and three by single crystal X-ray diffraction. Deposition of titanium nitride utilising two new precursors is reported. (author)

  9. Dry deposition of submicron atmospheric aerosol over water surfaces in motion

    International Nuclear Information System (INIS)

    Nevenick, Calec

    2013-01-01

    Whether by chronic or accidental releases, the impact of a nuclear installation on the environment mainly depends on atmospheric transfers; and as the accidents at Chernobyl and Fukushima show, affect the contamination of surfaces and impacts in the medium and long-term on the environment and the population. In this context, this work focuses on the characterization and modeling of dry deposition of submicron aerosols on liquid surfaces in motion such as rivers. Unlike wet deposition which is conditioned by washout and rainout (rain and clouds), dry deposition is a phenomenon that depends entirely on the characteristics of aerosols, receiving surfaces, and air flow. In practice, the evaluation of dry deposition is based on the estimation of flux modeling as the product of particle concentration and deposition velocity which can vary over several orders of magnitude depending on the receiving surfaces (forest, snow, urban, grassland...). This topic is motivated by the virtual non-existence of studies on the mechanisms of dry deposition on continental water systems such as rivers; and respect for submicron aerosols. They have the lowest deposition efficiencies and filtration and the longer residence time in the atmosphere. In addition, they are potentially the most dangerous to living beings because they can penetrate deeper into the airway. Due to the lack of data on the dry deposition of submicron aerosols on a liquid surface in motion, the approach was based on two axes: 1) the acquisition of experimental deposition velocities and 2) the analysis and interpretation of results through modeling. The experiments were performed with uranine aerosols released into the IOA wind tunnel (Interface Ocean Atmosphere) of the Institute for Research on Non Equilibrium Phenomena which is configured to study the coupling between the air flow and water. These experiments have given many dry deposition velocities for different configurations characterized according to wind

  10. Dry deposition of submicron atmospheric aerosol over water surfaces in motion

    International Nuclear Information System (INIS)

    Calec, Nevenick

    2013-01-01

    Whether by chronic or accidental releases, the impact of a nuclear installation on the environment mainly depends on atmospheric transfers; and as the accidents at Chernobyl and Fukushima show, affect the contamination of surfaces and impacts in the medium and long-term on the environment and the population. In this context, this work focuses on the characterization and modeling of dry deposition of submicron aerosols on liquid surfaces in motion such as rivers. Unlike wet deposition which is conditioned by washout and rainout (rain and clouds), dry deposition is a phenomenon that depends entirely on the characteristics of aerosols, receiving surfaces, and air flow. In practice, the evaluation of dry deposition is based on the estimation of flux modeling as the product of particle concentration and deposition velocity which can vary over several orders of magnitude depending on the receiving surfaces (forest, snow, urban, grassland..). This topic is motivated by the virtual non-existence of studies on the mechanisms of dry deposition on continental water systems such as rivers; and respect for submicron aerosols. They have the lowest deposition efficiencies and filtration and the longer residence time in the atmosphere. In addition, they are potentially the most dangerous to living beings because they can penetrate deeper into the airway. Due to the lack of data on the dry deposition of submicron aerosols on a liquid surface in motion, the approach was based on two axes: 1) the acquisition of experimental deposition velocities and 2) the analysis and interpretation of results through modeling. The experiments were performed with uranine aerosols released into the IOA wind tunnel (Interface Ocean Atmosphere) of the Institute for Research on Non Equilibrium Phenomena which is configured to study the coupling between the air flow and water. These experiments have given many dry deposition velocities for different configurations characterized according to wind

  11. Spectroscopic investigation of the Hg-Mn star κ Cnc. I. Choice of parameters of the model atmosphere and determination of the helium abundance

    International Nuclear Information System (INIS)

    Dobrichev, V.M.; Raikova, D.V.; Ryabchikova, T.A.; Topil'skaya, G.P.

    1989-01-01

    It is shown that a blanketed model atmosphere of the Hg-Mn star κ Cnc with T e = 12,800 degree K and log g = 3.7 (Stepien and Muthsam) completely describes the profiles of the lines H α , H γ , and H δ in the spectrum of this star. The synthetic-spectrum method is used to determine the helium abundance in the atmosphere of κ Cnc: He/H = 0.017, this value being almost three times greater than the value obtained earlier for this star by Adelman. The isotope shift of the lines leads to the isotope ratio 3 He/ 4 He = 0.35, and this indicates that there is a process of diffusion separation of the elements in the atmosphere of κ Cnc. 23 refs., 3 figs., 1 tab

  12. Atmospheric deposition of organochlorine contaminants to Galveston Bay, Texas

    Science.gov (United States)

    Park, June-Soo; Wade, Terry L.; Sweet, Stephen

    Atmospheric monitoring of PCBs and chlorinated pesticides (e.g., HCHs, chlordanes, and DDTs) in Galveston Bay was conducted at Seabrook, Texas. Air and wet deposition samples were collected from 2 February 1995 and continued through 6 August 1996. Vapor total PCB ( tPCB) concentrations in air ranged from 0.21 to 4.78 ng m -3 with a dominance of tri-chlorinated PCBs. Dissolved tPCBs in rain ranged from 0.08 to 3.34 ng l -1, with tetra-chlorinated PCBs predominating. The predominant isomers found in air and rain were α- and γ-HCH, α- and γ-chlordanes, 4,4'-DDT, and dieldrin. The concentrations of PCBs and pesticides in the air and rain revealed no clear seasonal trend. Elevated levels of PCBs in the air occurred when temperatures were high and wind came from urban and industrialized areas (S, SW, NW, and W of the site). Concentrations of HCHs were elevated in April, May, and October, perhaps due to local and/or regional applications of γ-HCH (lindane). Other pesticides showed no notable temporal variation. When winds originated from the Gulf of Mexico (southeasterly), lower concentrations of organochlorines were detected in the air. The direct deposition rate (wet+dry) of PCBs to Galveston Bay (6.40 μg m -2 yr -1) was significantly higher than that of pesticides by a factor of 5-10. The net flux from gas exchange estimated for PCBs was from Galveston Bay water to the atmosphere (78 μg m -2 yr -1). Gas exchange of PCBs from bay water to the atmosphere was the dominant flux.

  13. Deposition of aerosols formed by HCDA due to decay heat transport in inner containment atmospheres

    International Nuclear Information System (INIS)

    Vate, J.F. van de

    1976-01-01

    Coupling of decay heat transfer by aerosol-laden inner containment atmospheres with aerosol deposition from such atmospheres leads to useful and simple models for calculation of the time dependence of the aerosol mass concentration. Special attention is given to thermophoretic deposition (dry case) and condensation followed by gravitational deposition (wet case). Attractive features of the models are: 1) coagulation can be omitted and therefore complicated and doubtful calculations on coagulation are avoided, 2) material and particle size of the aerosol are not important for the aerosol decay rate, 3) the aerosol decay rate is related to the decay heat production which is known function of time, and the relevant part of it must be assessed usually for other purposes as well. (orig.) [de

  14. Determination of Hg concentration in gases by PIXE

    Science.gov (United States)

    Dutkiewicz, E.; van Kuijen, W. J. P.; Munnik, F.; Mutsaers, P. H. A.; Rokita, E.; de Voigt, M. J. A.

    1992-05-01

    A method for determination of the concentration of mercury in the gaseous phase is described. In the first step of the method a stable sulphur-mercury complex is formed. For this purpose sulphur is deposited on a filter and the investigated gas flows through the filter. Millipore filters and the deposition of sulphur from Na2S2O3 * 5H2O solution were found to be most suitable. The amount of Hg absorbed on the filter was determined by PIXE or by NAA in the second step of the method. An optimization of proton energy was performed in the PIXE analysis to obtain the maximal signal-to-background ratio. The detection limit of the method, expressed as the minimal amount of Hg which has to flow through the filter equals to 30 and 2 ng for PIXE and NAA techniques, respectively. Applications of the method are also described.

  15. New insight into atmospheric mercury emissions from zinc smelters using mass flow analysis.

    Science.gov (United States)

    Wu, Qingru; Wang, Shuxiao; Hui, Mulin; Wang, Fengyang; Zhang, Lei; Duan, Lei; Luo, Yao

    2015-03-17

    The mercury (Hg) flow paths from three zinc (Zn) smelters indicated that a large quantity of Hg, approximately 38.0-57.0% of the total Hg input, was stored as acid slag in the landfill sites. Approximately 15.0-27.1% of the Hg input was emitted into water or stored as open-dumped slags, and 3.3-14.5% of the Hg input ended in sulfuric acid. Atmospheric Hg emissions, accounting for 1.4-9.6% of the total Hg input, were from both the Zn production and waste disposal processes. Atmospheric Hg emissions from the waste disposal processes accounted for 40.6, 89.6, and 94.6% of the total atmospheric Hg emissions of the three studied smelters, respectively. The Zn production process mainly contributed to oxidized Hg (Hg2+) emissions, whereas the waste disposal process generated mostly elemental Hg (Hg0) emissions. When the emissions from these two processes are considered together, the emission proportion of the Hg2+ mass was 51, 46, and 29% in smelters A, B, and C, respectively. These results indicated that approximately 10.8±5.8 t of atmospheric Hg emissions from the waste disposal process were ignored in recent inventories. Therefore, the total atmospheric Hg emissions from the Zn industry of China should be approximately 50 t.

  16. Contribution of atmospheric nitrogen deposition to diffuse pollution in a typical hilly red soil catchment in southern China.

    Science.gov (United States)

    Shen, Jianlin; Liu, Jieyun; Li, Yong; Li, Yuyuan; Wang, Yi; Liu, Xuejun; Wu, Jinshui

    2014-09-01

    Atmospheric nitrogen (N) deposition is currently high and meanwhile diffuse N pollution is also serious in China. The correlation between N deposition and riverine N export and the contribution of N deposition to riverine N export were investigated in a typical hilly red soil catchment in southern China over a two-year period. N deposition was as high as 26.1 to 55.8kgN/(ha·yr) across different land uses in the studied catchment, while the riverine N exports ranged from 7.2 to 9.6kgN/(ha·yr) in the forest sub-catchment and 27.4 to 30.3kgN/(ha·yr) in the agricultural sub-catchment. The correlations between both wet N deposition and riverine N export and precipitation were highly positive, and so were the correlations between NH4(+)-N or NO3(-)-N wet deposition and riverine NH4(+)-N or NO3(-)-N exports except for NH4(+)-N in the agricultural sub-catchment, indicating that N deposition contributed to riverine N export. The monthly export coefficients of atmospheric deposited N from land to river in the forest sub-catchment (with a mean of 14%) presented a significant positive correlation with precipitation, while the monthly contributions of atmospheric deposition to riverine N export (with a mean of 18.7% in the agricultural sub-catchment and a mean of 21.0% in the whole catchment) were significantly and negatively correlated with precipitation. The relatively high contribution of N deposition to diffuse N pollution in the catchment suggests that efforts should be done to control anthropogenic reactive N emissions to the atmosphere in hilly red soil regions in southern China. Copyright © 2014. Published by Elsevier B.V.

  17. Active moss biomonitoring of trace elements with Sphagnum girgensohnii moss bags in relation to atmospheric bulk deposition in Belgrade, Serbia

    International Nuclear Information System (INIS)

    Anicic, M.; Tasic, M.; Frontasyeva, M.V.; Tomasevic, M.; Rajsic, S.; Mijic, Z.; Popovic, A.

    2009-01-01

    Active biomonitoring with wet and dry moss bags was used to examine trace element atmospheric deposition in the urban area of Belgrade. The element accumulation capability of Sphagnum girgensohnii Russow was tested in relation to atmospheric bulk deposition. Moss bags were mounted for five 3-month periods (July 2005-October 2006) at three representative urban sites. For the same period monthly bulk atmospheric deposition samples were collected. The concentrations of Al, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Cd, and Pb were determined by instrumental neutron activation analyses and atomic absorption spectrometry. Significant accumulation of most elements occurred in the exposed moss bags compared with the initial moss content. High correlations between the elements in moss and bulk deposits were found for V, Cu, As, and Ni. The enrichment factors of the elements for both types of monitor followed the same pattern at the corresponding sites. - Accumulated trace elements in the moss Sphagnum girgensohnii reflect atmospheric deposition

  18. Puff-plume atmospheric deposition model for use at SRP in emergency-response situations

    International Nuclear Information System (INIS)

    Garrett, A.J.; Murphy, C.E. Jr.

    1981-05-01

    An atmospheric transport and diffusion model developed for real-time calculation of the location and concentration of toxic or radioactive materials during an accidental release was improved by including deposition calculations

  19. Atmospheric deposition as a source of carbon and nutrients to barren, alpine soils of the Colorado Rocky Mountains

    Science.gov (United States)

    Mladenov, N.; Williams, M. W.; Schmidt, S. K.; Cawley, K.

    2012-03-01

    Many alpine areas are experiencing intense deglaciation, biogeochemical changes driven by temperature rise, and changes in atmospheric deposition. There is mounting evidence that the water quality of alpine streams may be related to these changes, including rising atmospheric deposition of carbon (C) and nutrients. Given that barren alpine soils can be severely C limited, we evaluated the magnitude and chemical quality of atmospheric deposition of C and nutrients to an alpine site, the Green Lake 4 catchment in the Colorado Rocky Mountains. Using a long term dataset (2002-2010) of weekly atmospheric wet deposition and snowpack chemistry, we found that volume weighted mean dissolved organic carbon (DOC) concentrations were approximately 1.0 mg L-1and weekly concentrations reached peaks as high at 6-10 mg L-1 every summer. Total dissolved nitrogen concentration also peaked in the summer, whereas total dissolved phosphorus and calcium concentrations were highest in the spring. Relationships among DOC concentration, dissolved organic matter (DOM) fluorescence properties, and nitrate and sulfate concentrations suggest that pollutants from nearby urban and agricultural sources and organic aerosols derived from sub-alpine vegetation may influence high summer DOC wet deposition concentrations. Interestingly, high DOC concentrations were also recorded during "dust-in-snow" events in the spring. Detailed chemical and spectroscopic analyses conducted for samples collected in 2010 revealed that the DOM in many late spring and summer samples was less aromatic and polydisperse and of lower molecular weight than that of winter and fall samples and, therefore, likely to be more bioavailable to microbes in barren alpine soils. Bioavailability experiments with different types of atmospheric C sources are needed to better evaluate the substrate quality of atmospheric C inputs. Our C budget estimates for the Green Lake 4 catchment suggest that atmospheric deposition represents an

  20. Interlaboratory model comparisons of atmospheric concentrations with and without deposition

    International Nuclear Information System (INIS)

    Kern, C.D.; Cooper, R.E.

    1978-01-01

    To calculate the dose to the regional and U.S. populations, the pollutant concentration both with and without deposition and the amount of material deposited on the ground and watersheds around such a facility must be known. The following report (Article 50) of this document contains some initial estimates of population exposure from atmospheric effluents. The expertise of laboratories supported by U.S. Department of Energy funds ensures that the latest methods and data are available. Lawrence Livermore Laboratory (LLL) performed regional calculations (out to distances of the order of 200 km from a hypothetical fuel reprocessing plant). The Air Resources Laboratory (ARL) of the National Oceanic and Atmospheric Administration (NOAA), and Battelle Pacific Northwest Laboratories (PNL) performed U.S. scale calculations, and ARL also did the global calculations. Data from a winter and summer period were used to make comparisons of calculations by LLL, ARL, and PNL to determine which model should be used for the final calculations and to determine if a 200-km square area centered on the site would be large enough for dose calculations via the water and food pathways

  1. Atmospheric deposition of methanol over the Atlantic Ocean

    Science.gov (United States)

    Yang, Mingxi; Nightingale, Philip D.; Beale, Rachael; Liss, Peter S.; Blomquist, Byron; Fairall, Christopher

    2013-01-01

    In the troposphere, methanol (CH3OH) is present ubiquitously and second in abundance among organic gases after methane. In the surface ocean, methanol represents a supply of energy and carbon for marine microbes. Here we report direct measurements of air–sea methanol transfer along a ∼10,000-km north–south transect of the Atlantic. The flux of methanol was consistently from the atmosphere to the ocean. Constrained by the aerodynamic limit and measured rate of air–sea sensible heat exchange, methanol transfer resembles a one-way depositional process, which suggests dissolved methanol concentrations near the water surface that are lower than what were measured at ∼5 m depth, for reasons currently unknown. We estimate the global oceanic uptake of methanol and examine the lifetimes of this compound in the lower atmosphere and upper ocean with respect to gas exchange. We also constrain the molecular diffusional resistance above the ocean surface—an important term for improving air–sea gas exchange models. PMID:24277830

  2. Stable isotope evidence for an atmospheric origin of desert nitrate deposits in northern Chile and southern California, U.S.A.

    Science.gov (United States)

    Böhlke, J.K.; Ericksen, G.E.; Revesz, K.

    1997-01-01

    Natural surficial accumulations of nitrate-rich salts in the Atacama Desert, northern Chile, and in the Death Valley region of the Mojave Desert, southern California, are well known, but despite many geologic and geochemical studies, the origins of the nitrates have remained controversial. N and O isotopes in nitrate, and S isotopes in coexisting soluble sulfate, were measured to determine if some proposed N sources could be supported or rejected, and to determine if the isotopic signature of these natural deposits could be used to distinguish them from various types of anthropogenic nitrate contamination that might be found in desert groundwaters. High-grade caliche-type nitrate deposits from both localities have ??15N values that range from -5 to +5???, but are mostly near 0???. Values of ??15N near 0??? are consistent with either bulk atmospheric N deposition or microbial N fixation as major sources of the N in the deposits. ??18O values of those desert nitrates with ??15N near 0??? range from about +31 to + 50??? (V-SMOW), significantly higher than that of atmospheric O2 (+ 23.5???). Such high values of ??18O are considered unlikely to result entirely from nitrification of reduced N, but rather resemble those of modern atmospheric nitrate in precipitation from some other localities. Assuming that limited modern atmospheric isotope data are applicable to the deposits, and allowing for nitrification of co-deposited ammonium, it is estimated that the fraction of the nitrate in the deposits that could be accounted for isotopically by atmospheric N deposition may be at least 20% and possibly as much as 100%. ??34S values are less diagnostic but could also be consistent with atmospheric components in some of the soluble sulfates associated with the deposits. The stable isotope data support the hypothesis that some high-grade caliche-type nitrate-rich salt deposits in some of the Earth's hyperarid deserts represent long-term accumulations of atmospheric deposition

  3. Study of the odd mass transition nuclei: 185Hg, 187Hg, 189Hg and 183Ir

    International Nuclear Information System (INIS)

    Zerrouki, A.

    1979-01-01

    The radioactive decay of 185 Tl, 186 Tl, 187 Tl has been studied on the isotope separator Isocele II working on line with the Orsay synchrocyclotron from Au( 3 He,xn) reactions: the emitted α lines have been measured and the main γ lines belonging to the 187 Tl→ 187 Hg decay have been identified. The 185 Hg, 187 Hg, 189 Hg high spin states have been studied using the following (HI,xn) reactions obtained on the Strasbourg MP Tandem: 168 Er( 24 Mg,xn) 187 Hg, 188 Hg, 166 Er( 24 Mg,xn) 185 Hg, 186 Hg, 157 Gd( 32 S,xn) 184 Hg, 185 Hg, 158 Gd( 32 S,5n) 185 Hg and 175 Lu( 19 F,5n) 189 Hg. The excitation functions are indicated and a high spin level scheme of 189 Hg is proposed: it is compared to the 'quasiparticle + triaxial rotor' model predictions. A level scheme of 183 Ir is proposed from the data collected at Isolde II (CERN) by Dr. SCHUCK: it is analysed within the framework of the same theoretical model used above [fr

  4. Trace-element evidence for the origin of desert varnish by direct aqueous atmospheric deposition

    Science.gov (United States)

    Thiagarajan, Nivedita; Aeolus Lee, Cin-Ty

    2004-07-01

    Smooth rock surfaces in arid environments are often covered with a thin coating of Fe-Mn oxyhydroxides known as desert varnish. It is debated whether such varnish is formed (a) by slow diagenesis of dust particles deposited on rock surfaces, (b) by leaching from the underlying rock substrate, or (c) by direct deposition of dissolved constituents in the atmosphere. Varnishes collected from smooth rock surfaces in the Mojave Desert and Death Valley, California are shown here to have highly enriched and fractionated trace-element abundances relative to upper continental crust (UCC). They are highly enriched in Co, Ni, Pb and the rare-earth elements (REEs). In particular, they have anomalously high Ce/La and low Y/Ho ratios. These features can only be explained by preferential scavenging of Co, Ni, Pb and the REEs by Fe-Mn oxyhydroxides in an aqueous environment. High field strength elements (HFSEs: Zr, Hf, Ta, Nb, Th), however, show only small enrichments despite the fact that these elements should also be strongly scavenged by Fe-Mn oxyhydroxides. This suggests that their lack of enrichment is a feature inherited from a solution initially poor in HFSEs. The first two scenarios for varnish formation can be ruled out as follows. The high enrichment factors of Fe, Mn and many trace elements cannot be generated by mass loss associated with post-depositional diagenesis of dust particles because such a process predicts only a small increase in concentration. In addition, the highly fractionated abundance patterns of particle reactive element pairs (e.g., Ce/La and Y/Ho) rules out leaching of the rock substrate. This is because if leaching were to occur, varnishes would grow from the inside to the outside, and thus any particle-reactive trace element leached from the substrate would be quantitatively sequestered in the Fe-Mn oxyhydroxide layers, prohibiting any significant elemental fractionations. One remaining possibility is that the Fe, Mn and trace metals in varnish are

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

    Science.gov (United States)

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

    2018-07-01

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

  6. The effects of atmospheric nitrogen deposition on terrestrial and freshwater biodiversity

    Science.gov (United States)

    Baron, Jill S.; Barber, Mary C.; Adams, Mark; Agboola, Julius I.; Allen, Edith B.; Bealey, William J.; Bobbink, Roland; Bobrovsky, Maxim V.; Bowman, William D.; Branquinho, Cristina; Bustamente, Mercedes M. C.; Clark, Christopher M.; Cocking, Edward C.; Cruz, Cristina; Davidson, Eric A.; Denmead, O. Tom; Dias, Teresa; Dise, Nancy B.; Feest, Alan; Galloway, James N.; Geiser, Linda H.; Gilliam, Frank S.; Harrison, Ian J.; Khanina, Larisa G.; Lu, Xiankai; Manrique, Esteban; Ochoa-Hueso, Raul; Ometto, Jean P. H. B.; Payne, Richard; Scheuschner, Thomas; Sheppard, Lucy J.; Simpson, Gavin L.; Singh, Y. V.; Stevens, Carly J.; Strachan, Ian; Sverdrup, Harald; Tokuchi, Naoko; van Dobben, Hans; Woodin, Sarah

    2014-01-01

    This chapter reports the findings of a Working Group on how atmospheric nitrogen (N) deposition affects both terrestrial and freshwater biodiversity. Regional and global scale impacts on biodiversity are addressed, together with potential indicators. Key conclusions are that: the rates of loss in biodiversity are greatest at the lowest and initial stages of N deposition increase; changes in species compositions are related to the relative amounts of N, carbon (C) and phosphorus (P) in the plant soil system; enhanced N inputs have implications for C cycling; N deposition is known to be having adverse effects on European and North American vegetation composition; very little is known about tropical ecosystem responses, while tropical ecosystems are major biodiversity hotspots and are increasingly recipients of very high N deposition rates; N deposition alters forest fungi and mycorrhyzal relations with plants; the rapid response of forest fungi and arthropods makes them good indicators of change; predictive tools (models) that address ecosystem scale processes are necessary to address complex drivers and responses, including the integration of N deposition, climate change and land use effects; criteria can be identified for projecting sensitivity of terrestrial and aquatic ecosystems to N deposition. Future research and policy-relevant recommendations are identified.

  7. Use of mosses as biomonitors of atmospheric deposition of trace elements

    International Nuclear Information System (INIS)

    Steinnes, E.

    2000-01-01

    Some basic facts about the use of mosses as biomonitors of atmospheric trace element deposition are reviewed, and advantages and limitations of this approach are discussed, largely on the basis of experience from regular use of this technique in Norway over the last 20 years. Topics discussed include different versions of the moss technique, mechanisms and efficiencies of trace element uptake, conversion of concentrations in moss to bulk deposition rates, and contribution from sources other than air pollution to the elemental composition of different elements. Suggestions are presented for further work in order to extend the use of mosses as biomonitors. (author)

  8. Distribution of atmospheric mercury in northern Southeast Asia and South China Sea during Dongsha Experiment

    Science.gov (United States)

    Sheu, Guey-Rong; Lin, Neng-Huei; Lee, Chung-Te; Wang, Jia-Lin; Chuang, Ming-Tung; Wang, Sheng-Hsiang; Chi, Kai Hsine; Ou-Yang, Chang-Feng

    2013-10-01

    Northern South China Sea (SCS) is adjacent to major atmospheric mercury (Hg) emission source regions; however, studies concerning regional atmospheric Hg distribution and cycling are very limited. Accordingly, measurements of atmospheric Hg were conducted in March and April during the 2010 Dongsha Experiment to study its spatial and temporal distribution. Atmospheric Hg was measured at Hengchun and Dongsha Island (Taiwan), Da Nang (Vietnam), Chiang Mai (Thailand) and over the northern SCS. Atmospheric Hg concentrations ranged between 1.54 and 6.83 ng m-3, mostly higher than the Northern Hemisphere background value. Regional wind fields and backward trajectories indicated that the atmospheric Hg concentrations over northern SCS should principally reflect the export of the East Asian Hg emissions by northeast monsoon. However, significantly elevated Hg concentrations were always observed at Da Nang, possibly due to the influence of local Hg emissions. Chiang Mai is located in the intense biomass burning region in northern Thailand. Therefore, atmospheric Hg concentrations at Chiang Mai reflected the influence of regional biomass burning Hg emissions. Two dust storms were encountered at Dongsha Island, one on March 16 and the other on March 21, with atmospheric Hg enhancements. Compared with the 2008 summer values, elevated Hg levels were observed at Dongsha Island in the spring of 2010. Summer air masses were mainly from the deep SCS, representing relatively clean marine air. On the other hand, air masses were from the north in spring, passing eastern China or Taiwan prior to reaching Dongsha Island. Results of this research thus demonstrated the transport of atmospheric Hg from the East Asian continent to northern SCS by regional monsoon activity in spring, but special events, such as biomass burning and dust storms, can also cause enhancements of ambient Hg levels.

  9. NKS NordRisk. Atlas of long-range atmospheric dispersion and deposition of radionuclides from selected risk sites in the Northern Hemisphere

    International Nuclear Information System (INIS)

    Havskov Soerensen, J.; Baklanov, A.; Mahura, A.; Lauritzen, Bent; Mikkelsen, Torben

    2008-07-01

    Within the NKS NordRisk project, 'Nuclear risk from atmospheric dispersion in Northern Europe', the NKS NordRisk Atlas has been developed. The atlas describes risks from hypothetical long-range atmospheric dispersion and deposition of radionuclides from selected nuclear risk sites in the Northern Hemisphere. A number of case studies of long-term long-range atmospheric transport and deposition of radionuclides has been developed, based on two years of meteorological data. Radionuclide concentrations in air and radionuclide depositions have been evaluated and examples of long-term averages of the dispersion and deposition and of the variability around these mean values are provided. (au)

  10. Chromium speciation in rainwater: temporal variability and atmospheric deposition

    Energy Technology Data Exchange (ETDEWEB)

    Kieber, R.J.; Willey, J.D.; Zvalaren, S.D. [University of North Carolina at Wilmington, Wilmington, NC (United States). Dept. of Chemistry

    2002-12-15

    Chromium is released into the atmosphere by a variety of anthropogenic activities which include steel manufacturing, leather tanning, wood presentation and fossil fuel combustion. The concentrations of the various chromium species were determined in 89 rainwater samples collected in Wilmington, NC from October 1, 1999 to December 31, 2001. Volume weighted annual average concentrations of Cr{sub total}, particulate Cr, Cr(III)(aq), and Cr(VI)(aq) were 4.6, 2.2, 0.8 and 1.2 nM, respectively. There was distinct seasonal and diurnal variability in the concentrations of the various chromium species. Chromium emissions to the global atmosphere by both natural and anthropogenic sources are estimated to be 2.2 x 10{sup 9} mol/yr. Using rainwater concentration data along with other published rainwater Cr concentrations and an estimate for total global annual rain, the total global flux of chromium removed from the atmosphere via wet deposition is 2.1 x 10{sup 9} mol/yr. This represents complete removal of Cr and indicates that essentially all chromium released into the global atmosphere is removed via rain. About half this chromium is dissolved with roughly equal concentrations of toxic Cr(VI) and relatively harmless Cr(III) species. 48 refs., 4 figs., 3 tabs.

  11. Impacts of atmospheric nitrogen deposition on vegetation and soils in Joshua Tree National Park

    Science.gov (United States)

    E.B. Allen; L. Rao; R.J. Steers; A. Bytnerowicz; M.E. Fenn

    2009-01-01

    The western Mojave Desert is downwind of nitrogen emissions from coastal and inland urban sources, especially automobiles. The objectives of this research were to measure reactive nitrogen (N) in the atmosphere and soils along a N-deposition gradient at Joshua Tree National Park and to examine its effects on invasive and native plant species. Atmospheric nitric acid (...

  12. Indirect N2O emission due to atmospheric N deposition for the Netherlands

    International Nuclear Information System (INIS)

    Denier van der Gon, H.; Bleeker, A.

    2005-10-01

    Nitrous oxide (N2O) is a potent greenhouse gas produced in soils and aquatic systems. The UNFCCC requires participants to report 'indirect' N2O emissions, following from agricultural N losses to ground- and surface water and N deposition on (other) ecosystems due to agricultural sources. Indirect N2O emission due to atmospheric N deposition is presently not reported by the Netherlands. In this paper, we quantify the consequences of various tiers to estimate indirect N2O due to deposition for a country with a high agricultural N use and discuss the reliability and potential errors in the IPCC methodology. A literature review suggests that the current IPCC default emission factor for indirect N2O from N deposition is underestimated by a factor 2. Moreover, considering anthropogenic N emissions from agriculture only and not from e.g., traffic and industry, results in further underestimation of indirect N2O emissions. We calculated indirect N2O emissions due to Dutch anthropogenic N emissions to air by using official Dutch N emission data as input in an atmospheric transport and deposition model in combination with land use databases. Next, land use-specific emission factors were used to estimate the indirect N2O emission. This revealed that (1) for some countries, like the Netherlands, most agricultural N emitted will be deposited on agricultural soils, not on natural ecosystems and, (2) indirect N2O emissions are at least 20% higher because more specific emission factors can be applied that are higher than the IPCC default. The results suggest that indirect N2O emission due to deposition is underestimated in current N2O budgets

  13. Modelling the impact of climate change and atmospheric N deposition on French forests biodiversity

    International Nuclear Information System (INIS)

    Rizzetto, Simon; Belyazid, Salim; Gégout, Jean-Claude; Nicolas, Manuel; Alard, Didier; Corcket, Emmanuel; Gaudio, Noémie; Sverdrup, Harald; Probst, Anne

    2016-01-01

    A dynamic coupled biogeochemical–ecological model was used to simulate the effects of nitrogen deposition and climate change on plant communities at three forest sites in France. The three sites had different forest covers (sessile oak, Norway spruce and silver fir), three nitrogen loads ranging from relatively low to high, different climatic regions and different soil types. Both the availability of vegetation time series and the environmental niches of the understory species allowed to evaluate the model for predicting the composition of the three plant communities. The calibration of the environmental niches was successful, with a model performance consistently reasonably high throughout the three sites. The model simulations of two climatic and two deposition scenarios showed that climate change may entirely compromise the eventual recovery from eutrophication of the simulated plant communities in response to the reductions in nitrogen deposition. The interplay between climate and deposition was strongly governed by site characteristics and histories in the long term, while forest management remained the main driver of change in the short term. - Highlights: • The effects of N atmospheric deposition and climate change on vegetation were simulated. • The model ForSAFE-Veg was calibrated and validated carefully for three forests in France. • Climate has a greater influence on vegetation than N deposition in conifer forests. • N-poor ecosystems are, however, more sensitive to N deposition than to climate change. - Compared to nitrogen atmospheric deposition, climate appears to be the main driver of change in forest plant biodiversity on a century scale, except in N-poor ecosystems.

  14. Oxidation of elemental mercury in the atmosphere; Constraints imposed by global scale modelling

    Energy Technology Data Exchange (ETDEWEB)

    Bergan, Torbjoern; Rodhe, Henning [Stockholm Univ. (Sweden). Dept. of Meteorology

    2000-05-01

    Based on the global mercury model published by Bergan et al. (1999), we present here further results from simulations where the central theme has been to evaluate the role of ozone and the hydroxyl radical as possible gas phase oxidants for the oxidation of elemental mercury in the atmosphere. The magnitude of natural and man-made mercury emissions are taken from recent literature estimates and the flux from land areas is assumed to vary by season. We consider only two mercury reservoirs, elemental mercury, Hg{sup 0}, and the more soluble divalent form, Hgll. Wet and dry deposition of Hgll is explicitly treated. Applying monthly mean fields of ozone for the oxidation of gas phase Hg{sup 0} and using the reaction rate by Hall (1995) yields a global transformation of Hg{sup 0} to Hgll which is too slow to keep the simulated concentration of Hg{sup 0} near observed values. This shows that there are additional important removal processes for Hg{sup 0} or that the reaction rate proposed by Hall (1995) is too slow. A simulation in which the oxidation rate was artificially increased, so that the global turn-over time of Hg{sup 0} was one year and the simulated average concentration of Hg{sup 0} was realistic, produced latitudinal and seasonal variations in Hg{sup 0} that did not support the hypothesis that gas phase reaction with O{sub 3} is the major oxidation process for Hg{sup 0}. Recent studies indicate that OH may be an important gas phase oxidant for Hg{sup 0}. Using OH as the oxidant and applying the preliminary oxidation rate by Sommar et al. (1999) gave an unrealistically large removal of Hg{sup 0} from the atmosphere. From calculations using a slower reaction rate, corresponding to a turn-over time of Hg{sup 0} of one year, we calculated concentrations of both Hg{sup 0} in surface air and Hgll in precipitation which correspond, both in magnitude and temporal variation, to seasonal observations in Europe and North America. This result supports the suggestion that

  15. [Heavy metals contents and Hg adsorption characteristics of mosses in virgin forest of Gongga Mountain].

    Science.gov (United States)

    Liang, Peng; Yang, Yong-Kui; He, Lei; Wang, Ding-Yong

    2008-06-01

    Seven main moss species in the Hailuogou virgin forest of Gongga Mountain were sampled to determine their heavy metals (Hg, Cr, Cd, Ni, Pb, Cu, Mn, Zn and Fe) content, and two widely distributed species, Pleurozium schreberi (Brid.) Mitt. and Racomitrium laetum Besch., were selected to study their Hg adsorption characteristics. The results showed that the heavy metals contents in the mosses were lower than the background values in Europe and America, except that the Cd had a comparable value, which indicated that the atmosphere in study area was not polluted by heavy metals and good in quality. The Hg adsorption by P. schreberi and R. laetum was an initiative and rapid process, with the equilibrium reached in about two hours, and could be well fitted by Freundlich and Langmuir equations. Based on Langmuir equation, the maximum Hg adsorption capacities of P. schreberi and R. laetum were 15.24 and 8.19 mg x g(-1), respectively, suggesting that the two mosses had a good capacity of Hg adsorption, and could be used as the bio-monitors of atmospheric Hg pollution.

  16. Forest vegetation as a sink for atmospheric particulates: Quantitative studies in rain and dry deposition

    International Nuclear Information System (INIS)

    Russel, I.J.; Choquette, C.E.; Fang, S.; Dundulis, W.P.; Pao, A.A.; Pszenny, A.A.P.

    1981-01-01

    Radionuclides in the atmosphere are associated with nonradioactive air particulates and hence serve to trace the fluxes of air particulates to various surfaces. Natural and artificial radioactivities found in the atmosphere have been measured in vegetation for 10 years to elucidate some of the mechanisms of acquirement by forest trees of atmospheric particulates. Whole tree analysis, in conjunction with soil assay, have served to establish the fraction of the flux of radionuclides retained by above-ground tissues of a forest stand. Interpretation is facilitated because most radionuclides in the atmosphere are superficially acquired. Typically 5--20% of the total open field flux is retained by the forest canopy in a moderately rainy climate (120 cm/year). Short-lived daughters of radon give a dry deposition velocity of particulates in the Aitken size range of 0.03--0.05 cm/s, thus permitting an estimate of transient removal by forest canopies by dry deposition of this size fraction

  17. Stability studies of Hg implanted YBa$_{2}$Cu$_{3}$O$_{6+x}$

    CERN Document Server

    Araújo, J P; Wahl, U; Marques, J G; Alves, E; Amaral, V S; Lourenço, A A; Galindo, V; Von Papen, T; Senateur, J P; Weiss, F; Vantomme, A; Langouche, G; Melo, A A; Da Silva, M F A; Soares, J C; Sousa, J B

    1999-01-01

    High quality YBa$_{2}$Cu$_{3}$O$_{6+x}$ (YBCO) superconducting thin films were implanted with the radioactive $^{197m}$Hg (T$_{1/2}$ = 24 h) isotope to low fluences of 10$^{13}$ atoms/cm$^{2}$ and 60 keV energy. The lattice location and stability of the implanted Hg were studied combining the Perturbed Angular Correlation (PAC) and Emission Channeling (EC) techniques. We show that Hg can be introduced into the YBCO lattice by ion implantation into unique regular sites. The EC data show that Hg is located on a highly symmetric site on the YBCO lattice, while the PAC data suggests that Hg occupies the Cu(1) site. Annealing studies were performed under vacuum and O$_{2}$ atmosphere and show that Hg starts to diffuse only above 653 K.

  18. Forest canopy uptake of atmospheric nitrogen deposition at eastern U.S. conifer sites: Carbon storage implications?

    Science.gov (United States)

    Herman Sievering; Ivan Fernandez; John Lee; John Hom; Lindsey Rustad

    2000-01-01

    Dry deposition determinations, along with wet deposition and throughfall (TF) measurements, at a spruce fir forest in central Maine were used to estimate the effect of atmospherically deposited nitrogen (N) uptake on forest carbon storage. Using nitric acid and particulate N as well as TF ammonium and nitrate data, the growing season (May-October) net canopy uptake of...

  19. Order-of-magnitude increase of Hg in Norwegian peat profiles since the outset of industrial activity in Europe

    International Nuclear Information System (INIS)

    Steinnes, Eiliv; Sjobakk, Torill Eidhammer

    2005-01-01

    Peat cores from six ombrotrophic bogs at different latitudes in Norway (58 deg N-69 deg N) were analysed for Hg by atomic fluorescence spectrometry. In all cases a smooth decrease of Hg with depth was observed down to 15-20 cm. At greater depths Hg showed a relatively constant level of the order of 10% of that in the peat surface layer. In the surface peat Hg concentrations exhibit moderate variation with latitude. The pre-industrial levels of Hg in the peat correspond to a net annual Hg accumulation of 0.3-0.9 μg m -2 . The Hg accumulation over the last 100 years is about 15 times higher on average than the pre-industrial level. The present work supports the view that a major part of the present atmospheric Hg in the Northern Hemisphere is of anthropogenic origin. It is speculated that the comparatively high Hg contemporary accumulation rates observed at the Andoya bog on 69 deg N may be related to the Arctic springtime depletion of Hg. - Results from analyses of ombrotrophic peat cores support the view that the present level of Hg 0 in the atmosphere is mainly of anthropogenic origin

  20. UFOMOD - atmospheric dispersion and deposition

    International Nuclear Information System (INIS)

    Panitz, H.J.; Matzerath, C.; Paesler-Sauer, J.

    1989-10-01

    The report gives an introduction into the modelling of atmospheric dispersion and deposition which has been implemented in the new program system UFOMOD for assessing the consequences after nuclear accidents. According to the new structure of UFOMOD, different trajectory models with ranges of validity near to the site and at far distances are applied. Emphasis is laid on the description of the segmented plume model MUSEMET and its affilated submodels, being the removal of activity from the cloud by dry and wet deposition, and special effects like plume rise and the behaviour of plumes released into building wakes. In addition, the evaluation of γ-dose correction factors to take account of the finite extent of the radioactive plume in the near range (up to about 20 km) are described. Only brief introductions are given into the principles of the other models available: the puff model RIMPUFF, the long-range puff model MESOS, and the special straight-line Gaussian model ISOLA which are used if low-level long-duration releases are considered. To define starting times of weather sequences and the probabilities of occurrence of these sequences, it is convenient to perform stratified sampling. Therefore, the preprocessing program package METSAM has been developed to perform for generic ACAs a random sampling of weather sequences out off a population of classified weather conditions. The sampling procedure and a detailed input/output (I/O) description is presented and an additional appendix, respectively. A general overview on the I/O structure of MUSEMET as well as a brief user guide to run the KfK version of the MESOS code are also given in the appendix. (orig.) [de

  1. Stability and diffusion of Hg implanted YBa2Cu3O6+x

    International Nuclear Information System (INIS)

    Araujo, J.P.; Correia, J.G.; Wahl, U.; Marques, J.G.; Alves, E.; Amaral, V.S.; Lourenco, A.A.; Galindo, V.; Papen, T. von; Senateur, J.P.; Weiss, F.; Vantomme, A.; Langouche, G.; Melo, A.A.; Silva, M.F. da; Soares, J.C.; Sousa, J.B.

    1999-01-01

    The radioactive isotope 197m Hg was implanted at 60 keV with low fluences (10 13 ions/cm 2 ) into YBa 2 Cu 3 O 6+x (YBCO) superconducting thin films at ISOLDE/CERN. We report on the Hg dynamics and stability inside the YBCO lattice as a function of annealing temperature up to 890 K in a vacuum or O 2 atmosphere. The perturbed angular correlation (PAC) technique was used for probing the Hg behavior at the atomic scale, while by monitoring the sample's activity in situ the Hg outdiffusion was studied. We found that Hg ions occupy unique lattice sites and that Hg should be bound to two apical oxygens. Hg diffusion occurs only for annealing temperatures above 653 K, in vacuum. The Hg migration energy was estimated to be E M =1.58±0.15 eV

  2. Atmospheric mercury accumulation between 5900 and 800 calibrated years BP in the high arctic of Canada recorded by Peat Hummocks

    DEFF Research Database (Denmark)

    Givelet, N.; Roos-Barraclough, F.; Goodsite, Michael Evan

    2004-01-01

    In this paper, we present the first comprehensive long-term record of preanthropogenic rates of atmospheric mercury accumulation in dated peat deposits for the High Arctic of Canada. Geochemical studies of two peat hummocks from Bathurst Island, Nunavut reveal substantial inputs from soil dust...... (titanium), marine aerosols (bromine), and mineral-water interactions (uranium). Mercury, however, was supplied to these peat mounds exclusively by atmospheric deposition. Mercury concentration measurements and age dating of the peat profiles indicate rather constant natural "background" mercury flux of ca....... 1 microgram per square meter per year from 5900 to 800 calibrated years BP. These values are well within the range of the mercury fluxes reported from other Arctic locations, but also by peat cores from southern Canada that provide a record of atmospheric Hg accumulation extending back 8000 years...

  3. Impact of acid atmosphere deposition on soils : field monitoring and aluminum chemistry

    NARCIS (Netherlands)

    Mulder, J.

    1988-01-01

    The effect of acid atmospheric deposition on concentrations and transfer of major solutes in acid, sandy soils was studied. Emphasis was given to mobilization and transport of potentially toxic aluminum. Data on solute concentrations and fluxes in meteoric water as well as soil solutions

  4. Assessment of atmospheric deposition of heavy metals and other elements in Belgrade using the moss biomonitoring technique and neutron activation analysis.

    Science.gov (United States)

    Anicić, Mira; Frontasyeva, Marina V; Tomasević, Milica; Popović, Aleksandar

    2007-06-01

    This study aimed at assessing atmospheric deposition of heavy metals and other elements using the moss genera Brachythecium sp. (B. rutabulum and B. salebrosum) and Eurhynchium sp. (E. hians and E. striatum) collected in autumn 2004 in the urban area of Belgrade. The concentrations of 36 elements (Na, Mg, Al, Cl, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, As, Se, Br, Rb, Sr, Mo, Sb, I, Cs, Ba, La, Ce, Sm, Tb, Dy, Hf, Ta, W, Hg, Th, U) were determined in moss and local topsoil samples by instrumental neutron activation analysis. The concentration of elements in moss positively correlated to those obtained for topsoil. High enrichment factors for As, Zn, Mo, Br, Sb, Se, Hg and Cl, calculated to continental crust composition, gave an evidence for anthropogenic impact on urban area, mainly due to intensive vehicular traffic and fossil fuel combustion. The concentration of elements in moss, characteristic for fossil fuel combustion, obtained in this study were substantially lower than in the previous investigation (2000) conducted in the area of Belgrade. The level of concentrations for V, Cr, Ni, and As in moss from this study correlated to those measured for neighboring countries, and were several times higher than the base-level data from low polluted areas. The level of accumulated elements in both investigated moss genera were similar and all studied species could be combined for biomonitoring purposes in urban areas.

  5. Assessment of atmospheric deposition of heavy metals and other elements in Belgrade using the moss biomonitoring technique and neutron activation analysis

    International Nuclear Information System (INIS)

    Anicic, M.; Tomasevic, M.; Frontas'eva, M.V.; Popovic, A.

    2006-01-01

    The study aimed at assessing atmospheric deposition of heavy metals and other elements using the moss genera Brachythecium sp. (B. rutabulum and B. salebrosum) and Eurhynchium sp. (E. hians and E. striatum) collected in autumn 2004 in the urban area of Belgrade. The concentrations of 36 elements (Na, Mg, Al, Cl, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, As, Se, Br, Rb, Sr, Mo, Sb, I, Cs, Ba, La, Ce, Sm, Tb, Dy, Hf, Ta, W, Hg, Th, U) were determined in moss and local topsoil samples by instrumental neutron activation analysis. The concentration of elements in moss positively correlated to those obtained for topsoil. High enrichment factors for As, Zn, Mo, Br, Sb, Se, Hg, and Cl, calculated to continental crust composition, gave an evidence for anthropogenic impact on urban area, mainly due to intensive vehicular traffic and fossil fuel combustion. The concentrations of elements in moss, characteristic for fossil fuel combustion, obtained in this study, were substantially lower than in the previous investigation (2000) conducted in the area of Belgrade. The level of concentrations for V, Cr, Ni, and As in moss from this study correlated to those measured for neighboring countries, and were several times higher than the base-level data from low polluted areas. The level of accumulated elements in both investigated moss genera were similar and all studied species could be combined for biomonitoring purposes in urban areas

  6. Hydrogenated amorphous silicon photoresists for HgCdTe patterning

    Energy Technology Data Exchange (ETDEWEB)

    Hollingsworth, R.E.; DeHart, C.; Wang, L.; Dinan, J.H.; Johnson, J.N.

    1997-07-01

    A process to use a hydrogenated amorphous silicon (a-Si:H) film as a dry photoresist mask for plasma etching of HgCdTe has been demonstrated. The a-Si:H films were deposited using standard plasma enhanced chemical vapor deposition with pure silane as the source gas. X-ray photoelectron spectra show that virtually no oxide grows on the surface of an a-Si:H film after 3 hours in air, indicating that it is hydrogen passivated. Ultraviolet light frees hydrogen from the surface and enhances the oxide growth rate. A pattern of 60 micron square pixels was transferred from a contact mask to the surface of an a-Si:H film by ultraviolet enhanced oxidation in air. For the conditions used, the oxide thickness was 0.5--1.0 nm. Hydrogen plasmas were used to develop this pattern by removing the unexposed regions of the film. A hydrogen plasma etch selectivity between oxide and a-Si:H of greater than 500:1 allows patterns as thick as 700 nm to be generated with this very thin oxide. These patterns were transferred into HgCdTe by etching in an electron cyclotron resonance plasma. An etch selectivity between a-Si:H and HgCdTe of greater than 4:1 was observed after etching 2,500 nm into the HgCdTe. All of the steps are compatible with processing in vacuum.

  7. Atmospheric deposition of inorganic nitrogen in Spanish forests of Quercus ilex measured with ion-exchange resins and conventional collectors

    Science.gov (United States)

    Héctor García-Gomez; Sheila Izquieta-Rojano; Laura Aguillaume; Ignacio González-Fernández; Fernando Valiño; David Elustondo; Jesús M. Santamaría; Anna Àvila; Mark E. Fenn; Rocío Alonso

    2016-01-01

    Atmospheric nitrogen deposition is one of the main threats for biodiversity and ecosystem functioning. Measurement techniques like ion-exchange resin collectors (IECs), which are less expensive and time-consuming than conventional methods, are gaining relevance in the study of atmospheric deposition and are recommended to expand monitoring networks. In the present work...

  8. Oxygen in the Martian atmosphere: Regulation of PO2 by the deposition of iron formations on Mars

    Science.gov (United States)

    Burns, Roger G.

    1992-01-01

    During Earth's early history, and prior to the evolution of its present day oxygenated atmosphere, extensive iron rich siliceous sedimentary rocks were deposited, consisting of alternating layers of silica (chert) and iron oxide minerals (hematite and magnetite). The banding in iron formations recorded changes of atmosphere-hydrosphere interactions near sea level in the ancient ocean, which induced the oxidation of dissolved ferrous iron, precipitation of insoluble ferric oxides and silica, and regulation of oxygen in Earth's early atmosphere. Similarities between the Archean Earth and the composition of the present day atmosphere on Mars, together with the pervasive presence of ferric oxides in the Martian regolith suggest that iron formation might also have been deposited on Mars and influenced the oxygen content of the Martian atmosphere. Such a possibility is discussed here with a view to assessing whether the oxygen content of the Martian atmosphere has been regulated by the chemical precipitation of iron formations on Mars.

  9. NKS NordRisk. Atlas of long-range atmospheric dispersion and deposition of radionuclides from selected risk sites in the Northern Hemisphere

    Energy Technology Data Exchange (ETDEWEB)

    Havskov Soerensen, J.; Baklanov, A.; Mahura, A. (Danish Meteorological Institute, Copenhagen (Denmark)); Lauritzen, Bent; Mikkelsen, Torben (Technical Univ. of Denmark, Risoe National Lab. for Sustainable Energy, Roskilde (Denmark))

    2008-07-15

    Within the NKS NordRisk project, 'Nuclear risk from atmospheric dispersion in Northern Europe', the NKS NordRisk Atlas has been developed. The atlas describes risks from hypothetical long-range atmospheric dispersion and deposition of radionuclides from selected nuclear risk sites in the Northern Hemisphere. A number of case studies of long-term long-range atmospheric transport and deposition of radionuclides has been developed, based on two years of meteorological data. Radionuclide concentrations in air and radionuclide depositions have been evaluated and examples of long-term averages of the dispersion and deposition and of the variability around these mean values are provided. (au)

  10. High 210Po atmospheric deposition flux in the subtropical coastal area of Japan

    International Nuclear Information System (INIS)

    Tateda, Yutaka; Iwao, Kenji

    2008-01-01

    Bulk atmospheric deposition fluxes of 210 Po and 210 Pb were measured at three coastal regions of Japan, the Pacific Ocean coastal area of the Japanese mainland (Odawa Bay), the Chinese continental side of Japanese coastal area (Tsuyazaki), and an isolated island near Okinawa (Akajima). Wet and dry fallout collectors were continuously deployed from September 1997 through August 1998 for periods of 3 to 31 days depending on the frequency of precipitation events. Annual 210 Pb deposition fluxes at Odawa Bay (35 o N 139 o E), Tsuyazaki (33 o N 130 o E) and Akajima (26 o N 127 o E) were 73.3 ± 8.0, 197 ± 35 and 78.5 ± 8.0 Bq m -2 y -1 , respectively. Higher 210 Pb deposition was observed at the Chinese continental side of Japanese coast than at the Pacific Ocean coastal site. The high 210 Pb atmospheric flux at the Chinese continental side coast was thought to be attributable to 222 Rn-rich air-mass transport from the Chinese continent during the winter monsoon. In contrast, the annual 210 Po deposition fluxes at the three study sites were 13.0 ± 2.3 (Odawa Bay), 21.9 ± 4.4 (Tsuyazaki) and 58.4 ± 7.7 (Akajima) Bq m -2 y -1 , respectively, indicating unusual high 210 Po deposition at Akajima during winter. Anomalous unsupported 210 Po input was observed during summer 1997, suggesting unknown source of 210 Po at this area

  11. Historical deposition and fluxes of mercury in Narraguinnep Reservoir, southwestern Colorado, USA

    International Nuclear Information System (INIS)

    Gray, John E.; Fey, David L.; Holmes, Charles W.; Lasorsa, Brenda K.

    2005-01-01

    Narraguinnep Reservoir has been identified as containing fish with elevated Hg concentrations and has been posted with an advisory recommending against consumption of fish. There are presently no point sources of significant Hg contamination to this reservoir or its supply waters. To evaluate potential historical Hg sources and deposition of Hg to Narraguinnep Reservoir, the authors measured Hg concentrations in sediment cores collected from this reservoir. The cores were dated by the 137 Cs method and these dates were further refined by relating water supply basin hydrological records with core sedimentology. Rates of historical Hg flux were calculated (ng/cm 2 /a) based on the Hg concentrations in the cores, sediment bulk densities, and sedimentation rates. The flux of Hg found in Narraguinnep Reservoir increased by approximately a factor of 2 after about 1970. The 3 most likely sources of Hg to Narraguinnep Reservoir are surrounding bedrocks, upstream inactive Au-Ag mines, and several coal-fired electric power plants in the Four Corners region. Patterns of Hg flux do not support dominant Hg derivation from surrounding bedrocks or upstream mining sources. There are 14 coal-fired power plants within 320 km of Narraguinnep Reservoir that produce over 80 x 10 6 MWH of power and about 1640 kg-Hg/a are released through stack emissions, contributing significant Hg to the surrounding environment. Two of the largest power plants, located within 80 km of the reservoir, emit about 950 kg-Hg/a. Spatial and temporal patterns of Hg fluxes for sediment cores collected from Narraguinnep Reservoir suggest that the most likely source of Hg to this reservoir is from atmospheric emissions from the coal-fired electric power plants, the largest of which began operation in this region in the late-1960s and early 1970s

  12. Does seasonal snowpacks enhance or decrease mercury contamination of high elevation ecosystems?

    Science.gov (United States)

    Pierce, A.; Fain, X.; Obrist, D.; Helmig, D.; Barth, C.; Jacques, H.; Chowanski, K.; Boyle, D.; William, M.

    2009-12-01

    Mercury (Hg) is an extremely toxic pollutant globally dispersed in the environment. Natural and anthropogenic sources emit Hg to the atmosphere, either as gaseous elemental mercury (GEM; Hg0) or as divalent mercury species. Due to the long lifetime of GEM mercury contamination is not limited to industrialized sites, but also a concern in remote areas such as high elevation mountain environments. During winter and spring 2009, we investigated the fate of atmospheric mercury deposited to mountain ecosystems in the Sierra Nevada (Sagehen station, California, USA) and the Rocky Mountains (Niwot Ridge station, Colorado, USA). At Sagehen, we monitored mercury in snow (surface snow sampling and snow pits), wet deposition, and stream water during the snow-dominated season. Comparison of Hg stream discharge to snow Hg wet deposition showed that only a small fraction of Hg wet deposition reached stream in the melt water. Furthermore, Hg concentration in soil transects (25 different locations) showed no correlations to wet deposition Hg loads due to pronounced altitudinal precipitation gradient suggesting that Hg deposited to the snowpack was not transferred to ecosystems. At Niwot Ridge, further characterization of the chemical transformation involving mercury species within snowpacks was achieved by 3-months of continuous monitoring of GEM and ozone concentrations in the snow air at eight depths from the soil-snow interface to the top of the up to 2 meter deep snowpack. Divalent mercury concentrations were monitored as well (surface snow sampling and snow pits). GEM levels in snow air exhibited strong diurnal pattern indicative of both oxidation and reduction processes. Low levels of divalent mercury concentrations in snow pack suggest that large fractions of Hg originally deposited as wet deposition was reemitted back to the atmosphere after reduction. Hence, these results suggest that the presence of a seasonal snowpack may decrease effective wet deposition of mercury and

  13. Thermally stimulated currents in α-HgI2 polycrystalline films

    International Nuclear Information System (INIS)

    Shiu, Y.-T.; Huang, T.-J.; Shih, C.-T.; Su, C.-F.; Lan, S.-M.; Chiu, K.-C.

    2007-01-01

    A study of thermally stimulated currents (TSC) is applied to α-HgI 2 polycrystalline films grown by physical vapour deposition with various thermal boundary conditions. Five TSC peaks are clearly observed and numerically fitted. The activation energy and the density of the trapping centre that corresponds to each TSC peak are then calculated. Finally, the effects of the deposition conditions on the TSC results are discussed

  14. A review of global environmental mercury processes in response to human and natural perturbations: Changes of emissions, climate, and land use.

    Science.gov (United States)

    Obrist, Daniel; Kirk, Jane L; Zhang, Lei; Sunderland, Elsie M; Jiskra, Martin; Selin, Noelle E

    2018-03-01

    We review recent progress in our understanding of the global cycling of mercury (Hg), including best estimates of Hg concentrations and pool sizes in major environmental compartments and exchange processes within and between these reservoirs. Recent advances include the availability of new global datasets covering areas of the world where environmental Hg data were previously lacking; integration of these data into global and regional models is continually improving estimates of global Hg cycling. New analytical techniques, such as Hg stable isotope characterization, provide novel constraints of sources and transformation processes. The major global Hg reservoirs that are, and continue to be, affected by anthropogenic activities include the atmosphere (4.4-5.3 Gt), terrestrial environments (particularly soils: 250-1000 Gg), and aquatic ecosystems (e.g., oceans: 270-450 Gg). Declines in anthropogenic Hg emissions between 1990 and 2010 have led to declines in atmospheric Hg 0 concentrations and Hg II wet deposition in Europe and the US (- 1.5 to - 2.2% per year). Smaller atmospheric Hg 0 declines (- 0.2% per year) have been reported in high northern latitudes, but not in the southern hemisphere, while increasing atmospheric Hg loads are still reported in East Asia. New observations and updated models now suggest high concentrations of oxidized Hg II in the tropical and subtropical free troposphere where deep convection can scavenge these Hg II reservoirs. As a result, up to 50% of total global wet Hg II deposition has been predicted to occur to tropical oceans. Ocean Hg 0 evasion is a large source of present-day atmospheric Hg (approximately 2900 Mg/year; range 1900-4200 Mg/year). Enhanced seawater Hg 0 levels suggest enhanced Hg 0 ocean evasion in the intertropical convergence zone, which may be linked to high Hg II deposition. Estimates of gaseous Hg 0 emissions to the atmosphere over land, long considered a critical Hg source, have been revised downward, and

  15. Atmospheric particle characterization, distribution, and deposition in Xi'an, Shaanxi Province, Central China

    Energy Technology Data Exchange (ETDEWEB)

    Cao Zongze; Yang Yuhua [Key Laboratory of Analytical Chemistry for Life Science of Shaanxi Province, School of Chemistry and Materials Science, Shaanxi Normal University, Xi' an, 710062 (China); Department of Chemistry and Biology, Ryerson University, 350 Victoria Street, Toronto, Ontario, M5B 2K3 (Canada); Lu, Julia, E-mail: julialu@ryerson.c [Department of Chemistry and Biology, Ryerson University, 350 Victoria Street, Toronto, Ontario, M5B 2K3 (Canada); Key Laboratory of Analytical Chemistry for Life Science of Shaanxi Province, School of Chemistry and Materials Science, Shaanxi Normal University, Xi' an, 710062 (China); Zhang Chengxiao, E-mail: cxzhang@snnu.edu.c [Key Laboratory of Analytical Chemistry for Life Science of Shaanxi Province, School of Chemistry and Materials Science, Shaanxi Normal University, Xi' an, 710062 (China)

    2011-02-15

    Physical characterization and chemical analysis of settled dusts collected in Xi'an from November 2007 to December 2008 show that (1) dust deposition rates ranged from 14.6 to 350.4 g m{sup -2} yr{sup -1}. The average deposition rate (76.7 g m{sup -2} yr{sup -1}) ranks the 11th out of 56 dust deposition rates observed throughout the world. The coal-burning power was the major particle source; (2) on average (except site 4), {approx}10% of the settled dusts having size <2.6, {approx}30% having size <10.5, and >70% having size <30 {mu}m; (3) the concentrations for 20 out of 27 elements analyzed were upto 18 times higher than their soil background values in China. With such high deposition rates of dusts that contain elevated levels of toxic elements, actions should be taken to reduce emission and studies are needed to assess the potential impacts of settled particles on surface ecosystem, water resource, and human health in the area. - Research highlights: High atmospheric dust deposition rate in Xi'an, Shaanxi, China. Coal-burning power plan being a major source of particulate matter in Xi'an area. High levels of toxic elements in the settled dusts. Enrichment of heavy metals (e.g., Pb, Ni, Cu) in fine particles. - Atmospheric dust deposition rate is high and the levels of toxic elements associated with the settled dusts are elevated in Xi'an, Shaanxi, China.

  16. Evaluation of the pollution and human health risks posed by heavy metals in the atmospheric dust in Ebinur Basin in Northwest China.

    Science.gov (United States)

    Abuduwailil, Jilili; Zhaoyong, Zhang; Fengqing, Jiang

    2015-09-01

    Recently, a large amount of research assessing pollution levels and the related health risks posed by atmosphere dust has been undertaken worldwide. However, little work has been done in the oases of the arid regions of Northwest China. In this paper, we studied the pollution and health risks over a year of seven heavy metals in the atmospheric dust of Ebinur Basin, a typical oasis in Northwest China. The results showed the following: (1) The annual amount of atmospheric deposition in Ebinur Basin was 298.23 g m(-2) and the average monthly atmospheric deposition was 25.06 g m(-2). The average and maximum values of the seven heavy metals measured were all below the National Soil Environmental Quality Standards (2nd). (2) Heavy metals of Cu, Cr, and As in the atmospheric deposition mainly originated from the natural geological background, while Zn came from human activity. This study also showed that among the seven measured heavy metals, the ratios of the no-pollution status of Pb, Cd, and Hg were higher than those of others with moderate degrees of pollution also accounting for a certain ratio. (3) The carcinogenic risks from As, Cd, and Cr were all lower than the corresponding standard limit values, and these metals are considered not harmful to the health of the basin. However, there is a relatively high risk of exposure for children from hand-to-mouth intake, which is worthy of attention. This research showed that both human activity and natural factors, such as wind and altitude, influenced the heavy metal contents in the atmospheric dust of the study area. Furthermore, recent human activity in the study area had the most negative influence on the accumulation of the heavy metals and the corresponding health risks, especially for Hg, Pb, and Cd, which is worthy of attention.

  17. Development of ion-exchange collectors for monitoring atmospheric deposition of inorganic pollutants in Alaska parklands

    Science.gov (United States)

    Brumbaugh, William G.; Arms, Jesse W.; Linder, Greg L.; Melton, Vanessa D.

    2016-09-19

    Between 2010 and 2014, the U.S. Geological Survey completed a series of laboratory and field experiments designed to develop methodology to support the National Park Service’s long-term atmospheric pollutant monitoring efforts in parklands of Arctic Alaska. The goals of this research were to develop passive sampling methods that could be used for long-term monitoring of inorganic pollutants in remote areas of arctic parklands and characterize relations between wet and dry deposition of atmospheric pollutants to that of concentrations accumulated by mosses, specifically the stair-step, splendid feather moss, Hylocomium splendens. Mosses and lichens have been used by National Park Service managers as atmospheric pollutant biomonitors since about 1990; however, additional research is needed to better characterize the dynamics of moss bioaccumulation for various classes of atmospheric pollutants. To meet these research goals, the U.S. Geological Survey investigated the use of passive ionexchange collectors (IECs) that were adapted from the design of Fenn and others (2004). Using a modified IEC configuration, mulitple experiments were completed that included the following: (a) preliminary laboratory and development testing of IECs, (b) pilot-scale validation field studies during 2012 with IECs at sites with instrumental monitoring stations, and (c) deployment of IECs in 2014 at sites in Alaska having known or suspected regional sources of atmospheric pollutants where samples of Hylocomium splendens moss also could be collected for comparison. The targeted substances primarily included ammonium, nitrate, and sulfate ions, and certain toxicologically important trace metals, including cadmium, cobalt, copper, nickel, lead, and zinc.Deposition of atmospheric pollutants is comparatively low throughout most of Alaska; consequently, modifications of the original IEC design were needed. The most notable modification was conversion from a single-stage mixed-bed column to a two

  18. The electrochemical properties of LaNi5 electrodes doped with multi-walled carbon nanotubes synthesized by chemical vapor deposition and treated at different temperatures in a nitrogen atmosphere

    International Nuclear Information System (INIS)

    Yi Shuangping; Zhang Haiyan; Zhang Guoqin; Hu Shoule; Pei Lei; Yin Jianfen

    2006-01-01

    The electrochemical properties of LaNi 5 electrodes doped with multi-walled carbon nanotubes (MWNTs) treated at different temperatures in a nitrogen atmosphere were investigated. The MWNTs were synthesized by chemical vapor deposition (CVD). The purified carbon nanotubes (CNTs) were annealed during 1.5 h in a nitrogen atmosphere at different temperatures. A three-electrode system was applied. The CNTs-LaNi 5 electrodes were prepared by mixing CNTs and LaNi 5 in a weight ratio of 1:10, and used as the working electrode; Ni(OH) 2 /NiOOH worked as the counter electrode and Hg/HgO as the reference electrode. A 6 mol/L KOH solution acted as the electrolyte. MWNTs annealed at different temperatures in a nitrogen atmosphere showed large differences in the electrochemical hydrogen storage capability under the same testing condition. The CNTs-LaNi 5 electrodes with 20-40 nm diameter CNTs heated at 800 deg. C in nitrogen proved to have the best electrochemical hydrogen storage capacity, with a discharging capacity of 519.1 mAh/g and a corresponding discharging plateau voltage of 1.18 V, at a 200 mA/g charge current density and a 60 Ma/g discharge current density with a 0.2 V discharge voltage limit. From 500 to 800 deg. C, the higher the annealing temperature,the better the electrochemical hydrogen storage property. However, CNTs-LaNi 5 electrodes with 20-40 nm diameter CNTs heated at 900 deg. C in nitrogen have a lower capacity of 476.2 mAh/g under the same testing condition. This shows that the annealing temperature of CNTs is an important factor that influences their electrochemical hydrogen storage performance

  19. Modeling the biogeochemical impact of atmospheric phosphate deposition from desert dust and combustion sources to the Mediterranean Sea

    Science.gov (United States)

    Richon, Camille; Dutay, Jean-Claude; Dulac, François; Wang, Rong; Balkanski, Yves

    2018-04-01

    Daily modeled fields of phosphate deposition to the Mediterranean from natural dust, anthropogenic combustion and wildfires were used to assess the effect of this external nutrient on marine biogeochemistry. The ocean model used is a high-resolution (1/12°) regional coupled dynamical-biogeochemical model of the Mediterranean Sea (NEMO-MED12/PISCES). The input fields of phosphorus are for 2005, which are the only available daily resolved deposition fields from the global atmospheric chemical transport model LMDz-INCA. Traditionally, dust has been suggested to be the main atmospheric source of phosphorus, but the LMDz-INCA model suggests that combustion is dominant over natural dust as an atmospheric source of phosphate (PO4, the bioavailable form of phosphorus in seawater) for the Mediterranean Sea. According to the atmospheric transport model, phosphate deposition from combustion (Pcomb) brings on average 40.5×10-6 mol PO4 m-2 yr-1 over the entire Mediterranean Sea for the year 2005 and is the primary source over the northern part (e.g., 101×10-6 mol PO4 m-2 yr-1 from combustion deposited in 2005 over the north Adriatic against 12.4×10-6 from dust). Lithogenic dust brings 17.2×10-6 mol PO4 m-2 yr-1 on average over the Mediterranean Sea in 2005 and is the primary source of atmospheric phosphate to the southern Mediterranean Basin in our simulations (e.g., 31.8×10-6 mol PO4 m-2 yr-1 from dust deposited in 2005 on average over the south Ionian basin against 12.4×10-6 from combustion). The evaluation of monthly averaged deposition flux variability of Pdust and Pcomb for the 1997-2012 period indicates that these conclusions may hold true for different years. We examine separately the two atmospheric phosphate sources and their respective flux variability and evaluate their impacts on marine surface biogeochemistry (phosphate concentration, chlorophyll a, primary production). The impacts of the different phosphate deposition sources on the biogeochemistry of the

  20. Accounting for the effect of temperature in clarifying the response of foliar nitrogen isotope ratios to atmospheric nitrogen deposition.

    Science.gov (United States)

    Chen, Chongjuan; Li, Jiazhu; Wang, Guoan; Shi, Minrui

    2017-12-31

    Atmospheric nitrogen deposition affects nitrogen isotope composition (δ 15 N) in plants. However, both negative effect and positive effect have been reported. The effects of climate on plant δ 15 N have not been corrected for in previous studies, this has impeded discovery of a true effect of atmospheric N deposition on plant δ 15 N. To obtain a more reliable result, it is necessary to correct for the effects of climatic factors. Here, we measured δ 15 N and N contents of plants and soils in Baiwangshan and Mount Dongling, north China. Atmospheric N deposition in Baiwangshan was much higher than Mount Dongling. Generally, however, foliar N contents showed no difference between the two regions and foliar δ 15 N was significantly lower in Baiwangshan than Mount Dongling. The corrected foliar δ 15 N after accounting for a predicted value assumed to vary with temperature was obviously more negative in Baiwangshan than Mount Dongling. Thus, this suggested the necessity of temperature correction in revealing the effect of N deposition on foliar δ 15 N. Temperature, soil N sources and mycorrhizal fungi could not explain the difference in foliar δ 15 N between the two regions, this indicated that atmospheric N deposition had a negative effect on plant δ 15 N. Additionally, this study also showed that the corrected foliar δ 15 N of bulk data set increased with altitude above 1300m in Mount Dongling, this provided an another evidence for the conclusion that atmospheric N deposition could cause 15 N-depletion in plants. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Deposition and surface characterization of nanoparticles of zinc oxide using dense plasma focus device in nitrogen atmosphere

    International Nuclear Information System (INIS)

    Malhotra, Yashi; Srivastava, M P; Roy, Savita

    2010-01-01

    Nanoparticles of zinc oxide from zinc oxide pellets in the nitrogen plasma atmosphere are deposited on n and p type silicon substrates using Dense Plasma Focus device. The hot and dense nitrogen plasma formed during the focus phase ionizes the ZnO pellet, which then move upward in a fountain like shape and gets deposited on substrates which are placed above the top of the anode. Structural and surface properties of the deposited ZnO are investigated using X-ray diffraction and Atomic force microscope (AFM). X-ray spectra shows the diffraction plane (002) of ZnO nanoparticles deposited on Si with few shots in nitrogen atmosphere. AFM investigations revealed that there are nanoparticles of size between 15-80 nm on n-Si and p-Si substrates. The deposition on n-type Si is better than the p-type Si can be seen from AFM images, this may be due to different orientation of silicon.

  2. Nitrogen concentrations in mosses indicate the spatial distribution of atmospheric nitrogen deposition in Europe

    International Nuclear Information System (INIS)

    Harmens, H.; Norris, D.A.; Cooper, D.M.; Mills, G.; Steinnes, E.; Kubin, E.; Thoeni, L.; Aboal, J.R.; Alber, R.; Carballeira, A.; Coskun, M.; De Temmerman, L.; Frolova, M.; Gonzalez-Miqueo, L.

    2011-01-01

    In 2005/6, nearly 3000 moss samples from (semi-)natural location across 16 European countries were collected for nitrogen analysis. The lowest total nitrogen concentrations in mosses ( 2 = 0.91) linear relationship was found between the total nitrogen concentration in mosses and measured site-specific bulk nitrogen deposition rates. The total nitrogen concentrations in mosses complement deposition measurements, helping to identify areas in Europe at risk from high nitrogen deposition at a high spatial resolution. - Highlights: → Nitrogen concentrations in mosses were determined at ca. 3000 sites across Europe. → Moss concentrations were compared with EMEP modelled nitrogen deposition. → The asymptotic relationship for Europe showed saturation at ca. 15 kg N ha -1 y -1 . → Linear relationships were found with measured nitrogen deposition in some countries. → Moss concentrations complement deposition measurements at high spatial resolution. - Mosses as biomonitors of atmospheric nitrogen deposition in Europe.

  3. Atmospheric Deposition Modeling Results

    Data.gov (United States)

    U.S. Environmental Protection Agency — This asset provides data on model results for dry and total deposition of sulfur, nitrogen and base cation species. Components include deposition velocities, dry...

  4. Atmospheric deposition of trace elements around Ulan Bator city studied by moss and lichen biomonitoring technique and INAA

    International Nuclear Information System (INIS)

    Ganbold, G.; Gehrbish, Sh.; Tsehndehehkhuu, Ts.; Gundorina, S.F.; Frontas'eva, M.V.; Ostrovnaya, T.M.; Pavlov, S.S.

    2005-01-01

    For the first time the moss and lichen biomonitoring technique has been applied to air pollution in Mongolia (Ulan-Bator, the capital city). INAA at the IBR-2 reactor has made it possible to determine the content of 35 elements in moss and lichen biomonitors. Samples collected at sites located 10-15 km from the center of Ulan-Bator were analyzed by Instrumental Neutron Activation Analysis (INAA) using epithermal neutrons. The mosses (Rhytidium rugosum, Thuidium abietinum, Entodon concinnus) and lichens (Cladonia stellaris, Parmelia separata) were used to study the atmospheric deposition of trace elements. It was shown that the suggested types of mosses could be used as suitable biomonitors to estimate the concentration levels of heavy metals and trace elements in Ulan-Bator atmospheric deposition. The results are compared to the data of atmospheric deposition of some European countries

  5. Atmospheric dispersion and deposition of 131I released from the Hanford Site

    International Nuclear Information System (INIS)

    Ramsdell, J.V. Jr.; Simonen, C.A.; Burk, K.W.; Stage, S.A.

    1996-01-01

    Approximately 2.6 x 10 4 TBq (700,000 Ci) of 131 I were released to the air from reactor fuel processing plants on the Hanford Site in southcentral Washington State from December 1944 through December 1949. The Hanford Environmental Dose Reconstruction Project developed a suite of codes to estimate the doses that might have resulted from these releases. The Regional Atmospheric Transport Code for Hanford Emission Tracking (RATCHET) computer code is part of this suite. The RATCHET code implements a Lagrangian-trajectory, Gaussian-puff dispersion model that uses hourly meterological and release rate data to estimate daily time-integrated air concentrations and surface contamination for use, in dose estimates. In this model, iodine is treated as a mixture of three species (inorganic gases, organic gases, and particles). Model deposition parameters are functions of the mixture and meterological conditions. A resistance model is used to calculate dry deposition velocities. Equilibrium between concentrations in the precipitation and the air near the ground is assumed in calculating wet deposition of gases, and irreversible washout of the particles is assumed. RATCHET explicitly treats the uncertainties in model parameters and meteorological conditions. Uncertainties in 131 I release rates and partitioning among the nominal species are treated by varying model input. The results of 100 model runs for December 1944 through December 1949 indicate that monthly average air concentrations and deposition have uncertainties ranging from a factor of two near the center of the time-integrated plume to more than an order of magnitude near the edge. These results indicate that ∼10% of the 131 I released to the atmosphere decayed during transit in the study area, ∼56% was deposited within the study area, and the remaining 34% was transported out of the study area while still in the air

  6. Deposition and retention of air pollutants on vegetation and other atmospheric interfaces

    International Nuclear Information System (INIS)

    Jonas, R.

    1984-09-01

    The question of the deposition of aerosols and gases are applied to biological and ecological problems concerning the filtering aspect of atmospheric interfaces, especially vegetation, with respect to air pollution, and also the resulting pollutant effect. In order to determine the deposition of aerosols, numerous field experiments were carried out. The deposition of gases was treated on the basis of current literature data. The experiments indicate that the deposition of aerosols on grass largely depends on aerosol diameter, dry weight per unit area and the wind velocity or turbulence of the air layer near the ground. Of the interfaces studied, namely soil without vegetation, water, filter paper, smooth and structured metals, grass, clover and trees, the latter had the greatest dust collecting capability. It is recommended that in the afforestation of areas in the close proximity of industrial regions the common beech, silver birch and Japanese larch should be taken into particular consideration due to their great deposition effectiveness with respect to dusts and their comparatively high resistance to pollutant gases. Silver birch and moreover red horse chestnut should be considered for filtering the air in urban regions because of the high aerosol deposition. (orig./HP) [de

  7. Mercury in the mix: An in situ mesocosm approach to assess relative contributions of mercury sources to methylmercury production and bioaccumulation in the Sacramento-San Joaquin Delta

    Science.gov (United States)

    Fleck, J.; Krabbenhoft, D. P.; Kraus, T. E. C.; Ackerman, J.; Stumpner, E. B.; DeWild, J.; Marvin-DiPasquale, M. C.; Tate, M.; Ogorek, J.

    2014-12-01

    Mercury (Hg) contamination is considered one of the greatest threats to the Sacramento-San Joaquin Delta and the San Francisco Estuary ecosystems. This threat is driven by the transformation of Hg, deposited in the Delta from erosion of upstream historic mining debris and atmospheric deposition, by native bacteria into the more toxic and biologically available form, methylmercury (MeHg), in the wetlands and sediment of the Delta. To effectively manage this threat, a quantitative understanding of the relative contribution of the different Hg sources to MeHg formation is needed. Mass balance estimates indicate as much as 99% of the Hg entering the Delta arrives via tributary inputs. Of the tributary Hg load, approximately 90% is adsorbed to suspended particles from tributary discharge and 10% is in the dissolved fraction, potentially of atmospheric origin. In comparison, the remaining 1-2% of the Hg entering the Delta arrives through direct atmospheric deposition (wet and dry). The relative importance of these sources to MeHg production within the Delta is not linearly related to the mass inputs because atmospherically-derived Hg is believed to be more reactive than sediment-bound Hg with respect to MeHg formation. We conducted an in situ mesocosm dosing experiment where different Hg sources to the Delta (direct atmospheric, dissolved riverine and suspended sediment) were "labeled" with different stable Hg isotopes and added to mesocosms within four different wetlands. Mercury isotopes added with the streambed sediments were equilibrated in sealed containers for six months; while the Hg isotopes associated with the precipitation and river water were equilibrated for 24 hours prior to use. After adding the isotopes, we sampled the water column, overlying air, bottom sediments and fish (Gambusia) at time intervals up to 30 days. Preliminary results from this experiment suggest that aqueous Hg sources (Hg introduced with precipitation and filtered river water) are 10

  8. Atmospheric Deposition Effects on Plankton Communities in the Eastern Mediterranean: A Mesocosm Experimental Approach

    Directory of Open Access Journals (Sweden)

    Tatiana M. Tsagaraki

    2017-07-01

    Full Text Available The effects of atmospheric deposition on plankton community structure were examined during a mesocosm experiment using water from the Cretan Sea (Eastern Mediterranean, an area with a high frequency of atmospheric aerosol deposition events. The experiment was carried out under spring-summer conditions (May 2012. The main objective was to study the changes induced from a single deposition event, on the autotrophic and heterotrophic surface microbial populations, from viruses to zooplankton. To this end, the effects of Saharan dust addition were compared to the effects of mixed aerosol deposition on the plankton community over 9 days. The effects of the dust addition seemed to propagate throughout the food-web, with changes observed in nearly all of the measured parameters up to copepods. The dust input stimulated increased productivity, both bacterial and primary. Picoplankton, both autotrophic and heterotrophic capitalized on the changes in nutrient availability and microzooplankton abundance also increased due to increased availability of prey. Five days after the simulated deposition, copepods also responded, with an increase in egg production. The results suggest that nutrients were transported up the food web through autotrophs, which were favored by the Nitrogen supplied through both treatments. Although, the effects of individual events are generally short lived, increased deposition frequency and magnitude of events is expected in the area, due to predicted reduction in rainfall and increase in temperature, which can lead to more persistent changes in plankton community structure. Here we demonstrate how a single dust deposition event leads to enhancement of phytoplankton and microzooplankton and can eventually, through copepods, transport more nutrients up the food web in the Eastern Mediterranean Sea.

  9. Annual atmospheric mercury species in downtown Toronto, Canada.

    Science.gov (United States)

    Song, Xinjie; Cheng, Irene; Lu, Julia

    2009-03-01

    Real-time concentrations of atmospheric gaseous elemental mercury (GEM), reactive gaseous mercury (RGM), and mercury associated with particles having sizes RGM were 4.5 +/- 3.1 ng m(-3) (99.2%), 21.5 +/- 16.4 pg m(-3) (0.5%) and 14.2 +/- 13.2 pg m(-3) (0.3%), respectively. The concentrations for all the measured Hg species were highly variable throughout the year and were lower in winter than in the other three seasons. The maximum concentrations of Hg species were observed in June and were a result of the high number of Hg spikes (using [GEM] >10 ng m(-3) as an indicator) that occurred in the month. Nighttime (between 9pm-6am) concentrations of Hg species were higher than those of daytime. The results revealed: (1) an urban area is a continuous source of Hg species that have the potential to pose impacts on local, regional and global scales; (2) local/regional anthropogenic sources contributed significantly to the levels and the distributions of the Hg species in the urban atmosphere. More studies are needed to identify and quantify the anthropogenic sources of Hg and the Hg species emitted from these sources; (3) surface emission and photochemical reactions (including the reactions involving ozone) did not have significant influence on the levels of Hg species and their distribution in the urban atmosphere.

  10. A Heavy Metal Atmospheric Deposition Study in the South Ural Mountains

    CERN Document Server

    Frontasyeva, M V; Steinnes, E; Lyapunov, S M; Cherchintsev, V D

    2002-01-01

    Samples of the mosses Hylocomium splendens and Pleurozium schreberi, collected in the summer of 1998, were used to study the atmospheric deposition of heavy metals and other toxic elements in the Chelyabinsk Region situated in the South Ural, one of the most heavily polluted industrial areas of the Russian Federation. Samples of natural soils were collected simultaneously with moss at the same 30 sites in order to investigate surface accumulation of heavy metals and to examine the correlation of elements in moss and soil samples in order to separate contributions from atmospheric deposition and from soil minerals. A total of 38 elements (Na, Mg, Al, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, As, Se, Rb, Sr, Zr, Mo, Sb, Cs, Ba, La, Ce, Nd, Sm, Eu, Gd, Tb, Dy, Yb, Hf, Ta, W, Au, Th, U) in soil and 33 elements (Na, Mg, Al, Cl, K, Ca, Sc, V, Cr, Mn, Fe, Co, Ni, Zn, As, Se, Br, Rb, Ag, Sb, Cs, Ba, La, Ce, Sm, Tb, Yb, Hf, Ta, W, Au, Th, U) in mosses were determined by epithermal neutron activation analysis. The elem...

  11. Decreased atmospheric sulfur deposition across the southeastern U.S.: When will watersheds release stored sulfate?

    Science.gov (United States)

    Rice, Karen C.; Scanlon, Todd M.; Lynch, Jason A.; Cosby, Bernard J.

    2014-01-01

    Emissions of sulfur dioxide (SO2) to the atmosphere lead to atmospheric deposition of sulfate (SO42-), which is the dominant strong acid anion causing acidification of surface waters and soils in the eastern United States (U.S.). Since passage of the Clean Air Act and its Amendments, atmospheric deposition of SO2 in this region has declined by over 80%, but few corresponding decreases in stream-water SO42- concentrations have been observed in unglaciated watersheds. We calculated SO42- mass balances for 27 forested, unglaciated watersheds from Pennsylvania to Georgia, by using total atmospheric deposition (wet plus dry) as input. Many of these watersheds still retain SO42-, unlike their counterparts in the northeastern U.S. and southern Canada. Our analysis showed that many of these watersheds should convert from retaining to releasing SO42- over the next two decades. The specific years when the watersheds crossover from retaining to releasing SO42- correspond to a general geographical pattern of later net watershed release from north to south. The single most important variable that explained the crossover year was the runoff ratio, defined as the ratio of annual mean stream discharge to precipitation. Percent clay content and mean soil depth were secondary factors in predicting crossover year. The conversion of watersheds from net SO42- retention to release anticipates more widespread reductions in stream-water SO42- concentrations in this region.

  12. Short-term variability of 7Be atmospheric deposition and watershed response in a Pacific coastal stream, Monterey Bay, California, USA

    International Nuclear Information System (INIS)

    Conaway, Christopher H.; Storlazzi, Curt D.; Draut, Amy E.; Swarzenski, Peter W.

    2013-01-01

    Beryllium-7 is a powerful and commonly used tracer for environmental processes such as watershed sediment provenance, soil erosion, fluvial and nearshore sediment cycling, and atmospheric fallout. However, few studies have quantified temporal or spatial variability of 7 Be accumulation from atmospheric fallout, and parameters that would better define the uses and limitations of this geochemical tracer. We investigated the abundance and variability of 7 Be in atmospheric deposition in both rain events and dry periods, and in stream surface-water samples collected over a ten-month interval at sites near northern Monterey Bay (37°N, 122°W) on the central California coast, a region characterized by a rainy winters, dry summers, and small mountainous streams with flashy hydrology. The range of 7 Be activity in rainwater samples from the main sampling site was 1.3–4.4 Bq L −1 , with a mean (±standard deviation) of 2.2 ± 0.9 Bq L −1 , and a volume-weighted average of 2.0 Bq L −1 . The range of wet atmospheric deposition was 18–188 Bq m −2 per rain event, with a mean of 72 ± 53 Bq m −2 . Dry deposition fluxes of 7 Be ranged from less than 0.01 up to 0.45 Bq m −2 d −1 , with an estimated dry season deposition of 7 Bq m −2 month −1 . Annualized 7 Be atmospheric deposition was approximately 1900 Bq m −2 yr −1 , with most deposition via rainwater (>95%) and little via dry deposition. Overall, these activities and deposition fluxes are similar to values found in other coastal locations with comparable latitude and Mediterranean-type climate. Particulate 7 Be values in the surface water of the San Lorenzo River in Santa Cruz, California, ranged from −1 to 0.6 Bq g −1 , with a median activity of 0.26 Bq g −1 . A large storm event in January 2010 characterized by prolonged flooding resulted in the entrainment of 7 Be-depleted sediment, presumably from substantial erosion in the watershed. There were too few particulate 7 Be data over the storm

  13. Forest condition and chemical characteristics of atmospheric depositions: research and monitoring network in Lombardy

    Directory of Open Access Journals (Sweden)

    Flaminio DI GIROLAMO

    2002-09-01

    Full Text Available Since 1987, the Regional Forestry Board of Lombardy and the Water Research Institute of the National Research Council have been carrying out surveys of forest conditions and the response of the ecosystem to environmental factors. The study approach is based on a large number of permanent plots for extensive monitoring (Level 1. At this level, crown condition is assessed annually, and soil condition and the nutritional status of forests surveyed. Some of the permanent plots were selected for intensive monitoring (Level 2, focussing mainly on the impact of atmospheric pollution on forest ecosystems. Level 2 monitoring also includes increment analyses, ground vegetation assessment, atmospheric deposition, soil solution analyses and climatic observations. This paper summarises the main results of a pluriannual research, which provides a general picture of the state of forest health in the region and focuses on more detailed investigations, described as case studies. Modified wet and dry samplers which use a water surface to collect dry deposition were used in a pluriannual field campaign at five sites in alpine and prealpine areas, to measure the total atmospheric depositions and to evaluate the nitrogen and sulphate exceedances of critical loads. Throughfall and bulk precipitation chemistry were studied for five years (June 1994-May 1999 at two high elevation forest sites (Val Gerola and Val Masino which were known to differ in terms of tree health, as assessed by live crown condition. Results indicated a higher contribution from the dry deposition of N-NO3 -, N-NH4 + and H+ and considerable canopy leaching of Ca2+, K+ and weak organic acids at Val Gerola, where the symptoms of damage were more evident. In the area of Val Masino (SO, included since 1997 in the national CONECOFOR network, investigations focused on the effectiveness of the biological compartment in modifying fluxes of atmospheric elements, and on the role of nitrogen both as an

  14. Spatial variation of mercury bioaccumulation in bats of Canada linked to atmospheric mercury deposition.

    Science.gov (United States)

    Chételat, John; Hickey, M Brian C; Poulain, Alexandre J; Dastoor, Ashu; Ryjkov, Andrei; McAlpine, Donald; Vanderwolf, Karen; Jung, Thomas S; Hale, Lesley; Cooke, Emma L L; Hobson, Dave; Jonasson, Kristin; Kaupas, Laura; McCarthy, Sara; McClelland, Christine; Morningstar, Derek; Norquay, Kaleigh J O; Novy, Richard; Player, Delanie; Redford, Tony; Simard, Anouk; Stamler, Samantha; Webber, Quinn M R; Yumvihoze, Emmanuel; Zanuttig, Michelle

    2018-06-01

    Wildlife are exposed to neurotoxic mercury at locations distant from anthropogenic emission sources because of long-range atmospheric transport of this metal. In this study, mercury bioaccumulation in insectivorous bat species (Mammalia: Chiroptera) was investigated on a broad geographic scale in Canada. Fur was analyzed (n=1178) for total mercury from 43 locations spanning 20° latitude and 77° longitude. Total mercury and methylmercury concentrations in fur were positively correlated with concentrations in internal tissues (brain, liver, kidney) for a small subset (n=21) of little brown bats (Myotis lucifugus) and big brown bats (Eptesicus fuscus), validating the use of fur to indicate internal mercury exposure. Brain methylmercury concentrations were approximately 10% of total mercury concentrations in fur. Three bat species were mainly collected (little brown bats, big brown bats, and northern long-eared bats [M. septentrionalis]), with little brown bats having lower total mercury concentrations in their fur than the other two species at sites where both species were sampled. On average, juvenile bats had lower total mercury concentrations than adults but no differences were found between males and females of a species. Combining our dataset with previously published data for eastern Canada, median total mercury concentrations in fur of little brown bats ranged from 0.88-12.78μg/g among 11 provinces and territories. Highest concentrations were found in eastern Canada where bats are most endangered from introduced disease. Model estimates of atmospheric mercury deposition indicated that eastern Canada was exposed to greater mercury deposition than central and western sites. Further, mean total mercury concentrations in fur of adult little brown bats were positively correlated with site-specific estimates of atmospheric mercury deposition. This study provides the largest geographic coverage of mercury measurements in bats to date and indicates that atmospheric

  15. Controlling Factors of Mercury Wet Deposition and Precipitation Concentrations in Upstate New York

    Science.gov (United States)

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

    2017-12-01

    Observations from the Mercury Deposition Network (MDN) at Huntington Wildlife Forest (HWF) suggested that a significant decline in Hg concentrations in precipitation was linked to Hg emission decreases in the United States, especially in the Northeast and Midwest, and yet Hg wet deposition has remained fairly constant over the past two decades. The present study was aimed to investigate how climatic, terrestrial, and anthropogenic factors had influenced the Hg wet deposition flux in upstate New York (NY). To achieve this, an improved Community Multiscale Air Quality (CMAQ) model was employed, which included state-of-the-art Hg and halogen chemistry mechanisms. A base simulation and five sensitivity simulations were conducted. The base simulation used 2010 meteorology, U.S. EPA NEI 2011, and GEOS-Chem output as initial and boundary conditions (ICs and BCs). The five sensitivity runs each changed one condition at the time as follows: 1-3) 2004, 2005, and 2007 meteorology instead of 2010, 4) NEI 2005 Hg anthropogenic emission out of NYS instead of NEI 2011, and 5) no in-state Hg anthropogenic emission. The study period of all the simulations was March - November 2010, and the domain covered the northeastern United States at 12 km resolution. As a result, compared with rural areas in NYS, Hg wet deposition and ambient Hg concentrations in urban areas were affected more significantly by in-state anthropogenic Hg emission. The in-state anthropogenic Hg emissions contributed up to 20% of Hg wet deposition at urban sites and cloud height, precipitation, wind speed and direction, and relative humidity, among which precipitation had the largest effects in most areas. Diluting effects were found in non-convective precipitation, which contributed 31-48% to changes in Hg concentration in precipitation.

  16. Transfer of gaseous iodine (I2) from atmosphere to rice grains through dry deposition

    International Nuclear Information System (INIS)

    Uchida, Shigeo; Muramatsu, Yasuyuki; Sumiya, Misako; Ohmomo, Yoichiro

    1989-01-01

    The report briefly outlines parameters required to determine the transfer of 129 I from the atmosphere to rice grains, and presents results of a study in which the transfer of iodine from the atmosphere to rice grains is calculated using empirically determined parameters. There are four major parameters required for the calculation: (1) the major transfer route (translocation either from leaves or from the surface of hulls to rice grains), (2) rate of deposition onto the surface of leaves or hulls, (3) biological half-life of iodine deposited on leaves or hulls, and (4) either the rate of translocation from leaves to hulls (where the translocation from leaves is the major route) or the ratio of iodine distribution among hulls, unpolished rice grains, and polished rice grains (where the translocation from hulls is the major route). Techniques available to determine the translocation route, deposition rate, biological half-life and distribution ratio are outlined. Chemical forms of iodine, parameters relating to the transfer of gaseous iodine to paddy rice, and calculation models are also described. (N,K.)

  17. Hg0 and HgCl2 Reference Gas Standards: ?NIST Traceability ...

    Science.gov (United States)

    EPA and NIST have collaborated to establish the necessary procedures for establishing the required NIST traceability of commercially-provided Hg0 and HgCl2 reference generators. This presentation will discuss the approach of a joint EPA/NIST study to accurately quantify the true concentrations of Hg0 and HgCl2 reference gases produced from high quality, NIST-traceable, commercial Hg0 and HgCl2 generators. This presentation will also discuss the availability of HCl and Hg0 compressed reference gas standards as a result of EPA's recently approved Alternative Methods 114 and 118. Gaseous elemental mercury (Hg0) and oxidized mercury (HgCl2) reference standards are integral to the use of mercury continuous emissions monitoring systems (Hg CEMS) for regulatory compliance emissions monitoring. However, a quantitative disparity of approximately 7-10% has been observed between commercial Hg0 and HgCl2 reference gases which currently limits the use of (HgCl2) reference gas standards. Resolving this disparity would enable the expanded use of (HgCl2) reference gas standards for regulatory compliance purposes.

  18. Atmospheric pressure plasma enhanced chemical vapor deposition of zinc oxide and aluminum zinc oxide

    International Nuclear Information System (INIS)

    Johnson, Kyle W.; Guruvenket, Srinivasan; Sailer, Robert A.; Ahrenkiel, S. Phillip; Schulz, Douglas L.

    2013-01-01

    Zinc oxide (ZnO) and aluminum-doped zinc oxide (AZO) thin films were deposited via atmospheric pressure plasma enhanced chemical vapor deposition. A second-generation precursor, bis(1,1,1,5,5,5-hexafluoro-2,4-pentanedionato)(N,N′-diethylethylenediamine) zinc, exhibited significant vapor pressure and good stability at one atmosphere where a vaporization temperature of 110 °C gave flux ∼ 7 μmol/min. Auger electron spectroscopy confirmed that addition of H 2 O to the carrier gas stream mitigated F contamination giving nearly 1:1 metal:oxide stoichiometries for both ZnO and AZO with little precursor-derived C contamination. ZnO and AZO thin film resistivities ranged from 14 to 28 Ω·cm for the former and 1.1 to 2.7 Ω·cm for the latter. - Highlights: • A second generation precursor was utilized for atmospheric pressure film growth. • Addition of water vapor to the carrier gas stream led to a marked reduction of ZnF 2 . • Carbonaceous contamination from the precursor was minimal

  19. Control of Toxic Chemicals in Puget Sound, Phase 3: Study of Atmospheric Deposition of Air Toxics to the Surface of Puget Sound

    Energy Technology Data Exchange (ETDEWEB)

    Brandenberger, Jill M.; Louchouarn, Patrick; Kuo, Li-Jung; Crecelius, Eric A.; Cullinan, Valerie I.; Gill, Gary A.; Garland, Charity R.; Williamson, J. B.; Dhammapala, R.

    2010-07-05

    The results of the Phase 1 Toxics Loading study suggested that runoff from the land surface and atmospheric deposition directly to marine waters have resulted in considerable loads of contaminants to Puget Sound (Hart Crowser et al. 2007). The limited data available for atmospheric deposition fluxes throughout Puget Sound was recognized as a significant data gap. Therefore, this study provided more recent or first reported atmospheric deposition fluxes of PAHs, PBDEs, and select trace elements for Puget Sound. Samples representing bulk atmospheric deposition were collected during 2008 and 2009 at seven stations around Puget Sound spanning from Padilla Bay south to Nisqually River including Hood Canal and the Straits of Juan de Fuca. Revised annual loading estimates for atmospheric deposition to the waters of Puget Sound were calculated for each of the toxics and demonstrated an overall decrease in the atmospheric loading estimates except for polybrominated diphenyl ethers (PBDEs) and total mercury (THg). The median atmospheric deposition flux of total PBDE (7.0 ng/m2/d) was higher than that of the Hart Crowser (2007) Phase 1 estimate (2.0 ng/m2/d). The THg was not significantly different from the original estimates. The median atmospheric deposition flux for pyrogenic PAHs (34.2 ng/m2/d; without TCB) shows a relatively narrow range across all stations (interquartile range: 21.2- 61.1 ng/m2/d) and shows no influence of season. The highest median fluxes for all parameters were measured at the industrial location in Tacoma and the lowest were recorded at the rural sites in Hood Canal and Sequim Bay. Finally, a semi-quantitative apportionment study permitted a first-order characterization of source inputs to the atmosphere of the Puget Sound. Both biomarker ratios and a principal component analysis confirmed regional data from the Puget Sound and Straits of Georgia region and pointed to the predominance of biomass and fossil fuel (mostly liquid petroleum products such

  20. Mercury Concentration and Isotopic Composition of Epiphytic Tree Lichens in the Alberta Oil Sands Region

    Science.gov (United States)

    Mercury (Hg) is a toxic heavy metal that is found associated with fossil fuel deposits and that can be released to the atmosphere during fossil fuel combustion and/or processing. Hg emitted to the atmosphere can be deposited to aquatic and terrestrial ecosystems where it can be m...

  1. Deposition of hybrid organic-inorganic composite coatings using an atmospheric plasma jet system.

    Science.gov (United States)

    Dembele, Amidou; Rahman, Mahfujur; Reid, Ian; Twomey, Barry; MacElroy, J M Don; Dowling, Denis P

    2011-10-01

    The objective of this study is to investigate the influence of alcohol addition on the incorporation of metal oxide nanoparticles into nm thick siloxane coatings. Titanium oxide (TiO2) nanoparticles with diameters of 30-80 nm were incorporated into an atmospheric plasma deposited tetramethylorthosilicate (TMOS) siloxane coating. The TMOS/TiO2 coating was deposited using the atmospheric plasma jet system known as PlasmaStream. In this system the liquid precursor/nanoparticle mixture is nebulised into the plasma. It was observed that prior to being nebulised the TiO2 particles agglomerated and settled over time in the TMOS/TiO2 mixture. In order to obtain a more stable nanoparticle/TMOS suspension the addition of the alcohols methanol, octanol and pentanol to this mixture was investigated. The addition of each of these alcohols was found to stabilise the nanoparticle suspension. The effect of the alcohol was therefore assessed with respect to the properties of the deposited coatings. It was observed that coatings deposited from TMOS/TiO2, with and without the addition of methanol were broadly similar. In contrast the coatings deposited with octanol and pentanol addition to the TMOS/TiO2 mixture were significantly thicker, for a given set of deposition parameters and were also more homogeneous. This would indicate that the alcohol precursor was incorporated into the plasma polymerised siloxane. The incorporation of the organic functionality from the alcohols was confirmed from FTIR spectra of the coatings. The difference in behaviour with alcohol type is likely to be due to the lower boiling point of methanol (65 degrees C), which is lower than the maximum plasma temperature measured at the jet orifice (77 degrees C). This temperature is significantly lower than the 196 degrees C and 136 degrees C boiling points of octanol and pentanol respectively. The friction of the coatings was determined using the Pin-on-disc technique. The more organic coatings deposited with

  2. Methylation of Hg downstream from the Bonanza Hg mine, Oregon

    Science.gov (United States)

    Gray, John E.; Hines, Mark E.; Krabbenhoft, David P.; Thoms, Bryn

    2012-01-01

    Speciation of Hg and conversion to methyl-Hg were evaluated in stream sediment, stream water, and aquatic snails collected downstream from the Bonanza Hg mine, Oregon. Total production from the Bonanza mine was >1360t of Hg, during mining from the late 1800s to 1960, ranking it as an intermediate sized Hg mine on an international scale. The primary objective of this study was to evaluate the distribution, transport, and methylation of Hg downstream from a Hg mine in a coastal temperate climatic zone. Data shown here for methyl-Hg, a neurotoxin hazardous to humans, are the first reported for sediment and water from this area. Stream sediment collected from Foster Creek flowing downstream from the Bonanza mine contained elevated Hg concentrations that ranged from 590 to 71,000ng/g, all of which (except the most distal sample) exceeded the probable effect concentration (PEC) of 1060ng/g, the Hg concentration above which harmful effects are likely to be observed in sediment-dwelling organisms. Concentrations of methyl-Hg in stream sediment collected from Foster Creek varied from 11 to 62ng/g and were highly elevated compared to regional baseline concentrations (0.11-0.82ng/g) established in this study. Methyl-Hg concentrations in stream sediment collected in this study showed a significant correlation with total organic C (TOC, R2=0.62), generally indicating increased methyl-Hg formation with increasing TOC in sediment. Isotopic-tracer methods indicated that several samples of Foster Creek sediment exhibited high rates of Hg-methylation. Concentrations of Hg in water collected downstream from the mine varied from 17 to 270ng/L and were also elevated compared to baselines, but all were below the 770ng/L Hg standard recommended by the USEPA to protect against chronic effects to aquatic wildlife. Concentrations of methyl-Hg in the water collected from Foster Creek ranged from 0.17 to 1.8ng/L, which were elevated compared to regional baseline sites upstream and downstream

  3. Monolithic dual-band HgCdTe infrared detector structure

    CSIR Research Space (South Africa)

    Parish, G

    1997-07-01

    Full Text Available A monolithic HgCdTe photoconductive device structure is presented that is suitable for dual-band optically registered infrared photodetection in the two atmospheric transmission windows of 3-5 mu m and 8-12 mu m, which correspond to the mid...

  4. Impact of acid atmospheric deposition on soils : quantification of chemical and hydrologic processes

    NARCIS (Netherlands)

    Grinsven, van J.J.M.

    1988-01-01

    Atmospheric deposition of SO x , NOx and NHx will cause major changes in the chemical composition of solutions in acid soils, which may affect the biological functions of the soil. This thesis deals with quantification of soil acidification by means of chemical

  5. Heavy metal atmospheric deposition study in the South Ural Mountains

    International Nuclear Information System (INIS)

    Frontasyeva, M.V.; Smirnov, L.I.; Lyapunov, S.M.

    2004-01-01

    Samples of the mosses Hylocomium splendens and Pleurozium schreberi, collected in the summer of 1998, were used to study the atmospheric deposition of heavy metals and other toxic elements in the Chelyabinsk Region situated in the South Urals, one of the most heavily polluted industrial areas of the Russian Federation. Samples of natural soils were collected simultaneously with moss at the same 30 sites in order to investigate surface accumulation of heavy metals and to examine the correlation of elements in moss and soil samples in order to separate contributions from atmospheric deposition and from soil minerals. A total of 38 elements (Na, Mg, Al, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, As, Se, Rb, Sr, Zr, Mo, Sb, Cs, Ba, La, Ce, Nd, Sm, Eu, Gd, Tb, Dy, Yb, Hf, Ta, W, Au, Th, U) in soil and 33 elements Na, Mg, Al, Cl, K, Ca, Sc, V, Cr, Mn, Fe, Co, Ni, Zn, As, Se, Br, Rb, Ag, Sb, Cs, Ba, La, Ce, Sm, Tb, Yb, Hf, Ta, W, Au, Th, U) were determined by epithermal neutron activation analysis. The elements Cu, Cd and Pb (in moss samples only) were obtained by atomic absorption spectrometry. VARIMAX rotated principal component analysis was used to identify and characterize different pollution sources and to point out the most polluted areas. (author)

  6. Atmospheric Deposition of Trace Elements Around Ulan-Bator City Studied by Moss and Lichen Biomonitoring Technique and INAA

    CERN Document Server

    Ganbold, G; Gundorina, S F; Frontasyeva, M V; Ostrovnaya, T M; Pavlov, S S; Tsendeekhuu, T

    2005-01-01

    For the first time the moss and lichen biomonitoring technique has been applied to air pollution in Mongolia (Ulan-Bator, the capital city). INAA at the IBR-2 reactor has made it possible to determine the content of 35 elements in moss and lichen biomonitors. Samples collected at sites located 10-15 km from the center of Ulan-Bator were analyzed by Instrumental Neutron Activation Analysis (INAA) using epithermal neutrons. The mosses (\\textit{Rhytidium rugosum}, \\textit{Thuidium abietinum}, \\textit{Entodon concinnus}) and lichens (\\textit{Cladonia stellaris}, \\textit{Parmelia separata}) were used to study the atmospheric deposition of trace elements. It was shown that the suggested types of mosses could be used as suitable biomonitors to estimate the concentration levels of heavy metals and trace elements in Ulan-Bator atmospheric deposition. The results are compared to the data of atmospheric deposition of some European countries.

  7. Source discrimination of atmospheric metal deposition by multi-metal isotopes in the Three Gorges Reservoir region, China.

    Science.gov (United States)

    Liu, Jinling; Bi, Xiangyang; Li, Fanglin; Wang, Pengcong; Wu, Jin

    2018-05-12

    Concentrations of heavy metals, as well as isotopic compositions of mercury (Hg) and lead (Pb), in mosses (Bryum argenteum) from the Three Gorges Reservoir (TGR) region were investigated to decipher the sources of atmospheric metals in this region. Higher contents of metals (0.90 ± 0.65 mg/kg of Cd, 24.6 ± 27.4 mg/kg of Cu, and 36.1 ± 51.1 mg/kg of Pb) in the mosses from TGR were found compared with those from pollution-free regions. Principal component analysis (PCA) grouped the moss metals into four main components which were associated with both anthropogenic and natural sources. The ratios of Pb isotopes of the mosses (1.153-1.173 for 206 Pb/ 207 Pb and 2.094-2.129 for 208 Pb/ 206 Pb) fell between those of the traffic emissions and coals. Similarly, the compositions of δ 202 Hg (-4.29∼-2.33‰) and Δ 199 Hg (within ±0.2‰) were comparable to those of the coals and coal combustion emissions from China and India. These joined results of Pb and Hg isotope data give solid evidences that the coal combustion and traffic emissions are the main causes of metal accumulation in the TGR region. Copyright © 2018 Elsevier Ltd. All rights reserved.

  8. Atmospheric Energy Deposition Modeling and Inference for Varied Meteoroid Structures

    Science.gov (United States)

    Wheeler, Lorien; Mathias, Donovan; Stokan, Edward; Brown, Peter

    2018-01-01

    Asteroids populations are highly diverse, ranging from coherent monoliths to loosely-bound rubble piles with a broad range of material and compositional properties. These different structures and properties could significantly affect how an asteroid breaks up and deposits energy in the atmosphere, and how much ground damage may occur from resulting blast waves. We have previously developed a fragment-cloud model (FCM) for assessing the atmospheric breakup and energy deposition of asteroids striking Earth. The approach represents ranges of breakup characteristics by combining progressive fragmentation with releases of variable fractions of debris and larger discrete fragments. In this work, we have extended the FCM to also represent asteroids with varied initial structures, such as rubble piles or fractured bodies. We have used the extended FCM to model the Chelyabinsk, Benesov, Kosice, and Tagish Lake meteors, and have obtained excellent matches to energy deposition profiles derived from their light curves. These matches provide validation for the FCM approach, help guide further model refinements, and enable inferences about pre-entry structure and breakup behavior. Results highlight differences in the amount of small debris vs. discrete fragments in matching the various flare characteristics of each meteor. The Chelyabinsk flares were best represented using relatively high debris fractions, while Kosice and Benesov cases were more notably driven by their discrete fragmentation characteristics, perhaps indicating more cohesive initial structures. Tagish Lake exhibited a combination of these characteristics, with lower-debris fragmentation at high altitudes followed by sudden disintegration into small debris in the lower flares. Results from all cases also suggest that lower ablation coefficients and debris spread rates may be more appropriate for the way in which debris clouds are represented in FCM, offering an avenue for future model refinement.

  9. Lichens as biomonitors of atmospheric ammonium/ammonia deposition in Portugal

    International Nuclear Information System (INIS)

    Capelao, A.L.; Maguas, C.; Branquinho, C.; Cruz, C.; Martins-Loucao, M.A.

    2000-01-01

    The aim of the present work was to evaluate the potentiality of lichens as biomonitors of NH 4 + /NH 3 (ammonium/ammonia) and NO 3 - (nitrate) atmospheric deposition. For that, we used as a field station a rice plantation which is submitted, once a year, to air spraying fertilization with a mixture of nitrogen sources. Samples of an epiphytic lichen, Ramalina fastigiata, were collected from an ash-tree bordering the rice-plantation by the Sorraia River Valley (Central Portugal). The study started one month before fertilization and sampling was carried out for five months. The concentration of ammonium in the lichen was highly and significantly correlated with the number of days without precipitation before sampling, and had an inverse correlation with fluorescence values. Under these conditions, the amount of NH 4 + found in the lichen appears to reflect ammonium/ammonia dry deposition. (author)

  10. Diurnal and seasonal variability in size-dependent atmospheric deposition fluxes of polycyclic aromatic hydrocarbons in an urban center

    Science.gov (United States)

    Zhang, Kai; Zhang, Bao-Zhong; Li, Shao-Meng; Zhang, Lei-Ming; Staebler, Ralf; Zeng, Eddy Y.

    2012-09-01

    Atmospheric gaseous and size-segregated particle samples were collected from urban Guangzhou at the heights of 100 and 150 m above the ground in daytime and at night in August and December 2010, and were analyzed for polycyclic aromatic hydrocarbons (PAHs). Particulate PAHs were more abundant at night than in daytime, and significantly higher in winter than in summer. The observed vertical, diurnal, and seasonal variability in the occurrences of PAH were attributed to varying meteorological conditions and atmospheric boundary layers. More than 60% of the particulate PAHs were contained in particles in the accumulation mode with an aerodynamic diameter (Dp) in the range of 0.1-1.8 μm. Different mass transfer velocities by volatilization and condensation are considered the main causes for the different particle size distributions among individual PAHs, while combustion at different temperatures and atmospheric transport were probable causes of the observed seasonal variation in the size distribution of PAHs. Based on the modeled size-dependent dry deposition velocities, daily mean dry deposition fluxes of particulate PAHs ranged from 604 to 1190 ng m-2 d-1, with PAHs in coarse particles (Dp > 1.8 μm) accounting for 55-95% of the total fluxes. In addition, gaseous PAHs were estimated to contribute 0.6-3.1% to the total dry deposition fluxes if a conservative dry deposition velocity for gaseous species (2 × 10-4 m s-1) were used. Finally, disequilibrium phase partitioning, meteorological conditions and atmospheric transport were regarded as the main reasons for the variances in dry deposition velocities of individual PAHs.

  11. Dynamic modelling of atmospherically-deposited Ni, Cu, Zn, Cd and Pb in Pennine catchments (northern England)

    International Nuclear Information System (INIS)

    Tipping, E.; Rothwell, J.J.; Shotbolt, L.; Lawlor, A.J.

    2010-01-01

    Simulation modelling with CHUM-AM was carried out to investigate the accumulation and release of atmospherically-deposited heavy metals (Ni, Cu, Zn, Cd and Pb) in six moorland catchments, five with organic-rich soils, one with calcareous brown earths, in the Pennine chain of northern England. The model considers two soil layers and a third layer of weathering mineral matter, and operates on a yearly timestep, driven by deposition scenarios covering the period 1400-2010. The principal processes controlling heavy metals are competitive solid-solution partitioning of solutes, chemical interactions in solution, and chemical weathering. Agreement between observed and simulated soil metal pools and surface water concentrations for recent years was generally satisfactory, the results confirming that most contemporary soil metal is from atmospheric pollution. Metals in catchments with organic-rich soils show some mobility, especially under more acid conditions, but the calcareous mineral soils have retained nearly all anthropogenic metal inputs. Complexation by dissolved organic matter and co-transport accounts for up to 80% of the Cu in surface waters. - CHUM-AM is applied to six differing moorland catchments to account for the accumulation and leaching of atmospherically-deposited trace metals over the past several centuries.

  12. Dynamic modelling of atmospherically-deposited Ni, Cu, Zn, Cd and Pb in Pennine catchments (northern England)

    Energy Technology Data Exchange (ETDEWEB)

    Tipping, E., E-mail: et@ceh.ac.u [Centre for Ecology and Hydrology, Lancaster Environment Centre, Library Avenue, Bailrigg, Lancaster LA1 4AP (United Kingdom); Rothwell, J.J. [Upland Environments Research Unit, School of Environment and Development, University of Manchester, Manchester M13 9PL (United Kingdom); Shotbolt, L. [Geography Department, Queen Mary, University of London, Mile End Road, London E1 4NS (United Kingdom); Lawlor, A.J. [Centre for Ecology and Hydrology, Lancaster Environment Centre, Library Avenue, Bailrigg, Lancaster LA1 4AP (United Kingdom)

    2010-05-15

    Simulation modelling with CHUM-AM was carried out to investigate the accumulation and release of atmospherically-deposited heavy metals (Ni, Cu, Zn, Cd and Pb) in six moorland catchments, five with organic-rich soils, one with calcareous brown earths, in the Pennine chain of northern England. The model considers two soil layers and a third layer of weathering mineral matter, and operates on a yearly timestep, driven by deposition scenarios covering the period 1400-2010. The principal processes controlling heavy metals are competitive solid-solution partitioning of solutes, chemical interactions in solution, and chemical weathering. Agreement between observed and simulated soil metal pools and surface water concentrations for recent years was generally satisfactory, the results confirming that most contemporary soil metal is from atmospheric pollution. Metals in catchments with organic-rich soils show some mobility, especially under more acid conditions, but the calcareous mineral soils have retained nearly all anthropogenic metal inputs. Complexation by dissolved organic matter and co-transport accounts for up to 80% of the Cu in surface waters. - CHUM-AM is applied to six differing moorland catchments to account for the accumulation and leaching of atmospherically-deposited trace metals over the past several centuries.

  13. Assessing the natural recovery of a lake contaminated with Hg using estimated recovery rates determined by sediment chronologies

    International Nuclear Information System (INIS)

    Parsons, Matthew J.; Long, David T.; Yohn, Sharon S.

    2010-01-01

    increasing after 1997. The cause of the recent Hg concentrations may be related to influx of contaminated watershed soils or sediments. Estimating the time frame for recovery is challenging in this system because the process of natural recovery seems to have been arrested and deeper, uncontaminated sediments, were not recovered as a basis for reference. However, a recovery to background conditions is likely not achievable since rates of Hg loading to nearby lakes and the current rate of atmospheric deposition are greater than an estimate of background conditions for Deer Lake. Assuming recovery continued after 2000, estimates of the time required for recovery varied based on the system state used to define it (e.g., recent rates of wet Hg deposition or Hg surface concentrations/fluxes from similar systems), but were less than 12 a. However, the recent increasing values of recovery indicators (e.g., Hg concentrations) suggests that these estimates are conservative and will be longer if recovery remains arrested, which may in part be due to the legacy of Hg contamination on the landscape. This study shows that estimates of recovery of highly disturbed lake systems can be made in the absence of within lake reference conditions by using comparisons to reference systems and challenges of estimating ages from atypical 210 Pb activity profiles can be overcome in part using event-based dating techniques.

  14. Assessing the natural recovery of a lake contaminated with Hg using estimated recovery rates determined by sediment chronologies

    Energy Technology Data Exchange (ETDEWEB)

    Parsons, Matthew J. [Michigan State University, Department of Geological Sciences, 206 Natural Science, East Lansing, MI 48824 (United States); Long, David T., E-mail: long@msu.edu [Michigan State University, Department of Geological Sciences, 206 Natural Science, East Lansing, MI 48824 (United States); Yohn, Sharon S. [Juniata College, Raystown Field Station, Brumbaugh Academic Center, Huntingdon, PA 16652 (United States)

    2010-11-15

    their peak, remain elevated, and were increasing after 1997. The cause of the recent Hg concentrations may be related to influx of contaminated watershed soils or sediments. Estimating the time frame for recovery is challenging in this system because the process of natural recovery seems to have been arrested and deeper, uncontaminated sediments, were not recovered as a basis for reference. However, a recovery to background conditions is likely not achievable since rates of Hg loading to nearby lakes and the current rate of atmospheric deposition are greater than an estimate of background conditions for Deer Lake. Assuming recovery continued after 2000, estimates of the time required for recovery varied based on the system state used to define it (e.g., recent rates of wet Hg deposition or Hg surface concentrations/fluxes from similar systems), but were less than 12 a. However, the recent increasing values of recovery indicators (e.g., Hg concentrations) suggests that these estimates are conservative and will be longer if recovery remains arrested, which may in part be due to the legacy of Hg contamination on the landscape. This study shows that estimates of recovery of highly disturbed lake systems can be made in the absence of within lake reference conditions by using comparisons to reference systems and challenges of estimating ages from atypical {sup 210}Pb activity profiles can be overcome in part using event-based dating techniques.

  15. 196Hg and 202Hg isotopic ratios in chondrites: revisited

    International Nuclear Information System (INIS)

    Jovanovic, S.; Reed, G.W. Jr.

    1976-01-01

    Additional evidence for an isotopically anomalous Hg fraction in unequilibrated meteorites has been obtained using neutron activation to produce 196 Hg and 202 Hg followed by stepwise heating to extract the Hg. In the latest experiments Allende matrix samples released the anomalous Hg but various high-temperature inclusions did not. Nucleogenetic processes are suggested as the probable cause of the anomaly. (Auth.)

  16. Cavity ring-down spectroscopy (CRDS) system for measuring atmospheric mercury using differential absorption

    Science.gov (United States)

    Pierce, A.; Obrist, D.; Moosmuller, H.; Moore, C.

    2012-04-01

    Atmospheric elemental mercury (Hg0) is a globally pervasive element that can be transported and deposited to remote ecosystems where it poses — particularly in its methylated form — harm to many organisms including humans. Current techniques for measurement of atmospheric Hg0 require several liters of sample air and several minutes for each analysis. Fast-response (i.e., 1 second or faster) measurements would improve our ability to understand and track chemical cycling of mercury in the atmosphere, including high frequency Hg0 fluctuations, sources and sinks, and chemical transformation processes. We present theory, design, challenges, and current results of our new prototype sensor based on cavity ring-down spectroscopy (CRDS) for fast-response measurement of Hg0 mass concentrations. CRDS is a direct absorption technique that implements path-lengths of multiple kilometers in a compact absorption cell using high-reflectivity mirrors, thereby improving sensitivity and reducing sample volume compared to conventional absorption spectroscopy. Our sensor includes a frequency-doubled, dye-laser emitting laser pulses tunable from 215 to 280 nm, pumped by a Q-switched, frequency tripled Nd:YAG laser with a pulse repetition rate of 50 Hz. We present how we successfully perform automated wavelength locking and stabilization of the laser to the peak Hg0 absorption line at 253.65 nm using an external isotopically-enriched mercury (202Hg0) cell. An emphasis of this presentation will be on the implementation of differential absorption measurement whereby measurements are alternated between the peak Hg0 absorption wavelength and a nearby wavelength "off" the absorption line. This can be achieved using a piezo electric tuning element that allows for pulse-by-pulse tuning and detuning of the laser "online" and "offline" of the Hg absorption line, and thereby allows for continuous correction of baseline extinction losses. Unexpected challenges with this approach included

  17. Variability of atmospheric depositions of artificial radioelements and their transfer into soils

    International Nuclear Information System (INIS)

    Pourcelot, Laurent

    2008-01-01

    In this Habilitation thesis, I present the results and prospects of the main research topics that contribute to bettering our knowledge of the behaviour of artificial radioelements in the geosphere and biosphere. In the first chapter I present a summary of the research carried out for my thesis on the Oklo reactors. In the subsequent chapters I present my research work at the IRSN. The second chapter concerns the atmospheric depositions of radioactive contaminants. I have studied the principal environmental parameters involved in the empirical modelling of the transfer of artificial radioelements from the atmosphere to the soil. Here I essentially use measurements of artificial radioelements ( 137 Cs, plutonium, americium) in soils that reveal the variability of accidental depositions further to the Chernobyl disaster (paragraph 2.1) and chronic radioactive depositions coming from the atmospheric testing of nuclear weapons (paragraph 2.2). In the third chapter I address the problem of transfers of artificial radioelements into the soil. The interest of this lies in the fact that these transfers represent serious risks for man. Taken over the long term (in the months and years that follow the depositing of radioactive elements on the ground and plants), the transfers of radioactive pollutants into the soil are responsible for the contamination of both plants (transfer via the roots) and underground water and surface water (transfer after vertical migration). My research work into the transfers of radioactive pollutants in soils is centred on vertical migrations and root transfers, as both these processes can be studied through environmental samplings and measurements. More precisely, I have studied the migrations of radioactive pollutants and their geochemical analogues in different types of soils (paragraph 3.1) and the variability of the activities of radiostrontium and radiocesium in the compartments of permanent grassland zones (soil, grass, milk and cheese

  18. Acid Deposition Phenomena

    International Nuclear Information System (INIS)

    Ramadan, A.E.K.

    2004-01-01

    Acid deposition, commonly known as acid rain, occurs when emissions from the combustion of fossil fuels and other industrial processes undergo complex chemical reactions in the atmosphere and fall to the earth as wet deposition (rain, snow, cloud, fog) or dry deposition (dry particles, gas). Rain and snow are already naturally acidic, but are only considered problematic when less than a ph of 5.0 The main chemical precursors leading to acidic conditions are atmospheric concentrations of sulfur dioxide (SO 2 ) and nitrogen oxides (NO x ). When these two compounds react with water, oxygen, and sunlight in the atmosphere, the result is sulfuric (H 2 SO 4 ) and nitric acids (HNO 3 ), the primary agents of acid deposition which mainly produced from the combustion of fossil fuel and from petroleum refinery. Airborne chemicals can travel long distances from their sources and can therefore affect ecosystems over broad regional scales and in locations far from the sources of emissions. According to the concern of petroleum ministry with the environment and occupational health, in this paper we will discussed the acid deposition phenomena through the following: Types of acidic deposition and its components in the atmosphere Natural and man-made sources of compounds causing the acidic deposition. Chemical reactions causing the acidic deposition phenomenon in the atmosphere. Factors affecting level of acidic deposition in the atmosphere. Impact of acid deposition. Procedures for acidic deposition control in petroleum industry

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

    Directory of Open Access Journals (Sweden)

    J. D. Hegarty

    2008-03-01

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

  20. Challenges in tracing the fate and effects of atmospheric polycyclic aromatic hydrocarbon deposition in vascular plants.

    Science.gov (United States)

    Desalme, Dorine; Binet, Philippe; Chiapusio, Geneviève

    2013-05-07

    Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous organic pollutants that raise environmental concerns because of their toxicity. Their accumulation in vascular plants conditions harmful consequences to human health because of their position in the food chain. Consequently, understanding how atmospheric PAHs are taken up in plant tissues is crucial for risk assessment. In this review we synthesize current knowledge about PAH atmospheric deposition, accumulation in both gymnosperms and angiosperms, mechanisms of transfer, and ecological and physiological effects. PAHs emitted in the atmosphere partition between gas and particulate phases and undergo atmospheric deposition on shoots and soil. Most PAH concentration data from vascular plant leaves suggest that contamination occurs by both direct (air-leaf) and indirect (air-soil-root) pathways. Experimental studies demonstrate that PAHs affect plant growth, interfering with plant carbon allocation and root symbioses. Photosynthesis remains the most studied physiological process affected by PAHs. Among scientific challenges, identifying specific physiological transfer mechanisms and improving the understanding of plant-symbiont interactions in relation to PAH pollution remain pivotal for both fundamental and applied environmental sciences.

  1. Atmospheric deposition of nitrogen at five subtropical forested sites in South China

    International Nuclear Information System (INIS)

    Chen, Xi Yun; Mulder, Jan

    2007-01-01

    Elevated concentrations of reactive nitrogen (N) in precipitation have been reported for many cities in China. Due to increased use of fossil fuels and expansion in agriculture, further increases in deposition of ammonia (NH x ) and reactive N oxides (NO y ) are predicted. Increased deposition of reactive N is likely to affect N dynamics and N runoff in forest ecosystems. Yet, in China little work has been done to quantify the levels of atmospheric N deposition in such systems. Here, we assess the deposition of inorganic N (ammonium, NH 4 + and nitrate, NO 3 - ) for five subtropical forest ecosystems in remote and urban areas of South China. Annual volume-weighted concentrations in bulk precipitation range from 0.18 to 1.55 mg NH 4 + -N L - 1 and from 0.12 to 0.74 mg NO 3 - -N L - 1 . These values are large and several times greater than those reported for remote sites of the world. The fluxes of total inorganic N (TIN) in wet-only deposition range from 0.8 to 2.3 g N m - 2 yr - 1 , with NH 4 + -N contributing 54% to 77%. Both the tree canopy and the ground vegetation layer are important in determining the net N flux reaching the forest floor, but the net effect varies from site to site. At TieShanPing (TSP), close to Chongqing city, and at CaiJiaTang (CJT), near Shaoshan (Hunan province), the canopy represents a net source of N, probably due to dry deposition. At the other three sites (LiuChongGuan (LCG), LeiGongShan (LGS), both in Guizhou province, and LiuXiHe (LXH) in Guangdong), a net loss of reactive N from precipitation water occurs in the canopy, probably due to uptake processes. The total annual atmospheric TIN load is estimated to range from at least 0.8 g N m - 2 yr - 1 to 4.0 g N m - 2 yr - 1 , with a considerable contribution from dry deposition. Concentrations and fluxes of inorganic N in tree canopy throughfall are greater than those in North America. Also the contribution of NH 4 + -N to TIN fluxes in throughfall (40% to 70%) is greater than in North

  2. Mercury profiles in sediment from the marginal high of Arabian Sea: an indicator of increasing anthropogenic Hg input.

    Science.gov (United States)

    Chakraborty, Parthasarathi; Vudamala, Krushna; Chennuri, Kartheek; Armoury, Kazip; Linsy, P; Ramteke, Darwin; Sebastian, Tyson; Jayachandran, Saranya; Naik, Chandan; Naik, Richita; Nath, B Nagender

    2016-05-01

    Total Hg distributions and its speciation were determined in two sediment cores collected from the western continental marginal high of India. Total Hg content in the sediment was found to gradually increase (by approximately two times) towards the surface in both the cores. It was found that Hg was preferentially bound to sulfide under anoxic condition. However, redox-mediated reactions in the upper part of the core influenced the total Hg content in the sediment cores. This study suggests that probable increase in authigenic and allogenic Hg deposition attributed to the increasing Hg concentration in the surface sediment in the study area.

  3. Mercury in the atmosphere, snow and melt water ponds in the North Atlantic Ocean during Arctic summer.

    Science.gov (United States)

    Aspmo, Katrine; Temme, Christian; Berg, Torunn; Ferrari, Christophe; Gauchard, L Pierre-Alexis; Fain, Xavier; Wibetoe, Grethe

    2006-07-01

    Atmospheric mercury speciation measurements were performed during a 10 week Arctic summer expedition in the North Atlantic Ocean onboard the German research vessel RV Polarstern between June 15 and August 29, 2004. This expedition covered large areas of the North Atlantic and Arctic Oceans between latitudes 54 degrees N and 85 degrees N and longitudes 16 degrees W and 16 degrees E. Gaseous elemental mercury (GEM), reactive gaseous mercury (RGM) and mercury associated with particles (Hg-P) were measured during this study. In addition, total mercury in surface snow and meltwater ponds located on sea ice floes was measured. GEM showed a homogeneous distribution over the open North Atlantic Ocean (median 1.53 +/- 0.12 ng/m3), which is in contrast to the higher concentrations of GEM observed over sea ice (median 1.82 +/- 0.24 ng/m3). It is hypothesized that this results from either (re-) emission of mercury contained in snow and ice surfaces that was previously deposited during atmospheric mercury depletion events (AMDE) in the spring or evasion from the ocean due to increased reduction potential at high latitudes during Arctic summer. Measured concentrations of total mercury in surface snow and meltwater ponds were low (all samples RGM and Hg-P without a significant diurnal variability. These results indicate that the production and deposition of these reactive mercury species do not significantly contribute to the atmospheric mercury cycle in the North Atlantic Ocean during the Arctic summer.

  4. Deposition rates of atmospheric particulates determined from 210Pb measurements in soils and air

    International Nuclear Information System (INIS)

    Likuku, A. S.; Branford, D.

    2011-01-01

    Deposition rates of atmospheric particles were determined using previously published 210P b data in soils and air. The dry deposition velocities for moorland and woodland soils were 2.2 ± 1.8 and 9 ± 2 mm · s - 1 , respectively. The 210P b concentration in rain was calculated to be 94 ± 10 mBq · L - 1. The large (∼ 4 times) deposition velocities in woodland relative to moorland soils is an indication of the degree of accumulation of particles, and most possibly contaminants within woodland soils, which is of practical importance in the mitigation of pollutant concentrations in urban areas by planting trees. (authors)

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

    Czech Academy of Sciences Publication Activity Database

    Navrátil, Tomáš; Shanley, J.; Rohovec, Jan; Oulehle, F.; Krám, P.; Matoušková, Šárka; Tesař, Miroslav; Hojdová, Maria

    2015-01-01

    Roč. 158, November (2015), s. 201-211 ISSN 0375-6742 R&D Projects: GA ČR(CZ) GAP210/11/1369 Institutional support: RVO:67985831 ; RVO:67985874 Keywords : Black Triangle * DOC quality * Filtered Hg * Hg/DOC ratio * Runoff fluxes * Seasonal changes * SUVA Subject RIV: DD - Geochemistry; DA - Hydrology ; Limnology (UH-J) Impact factor: 2.147, year: 2015

  6. Application of a rule-based model to estimate mercury exchange for three background biomes in the continental United States

    Science.gov (United States)

    Hartman, J.S.; Weisberg, P.J.; Pillai, R.; Ericksen, J.A.; Kuiken, T.; Lindberg, S.E.; Zhang, H.; Rytuba, J.J.; Gustin, M.S.

    2009-01-01

    Ecosystems that have low mercury (Hg) concentrations (i.e., not enriched or impactedbygeologic or anthropogenic processes) cover most of the terrestrial surface area of the earth yet their role as a net source or sink for atmospheric Hg is uncertain. Here we use empirical data to develop a rule-based model implemented within a geographic information system framework to estimate the spatial and temporal patterns of Hg flux for semiarid deserts, grasslands, and deciduous forests representing 45% of the continental United States. This exercise provides an indication of whether these ecosystems are a net source or sink for atmospheric Hg as well as a basis for recommendation of data to collect in future field sampling campaigns. Results indicated that soil alone was a small net source of atmospheric Hg and that emitted Hg could be accounted for based on Hg input by wet deposition. When foliar assimilation and wet deposition are added to the area estimate of soil Hg flux these biomes are a sink for atmospheric Hg. ?? 2009 American Chemical Society.

  7. Phase transition study in a [Cu2 HgI4:0⋅xAgI] mixed composite system

    Indian Academy of Sciences (India)

    Administrator

    Diffraction, thermal analysis of compound, Ag2HgI4,. Cu2HgI4, Tl2HgI4 ... nitrogen atmosphere (200 ml/min) at a heating rate of. 5°C per min and a ..... Bates J B and Farington G C 1981 Proceedings of the interna- tional conference on fast ...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1979-06-01

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

  9. Source, flux and balance of atmospheric deposition of metals at Ile-de-France; Source, flux et bilan des retombees atmospheriques de metaux en Ile de France

    Energy Technology Data Exchange (ETDEWEB)

    Azimi, S

    2004-07-15

    The urban atmosphere is submitted to large inputs of anthropogenic contaminants arising from both stationary (power plants, industries, etc.) and mobile (road traffic) sources. These small particles may be transported over long distances and affect ecosystems. Significant dry and wet atmospheric deposition also occurs locally and contributes to the contamination of urban runoff. The aim of this study is to compare heavy metal and hydrocarbon atmospheric deposition fluxes to other input ways on agricultural and urban areas to assess their importance. Moreover, a source investigation has been done to identify the main origins of these pollutants. Before the quantification of pollutant fluxes, a comparison of several sampling procedures was performed. As a result, the sampling of total atmospheric deposition is not affected by the funnel material (Teflon and polyethylene) or by the sampling duration (7 and 28 days). However, the rinsing step of the funnel walls showed a higher relative importance during short sampling periods. The relative amount contained in these solutions reached 24 to 40 % of the total flux during weekly sampling periods and 8 to 18 % during monthly sampling periods, whatever the element considered. The temporal evolution of atmospheric deposition showed no seasonal influence on flux variations during the 2001-2002 period. Considering an 8-year period behaviour, between 1994 and 2002, a significant decrease of the deposition fluxes of Cd, Cu, Pb and Zn occurred at the Creteil site which is placed in an industrialized area of the Paris suburb. The decreasing factor reached 16, 2.5, 4 and 7.5 for these elements respectively. At the Ile-de-France scale, the deposition flux levels on urban and semi-urban areas were of the same order of magnitude (?20 tonnes per year for Ba, Cu, Pb and Sr). Since semi-urban surface area is four times higher than urban ones, the important influence of anthropogenic activities on atmospheric deposition of urban areas is

  10. Mercury-cycling in surface waters and in the atmosphere - species analysis for the investigation of transformation and transport properties of mercury

    International Nuclear Information System (INIS)

    Ebinghaus, R.; Hintelmann, H.; Wilken, R.D.

    1994-01-01

    The river Elbe has been one of the most contaminated rivers with regard to mercury for many years. In 1991 a length-profile has been measured for mercury and methylmercury (CH 3 Hg + ) from Obristvi, Czech Republic, to the German bight. Total mercury has been measured by cold vapor atomic absorption spectrometry (CVAAS). The organo mercury compounds have been separated by high performance liquid chromatography (HPLC) connected on-line to an atomic fluorescence spectrometer (AFS) by a continuous flow-system. Total mercury up to 120 mg Hg + /kg and CH 3 Hg + concentrations up to 130 μg CH 3 Hg + /kg could be detected in special sites. The formation of CH 3 Hg + in sediments can be caused besides the methylation of mercury, by sulphate reducing or methanogenic bacteria and transmethylation reactions with organometals. Atmospheric mercury concentrations have been measured at three different European sites. Samples have been collected on gold-coated glass balls or on quartz wool, respectively. After thermal desorption mercury has been determined using the two step amalgamation technique with AFS detection. Compared to natural background concentrations of total gaseous mercury (TGM), slightly increased levels could be detected at a rural site in Germany. This increase can probably be explained by long-range transport processes. Within the vicinity of a inactivated mercury production plant high concentrations of up to 13.5 ng/m 3 particle associated mercury (Hg part ) have been detected. Consequently, dry deposition of mercury in the particulate form can intensify the total deposition flux close to Hg-emitting sources. (orig.)

  11. A thermodynamic stability of bulk and epitaxial CdHgTe, ZnHgTe and MnHgTe solid solutions

    International Nuclear Information System (INIS)

    Dejbuk, V.G.; Dremlyuzhenko, S.G.; Ostapov, S.Eh.

    2005-01-01

    A thermodynamics of Cd 1-x Hg x Te, Zn x Hg 1-x Te and Mg x Hg 1-x Te alloys has been investigated for a delta-lattice parameter model. The phase diagrams obtained show the stability of Cd 1-x Hg x Te, Zn x Hg 1-x Te in the whole range of compositions, alongside with a miscibility gap for Mn x Hg 1-x Te being of 0.35 x Hg 1-x Te/CdTe and Mn x Hg 1-x Te/Cd 0.96 Zn 0.04 Te epitaxial films result in lowering critical temperatures and narrowing the miscibility gap [ru

  12. New system for vacuum deposition of refractory materials using an atmospheric-pressure inductively coupled plasma

    International Nuclear Information System (INIS)

    Merkle, B.D.; Kniseley, R.N.; Schmidt, F.A.

    1987-01-01

    We have successfully developed a technique utilizing an atmospheric-pressure inductively coupled plasma combined with a low-pressure deposition chamber for deposition of thin films. The equipment and method of operation are discussed. Refractory powders (Nb and Y 2 O 3 ) were injected into the plasma and deposited as Nb and substoichiometric yttrium oxide, YO/sub 1.49/, onto Fe and Cu substrates. The substoichiometric yttrium oxide deposit adhered well to the Fe and Cu substrates, while the Nb deposit adhered well to the Fe only. The Nb deposit on the Cu substrate flaked and peeled probably because of stresses induced from the thermal expansion mismatch between the Nb and Cu. Further studies will be undertaken to better understand the processes occurring in this type of plasma-coating system in order to optimize the instrumental parameters for particular coating applications

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

    Science.gov (United States)

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

    2016-05-01

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

  14. Atmospheric deposition, resuspension and root uptake of plutonium in corn and other grain-producing agroecosystems near a nuclear fuel facility

    International Nuclear Information System (INIS)

    Pinder, J.E. III; McLeod, K.W.; Adriano, D.C.; Corey, J.C.; Boni, A.L.

    1989-01-01

    Plutonium released to the environment may contribute to dose to humans through inhalation or ingestion of contaminated foodstuffs. Plutonium contamination of agricultural plants may result from interception and retention of atmospheric deposition, resuspension of Pu-bearing soil particles to plant surfaces, and root uptake and translocation to grain. Plutonium on vegetation surfaces may be transferred to grain surfaces during mechanical harvesting. Data obtained from corn grown near the US Department of Energy's H-Area nuclear fuel chemical separations facility on the Savannah River Site was used to estimated parameters of a simple model of Pu transport in agroecosystems. The parameter estimates for corn were compared to those previously obtained for wheat and soybeans. Despite some differences in parameter estimates among crops, the relative importances of atmospheric deposition, resuspension and root uptake were similar among crops. For even small deposition rates, the relative importances of processes for Pu contamination of corn grain should be: transfer of atmospheric deposition from vegetation surfaces to grain surfaces during combining > resuspension of soil to grain surfaces > root uptake. Approximately 3.9 x 10 -5 of a year's atmospheric deposition is transferred to grain. Approximately 6.2 x 10 -9 of the Pu inventory in the soil is resuspended to corn grain, and a further 7.3 x 10 -10 of the soil inventory is absorbed by roots and translocated to grains

  15. Trace organic compounds in wet atmospheric deposition: an overview

    Science.gov (United States)

    Steinheimer, T.R.; Johnson, S.M.

    1987-01-01

    An overview of the occurrence of organic compounds in wet atmospheric deposition is given. Multiplicity of sources and problems associated with source identification are discussed. Available literature is reviewed by using citations from Chemical Abstracts and Water Resources Abstracts through June 1985 and includes reports published through December 1984 that summarize current knowledge. Approaches to the chemical determination of organic compounds in precipitation are examined in addition to aspects of sampling protocols. Best methods for sample collection and preparation for instrumental analysis continue to be discussed among various investigators. Automatic wet-deposition-only devices for collection and extraction are preferred. Classes of organic compounds that have been identified in precipitation include a spectrum of compounds with differing properties of acidity or basicity, polarity, and water solubility. Those compounds that have been reported in rainfall, snowfall, and ice include hydrocarbons (both aromatic and nonaromatic), chlorinated derivatives of these hydrocarbons, carbonyl compounds (both acidic and nonacidic), and carboxylic acids and esters. Formic and acetic are the most abundant organic acids present. Cloudwater, fogwater, and mist also have been collected and analyzed for organic composition.

  16. Mercury emission to the atmosphere from municipal solid waste landfills: A brief review

    Science.gov (United States)

    Tao, Zhengkai; Dai, Shijin; Chai, Xiaoli

    2017-12-01

    Municipal solid waste (MSW) landfill is regarded as an important emission source of atmospheric mercury (Hg), which is associated with potential health and environmental risks, as outlined by the Minamata Convention on Hg. This review presents the current state of knowledge with regards to landfill Hg sources, Hg levels in MSW and cover soils, Hg emission to the atmosphere, available Hg biogeochemical transformations, research methods for Hg emission, and important areas for future research. In addition, strategies for controlling landfill Hg emissions are considered, including reducing the Hg load in landfill and in situ controls. These approaches mainly focus on Hg source reduction, Hg recycling programs, public education, and in situ technology such as timely soil cover, vegetation, and end-of-pipe technology for controlling Hg emission from landfill gas.

  17. Measurements of gaseous mercury exchanges at the sediment-water, water-atmosphere and sediment-atmosphere interfaces of a tidal environment (Arcachon Bay, France).

    Science.gov (United States)

    Bouchet, Sylvain; Tessier, Emmanuel; Monperrus, Mathilde; Bridou, Romain; Clavier, Jacques; Thouzeau, Gerard; Amouroux, David

    2011-05-01

    The elemental mercury evasion from non-impacted natural areas is of significant importance in the global Hg cycle due to their large spatial coverage. Intertidal areas represent a dynamic environment promoting the transformations of Hg species and their subsequent redistribution. A major challenge remains in providing reliable data on Hg species variability and fluxes under typical transient tidal conditions found in such environment. Field experiments were thus carried out to allow the assessment and comparison of the magnitude of the gaseous Hg fluxes at the three interfaces, sediment-water, sediment-atmosphere and water-atmosphere of a mesotidal temperate lagoon (Arcachon Bay, Aquitaine, France) over three distinct seasonal conditions. The fluxes between the sediment-water and the sediment-atmosphere interfaces were directly evaluated with field flux chambers, respectively static or dynamic. Water-atmosphere fluxes were evaluated from ambient concentrations using a gas exchange model. The fluxes at the sediment-water interface ranged from -5.0 to 5.1 ng m(-2) h(-1) and appeared mainly controlled by diffusion. The occurrence of macrophytic covers (i.e.Zostera noltii sp.) enhanced the fluxes under light radiations. The first direct measurements of sediment-atmosphere fluxes are reported here. The exchanges were more intense and variable than the two other interfaces, ranging between -78 and 40 ng m(-2) h(-1) and were mostly driven by the overlying atmospheric Hg concentrations and superficial sediment temperature. The exchanges between the water column and the atmosphere, computed as a function of wind speed and gaseous mercury saturation ranged from 0.4 to 14.5 ng m(-2) h(-1). The flux intensities recorded over the intertidal sediments periodically exposed to the atmosphere were roughly 2 to 3 times higher than the fluxes of the other interfaces. The evasion of elemental mercury from emerged intertidal sediments is probably a significant pathway for Hg evasion in

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

    Science.gov (United States)

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

    2017-09-15

    Mercury sulfides are used in Ayurvedic medicines, Tibetan medicines, and Chinese medicines for thousands of years and are still used today. Cinnabar (α-HgS) and metacinnabar (β-HgS) are different from mercury chloride (HgCl 2 ) and methylmercury (MeHg) in their disposition and toxicity. Whether such scenario applies to weanling and aged animals is not known. To address this question, weanling (21d) and aged (450d) rats were orally given Zuotai (54% β-HgS, 30mg/kg), HgS (α-HgS, 30mg/kg), HgCl 2 (34.6mg/kg), or MeHg (MeHgCl, 3.2mg/kg) for 7days. Accumulation of Hg in kidney and liver, and the toxicity-sensitive gene expressions were examined. Animal body weight gain was decreased by HgCl 2 and to a lesser extent by MeHg, but unaltered after Zuotai and HgS. HgCl 2 and MeHg produced dramatic tissue Hg accumulation, increased kidney (kim-1 and Ngal) and liver (Ho-1) injury-sensitive gene expressions, but such changes are absent or mild after Zuotai and HgS. Aged rats were more susceptible than weanling rats to Hg toxicity. To examine roles of transporters in Hg accumulation, transporter gene expressions were examined. The expression of renal uptake transporters Oat1, Oct2, and Oatp4c1 and hepatic Oatp2 was decreased, while the expression of renal efflux transporter Mrp2, Mrp4 and Mdr1b was increased following HgCl 2 and MeHg, but unaffected by Zuotai and HgS. Thus, Zuotai and HgS differ from HgCl 2 and MeHg in producing tissue Hg accumulation and toxicity, and aged rats are more susceptible than weanling rats. Transporter expression could be adaptive means to reduce tissue Hg burden. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Gradient measurements of gaseous elemental mercury (Hg0) in the marine boundary layer of the northwest Sea of Japan (East Sea).

    Science.gov (United States)

    Kalinchuk, Viktor; Lopatnikov, Evgeny; Astakhov, Anatoly

    2018-06-01

    Gaseous elemental mercury (Hg 0 ) is a prolific and persistent contaminant in the atmosphere. Atmospheric concentrations of Hg 0 were determined from 17 September to 7 October 2015 in the northwest Sea of Japan aboard the Russian research vessel Professor Gagarinsky. Simultaneous measurements of Hg 0 concentrations were performed 2 m and 20 m above the sea surface using automatic Hg 0 analysers RA-915M and RA-915+, respectively. Concentrations ranged from 0.3 to 25.9 ng/m 3 (n = 5207) and from 0.3 to 27.8 ng/m 3 (n = 4415), with medians of 1.7 and 1.6 ng/m 3 , respectively. Elevated Hg 0 was observed during three episodes from 19 to 22 September, likely caused by one or more of the following factors: 1) atmospheric transport of Hg 0 from the west and south-west (from N. Korea, China, and the Yellow Sea region); 2) Hg 0 emission from the sea due to pollution by water from the Tumannaya River; or 3) underwater geological activities. Increased Hg 0 concentration was observed during periods when air masses flowed from the south, and low concentrations were observed when air masses came from the north. A daytime increase of Hg 0 concentrations at a height of 2 m occurred simultaneously with decreasing Hg 0 at a height of 20 m. These diurnal variations suggest that two contrasting processes occur during the daytime in the marine boundary layer (MBL): Hg 0 emission from the sea surface and Hg 0 oxidation in the MBL by active halogens formed by photolysis. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Atmospheric Nitrogen Deposition at Two Sites in an Arid Environment of Central Asia.

    Science.gov (United States)

    Li, Kaihui; Liu, Xuejun; Song, Wei; Chang, Yunhua; Hu, Yukun; Tian, Changyan

    2013-01-01

    Arid areas play a significant role in the global nitrogen cycle. Dry and wet deposition of inorganic nitrogen (N) species were monitored at one urban (SDS) and one suburban (TFS) site at Urumqi in a semi-arid region of central Asia. Atmospheric concentrations of NH3, NO2, HNO3, particulate ammonium and nitrate (pNH4 (+) and pNO3 (-)) concentrations and NH4-N and NO3-N concentrations in precipitation showed large monthly variations and averaged 7.1, 26.6, 2.4, 6.6, 2.7 µg N m(-3) and 1.3, 1.0 mg N L(-1) at both SDS and TFS. Nitrogen dry deposition fluxes were 40.7 and 36.0 kg N ha(-1) yr(-1) while wet deposition of N fluxes were 6.0 and 8.8 kg N ha(-1) yr(-1) at SDS and TFS, respectively. Total N deposition averaged 45.8 kg N ha(-1) yr(-1)at both sites. Our results indicate that N dry deposition has been a major part of total N deposition (83.8% on average) in an arid region of central Asia. Such high N deposition implies heavy environmental pollution and an important nutrient resource in arid regions.

  1. Characterizations of wet mercury deposition to a remote islet (Pengjiayu) in the subtropical Northwest Pacific Ocean

    Science.gov (United States)

    Sheu, Guey-Rong; Lin, Neng-Huei

    2013-10-01

    Thirty-four weekly rainwater samples were collected in 2009 at Pengjiayu, a remote islet in the subtropical Northwest (NW) Pacific Ocean, to study the distribution of rainwater mercury (Hg) concentrations and associated wet deposition fluxes. This is the first study concerning wet Hg deposition to the subtropical NW Pacific Ocean downwind of the East Asian continent, which is the major source region for Hg emissions worldwide. Sample Hg concentrations ranged from 2.25 to 22.33 ng L-1, with a volume-weighted mean (VWM) concentration of 8.85 ng L-1. The annual wet Hg deposition flux was 10.18 μg m-2, about 2.5 times the fluxes measured at sites on the Pacific coast of the USA, supporting the hypothesis that deposition is higher in the western than in the eastern Pacific. Seasonal VWM concentrations were 7.23, 11.58, 7.82, and 9.84 ng L-1, whereas seasonal wet deposition fluxes were 2.14, 3.45, 2.38, and 2.21 μg m-2, for spring, summer, fall and winter, respectively. Higher summer wet Hg deposition was a function of both higher rainwater Hg concentration and greater rainfall. The seasonal pattern of rainwater Hg concentrations was the opposite of the general seasonal pattern of the East Asian air pollutant export. Since there is no significant anthropogenic Hg emission source on the islet of Pengjiayu, the observed high summertime rainwater Hg concentration hints at the importance of Hg0 oxidation and/or scavenging of upper-altitude reactive gaseous Hg (RGM) by deep convection. Direct anthropogenic RGM emissions from the East Asian continent may not contribute significantly to the rainwater Hg concentrations, but anthropogenic Hg0 emissions could be transported to the upper troposphere or marine boundary layer (MBL) where they can be oxidized to produce RGM, which will then be effectively scavenged by cloud water and rainwater.

  2. Atmospheric nitrogen deposition influences denitrification and nitrous oxide production in lakes.

    Science.gov (United States)

    McCrackin, Michelle L; Elser, James J

    2010-02-01

    Microbially mediated denitrification is an important process that may ameliorate the effects of nitrogen (N) loading by permanently removing excess N inputs. In this study, we measured the rate of denitrification and nitrous oxide (N2O) production during denitrification in sediments from 32 Norwegian lakes at the high and low ends of a gradient of atmospheric N deposition. Denitrification and N2O production rates averaged 41.7 and 1.1 micromol N x m(-2) x h(-1), respectively, for high-deposition lakes. There was no detectable denitrification or N2O production in low-deposition lakes. Epilimnetic nitrate concentration was strongly correlated with denitrification rate (r2 = 0.67). We also measured the denitrification rate in response to experimental additions of organic carbon, nitrate, and phosphorus. Experimental nitrate additions stimulated denitrification in sediments of all lakes, regardless of N deposition level. In fact, the rate of denitrification in nitrate-amended treatments was the same magnitude for lakes in both deposition areas. These findings suggest that lake sediments possess considerable capacity to remove nitrate and that this capacity has not been saturated under conditions of chronic N loading. Further, nitrous oxide was nearly 3% of the total gaseous product during denitrification in high-deposition lakes, a fraction that is comparable to polluted marine sediments. Our findings suggest that, while lakes play an important role in N removal in the landscape, they may be a source of N2O emissions, especially in areas subject to elevated N inputs.

  3. Interactions between atmospheric circulation, nutrient deposition, and tropical forest primary production (Invited)

    Science.gov (United States)

    Randerson, J. T.; Chen, Y.; Rogers, B. M.; Morton, D. C.; van der Werf, G.; Mahowald, N. M.

    2010-12-01

    Tropical forests influence regional and global climate by means of several pathways, including by modifying surface energy exchange and by forming clouds. High levels of precipitation, leaching, and soil weathering limit nutrient availability in these ecosystems. Phosphorus (P) is a key element limiting net primary production, and in some areas, including forests recovering from prior disturbance, nitrogen (N) also may limit some components of production. Here we quantified atmospheric P and N inputs to these forests from fires using satellite-derived estimates of emissions and atmospheric models. In Africa and South America, cross-biome transport of fire-emitted aerosols and reactive N gases from savannas and areas near the deforestation frontier increased deposition of P and N in interior forests. Equatorward atmospheric transport during the dry (fire) season in one hemisphere was linked with surface winds moving toward the inter-tropical convergence zone (ITCZ) in the other hemisphere. Deposition levels were higher in tropical forests in Africa than in South America because of large savanna areas with high levels of fire emissions in both southern and northern Africa. We conclude by describing a potential feedback loop by which equatorward transport of fire emissions, dust, and spores sustains the productivity of tropical forests. We specifically assessed evidence that savanna-to-forest atmospheric transport of nutrients increases forest productivity, height, and rates of evapotranspiration (ET). In parallel, we examined the degree to which increases in ET and surface roughness in tropical forests have the potential to strengthen several components of the Hadley circulation, including deep convection, equatorward return flow (near the surface), and the intensity of seasonal drought in the subtropics (thereby increasing fires). These interactions are important for understanding biogeochemical - climate interactions on millennial timescales and for quantifying how

  4. 199Hg Moessbauer measurements on mercury, alloys and Hg-fluorides

    International Nuclear Information System (INIS)

    Wurtinger, W.; Kankeleit, E.

    1979-01-01

    The Moessbauer effect on the 158 keV 5/2 - -1/2 - transition in 199 Hg, of the order of 10 ppm, has been studied using the current integration technique. The isomer shift between the Hg(I)- and Hg(II)-fluorides as well as the quadrupole splitting in Hg 2 Pt and Hg 2 F 2 are interpreted in terms of relativistic Hartree-Fock-Slater and Molecular Orbital calculations. The following nuclear parameters could be derived: Δ[r 2 ] = (3.2+-1.1) 10 -3 fm 2 and Q(5/2 - ) = (-0.8+-0.4)b. Evidence for an oblate triaxially deformed 199 Hg nucleus is derived from particle plus rotor calculations. (orig.)

  5. Current state and temporal evolution of the chemical composition of atmospheric depositions in forest areas of the CONECOFOR network

    Directory of Open Access Journals (Sweden)

    Marchetto A

    2014-04-01

    Full Text Available Current state and temporal evolution of the chemical composition of atmospheric depositions in forest areas of the CONECOFOR network. Since 1997, atmospheric deposition was sampled and analyzed in the permanent plots of the Italian network for the evaluation of forest health (CONECOFOR, under the coordination of the Italian Forest Service. This paper presents the results of the activity carried out in 2009, when the EU-funded LIFE+ “FutMon” project allowed to extend the sampling network to 22 sites. Long-term trends will also be evaluated for the sampling sites with the longest time series. The sampling of open field bulk deposition was performed in a clearance close to the CONECOFOR permanent plots, while throughfall deposition and stemflow (in beech stand, only were sampled in the plot. Deposition samples were collected weekly and sent to the laboratories, where they were analyzed for pH, conductivity, major ions, and total carbon and nitrogen. Most measured variables showed a strong geographical gradient. For example, nitrogen deposition was relatively high in the Po plain (where the emissions of nitrogen oxides and ammonia are the highest and surrounding hills, reaching 10-20 kgN ha-1 y-1 in the open field and 13-25 kgN ha-1 y-1 in the throughfall. Sulphate deposition also showed a marked geographical gradient. Deposition of marine aerosol also had an important impact on the chemical composition of atmospheric deposition in Italy, together with the episodic deposition of Saharan dust, which showed a marked gradient, with highest values in the southernmost plots. Trend analysis was carried out on 10 sites running since the beginning of the program. A general negative trend in sulphate concentration was detected, paralleled in most plots by a positive trend in deposition pH, in good agreement with the strong reduction in the emission of sulphur dioxide recorded in the last decades. Nitrogen concentration also showed a significant decrease

  6. Neutrons and gamma transport in atmosphere by Tripoli-2 code. Energy deposit and electron current time function

    International Nuclear Information System (INIS)

    Vergnaud, T.; Nimal, J.C.; Ulpat, J.P.; Faucheux, G.

    1988-01-01

    The Tripoli-2 computer code has been adapted to calculate, in addition to energy deposit in matter by neutrons (Kerma) the energy deposit by gamma produced in neutronic impacts and the induced recoil electron current. The energy deposit conduces at air ionization, consequently at a conductibility. This knowledge added at that of electron current permit to resolve the Maxwell equations of electromagnetic field. The study is realized for an atmospheric explosion 100 meters high. The calculations of energy deposit and electron current have been conducted as far as 2.5km [fr

  7. Mercury Sources and Cycling in the Great Lakes: Dramatic Changes Resulting from Altered Atmospheric Loads and the Near-Shore Shunt

    Science.gov (United States)

    Krabbenhoft, D. P.; DeWild, J. F.; Maglio, M. M.; Tate, M. T.; Ogorek, J. M.; Hurley, J. P.; Lepak, R.

    2013-12-01

    Mercury (Hg) contamination of the aquatic food webs across the Great Lakes remains a significant environmental issue. However, our ability to prescribe corrective actions has been significantly hampered by a scarcity of data, particularly for methylmercury (MeHg) the most toxic and bioaccumulative form of mercury in freshwater ecosystems. As part of the Great Lakes Restoration Initiative initiated in 2010, a joint effort was undertaken by the U.S. Geological Survey (USGS) and U.S. Environmental Protection Agency (USEPA) to improve our understanding of total Hg and MeHg concentrations and distributions in the Great Lakes. Since 2010, sampling surveys have been conducted at about 15-20 stations twice annually (April and August) at 15-20 stations per lake to collect data from both cold and warm water conditions. All sampling was conducted using trace-metal free protocols using a sampling rosette equipped with 12 Teflon-lined Niskin. Water samples were collected at predetermined depths: mid-epilimnion, mid-thermocline, deep chlorophyll layer, mid-hypolimnion, and about 2 meters above the bottom. Seston samples were collected from the top 20 meters using plankton nets, while bottom sediments and benthos samples were acquired using a ponar sampler. Water, biota, and sediment samples were all analyzed for Hg and MeHg concentration at the USGS Mercury Research Laboratory in Middleton, Wisconsin. Several important trends are apparent from the water column samples. First, most stations reveal a strong top-to-bottom declining trend total Hg concentration, underscoring the importance of atmospheric deposition to the Great Lakes. Methylmercury profiles, show maximal concentrations at the thermocline or deep chlorophyll layer, suggesting in situ water-column MeHg production. Calculations suggest this in-lake MeHg source is similar in magnitude to tributary loading of MeHg, which heretofore was thought to be the dominant MeHg source. Aqueous total Hg results also suggest that

  8. Atmospheric behavior, deposition, and budget of radioactive materials from the Fukushima Daiichi nuclear power plant in March 2011

    Science.gov (United States)

    Morino, Y.; Ohara, T.; Nishizawa, M.

    2011-12-01

    To understand the atmospheric behavior of radioactive materials emitted from the Fukushima Daiichi nuclear power plant after the nuclear accident that accompanied the great Tohoku earthquake and tsunami on 11 March 2011, we simulated the transport and deposition of iodine-131 and cesium-137 using a chemical transport model. The model roughly reproduced the observed temporal and spatial variations of deposition rates over 15 Japanese prefectures (60-400 km from the plant), including Tokyo, although there were some discrepancies between the simulated and observed rates. These discrepancies were likely due to uncertainties in the simulation of emission, transport, and deposition processes in the model. A budget analysis indicated that approximately 13% of iodine-131 and 22% of cesium-137 were deposited over land in Japan, and the rest was deposited over the ocean or transported out of the model domain (700 × 700 km2). Radioactivity budgets are sensitive to temporal emission patterns. Accurate estimation of emissions to the air is important for estimation of the atmospheric behavior of radionuclides and their subsequent behavior in land water, soil, vegetation, and the ocean.

  9. Methylmercury declines in a boreal peatland when experimental sulfate deposition decreases

    Science.gov (United States)

    Jill K. Coleman Wasik; Carl P.J. Mitchell; Daniel R. Engstrom; Edward B. Swain; Bruce A. Monson; Steven J. Balogh; Jeffrey D. Jeremiason; Brian A. Branfireun; Susan L. Eggert; Randall K. Kolka; James E. Almendinger

    2012-01-01

    Between 2001 and 2008 we experimentally manipulated atmospheric sulfate-loading to a small boreal peatland and monitored the resulting short and long-term changes in methylmercury (MeHg) production. MeHg concentrations and %MeHg (fraction of total-Hg (HgT) present as MeHg) in the porewaters of the experimental treatment reached peak values within...

  10. Sources of mercury in sediments, water, and fish of the lakes of Whatcom County, Washington

    Science.gov (United States)

    Paulson, Anthony J.

    2004-01-01

    Concerns about mercury (Hg) contamination in Lake Whatcom, Washington, were raised in the late 1990s after a watershed protection survey reported elevated concentrations of Hg in smallmouth bass. The U.S. Geological Survey, the Whatcom County Health Department, and the Washington State Department of Ecology (Ecology) cooperated to develop a study to review existing data and collect new data that would lead to a better understanding of Hg deposition to Lake Whatcom and other lakes in Whatcom County, Washington. A simple atmospheric deposition model was developed that allowed comparisons of the deposition of Hg to the surfaces of each lake. Estimates of Hg deposition derived from the model indicated that the most significant deposition of Hg would have occurred to the lakes north of the City of Bellingham. These lakes were in the primary wind pattern of two municipal waste incinerators. Of all the lakes examined, basin 1 of Lake Whatcom would have been most affected by the Hg emissions from the chlor-alkali plant and the municipal sewage-sludge incinerator in the City of Bellingham. The length-adjusted concentrations of Hg in largemouth and smallmouth bass were not related to estimated deposition rates of Hg to the lakes from local atmospheric sources. Total Hg concentrations in the surface sediments of Lake Whatcom are affected by the sedimentation of fine-grained particles, whereas organic carbon regulates the concentration of methyl-Hg in the surface sediments of the lake. Hg concentrations in dated sediment core samples indicate that increases in Hg sedimentation were largest during the first half of the 20th century. Increases in Hg sedimentation were smaller after the chlor-alkali plant and the incinerators began operating between 1964 and 1984. Analysis of sediments recently deposited in basin 1 of Lake Whatcom, Lake Terrell, and Lake Samish indicates a decrease in Hg sedimentation. Concentrations of Hg in Seattle precipitation and in tributary waters were

  11. Diamond synthesis at atmospheric pressure by microwave capillary plasma chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Hemawan, Kadek W.; Gou, Huiyang; Hemley, Russell J. [Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Rd., NW, Washington, DC 20015 (United States)

    2015-11-02

    Polycrystalline diamond has been synthesized on silicon substrates at atmospheric pressure, using a microwave capillary plasma chemical vapor deposition technique. The CH{sub 4}/Ar plasma was generated inside of quartz capillary tubes using 2.45 GHz microwave excitation without adding H{sub 2} into the deposition gas chemistry. Electronically excited species of CN, C{sub 2}, Ar, N{sub 2}, CH, H{sub β}, and H{sub α} were observed in the emission spectra. Raman measurements of deposited material indicate the formation of well-crystallized diamond, as evidenced by the sharp T{sub 2g} phonon at 1333 cm{sup −1} peak relative to the Raman features of graphitic carbon. Field emission scanning electron microscopy images reveal that, depending on the growth conditions, the carbon microstructures of grown films exhibit “coral” and “cauliflower-like” morphologies or well-facetted diamond crystals with grain sizes ranging from 100 nm to 10 μm.

  12. Atmospheric deposition having been one of the major source of Pb in Jiaozhou Bay

    Science.gov (United States)

    Yang, Dongfang; Miao, Zhenqing; Zhang, Xiaolong; Wang, Qi; Li, Haixia

    2018-03-01

    Many marine bays have been polluted by Pb due to the rapid development of industry, and identifying the major source of Pb is essential to pollution control. This paper analyzed the distribution and pollution source of Pb in Jiaozhou Bay in 1988. Results showed that Pb contents in surface waters in Jiaozhou Bay in April, July and October 1988 were 5.52-24.61 μg L‑1, 7.66-38.62 μg L‑1 and 6.89-19.30 μg L‑1, respectively. The major Pb sources in this bay were atmospheric deposition, and marine current, whose source strengths were 19.30-24.61μg L‑1 and 38.62 μg L‑1, respectively. Atmospheric deposition had been one of the major Pb sources in Jiaozhou Bay, and the source strengths were stable and strong. The pollution level of Pb in this bay in 1988 was moderate to heavy, and the source control measurements were necessary.

  13. Depletion of atmospheric gaseous elemental mercury by plant uptake at Mt. Changbai, Northeast China

    Directory of Open Access Journals (Sweden)

    X. Fu

    2016-10-01

    Full Text Available There exists observational evidence that gaseous elemental mercury (GEM can be readily removed from the atmosphere via chemical oxidation followed by deposition in the polar and sub-polar regions, free troposphere, lower stratosphere, and marine boundary layer under specific environmental conditions. Here we report GEM depletions in a temperate mixed forest at Mt. Changbai, Northeast China. The strong depletions occurred predominantly at night during the leaf-growing season and in the absence of gaseous oxidized mercury (GOM enrichment (GOM  <  3 pg m−3. Vertical gradients of decreasing GEM concentrations from layers above to under forest canopy suggest in situ loss of GEM to forest canopy at Mt. Changbai. Foliar GEM flux measurements showed that the foliage of two predominant tree species is a net sink of GEM at night, with a mean flux of −1.8 ± 0.3 ng m2 h−1 over Fraxinus mandshurica (deciduous tree species and −0.1 ± 0.2 ng m2 h−1 over Pinus Koraiensis (evergreen tree species. Daily integrated GEM δ202Hg, Δ199Hg, and Δ200Hg at Mt. Changbai during 8–18 July 2013 ranged from −0.34 to 0.91 ‰, from −0.11 to −0.04 ‰ and from −0.06 to 0.01 ‰, respectively. A large positive shift in GEM δ202Hg occurred during the strong GEM depletion events, whereas Δ199Hg and Δ200Hg remained essentially unchanged. The observational findings and box model results show that uptake of GEM by forest canopy plays a predominant role in the GEM depletion at Mt. Changbai forest. Such depletion events of GEM are likely to be a widespread phenomenon, suggesting that the forest ecosystem represents one of the largest sinks ( ∼ 1930 Mg of atmospheric Hg on a global scale.

  14. Mercury Stable Isotopes Discriminate Different Populations of European Seabass and Trace Potential Hg Sources around Europe.

    Science.gov (United States)

    Cransveld, Alice; Amouroux, David; Tessier, Emmanuel; Koutrakis, Emmanuil; Ozturk, Ayaka A; Bettoso, Nicola; Mieiro, Cláudia L; Bérail, Sylvain; Barre, Julien P G; Sturaro, Nicolas; Schnitzler, Joseph; Das, Krishna

    2017-11-07

    Our study reports the first data on mercury (Hg) isotope composition in marine European fish, for seven distinct populations of the European seabass, Dicentrarchus labrax. The use of δ 202 Hg and Δ 199 Hg values in SIBER enabled us to estimate Hg isotopic niches, successfully discriminating several populations. Recursive-partitioning analyses demonstrated the relevance of Hg stable isotopes as discriminating tools. Hg isotopic values also provided insight on Hg contamination sources for biota in coastal environment. The overall narrow range of δ 202 Hg around Europe was suggested to be related to a global atmospheric contamination while δ 202 Hg at some sites was linked either to background contamination, or with local contamination sources. Δ 199 Hg was related to Hg levels of fish but we also suggest a relation with ecological conditions. Throughout this study, results from the Black Sea population stood out, displaying a Hg cycling similar to fresh water lakes. Our findings bring out the possibility to use Hg isotopes in order to discriminate distinct populations, to explore the Hg cycle on a large scale (Europe) and to distinguish sites contaminated by global versus local Hg source. The interest of using Hg sable isotopes to investigate the whole European Hg cycle is clearly highlighted.

  15. Tracing the fate of atmospheric nitrate deposited onto a forest ecosystem in Eastern Asia using Δ17O

    Directory of Open Access Journals (Sweden)

    I. Noguchi

    2010-02-01

    Full Text Available The stable isotopic compositions of nitrate in precipitation (wet deposition and groundwater (spring, lake, and stream water were determined for the island of Rishiri, Japan, so as to use the 17O anomalies (Δ17O to trace the fate of atmospheric nitrate that had deposited onto the island ecosystem, which is a representative background forest ecosystem for eastern Asia. The deposited nitrate had large 17O anomalies with Δ17O values ranging from +20.8‰ to +34.5‰ (n = 32 with +26.2‰ being the annual average. The maximum Δ17O value of +34.5‰, obtained for precipitation on the 23rd to 24th of February 2007, was an extraordinarily large value among values for all samples of precipitation in Rishiri. Most nitrate in the sample might have been produced via NO3 radical in a highly polluted air mass that had been supplied from megacities on the eastern coast of the Asian continent. On the other hand, nitrate in groundwater had small Δ17O values ranging from +0.9‰ to 3.2‰ (n = 19, which corresponds to an mixing ratio of atmospheric nitrate to total nitrate of (7.4±2.6%. Comparing the inflow and outflow of atmospheric nitrate in groundwater within the island, we estimated that the direct drainage accounts for (8.8±4.6% of atmospheric nitrate that has deposited on the island and that the residual portion has undergone biological processing before being exported from the forest ecosystem.

  16. NKS NordRisk II: Atlas of long-range atmospheric dispersion and deposition of radionuclides from selected risk sites in the Northern Hemisphere

    International Nuclear Information System (INIS)

    Smith Korsholm, U.; Havskov Soerensen, J.; Astrup, P.; Lauritzen, B.

    2011-04-01

    The present atlas has been developed within the NKS/NordRisk-II project 'Nuclear risk from atmospheric dispersion in Northern Europe'. The atlas describes risks from hypothetical long-range dispersion and deposition of radionuclides from 16 nuclear risk sites on the Northern Hemisphere. The atmospheric dispersion model calculations cover a period of 30 days following each release to ensure almost complete deposition of the dispersed material. The atlas contains maps showing the total deposition and time-integrated air concentration of Cs-137 and I-131 based on three years of meteorological data spanning the climate variability associated with the North Atlantic Oscillation, and corresponding time evolution of the ensemble mean atmospheric dispersion. (Author)

  17. NKS NordRisk II: Atlas of long-range atmospheric dispersion and deposition of radionuclides from selected risk sites in the Northern Hemisphere

    Energy Technology Data Exchange (ETDEWEB)

    Smith Korsholm, U.; Havskov Soerensen, J. (Danish Meteorological Institute (DMI), Copenhagen (Denmark)); Astrup, P.; Lauritzen, B. (Technical Univ. of Denmark, Risoe National Lab. for Sustainable Energy. Radiation Research Div., Roskilde (Denmark))

    2011-04-15

    The present atlas has been developed within the NKS/NordRisk-II project 'Nuclear risk from atmospheric dispersion in Northern Europe'. The atlas describes risks from hypothetical long-range dispersion and deposition of radionuclides from 16 nuclear risk sites on the Northern Hemisphere. The atmospheric dispersion model calculations cover a period of 30 days following each release to ensure almost complete deposition of the dispersed material. The atlas contains maps showing the total deposition and time-integrated air concentration of Cs-137 and I-131 based on three years of meteorological data spanning the climate variability associated with the North Atlantic Oscillation, and corresponding time evolution of the ensemble mean atmospheric dispersion. (Author)

  18. Atmospheric organic nitrogen deposition: analysis of nationwide data and a case study in Northeast China.

    Science.gov (United States)

    Jiang, C M; Yu, W T; Ma, Q; Xu, Y G; Zou, H; Zhang, S C; Sheng, W P

    2013-11-01

    The origin of atmospheric dissolved organic nitrogen (DON) deposition is not very clear at present. Across China, the DON deposition was substantially larger than that of world and Europe, and we found significant positive correlation between contribution of DON and the deposition flux with pristine site data lying in outlier, possibly reflecting the acute air quality problems in China. For a case study in Northeast China, we revealed the deposited DON was mainly derived from intensive agricultural activities rather than the natural sources by analyzing the compiled dataset across China and correlating DON flux with NH4(+)-N and NO3(-)-N. Crop pollens and combustion of fossil fuels for heating probably contributed to summer and autumn DON flux respectively. Overall, in Northeast China, DON deposition could exert important roles in agro-ecosystem nutrient management and carbon sequestration of natural ecosystems; nationally, it was suggested to found rational network for monitoring DON deposition. Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.

  19. Development of atmospheric acid deposition in China from the 1990s to the 2010s

    International Nuclear Information System (INIS)

    Yu, Haili; He, Nianpeng; Wang, Qiufeng; Zhu, Jianxing; Gao, Yang; Zhang, Yunhai; Jia, Yanlong; Yu, Guirui

    2017-01-01

    Atmospheric acid deposition is a global environmental issue. China has been experiencing serious acid deposition, which is anticipated to become more severe with the country's economic development and increasing consumption of fossil fuels in recent decades. We explored the spatiotemporal variations of acid deposition (wet acid deposition) and its influencing factors by collecting nationwide data on pH and concentrations of sulfate (SO 4 2− ) and nitrate (NO 3 − ) in precipitation between 1980 and 2014 in China. Our results showed that average precipitation pH values were 4.59 and 4.70 in the 1990s and 2010s, respectively, suggesting that precipitation acid deposition in China has not seriously worsened. Average SO 4 2− deposition declined from 40.54 to 34.87 kg S ha −1 yr −1 but average NO 3 − deposition increased from 4.44 to 7.73 kg N ha −1 yr −1 . Specifically, the area of severe precipitation acid deposition in southern China has shrunk to some extent as a result of controlling the pollutant emissions; but the area of moderate precipitation acid deposition has expanded in northern China, associated with rapid industrial and transportation development. Furthermore, we found significant positive correlations between precipitation acid deposition, energy consumption, and rainfall. Our findings provide a relatively comprehensive evaluation of the spatiotemporal dynamics of precipitation acid deposition in China over past three decades, and confirm the idea that strategies implemented to save energy and control pollutant emissions in China have been effective in alleviating precipitation acid deposition. These findings might be used to demonstrate how developing countries could achieve economic development and environmental protection through the implementation of advanced technologies to reduce pollutant emissions. - Highlights: • Explore spatial and temporal dynamics of wet acid deposition during three decades in China. • Acid

  20. Depositional characteristics of atmospheric polybrominated diphenyl ethers on tree barks.

    Science.gov (United States)

    Chun, Man Young

    2014-07-17

    This study was conducted to determine the depositional characteristics of several tree barks, including Ginkgo (Ginkgo biloba), Pine (Pinus densiflora), Platanus (Platanus), and Metasequoia (Metasequoia glyptostroboides). These were used as passive air sampler (PAS) of atmospheric polybrominated diphenyl ethers (PBDEs). Tree barks were sampled from the same site. PBDEs were analyzed by highresolution gas chromatography/high-resolution mass spectrometer, and the lipid content was measured using the gravimetric method by n-hexane extraction. Gingko contained the highest lipid content (7.82 mg/g dry), whereas pine (4.85 mg/g dry), Platanus (3.61 mg/g dry), and Metasequoia (0.97 mg/g dry) had relatively lower content. The highest total PBDEs concentration was observed in Metasequoia (83,159.0 pg/g dry), followed by Ginkgo (53,538.4 pg/g dry), Pine (20,266.4 pg/g dry), and Platanus (12,572.0 pg/g dry). There were poor correlations between lipid content and total PBDE concentrations in tree barks (R(2)=0.1011, p =0.682). Among the PBDE congeners, BDE 206, 207 and 209 were highly brominated PBDEs that are sorbed to particulates in ambient air, which accounted for 90.5% (84.3-95.6%) of the concentration and were therefore identified as the main PBDE congener. The concentrations of particulate PBDEs deposited on tree barks were dependent on morphological characteristics such as surface area or roughness of barks. Therefore, when using the tree barks as the PAS of the atmospheric PBDEs, samples belonging to same tree species should be collected to reduce errors and to obtain reliable data.

  1. Simulation of trace metals and PAH atmospheric pollution over Greater Paris: Concentrations and deposition on urban surfaces

    Science.gov (United States)

    Thouron, L.; Seigneur, C.; Kim, Y.; Legorgeu, C.; Roustan, Y.; Bruge, B.

    2017-10-01

    Urban areas can be subject not only to poor air quality, but also to contamination of other environmental media by air pollutants. Here, we address the potential transfer of selected air pollutants (two metals and three PAH) to urban surfaces. To that end, we simulate meteorology and air pollution from Europe to a Paris suburban neighborhood, using a four-level one-way nesting approach. The meteorological and air quality simulations use urban canopy sub-models in order to better represent the effect of the urban morphology on the air flow, atmospheric dispersion, and deposition of air pollutants to urban surfaces. This modeling approach allows us to distinguish air pollutant deposition among various urban surfaces (roofs, roads, and walls). Meteorological model performance is satisfactory, showing improved results compared to earlier simulations, although precipitation amounts are underestimated. Concentration simulation results are also satisfactory for both metals, with a fractional bias Paris region. The model simulation results suggest that both wet and dry deposition processes need to be considered when estimating the transfer of air pollutants to other environmental media. Dry deposition fluxes to various urban surfaces are mostly uniform for PAH, which are entirely present in fine particles. However, there is significantly less wall deposition compared to deposition to roofs and roads for trace metals, due to their coarse fraction. Meteorology, particle size distribution, and urban morphology are all important factors affecting air pollutant deposition. Future work should focus on the collection of data suitable to evaluate the performance of atmospheric models for both wet and dry deposition with fine spatial resolution.

  2. Optical characterization of a-Si:H thin films grown by Hg-Photo-CVD

    International Nuclear Information System (INIS)

    Barhdadi, A.; Karbal, S.; M'Gafad, N.; Benmakhlouf, A.; Chafik El Idrissi, M.; Aka, B.M.

    2006-08-01

    Mercury-Sensitized Photo-Assisted Chemical Vapor Deposition (Hg-Photo-CVD) technique opens new possibilities for reducing thin film growth temperature and producing novel semiconductor materials suitable for the future generation of high efficiency thin film solar cells onto low cost flexible plastic substrates. This paper provides some experimental data resulting from the optical characterization of hydrogenated amorphous silicon thin films grown by this deposition technique. Experiments have been performed on both as-deposited layers and thermal annealed ones. (author) [fr

  3. Studies of the 198Hg(d,d') and 198Hg(d,p) reactions

    Science.gov (United States)

    Diaz Varela, Alejandra; Garrett, P. E.; Rand, E. T.; Ball, G. C.; Bilstein, V.; Laffoley, A. T.; Maclean, A. D.; Svensson, C. E.; Faestermann, T.; Hertenberger, R.; Wirth, H.-F.

    2017-09-01

    Limits on the electric dipole moment (EDM) continue to decrease for 199Hg, the most stringent upper limit for a nuclear EDM to date. The experimental limit on the observed atomic EDM for 199Hg is converted to a limit on the nuclear EDM via a calculation of the Schiff moment, requiring knowledge of the nuclear structure of 199Hg. The E 3 and E 1 strength distributions to the ground state of 199Hg, and E 2 transitions amongst excited states, would be ideal information to further constrain 199Hg Schiff moment theoretical models. The high level density of 199Hg makes those determinations challenging, however the similar information can be obtained from exploring surrounding even-even Hg isotopes. As part of a campaign to study the Hg isotopes near 199Hg, two experiments, 198Hg(d,d') 198Hg and 198Hg(d,p)199Hg reaction were performed using the Q3D spectrograph at the Maier-Leibnitz Laboratory (MLL) at Garching, Germany. A 22 MeV deuterium beam was used to impinge a 198Hg32S target. The (d,d') reaction allows us to probe the desired E 2 and E 3 matrix elements, while the (d,p) reaction provides information on the neutron single-particle states of 199Hg.

  4. Critical loads of nitrogen deposition and critical levels of atmospheric ammonia for semi-natural Mediterranean evergreen woodlands

    Directory of Open Access Journals (Sweden)

    P. Pinho

    2012-03-01

    Full Text Available Nitrogen (N has emerged in recent years as a key factor associated with global changes, with impacts on biodiversity, ecosystems functioning and human health. In order to ameliorate the effects of excessive N, safety thresholds such as critical loads (deposition fluxes and levels (concentrations can be established. Few studies have assessed these thresholds for semi-natural Mediterranean ecosystems. Our objective was therefore to determine the critical loads of N deposition and long-term critical levels of atmospheric ammonia for semi-natural Mediterranean evergreen woodlands. We have considered changes in epiphytic lichen communities, one of the most sensitive comunity indicators of excessive N in the atmosphere. Based on a classification of lichen species according to their tolerance to N we grouped species into response functional groups, which we used as a tool to determine the critical loads and levels. This was done for a Mediterranean climate in evergreen cork-oak woodlands, based on the relation between lichen functional diversity and modelled N deposition for critical loads and measured annual atmospheric ammonia concentrations for critical levels, evaluated downwind from a reduced N source (a cattle barn. Modelling the highly significant relationship between lichen functional groups and annual atmospheric ammonia concentration showed the critical level to be below 1.9 μg m−3, in agreement with recent studies for other ecosystems. Modelling the highly significant relationship between lichen functional groups and N deposition showed that the critical load was lower than 26 kg (N ha−1 yr−1, which is within the upper range established for other semi-natural ecosystems. Taking into account the high sensitivity of lichen communities to excessive N, these values should aid development of policies to protect Mediterranean woodlands from the initial effects of excessive N.

  5. Enhancing atmospheric mercury research in China to improve the current understanding of the global mercury cycle: the need for urgent and closely coordinated efforts.

    Science.gov (United States)

    Ci, Zhijia; Zhang, Xiaoshan; Wang, Zhangwei

    2012-06-05

    The current understanding of the global mercury (Hg) cycle remains uncertain because Hg behavior in the environment is very complicated. The special property of Hg causes the atmosphere to be the most important medium for worldwide dispersion and transformation. The source and fate of atmospheric Hg and its interaction with the surface environment are the essential topics in the global Hg cycle. Recent declining measurement trends of Hg in the atmosphere are in apparent conflict with the increasing trends in global anthropogenic Hg emissions. As the single largest country contributor of anthropogenic Hg emission, China's role in the global Hg cycle will become more and more important in the context of the decreasing man-made Hg emission from developed regions. However, much less Hg information in China is available. As a global pollutant which undergoes long-range transport and is persistence in the environment, increasing Hg knowledge in China could not only promote the Hg regulation in this country but also improve the understanding of the fundamental of the global Hg cycle and further push the abatement of this toxin on a global scale. Then the atmospheric Hg research in China may be a breakthrough for improving the current understanding of the global Hg cycle. However, due to the complex behavior of Hg in the atmosphere, a deeper understanding of the atmospheric Hg cycle in China needs greater cooperation across fields.

  6. History of HgTe-based photodetectors in Poland

    Science.gov (United States)

    Rogalski, A.

    2010-09-01

    In Poland, the HgCdTe studies began in 1960 at the Institute of Physics, Warsaw University. The material processing laboratory was created by Giriat and later by Dziuba, Gałązka, and others. Bridgman technique with sealed thick wall quartz ampoules was used to grow material suitable for research and experimental devices. Among the first papers published in 1961 and 1963 there were the Polish works devoted to preparation, doping, and electrical properties of HgCdTe. Infrared detector's research and development efforts in Poland were concentrated mostly on uncooled market niche. At the beginning, a modified isothermal vapour phase epitaxy has been used for research and commercial fabrication of photoconductive, photoelectromagnetic and other HgCdTe devices. Bulk growth and liquid phase epitaxy were also used. Recently, the fabrication of infrared devices relies on low temperature epitaxial technique, namely metalorganic vapour phase deposition. At present stage of development, the photoconductive and photoelectromagnetic (PEM) detectors are gradually replaced with photovoltaic devices which offer inherent advantages of no electric or magnetic bias, no heat load and no flicker noise. Potentially, photodiodes offer high performance and very fast response. However, conventional photovoltaic uncooled detectors suffer from low quantum efficiency and very low junction resistance. The problems have been solved with advanced band gap engineered architecture, multiple cell heterojunction devices connected in series, and monolithic integration of the detectors with microoptics. In final part of the paper, the Polish achievements in technology and performance of HgMnTe and HgZnTe photodetectors are presented.

  7. 46 CFR 53.12-1 - General (modifies HG-600 through HG-640).

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false General (modifies HG-600 through HG-640). 53.12-1... HEATING BOILERS Instruments, Fittings, and Controls (Article 6) § 53.12-1 General (modifies HG-600 through HG-640). (a) The instruments, fittings and controls for heating boilers shall be as indicated in HG...

  8. Mercury distribution in the foliage and soil profiles of the Tibetan forest: Processes and implications for regional cycling

    International Nuclear Information System (INIS)

    Gong, Ping; Wang, Xiao-ping; Xue, Yong-gang; Xu, Bai-qing; Yao, Tan-dong

    2014-01-01

    Remote forests are considered a pool of Mercury (Hg) in the global Hg cycle. However, notably few studies have investigated the fate of Hg in the Tibetan forest. In this study, fifty-two foliage samples and seven litter/soil profiles were collected throughout the Tibetan forest. The concentrations of total Hg (THg) in foliage were positively correlated with longitude and negatively correlated with altitude, indicating that the emission of Hg is expected to decrease with increasing distance from emission sources to the Tibetan forest. The deposition flux of THg in the Tibetan forest (with an air-to-forest ground flux of 9.2 μg/m 2 /year) is ∼2 times the flux in clearings, which is suggestive of enhanced Hg deposition by the forest. The depositional Hg is eventually stored in the forest soil, and the soil acts as a net ‘sink’ for Hg. - Highlights: • Foliage can be used as bio-indicator for monitoring the spatial Hg distribution. • The Tibetan forest can enhance the atmospheric Hg deposition to the ground. • The Tibetan forest soil is a pool of Hg that acts to delay the regional cycling of Hg. - The Tibetan forest can accumulate atmospheric Hg, which undergoes long-range transport, and the soil of Tibetan forest acts as the final Hg ‘sink’

  9. Deposition of radionuclides and their subsequent relocation in the environment following an accidental release to the atmosphere

    International Nuclear Information System (INIS)

    Underwood, B.Y.; Roed, J.; Paretzke, H.G.

    1993-01-01

    The objective of the project is to improve, as necessary, the models and parameterizations used in estimating the intensity and spatial distribution of deposited activity, and the total health/economic impact of such deposits in assessments of the consequences of accidental releases of radioactivity. The study comprises the influence of various weather conditions on deposition; the resuspension of deposited 137 Cs activity; the weathering of deposits in urban and rural environments; the ultimate fate and dosimetric impact of radionuclides carried by urban run-off water; the impact of the atmosphere's dispersion capabilities. Objectives and results of the four contributions to the project for the reporting period are presented. (R.P.) 5 refs., 4 figs., 1 tab

  10. Mangifera indica as Bioindicator of Mercury Atmospheric Contamination in an ASGM Area in North Gorontalo Regency, Indonesia

    OpenAIRE

    Hendra Prasetia; Masayuki Sakakibara; Koji Omori; Jamie S. Laird; Koichiro Sera; Idham A. Kurniawan

    2018-01-01

    We report the atmospheric Hg contamination in an artisanal and small-scale gold mining (ASGM) area in North Gorontalo, Indonesia. It is well known that atmospheric Hg contaminates the air, water, soil, and living organisms, including trees. In this study, we calculated total weight of heavy metals, especially Hg, and quantitatively measure the concentrations of heavy metals, especially Hg, in tree bark from an ASGM area. Tree bark can be used for the environmental assessment of atmospheric co...

  11. CdTe as a passivating layer in CdTe/HgCdTe heterostructures

    International Nuclear Information System (INIS)

    Virt, I. S.; Kurilo, I. V.; Rudyi, I. A.; Sizov, F. F.; Mikhailov, N. N.; Smirnov, R. N.

    2008-01-01

    CdTe/Hg 1-x Cd x Te heterostructures are studied. In the structures, CdTe is used as a passivating layer deposited as a polycrystal or single crystal on a single-crystal Hg 1-x Cd x Te film. The film and a passivating layer were obtained in a single technological process of molecular beam epitaxy. The structure of passivating layers was studied by reflection high-energy electron diffraction, and the effect of the structure of the passivating layer on the properties of the active layer was studied by X-ray diffractometry. Mechanical properties of heterostructures were studied by the microhardness method. Electrical and photoelectrical parameters of the Hg 1-x Cd x Te films are reported.

  12. Quadrupole moments of the 12+ isomers in 188Hg and 190Hg

    International Nuclear Information System (INIS)

    Dracoulis, G.D.; Lonnroth, T.; Vajda, S.; Dafni, E.; Schatz, G.

    1984-01-01

    The electric quadrupole interaction of the 12 + isomers in 188 Hg and 190 Hg has been measured in solid Hg. The quadrupole moments deduced, vertical strokeQ[ 188 Hg(12 + )]vertical stroke = 91(11) e fm 2 and vertical strokeQ[ 190 Hg(12 + )]vertical stroke = 117(14) e fm 2 suggest a possible change in γ-deformation due to the rotation alignment of the isub(13/2) quasi-neutrons. The temperature dependence of the electric field gradient tensor in Hg was also determined. (orig.)

  13. Short-term variability of 7Be atmospheric deposition and watershed response in a Pacific coastal stream, Monterey Bay, California, USA

    Science.gov (United States)

    Conaway, Christopher H.; Storlazzi, Curt D.; Draut, Amy E.; Swarzenski, Peter W.

    2013-01-01

    Beryllium-7 is a powerful and commonly used tracer for environmental processes such as watershed sediment provenance, soil erosion, fluvial and nearshore sediment cycling, and atmospheric fallout. However, few studies have quantified temporal or spatial variability of 7Be accumulation from atmospheric fallout, and parameters that would better define the uses and limitations of this geochemical tracer. We investigated the abundance and variability of 7Be in atmospheric deposition in both rain events and dry periods, and in stream surface-water samples collected over a ten-month interval at sites near northern Monterey Bay (37°N, 122°W) on the central California coast, a region characterized by a rainy winters, dry summers, and small mountainous streams with flashy hydrology. The range of 7Be activity in rainwater samples from the main sampling site was 1.3–4.4 Bq L−1, with a mean (±standard deviation) of 2.2 ± 0.9 Bq L−1, and a volume-weighted average of 2.0 Bq L−1. The range of wet atmospheric deposition was 18–188 Bq m−2 per rain event, with a mean of 72 ± 53 Bq m−2. Dry deposition fluxes of 7Be ranged from less than 0.01 up to 0.45 Bq m−2 d−1, with an estimated dry season deposition of 7 Bq m−2 month−1. Annualized 7Be atmospheric deposition was approximately 1900 Bq m−2 yr−1, with most deposition via rainwater (>95%) and little via dry deposition. Overall, these activities and deposition fluxes are similar to values found in other coastal locations with comparable latitude and Mediterranean-type climate. Particulate 7Be values in the surface water of the San Lorenzo River in Santa Cruz, California, ranged from −1 to 0.6 Bq g−1, with a median activity of 0.26 Bq g−1. A large storm event in January 2010 characterized by prolonged flooding resulted in the entrainment of 7Be-depleted sediment, presumably from substantial erosion in the watershed. There were too few particulate 7Be data over the storm to accurately model a 7Be load

  14. Export of Atmospheric Mercury from East Asia Observed at Various Monitoring Sites in Taiwan

    Science.gov (United States)

    Sheu, G.; Lin, N.; Wang, J.; Lee, C.; Chang, S.

    2009-12-01

    East Asia is the major atmospheric mercury (Hg) source region in the world due to the excessive coal combustion, industrial emission, and biomass burning in this area. Nonetheless, studies concerning the export of atmospheric Hg from East Asia are still limited. Accordingly, atmospheric Hg has been measured at various sites in Taiwan to study its temporal and spatial distribution, and the significance of long-range transport from the East Asian continent as well. Here we report the data collected in Fu-guei-jiao (121.97°E, 25.47°N, ~30 m a.s.l.), Mt. Bamboo (121.54°E, 25.19°N, 1025 m a.s.l.), and Lulin Atmospheric Background Station (LABS; 120.87°E, 23.47°N, 2862 m a.s.l.) to discuss the atmospheric Hg export from the East Asian continent. Twenty-four hour-integrated total atmospheric Hg (THg) samples were manually collected in Fu-guei-jiao and Mt. Bamboo in 2007-2008 and quantified by dual amalgamation CVAFS. On the other hand, continuous measurements of gaseous elemental Hg (GEM), reactive gaseous Hg (RGM), and particulate Hg (PHg) at LABS began since April 13, 2006 using the Tekran 2537A/1130/1135 speciation system. Mean(±S.D.) THg concentrations were 2.09±0.71 and 1.86±0.50 ng m-3 for Fu-guei-jiao and Mt. Bamboo, respectively. At LABS between April 2006 and April 2009, the mean(±S.D.) concentrations of GEM, RGM and PHg were 1.77±0.54 ng m-3, 22.4±43.8 pg m-3 and 6.3±10.9 pg m-3, respectively. Evident seasonal distribution in THg/GEM concentrations was observed at all sites with higher values usually occurred between fall and spring when the air masses were mainly from the East Asian continent, indicating the influence of the East Asian atmospheric Hg outflow. This also demonstrated that the atmospheric Hg export is occurring both in the boundary layer and in the free troposphere. Concentrations of PHg were usually low at LABS; however, elevated values were detected in spring when the Indochina Peninsula biomass burning plumes frequently affected

  15. Mercury biogeochemical cycling in the ocean and policy implications.

    Science.gov (United States)

    Mason, Robert P; Choi, Anna L; Fitzgerald, William F; Hammerschmidt, Chad R; Lamborg, Carl H; Soerensen, Anne L; Sunderland, Elsie M

    2012-11-01

    Anthropogenic activities have enriched mercury in the biosphere by at least a factor of three, leading to increases in total mercury (Hg) in the surface ocean. However, the impacts on ocean fish and associated trends in human exposure as a result of such changes are less clear. Here we review our understanding of global mass budgets for both inorganic and methylated Hg species in ocean seawater. We consider external inputs from atmospheric deposition and rivers as well as internal production of monomethylmercury (CH₃Hg) and dimethylmercury ((CH₃)₂Hg). Impacts of large-scale ocean circulation and vertical transport processes on Hg distribution throughout the water column and how this influences bioaccumulation into ocean food chains are also discussed. Our analysis suggests that while atmospheric deposition is the main source of inorganic Hg to open ocean systems, most of the CH₃Hg accumulating in ocean fish is derived from in situ production within the upper waters (ocean basins are changing at different rates due to differences in atmospheric loading and that the deeper waters of the oceans are responding slowly to changes in atmospheric Hg inputs. Most biological exposures occur in the upper ocean and therefore should respond over years to decades to changes in atmospheric mercury inputs achieved by regulatory control strategies. Migratory pelagic fish such as tuna and swordfish are an important component of CH₃Hg exposure for many human populations and therefore any reduction in anthropogenic releases of Hg and associated deposition to the ocean will result in a decline in human exposure and risk. Copyright © 2012 Elsevier Inc. All rights reserved.

  16. Projecting Soil Feedbacks to Atmospheric CO2 Following Erosion and Deposition on Centennial Timescales in Two Contrasting Forests: A Study of Critical Zone-Atmosphere Exchange

    Science.gov (United States)

    Billings, S. A.; Richter, D., Jr.; Ziegler, S. E.; Prestegaard, K. L.

    2016-12-01

    For almost 20 y there has been a growing recognition that erosion and associated lateral movement of SOC does not necessarily result in a net CO2 source from terrestrial sources to the atmosphere. Eroded SOC may undergo mineralization to CO2 at a more rapid pace than it would have in situ, but the eroding ecosystem continues to generate SOC at a potentially modified rate, and the eroding profile may also experience changing SOC mineralization rates. No one knows how these process rates may change upon erosion. Years ago, we introduced a model that computes the influence of erosion on biosphere-atmosphere CO2 exchange for any profile of interest. The model permits the user to test how assumptions of changing SOC production and mineralization can influence the degree to which erosion induces a net CO2 sink or source. Here we present an analogous model depicting how deposition of eroded SOC also can result in altered biosphere-atmosphere CO2 exchange. We employ both models to investigate how erosion and deposition in two contrasting forested regions may influence regional C budgets. Runoff-induced erosion in a boreal forest occurs at low rates, but removes C-rich, organic material; anthropogenically-enhanced erosion in a warm temperate forest removed both O- and mineral-rich A-horizons. Model runs (100 y) suggest that even though the great volume of mineral soil eroded from the temperate forest was relatively low-SOC, high erosion rates prompted greater potential for erosion to serve as a net CO2 sink compared to the boreal forest where C-rich material was lost but erosion rates remained low. The models further suggest that changes in SOC production and mineralization at eroding sites in both forest types are a greater influence on CO2 source or sink strength than analogous changes at depositional sites. The fate of eroded material and the influence of erosion and deposition on SOC dynamics remain knowledge gaps critical for projecting atmospheric CO2.

  17. Tracing aquatic bioavailable Hg in three different regions of China using fish Hg isotopes.

    Science.gov (United States)

    Liu, Cheng-Bin; Hua, Xiu-Bing; Liu, Hong-Wei; Yu, Ben; Mao, Yu-Xiang; Wang, Ding-Yong; Yin, Yong-Guang; Hu, Li-Gang; Shi, Jian-Bo; Jiang, Gui-Bin

    2018-04-15

    To trace the most concerned bioavailable mercury (Hg) in aquatic environment, fish samples were collected from three typical regions in China, including 3 rivers and 1 lake in the Tibetan Plateau (TP, a high altitude background region with strong solar radiation), the Three Gorges Reservoir (TGR, the largest artificial freshwater reservoir in China), and the Chinese Bohai Sea (CBS, a heavily human-impacted semi-enclosed sea). The Hg isotopic compositions in fish muscles were analyzed. The results showed that anthropogenic emissions were the main sources of Hg in fish from TGR and CBS because of the observed negative δ 202 Hg and positive Δ 199 Hg in these two regions (TGR, δ 202 Hg: - 0.72 to - 0.29‰, Δ 199 Hg: 0.15 - 0.52‰; CBS, δ 202 Hg: - 2.09 to - 0.86‰, Δ 199 Hg: 0.07 - 0.52‰). The relatively higher δ 202 Hg and Δ 199 Hg (δ 202 Hg: - 0.37 - 0.08‰, Δ 199 Hg: 0.50 - 1.89‰) in fish from TP suggested the insignificant disturbance from local anthropogenic activities. The larger slopes of Δ 199 Hg/Δ 201 Hg in fish from TGR (1.29 ± 0.14, 1SD) and TP (1.25 ± 0.06, 1SD) indicated methylmercury (MeHg) was produced and photo-reduced in the water column before incorporation into the fish. In contrast, the photoreduction of Hg 2+ was the main process in CBS (slope of Δ 199 Hg/Δ 201 Hg: 1.06 ± 0.06, 1SD). According to the fingerprint data of Hg isotopes, the most important source for aquatic bioavailable Hg in TP should be the long-range transported Hg, contrasting to the anthropogenic originated MeHg from surface sediments and runoffs in TGR and inorganic Hg from continental inputs in CBS. Therefore, the isotopic signatures of Hg in fish can provide novel clues in tracing sources and behaviors of bioavailable Hg in aquatic systems, which are critical for further understanding the biogeochemical cycling of Hg. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. Further promotion of the use of mosses and lichens for studies of atmospheric deposition of trace elements

    International Nuclear Information System (INIS)

    Steinnes, Eiliv

    2001-01-01

    Some recent and ongoing studies related to the use of mosses as biomonitors of atmospheric metal deposition are briefly reviewed. Issues discussed in particular are the conversion of concentration in moss to absolute deposition values, introduction of a second-generation ICP-MS instrument for moss analysis, determination of stable lead isotope ratios in mosses for source apportionment, and temporal trends of lead and cadmium deposition in Norway. A novel nuclear technique for the determination of fluorine in mosses surrounding an aluminium smelter is presented. (author)

  19. Emission, transport, deposition, and re-suspension of radionuclides from Fukushima Dai-ichi Nuclear Power Plant in the atmosphere - Overview of 2-year investigations in Japan

    Science.gov (United States)

    Kita, Kazuyuki; Igarashi, Yasuhiro; Yoshida, Naohiro; Nakajima, Teruyuki

    2013-04-01

    Following a huge earthquake and tsunami in Eastern Japan on 11 March, 2011, the accident in Fukushima Dai-ichi Nuclear Power Plant (FDNPP) occurred to emit a large amount of artificial radionuclides to the environment. Soon after the FDNPP accident, many Japanese researchers, as well as researchers in other countries, started monitoring radionuclides in various environmental fields and/or model calculations to understand extent and magnitude of radioactive pollution. In this presentation, we overview these activities for the atmospheric radionuclides in Japan as followings: 1. Investigations to evaluate radionuclide emissions by explosions at FNDPP in March 2011 and to estimate the respiration dose of the radiation at this stage. 2. Investigations to evaluate atmospheric transport and deposition processes of atmospheric radionuclide to determine the extent of radionuclide pollution. -- Based on results of the regular and urgent monitoring results, as well as the mapping of the distribution of radionuclide s accumulated by the deposition to the ground, restoration of their time-dependent emission rates has been tried, and processes determining atmospheric concentration and deposition to the ground have been investigated by using the model calculations. 3. Monitoring of the atmospheric concentrations of radionuclide after the initial, surge phase of FNDPP accident. 4. Investigations to evaluate re-suspension of radionuclide from the ground, including the soil and the vegetation. -- Intensive monitoring of the atmospheric concentrations and deposition amount of radionuclide after the initial, surge phase of the accident enable us to evaluate emission history from FNDPP, atmospheric transport and deposition processes, chemical and physical characteristics of atmospheric radionuclide especially of radio cesium, and re-suspension processes which has become dominant process to supply radio cesium to the atmosphere recently.

  20. A heavy metal atmospheric deposition study in the South Ural mountains

    International Nuclear Information System (INIS)

    Frontas'eva, M.V.; Smirnov, L.I.; Steinnes, E.; Lyapunov, S.M.; Cherchintsev, V.D.

    2002-01-01

    Samples of the mosses Hylocomium splendens and Pleurozium schreberi, collected in the summer of 1998, were used to study the atmospheric deposition of heavy metals and other toxic elements in the Chelyabinsk Region situated in the South Ural, one of the most heavily poluted industrial areas of the Russian Federation. Samples of natural soils were collected simultaneously with moss at the same 30 sites in order to investigate surface accumulation of heavy metals and to examine the correlation of elements in moss and soil samples in order to separate contributions from atmospheric deposition and from soil minerals. A total of 38 elements (Na, Mg, Al, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, As, Se, Rb, Sr, Zr, Mo, Sb, Cs, Ba, La, Ce, Nd, Sm, Eu, Gd, Tb, Dy, Yb, Hf, Tf, W, Au, Th, U) in soil and 33 elements (Na, Mg, Al, Cl, K, Ca, Sc, V, Cr, Mn, Fe, Co, Ni, Zn, As, Se, Br, Rb, Ag, Sb, Cs, Ba, La, Ce, Sm, Tb, Yb, Hf, Ta, W, Au, Th, U) in mosses were determined by epithermal neutron activation analysis, The elements Cu, Cd and Pb (in moss samples only) were obtained by atomic absorption spectrometry. The element concentrations were compared to those for copper basins in Poland and Serbia as well as to baseline concentrations in Norway. VARIMAX rotated principal component analysis was used to identify and characterise different pollution sources and to point out the most polluted areas

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

    Science.gov (United States)

    Filippelli, G. M.

    2016-12-01

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

  2. Potassium limits potential growth of bog vegetation under elevated atmospheric CO2 and N deposition

    NARCIS (Netherlands)

    Hoosbeek, M.R.; Breemen, van N.; Vasander, H.; Buttlers, A.; Berendse, F.

    2002-01-01

    The free air carbon dioxide enrichment (FACE) and N deposition experiments on four ombrotrophic bogs in Finland, Sweden, the Netherlands and Switzerland, revealed that after three years of treatment: (1) elevated atmospheric CO2 concentration had no significant effect on the biomass growth of

  3. Long-term atmospheric wet deposition of dissolved organic nitrogen in a typical red-soil agro-ecosystem, Southeastern China.

    Science.gov (United States)

    Cui, Jian; Zhou, Jing; Peng, Ying; He, Yuan Q; Yang, Hao; Xu, Liang J; Chan, Andy

    2014-05-01

    Dissolved organic nitrogen (DON) from atmospheric deposition has been a growing concern in the world and atmospheric nitrogen (N) deposition is increasing quickly in China especially Southeastern China. In our study, DON wet deposition was estimated by collecting and analyzing rainwater samples continuously over eight years (2005-2012) in a typical red-soil farmland ecosystem, Southeast China. Results showed that the volume-weighted-average DON concentration varied from 0.2 to 3.3 mg N L(-1) with an average of 1.2 mg N L(-1). DON flux ranged from 5.7 to 71.6 kg N ha(-1) year(-1) and averaged 19.7 kg N ha(-1) year(-1) which accounted for 34.6% of the total dissolved nitrogen (TDN) in wet deposition during the eight-year period. Analysis of DON concentration and flux, contribution of DON to TDN, rainfall, rain frequency, air temperature and wind frequency and the application of pig manure revealed possible pollution sources. Significant positive linear relation of annual DON flux and usage of pig manure (Pcycle in the red-soil agro-ecosystem in the future.

  4. Nitrogen concentrations in mosses indicate the spatial distribution of atmospheric nitrogen deposition in Europe

    Energy Technology Data Exchange (ETDEWEB)

    Harmens, H., E-mail: hh@ceh.ac.uk [Centre for Ecology and Hydrology, Environment Centre Wales, Deiniol Road, Bangor, Gwynedd LL57 2UW (United Kingdom); Norris, D.A., E-mail: danor@ceh.ac.uk [Centre for Ecology and Hydrology, Environment Centre Wales, Deiniol Road, Bangor, Gwynedd LL57 2UW (United Kingdom); Cooper, D.M., E-mail: cooper@ceh.ac.uk [Centre for Ecology and Hydrology, Environment Centre Wales, Deiniol Road, Bangor, Gwynedd LL57 2UW (United Kingdom); Mills, G., E-mail: gmi@ceh.ac.uk [Centre for Ecology and Hydrology, Environment Centre Wales, Deiniol Road, Bangor, Gwynedd LL57 2UW (United Kingdom); Steinnes, E., E-mail: Eiliv.Steinnes@chem.ntnu.no [Department of Chemistry, Norwegian University of Science and Technology, 7491 Trondheim (Norway); Kubin, E., E-mail: Eero.Kubin@metla.fi [Finnish Forest Research Institute, Kirkkosaarentie 7, 91500 Muhos (Finland); Thoeni, L., E-mail: lotti.thoeni@fub-ag.ch [FUB-Research Group for Environmental Monitoring, Alte Jonastrasse 83, 8640 Rapperswil (Switzerland); Aboal, J.R., E-mail: jesusramon.aboal@usc.es [University of Santiago de Compostela, Faculty of Biology, Department of Ecology, 15782 Santiago de Compostela (Spain); Alber, R., E-mail: Renate.Alber@provinz.bz.it [Environmental Agency of Bolzano, 39055 Laives (Italy); Carballeira, A., E-mail: alejo.carballeira@usc.es [University of Santiago de Compostela, Faculty of Biology, Department of Ecology, 15782 Santiago de Compostela (Spain); Coskun, M., E-mail: coskunafm@yahoo.com [Canakkale Onsekiz Mart University, Faculty of Medicine, Department of Medical Biology, 17100 Canakkale (Turkey); De Temmerman, L., E-mail: ludet@var.fgov.be [Veterinary and Agrochemical Research Centre, Tervuren (Belgium); Frolova, M., E-mail: marina.frolova@lvgma.gov.lv [Latvian Environment, Geology and Meteorology Agency, Riga (Latvia); Gonzalez-Miqueo, L., E-mail: lgonzale2@alumni.unav.es [Univ. of Navarra, Irunlarrea No 1, 31008 Pamplona (Spain)

    2011-10-15

    In 2005/6, nearly 3000 moss samples from (semi-)natural location across 16 European countries were collected for nitrogen analysis. The lowest total nitrogen concentrations in mosses (<0.8%) were observed in northern Finland and northern UK. The highest concentrations ({>=}1.6%) were found in parts of Belgium, France, Germany, Slovakia, Slovenia and Bulgaria. The asymptotic relationship between the nitrogen concentrations in mosses and EMEP modelled nitrogen deposition (averaged per 50 km x 50 km grid) across Europe showed less scatter when there were at least five moss sampling sites per grid. Factors potentially contributing to the scatter are discussed. In Switzerland, a strong (r{sup 2} = 0.91) linear relationship was found between the total nitrogen concentration in mosses and measured site-specific bulk nitrogen deposition rates. The total nitrogen concentrations in mosses complement deposition measurements, helping to identify areas in Europe at risk from high nitrogen deposition at a high spatial resolution. - Highlights: > Nitrogen concentrations in mosses were determined at ca. 3000 sites across Europe. > Moss concentrations were compared with EMEP modelled nitrogen deposition. > The asymptotic relationship for Europe showed saturation at ca. 15 kg N ha{sup -1} y{sup -1}. > Linear relationships were found with measured nitrogen deposition in some countries. > Moss concentrations complement deposition measurements at high spatial resolution. - Mosses as biomonitors of atmospheric nitrogen deposition in Europe.

  5. Equilibrium mercury isotope fractionation between dissolved Hg(II) species and thiol-bound Hg

    NARCIS (Netherlands)

    Wiederhold, Jan G.; Cramer, Christopher J.; Daniel, Kelly; Infante, Ivan; Bourdon, Bernard; Kretzschmar, Ruben

    2010-01-01

    Stable Hg isotope ratios provide a new tool to trace environmental Hg cycling. Thiols (-SH) are the dominant Hg-binding groups in natural organic matter. Here, we report experimental and computational results on equilibrium Hg isotope fractionation between dissolved Hg(II) species and thiol-bound

  6. Influence of long-range transboundary transport on atmospheric water vapor mercury collected at the largest city of Tibet

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Jie [Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101 (China); CAS Center for Excellence in Tibetan Plateau Earth Sciences, Chinese Academy of Sciences, Beijing 100101 (China); Laboratory of Green Chemistry, Lappeenranta University of Technology, Sammonkatu 12, Mikkeli FI 50130 (Finland); Kang, Shichang, E-mail: shichang.kang@lzb.ac.cn [State Key Laboratory of Cryospheric Sciences, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000 (China); CAS Center for Excellence in Tibetan Plateau Earth Sciences, Chinese Academy of Sciences, Beijing 100101 (China); Tian, Lide [Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101 (China); CAS Center for Excellence in Tibetan Plateau Earth Sciences, Chinese Academy of Sciences, Beijing 100101 (China); Guo, Junming [Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101 (China); Graduate University of the Chinese Academy of Sciences, Beijing 100049 (China); Zhang, Qianggong; Cong, Zhiyuan [Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101 (China); CAS Center for Excellence in Tibetan Plateau Earth Sciences, Chinese Academy of Sciences, Beijing 100101 (China); Sillanpää, Mika [Laboratory of Green Chemistry, Lappeenranta University of Technology, Sammonkatu 12, Mikkeli FI 50130 (Finland); and others

    2016-10-01

    Monsoon circulation is an important process that affects long-range transboundary transport of anthropogenic contaminants such as mercury (Hg). During the Indian monsoon season of 2013, a total of 92 and 26 atmospheric water vapor samples were collected at Lhasa, the largest city of the Tibet, for Hg and major ions analysis, respectively. The relatively low pH/high electronic conductivity values, together with the fact that NH{sub 4}{sup +} in atmospheric water vapor was even higher than that determined in precipitation of Lhasa, indicated the effects of anthropogenic perturbations through long-range transboundary atmospheric transport. Concentrations of Hg in atmospheric water vapor ranged from 2.5 to 73.7 ng L{sup −1}, with an average of 12.5 ng L{sup −1}. The elevated Hg and major ions concentrations, and electronic conductivity values were generally associated with weak acidic samples, and Hg mainly loaded with anthropogenic ions such as NH{sub 4}{sup +}. The results of principal component analysis and trajectory analysis suggested that anthropogenic emissions from the Indian subcontinent may have largely contributed to the determined Hg in atmospheric water vapor. Furthermore, our study reconfirmed that below-cloud scavenging contribution was significant for precipitation Hg in Lhasa, and evaluated that on average 74.1% of the Hg in precipitation could be accounted for by below-cloud scavenging. - Highlights: • The low pH/high electronic conductivity was found in atmospheric water vapor. • Anthropogenic NH{sub 4}{sup +} was higher than that determined in precipitation of Lhasa. • Elevated Hg and major ions levels were usually associated with weak acidic samples. • Hg in atmospheric water vapor was largely influenced by transboundary transport. • Below-cloud scavenging accounted for most Hg in precipitation.

  7. Influence of long-range transboundary transport on atmospheric water vapor mercury collected at the largest city of Tibet

    International Nuclear Information System (INIS)

    Huang, Jie; Kang, Shichang; Tian, Lide; Guo, Junming; Zhang, Qianggong; Cong, Zhiyuan; Sillanpää, Mika

    2016-01-01

    Monsoon circulation is an important process that affects long-range transboundary transport of anthropogenic contaminants such as mercury (Hg). During the Indian monsoon season of 2013, a total of 92 and 26 atmospheric water vapor samples were collected at Lhasa, the largest city of the Tibet, for Hg and major ions analysis, respectively. The relatively low pH/high electronic conductivity values, together with the fact that NH_4"+ in atmospheric water vapor was even higher than that determined in precipitation of Lhasa, indicated the effects of anthropogenic perturbations through long-range transboundary atmospheric transport. Concentrations of Hg in atmospheric water vapor ranged from 2.5 to 73.7 ng L"−"1, with an average of 12.5 ng L"−"1. The elevated Hg and major ions concentrations, and electronic conductivity values were generally associated with weak acidic samples, and Hg mainly loaded with anthropogenic ions such as NH_4"+. The results of principal component analysis and trajectory analysis suggested that anthropogenic emissions from the Indian subcontinent may have largely contributed to the determined Hg in atmospheric water vapor. Furthermore, our study reconfirmed that below-cloud scavenging contribution was significant for precipitation Hg in Lhasa, and evaluated that on average 74.1% of the Hg in precipitation could be accounted for by below-cloud scavenging. - Highlights: • The low pH/high electronic conductivity was found in atmospheric water vapor. • Anthropogenic NH_4"+ was higher than that determined in precipitation of Lhasa. • Elevated Hg and major ions levels were usually associated with weak acidic samples. • Hg in atmospheric water vapor was largely influenced by transboundary transport. • Below-cloud scavenging accounted for most Hg in precipitation.

  8. Depositional characteristics of atmospheric polybrominated diphenyl ethers on tree barks

    Directory of Open Access Journals (Sweden)

    Man Young Chun

    2014-07-01

    Full Text Available Objectives This study was conducted to determine the depositional characteristics of several tree barks, including Ginkgo (Ginkgo biloba, Pine (Pinus densiflora, Platanus (Platanus, and Metasequoia (Metasequoia glyptostroboides. These were used as passive air sampler (PAS of atmospheric polybrominated diphenyl ethers (PBDEs. Methods Tree barks were sampled from the same site. PBDEs were analyzed by highresolution gas chromatography/high-resolution mass spectrometer, and the lipid content was measured using the gravimetric method by n-hexane extraction. Results Gingko contained the highest lipid content (7.82 mg/g dry, whereas pine (4.85 mg/g dry, Platanus (3.61 mg/g dry, and Metasequoia (0.97 mg/g dry had relatively lower content. The highest total PBDEs concentration was observed in Metasequoia (83,159.0 pg/g dry, followed by Ginkgo (53,538.4 pg/g dry, Pine (20,266.4 pg/g dry, and Platanus (12,572.0 pg/g dry. There were poor correlations between lipid content and total PBDE concentrations in tree barks (R2=0.1011, p =0.682. Among the PBDE congeners, BDE 206, 207 and 209 were highly brominated PBDEs that are sorbed to particulates in ambient air, which accounted for 90.5% (84.3-95.6% of the concentration and were therefore identified as the main PBDE congener. The concentrations of particulate PBDEs deposited on tree barks were dependent on morphological characteristics such as surface area or roughness of barks. Conclusions Therefore, when using the tree barks as the PAS of the atmospheric PBDEs, samples belonging to same tree species should be collected to reduce errors and to obtain reliable data.

  9. 46 CFR 53.10-3 - Inspection and tests (modifies HG-500 through HG-540).

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Inspection and tests (modifies HG-500 through HG-540... tests (modifies HG-500 through HG-540). (a) The inspections required by HG-500 through HG-540 must be performed by the “Authorized Inspector” as defined in HG-515 of section IV of the ASME Boiler and Pressure...

  10. Mercury in precipitation over the coastal zone of the southern Baltic Sea, Poland.

    Science.gov (United States)

    Siudek, Patrycja; Falkowska, Lucyna; Brodecka, Aleksandra; Kowalski, Artur; Frankowski, Marcin; Siepak, Jerzy

    2015-02-01

    An investigation of atmospheric mercury was conducted in the urban coastal zone of the Gulf of Gdansk (Baltic Sea, Poland) in 2008. Rainwater samples were collected in bulk samplers and Hg concentration was determined using AAS method. Total mercury concentration ranged from 1.9 to 14.8 ng l(-1) (the mean was 8.3 ng l(-1) with standard deviation ±3.7), out of which about 34 % were water-soluble Hg(II) forms. Distribution of Hg species in rainwater was related to both the emission source and the atmospheric processes. During the sampling period, two maxima of Hg concentration in precipitation were observed: the first in the cold season and the second one in the warm season. Elevated concentrations of Hg in wintertime precipitation were generally the result of local urban atmospheric emission connected with the following anthropogenic sources: intensive combustion of fossil fuels in domestic furnaces, individual power/heat generating plants, and motor vehicles. During summertime, Hg° re-emitted from contaminated land and sea surfaces was photochemically oxidized by active atmospheric substances (e.g., hydroxyl radicals, hydrogen peroxide, halogens) and could be an additional source of atmospherically deposited Hg. The results presented in this work indicate that rainwater Hg concentration and deposition values are not much higher in comparison with other urban locations along the Baltic Sea basin and other coastal cities. However, the elevated mercury concentration in rainwater and, consequently, higher deposition ratio could appear occasionally as an effect of intensive anthropogenic emissions (domestic heating) and/or photochemical reactions.

  11. Atmospheric deposition and surface stratification as controls of contrasting chlorophyll abundance in the North Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Patra, P.K.; DileepKumar, M.; Mahowald, N.; Sarma, V.V.S.S.

    Intense upwelling during summer and convection in winter are believed to drive higher biological productivity in the Arabian Sea than in the Bay of Bengal. Although the Arabian Sea receives substantial atmospheric deposition of dust aerosols, its...

  12. Lattice defects in semiconducting Hg/1-x/Cd/x/Te alloys. I - Defect structure of undoped and copper doped Hg/0.8/Cd/0.2/Te. II - Defect structure of indium-doped Hg/0.8/Cd/0.2/Te

    Science.gov (United States)

    Vydyanath, H. R.

    1981-01-01

    Hall effect and mobility measurements were conducted on undoped Hg(0.8)Cd(0.2)Te crystals which were quenched to room temperature after being subjected to equilibration at temperatures ranging from 400 to 655 C in various Hg atmospheres. The variation of the hole concentration in the cooled crystals at 77 K as a function of Hg's partial pressure at the equilibration temperature, together with a comparison of the hole mobility in the undoped samples with that in copper-doped ones, yields a defect model for the undoped crystals according to which they are intrinsic at the equilibration temperatures and the native acceptor defects are doubly ionized. In the second part of this paper, the effects of indium doping are considered. The concentration of electrons obtained in the cooled crystals was found to be lower than the intrinsic carrier concentration at the equilibration temperatures. A defect model is proposed according to which most of the indium is incorporated as In2Te3(s) dissolved in the crystal, with only a small fraction of indium acting as single donors occupying Hg lattice sites.

  13. Factors Controlling the Distribution of Atmospheric Mercury in the East Asian Free Troposphere

    Science.gov (United States)

    Sheu, G.; Lee, C.; Lin, N.; Wang, J.; Ouyang, C.

    2008-12-01

    Taiwan is located to the downwind side of both East and Southeast Asia, which are the major anthropogenic mercury (Hg) source region worldwide. Also, it has been suggested that mountain-top monitoring sites, which are frequently in the free troposphere, are essential to the understanding of the global Hg transport. Accordingly, continuous measurements of atmospheric Hg have been conducting at Lulin Atmospheric Background Station (LABS, 2862 m a.s.l.) in Taiwan since April 13, 2006 to study the trans-boundary transport and transformation of Hg in the free troposphere. Three types of atmospheric Hg, including gaseous elemental Hg (GEM), reactive gaseous Hg (RGM), and particulate Hg (PHg), are measured using the Tekran 2537A/1130/1135 speciation system. Diurnal variations in the concentrations of GEM, RGM, ozone, and water vapor (WV) mixing ratio indicated the influence of boundary layer air in daytime and the subsidence of free tropospheric air masses from higher altitudes at night. Seasonal variation in GEM concentrations was evident with elevated concentrations usually observed between fall and spring when air masses were more or less under the influence of Asian continent. Low summer GEM values were associated with marine air masses. Spikes of RGM were frequently detected between midnight and early morning with concurrent decreases in GEM and WV mixing ratio and increases in ozone concentrations, suggesting the oxidation of GEM and formation of RGM in free troposphere. Concentrations of PHg were usually low; however, elevated concentrations were detected in spring when the Southeast Asian biomass burning plumes affected the LABS. Analysis of the collected data indicate that at LABS the distribution of atmospheric Hg is dynamically controlled by background atmosphere, exchange and mixing of free troposphere/boundary layer air, chemical transformation, and long-range transport from East and Southeast Asia.

  14. Characterization of atmospheric deposition and runoff water on a small suburban catchment

    OpenAIRE

    LAMPREA, Diana Katerine; RUBAN, Véronique

    2011-01-01

    A study of air quality and atmospheric deposition on a small urban catchment (Pin Sec catchment) has been carried out in Nantes, France, in 2007 and 2008 in the frame of a federative project aimed at understanding the origin of pollution in urban environments. Carbon monoxide, nitrogen monoxide, nitrogen dioxide, ozone, sulphur dioxide and particles less than 10 µm (PM 10) were monitored for air quality, whereas heavy metals, Polycyclic aromatic hydrocarbons (PAHs) and pesticides were analyze...

  15. Simple and green synthesis of piperazine-grafted reduced graphene oxide and its application for the detection of Hg(II)

    Science.gov (United States)

    Zuo, Yinxiu; Xu, Jingkun; Xing, Huakun; Duan, Xuemin; Lu, Limin; Ye, Guo; Jia, Haiyan; Yu, Yongfang

    2018-04-01

    In this paper, piperazine-grafted reduced graphene oxide (NH-rGO) was synthesized via a simple and green two-step procedure: (i) opening of the resulting epoxides of graphene oxide (GO) with piperazine (NH) through nucleophilic substitution; (ii) reduction of GO with ascorbic acid. Its structure and morphology were characterized by scanning electron microscopy and x-ray photoelectron spectroscopy. The NH-rGO modified glassy carbon electrode was explored as an electrochemical sensor for the determination of Hg(II) using a differential pulse anodic stripping voltammetry technique. Hg(II) can be efficiently accumulated and deposited on the surface of a modified electrode by strong coordination chemical bonds formed between Hg(II) and NH. And then the anodic stripping current can be significantly enhanced by rGO with the merits of large specific surface area and high conductivity, which served as a signal amplifier, finally realizing the highly sensitive determination of Hg(II). The experimental parameters including the pH value of the acetate buffer, deposition potential and deposition time were optimized. Under optimal conditions, the developed sensor exhibited a wide linear range from 0.4-12 000 nM with a low limit of detection of 0.2 nM, which is well below the guideline value in drinking water set by the WHO. Moreover, the practical application of this method was confirmed by an assay of Hg(II) in tap water samples with acceptable results.

  16. An Artificial Turf-Based Surrogate Surface Collector for the Direct Measurement of Atmospheric Mercury Dry Deposition

    Directory of Open Access Journals (Sweden)

    Naima L. Hall

    2017-02-01

    Full Text Available This paper describes the development of a new artificial turf surrogate surface (ATSS sampler for use in the measurement of mercury (Hg dry deposition. In contrast to many existing surrogate surface designs, the ATSS utilizes a three-dimensional deposition surface that may more closely mimic the physical structure of many natural surfaces than traditional flat surrogate surface designs (water, filter, greased Mylar film. The ATSS has been designed to overcome several complicating factors that can impact the integrity of samples with other direct measurement approaches by providing a passive system which can be deployed for both short and extended periods of time (days to weeks, and is not contaminated by precipitation and/or invalidated by strong winds. Performance characteristics including collocated precision, in-field procedural and laboratory blanks were evaluated. The results of these performance evaluations included a mean collocated precision of 9%, low blanks (0.8 ng, high extraction efficiency (97%–103%, and a quantitative matrix spike recovery (100%.

  17. Mercury isotope constraints on the source for sediment-hosted lead-zinc deposits in the Changdu area, southwestern China

    Science.gov (United States)

    Xu, Chunxia; Yin, Runsheng; Peng, Jiantang; Hurley, James P.; Lepak, Ryan F.; Gao, Jianfeng; Feng, Xinbin; Hu, Ruizhong; Bi, Xianwu

    2018-03-01

    The Lanuoma and Cuona sediment-hosted Pb-Zn deposits hosted by Upper Triassic limestone and sandstone, respectively, are located in the Changdu area, SW China. Mercury concentrations and Hg isotopic compositions from sulfide minerals and potential source rocks (e.g., the host sedimentary rocks and the metamorphic basement) were investigated to constrain metal sources and mineralization processes. In both deposits, sulfide minerals have higher mercury (Hg) concentrations (0.35 to 1185 ppm) than the metamorphic basement rocks (0.05 to 0.15 ppm) and sedimentary rocks (0.02 to 0.08 ppm). Large variations of mass-dependent fractionation (3.3‰ in δ202Hg) and mass-independent fractionation (0.3‰ in Δ199Hg) of Hg isotopes were observed. Sulfide minerals have Hg isotope signatures that are similar to the hydrothermal altered rocks around the deposit, and similar to the metamorphic basement, but different from barren sedimentary rocks. The variation of Δ199Hg suggests that Hg in sulfides was mainly derived from the underlying metamorphic basement. Mercury isotopes could be a geochemical tracer in understanding metal sources in hydrothermal ore deposits.

  18. A fluvial mercury budget for Lake Ontario.

    Science.gov (United States)

    Denkenberger, Joseph S; Driscoll, Charles T; Mason, Edward; Branfireun, Brian; Warnock, Ashley

    2014-06-03

    Watershed mercury (Hg) flux was calculated for ten inflowing rivers and the outlet for Lake Ontario using empirical measurements from two independent field-sampling programs. Total Hg (THg) flux for nine study watersheds that directly drain into the lake ranged from 0.2 kg/yr to 13 kg/yr, with the dominant fluvial THg load from the Niagara River at 154 kg/yr. THg loss at the outlet (St. Lawrence River) was 68 kg/yr and has declined approximately 40% over the past decade. Fluvial Hg inputs largely (62%) occur in the dissolved fraction and are similar to estimates of atmospheric Hg inputs. Fluvial mass balances suggest strong in-lake retention of particulate Hg inputs (99%), compared to dissolved total Hg (45%) and methyl Hg (22%) fractions. Wetland land cover is a good predictor of methyl Hg yield for Lake Ontario watersheds. Sediment deposition studies, coupled atmospheric and fluvial Hg fluxes, and a comparison of this work with previous measurements indicate that Lake Ontario is a net sink of Hg inputs and not at steady state likely because of recent decreases in point source inputs and atmospheric Hg deposition.

  19. Expanding atmospheric acid deposition in China from the 1990s to the 2010s

    Science.gov (United States)

    Yu, Haili; Wang, Qiufeng

    2017-04-01

    Atmospheric acid deposition is considered a global environmental issue. China has been experiencing serious acid deposition, which is anticipated to be more serious with the country's economic development and increasing consumption of fossil fuels in recent decades. By collecting nationwide data on pH and concentrations of sulfate (SO42-) and nitrate (NO3-) in precipitation between 1980 and 2014 in China, we explored the spatiotemporal variations of precipitation acid deposition (bulk deposition) and their influencing factors. Our results showed that average precipitation pH values were 4.86 and 4.84 in the 1990s and 2010s, respectively. This suggests that precipitation acid deposition in China has not seriously changes. Average SO42- deposition declined from 30.73 to 28.61 kg S ha-1 yr-1 but average NO3- deposition increased from 4.02 to 6.79 kg N ha-1 yr-1. Specifically, the area of severe precipitation acid deposition in southern China has shrunk to some extent as a result of decreasing pollutant emissions, whereas the area of moderate precipitation acid deposition has expanded in northern China, associated with rapid industrial and transportation development. Significant positive correlations have been found between precipitation acid deposition, energy consumption, and rainfall. Our findings provide a comprehensive evaluation of the spatiotemporal dynamics of precipitation acid deposition in China over past three decades, and confirm the idea that strategies implemented to save energy and reduce pollutant emissions in China have been effective in alleviating precipitation acid deposition. These findings might be used to demonstrate how developing countries could achieve economic development and environmental protection through the implementation of advanced technologies to reduce pollutant emissions.