Long-term Atmospheric Deposition Research Articles

The changing nitrogen landscape of United States streams: Declining deposition and increasing organic nitrogen.

Air quality regulations have led to decreased nitrogen (N) and sulfur deposition across the conterminous United States (CONUS) during the last several decades, particularly in the eastern parts. But it is unclear if declining deposition has altered stream N at large scales. We compared watershed N inputs with N chemistry from over 2,000 CONUS streams where deposition was the largest N input to the watershed. Weighted change analysis showed that deposition declined across most watersheds, especially in the Eastern CONUS. Nationally, declining N deposition was not associated with significant large-scale declines in stream nitrate concentration. Instead, significant increases in stream dissolved organic carbon (DOC) and total organic N (TON) were widespread across regions. Possible mechanisms behind these increases include declines in acidity and/or ionic strength drivers, changes in carbon availability, and/or climate variables. Our results also reveal a declining trend of DOC/TON ratio over the entire study period, primarily influenced by the trend in the Eastern region, suggesting the rate of increase in stream TON exceeded the rate of increase in DOC concentration during this period. Our results illustrate the complexity of nutrient cycling that links long-term atmospheric deposition to water quality. More research is needed to understand how increased dissolved organic N could affect aquatic ecosystems and downstream riverine nutrient export.

Distribution and impacts of contamination by natural and artificial radionuclides in attic dust and urban soil samples from a former industrial Hungarian city: A case study from Salgótarján

Primordial radionuclides can be found in all environmental compartments. Since coal-fired power plants (CFPP) can be a source of additional radionuclide contamination because coal contains natural radioactive isotopes such as 238U (226Ra) and 232Th. This study investigated the impact of such possible radionuclide contamination from former heavy industrial activities, namely a former local coal-fired power plant, in urban soils and attic dust in Salgótarján, Hungary. Even today, industrial by-products, e.g., coal ash, in this city represent significant threat to its residents. A total of 36 attic dust samples (family houses, kindergartens, churches and blockhouses) were collected and 19 urban soil samples (playgrounds, kindergartens, parks and others) were selected no further than 500 m from the corresponding attic dust sampling sites. Additionally, a coal ash and a brown forest soil sample were also collected to differentiate between the anthropogenic and geogenic sources in the residential area. The sampled houses, built between 1890 and 1990, are considered to be representative sampling sites for long-term accumulations of attic dust. The mean values of the total U, Th and Cs (mg kg−1) concentrations as well as those of K (m/m %) in attic dust and urban soil samples are 2.4, 3.6, 1.7 and 0.6 and 1.1, 4.4, 1.2 and 0.3, respectively, measured using ICP-MS. The mean activity concentrations of 226Ra, 232Th, 40K and 137Cs in attic dust and urban soil samples are 43.3, 34.0, 534.4 and 88.5 and 25.1, 32.8, 386.4 and 5.6 Bq kg−1, respectively, by using a low-background iron chamber with a well-type HPGe and a n-type coaxial HPGe detector.The elemental compositions (U, Th) and activity concentrations (226Ra, 232Th) along with their abundances in coal ash from the CFPP increase in both studied media as the distance of the sampling sites from the CFPP decreases. Two outlier attic dust samples in particular show significantly high activity concentrations of 226Ra: 145 and 143, of 232Th: 83 and 94 Bq kg−1, which can be considered as a proxy of unweathered coal ash. The calculated total absorbed gamma dose rate (D) and annual effective dose (E) received from urban soils indicate that the presence of the CFPP, coal ash cone and slag dumps does not cause an increase in the level of background radiation in Salgótarján. However, the concentrations of the studied radionuclides are much higher (except for 232Th) and exhibit higher degree of variability in the samples of attic dustthan in those of urban soils. The study suggests that attic dust preserves the undisturbed ‘fingerprints’ of long-term atmospheric deposition thanks to its chemical and physical properties unlike urban soil.

210Pb Deposition Distribution in the Northern Hemisphere Based on a Long-Range Atmospheric Transport and Deposition Model Calculation

This study delves into the long-term atmospheric transport and deposition of 210Pb in the Northern Hemisphere by using the atmospheric transport model HIRAT. The calculation for the four-year (2012–2015) period showed an average deposition flux of 13.0 Bq m−2 month−1 with significant seasonal variations characterized by higher deposition rates during summer and lower during winter. High deposition was found in the Northern Bay of Bengal and Bangladesh regions, Southern China, the Western Philippine Sea, the Eastern Japan Sea, the Northwestern Pacific region, the Eastern and Western coasts of North America, the Caribbean Sea, the Eastern Pacific region off of Central America, the Central Atlantic region between Central America and Africa, and the Northwestern Atlantic Ocean. Deposition patterns varied across latitudinal zones, with tropical areas experiencing the highest deposition and polar/subpolar zones the lowest. This study emphasized the impact of monsoons on the significantly large 210Pb deposition in the Japan Sea region. Furthermore, this study showed that the lower troposphere (0 to 3 km) dominates with about 53%, and the middle troposphere (3 to 6 km) and upper troposphere (above 6 km) also contribute significantly to the total 210Pb inventory with 37% and 10%, respectively. These findings provide essential insights into the characteristics of atmospheric transport and deposition of 210Pb, and their mechanisms.

On the seasonality of long-range transport of acidic pollutants in East Asia

East Asia currently has the largest SO2 and NO x emissions in the world. The long-range transport (LRT) of acidic pollutants in this region is of great concern but the extent is not well understood. Here results from combined long-term (⩾20 years) atmospheric deposition monitoring and air trajectory analysis in East Asia were reported. The results showed that despite the large decrease of SO2 and NO x emissions in Taiwan, annual deposition of non-sea-salt sulfate (nss-) in northern Taiwan showed no decreasing trend during 1994–2020. However, when divided seasonally, both nss- and nitrate () deposition had a significant decreasing trend in the summer but not in the winter. Similar patterns were found for Japan and Korea. Air trajectory models in combination with a regional emission map indicate that LRT from eastern China contributed up to 70% of the winter deposition of nss- and in Taiwan and up to 50% in Japan and Korea. The results indicate that LRT obscured the efficacy of local pollution control measures in East Asia and suggest that transboundary air pollution regulations are required to combat acid deposition.

Global dispersal and potential sources of antibiotic resistance genes in atmospheric remote depositions.

Antibiotic resistance has become a major Global Health concern and a better understanding on the global spread mechanisms of antibiotic resistant bacteria (ARB) and intercontinental ARB exchange is needed. We measured atmospheric depositions of antibiotic resistance genes (ARGs) by quantitative (q)PCR in rain/snow collected fortnightly along 4 y. at a remote high mountain LTER (Long-Term Ecological Research) site located above the atmospheric boundary layer (free troposphere). Bacterial composition was characterized by 16S rRNA gene sequencing, and air mass provenances were determined by modelled back trajectories and rain/snow chemical composition. We hypothesize that the free troposphere may act as permanent reservoir and vector for ARB and ARGs global dispersal. We aimed to i) determine whether ARGs are long-range intercontinental and persistently dispersed through aerosols, ii) assess ARGs long-term atmospheric deposition dynamics in a remote high mountain area, and iii) unveil potential diffuse ARGs pollution sources. We showed that the ARGs sul1 (resistance to sulfonamides), tetO (resistance to tetracyclines), and intI1 (a proxy for horizontal gene transfer and anthropogenic pollution) were long-range and persistently dispersed in free troposphere aerosols. Major depositions of tetracyclines resistance matched with intensification of African dust outbreaks. Potential ARB mostly traced their origin back into agricultural soils. Our study unveils that air masses pathways are shaping ARGs intercontinental dispersal and global spread of antibiotic resistances, with potential predictability for interannual variability and remote deposition rates. Because climate regulates aerosolization and long-range air masses movement patterns, we call for a more careful evaluation of the connections between land use, climate change and ARB long-range intercontinental dispersal.

Chemical characterization of mountain forest soils: impact of long-term atmospheric deposition loadings (Czech-Polish-German border region).

The composition of lipids in soil offers clues to soil degradation processes due their persistency and selectivity in soil, and close relation to long-term processes in the ecosystem, thanks to their role in cell membranes of organisms. Organic solvent-extractable compounds were recovered from soils collected at two sites differing in the degree of forest damage. Gas chromatography/mass spectroscopy and Fourier transform infrared spectroscopy were applied in order to characterize solvent-extractable lipids. Raman spectroscopy was also applied as it provides distinct advantages for determining the structural order of carbonaceous materials. The organic matter measurement techniques were combined with an established simultaneous multi-element measurement technique. Variations in individual soil horizons from the sites were reflected in the crystallinity of epicuticular waxes, presence of long-chain aliphatic hydrocarbons, concentrations of n-alkanes, saturated and unsaturated fatty acids, dicarboxylic acids, and in the content of aromatic structures, hydroxyl, ester, and carboxylic acid groups. The results are explained by differently transformed organic matter. The concentrations of elements in the soils were also affected by atmospheric depositions, including higher accumulations of arsenic and antimony, and lower contents of natural nutrients. These data have potential to be used as sensitive biogenic indicators of ecosystem damage by long-term atmospheric depositions.

Projections of long-term human multimedia exposure to metal(loid)s and the health risks derived from atmospheric deposition: A case study in the Pearl River Delta region, South China

This is one of a limited number of studies that investigates multimedia exposure to metal(loid)s and the related human health risks caused by atmospheric deposition in China and Asia. The aggregate multimedia human exposure included the accidental ingestion and dermal adsorption of soil and surface water, as well as the intake of grains, fruits, vegetables, meats and eggs, milk and dairy products, and freshwater fish. The values and variabilities of atmospheric deposition and exposure factors were identified as two major uncertainty sources. The annual variations in wet and bulk deposition were propagated from the variabilities of particulate matter (PM) × precipitation and the linear regressed coefficients of flux~PM × precipitation, and the annual variation in dry deposition was propagated by subtracting the wet deposition from the bulk deposition. The variabilities in the exposure factors were updated based on the latest published regional data. Long-term atmospheric deposition was identified as a vital source of Cd contamination in surface soil and freshwater bodies and As accumulation in freshwater fish. The noncarcinogenic (NC) risk probabilities caused by Cd were the highest, followed by As. The overall uncertainties related to the NC risk probabilities were much lower for both adults and 6- to 17-year-old children/adolescents, while those related to the carcinogenic risk (CR) probabilities were much lower for 2- to 5-year-old children and 6- to 17-year-old children/adolescents. Our results could help infer the cobenefits due to the current regional air pollution control policy.

A first record of bulk atmospheric deposition patterns of major ions in southern South America

Despite the importance of long-term atmospheric deposition of ions for vegetation productivity and biogeochemistry, southern South America lacks long-term deposition records. We report a 6-year-long record of atmospheric deposition measurements of Mg2+, Ca2+, Na+, K+, Cl−, SO42−, NO3− and NH4+ in the plains of southern South America, which encompass one of the most important agricultural basins and urban clusters of the continent. After establishing a deposition measurement network across four sites in Argentina and Uruguay, we collected bulk atmospheric deposition monthly form January 2007 through December 2012 in an east–west transect of 700 km. Spatial changes in the sea-salt component of atmospheric deposition were primarily associated with proximity to the sea—as observed in other regions of the world—whereas non-sea-salt components of atmospheric deposition of terrestrial origin were primarily associated with the size of the human population surrounding collection sites. Atmospheric deposition showed a strong interannual variability (CV 50%) mainly associated with variations in the non-sea salt components of terrestrial origin and were within observed values for other relatively unpolluted sites of South America and globally. However, atmospheric deposition appears to be increasing in the region, particularly for SO42− and other ions around Buenos Aires, Argentina, which may represent an early warning of increased air pollution in the area. Average annual regional deposition of sulfate (SO42−) was 12.7 kg S hectare−1 and nitrate (NO3−) was 9.2 kg N hectare−1. Weighted average concentrations of base cations (sum of Mg2+, Ca2+, Na+ and K+) was 0.27 mg L−1, and weighted average concentrations of SO42−, NO3− and NH4+ were 0.094, 0.018 and 0.046 mg L−1, respectively. Our work highlights the need for long-term networks recording atmospheric deposition in the region, increasing knowledge of nutrient cycling and establishing a baseline for future atmospheric pollution measurements.

Mercury and metal(loid) deposition to remote Nova Scotia lakes from both local and distant sources

Kejimkujik National Park, in Nova Scotia, Canada, is a sensitive region for metal(loid) contamination, such as mercury, in part due to long-range atmospheric deposition from global and regional industrial centers. The region is remote from industrial centres, but is downwind of major pollution sources in the Eastern United States and Canada, and historically had numerous gold mining sites. Due to a paucity of long-term atmospheric deposition monitoring in this region, little is known about the response of Kejimkujik lakes to multiple changing global, regional and local atmospheric Hg and metal(loid) sources. Here, we used multiple lake sediment cores to reconstruct anthropogenic depositional fluxes of metal(loid)s of concern for the last ~210years. Results showed that Kejimkujik lake sediments are highly enriched in lead (Pb), antimony (Sb) and tin (Sn), with post-industrial metal(loid) concentrations being >4-fold greater than natural baseline levels (prior to ~1800) and moderately enriched in silver (Ag), bismuth (Bi), cadmium (Cd), copper (Cu), mercury (Hg), rubidium (Rb), tellurium (Te), thallium (Tl), vanadium (V), tungsten (W) and zinc (Zn), with post-industrial metal(loid) concentrations being between 1.5 and 4-fold greater than natural baseline levels (prior to ~1800). Lake sediment core reconstructions of total atmospheric Hg deposition matched well with Hg wet deposition monitoring data from the overlapped period (1997–2010) being 9.1±2.7μg/m2/yr and 7.0±0.7μg/m2/yr respectively. Lakes closest to historic gold mining sites show spikes in Ag, Cd, Sb, Tl, Zn and W during mining periods (~1880 and 1950). Most of the enriched metal(loid)s (EF >1.5) (Ag, Bi, Cu, Hg, Pb, Sb, Sn, V and W) do not appear affected by redox and remobilisation issues. For the other enriched metal(loid)s (EF >1.5) (Cd, Tl, and Zn), remobilisation from upper sediments appears to be occurring within these acidic and DOC rich Kejimkujik lakes.

Anthropogenic and lithogenic fluxes of atmospheric lead deposition over the past 3600 years from a peat bog, Changbai Mountains, China

Ombrotrophic peatlands are widely used to reconstruct atmospheric metal deposition histories. Here, we estimated the long-term atmospheric Pb deposition flux using ombrotrophic peatland data from the Changbai Mountains, northeast China. A peat profile of 320-cm depth was sampled and cut into 164 slices for measurement of Pb and other elements by ICP-MS and ICP-AES and radiometric dating by 210Pb, 137Cs and 14C. Pb concentration in the peat ranged from 2.18 to 68.33 mg kg−1, while the atmospheric Pb deposition flux ranged from 0.12 to 12.49 mg m−2 a−1. The Little Ice Age (cold and wet climate) led to low Pb concentration, Pb/Sc ratio, and Pb deposition flux (4.40 ± 0.70 mg kg−1, 2.04 ± 0.38, and 0.28 ± 0.09 mg m−2 a−1, respectively). On the other hand, intense volcanic eruptions resulted in high Pb concentration, Pb/Sc ratio, and P flux (54.48 ± 13.08 mg kg−1, 7.85 ± 2.09, and 8.15 ± 2.85 mg m−2 a−1, respectively). In addition, rapid economic development since the 1980s resulted in a gradual increase of anthropogenic Pb concentration from 1.54 mg kg−1 to 5.85 mg kg−1; thus, the anthropogenic Pb deposition flux (0.43 ± 0.21 mg m−2 a−1) was high during this period. In general, peat Pb concentration and atmospheric Pb deposition fluxes in this region have been affected by climate change, volcanic eruptions, and human activities. It was further demonstrated that atmospheric Pb emissions and deposition in China decreased since leaded gasoline was phased out in 2001. The results are critical to understand the geochemistry of Pb and to assess the effects of human activities on atmospheric Pb emissions and deposition in China.

Calcium and magnesium biogeochemistry in spruce catchments underlain by felsic, mafic, and ultramafic rocks

Three small forested catchments in the Czech Republic, each underlain by chemically contrasting silicate rocks, were investigated with focus on long-term atmospheric deposition of S, and pools and fluxes of Ca and Mg. Pools of Ca and Mg reflected geological substrate (granite: Ca, Mg poor, amphibolite: Ca, Mg rich, serpentinite: Ca poor, Mg rich). Long-term fluxes of S, Ca and Mg were tightly connected.

Humus samples as an indicator of long-term anthropogenic input – A case study from southern Finland

Humus has been recognized as one of the best sampling media for mapping regional environmental contamination. However, because of the complex and incompletely understood geochemistry of humus, reflecting to differing extents the underlying geology, the biospheric activity, and airborne deposition, its application is still not widespread.This study was conducted within the framework of a comparison between regional humus and topsoil geochemical baseline data in order to analyze the element concentrations in humus and to find possible associations with the underlying geology and long-term atmospheric deposition. The analyzed samples formed part of a geochemical mapping program carried out by the Geological Survey of Finland (GTK) from 2002, and humus samples collected over an area of 37,000km2 in southwestern Finland are elaborated here for the first time. Altogether, 816 sample pairs (humus and topsoil samples) were selected for statistical analysis and analysis of correlations between the element concentrations in humus and minerogenic topsoil and between the element and organic carbon contents.Statistical graphs constructed for 31 elements revealed that most of the elements have a completely different distribution of concentrations in humus and topsoil samples. The concentrations of some elements in humus, such as K, Mg, Fe, and Al, are controlled by the content of mineral matter, which is derived from soil dust (<0.002mm). Other elements, such as As, Bi, Cd, Co, Cu, Mo, Ni, Pb, Rb, Th, V, and Zn, showed evident outliers in humus samples with a probable anthropogenic origin. In order to explain these anomalous high values in humus, the geographic distributions of these elements in humus and topsoil were analyzed and then compared with deposition data obtained from national moss surveys.According to the results presented here, the humus element concentrations are more strongly affected by atmospheric inputs than by the lithogenic contribution, which is opposite to the case for the topsoil samples. The topsoil element distribution maps clearly show a strong relationship with the bedrock geology, such as the relationship of the Ni distribution with the Ni-Co-Cu metallogenic area of the Tampere Region, while the element distributions in humus show a strong correlation with the anthropogenic impact of known deposition from local pollution sources. No long-range transport was clearly identified, but point sources, such as the Pori-Harjavalta smelters, and more densely populated and industrialized areas, such as the city of Tampere and the coastline from the city of Porvoo to the capital region of Helsinki, cause locally high anomalies in humus concentrations, even many years after the reduction of industrial inputs. Further humus samples should be collected with a sufficient sampling density close to city centers and industrialized areas in order to improve knowledge of element concentrations in humus and anthropogenic inputs to the topmost layer of the ground surface, as well as potential risks to the environment and human health.

Long-term atmospheric deposition of nitrogen, phosphorus and sulfate in a large oligotrophic lake.

We documented significantly increasing trends in atmospheric loading of ammonium (NH4) and nitrate/nitrite (NO2/3) and decreasing trends in total phosphorus (P) and sulfate (SO4) to Flathead Lake, Montana, from 1985 to 2004. Atmospheric loading of NO2/3 and NH4 increased by 48 and 198% and total P and SO4 decreased by 135 and 39%. The molar ratio of TN:TP also increased significantly. Severe air inversions occurred periodically year-round and increased the potential for substantial nutrient loading from even small local sources. Correlations between our loading data and various measures of air quality in the basin (e.g., particulate matter <10 µm in size, aerosol fine soil mass, aerosol nutrient species, aerosol index, hectares burned) suggest that dust and smoke are important sources. Ammonium was the primary form of N in atmospheric deposition, whereas NO3 was the primary N form in tributary inputs. Atmospheric loading of NH4 to Flathead Lake averaged 44% of the total load and on some years exceeded tributary loading. Primary productivity in the lake is colimited by both N and P most of the year; and in years of high atmospheric loading of inorganic N, deposition may account for up to 6.9% of carbon converted to biomass.

Long-term atmospheric wet deposition of dissolved organic nitrogen in a typical red-soil agro-ecosystem, Southeastern China

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 (P<0.0001) suggested that agricultural activities, especially application of pig manure, were the main source of DON in the study area. In conclusion, DON wet deposition was an important part of TDN and would have a possible effect on N cycle in the red-soil agro-ecosystem in the future.

Nitrogen and carbon contents and δ15N and δ13C signatures in six bryophyte species: assessment of long‐term deposition changes (1980–2010) in Spanish beech forests

In this study we used recent (2010) and herbarium material (1980) of six bryophyte species to assess long-term atmospheric deposition in natural forested areas in northern Spain. For this purpose, tissue nitrogen and carbon content, as well as δ(13) C and δ(15) N signatures of samples of Hypnum cupressiforme, Polytrichastrum formosum, Leucobryum juniperoideum, Rhytidiadelphus loreus, Homalothecium lutescens and Diplophyllum albicans were analysed and comparisons made between years and species. In addition, the usefulness of each of the six species was evaluated. The range of values observed was similar to that in other studies carried out in rural areas. Significantly lower values were found in 2010 for N (H. cupressiforme), δ(15) N (R. loreus and D. albicans), C (R. loreus) and δ(13) C (all except L. juniperoideum). Our natural areas are thus now less influenced by atmospheric pollutants than they were, most probably due to changes in some traditional local activities. Differences were observed between species for all the four parameters studied, so different species must not be analysed together. Finally, R. loreus and H. lutescens seem to be good bioindicators, sensitive even with a few samples, although further studies are needed to corroborate their usefulness.

Anthropogenic metal contamination and sapropel imprints in deep Mediterranean sediments

Sediment cores from the deep Balearic basin and the Cretan Sea provide evidence for the accumulation of Cd, Pd and Zn in the top few centimeters of the abyssal Mediterranean sea-bottom. In both cores, 206Pb/207Pb profiles confirm this anthropogenic impact with less radiogenic imprints toward surface sediments. The similarity between excess 210Pb accumulated in the top core and the 210Pb flux suggests that top core metal inventories reasonably reflect long-term atmospheric deposition to the open Mediterranean. Pb inventory in the western core for the past 100years represents 20–30% of sediment coastal inventories, suggesting that long-term atmospheric deposition determined from coastal areas has to be used cautiously for mass balance calculations in the open Mediterranean. In the deeper section of both cores, Al normalized trace metal profiles suggest diagenetic remobilization of Fe, Mn, Cu and, to a lesser extent, Pb that likely corresponds to sapropel event S1.

Which processes prevail?: Analyzing long-term soil solution monitoring data using nonlinear statistics

Soil monitoring yields large and heterogeneous data sets. To identify the prevailing processes as well as identifying spatial patterns or temporal trends, mostly linear approaches are used. Here, a nonlinear approach, Isometric Feature Mapping (Isomap), was applied and compared to the established linear Principal Component Analysis (PCA) to a data set from a long-term monitoring program in the forested Lehstenbach catchment (Fichtelgebirge, Germany). The data set comprised more than 4000 soil solution samples from different periods, soil types and varying depths, where 16 solutes were determined. The nonlinear Isomap approach achieved slightly better results than the linear procedure. More than 94% of the variance of the given data set was explained by the first five components. About 46% of the variance was ascribed to the impact of long-term atmospheric deposition. Soil acidification may explain the characteristics of the second component and another 28% of the data set's variance. The third component indicated a long-term shift of deposition chemistry that accounted for nearly 13% of the variance. Matrix–solution interactions and decomposition of organic matter were ascribed to the fourth and fifth component, explaining another 5.8% and 1.6% of the variance of the data set. Thus, long-term deposition could be interpreted as the most important factor influencing soil solution chemistry in different ways. Based on the Isomap results spatial and temporal patterns were investigated. Different redox conditions and depth of sampling accounted for much of the spatial variance. The identified components differed substantially with respect to seasonal patterns or long-term trends. The nonlinear Isomap approach revealed applicability and further potential for analyzing comprehensive data sets in soil science.

Determination of heavy metal deposition in the county of Obrenovac (Serbia) using mosses as bioindicators, IV: Manganese (Mn), Molybdenum (Mo), and Nickel (Ni)

In this study, the deposition of three heavy metals (Mn, Mo, and Ni) in the county of Obrenovac (Serbia) in four moss taxa (Bryum argenteum, Bryum capillare, Brachythecium sp., and Hypnum cupressiforme) is presented. The distribution of average heavy metal content in all mosses in the county of Obrenovac is presented on maps, while the 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 tabular form. Areas of the highest contaminations are highlighted.

Estimation of potential impact on Copenhagen, Denmark due to accidental releases at Nuclear Risk Sites

This paper is focused on the testing of a methodology developed for nuclear risk and vulnerability assessment, and probabilistic evaluation of the long-term atmospheric transport and deposition patterns for radioactive pollutants from selected nuclear risk sites in the Euro-Arctic region. A combination of models (3-D trajectory, DERMA, and HIRLAM) was used to simulate such transport, dispersion, and deposition of 137Cs for a one-day hypothetical release. The ranking of the potential impact on Copenhagen, Denmark from selected sites showed that for concentration and dry deposition the order of such ranking is identical. If wet deposition is accounted for, the ranks can change significantly at the mesoscale.

Long-term atmospheric deposition of current-use and banned pesticides in Atlantic Canada; 1980–2000

The occurrence of current-use and banned pesticides is reported in wet-precipitation collected from four sites across Atlantic Canada during the period 1980–2000. The most frequently detected compounds were α-HCH, γ-HCH (lindane), chlorothalonil, pentachlorophenol, atrazine, and endosulfan. Median site concentrations varied between not-detected and 10.2 ng l −1. Deposition of HCHs (hexachlorocyclohexane), chlorothalonil, and endosulfan at Kejimkujik (Keji) and Jackson, Nova Scotia, were generally similar. Significant spatial differences ( p < 0.05), however, were found for the HCH isomers and endosulfan at Keji and Gros Morne (Newfoundland and Labrador), areas geographically separated by the northern Gulf of St. Lawrence. Long-term deposition of α-HCH decreased ( p < 0.05) at both Keji (1980–2000) and Gros Morne (1994–2000), with half-lives of 5.9 and 4.5 y, respectively. A decreasing trend was also found for pentachlorophenol with a half-life of 4.9 y at Jackson. Significant negative trends ( p < 0.05) were observed for α-/γ-HCH ratios during the study at Keji and Jackson, possibly reflecting changes in production and use patterns of technical HCH and lindane on a continental and perhaps hemispheric scale. Seasonal trends for α-HCH and γ-HCH were found to vary over the 20-y study period at Keji, however, spatial trends were generally similar between sites. Seasonal trends were observed with peak deposition generally occurring during the growing period (spring-summer) for the HCHs, chlorothalonil, endosulfan, and atrazine. Bimodal seasonal trends were also observed for these compounds with the exception of endosulfan.