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Among environment contaminants, 210Pb and 210Po have gained significant research attention due to their radioactive toxicity. Moss, with its exceptional adsorption capability for these radionuclides, serves as an indicator for environmental 210Pb and 210Po pollution. The paper reviews a total of 138 articles, summarizing the common methods and analytical results of 210Pb and 210Po research in moss. It elucidates the accumulation characteristics of 210Pb and 210Po in moss, discusses current research challenges, potential solutions, and future prospects in this field. Existing literature indicates limitations in common measurement techniques for 210Pb and 210Po in moss, characterized by high detection limits or lengthy sample processing. The concentration of 210Pb and 210Po within moss display substantial variations across different regions worldwide, ranging from

Monitoring and mapping of atmospheric deposition can be achieved by use of chemical transport models, technical sampling devices and/or bio-accumulators such as mosses, lichens, etc. Within the European Moss Survey programme, since 1990 every 5 years mos specimens have been collected and analysed for heavy metals, nitrogen and persistent organic pollutants according a harmonised methodology. Calculation and geostatistical mapping of percentile statistics of element concentration in moss is in the focus of this paper. Thereby, element- and survey-specific as well as heavy metals and surveys integrating statistical evaluations and GIS-mapping were performed. Cr, Sb and Zn show contrary to Fe and Pb, no constant decrease of element concentrations, but an intermediate increase between 2000 and 2005, which did not continue until 2015. Cd, Hg, Pb and N which are of priority according to the Convention on Long-Range Transboundary Air Pollution are in focus in this paper. Additionally, Cr is regarded as representing those elements with an intermediate increase between the years 2000 and 2005 as is also true for Sb and Zn. Surveys integrating percentile statistics depict the spatial patterns of, in most cases, declining element concentrations across time. Survey-specific statistical analyses corroborate that the spatial patterns of element concentrations in moss are changing element-specifically across time. The long-term information on the percentile statistics of bioaccumulation of atmospheric deposition in moss is essential for further scientific evaluation as well as for measurements and reporting of nature protection and environmental management. [ABSTRACT FROM AUTHOR]

The rising trend of plastic production in last years and the inadequate disposal of related waste has raised concerns regarding microplastic-related environmental issues. Microplastic particles disperse by means of transport and deposition processes to different ecosystems and enter food chains. In this paper, atmospheric deposition and foliage samples of two species (i.e. , Hedera helix and Photinia glabra) were collected and analysed for the quantity and identity of microplastics (MPs). A preliminary methodology to treat foliage samples and subsequently identify MPs using a quantum cascade laser IR spectrophotometer is presented. The treatment of airborne samples involved filtration, mild digestion, concentration, and transfer onto reflective slides whereas that for foliage involved washing, concentration, and transference of putative MPs onto reflective slides. Fibers and fragments were differentiated according to their physical features (size, width, height, etc.) and calculating derived characteristics (namely, circularity and solidity). The preliminary results obtained suggest a good agreement between atmospheric-deposited and foliage-retained MPs, showing the capability of leaves to act as passive samplers for environmental monitoring. [Display omitted] • Leaves can be used as a passive air sampler for microplastics. • Fragments and fibres can be found over leaf surface. • Fibres of 100–500 μm and fragments of 20–50 μm predominate. • PET, PP, PE, PVC, and PP were detected most frequently in air and on leaves. • Concentrations in leaves and air agree although more comparative data are needed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Bulk-sample Nd isotopes can be used to trace sedimentary provenances of silicate components in deep-sea sediments. • Elements are classified into lithophile-, phosphate- and metal-oxide elements. • Accumulated biophosphate enriches phosphophilic REY released by dissolved silicates during early diagenesis. Deep-sea sediments have become an important new type of rare-earth element (REY) resources that have high potential to meet the increasing demand. However, the enrichment mechanisms of such deposits remain unclear. In this paper, we made a detailed discussion in bulk-sample geochemistry along the core profile of GC26 collected at the western Pacific Ocean. Elements are classified into lithophile-, phosphate-, and metal oxide elements, which have affinities to silicate, phosphate, and Fe–Mn (oxyhydr)oxide phases in sediments, respectively. Biophosphate is the major host of REY in deep-sea sediments. Its accumulation has a substantial effect on bulk-sample strontium isotopes, but a weak effect on bulk neodymium isotopes. Although the bulk neodymium isotopes imply there was a slight change in sedimentary provenances, it cannot explain the different behaviors of the three elemental groups simultaneously. Water-rock interactions at high temperature enlighten us that water–sediment interactions at low temperature, also known as early diagenesis, may be the answer of behaviors of the three element groups. Silicate dissolution during early diagenesis releases elements from the silicate lattice. When biophosphate accumulation occurs, the released phosphate elements (including REY) are preferentially incorporated into biophosphate rather than being released into seawater, which is the key to REY enrichment in deep-sea sediments. This is also the case for metal oxide elements (e.g., Mn, Co, and Ni) when oxygen fugacity is high enough to cause Fe–Mn (oxyhydr)oxide deposition as coatings or micro-nodules. Considerable amounts of silicate elements (e.g., Al, Ti, Fe, Cr, and V) are released into seawater to participate into global oceanic element cycle if they are less compatible in newly formed secondary silicate components (e.g., phillipsite). Our results provide new insights into the importance of early diagenesis of deep-sea sediments to REY enrichment and the global oceanic elemental budget. [ABSTRACT FROM AUTHOR]

In this study, dry deposition samples were collected with both an aerodynamically smooth water surface (WSS) and a knife-edge surrogate surface (KSS) in Potsdam, NY, Solomons, MD, and at a farm in upstate NY intermittently between March 2000 and August 2001. The WSS and the citric acid-coated paper filter on the KSS were used to measure total ammonium deposition (NH3 and p-NH4+), while a greased Mylar disk on the KSS was used to measure particulate NH4+ (p-NH4+) deposition. An annular denuder system (ADS) was used to measure NH3 gas phase and particulate NH4+ concentrations. In side-by-side experiments with two WSSs, no statistical difference was found between simultaneously measured total ammonium deposition at any of the sites. Average total NH3 fluxes measured with the WSS in Potsdam, Solomons, and at the farm were 3.1, 2.1, and 310 mg NH4+ m−2 day−1, respectively. Similarly gaseous NH3 fluxes measured with the citric acid-coated paper on the KSS were 3.6, 2.1, and 500 mg NH4+m−2 day−1, respectively. The p-NH4+ fluxes to the KSS-greased strip were negligible at all three locations. Fluxes measured by the citric acid paper filters were slightly greater than those measured with the WSS suggesting that the acidic dry surfaces had a higher affinity for ammonia than the water in the WSS.The average gas-phase ammonia concentrations in Potsdam, Solomons, MD and at the farm were 0.60×10−3, 2.1×10−3, and 0.25 mg NH4+ m−3, respectively. The average ammonium concentrations were 0.50×10−3, 1.2×10−3, and 14×10−3 mg NH4+ m−3, respectively. [Copyright &y& Elsevier]

In a publication in Atmospheric Environment ( http://dx.doi.org/10.1016/j.atmosenv.2015.10.081 ), Gu et al. (2015) estimated that “the total nitrogen (N) deposition in 2010 was 2.32 g N m −2 yr −1 ” in China. This value is comparable with previous estimations based on a synthesized dataset of wet/bulk inorganic N deposition observations, which underestimates the total N deposition since their algorithm (equations (2) and (3) in their paper) does not account for dry deposition of NH 3 , HNO 3 , NO x and wet/dry deposition of HONO and organic nitrogen (e.g. amines, amides, PAN). Indeed, Gu et al. (2015) mixed the terminology of wet/bulk deposition and total deposition. Another flawed assumption by Gu et al. (2015) is that all inorganic N in precipitation estimated by their algorithm originates from fertilizer and coal combustion. This is incorrect and almost certainly causes biases in the spatial and temporal distribution of estimated wet/bulk inorganic N deposition (Fig. 5 in their paper), further considering the fact that they neglected important N sources like livestock and they did not consider the nonlinearity between various sources and deposition. Besides the input data on N deposition, the model validation (Sect. 2.3.2) described in their paper also requires clarification because the detailed validation information about the time series of observational dataset versus modeling results was not given. As a result of these combined uncertainties in their estimation of N deposition and the lack of detail for model-measurement comparison, their estimates of the impacts of N deposition on carbon storage in Chinese forests may need further improvement. We suggest the clarification of the terminology regarding N deposition, especially for wet deposition, bulk deposition, gaseous and particulate dry deposition or total deposition since the accurate distinction between these terms is crucial to investigating and estimating the effects of N deposition on ecosystems. [ABSTRACT FROM AUTHOR]

South Africa is the economic hub of southern Africa and is regarded as an important source region of atmospheric pollutants. A nitrogen dioxide (NO 2 ) hotspot is clearly visible from space over the South African Mpumalanga Highveld, while South Africa is also regarded as the 9th largest anthropogenic sulphur (S) emitting country. Notwithstanding the importance of South Africa with regard to nitrogen (N) and S emissions, very limited data has been published on the chemical composition of wet deposition for this region. This paper presents the concentrations of sodium (Na + ), ammonium (NH 4 + ), potassium (K + ), calcium (Ca 2+ ), magnesium (Mg 2+ ), nitrate (NO 3 − ), chloride (Cl − ), sulphate (SO 4 2− ) and water-soluble organic acids (OA) in the wet deposition samples collected between 2009 and 2014 at four South African IDAF (IGAC DEBITS Africa) sites, which are regarded as regional representatives of the north-eastern interior. Also, wet deposition fluxes of the ten ions are calculated and presented in this paper. The results show that the total ionic concentrations and fluxes of wet deposition were much higher at the two sites closer to anthropogenic emissions, while the pH of wet deposition at these two sites were lower compared to that of the two sites that were less impacted by anthropogenic emissions. . The major sources of the ten ions included marine, terrigenous (crust), fossil fuel combustion, agriculture and biomass burning. Significant contributions from fossil fuel combustion were determined for the two sites in close proximity to anthropogenic source regions. The results of back trajectory analysis, however, did indicate that the two remote sites are also affected by air masses passing over the source region through anti-cyclonic recirculation. The largest contributions at the two sites distant from the anthropogenic source regions were marine sources, while the impact of biomass burning was also more significant at the remote sites. Comparison to previous wet deposition measurements at the South African IDAF sites indicated increases in the wet deposition fluxes of S and N, and more wet deposition events with lower pH. This could be ascribed to a significant increase in anthropogenic activities and population growth in this part of South Africa with an associated increase in energy demand. [ABSTRACT FROM AUTHOR]

Deposition of pollutants by cloud water exceeds deposition by precipitation and dry deposition in many high elevation settings. This larger loading of pollutants in these environments is due to a combination of factors such as high frequency of cloud immersion, high wind speeds, orographic enhancement of precipitation, and large leaf area of tree species typical in these environments. Fog-impacted coastal ecosystems also experience increased pollutant deposition similar to cloud-impacted high elevation sites. Therefore, development of meaningful critical load values and total nitrogen budgets for high-elevation and fog-impacted sites requires reliable cloud and fog water deposition estimates. The cost and labor intensity of cloud/fog water sample collection have made it difficult to conduct long-term studies that would provide the data needed to develop accurate estimates. Current understanding of fog formation, transport, and the role of fog and cloud deposition in hydrogeological and biogeochemical cycles is incomplete due, in part, to lack of a concerted interdisciplinary approach to the problem. Historically, these obstacles have limited interest in and collection of cloud and fog water samples. In addition to measurements of cloud/fog chemical composition, documenting fog/cloud deposition fluxes of pollutant and nutrient species requires knowledge of cloud/fog physical properties, frequency and duration of fog/cloud interception with landscapes, properties of vegetation on those landscapes, and properties of the wind that drive droplet/vegetation interactions. Because drop deposition efficiency is dependent on drop size, it is also important to consider variations in fog/cloud drop composition with drop size as species enriched in larger/smaller drops will experience enhanced/reduced deposition rates. This paper presents summary results from a small U.S. cloud water monitoring network that operated from the mid-nineties through 2011, as well as a brief qualitative review of other cloud and fog water studies conducted in the United States (including Puerto Rico), Europe, South America/Pacific, and Asia. Current collection methods are also reviewed. Recent scientific efforts by the National Atmospheric Deposition Program's (NADP) Total Deposition Science Committee and NADP's Critical Loads of Atmospheric Deposition Science Committee have identified occult (cloud/fog) deposition as a "need" in developing critical loads for ecosystems that experience significant cloud and fog impaction. To this end, remaining knowledge gaps and suggestions for future research to investigate these gaps are explored. • At elevations above 800m cloud water samples are usually 5–20 times more acidic than rainwater. • Impacts of N deposition on alpine/subalpine regions are numerous and substantial. • Deposition loads of 10–40 kg N/ha/year in high-elevation areas in the eastern US are much higher than in the west. • Productivity and species shifts may have already occurred in eastern alpine ecosystems. • This paper is a qualitative summary of existing knowledge on cloud/fog water deposition. [ABSTRACT FROM AUTHOR]

Sixty rainwater samples were collected covering four seasons from July 2020 to April 2021 from the center of Chongqing, a metropolitan city of southwest China, using automatic deposition sampler. The samples were analysed for 17 targeted poly- and per-fluoroalkyl substances (PFASs) by HPLC-MS/MS. The concentration of PFASs ranged from 3.31 ng/L to 196.14 ng/L and dominated by perfluoro-n-octanoic acid (PFOA), perfluoro-n-hexanoic acid (PFHxA), perfluoro-n-butanoic acid (PFBA) and sodium perfluoro-1-octanesulfonate (PFOS). The seasonal variations of dissolved and particulate PFAS were distinct, with the highest level in summer and autumn, respectively. Positive matrix factorization (PMF) and a wet deposition model were performed to apportion the sources and estimate the wet deposition flux of the 17 PFASs, respectively. PMF analysis indicated that, based on yearly average, paper packaging production (37.4%) and aqueous film forming foam (AFFF) usage (29.8%) were the two major sources, followed by textile production (16.7%) and electronic product manufacturing (16.1%). The highest source contributor for PFASs in winter was AFFF usage (47.0%); while in the other three seasons, it was paper packaging production that contributed the most (50.1%, 39.8% and 34.8% respectively). Seasonal average wet deposition flux of PFASs was estimated to be 13.9 ng/m2/day. The dry deposition of PFASs was estimated to account for 15.8% of the total atmospheric deposition flux, suggesting a more important role for wet deposition. The results of this study provide important information for understanding of PFASs occurrence and atmospheric wet deposition in Chongqing, and other urban centers across China. [Display omitted] • The dissolved and particulate PFASs in rainwater was 20.3 ng/L and 4.39 ng/L, respectively. • PMF identified paper packaging production was the major sources. • The average wet deposition flux of PFASs was estimated as 13.9 ng/m2/day. [ABSTRACT FROM AUTHOR]

The Laurentian Great Lakes region of North America contains substantial aquatic resources and mercury-contaminated landscapes, fish, and wildlife. This special issue emanated from a bi-national synthesis of data from monitoring programs and case studies of mercury in the region, here defined as including the Great Lakes, the eight U.S. states bordering the Great Lakes, the province of Ontario, and Lake Champlain. We provide a retrospective overview of the regional mercury problem and summarize new findings from the synthesis papers and case studies that follow. Papers in this issue examine the chronology of mercury accumulation in lakes, the importance of wet and dry atmospheric deposition and evasion to regional mercury budgets, the influence of land–water linkages on mercury contamination of surface waters, the bioaccumulation of methylmercury in aquatic foods webs; and ecological and health risks associated with methylmercury in a regionally important prey fish. [Copyright &y& Elsevier]

Abstract In the framework of the INDAAF (International Network to study Deposition and Atmospheric chemistry in AFrica) programme, part of the ACTRIS European Research Infrastructure for the long-term observation of Aerosols, Cloud, and Trace gases, this paper aims to study trends and seasonal variability of surface atmospheric NO 2 and HNO 3 concentrations, and OMI (Ozone Monitoring Instrument) NO 2 over 6 sites in tropical Africa. Sites are located in west and central Africa to represent the major African biomes: dry savanna (Banizoumbou, Niger and Katibougou, Mali), wet savanna (Djougou, Benin and Lamto, Côte d'Ivoire) and forest (Bomassa, Republic of Congo and Zoétélé, Cameroon). Ground-based NO 2 and HNO 3 concentrations were obtained over the period 1998–2015 using INDAAF passive samplers at a monthly basis, and NO 2 Vertical Column Densities (VCDs) from OMI for a 1° grid cell around each sites were obtained from 2005 to 2015. Mean annual NO 2 concentrations ranged from 2.3 ± 1.2 to 0.9 ± 0.4 ppb from dry savannas to forests, representing a north south gradient. In dry savannas, we observe two concentration peaks of NO 2 appearing at the beginning and the end of the wet season both for ground-based and satellite measurements, whereas at wet savannas and forest sites, NO 2 concentrations are highest in the dry season. The seasonality of surface NO 2 observations provide further evidence for a large role of microbial soil NOx emissions in dry savannas and of biomass burning NOx emissions in wet savanna and forest sites. Mean annual HNO 3 concentrations ranged from 0.4 to 0.5 ppb in dry and wet savannas to 0.2–0.3 ppb in forest. In dry ecosystems, higher HNO 3 concentrations are measured in the early wet season, consistent with NO 2 results. The analysis of a long-term dataset of surface O 3 concentrations indicates that HNO 3 production can mainly be explained by the photooxidation of NO x. Mann-Kendall and Seasonal Kendall statistical tests showed that NO 2 surface concentrations have a significant decreasing seasonal and annual trends at multiple sites (p-value < 0.05) ranging from −2.96% yr−1 (at Zoétélé) to −0.64% yr−1 (at Banizoumbou). HNO 3 results indicate no trends except at Bomassa (1.07% yr−1). The decreasing NO 2 ground-based concentration trends observed in wet savannas sites are correlated with OMI NO 2 decreasing trends at these sites. Trends obtained for NO 2 concentrations in wet savanna and forest ecosystems are consistent with trends of NOₓ biomass burning emissions. Highlights • Long term data of surface and column nitrogenous gases from major African biomes. • North-South latitudinal negative gradient in surface concentrations of NO 2 and HNO 3. • Microbial soil emissions of NOₓ are predominant in dry savannas. • Biomass burning emissions of NOx are predominant in wet savanna and forest sites. • NO 2 annual and seasonal decreasing trends at most of west and central Africa sites. [ABSTRACT FROM AUTHOR]

Abstract The Great Lakes Region of the US continues experiencing exceedances of the ozone (O 3) standards, despite years of emissions controls. In part, this is due to interactions between emissions from surrounding large cities (e.g., Chicago) and meteorology, which is heavily influenced by the presence of the Great Lakes. These complex meteorology-emissions interactions pose a challenge to fully capture O 3 dynamics, particularly near shores of the lakes, where high O 3 levels are often experienced. In a simulation with the Community Multiscale Air Quality (CMAQ) model, using inputs as typically constructed, the model tends to be biased high. A literature review indicated that NO x emissions from mobile sources, possibly overestimated in the 2011 National Emission Inventory (NEI), or the version of the Carbon Bond chemical mechanism used in CMAQ could be responsible for high biases of O 3. As such, a series of sensitivity tests was conducted to identify potential causes for this bias, including emissions biases (e.g., biogenic VOCs, anthropogenic NO x), chemical mechanism choice, and O 3 dry deposition to fresh water, for high O 3 periods in July 2011. The base model/emissions configuration used the following: Carbon Bond mechanism CB05, biogenic emissions using Biogenic Emission Inventory System (BEIS), and anthropogenic emissions from the 2011 National Emissions Inventory (NEI). Meteorological inputs were developed using the Weather Research and Forecasting (WRF) model (version 3.8.1). Simulated daily maximum 8-h average O 3 without and with a cutoff of 60 ppb (referred to as MDA8 O 3 and elevated MDA8 O 3 hereafter, respectively) were evaluated against measurements. The evaluation showed a high bias in MDA8 O 3 across the domain, particularly at coastal sites (by ∼6 ppb), while elevated MDA8 O 3 (i.e., greater than 60 ppb) was biased low, with exceptions centered along the shore of Lake Michigan. Using the CB6 chemical mechanism or 50% reduction of NO x emissions from on-road mobile sources led to substantial domain-wide decreases in O 3 from the base case, and the model performance improved, particularly along the Lake Michigan shoreline and for the western domain. However, elevated MDA8 O 3 was more biased against measurements, compared to the model performance in the base case, except at a few sites along the shoreline. Using the Model of Emissions of Gases and Aerosols from Nature (MEGAN) instead of BEIS to estimate biogenic emissions, or increasing dry deposition of O 3 to fresh water by a factor of ten (which is unrealistic), had minor impacts on simulated O 3 over land. But, combining MEGAN with CB6 resulted in improved elevated MDA8 O 3 simulation along the western coast of Lake Michigan. Finally, using CB6 combined with a 30% reduction of on-road mobile NO x emissions and MEGAN led to the best performance. Two companion papers investigate how meteorological modeling can be improved. Together, the recommended modeling system could serve as a starting point for future O 3 modeling in the region. Highlights • Daily maximum 8-h O 3 is significantly overestimated along Lake Michigan coast. • Elevated daily maximum 8-h O 3 (>60 ppb) is biased low except at coastal sites. • Uncertainties in on-road mobile NO x emissions impact simulated daytime O 3. • Carbon Bond 6 (CB6) mechanism leads to lower O 3 than Carbon Bond V (CB05). • Biogenic emissions and dry deposition over water had minor effects on simulated O 3. [ABSTRACT FROM AUTHOR]

Highlights • Flavopunctelia soredica (FS) and Rhizoplaca chrysoleuca (RC) were transplanted. • FS and RC are applicable biomonitors for atmospheric element deposition. • FS and RC discriminate element sources and yield comparable results. • FS and RC have shorter integration time for SO 2 than for metals. Abstract The biomonitoring of atmospheric element deposition via lichen transplantation is a powerful tool for assessing air quality in polluted areas devoid of native or expected lichens. In this paper, we explore how the elemental compositions in lichens respond to road emissions and compared the lichen responses under high air pollution conditions. Two foliose lichens, Flavopunctelia soredica (FS) and Rhizoplaca chrysoleuca (RC), were transplanted along two roads in a highly polluted area of Hebei, China. FS and RC were exposed to the road emissions for 3, 6, 9 and 12 months, and 25 elements (Al, Ba, Ca, Cd, Co, Cs, Cu, Fe, K, La, Mg, Mn, Na, Ni, Pb, Rb, S, Sb, Sm, Sr, Tb, Th, Ti, V, and Zn) were measured using an inductively coupled plasma mass spectrometer (ICP-MS). The pre-exposure and post-exposure results were higher in RC for 6 metals (Ca, Cd, Pb, La, Sm, and Tb), were higher in FS for 13 elements (Al, Ba, Co, Cu, Fe, K, Mg, Mn, Ni, Rb, S, V, and Zn), but were not significantly different between FS and RC for 3 metals (Cs, Sr, and Th), indicating that the element concentrations are specific to the element and lichen species. The results also showed a certain degree of air pollution at the initial site and severe air pollution at the exposure sites. During the exposure period, FS and RC exhibited roughly similar spatio-temporal patterns in element concentrations, with significant increases observed in relation to the distance to the road and exposure time. This result suggests that FS and RC are applicable as bioaccumulators and present good comparability. The release of SO 2 in the winter heating period elevated the lichen S concentrations, for which the lichens have an integration time of <3 months, whereas the road emissions accelerated the accumulation of metals, for which the lichens have an integration time of >3 months. [ABSTRACT FROM AUTHOR]

Abstract Historical increases in emissions and atmospheric deposition of oxidized and reduced nitrogen (N) provided the impetus for extensive, global-scale research investigating the effects of excess N in terrestrial and aquatic ecosystems, with several regions within the Eastern Deciduous Forest of the United States found to be susceptible to negative effects of excess N. The Clean Air Act and associated rules have led to decreases in emissions and deposition of oxidized N, especially in eastern U.S., representing a research challenge and opportunity for ecosystem ecologists and biogeochemists. The purpose of this paper is to predict changes in the structure and function of North American forest ecosystems in a future of decreased N deposition. Hysteresis is a property of a system wherein output is not a strict function of corresponding input, incorporating lag, delay, or history dependence, particularly when the response to decreasing input is different from the response to increasing input. We suggest a conceptual hysteretic model predicting varying lag times in recovery of soil acidification, plant biodiversity, soil microbial communities, forest carbon (C) and N cycling, and surface water chemistry toward pre-N impact conditions. Nearly all of these can potentially respond strongly to reductions in N deposition. Most responses are expected to show some degree of hysteresis, with the greatest delays in response occurring in processes most tightly linked to "slow pools" of N in wood and soil organic matter. Because experimental studies of declines in N loads in forests of North America are lacking and because of the expected hysteresis, it is difficult to generalize from experimental results to patterns expected from declining N deposition. These will likely be long-term phenomena, difficult to distinguish from other, concurrent environmental changes, including elevated atmospheric CO 2 , climate change, reductions in acidity, invasions of new species, and long-term vegetation responses to past disturbance. Graphical abstract Image 1 Highlights • Past work on nitrogen (N) effects on ecosystems arose from increased N deposition. • Many forest ecosystems of the eastern U.S. have been sensitive to excess N inputs. • Federal laws have resulted in lower deposition of oxidized N in the eastern U.S. • A hysteretic model is proposed for forest recovery from decreased N deposition. • N-impacted forests should show time lags recovering toward pre-impact conditions. Nitrogen (N)-impacted forest ecosystems are predicted to exhibit a time lag of varying duration toward recovery initiated by current declines in atmospheric N deposition. [ABSTRACT FROM AUTHOR]

Abstract For many years, monitoring and determining the radioactivity of 137Cs in the environment has considerable interest. This paper presents monitoring 137Cs deposition fluxes during the period from 2009 to 2011. Dust fallout samples were collected from ten locations in Kuwait, and 137Cs concentrations were determined using ultra low spectrometry system. The average of the annual atmospheric deposition fluxes of 137Cs was 4.3, with an extreme value reaching 50 Bq m−2. The monthly deposition rates of 137Cs were attributed to seasonal increases in the spring. 137Cs deposition fluxes showed a significant relationship with dust deposition and precipitation rates, where the correlation between the monthly dust fallout and the 137Cs deposition fluxes and precipitation rates were approximately 0.95 and 0.81, respectively. The spatial monthly distribution of 137Cs fluxes showed high rates in the southeastern part of Kuwait while the lowest rates were recorded along the coastlines. A strong correlation was observed between the annual 137Cs and 40K deposition rates considering that both radionuclides deposition were governed by similar conditions. It was concluded that long-range transport from the northwestern areas along with the effects from local dust washout and the site specify played a major role in controlling the rate of 137Cs deposition. The estimated annual effective dose equivalent due to external and internal exposures was insignificant and can be ignored. It is worthwhile to continue investigating the source origin of 137Cs in Kuwait to enhance understanding of the radiological hazards in the country. Highlights • Dust fallout samples were collected from ten locations in Kuwait; 137Cs concentrations were determined using ultra low gamma spectrometry system. • 137Cs deposition fluxes were continuously observed and showed seasonally variations. • The concentration of 137Cs has been found to be enriched by long-range transport from its surroundings, mainly by the northwesterly dust sources. • The radiological hazards associated with 137Cs deposition in Kuwait are very small and can be ignored. [ABSTRACT FROM AUTHOR]

Abstract Recent studies have confirmed historic atmospheric deposition of uranium in Antarctica, with a steep and significant increase in levels deposited since the 1980s in Antarctic Peninsula ice core samples. To date, however, there has been little or no attention paid to uranium in the Antarctic food web. Here, we present results for uranium content in scales of three common nototheniid species (Trematomus bernacchii , Gobionotothen gibberifrons , Notothenia coriiceps) from coastal waters off James Ross Island (Antarctic Peninsula). While mean total uranium levels (mean ± SD) were low and similar between species (N. coriiceps 0.08 μg g−1 ± 0.01, T. bernacchii 0.17 μg g−1 ± 0.10; G. gibberifrons 0.11 μg g−1 ± 0.04), linear regressions against standard length indicated bioaccumulation in T. bernacchii (ANOVA, F = 7.8349, P = 0.0076). We suggest this may be the result of dietary specialisation on prey with calcareous shells that accumulate uranium. To the best of our knowledge, this paper provides the first quantitative baseline data on uranium levels in coastal Antarctic nototheniids. While the low levels recorded are unlikely to represent a threat within the food chain, we suggest that further long-term trophic studies (including stable isotope analysis) are needed, recognising that the feeding ecology of individual species (and even individuals) can have a strong effect on overall trends. Graphical abstract Image 1 Highlights • First quantitative baseline uranium levels presented for Antarctic nototheniids. • Levels low but emerald rockcod show evidence of bioaccumulation. • Bioaccumulation linked with dietary specialisation on molluscs? • Possible links with atmospheric deposition and climate change. • In depth trophic studies needed on Antarctic food-web dynamics. [ABSTRACT FROM AUTHOR]

Abstract Molecular contaminants outgassed from organic materials used for the spacecraft degrade the performance of optical surfaces of spacecraft. The influence of contaminants outgassed from epoxy resin on the spectral transmittance of the quartz substrate was investigated with an in-situ measurement system. The system can deposit the contaminants on temperature-controlled quartz substrates and the transmittance spectra were measured immediately after deposition in vacuum ambient. We obtained the optical constants of the contaminant using transmittance spectrum and simple optical models for optical calculations. The optical constants were described with a harmonic oscillator model and an effective medium approximation model. This paper reports the in-situ measurement results of transmittance spectra of the epoxy-resin-induced contaminants in deposition and desorption process. The thin contamination layer decreased the transmittance in the ultraviolet region. However, the contamination was entirely desorbed at −20 °C and transmittance recovered to the initial value. In addition, the results of optical calculations using the obtained optical constants were compared to the measurement results. Highlights • Transmittance of contamination was measured during deposition and desorption process. • Thin contamination layer notably decreased transmittance in the ultraviolet region. • Little influence of the epoxy-resin-induced contamination is expected over 0 °C. • Simple optical model express optical properties of epoxy-resin-induced contamination. • Quartz crystal microbalance may monitored inaccurate thickness in desorption process. [ABSTRACT FROM AUTHOR]

As we inhale, the air drawn through our nose undergoes successive accelerations and decelerations as it is turned, split and recombined before splitting again at the end of the trachea as it enters the bronchi. Fully describing the dynamic behaviour of the airflow and how it transports inhaled particles poses a severe challenge to computational simulations. In this paper we explore two aspects: the dynamic behaviour of airflow during a rapid inhalation (or sniff) and the transport of inhaled aerosols. The development of flow unsteadiness from a laminar state at entry to the nose through to the turbulent character of tracheal flow is resolved using accurate numerical models with high performance computing-based large scale simulations. Combining the flow solution with a Lagrangian computation reveals the effects of flow behaviour and airway geometry on the deposition of inhaled microparticles. Improved modelling of airflow and delivery of therapeutic aerosols could be applied to improve diagnosis and treatment. [ABSTRACT FROM AUTHOR]

Building on work by Kampa et al. (2014) about the liquid distribution in multi-layer oil mist filters, a mesoscale empirical model is proposed for their efficiency. It decomposes the total penetration into a product of independent ‘building blocks’ that are aligned with the mesoscale liquid distribution in steady state, essentially in the form of an oil film and a channel region. The film (typically one very thin region per sandwich) is associated with a film penetration P film and the channel region (consisting typically of multiple layers) with a channel penetration P channe l . The first layer of wettable media also represents a separate contribution P 1st layer . A method is described to derive these unit penetrations from a set of measurements. Experiments are then carried out with filters composed of conventional glass microfiber media, both wettable and non-wettable to compressor oil, in which the fractional penetration of the entire sandwich was measured by SMPS between about 30 and 700 nm. It is shown that the film penetration is substantially reduced for particles above about 100 nm in comparison to that of the dry media due to enhanced inertial deposition, while the channel penetration is generally higher across the board, probably because of a loss of active fiber in the partially saturated media. The last part of the paper is dedicated to practical consequences of this efficiency model. It is shown that the fractional efficiency for an arbitrary number of (identical) layers can be predicted quite accurately from the unit penetrations. Additional measurements of the total downstream concentration as a function of time are used to discuss and explain changes from start-up until steady state. [ABSTRACT FROM AUTHOR]

Abstract: Wind-driven rain (WDR) is an important factor in the dry and wet deposition of atmospheric pollutants on building facades. In the past, different calculation models for WDR deposition on building facades have been developed and progressively improved. Today, the models that are most advanced and most frequently used are the semi-empirical model in the ISO Standard for WDR assessment (ISO), the semi-empirical model by Straube and Burnett (SB) and the CFD model by Choi. This paper compares the three models by applying them to four idealised buildings under steady-state conditions of wind and rain. In each case, the reference wind direction is perpendicular to the windward facade. For the CFD model, validation of wind-flow patterns and WDR deposition fluxes was performed in earlier studies. The CFD results are therefore considered as the reference case and the performance of the two semi-empirical models is evaluated by comparison with the CFD results based on two criteria: (1) ability to model the wind-blocking effect on the WDR coefficient; and (2) ability to model the variation of the WDR coefficient with horizontal rainfall intensity Rh. It is shown that both the ISO and SB model, as opposed to the CFD model, cannot reproduce the wind-blocking effect. The ISO model incorrectly provides WDR coefficients that are independent of Rh, while the SB model shows a dependency that is opposite to that by CFD. In addition, the SB model can provide very large overestimations of the WDR deposition fluxes at the top and side edges of buildings (up to more than a factor 5). The capabilities and deficiencies of the ISO and SB model, as identified in this paper, should be considered when applying these models for WDR deposition calculations. The results in this paper will be used for improvement and further development of these models. [Copyright &y& Elsevier]

Abstract: Water soluble organic nitrogen (WSON) compounds are ubiquitous in precipitation and in the planetary boundary layer, and therefore are a potential source of bioavailable reactive nitrogen. This paper examines weekly rain data over a period of 22 months from June 2005 to March 2007 collected in 2 types of rain collector (bulk deposition and “dry + wet” deposition) located in a semi-rural area 15 km southwest of Edinburgh, UK (N55°51′44″, W3°12′19″). Bulk deposition collectors are denoted in this paper as “standard rain gauges”, and they are the design used in the UK national network for monitoring precipitation composition. “Dry + wet” deposition collectors are flushing rain gauges and they are equipped with a rain detector (conductivity array), a spray nozzle, a 2-way valve and two independent bottles to collect funnel washings (dry deposition) and true wet deposition. On average, for the 27 weekly samples with 3 valid replicates for the 2 types of collectors, dissolved organic nitrogen (DON) represented 23% of the total dissolved nitrogen (TDN) in bulk deposition. Dry deposition of particles and gas on the funnel surface, rather than rain, contributed over half of all N-containing species (inorganic and organic). Some discrepancies were found between bulk rain gauges and flushing rain gauges, for deposition of both TDN and DON, suggesting biological conversion and loss of inorganic N in the flushing samplers. [Copyright &y& Elsevier]

This paper presents salinity data of marine aerosols in a Brazilian coastal area at sites closer to the shore and discusses the influence of wind regime. Results show that measurements of marine salt deposition are strongly influenced by wind speeds above the critical value of 3.0ms−1. Although there is no agreement in literature yet as to how much this threshold is, the level of 3.0ms−1 is similar to the one found in a study carried out in Spain. An exponential variation of salt concentration with wind speed is presented in previous published papers. However, in the studied case, another relationship is proposed, which is based on chloride deposition on the wet candle device and wind speeds higher than 3.0ms−1 weighted by the accumulated time in which these wind speeds are observed, what seems to be particularly useful when wind speed ranges around the critical value. [Copyright &y& Elsevier]

Abstract: Effectiveness of street sweeping and washing (S/W) for controlling ambient “total suspended particles (TSP)” was evaluated by TSP measurements and determining silt load from active traffic streets. A modified regenerative-air vacuum sweeper (RAVS) and a washer were used in this study. The sweeper made a pass followed by the washer. The S/W efficiencies were obtained based on the experimental data of silt loading and TSP. It was found that the direct impact of sweeping on ambient TSP emissions was short-lived lasting no more than 3–4h. When a vacuum sweeper and a washer, respectively, did a good job collecting or cleaning the visible fine particles on roads, the method of S/W tested in this work was effective at removing the sources of the road dust particles. This paper concludes that street sweeping followed by washing was found to offer a measurable reduction in TSP emission potentials. Typically, the reduction efficiency of ambient TSP is up to 30%. Finally, correlated with (based on silt loading), a useful equation is proposed to estimate the S/W efficiency, (based on TSP) with a standard error of ±20%. It seems feasible to predict the reduction efficiency of ambient TSP controlled by the regenerative-air vacuum sweeper and washer used in this work for engineering applications. Effects of traffic volume and wind velocity on the S/W efficiencies are also discussed in the paper. [Copyright &y& Elsevier]

Abstract: An air pollution index (API) reporting system is introduced to selected cities of China for public communication on air quality data. Shanghai is the first city in China providing daily average API reports and forecasts. This paper describes the development of an artificial neural network (ANN) model for the API forecasting in Shanghai. It is a multiple layer perceptron (MLP) network, with meteorological forecasting data as the main input, to output the next day average API values. However, the initial version of the MLP model did not work well. To improve the model, a series of tests were conducted with respect to the training method and structure optimization. Based on the test results, the training algorithm was modified and a new model was built. The new model is now being used in Shanghai for API forecasting. Its performance is shown reasonably well in comparison with observation. The application of the old model was only weakly correlated with observation. In 1-year application, the correlation coefficients were 0.2314, 0.1022 and 0.1710 for TSP, and , respectively. But for the new model, for over 8 months application, the correlation coefficients are raised to 0.6056, 0.6993 and 0.6300 for , , and . Further, the new algorithm does not rely on manpower intervention so that it is now being applied in several other Chinese cities with quite different meteorological conditions. The structure of the model and the application results are presented in this paper and also the problems to be further studied. [Copyright &y& Elsevier]

As potential carriers of hazardous pollutants, airborne particles may deposit onto surfaces due to gravitational settling. A modified Markov chain model to predict gravity induced particle dispersion and deposition is proposed in the paper. The gravity force is considered as a dominant weighting factor to adjust the State Transfer Matrix, which represents the probabilities of the change of particle spatial distributions between consecutive time steps within an enclosure. The model performance has been further validated by particle deposition in a ventilation chamber and a horizontal turbulent duct flow in pre-existing literatures. Both the proportion of deposited particles and the dimensionless deposition velocity are adopted to characterize the validation results. Comparisons between our simulated results and the experimental data from literatures show reasonable accuracy. Moreover, it is also found that the dimensionless deposition velocity can be remarkably influenced by particle size and stream-wise velocity in a typical horizontal flow. This study indicates that the proposed model can predict the gravity-dominated airborne particle deposition with reasonable accuracy and acceptable computing time. [ABSTRACT FROM AUTHOR]

Aerosol acidity has significant implications for atmospheric processing, and high time-resolution measurements can provide critical insights into those processes. This paper reports diurnal variations of aerosol acidity characterized using an open thermodynamic system in Guangzhou, China. Hourly measurements of PM 2.5 -associated ionic species and related parameters were carried out during June–September 2013 followed by application of the Extended Aerosol Inorganic Model in open mode to estimate aerosol pH. The model-estimated aerosol pH was 2.4 ± 0.3, and the pH diurnal profile exhibited peaks in the early morning (6 a.m.) and troughs in the afternoon (2 p.m.) that appeared to be constrained by liquid water content (LWC) and free H + . A linear regression model was developed to predict aerosol pH, which performed strongly with 4 variables during daytime (NH 4 + , Na + , SO 4 2− and RH; R 2  = 0.95) and 3 during nighttime (NH 4 + , SO 4 2− and RH; R 2  = 0.91). The effect of aerosol acidity on the partitioning of HNO 3 , HCl and NH 3 was studied based on theoretical considerations and measurement data. The fractions in particulate phase for acidic compounds correlated strongly with pH (R 2  = 0.64–0.69) while that for NH 3 , interestingly, was weak (R 2  = 0.17). Analytical expressions were developed to explain these observations and it was concluded that the partitioning of HCl and HNO 3 was more sensitive to pH compared to that of NH 3 . These results are significant in terms of potential atmospheric depletion rates of HCl and HNO 3 in the region and stress the need for future studies in this direction. [ABSTRACT FROM AUTHOR]

This paper includes the results of chemical composition of bulk deposition samples collected simultaneously at urban (Poznań city) and forest (Jeziory) sites in central Poland, between April 2013 and October 2014. Rainwater samples were analyzed for trace elements (As, Zn, Ni, Pb, Cu, Cr, Cd) and physicochemical parameters. Overall, three metals, i.e. Zn, Pb and Cu were the most abundant anthropogenic constituents of rainwater samples from both locations. In Poznań city, the rainwater concentrations of trace elements did not differ significantly between spring and summer. However, they were elevated and more variable during the cold season (fall and winter), suggesting strong contribution from local high-temperature processes related to coal combustion (commercial and residential sector). In contrast to the urban site, relatively low variability in concentrations was found for Cu, Ni, Zn at the forest site, where direct impact of emission from vehicle traffic and coal-fired combustion (power plants) was much lower. The bulk deposition fluxes of Ni, As, Pb and Zn at this site exhibited a clear trend, with higher values during the cold season (fall and winter) than in spring and summer. At the urban site, the sums of total bulk deposition fluxes of Zn, Cu, Pb, Ni, As, Cr, Cd were as follows: 8460.4, 4209.2, 2247.4, 1882.1, 606.6, 281.6 and 31.4 μg m − 2 . In addition, during the winter season, a significantly higher deposition fluxes of Cu and Zn were observed for rain (on average 103.8 and 129.4 μg m − 2 , respectively) as compared to snow (19.7 μg Cu m − 2 and 54.1 μg Zn m − 2 ). This suggests that different deposition pattern of trace elements for rain, mixed and snow was probably the effect of several factors: precipitation type, changes in emission and favorable meteorological situation during rain events. [ABSTRACT FROM AUTHOR]

For the first time, this paper develops an integrated and spatially-distributed modelling approach, linking atmospheric deposition, soil erosion and sewer transport models, to assess the transfer of traffic-related pollutants in urban areas. The modelling system is applied to a small urban catchment near Paris. Two modelling scenarios are tested by using experimentally estimated and simulated atmospheric dry deposits. Simulation results are compared with continuous measurements of water flow and total suspended solids (TSS) at the catchment outlet. The performance of water flow and TSS simulations are satisfying with the calibrated parameters; however, no significant difference can be noticed at the catchment outlet between the two scenarios due to the “first flush” effects. Considering the Cu, BaP and BbF contents of different particle size classes, simulated event mean concentration of each pollutant is compared with local in-situ measurements. Finally, perspectives to improve model performance and experimental techniques are discussed. [ABSTRACT FROM AUTHOR]

The atmospheric aerosols around the Bohai Bay are affected intensively by the surrounding industrial, shipping and other human activities. Although atmospheric dry deposition is an important way for nutrients to enter the Bohai Bay, few studies explore the distribution patterns, source and deposition fluxes of typical nutrients in aerosols and their impacts on the marine ecosystem. This paper explored the spatial-temporal distribution of typical aerosol nutrients in summer and autumn, and their source and ecological effects were illustrated further. The mean concentration of dissolved total phosphorus (DTP), dissolved total nitrogen (DTN), dissolved organic nitrogen (DON), dissolved inorganic nitrogen (DIN), ammonium (NH 4 –N), nitrate (NO 3 –N), nitrite (NO 2 –N), silicate (SiO 3 –Si), phosphate (PO 4 –P), and dissolved organic phosphorus (DOP) were 31.22, 847.22, 288.19, 559.77, 288.19, 304.00, 253.65, 2.12, 15.74 and 15.48 nmol/m3, respectively, while their fluxes were corresponding to 0.61, 8.36, 2.52, 4.90, 1.41, 2.49, 0.02, 0.04, 0.19 and 0.26 mmol/(m2 month). Typical aerosol nutrient concentrations in autumn were mostly higher than those in summer, with high values occurring mainly in the central region. The potential sources of pollution were mainly concentrated in Shandong and Mongolia, and the sources of pollution were mainly agriculture, dust and industry. The large N:P and N:Si ratios in the dry deposition likely exacerbated Si and P limitation in the water column. These results provided the data basis for evaluating the pollution status and revealed that the dry deposition of aerosol nutrients should not be neglected by the ecological environment in the Bohai Bay. [Display omitted] • Inorganic nitrogen is one of the main pollutants in Bohai Bay's atmosphere. • The high N/P ratio in Bohai Bay should, to some extent, be attributed to dry deposition. • Pollutants in the atmosphere of Bohai Bay come mainly from the surrounding air masses. • Aerosol N and P are impacted by the long-distance transportation of contaminants. • Dry deposition can exacerbate phosphorus and silicon limitation in ocean surface waters. [ABSTRACT FROM AUTHOR]

This paper introduces a new parameter to characterize the random component in temporal variability of atmospheric pollutants and proposes a simple statistical technique for its evaluation. That parameter is the net decay time (or the time scale) of the local anomalies in concentrations of atmospheric pollutants, rather than the traditionally used chemical lifetimes of total amounts of the species. Using widely available data of hourly multi-year surface trace gas pollutant concentrations we demonstrate a simplified way to estimate the net decay time with an exponential approximation of lag-correlation functions. We assessed the decay times of fluctuations in observations of eight atmospheric pollutants (SO 2 , NO, NO 2 , NO y , O 3 , CO, NH 3 , and HNO 3 ) at two urban sites and one cleaner rural site in the Eastern US. The time scales of temporal fluctuations (net decay times) vary from about one hour to slightly more than one day. These scales are generally much shorter in urban environments than in remote regions. We also compared day- and night-time observations in warm and cold seasons. At night in the cold season, time scales of fluctuations in atmospheric pollutants are usually the longest. Such estimates should be useful to air quality prediction, public health, and satellite remote sensing research communities. [ABSTRACT FROM AUTHOR]

In this paper, we present concentrations of an array of major and trace elements (Ag, Al, As, Ba, Bi, Cd, Co, Cr, Cu, Fe, Mn, Mo, Rb, Sb, Sc, Sr, Th, Tl, U, V, Zn) in living Sphagnum mosses from four southern German bogs and compare them with moss monitoring data of the respective regions. To do this, Sphagnum mosses were collected in Upper Bavaria (Oberbayern, OB) and the Northern Black Forest (Nordschwarzwald, NBF). Surfaces of Sphagnum carpets were marked with plastic mesh and, one year later, the annual moss production was harvested. Up to 12 samples (40 cm × 40 cm) were collected per site, and 6–10 sites investigated per bog. The concentrations of these elements were then determined in acid digests using sector field ICP-MS. Variations within a given sampling site were in the range of 2 to 3-fold for all major and trace element concentrations except for Mn (12-fold) and Tl (38-fold). For most of the elements, concentrations between bogs of a given region were significantly different and atmospheric deposition of particles seems to be considerably affected by local circumstances such as tree canopy interception and microtopography. Comparing trace element concentrations measured in Sphagnum mosses for 2007 with published moss monitoring data for 2005 resulted in a very good agreement for most elements. Clearly, Sphagnum mosses from bogs are useful biomonitors for estimating atmospheric contamination by metals. This supports the use of Sphagnum in atmospheric deposition monitoring especially in cases where Sphagnum is abundant (e.g., boreal forests). In regions with neither bogs nor forests, living Sphagnum moss bags could be used to the same effect. [ABSTRACT FROM AUTHOR]

As the atmospheric environment pollution has been becoming more and more serious in China, it is highly desirable to develop a scientific and effective early warning system that plays a great significant role in analyzing and monitoring air quality. However, establishing a robust early warning system for warning the public in advance and ameliorating air quality is not only an extremely challenging task but also a public concerned problem for human health. Most previous studies are focused on improving the prediction accuracy, which usually ignore the significance of uncertainty information and comprehensive evaluation concerning air pollutants. Therefore, in this paper a novel robust early warning system was successfully developed, which consists of three modules: evaluation module, forecasting module and characteristics estimating module. In this system, a new dynamic fuzzy synthetic evaluation is proposed and applied to determine air quality levels and primary pollutants, which can be regarded as the research objectives; Moreover, to further mine and analyze the characteristics of air pollutants, four different distribution functions and interval forecasting method are also employed that can not only provide predictive range, confidence level and the other uncertain information of the pollutants future values, but also assist decision-makers in reducing and controlling the emissions of atmospheric pollutants. Case studies utilizing hourly PM 2.5 , PM 10 and SO 2 data collected from Tianjin and Shanghai in China are applied as illustrative examples to estimate the effectiveness and efficiency of the proposed system. Experimental results obviously indicated that the developed novel early warning system is much suitable for analyzing and monitoring air pollution, which can also add a novel viable option for decision-makers. [ABSTRACT FROM AUTHOR]

In the framework of the UNECE Task Force on Measurement and Modelling (TFMM) under the Convention on Long-range Transboundary Air Pollution (LRTAP), the EURODELTAIII project is evaluating how well air quality models are able to reproduce observed pollutant air concentrations and deposition fluxes in Europe. In this paper the sulphur and nitrogen deposition estimates of six state-of-the-art regional models (CAMx, CHIMERE, EMEP MSC-W, LOTOS-EUROS, MINNI and CMAQ) are evaluated and compared for four intensive EMEP measurement periods (25 Feb–26 Mar 2009; 17 Sep–15 Oct 2008; 8 Jan–4 Feb 2007 and 1–30 Jun 2006). For sulphur, this study shows the importance of including sea salt sulphate emissions for obtaining better model results; CMAQ, the only model considering these emissions in its formulation, was the only model able to reproduce the high measured values of wet deposition of sulphur at coastal sites. MINNI and LOTOS-EUROS underestimate sulphate wet deposition for all periods and have low wet deposition efficiency for sulphur. For reduced nitrogen, all the models underestimate both wet deposition and total air concentrations (ammonia plus ammonium) in the summer campaign, highlighting a potential lack of emissions (or incoming fluxes) in this period. In the rest of campaigns there is a general underestimation of wet deposition by all models (MINNI and CMAQ with the highest negative bias), with the exception of EMEP, which underestimates the least and even overestimates deposition in two campaigns. This model has higher scavenging deposition efficiency for the aerosol component, which seems to partly explain the different behaviour of the models. For oxidized nitrogen, CMAQ, CAMx and MINNI predict the lowest wet deposition and the highest total air concentrations (nitric acid plus nitrates). Comparison with observations indicates a general underestimation of wet oxidized nitrogen deposition by these models, as well as an overestimation of total air concentration for all the campaigns, except for the 2006 campaign. This points to a low efficiency in the wet deposition of oxidized nitrogen for these models, especially with regards to the scavenging of nitric acid, which is the main driver of oxidized N deposition for all the models. CHIMERE, LOTOS-EUROS and EMEP agree better with the observations for both wet deposition and air concentration of oxidized nitrogen, although CHIMERE seems to overestimate wet deposition in the summer period. This requires further investigation, as the gas-particle equilibrium seems to be biased towards the gas phase (nitric acid) for this model. In the case of MINNI, the frequent underestimation of wet deposition combined with an overestimation of atmospheric concentrations for the three pollutants indicates a low efficiency of the wet deposition processes. This can be due to several reasons, such as an underestimation of scavenging ratios, large vertical concentration gradients (resulting in small concentrations at cloud height) or a poor parameterization of clouds. Large differences between models were also found for the estimates of dry deposition. However, the lack of suitable measurements makes it impossible to assess model performance for this process. These uncertainties should be addressed in future research, since dry deposition contributes significantly to the total deposition for the three deposited species, with values in the same range as wet deposition for most of the models, and with even higher values for some of them, especially for reduced nitrogen. [ABSTRACT FROM AUTHOR]

We present measurements of atmospheric concentrations of ammonia and ammonium in the Netherlands over the period 1993–2014 and measurements of wet deposition of ammonium for 1985–2014. The various time series have been obtained at 16 monitoring stations from the Dutch National Air Quality Monitoring Network. The monitoring stations are geographically homogenously spread over the Netherlands and are equally distributed over regions with relatively low, moderate and high ammonia emission. During the period covered, changes in the monitoring have occurred. To obtain consistent time series, data are revalidated or corrected when necessary, according to current validation procedures or latest technical insights. The time series of ammonia concentrations are gap filled and time series corrected for meteorological influences are constructed. The course in the ammonia concentrations shows roughly two periods. For 1993–2004, the ammonia concentrations show a downward trend of 36%, which is statistically significant with a confidence interval (CI) of 99%. For 2005–2014, an upward trend of 19% (CI 90%) is reported. Correcting time series of ammonia concentrations for meteorological influences enhances the statistical reliability of the derived trends. This resulted in trends of −40% (CI 99%) and 24% (CI 95%) respectively. For the full period there exists no trend in ammonia concentrations due to a trend in atmospheric conditions. For 2005–2014 ammonia concentrations increased especially in springtime, while showing no change in winter months. After correcting for meteorological influences, all seasons in this period show an increase in ammonia concentrations although the increase in the spring months is still the largest. For 1993–2014 the reported ammonia emissions in the Netherlands declined in both periods with respectively 51% and 22%. The trends in emissions and ammonia concentrations correspond in the period 1993–2004 whilst over the period 2005–2014, the trends in emissions and concentrations of ammonia diverge. This divergence is for roughly a third accounted for by processes related to changes in chemical climate (see accompanying modelling paper by Wichink Kruit et al., 2016) but it is not clear what explains the remaining difference in trends. For 1993–2014, downward trends of wet deposition of ammonium and ammonium in aerosol are found to be 47% and 68%, respectively. A split into two periods is not found as is the case with the ammonia concentration. However, although statistically not significant, both wet deposition of ammonium and ammonium in aerosol show a leveling off in decline between 2005 and 2014. [ABSTRACT FROM AUTHOR]

In the last decades, in Europe a large effort was carried out to reduce sulphur and nitrogen emission in the atmosphere, in order to improve air quality and reduce the acidity of atmospheric deposition and the amount of nitrogen compounds it carries to terrestrial and aquatic ecosystems. This resulted in a sharp decrease in the deposition of sulphate and acidity, while until recently a decrease of the atmospheric load of nitrogen compounds was not evident. In this paper, we focus on the subalpine and alpine areas in North-Western Italy and Southern Switzerland (Canton Ticino), receiving high deposition of atmospheric pollutants transported from emission sources in the Po Valley, one of the most urbanised and industrialised areas of Europe. Long-term studies, covering a 30-year period (1984–2014), were carried out on the chemistry of atmospheric deposition in this area and its effects on surface water bodies through a cooperation between Swiss and Italian research institutions. A total of 14 atmospheric deposition wet-only sampling sites operate in this area, covering a wide latitudinal and altitudinal range (about 200–1900 m a.s.l.). A spatial gradient in the deposition of sulphate and nitrogen compounds was evident both in the 1990s and in recent times (2008–2012), with highest values in the south-eastern part of the area, close to the major emission sources. Deposition also varied depending on local topography. The analysis of long-term trends revealed a large proportion of significant decreasing trends in the concentration of both sulphate and nitrogen compounds. Deposition changes were less evident, due to the high interannual variability in the data, caused by the highly variable precipitation amount, ranging from 1200–1300 mm in dry years to 3000 mm in wet years. Sulphate concentrations and deposition decreased steadily since the 1980s, while ammonium and nitrate showed a widespread decrease only in the most recent period (after 2006). However, nitrogen wet deposition is still high with respect to critical loads: inorganic N deposition ranges from 60–70 meq m −2 y −1 (as the sum of ammonium and nitrate) at the alpine sites to 120–140 meq m −2 y −1 at the southern lowland sites. Deposition of ammonium has acquired an increasing importance in time, especially at the southern, more polluted sites: the relative contribution of reduced N to wet N deposition passed from about 50% in the early 1990s to 56–57% in recent years. The observed temporal changes in nitrogen deposition followed the emission decrease but with a delay. This aspect may be relevant in monitoring the effects of emission reductions as a result of the enforcements of international and national regulations. [ABSTRACT FROM AUTHOR]

Atmospheric emissions of reactive nitrogen have increased significantly on a global scale due to increases of the use of artificial fertilizer and the burning of fossil fuels. The Asian region has been identified as a high-risk area for nitrogen deposition effects on ecosystems. This paper describes a measurement-based assessment of nitrogen deposition carried out in cooperation with the Acid Deposition Monitoring Network in East Asia (EANET). The investigation aimed to understand the status and variability of dry, wet and total deposition of oxidized and reduced nitrogen over a 10-year period (2003–2012) at 8 remote sites in Japan (Rishiri, Tappi, Sado-seki, Happo, Oki, Yusuhara, Ogasawara and Hedo). Dry deposition amounts were estimated by the inferential method. All of the sites except Rishiri and Ogasawara had high mean annual total nitrogen deposition amounts of approximately 10 kg N ha −1 year −1 or more, over the 10-year period. The high contribution of oxidized nitrogen deposition in the central area is mainly caused by domestic emissions, especially for dry deposition processes. An increase in reduced nitrogen deposition originating from regional emissions was found, and is likely to result in a subsequent increase in the total nitrogen deposition in Japan. Since neither a clear increasing nor decreasing trend in total nitrogen deposition was found at any site during the 10-year period, the nitrogen deposition amounts remained high thorough the long period in Japanese remote area. The spatial distribution of nitrogen deposition was found to be significant when uncertainties were accounted for. [ABSTRACT FROM AUTHOR]

A large emission of air pollutants from the Asian continent has caused transboundary air pollution, especially in northeastern Asia. This paper evaluates sulfate deposition at a leeward area of Asian continent, i.e., the Nagaoka observation station located along the Sea of Japan. We have monitored atmospheric sulfate deposition and its sulfur isotopic ratio for 28 years at the station. The sulfur isotopic ratios of non-sea-salt sulfate (δ 34 Snss) ranged from 0.0 to +6.2‰. The isotopic ratios of local emission and Chinese coal sulfur showed negative and positive values, respectively. Several statistically significant trends were detected on the deposition of non-sea-salt sulfate (nss-SO 4 2− ) during the study period. The decrease of nss-SO 4 2− deposition since the middle of 1980s was considered to have been caused by local anthropogenic SO 2 emission that showed relatively low δ 34 Snss values during the period. The increase of nss-SO 4 2− deposition from the end of 1990s to the second half of 2000s was interpreted to have been caused by the change in SO 2 emission in China because the δ 34 Snss values increased during the period with the winter values getting closer to the averaged value of Chinese coal sulfur. The decreasing trend of nss-SO 4 2− deposition from the middle of 2000s was likely affected by reduction of Chinese SO 2 emission judging from the decrease in δ 34 Snss values in the period. Mass balance calculations suggested that sulfur released by coal combustion in China during 1990s contributed by about 40% of annual total sulfur deposition in Nagaoka, and its contribution increased up to 60% in the middle of 2000s. The contribution turned to decrease after that peak, which was in harmony with the temporal change of emission from China. [ABSTRACT FROM AUTHOR]

Dry deposition process is one of the important pathways for the removal of particles from atmosphere. It is the result of a combination of different environmental and physical factors as atmospheric conditions, particle properties, characteristics of the canopy. For this latter factor, urban canopy represents unevenly combinations of different types of surface elements that increases the complexity of deposition process phenomena. Therefore, particle dry deposition on urban surfaces is not easy to configure and, although empirical or semi-empirical models in literature have been developed to address this aspect, there is not standardized and commonly accepted criteria, especially for submicron particles. In this paper, comparisons of different dry deposition models and measurement data by experimental campaigns, covering for different surface roughness conditions, i.e. from four Italian cities and urban environments of other countries, are performed. Giardina et al. (2017b) model, by using a Brownian diffusion resistance as proposed in this paper, seems to capture the main dry deposition processes for the examined contexts. • A pathway to remove pollutants in atmosphere is the dry deposition process. • Modelling of dry deposition phenomena over urban canopies is performed. • Comparisons were performed between deposition velocity models and experiments covering for different surface roughness conditions. • The proposed Brownian diffusion resistance captures the main dry deposition processes for the examined urban canopies. [ABSTRACT FROM AUTHOR]

This study aims to develop a 1D model that makes it possible to calculate the daily total 7Be wet deposition flux. For this purpose, long-term (2015–2021), high-frequency (daily) and time-synchronized series of observations of 7Be wet deposition flux and its atmospheric activity concentration are analyzed in this paper. Daily mean 7Be activity concentration in the atmosphere, daily total 7Be wet deposition flux and mean 7Be activity concentration, washout ratio, deposition velocity and scavenging coefficient with individual precipitation events lie in the range of 0.1–17 mBq m−3, 0.8–117.2 Bq m−2 d−1, 0.4–11.3 Bq L−1, 331–3799, 0.2–24.7 cm s−1 and (0.8–35.6) × 10−5 s−1, respectively. Quantitative estimates of the influence of precipitation parameters (amount, intensity and duration) on the daily total 7Be wet deposition flux, mean 7Be activity concentration in precipitation, washout ratio, deposition velocity and scavenging coefficient with individual precipitation events have been obtained using correlation analysis. It has been found that precipitation amount has the greatest influence on 7Be deposition flux and deposition velocity, precipitation intensity has the greatest influence on washout ratio and scavenging coefficient, and precipitation duration has the greatest influence on 7Be activity concentration in precipitation. The relationships between these parameters have been parameterized. Based on these parameterizations, five 1D models that calculate the daily total 7Be wet deposition flux have been introduced and validated against the observation data. It has been revealed that the model, which is based on deposition velocity parameterization and uses the data on 7Be activity concentration in the atmosphere and the daily amount of precipitation as predictors, reproduces the highest fraction of the observational data (88%) with the lowest average calculation error (32%) compared to the other four models. [Display omitted] • Precipitation of greater amount, intensity and duration wash out more 7Be. • The more precipitation amount, intensity and duration, the less 7Be activity in it. • Atmospheric 7Be is washed out by heavy rain 2.5 times faster than by light rain. • A ninefold increase in atmospheric 7Be doubles the residence time during rain. • Best deposition flux simulation is obtained with atmospheric 7Be and rain amount data. [ABSTRACT FROM AUTHOR]

The Fukushima Daiichi Nuclear Plant (FDNPP) accident resulted in huge environmental and socioeconomic impacts to Japan. To document the actual environmental and socioeconomic effects of the FDNPP accident, we describe here atmospheric and marine contamination due to radionuclides released from the FDNPP accident using papers published during past five years, in which temporal and spatial variations of FDNPP-derived radionuclides in air, deposition and seawater and their mapping are recorded by local, regional and global monitoring activities. High radioactivity-contaminated area in land were formed by the dispersion of the radioactive cloud and precipitation, depending on land topography and local meteorological conditions, whereas extremely high concentrations of 131 I and radiocesium in seawater occurred due to direct release of radioactivity-contaminated stagnant water in addition to atmospheric deposition. For both of atmosphere and ocean, numerical model simulations, including local, regional and global-scale modeling, were extensively employed to evaluate source terms of the FDNPP-derived radionuclides from the monitoring data. These models also provided predictions of the dispersion and high deposition areas of the FDNPP-derived radionuclides. However, there are significant differences between the observed and simulated values. Then, the monitoring data would give a good opportunity to improve numerical modeling. [ABSTRACT FROM AUTHOR]

In this paper we investigated the possibility to use moss bags to detect pollution inputs - metals, metalloids and polycyclic aromatic hydrocarbons (PAHs) - in sites chosen for their different land use (agricultural, urban/residential scenarios) and proximity to roads (sub-scenarios), in a fragmented conurbation of Campania (southern Italy). We focused on thirty-nine elements including rare earths. For most of them, moss uptake was higher in agricultural than in urban scenarios and in front road sites. Twenty PAHs were analyzed in a subset of agricultural sites; 4- and 5-ringed PAHs were the most abundant, particularly chrysene, fluoranthene and pyrene. Overall results indicated that investigated pollutants have a similar spatial distribution pattern over the entire study area, with road traffic and agricultural practices as the major diffuse pollution sources. Moss bags proved a very sensitive tool, able to discriminate between different land use scenarios and proximity to roads in a mixed rural-urban landscape. [ABSTRACT FROM AUTHOR]

In this paper, sources of mercury deposition to the Tampa area (Florida, USA) are investigated by analysis of one year (March 2000–March 2001) of daily wet deposition data. HYSPLIT back-trajectory modeling was performed to assess potential source locations for high versus low concentration events in data stratified by precipitation level. Positive matrix factorization (PMF) was also applied to apportion the elemental compositions from each event and to identify sources. Increased total mercury deposition was observed during summer months, corresponding to increased precipitation. However, mercury concentration in deposited samples was not strongly correlated with precipitation amount. Back-trajectories show air masses passing over Florida land in the short (12 h) and medium (24 h) term prior to deposition for high mercury concentration events. PMF results indicate that eleven factors contribute to the deposited elements in the event data. Diagnosed elemental profiles suggest the sources that contribute to mercury wet deposition at the study site are coal combustion (52% of the deposited mercury mass), municipal waste incineration (23%), medical waste incineration (19%), and crustal dust (6%). Overall, results suggest that sources local to the county and in Florida likely contributed substantially to mercury deposition at the study site, but distant sources may also contribute. [ABSTRACT FROM AUTHOR]

The present paper concerns the study of atmospheric deposition of heavy metals, using a carpet-forming-moss species ( Hypnum cupressiforme ) as a bioindicator. It provides a complementary method to evaluate elemental deposition from the atmosphere to terrestrial systems. Compared with conventional precipitation analysis, it is an easier and cheaper method that ensures a high sampling density over the monitored area. The moss samples were collected over the whole territory of the country by following, more or less, a systematic sampling scheme, which is often used in environmental studies because it is convenient to implement in field campaigns, often providing good precision and complete coverage of the target population compared with random sampling. The 2010/2011 ICP vegetation moss survey data were used in this study. The unwashed, dried samples were digested completely by the microwave digestion method. The concentration ( C ) of selected trace metals (As, Cr, Cu, Ni, V and Zn) and conservative metals (Al, Li and Fe) were determined by ICP-AES and AAS (Cd and As) methods. To characterize the natural and the anthropogenic pattern of heavy metal deposition throughout the whole territory, the normalization process using lithium as a normalizing element was carried out on the C data for 11 elements of 44 moss samples. The obtained data set was used to compensate the natural variability of trace metals, so that the anthropogenic metal contributors could be detected and quantified. Descriptive statistics and multivariate analyses were used for the statistical treatment of the normalized concentration ( NC ) data using the MINITAB 17 software package. The statistical parameters of the NC data are discussed. The level of contamination was evaluated by calculating the enrichment factors, whereas the most probable local anthropogenic emitter sources were identified. The statistical analysis of NC data demonstrated that the normalization process is useful for evaluating the relative contributions of anthropogenic and natural sources of elemental deposition from the atmosphere to terrestrial systems, when the main pollution sources are from fine dust particles. [ABSTRACT FROM AUTHOR]

Heavy metals that are built-up on urban impervious surfaces such as roads are transported to urban water resources through stormwater runoff. Therefore, it is essential to understand the predominant pathways of heavy metals to the build-up on roads in order to develop suitable pollution mitigation strategies to protect the receiving water environment. The study presented in this paper investigated the sources and transport pathways of manganese, lead, copper, zinc and chromium, which are heavy metals commonly present in urban road build-up. It was found that manganese and lead are contributed to road build-up primarily by direct deposition due to the re-suspension of roadside soil by wind turbulence, while traffic is the predominant source of copper, zinc and chromium to the atmosphere and road build-up. Atmospheric deposition is also the major transport pathway for copper and zinc, and for chromium, direct deposition by traffic sources is the predominant pathway. [ABSTRACT FROM AUTHOR]

Understanding the characteristics of the size distribution of ambient black carbon (BC) in distinct environments is critical because the influence of BC aerosols on climate, visibility, and human health depends strongly on the distribution of BC aerosols over the particle size spectrum. In this study, a novel method for determining the mass size distribution of BC in atmospheric aerosols was developed. This size-segregation method relies on measuring BC in parallel using two aethalometers, one of which is used to measure the total BC (BC T ) mass concentration as a reference level and the other is used to measure the BC (BC i ) mass concentration for BC sizes below specific particle sizes that are selected using a size cut-off inlet. In this study, this method was applied to measure BC in atmospheric samples at an urban traffic site. The aethalometers were operated continually from December 15, 2012 to January 31, 2013, and from February 15, 2013 to March 31, 2013. The measurement results presented in this paper are for the diurnal variation patterns, average concentrations, mass fractions, and size distributions of BC aerosols. The results indicate that BC T mass concentration is approximately 2.8 μg m−3 in the Taipei urban area. The levels of BC at this sampling site were affected markedly by traffic emission levels and local wind speed. At the sampling site, the average BC2.5/BC T , BC1.0/BC T , BC0.5/BC T , BC0.25/BC T , and BC0.1/BC T were 0.96 ± 0.04, 0.92 ± 0.07, 0.89 ± 0.04, 0.73 ± 0.10, and 0.18 ± 0.08, respectively. The results indicate that approximately 90% of the BC aerosols were smaller than 0.5 μm, that most of the BC aerosols (55%) were in the size range of 0.1–0.25 μm, and that approximately 18% of the BC aerosols were ultrafine. Moreover, the daily average mass size distribution of BC exhibited a single accumulation mode at 0.16 μm at this sampling site. The mode of the BC mass size distribution at rush hour (9 AM) was only 0.14 μm, which is smaller than the daily average. Moreover, the mode of the BC mass size distribution at an early morning hour (3 AM) was 0.18 μm, and a minor coarse mode was also observed during this period. The results further revealed that the geometric diameter (D pg) of the BC aerosols varied between 0.14 and 0.22 μm and the geometric standard deviation (σ g ) of these BC aerosols ranged between 1.4 and 2.3 during the sampling period. Because BC exhibits extremely low chemical reactivity; the size distribution of BC in the atmosphere does not change substantially except through coagulation. [ABSTRACT FROM AUTHOR]

Abstract: The North Atlantic Oscillation (NAO) has been identified as one of the atmospheric patterns which mostly influence the temporal evolution of precipitation and temperature in the Mediterranean area. Recently, the Western Mediterranean Oscillation (WeMO) has also been proposed to describe the precipitation variability in the eastern Iberian Peninsula. This paper examines whether the chemical signature and/or the chemical deposition amounts recorded over NE Iberian Peninsula are influenced by these climatic variability patterns. Results show a more relevant role of the WeMO compared to NAO in the deposition of either marine (Cl−, Na+, Mg2+) or anthropogenic pollutants (H+, NH4 +, NO3 − and SO4 2−). A cluster classification of provenances indicated that in winter (December to March) fast Atlantic air flows correspond to positive WeMO indices, while negative WeMOi are associated to Northeastern and Southwestern circulations. The negative phase of WeMO causes the entry of air masses from the Mediterranean into the Iberian Peninsula, that are enriched with marine ions and ions of anthropogenic origin (NH4 +, NO3 − and SO4 2−). For these later, this suggests the advection over the Mediterranean of polluted air masses from southern Europe and the scavenging and deposition of this pollution by precipitation during the WeMO negative phases. This will carry transboundary pollutants to the NE Iberian Peninsula. However, local pollutants may also contribute, as precipitation events from the Mediterranean and the Atlantic (associated to both WeMO phases) may incorporate emissions that accumulate locally during the winter anticyclonic episodes typical of the region. [Copyright &y& Elsevier]

Abstract: Tritium is a radioisotope of hydrogen that exists naturally in the environment and may also be released through anthropogenic activities. It bonds readily with hydrogen and oxygen atoms to form tritiated water, which then cycles through the hydrosphere. This paper seeks to model the migration of tritiated species throughout the environment – including atmospheric, river and coastal systems – more comprehensively and more consistently across release scenarios than is currently in the literature. A review of the features and underlying conceptual models of some existing tritium release models was conducted, and an underlying aggregated conceptual process model defined, which is presented. The new model, dubbed ‘Tritium Environmental Release Model’ (TERM), was then tested against multiple validation sets from literature, including experimental data and reference tests for tritium models. TERM has been shown to be capable of providing reasonable results which are broadly comparable with atmospheric HTO release models from the literature, spanning both continuous and discrete release conditions. TERM also performed well when compared with atmospheric data. TERM is believed to be a useful tool for examining discrete and continuous atmospheric releases or combinations thereof. TERM also includes further capabilities (e.g. river and coastal release scenarios) that may be applicable to certain scenarios that atmospheric models alone may not handle well. [Copyright &y& Elsevier]

Abstract: Recently, biomagnetic monitoring of tree leaves has proven to be a good estimator for ambient particulate concentration. This paper investigates the usefulness of biomagnetic leaf monitoring of crown deposited particles to assess the spatial PM distribution inside individual tree crowns and an urban street canyon in Ghent (Belgium). Results demonstrate that biomagnetic monitoring can be used to assess spatial PM variations, even within single tree crowns. SIRM values decrease exponentially with height and azimuthal effects are obtained for wind exposed sides of the street canyon. Edge and canyon trees seem to be exposed differently. As far as we know, this study is the first to present biomagnetic monitoring results of different trees within a single street canyon. The results not only give valuable insights into the spatial distribution of particulate matter inside tree crowns and a street canyon, but also offer a great potential as validation tool for air quality modelling. [Copyright &y& Elsevier]

During the spring of 2010, comprehensive in situ measurements were made for the first time on a small atoll (Dongsha Island) in the northern South China Sea (SCS), a key region of the 7-SEAS (the Seven South East Asian Studies) program. This paper focuses on characterizing the source origins, transport processes, and vertical distributions of the Asian continental outflows over the region, using measurements including mass concentration, optical properties, hygroscopicity, and vertical distribution of the aerosol particles, as well as the trace gas composition. Cluster analysis of backward trajectories classified 52% of the air masses arriving at ground level of Dongsha Island as having a continental origin, mainly from northern China to the northern SCS, passing the coastal area and being confined in the marine boundary layer (0–0.5 km). Compared to aerosols of oceanic origin, the fine mode continental aerosols have a higher concentration, extinction coefficient, and single-scattering albedo at 550 nm (i.e., 19 vs. 14 μg m−3 in PM2.5; 77 vs. 59 Mm−1 in βe; and 0.94 vs. 0.90 in ω , respectively). These aerosols have a higher hygroscopicity (f at 85% RH = 2.1) than those in the upwind inland regions, suggesting that the aerosols transported to the northern SCS were modified by the marine environment. In addition to the near-surface aerosol transport, a significant upper-layer (3–4 km) transport of biomass-burning aerosols was observed. Our results suggest that emissions from both China and Southeast Asia could have a significant impact on the aerosol loading and other aerosol properties over the SCS. Furthermore, the complex vertical distribution of aerosols-coinciding-with-clouds has implications for remote-sensing observations and aerosol–cloud–radiation interactions. [ABSTRACT FROM AUTHOR]

Beryllium-7 is a potentially powerful tracer of soil erosion, but information on 7Be atmospheric deposition and associated soil inventories on the Loess Plateau of China is not readily available. In the study reported in this paper, we measured the 7Be inventories in undisturbed soil at different sampling times on the northern Loess Plateau of China for three years, between 2010 and 2012, and estimated the 7Be deposition fluxes and the daily 7Be inventories in undisturbed soil. The annual 7Be deposition fluxes during this period varied between 1303 ± 119 and 2222 ± 147 Bq m−2, with a mean of 1759 ± 416 Bq m−2. There is a marked seasonality for the 7Be deposition fluxes with the maximum in summer, approximately 50% to the annual deposition flux, and the minimum in winter, approximately 5% to the annual deposition flux. Precipitation amounts can explain more than 70% of the variation in 7Be deposition flux. 7Be deposition in the form of dustfall, dew and frost make a significant contribution to the 7Be deposition flux in the study region. The daily 7Be inventories in undisturbed soil varied markedly through time and ranged between 89.2 and 941.8 Bq m−2 with a mean of 392 ± 210 Bq m−2. They demonstrated a unimodal distribution over the year, with the highest values in August or September and the lowest in late winter or early spring. [ABSTRACT FROM AUTHOR]