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The chemical composition of the atmospheric bulk deposition is a good indicator of atmospheric pollution and air quality. Bulk deposition is a collective term for wet deposition in the forms of rain, snowfall, fog, hail, or ice crystals and dry deposition of atmospheric chemical components mainly under the gravitational settling. The objective of the study was to quantitatively determine rainwater quality parameters, using standard procedures, in selected areas of Sri Lanka. Analysis of weekly sampling of bulk deposition in three sampling sites in Divulapitiya, Kandy, and University of Peradeniya (UOP) of Sri Lanka performed for a period of 24 weeks from 08th of February 2022 to 19th of July 2022 indicated that the three sites had 16.7%, 8.7%, and 8.3% dry-only depositions, respectively; with rainfall levels of 30.2 ± 37.4 mm, 30.6 ± 32.6 mm, and 33.7 ± 39.8 mm; and volume-weighted mean (VWM) pH values of 6.23, 6.29, and 6.47, respectively. Acidic deposition events below pH 5.60 level were not recorded from any site. Chloride (Cl−) was determined to be the predominant anion, and the VWM of anions varied in the order of NO3− < SO42− < Cl− in all three sites. Among trace metals investigated, Fe, Zn, and Al were predominant. Moreover, a very strong positive correlation for conductivity, total dissolved solids, and salinity among each parameter, was observed in the Pearson correlation analysis for all sites. Divulapitiya area showed low air pollution levels with respect to chemical and physical parameters determined in the study as compared to Kandy and UOP areas. Possible causes for the results would be vehicular, constructional, and industrial emissions, and natural geographical factors. [ABSTRACT FROM AUTHOR]

The composition of atmospheric precipitation, an important criterion considered to account for air pollution, is usually determined with respect to wet precipitation and dry precipitation, or as bulk deposition in combined form. Although rainwater quality should be continuously monitored in order to understand the extent of air pollution, such investigation lacks attention in Sri Lanka. This study was thus aimed to determine the composition of bulk deposition collected weekly for a period of eleven months from February to December 2019, in three sampling locations; namely the University of Peradeniya (UOP), Kandy City Central (KCC) and Polgolla. Parameters quantitatively determined, rainfall, pH, conductivity, salinity, total dissolved solids (TDS), hardness, anions: Cl−, NO3−, SO42−, F−, PO43− and trace metals: Zn, Fe, Al, Mn, Cu, Pb, Cr, using standard analytical methods indicated that the KCC site showed the overall highest degree of air pollution followed by UOP and Polgolla sites. Nevertheless, no acid rain occurrences were observed during the sampling period in any of the three sites according to pH measurements. Anions of bulk deposition showed the sequence Cl−> SO42− > NO3−in all three sites with Cl−and SO42- being dominant anions. Furthermore, trace metals of bulk deposition showed the sequence, Zn > Fe > Al > Mn > Cu > Pb, in all three sites. Bulk precipitation data analyzed using Pearson correlation showed high positive significant correlations between conductivity and salinity, conductivity and TDS, and salinity and TDS, among all water quality parameters. Among trace metals, the highest positive significant correlation was found to be between Fe and Mn at the UOP Site. The highest positive significant correlation was between Al and Zn at the KCC site. No correlation between trace metals was found at the Polgolla Site.

The chemical composition of bulk deposition is an important aspect of assessing ambient air pollution. It contributes significantly to the removal of pollutants from the atmosphere and their transfer to other ecosystems. Thus, it is a reliable determinant of environmental chemistry. Therefore, bulk deposition can be considered useful for tracking the migration path of substances from different sources. The aim of the study carried out at five measurement points in Zabrze and Bytom was to assess the content of selected physico-chemical parameters in bulk deposition. Samples were collected continuously from November 2019 to November 2020. In the collected samples the following were determined: COD, pH, conductivity, dissolved organic carbon, inorganic carbon and total carbon; inorganic anions (Cl-, SO42-, NO3-, NO2-, Br-, PO43-) and cations (Li+, Mg2+, Ca2+, Na+, K+, NH4+), metals and metalloids (Mn, Ni, Co, Cu, Zn, As, Cd, Pb, Cr, and Fe), and carboxylic acids (formic, acetic, oxalic). The obtained test results were statistically processed using Excel, and the normality of data distribution was verified by Shapiro-Wilk test. The results show that pollutants transported in the atmosphere and introduced with precipitation in the Zabrze and Bytom areas are a significant source of area pollution of the region.

This paper present seasonal variation in the equivalent concentration (BaPeq) of PAHs in order to assess the potential cancer risk for two different groups of residents via ingestion, dermal contact and inhalation pathways. The possible ecological risk caused by PAH atmospheric deposition based on risk quotient was also estimated. A bulk (total, wet and dry) deposition and PM10 particle fraction (particles with an equivalent aerodynamic diameter < 10 µm) were collected from June 2020 to May 2021 at an urban residential location in the northern part of Zagreb, Croatia. The monthly average of total equivalent BaPeq mass concentrations of PM10 varied from 0.057 ng m−3 in July to 3.656 ng m−3 in December; the annul ∑BaPeq average was 1.348 ng m−3. In bulk deposition, ∑BaPeq mass concentrations varied from 1.94 to 57.60 ng L−1. In both investigated media, BaP had the highest contribution in carcinogenic activity. For PM10 media, dermal absorption implied the greatest potential cancer risk, followed by ingestion and inhalation. For bulk media, a moderate ecological risk for BaA, BbF and BaP was observed according to the risk quotient approach. [ABSTRACT FROM AUTHOR]

Abstract In this paper a manufacturing process is introduced to treat the bulk surfaces of surfaces via graphite powder blasting to directly produce an adherent layer of graphene. Subsequently, the study aims to correlate optical, thermal and electrochemical modifications with treatment parameters such as blasting pressure, nozzle distance and number of passes. After the treatment, the target surface has enhanced spectral, thermal and electrochemical properties because of the graphene’s turbostratic nature to adhesion to its surface. The thermal stability performance showed a consistent 5% increase relative to a bare aluminum substrate. A two-fold increase in corrosion resistance is seen in the sample compared to bare aluminum while diffuse absorbance values enhancement is around three-fold. This proposed manufacturing method provides straightforward and effective treatment at various degrees of automation. Since the deposited graphene substrate can cover a large area, it can be applied as a final layer on thermal collectors, PV panels and for other applications. It is possible to adopt this process to other well-established treatment plants without requiring high investments in the overhead expenses.

In recent years, additive manufacturing (AM) has gained prominence in rapid prototyping and production of structural components with complex geometries. Magnesium alloys, which have a strength-to-weight ratio that is superior compared with steel and aluminum alloys, have shown potential in lightweighting applications. However, commercial beam-based AM technologies have limited success with magnesium alloys due to vaporization and hot cracking. Therefore, as an alternative approach, we propose the use of a near net-shape solid-state additive manufacturing process, additive friction stir deposition (AFSD), to fabricate magnesium alloys in bulk. In this study, a parametric investigation was performed to quantify the effect of process parameters on AFSD build quality including volumetric defects and surface quality in magnesium alloy AZ31B. In order to understand the effect of the AFSD process on structural integrity in the magnesium alloy AZ31B, in-depth microstructure and mechanical property characterization was conducted on a bulk AFSD build fabricated with a set of acceptable process parameters. Results of the microstructure analysis of the as-deposited AFSD build revealed bulk microstructure similar to wrought magnesium alloy AZ31 plate. Additionally, similar hardness measurements were found in AFSD build compared with control wrought specimens. While tensile test results of the as-deposited AFSD build exhibited a 20% drop in yield strength (YS), nearly identical ultimate strength was observed compared with the wrought control. The experimental results of this study illustrate the potential of using the AFSD process to additively manufacture Mg alloys for load bearing structural components with achieving wrought-like microstructure and mechanical properties. [ABSTRACT FROM AUTHOR]

The chemical composition of bulk deposition is an important aspect of assessing ambient air pollution. It contributes significantly to the removal of pollutants from the atmosphere and their transfer to other ecosystems. Thus, it is a reliable determinant of environmental chemistry. Therefore, bulk deposition can be considered useful for tracking the migration path of substances from different sources. The aim of the study carried out at five measurement points in Zabrze and Bytom was to assess the content of selected physico-chemical parameters in bulk deposition. Samples were collected continuously from November 2019 to November 2020. In the collected samples the following were determined: COD, pH, conductivity, dissolved organic carbon, inorganic carbon and total carbon; inorganic anions (Cl-, SO4 2-, NO3 -, NO2 -, Br-, PO4 3-) and cations (Li+, Mg2+, Ca2+, Na+, K+, NH4 +), metals and metalloids (Mn, Ni, Co, Cu, Zn, As, Cd, Pb, Cr, and Fe), and carboxylic acids (formic, acetic, oxalic). The obtained test results were statistically processed using Excel, and the normality of data distribution was verified by Shapiro-Wilk test. The results show that pollutants transported in the atmosphere and introduced with precipitation in the Zabrze and Bytom areas are a significant source of area pollution of the region. [ABSTRACT FROM AUTHOR]

This paper present seasonal variation in the equivalent concentration (BaPeq) of PAHs in order to assess the potential cancer risk for two different groups of residents via ingestion, dermal contact and inhalation pathways. The possible ecological risk caused by PAH atmospheric deposition based on risk quotient was also estimated. A bulk (total, wet and dry) deposition and PM10 particle fraction (particles with an equivalent aerodynamic diameter < 10 µm) were collected from June 2020 to May 2021 at an urban residential location in the northern part of Zagreb, Croatia. The monthly average of total equivalent BaPeq mass concentrations of PM10 varied from 0.057 ng m−3 in July to 3.656 ng m−3 in December; the annul ∑BaPeq average was 1.348 ng m−3. In bulk deposition, ∑BaPeq mass concentrations varied from 1.94 to 57.60 ng L−1. In both investigated media, BaP had the highest contribution in carcinogenic activity. For PM10 media, dermal absorption implied the greatest potential cancer risk, followed by ingestion and inhalation. For bulk media, a moderate ecological risk for BaA, BbF and BaP was observed according to the risk quotient approach.

The geochemically conjugate series of soils (Albic Podzol – Albic Podzol Gleyc – Hystosol) formed on an undulating glaciolacustrine plain in the middle taiga of Karelia was investigated. Surveys for redox conditions showed them to vary from oxidizing in automorphic soils to reducing in soils occupying accumulation-favoring locations. The geochemical coefficients descriptive of the features of accumulation and directions of migration in the studied soils were calculated and analyzed. The distribution of silicic acid and a majority of sesquioxides inside the profile of the studied soils is typical of podzols. The podzolic horizons of the soils occupying interstitial positions have a faster outmigration of elements than in automorphic soils, while their Al-Fe-humic horizons accumulate aluminum, iron, titanium and phosphorus. All the soils are deficient in a majority of microelements as compared to their background levels; very low concentrations were determined for nickel, cobalt and manganese. The content of copper and sometimes zinc is at the background level. The distribution of the studied elements across the soil profile follows the accumulation-eluviation-illuviation pattern, but the scope of variation in the migration of elements varies among topographic positions. In well-drained locations microelements are quite monotonously distributed through the lower part of the soil profile, while soils in transitional landscapes have a higher differentiation of microelements. The differentiation of the catena through lateral migration is of the transient eluviation type, i.e. soils in lower-lying positions are poorer in the studied elements than soils in automorphic positions. This pattern is due to the natural characteristics of the area: low surface slope, homogeneous sandy parent material, low humus content in soil.

Study region: The current study evaluates the isotopic and chemical compositions of rainfall from central to leeward Hawaiʻi Island, an area characterized by the interactions of Pacific trade wind flow with two 4,000-meter high mountains as well as one of the largest natural emitters of sulfur dioxide on the planet. Study focus: Our study collected cumulative rainfall samples at regular intervals over a 28-month period from 20 stations spanning a range of elevations across this region and determined average isotopic and dissolved ion compositions in those samples. The study period included an extreme weather event (Hurricane Lane), a major volcanic eruption at Kīlauea in 2018, and the nearly complete cessation of long-term volcanic emissions following that eruptive event. New hydrological insights: to the Region Consistent with previous literature, results show long-term variability through our establishment of an enhanced local meteoric water line (LMWL) for West Hawaiʻi. We hypothesize the two LMWL represent ends of a spectrum, due to the variability in atmospheric and climate processes in this region. Additionally, results of stable isotope compositions and bulk ion deposition highlight how extreme events, such as volcanic eruptions and hurricanes, can affect the chemistry of precipitation. Sulfate concentrations in bulk precipitation decreased by a mean of 70 % (p = 0.032) after the 2018 Kīlauea eruption ceased. The results from this study can be used to better quantify and characterize precipitation, which is the ultimate source of Hawai‘i’s groundwater.

From 2011 to 2019, mercury (Hg) stores and fluxes were studied in the small forested catchment Lesní potok (LES) in the central Czech Republic using the watershed mass balance approach together with internal measurements. Mean input fluxes of Hg via open bulk deposition, beech throughfall and spruce throughfall during the periodwere 2.9, 3.9 and 7.6 μg m−2 year−1, respectively. These values were considerably lower than corresponding deposition Hg fluxes reported in the early years of the 21st century from catchments in Germany. Current bulk precipitation inputs at unimpacted Czech mountainous sites were lower than those in Germany. The largest Hg inputs to the catchment were via litterfall, averaging 22.6 and 17.8 μg m−2 year−1 for beech and spruce stands. The average Hg input, based on the sum of mean litterfall and throughfall deposition, was 23.0 μg m−2 year−1, compared to the estimated Hg output in runoff of 0.5 μg m−2 year−1, which is low compared to other reported values. Thus, only ~2% of Hg input is exported in stream runoff. Stream water Hg was only weakly related to dissolved organic carbon (DOC) but both concentrations were positively correlated with water temperature. The estimated total soil Hg pool averaged 47.5 mg m−2, only 4% of which was in the O‐horizon. Thus Hg in the O‐horizon pool represents 72 years of deposition at the current input flux and 3800 years of export at the current runoff flux. Age‐dating by 14C suggested that organic soil contains Hg from recent deposition, while mineral soil at 40–80 cm depth contained 4400‐year old carbon, suggesting the soil had accumulated atmospheric Hg inputs through millennia to reach the highest soil Hg pool of the soil profile. These findings suggest that industrial era intensification of the Hg cycle is superimposed on a slower‐paced Hg cycle during most of the Holocene. [ABSTRACT FROM AUTHOR]

The present study determines the levels of n-alkanes in atmospheric wet deposition at an urban site in the Indo-Gangetic Plain, Delhi, during monsoon and non-monsoon periods in 2021. The n-alkane homologs (C 10 –C 33) were determined in wet deposition, which included wet-only and bulk samples. The average total n-alkanes were found to be 56.0 ± 16.7 and 439.4 ± 150.8 μg/L in wet-only samples, whereas, 149.6 ± 46.4 and 454.9 ± 108.4 μg/L in bulk samples during monsoon and non-monsoon periods, respectively. The low molecular weight n-alkanes (C 10 –C 25) exhibited no odd-even predominance in wet-only and bulk depositions during monsoon and non-monsoon periods. However, the high molecular weight n-alkanes (>C 25) showed odd-even predominance during the non-monsoon period. The molecular distribution patterns of n-alkanes indicated possible emissions from bacteria, fossil-fuel combustion, direct volatilization of unburnt fuels, biogenic sources, and other anthropogenic activities. A health risk assessment for n-alkanes revealed the higher susceptibility of children via dermal and oral exposure. The Hazard Index for the exposure of n-alkanes through atmospheric wet deposition was <1, i.e., within the acceptable limit. The Carbon Preference Index (CPI) and wax n-alkanes (WNA)%, supported the prevalence of mixed emission sources with higher contributions from anthropogenic activities. Five sources of n-alkanes were identified using the positive matrix factorization (PMF) model, i.e., gasoline vehicles + fuel evaporation, biogenic, biogenic + diesel exhaust, road dust, and mixed, contributing ∼30 %, 11 %, 26 %, 17 %, and 16 % respectively. The Concentration Weighted Trajectory (CWT) analysis revealed that n-alkanes in wet-only and bulk samples were contributed by different local, regional, and long-range transport of air pollutants. • The first study in the Indian context to investigate n-alkane homologs in wet deposition. • The molecular distribution of n-alkanes suggested their prevalent emissions from anthropogenic and biogenic sources. • The Hazard Index of n-alkanes for exposure through atmospheric wet deposition was within the acceptable limit (<1). • The major sources of n-alkanes were gasoline vehicles, fuel evaporation, biogenic, diesel exhaust, road dust, and mixed. [ABSTRACT FROM AUTHOR]

Abstract While the ongoing increases in the deposition of atmospheric nitrogen (N) in China have attracted ever more attention, to date there has been little research in N deposition in inland aquatic ecosystems. In this study, we quantified the bulk and dry atmospheric N deposition around the Dongting Lake, which is connected to the Yangtze River and is the second largest freshwater lake in China. Bulk N deposition averaged 48.0 kg N ha−1 yr−1, of which ammonium (NH 4 N), nitrate (NO 3 N), and dissolved organic nitrogen (DON) accounted for 41.6%, 35.1%, and 23.3%, respectively. Dry N deposition averaged 27.0 kg N ha−1 yr−1, and was dominated by NH 3. Bulk N deposition was higher in spring and summer than in autumn and winter at the sites around the lake because of the high precipitation. NH 3 deposition was the highest in spring and summer due to fertilization, and NO x deposition was the highest in winter because of the combustion of coal for domestic heating. The concentrations of NH 3 significantly decreased with the concentration of NH 4 N, indicating below-cloud scavenging and local sources. The concentrations of NO x and NO 3 N were not correlated, indicating long-distance transfer of NO x. Bulk N deposition in our study was generally twice that reported in other studies, even when only inorganic N species in bulk deposition were considered. Total N deposition averaged 75.0 kg N ha−1 yr−1, which was much higher than that reported in other studies. Both N deposited directly into the lake and N deposited across the lake basin that was subsequently transported to the lake in runoff could enrich the N concentration of the lake water and increase the gross primary productivity (GPP). Our results highlighted the importance of integrated management that includes both aquatic and atmospheric systems at either the lake basin scale or regional scale, rather than at the individual lake-scale. Graphical abstract Image 1 Highlights • Total N deposition was much higher than that reported in other studies around the Dongting Lake. • DON deposition, which usually be ignored, is a significant contributor. • Potential eutrophication effects of N loading to the Dongting Lake from atmospheric N deposition should be re-evaluated. [ABSTRACT FROM AUTHOR]

Soil, street dust, and bulk deposition (dry and wet deposition) were collected in the Metropolitan Area of Buenos Aires (MABA), Argentina, to assess the polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) pollution and the potential risks to human health. Compared with other countries, the mean concentration of PAHs and PCBs in surface soils, street dust and bulk deposition of MABA were at a low or moderate level. Average PAHs and PCBs concentrations in bulk deposition (5.7 ± 5.1 and 0.41 ± 0.25 µg g−1, respectively) were five and ten times higher than those of soil (1.08 ± 0.98 and 0.02 ± 0.01 µg g−1) and street dust (1.2 ± 0.95 and 0.04 ± 0.03 µg g−1), respectively. Different compositional profiles, observed in the three matrices for both groups of contaminants, could be attributed to dissimilar source contribution, partition processes between gas and particulate phases, and transformation. The most contaminated bulk deposition presented higher values for cancer and non-cancer risks relative to soil and street dust. In all matrices, non-carcinogenic risks were below the safety threshold (HI < 1). Regarding carcinogenic risks, exposure to both bulk deposition and soil indicated a moderated potential for cancerous development (Incremental lifetime cancer risk ~ 3.0 × 10−6). [ABSTRACT FROM AUTHOR]

While atmospheric deposition plays a vital role in cleaning air pollutants, it also supplies toxic heavy metals and metalloids (MMs) to the receiving terrestrial and aquatic ecosystems and threatens human health through food chains. To characterize the input of atmospheric deposition to agricultural soils, bulk rain samples were collected on an event basis at a rural site in the North China Plain during 2016–2020. The results show that higher concentrations of MMs in bulk rain samples were associated with western and southern air masses passing polluted areas. In addition, the annual deposition flux of MMs tends to decline during the study period, coinciding with the inter-annual variations of particulate matter rather than the precipitation amounts. Of note, the deposition flux of MMs that exist entirely in fine particles declined significantly compared to those that exist in coarse particulate form, indicating that the clean air actions implemented in recent years were highly effective in reducing ambient MMs from anthropogenic emissions. The positive matrix factorization receptor model was also applied to the whole data set for bulk depositions and five sources were identified as agricultural (biomass burning and soil), dust, coal combustion, industrial and traffic emissions. These factors contributed 41%, 24%, 21%, 9% and 5% of the chemical components in bulk depositions, respectively. Future control strategies should tighten the emissions from combustion and soil/dust in the North China Plain to protect agriculture from atmospheric MMs depositions.

Major ions and trace metals concentrations of bulk precipitation collected at a suburban area of Northwest of Spain were investigated by using a sedimentary particles sampler and a tipping bucket rain gauge collectors. Bulk precipitation samples were analysed for pH, electro-conductivity, and concentrations of major ions and trace metals. Results achieved using both collectors were compared to know the possibility of indistinguishable use of both collectors in deposition networks. Statistical analysis (analysis of variance ANOVA, multiple range test and regression analysis) of rainfall amount and major ions and trace metals concentrations achieved by using both collectors was performed. Although some significant seasonal differences were observed for Ba, Co and Zn concentrations, ANOVA multiple range tests revealed no significant difference (p < 0.05) when using both collectors. Thus, sedimentary particles sampler and tipping bucket rain gauge collectors can be used interchangeably in deposition networks. [ABSTRACT FROM AUTHOR]

This study aimed to assess the chemical composition of the rainwater in three areas of different environmental impact gradients in Southern Brazil using the receptor model EPA Positive Matrix Factorization (EPA PMF 5.0). The samples were collected in a bulk sampler, from October 2012 to August 2014, in three sampling sites along with the Sinos River Basin: Caraá, Taquara, and Campo Bom. The major ions NH4+, Na+, K+, Ca2+, Mg2+, F−, Cl−, NO3−, SO42−, and pH were analyzed, as well as identify the main emission sources. The most abundant cations and anions were Ca2+, Na+, Cl−, and SO42−, respectively. The mean pH value in the Sinos River Basin during the study period was 6.07 ± 0.49 (5.13-7.05), which suggests inputs of alkaline species into the atmosphere. The most important neutralizing agents of sulfuric and nitric acids in the Sinos River Basin are Ca2+ (NF = 1.36) and NH4+ (NF = 0.57). The source apportionment provided by the EPA PMF 5.0 resulted in four factors, which demonstrate the influence of anthropogenic and natural sources, in the form of (a) industry/combustion of fossil fuels (F− and SO42−), (b) marine contribution (Na+ and Cl−), (c) crustal contribution (K+, Ca2+, and NO3−), and (d) agriculture/livestock (NH4+). Therefore, this study allows a more appropriate understanding of factors that contribute to rainwater chemical composition and also to possible changes in air quality. [ABSTRACT FROM AUTHOR]

Base cations, such as potassium (K + ), calcium (Ca 2+ ) and magnesium (Mg 2+ ), are essential nutrients for plant growth and their atmospheric inputs can buffer the effect of acid deposition by nitrogen (N) and sulphur (S) compounds. However, the spatial variation in atmospheric deposition of these base cationic nutrients is less understood compared with N and S deposition. By synthesizing bulk deposition data for K + , Ca 2+ and Mg 2+ , we assessed their annual rates and spatial characteristics at 34 forested sites across China. Our synthesis showed relatively high levels of bulk deposition of base cationic nutrients in China's forests, being an order of magnitude higher than in the USA and Europe. On average, K + , Ca 2+ and Mg 2+ accounted for 13%, 72% and 15% of the bulk deposition of base cationic nutrients, respectively. Surprisingly, base cation deposition was lower at sites near semi-arid regions compared with sites in eastern and southern China, which were far from semi-arid regions. Moreover, elevated base cation deposition was associated with urban hotspots, exhibiting a significant power-law increase with closer distance to the nearest large cities. We estimated that on average base cationic nutrients neutralized a significant proportion (76%) of the potential acid load due to acid deposition. Our findings suggest that in China there is considerable anthropogenic alteration of the regional cycling of base cationic nutrients, which plays an important role in counteracting the risk of soil acidification and base cation depletion in forest ecosystems, especially in the southern regions. [ABSTRACT FROM AUTHOR]

This study provides an analysis of a five-year time series chemical composition of the bulk deposition (2009–2013), collected within a farm surrounded by industrial and urban settlements in a semi-rural area of the Po Valley, with the aim of characterizing potential emission sources affecting precipitation composition at the site. Most monitoring efforts in this region, recognized as one of the most polluted in the world both due to the intense industrialisation and urbanisation as well as to frequent air stagnation conditions, are presently devoted more to gaseous and particulate pollutants than to precipitation chemistry. The bulk deposition samples were very concentrated in chemical species, both acidic and alkaline, high compared to other polluted sites in the world and to locations in the same district. The mean ions concentrations (in μeq l−1) are: NO3− (243) > SO42− (220) > PO43− (176) > Cl− (153) > NO2− (29) > F− (2.6); NH4+ (504) > Ca2+ (489) > K+ (151) > Na+ (127) > Mg2+ (127). pH data shows a trend toward slightly alkaline conditions attributed to the large presence of ammonium and crustal elements, in spite of high concentrations of nitrates and sulphates. The relevant concentrations of Ca2+ and Mg2+ further suggests that these alkaline conditions might be due to the correspondingly significant concentrations of carbonates/bicarbonates in our dataset. While back-trajectories analysis suggests the stronger importance of local resuspension over long-range transport, statistical analyses on ion composition highlight the key role exerted by agricultural activity, especially in the case of NH4+, K+, Ca2+ and PO43− (especially linked to fertilisation practices and soil resuspension due to mechanical operations). Apart from Na+ and Cl− ions which correlate well as expected, indicating their likely common origin from marine salt, the identification of the origin of the other ions is very complex due to the contribution of diverse local sources, such as industrial and residential settlements. [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]

Measurements of trace element (As, Cu, Cd, Cr, Ni, Pb, Zn) deposition fluxes were conducted simultaneously in two contrasted environments, i.e., urban and forest, between April 2013 and October 2014. This was the first such project in central Poland, aimed at long-term observations of trace elements in the atmosphere and their distribution, transport, and deposition pattern. The receptor sites were different in terms of local meteorological conditions, emission potential, and distance to major anthropogenic sources. The deposition fluxes of all trace elements showed clear seasonal variations, with relatively higher values in winter than in summer. The main factors affecting interannual differences in concentrations and deposition of trace elements in central Poland were local emission from industrial and commercial sources, and changes in atmospheric conditions (wind speed and direction, boundary layer, precipitation amount, air mass origin). In this study, the impact of regional and long-range transport on trace element deposition was determined using the air back-trajectory cluster analysis. During the summertime of 2013 and 2014, the predominant SW and E advections from regional and remote anthropogenic sources in Europe were responsible for high deposition of Cd, Cr, Pb, Cu, and Zn, whereas during the wintertime of 2013/2014, we observed a significant influence of polluted air masses from southeastern regions. Based on the Pb/Zn ratio, it was found that regional sources significantly influenced the aerosol composition and rainwater chemistry within the study domain. However, the role of a long-range transport of anthropogenic pollutants was also important. In addition, a relatively small difference in the Pb/Zn ratio between both sites (urban 0.26 ± 0.18, forest 0.23 ± 0.17) may suggest (1) very similar contribution of anthropogenic sources and (2) minor importance of atmospheric transformation processes of these metals in the aqueous phase. [ABSTRACT FROM AUTHOR]

Remote sensing technology has great potential to expand the observation of ground-level nitrogen deposition from local monitoring sites to a regional scale, with high spatial and temporal resolutions. A new methodology is developed to estimate the spatial distribution of monthly bulk nitrogen deposition on a regional scale, based on precipitation amounts and HNO 3 and aerosol nitrate (NO 3 − ) columns, derived from OMI NO 2 columns and the relationship of NO 2 , HNO 3 and NO 3 − from MOZART. The accuracy assessment shows that the proposed model has achieved a reasonably high predictive power for monthly NO 3 − -N deposition (slope = 0.96, intercept = 0.35, R = 0.83, RMSE = 0.72) across China. The spatial NO 3 − -N deposition shows a significant gradient from industrial areas to undeveloped regions, ranging from 0.01 to 26.76 kg N ha − 1 y − 1 with an average of 5.77 kg N ha − 1 y − 1 over China during 2010–2012. The bulk NO 3 − -N deposition shows a clear seasonal variation, with high depositions occurring in the warm season (March–November) and peaking in July and August, and low bulk NO 3 − -N deposition appearing in winter (December–February). This study proves for the first time that the atmospheric boundary layer (ABL) HNO 3 and NO 3 − columns and precipitation are powerful to predict the bulk nitrate deposition. [ABSTRACT FROM AUTHOR]