Dry Deposition Samples Research Articles

Dry deposition fluxes, source, and potential ecological impact of amino acids in the Danjiangkou Reservoir of China's South-to-North water transfer project

As a nitrogen source for biological growth, amino compounds can participate in global nitrogen cycle processes and directly impact ecosystems. Dry deposition samples were collected from September 2020 to August 2021 from the Danjiangkou Reservoir of the South-to-North Water Transfer Project. The dry deposition characteristics of amino acids in the reservoir area were analyzed, their sources were resolved, and the potential ecological impacts were evaluated. The results showed that the dry deposition flux of dissolved free amino acids was 0.48 kg N ha−1 yr−1 and that of dissolved combined amino acids was 1.09 kg N ha−1 yr−1 in Danjiangkou Reservoir. The dominant amino acid fractions were glutamic acid and aspartic acid. Agricultural activities, coal combustion, and primary biogenic particles influenced the amino acid deposition in the reservoir area. The potential source areas for amino acid deposition mainly influenced the northeast, southwest, northwest, and south of the reservoir. The amounts of amino acids entering the water bodies via dry deposition was 85.72 t N yr−1, contributing 0.83 g C m−2 yr−1 of new production to the reservoir water bodies. To summarize, this research depicted that the potential ecological impact of dry deposition of amino acids on artificial freshwater lakes should not be overlooked.

Transport characteristics of heavy metals in the soil-atmosphere-wheat system in farming areas and development of multiple linear regression predictive model

Heavy metal accumulation in agricultural products has become a major concern. Previous studies have focused on the transport of heavy metals from the soil and their accumulation in crops. However, recent studies revealed that wheat leaves, ears, and awns can also transport and accumulate heavy metals. Wheat grains can be influenced by two sources of heavy metals: soil contamination and atmospheric deposition. To comprehend the transport characteristics of heavy metals in soil, atmospheric deposition, and wheat, 37 samples each for wheat rhizosphere soil, wheat roots, stems, leaves, and grains were collected. Fifteen samples of atmospheric dry deposition and atmospheric wet deposition were collected from Linshu County (northern area), China. Based on the test data, the characteristics of heavy metals and their distribution in the study area were analyzed. Migration patterns of heavy metals in crops from different sources were investigated using Pearson correlation and redundancy analysis. Finally, a predictive model for heavy metals in wheat grains was developed using multiple linear regression analysis. Significant disparities in the distribution of heavy metals existed among wheat roots, stems, leaves, and grains. The coefficient of variation of heavy metals in atmospheric deposition was relatively high, indicating discernible spatial patterns influenced by human activities. Notably, a positive correlation was observed between the concentration of heavy metals in wheat grains and atmospheric deposition of Hg, Cd, and Pb. Conversely, Zn and Ni levels in wheat grains were significantly negatively associated with soil Zn, Ni, pH, and OM content. The contribution of heavy metal elements from different sources varied in their impact on the grain's heavy metal content. Specifically, atmospheric deposition was the primary source of Hg and Pb in wheat grains, while Cd, Ni, Cu, and Zn were predominantly derived from soil. Using a multiple linear regression model, we could accurately predict Hg, Pb, Cd, Ni, Zn, and As concentrations in crop grains. This model can facilitate quantitative evaluation of ecological risk of heavy metals accumulation in crops in the study area.

Assessment of potentially toxic elements (PTEs) in atmospheric dry deposition of Hamedan Metropolis, west of Iran: pollution status, spatiotemporal variation, health risk implications, and source identification.

The present study was designed to assess concentrations, contamination levels, spatiotemporal variations, health hazards and source apportionment of potentially toxic elements (As, Cd, Co, Cr, Cu, Mn, Ni, Pb, Zn, and V) of atmospheric dry deposition (ADD) in Hamedan Metropolis. In so doing, a total of 144 atmospheric dry deposition samples were collected from 12 sites during four seasons in 2023. The concentrations of the analyzed PTEs in dry deposition samples were determined using ICP-OES after samples were digested with acid. The results illustrated that the average contents of As, Cd, Cr, Cu, Ni, Pb, and Zn with 4.52, 0.591, 4.01, 36.5, 42.5, 10.9, 84.6, 69.6, 178, and 3.91mg/kg, respectively, were higher than those in the background samples reported for Iran, which could indicate the anthropogenic origin of these PTEs. The highest quantities of the tested PTEs in various seasons were observed in summer and/or fall samples and their highest amount in various functional regions pertained to the samples collected from the commercial or industrial regions, showing the effect of seasonal changes on emission sources and human inputs. Values of average contamination factor (CF), geo-accumulation index (I-geo), and enrichment factor (EF) ranged from 0.013 to 4.45, - 7.07 to 1.56, and 0.120 to 41.3, respectively, showing 'slight to high' pollution, 'unpolluted to moderately polluted', and 'no enrichment to very severe enrichment' levels, respectively. The pollution load index (PLI) with an average value of 0.680 reflected slight pollution levels in the entire study area. The average hazard index (HI) values of the tested PTEs for the residents were all within the safe limit (< 1). Additionally, the total carcinogenic risk (TCR) values showed that the carcinogenic risk of As, Cr and Ni for both target groups were at an acceptable level. Based on the positive matrix factorization (PMF) model, non-exhaust emissions and natural sources, fossil fuel combustion and industrial emissions, and traffic sources were identified as the primary contributors to ADD pollution, accounting for 26%, 38%, and 36%, of the total pollution respectively. In conclusion, further research is recommended to investigate the source-oriented ecological and health risks associated with atmospheric dry deposition pollution.

Atmospheric deposition studies of microplastics in Central Germany

AbstractEmission of microplastics (MP) to the atmosphere, airborne transport, and subsequent deposition are now recognized. However, the temporal and spatial resolution of data on MP pollution and knowledge of their atmospheric behaviour and fate is still very limited. Hence, we investigated MP wet and dry deposition in Central Germany and examined the role of weather conditions on MP contamination levels. Monthly samples of dry and wet deposition were taken over an eight-month period (05/2019-12/2019) and analysed by micro-Fourier-Transform Infrared spectroscopy (µFTIR) down to 11 μm particle size and one dry deposition sample was subjected to Raman analysis to determine plastic particles down to a size of 0.5 μm. MP in a size range from 11 μm to 130 μm were detected in all wet deposition samples and in 4 out of 8 dry deposition samples by µFTIR. Polypropylene particles were found most frequently and accounted for 62% and 54% of all particles in wet and dry deposition samples, respectively. Over the eight-month period, wet deposition of MP slightly dominated at the study site and comprised 59% of the total MP deposition. The MP mean total (wet + dry) deposition flux (DF) was 17 ± 14 MP m− 2 day− 1. Extensive Raman analyses of an exemplary dry deposition sample revealed additional plastic particles in the extended size range from 1 to 10 μm resulting in a deposition flux of 207 MP m− 2 day− 1. Our results suggest that MP analysis by µFTIR down to 11 μm may underestimate DF at least by an order of magnitude. More comprehensive studies on submicron plastics and nanoplastics are needed to fully assess air pollution by plastic particles.

Risk assessment and source apportionment of available atmospheric heavy metal in a typical sandy area reservoir in Inner Mongolia, China

This study evaluated dry and wet deposition of atmospheric heavy metals (HMs) in a sandy area of Inner Mongolia, China, with the Dahekou Reservoir, Xilin Gol League, adopted as the study area. Monthly monitoring of atmospheric HM dry and wet deposition was conducted over one year (2021 to 2022) at 12 monitoring points, producing 144 dry and wet deposition samples, respectively. The sample contents of eight HMs (Cr, Ni, Pb, Cu, Zn, Mn, As, and Cd) were determined to estimate the fluxes of available forms of heavy metal (AHM) in dry and wet deposition. The potential ecological index (Eri), risk assessment coding (RAC), and ratio of secondary phase to primary phase (RSP) were used to evaluate the impact of atmospheric HM dry deposition on ecological security. Correlation analysis, principal component analysis, and the absolute principal component scores-multiple linear regression (APCS-MLR) receptor model were used to quantitatively analyze the sources of AHMs in atmospheric dry and wet deposition. The results showed that the study area experienced annual dry and wet deposition fluxes of AHMs of 1712.59 kg and 534.97 kg, respectively. Atmospheric heavy metal dry deposition over the entire year presented a strong ecological risk, with Cd contributing most to this risk. Risk assessment of HM speciation showed that the greatest risks of migration and transformation were for Cd and Pb. The APCS-MLR receptor model identified five and three sources of dry and wet deposition, respectively, in order of proportion of total contribution of: natural wind and sand > road traffic and coal combustion > mineral mining > other human activities > industrial soot.

Atmospheric organic nitrogen deposition around the Danjiangkou Reservoir: Fluxes, characteristics and evidence of agricultural source

Dissolved organic nitrogen (DON) deposition was the substantial component of dissolved total nitrogen (DTN) deposition in the world's nitrogen deposition hot spots areas. However, the information on the importance for DON deposition and its sources was still scarce, which limited the comprehensive assessment of the ecological threat from nitrogen deposition. Six sampling sites around the Danjiangkou Reservoir were set up to collect the dry and wet deposition samples from October 2017 to September 2021. The results showed that dry and wet DTN deposition averaged 34.72 kg ha−1 yr−1 and 22.27 kg ha−1 yr−1, respectively. Dry NH4+-N, NO3−-N and DON deposition averaged 14.28 kg ha−1 yr−1, 5.91 kg ha−1 yr−1 and 14.53 kg ha−1 yr−1, respectively. Wet NH4+-N, NO3−-N and DON deposition averaged 11.14 kg ha−1 yr−1, 3.89 kg ha−1 yr−1and 7.24 kg ha−1 yr−1, respectively. The contributions of DON to DTN were 41.85% (in dry deposition) and 32.50% (in wet deposition), respectively. Dry DON deposition varied between 26.44 kg ha−1 yr−1 and 9.11 kg ha−1 yr−1, and significantly differed among six sampling sites (P < 0.05). The different intensity of agricultural activities disturbance at the sampling sites was the important reason for the spatial variations of DON deposition. DON deposition was significantly correlated with ammonium nitrogen (NH4+-N) deposition (P < 0.05). According to the results of positive matrix factorization (PMF) model, agriculture source contributed significantly to the DON deposition, the contributions at six sampling sites ranged from 45.8% to 73.7% in dry deposition, and from 56.8% to 81.6% in wet deposition. In summary, our findings found that agricultural activities were the important factors influencing the spatial patterns of DON deposition around Danjiangkou Reservoir and provided new evidence for the anthropogenic source of DON deposition in China.

Dry and Wet Deposition Fluxes and Source of Atmospheric Mercury in the Forest in Southeast China

Studying atmospheric mercury (Hg) deposition in a forest system is a key step to understanding Hg biogeochemical cycles. However, observations based on Hg deposition fluxes in worldwide stations under forest ecosystems tend to differ considerably. In this work, a sampling station was set up in Dinghu Mountain to study the atmospheric Hg’s dry and wet deposition in typical forest ecosystems in Southeast China. One hundred and two atmospheric dry and wet deposition samples were collected with an automatic sampler from March 2009 to February 2010, and concentrations of Hg, magnesium (Mg), calcium (Ca), cadmium (Cd), copper (Cu), zinc (Zn), lead (Pb), and chromium (Cr) were detected. The results showed that the annual rainfall weighted average Hg concentration was 56.8 ng L−1, and 79.8 ng L−1 in the dry deposition. The mean total deposition flux was 158.8 μg m−2, and the wet deposition was predominant. The highest and lowest concentrations were detected in the high-temperature rainy season. Generally, the wet deposition flux was notably positively correlated with the rainfall. The source of atmospheric Hg deposition in Dinghu Mountain was analyzed using principal component analysis (PCA). The main source of Hg in precipitation was soil dust, followed by coal and fuel (automobile exhaust). The primary source of Hg in dry deposition was fuel (automobile exhaust), followed by soil dust, which indicates that Dinghu Mountain has been polluted by the anthropogenic sources of Hg.

Distribution and source assignments of polycyclic aromatic and aliphatic hydrocarbons in sediments and biota of the Lafayette River, VA.

The Lafayette River comprises a tidal sub-estuary constrained by an urban watershed that is bounded by residential areas at its upper reaches and port activity at its mouth. We determined the concentrations and distributions of polycyclic aromatic hydrocarbons (PAHs) and aliphatic n-alkanes across 19 sites from headwaters to river mouth in surface sediments (0-2cm). Potential atmospheric sources were investigated through the analysis of wet and dry deposition samples and intact coals from a major export terminal nearby. The potential consequences for human consumption were examined through analysis of native oyster (Crassostrea virginica) and blue crab tissues (Callinectes sapidus). A suite of up to 66 parent and alkyl-substituted PAHs were detected in Lafayette sediments with total concentrations ranging from 0.75 to 39.00µgg-1 dry wt. Concentrations of aliphatic n-alkanes (n-C16 - n-C31) ranged from 4.94 to 40.83μgg-1 dry wt. Source assignment using diagnostic ratios and multivariate source analysis suggests multiple sources contribute to the hydrocarbon signature in this metropolitan system with automotive and atmospheric transport of coal dust as the major contributors. Oyster tissues showed similar trends as PAHs observed in sediments indicating similar sources to water column particles which ultimately accumulate in sediments with crabs showing altered distributions as a consequence of metabolism.

Influence of Atmospheric Phosphorus and Nitrogen Sedimentation on Water Quality in the Middle Route Project of the South-to-North Water Diversion in Henan Province.

In order to understand the potential effects of atmospheric nitrogen and phosphorus deposition on the water quality of the Middle Route Project of the South-to-North Water Diversion Project, samples of dry and wet deposition of atmospheric nitrogen and phosphorus, meteorological factors, and water quality factors were analyzed out to investigate in the Middle Route Project of the South-to-North Water Diversion in Henan Province from October 2018 to October 2020. The variation characteristics of atmospheric nitrogen and phosphorus deposition with time in the Henan section of the main canal are revealed, and the influence of atmospheric dry and wet deposition on the water quality of the middle line is discussed. It was found that the total nitrogen (TN) sedimentation flux has obvious seasonal variation, which was consistent with the variation trend of rainfall, and increased with the increase of rainfall. Nitrogen and phosphorus deposition was significantly correlated with water factors. The effects of meteorological factors and nitrogen and phosphorus deposition on water quality variation reached 18%. The contribution rate and ecological impact of atmospheric nitrogen and phosphorus deposition on water pollution of main channels will be increasing, which needs to be paid enough attention to.

Evaluation of the Terrestrial 222Rn Flux from 210Pb Deposition Measurements

The study of the 222Rn terrestrial flux (Bq/(m2·s) or Bq/(m2·h)) is a complex issue involving both radiation-protection and environmental aspects. While the radiation-protection aspects are quite obvious—it has been well known for several decades that soil is the major source of indoor radon—environmental issues such as the correlation with conventional pollutants (PM2.5, PM10, NOX, etc.) and the use of radon for the esmation of the natural component of GHG (CO2) emissions are relatively less discussed in spite of their growing relevance. In this work we present a method for the estimation of the average value of 222Rn flux from HPGe γ-spectrometry 210Pb measurements performed on wet and dry deposition samples gathered monthly in the period 2006–2020. The results obtained with this technique give an average radon flux in the period Φ = 57 ± 27 Bq/(m2·h), the value of which is comparable with those coming from other methods and direct radon flux measurements as well. The method can thus be used to obtain a worldwide map of the radon flux.

Atmospheric wet and dry depositions of polycyclic aromatic compounds in a megacity of Southwest China

The dry and wet depositions of polycyclic aromatic hydrocarbons (PAHs) and related derivatives have rarely been characterized separately. Parent, oxygenated and nitrated PAHs (PAHs, OPAHs and NPAHs) have been measured in monthly-averaged wet and dry deposition samples collected from January to December 2019 in urban Chongqing. The annual average concentrations of Ʃ17PAHs, Ʃ9OPAHs and Ʃ9NPAHs in wet deposition samples were 457 ± 375, 1311 ± 1416 and 8.25 ± 10.2 ng/L, respectively, with significant monthly variations introduced by rainfall and air-borne particle deposition. Most PAHs species were associated with the particulate phase in wet deposition, while OPAHs and NPAHs were mainly distributed in the dissolved phase, probably due to the lower octanol-water partitioning coefficient of N/OPAHs than that of PAHs. Annual deposition fluxes of PAHs, OPAHs and NPAHs in dry deposition were 25264, 25310 and 388 ng/m2/yr, respectively, higher than those in wet deposition (9869, 24083 and 207 ng/m2/yr). This indicates that PACs, especially PAHs, were removed from the atmosphere mainly via dry deposition. The contributions of wet deposition to total deposited PACs were larger for months with higher precipitation and for PACs with higher molecular weight. Composition pattern and temporal variation results indicated that wet deposition fluxes were mainly affected by precipitation-related particle deposition and chemical properties (e.g., water solubility), while dry deposition fluxes were affected more by factors such as gas/particle partitioning, particle size distribution and physicochemical properties of PACs. Principle component analysis combined with diagnostic ratios revealed that PACs in atmospheric deposition samples were from vehicle emission (48.6%), coal combustion (13.4%), petrogenic source (5.9%) and secondary formation (32.1%).

Platinum group elements in atmospheric PM10 particles and dry deposition in France.

Platinum group elements (PGEs, i.e. platinum, Pt; palladium, Pd; and rhodium, Rh) catalyse over 90% of carbon monoxide, nitrogen oxides and hydrocarbons from combustion residues into water vapour, carbon dioxide and nitrogen in the vehicle's catalytic converter. But there is a major concern over these metals in the scientific world, since they are emitted by catalytic converters and accumulating in the environment. The distribution of PGEs in PM10 fraction was studied in an open urban site (Nantes, France) and in a tunnel (Paris, France) using low- and high-volume air samplers. PGEs were also investigated in dry deposition particles and deposited dust sampled in the tunnel. Pd occurred at the highest levels in both PM10 and dry deposition samples, followed by Rh and Pt. Maximum concentrations in PM10 fraction were 114 pg m-3 for Pd, 14.3 pg m-3 for Rh and 3.3 pg m-3 for Pt in the urban site (Nantes) and 91 pg m-3 for Pd and 16 pg m-3 for Rh in the tunnel (Paris). The concentrations for dry depositions in the tunnel were 261 μg kg-1 for Pt, 431 μg kg-1 for Pd and 85 μg kg-1 for Rh. The results on PGEs levels in atmospheric particles and dry depositions are the first data of their kind in France and will provide new insights into the contribution of catalytic converters to the environment. We also observed Pd and Rh being 2 times higher PM10 particles compared to dry depositions, leading us to suggest that particles rich in Pd and Rh are smaller than 10 μm. An overall concentration trend of Pd > Rh > Pt was observed in all samples, showing the replacement of Pt by Pd and Rh in newer catalytic converters.

Emission and Mass Load of Artificial Sweeteners from a Pig Farm to Its Surrounding Environment: Contribution of Airborne Pathway and Biomonitoring Potential.

An investigation was conducted by determining artificial sweeteners (ASs) in 80 samples from various environmental matrices, including dry deposition, rainfall, soil, leaf, and bark samples around a pig farm in Tianjin, China. Saccharin, cyclamate, and acesulfame were predominant in dry deposition and rainfall samples. Spatially, the distribution of ASs showed a consistent trend of farm center > downwind sites > upwind sites > reference site. The annual total mass loads of saccharin (70%), cyclamate (25%), and acesulfame (5%) via dry deposition and precipitation within a 5 km radius of the pig farm were estimated at 3.9 and 6.2 kg in the average-case and worst-case scenarios, respectively, accounting for 12-18% of the overall emission, indicating that pig farms are a significant source of ASs to the atmosphere and to the vicinal environment via dry and wet deposition. The distribution trends of ASs in tree bark and leaves were similar and tree bark performed better in passively biomonitoring the AS contamination. Overall, pig farms were predicted to release 65-114, 22-38, 2.0-3.5, and 0.6-1.1 tons by feed application in China, Europe, Latin America, and North America, respectively, to the vicinal environment via dry deposition and precipitation.

Spatio-Temporal Variation of Atmospheric Nutrient Deposition in Different Land Uses/Covers around Lake Kivu

Atmospheric deposition of nutrients, particularly nitrogen and phosphorus has the capacity to significantly affect the productivity and biogeochemistry of aquatic ecosystems. The objective of this study was to assess the impact of land use/cover types on the atmospheric deposition of nutrients around Lake Kivu. Dry and wet atmospheric deposition samples were collected from four different land use/cover types (forest, wetland, agricultural and urbanized area) at four stations (Goma, Lwiro, Bukavu and Iko) around the Lake Kivu basin. The highest annual loading of dry total phosphorus (TP) was recorded at a station located in an urban area at Goma (4.4 ± 3.9 μmol/m2/yr) and the highest dry deposition of total nitrogen (TN) was recorded at Iko (84.5 ± 41.2 μmol/m2/yr). High wet TP and TN were at Bukavu (0.7 ± 1.1 μmol/m2/yr) and Iko (21.7 ± 34.7 μmol/m2/yr) respectively. High dry TP loads were recorded in the forest area of Goma and the highest dry TN at Lwiro. High wet TP loads were record in agriculture at Goma and high values of wet TN in agriculture at Iko. Phosphorus and nitrogen deposition rates around Lake Kivu were similar to those reported for other African lakes. The highest rate of TP was recorded mainly in the forest area for dry deposition while high TN was recorded in all types of land use/cover in the basin. This study found out that forest traps high concentration of nutrient than other land uses/covers.

Annual Fluxes of Heavy Metal Elements in Atmospheric Dry and Wet Depositions in the Pearl River Delta Economic Region, Guangdong Province

There are 158 sampling points to be set up in the Pearl River delta economic region. The collecting period is mostly one year, namely, from July 2007 to July 2008. The eight heavy metal elements of Cr, Ni, Cu, Pb, Zn, As, Hg, and Cd in 474 dry and wet deposition samples were tested in terms of the standard procedures. Their average annual fluxes have no obvious difference between dry deposition and wet deposition. So these elements might be at an equilibrium or quasi-equilibrium state between dry deposition and wet deposition.

Atmospheric fluxes of soluble nutrients and Fe: More than three years of wet and dry deposition measurements at Gran Canaria (Canary Islands)

Dust inputs to the oligotrophic waters of the subtropical North Atlantic are of significant importance to the biogeochemistry of the region. In this work, we present fluxes of particles, soluble elements (H+, major ions, Fe and organic ions) in dry deposition (DD) and wet deposition (WD) samples collected between September 2012 and April 2016. Positive Matrix Factorization Model (PMF) indicated four dominant factors influencing the elemental concentrations: marine, crustal and two anthropogenic. Soluble Fe fluxes appear to be affected predominantly by aerosol particle type, with higher values observed at lower dust loading. Although WD fluxes made up only a small fraction of total particle fluxes (12%), they represented an important input of soluble Fe and other nutrients such as nitrate (more than 50% of total amount deposited). This significant contribution to total deposition fluxes may have important consequences for primary production in the surface ocean. Mineral dust is the primary source of soluble atmospheric P to the north Atlantic, which is a region that is already P stressed. Our data show that DD dominates the total flux of soluble P to this area (∼87% of the total flux) and it may have a bigger impact in the diazotroph communities during the summer months when the water column is more stratified and nutrient inputs from deeper water are restricted.

Chemistry of dry and wet atmospheric deposition over the Balearic Islands, NW Mediterranean: Source apportionment and African dust areas

Wet and dry aerosol deposition samples were collected from September 2010 to August 2012 at a remote background site in the Mallorca Isle (Western Mediterranean). Ions and major and trace elements were determined in soluble and insoluble fractions. Temporal variations of chemical components are discussed and interpreted. The overall pattern associated to long-range-transport air masses is studied: Dry/Wet deposition ratios, charges and composition depend clearly on the meteorological scenario. E.g. Dry/Wet ratio is 1:1 when air comes from North Africa, in contrast to a 1:9 ratio under the mainland Europe influence.Moreover, an innovating source apportionment study was conducted integrating both dry and wet deposition samples. Six sources were revealed, including marine aerosols (32%); two different mineral factors, African dust (15%) and regional dust (12%); two anthropogenic factors, one related to road traffic (8%) and another to regional sources (17%); and a mixed factor having biomass burning emissions and others sources (17%). Temporal variations and influence from long-range-transport air masses are also investigated.Fertilization deposition trends have also been explored, observing nutrients settling, as well as nitrate and sulphate, due to their agricultural interest. An important peak during January–February 2012 is studied in depth.Having in mind the strong impact of African dust on the global deposition budget, the analysis of elemental ratios between key dust components was investigated in order to identify major source areas affecting Western Mediterranean: Western Sahara, Algeria-Hoggar Massif and Tunisia-Libya. Differences among these regions are evident. E.g. the impact of industrial emissions is well-detected under outbreaks from Tunisia-Libya, with relatively high content of Ni and Pb.

Major Ion Composition of Dry Deposition in Kirklareli, Turkey

The chemical composition of dry deposition in Kirklareli (Turkey) is presented in this study. During the sampling period, in a total of 28 dry deposition samples which were collected in two stations which are Central District and Kaynarca Town, the concentrations of major cations (Na+, Mg2+, Ca2+, K+, NH4+) and major anions (Cl-, NO3-, SO42-) were determined and pH values were also measured. In both sampling stations, arithmetic mean concentration values of major cations are Ca2+ > NH4+ > K+ > Na+ > Mg2+ and those of major anions are SO42- > Cl- > NO3- in dry deposition samples. By calculating the enrichment factors (EF) of the chemical components and non-sea salt (NSS) concentration values, it has been aimed to determine the ion sources in the dry deposition. Non-sea salt fraction (NSSF) values of Ca2+ and K+ ions are 99% and 96%, respectively, in both sampling stations. Fluxes of dry deposition of ions were calculated. In both stations, among all ions, sulphate ion is the one which has the highest mean dry deposition flux value.

Measurement of size-fractionated atmospheric particulate matter and associated polycyclic aromatic hydrocarbons in Mumbai, India, and their dry deposition fluxes

Size-fractionated particulate matter (PM), associated polycyclic aromatic hydrocarbons (PAHs), and their dry deposition fluxes were measured in a coastal urban environment of Mumbai, India. PM samples were collected using a variable configuration cascade impactor (VCCI) with 11 size fractionation stages. Dry deposition samples were collected using a round-bottomed PVC tray. High-performance liquid chromatography (HPLC) was used for the identification and quantification of PAHs in samples. PM were observed to range between 58 and 130 μg m−3, with a mean dry deposition flux of 1298 mg m−2 day−1. Observed PM concentrations during the sampling period were found to be well above the WHO Air Quality Guidelines. A strong linear correlation was observed between the gravitational settling velocities and estimated dry deposition velocities for PM. Concentrations of PAHs associated with PM were observed to be in the range 101–145 ng m−3 while their dry deposition fluxes varied from 1008 to 1160 ng m−2 month−1. The molecular diagnostic ratios (MDRs) indicated that sources of PAHs in the study area were petrogenic as well as non-traffic. The dry deposition velocities calculated for PAHs were in the order of 10−4 cm s−1 to 10−3 cm s−1 in the entire size range.

A Christmas gift: Signature of the 24th December 2018 eruption of Mt. Etna on the chemical composition of bulk deposition in eastern Sicily

The eruption of Mt. Etna which occurred on December 24th 2018 was characterized by strombolian activity and fire fountains, emitted by the New South-East Crater and along a fissure that propagated towards the SE. The influence of volcanic emissions on atmospheric deposition was clearly detectable at several kilometres from the source. Wet and dry (bulk) deposition samples were collected each month, through a network of eleven collectors, in the areas of Milazzo, and Priolo between June 2018 and June 2019. They were analysed for major ions and trace elements concentrations. The pH values range from 3.9 to 8.3, while the EC values range from 7 to 396 μS cm-1. An extensive neutralization of the acidity has been recognised mainly due to the suspended alkaline dust particles, which have a buffering role in rainwater. A high load of Na+ and Cl- was observed at all sites, related to the closeness of the study areas to the coast, showing a high positive correlation (R2 = 0.989) along the line of Na+/Cl- ratio in seawater. During the eruption, the volcanic plume was carried by the winds for long distance (more than 300 km) affecting the area of Priolo but not that of Milazzo, which was upwind with respect to Mt. Etna. The impact of volcanic HF was clearly recognised in the samples collected after the eruption. Volcanic SO2 and HCl had a lower impact due to the overwhelming input of anthropogenic sulfate and marine chloride. On the contrary, the signature of the Mt. Etna eruption can be well recognised in the high concentrations of certain trace elements in the samples collected immediately after the eruption. The strongest contrast between affected and non-affected samples was recognised in Al, Cd, and especially in the volatile elements Tl and Te, which are typically enriched in volcanic emissions. The results showed that volcanic eruptions might have a relevant effect on the atmospheric chemistry and on the composition of rainwater up to distances of 80 km from the emission vents.