The key aims of this project were: (i) investigation of atmospheric nitrogen deposition, focused on discrimination between bulk, wet and dry deposition, and between particulate matter and gas phase, (ii) accurate quantification of the contributions of dissolved organic and inorganic nitrogen to each type of deposition, and (iii) exploration of the origin and potential sources of atmospheric water soluble organic nitrogen (WSON). This project was particularly focused on the WSON fraction because, despite it being a potentially important source of bioavailable reactive nitrogen, a number of questions regarding its deposition mechanism (wet vs. dry), composition and origin (natural, anthropogenic or mixed) remain unanswered. There are two major difficulties in WSON determination: (i) the diversity of organic nitrogen compounds compared with the inorganic forms, and (ii) the lack of a direct determination method: the derivation of organic nitrogen concentrations in an aqueous sample involves the determination of the dissolved inorganic nitrogen (DIN) species concentration, comprising nitrate and ammonium, the determination of the total dissolved nitrogen (TDN) concentration, and the subtraction of the DIN concentrations from the TDN concentration. TDN determination requires a preparatory digestion step: high-temperature catalytic oxidation was the method used in this study. Ion chromatography (IC) was the method of choice for nitrate determination, whilst ammonium determination was by IC for rain samples, and by flow injection analysis for air samples collected into aqueous media. This thesis is structured in 3 main parts: the first part 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 were the standard rain gauges used in the UK national network for monitoring precipitation composition. “Dry+wet” deposition collectors were flushing rain gauges equipped with a rain detector, a spray nozzle, a 2-way valve and two independent bottles to collect funnel washings (dry deposition) and true wet deposition. A key objective in this part of the work was the accurate quantification of inorganic and organic water-soluble nitrogen species contribution to each type of deposition. On average, for the 27 weekly samples with 3 valid replicates for the 2 types of collectors, DON represented 23% of the 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 and flushing rain gauges, for deposition of both TDN and DON, suggesting biological conversion and loss of inorganic N in the flushing samplers. The second stage of this project was the investigation of in situ atmospheric concentrations of WSN species, both organic and inorganic. Simultaneous daily measurements of ammonium, nitrate and WSON were made between July and November 2008 at the same semi-rural site in south-east Scotland. Discrimination between material from the gas and particle phases was achieved by means of Cofer scrubbers and PTFE membrane filters, respectively. Average concentrations of NH3 (determined as NH4+), NO2/HNO3 (determined as NO3-) and WSON in the gas phase were 82 ± 54 nmol N m-3, 2.6 ± 2.5 nmol N m-3 and 18 ± 12 nmol N m-3 respectively, and in the particle phase were 20 ± 24 nmol N m-3, 10 ± 9 nmol N m-3 and 8 ± 7 nmol N m-3 respectively (± represent standard deviation across all valid daily samples, not error of triplicate samples). Except for oxidised inorganic N, average concentrations in the gas phase were larger than in the particle phase. No evidence of solely agricultural or solely combustion sources of WSON was found, as no correlation in either phase between WSON and either NH4+ or NO3- could be established. The final stage of this project was to gain a broader picture of nitrogen deposition across Europe. Rain samples were analysed for TDN and DIN from a network of 21 different sampling locations, from the south of Portugal to the north of Finland. The average DON contribution across the 21 sampling sites was ~ 19% and, according to the data gathered in this study, DON species appeared largely unrelated specifically to agricultural or to combustion nitrogen sources, although the results varied widely from site to site. Overall, this work has shown that ON and its deposition comprises a significant component of total atmospheric reactive nitrogen.

Polycyclic aromatic hydrocarbons (PAHs) are one of major classes of organic pollutants. As semi-volatile organic compounds, PAHs can be transported in the atmosphere and scavenged according to various processes (dry and wet deposition). Atmospheric deposition is an important pathway for the transfer of pollutants from atmosphere to the terrestrial and water surfaces. The objective of this research is to quantify the dry and wet deposition of the atmospheric PAHs in the Kaohsiung coastal area. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) were also performed with diagnostic ratios to determine the potential sources of PAHs. The mean dry and wet deposition fluxes of atmospheric total suspended particles (TSP) during the study period (January-December 2010) were estimated to be 44.3 (6.60-384) and 211 (56.1-738) mg/m2d, respectively. The annual mean total PAH fluxes in dry and wet deposition were 1500 (749-3760) and 8470 (2280-46000) ng/m2d, respectively. Both concentrations and dry deposition fluxes of TSP were much higher during dust storm. During Ghost Month, however, they were comparable with other sampling events. By comparing with literatures, the total PAH concentrations of TSP were relatively low during Ghost Month, suggesting that wind direction and precipitation might be plausible. The ratio of PM2.5/PM10 had a relatively low value during dust storm, indicating that coarse particle might be predominant. In addition, during dust storm, both TSP dry deposition velocity and total PAH dry deposition velocity were higher than other sampling events. Our findings in this study showed that previous attempts in literature to estimate total PAH dry deposition fluxes by using TSP dry deposition velocity and PAH concentrations could lead to overestimate fluxes in the field. TSP dry deposition fluxes were positively correlated with atmospheric total TSP concentrations and TSP dry deposition velocity, but were correlated negatively with intensity of precipitation. In addition, TSP dry deposition velocity showed a positive correlation with TSP concentrations. Total PAH dry deposition fluxes were correlated positively with atmospheric total particulate concentrations and total PAH dry deposition velocity, but negatively with intensity of precipitation and temperature. However, TSP and total PAH fluxes in wet deposition were both correlated positively with intensity of precipitation. Diagnostic ratios showed that diesel exhaust was the main source of combustion-derived PAHs in the study. HCA and PCA analysis indicated that emissions from the ships and vehicles, and fuel used were the main sources of combustion-derived PAHs, while during special events, such as dust storm and Ghost Month, suggesting a different source of PAHs.

No description available.

No description available.

Methylmercury (MeHg) is a potent vertebrate neurotoxin and a contaminant of global concern. Increased anthropogenic emissions of mercury (Hg) to the atmosphere have led to increased bioaccumulation of MeHg in top predatory organisms such as fish, the consumption of which is the main exposure pathway of this toxin to humans and other animals. Forest canopies significantly increase the deposition of Hg in general to watersheds, but sources and fates of MeHg deposition in particular remain poorly understood. In this study, wet and dry loadings of MeHg to a watershed were quantified, and the retention and (photo)reduction of MeHg on foliage were measured using unique stable isotope experiments. We found that traditional methods of quantifying net deposition underestimate incoming sources of MeHg, and that retention of MeHg on forest canopies results in delayed transport of a significant portion of newly deposited MeHg from terrestrial catchments into adjacent lakes. / Ecology

Os processos de remoção de espécies químicas da atmosfera têm sido estudados atualmente utilizando modelos numéricos, na tentativa de compreender melhor, os processos de transferências de gases e material particulado (sejam elas naturais ou antropogênicas) intra-reservatórios na atmosfera e seus efeitos na dinâmica do tempo e clima. Neste estudo, foi utilizado o modelo RAMS para simular a estrutura vertical das nuvens que se desenvolvem na região amazônica, em conjunto ao modelo de remoção B. V. 2, para os processos de remoção úmida que ocorrem tanto dentro quanto abaixo da nuvem, além das condições atmosféricas locais da região da Bacia Amazônica para, assim, simular a transferência das espécies químicas da atmosfera para a hidrosfera dentro do escopo do projeto LBA. Dentro deste projeto, foram realizadas campanhas intensivas de medições, como a LBA/DRY-TO-WET e LBA/SMOCC (setembro a novembro de 2002) na região de Rondônia. No período das campanhas, foram realizadas medições das concentrações dos gases amônia, ácido nítrico e dióxido de enxofre, além das espécies inorgânicas solúveis em água, como amônio, nitrato e sulfato, entre outros. Estas concentrações de gases e partículas, bem como os parâmetros meteorológicos obtidos durante as campanhas, realizadas durante o período de transição entre as estações seca e chuvosa na região, foram utilizados como dados de entrada para ambos os modelos, onde foram escolhidos alguns eventos específicos. Com intuito de melhor representar o espectro de gotículas de nuvens no modelo de remoção, foram utilizadas a função de distribuição de Levine & Schwartz, 1982 e funções gama ajustadas aos dados observados em distribuição de gotículas de nuvem obtidas em vôos efetuados durante o experimento. Conseqüentemente, este trabalho visou à simulação da concentração na água de chuva de três espécies químicas (SO42-, NO3- e NH4+) removidas da atmosfera pelo evento de precipitação, comparando-as às composições químicas da água de chuva observadas experimentalmente, em dois eventos selecionados (9 e 10 de outubro de 2002). Simulações atmosféricas com o RAMS apresentaram resultados bastante satisfatórios conseguindo representar aspectos microfísicos das nuvens que se desenvolvem na região amazônica com bastante fidelidade. Os resultados da modelagem dos processos de remoção mostraram uma boa concordância com os observados, principalmente para o sulfato (que em alguns casos a quantidade encontrada na água de chuva pela simulação foi 97% da observada) em ambos os eventos, quando a altura da nuvem foi considerada mais realista para região (16 km). Além disso, observou-se que o espectro de gotículas de nuvem utilizado foi um parâmetro importante nos resultados. Os resultados mostraram ainda, uma predominância dos processos que ocorrem dentro da nuvem, sendo estes responsáveis por cerca de 80% a 97% da concentração da espécie química encontrada na água de chuva, corroborando a literatura. Com isso, ficou evidente a complexidade das interações e transferências entre os reservatórios atmosfera / hidrosfera através dos processos de remoção de poluentes, ressaltando assim, a importância dos estudos sobre este assunto. / The scavenging processes of chemical species have been studied using numerical modeling in order to understand the gases and particulate matter intra-reservoir transferences (natural or anthropogenic) which affect weather and climate. In this study RAMS model was used in turn to simulate cloud vertical structure formed over Amazonian area working together to B.V.2 scavenging model. The last model was used to simulate the in- and below-cloud scavenging processes, besides the local atmospheric conditions within the LBA Project. In this Project, there were evaluated many measurements of LBA/DRY-TO-WET and LBA/SMOCC (September to November) Campaigns at Rondonia State. During the Campaigns, ammonia, nitric acid and sulfur dioxide gases were evaluated and their respective particulate matter, ammonium, nitrate and sulfate, among others, as well as rainwater chemistry. These concentrations and meteorological parameters were also obtained, during the transition from dry to wet season, and used as input data to the both modeling, where some events were chosen. With the intention of modeling improvement, cloud droplet spectra were used from Levine & Schwartz, 1982 and gamma functions, according to each case and based on the droplet distribution obtained from flight collected data during the field Campaign. Consequently, this work simulated the rainwater concentrations of three chemical species (SO42-, NO3- e NH4+) scavenged from atmosphere by the precipitation event and compared to the observed data of two selected events (9 and 10 October 2002). RAMS atmospheric simulations presented satisfactory results which showed detailed cloud microphysics processes of Amazonian region. The modeling results show good agreement of observed data, mainly to sulfate, reaching 97% of the observed sulfate for both events, when the cloud height was considered more realistic for the region (16 km). Besides, the cloud droplet spectra were an important parameter to the modeling. The results also showed that the in-cloud process is responsible by 80% to 97% of the chemical species found in rainwater. Additionally, it was clear that the complexity of the interaction and intra-reservoir transferences through the scavenging processes and their importance.

Per- and polyfluoroalkyl substances (PFAS) are a group of highly fluorinated compounds which comprises of more than 4700 substances. A smaller number of those substances is rou-tinely measured, usually the short (C4-C7) and long chain PFAS (>C7). Detection of PFAS in different water matrices including wet precipitation have been done previously in a limited number of studies, including ultra-short chain compounds (C1-C3). Ultra-short chain com-pounds have however not been investigated to a larger extent. In this study, twelve rainwater samples from Råö have been analysed, each representing a composite sample of one month. Long (C8-C18), short as well as ultra-short chain PFAS have been included in the analysis. Long and short chain compounds were analysed with ultra-performance liquid chromatography tan-dem mass spectrometer (UPLC-MS/MS) and ultra-short chain compounds with ultra-perfor-mance convergence chromatography tandem spectrometer (UPCC-MS/MS). Long and short-chain PFAS had a total detectable concentration of 5.1-110 ng/L. A seasonal trend was also studied, which showed a significant difference when performing a Kruskal Wallis test in meas-ured total mean long and short chain PFAS concentration. Dunnet´s test indicated a significant difference between all the seasons. Highest concentrations were measured during summer and lowest during winter. Ultra-short chain compounds analysed by UPCC MS/MS had a total concentration between 16-410 ng/L. No significant difference in total ultra-short PFAS mean concentration could be seen between different seasons using a Kruskal Wallis test. The total PFAS concentration in the rain samples ranged from 28 to 540 ng/L, where ultra-short chain PFAS contributed to 58-92 % of the total concentration. Which makes them an important group to include in future measurements of PFAS in water samples and especially in rainwater sam-ples.

The characteristics of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and the variation of the gas-particle partitioning of PCDD/Fs near two municipal solid waste incinerators (MSWIs) located in southern Taiwan were investigated. In order to better understand the mechanism of dry deposition, the atmospheric dry deposition flux and velocity of PCDD/Fs were calculated. It was found that the mean atmospheric PCDD/F concentrations (0.0348-0.106 pg I-TEQ/Nm3) were comparable to those detected in the vicinity of MSWIs in Taiwan, but significantly lower than those in a highly industrialized urban area (0.150 pg I-TEQ/Nm3) located in southern Taiwan. The relatively higher atmospheric PCDD/F concentrations was found in winter than in summer. The calculated total dry deposition flux of PCDD/Fs ranged from 0.0274-0.718 ng I-TEQ/m2-month, and the atmospheric deposition flux in winter tended to be higher than those in summer. The results also indicated that dry deposition velocities of atmospheric particles for each month ranged from 0.52-0.91 cm/s (mean = 0.63 cm/s) and 0.48-0.73 cm/s (mean = 0.55 cm/s) in sites A and B, respectively, which were similar to that for the ambient air near two MSWIs in Taiwan, but slightly higher than those in urban area of Korea. In addition, the dry deposition of PCDD/Fs was mainly contributed by particle-phase at both sampling areas during the estimated period. The above results demonstrated that the dominant mechanism of dry deposition was particle phase deposition. The annual variations of wet deposition of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in atmosphere were also measured at two sites (A and B). Results showed that particle scavenging dominates in the wet deposition processes for the removal of PCDD/Fs from the atmosphere, the highest value was observed at the highest chlorinated congener. The ambient temperature and the amount of precipitation played an important role in the variation of PCDD/F deposition fluxes. It was found that temperature was inversely associated with the existence of particulate PCDD/Fs, indicating PCDD/Fs are scavenged most efficiently in cold weather. PCDD/F wet deposition fluxes in rainy seasons (from June to August) were significantly higher than those in dry seasons (from December to February), revealing a positive relationship between wet deposition flux and monthly rainfall. Additionally, the annual total (dry + wet) deposition fluxes of PCDD/Fs were 149 ng/m2-year (5.02 ng I-TEQ/m2-year) and 177 ng/m2-year (5.11 ng I-TEQ/m2-year) for sites A and B, respectively, revealing that dry deposition was more dominant than the wet deposition for the atmospheric deposition of PCDD/Fs. Since atmospheric deposition is believed to be the main transfer pathway of PCDD/Fs into food chains, its impact on human exposure to PCDD/Fs is of great importance.

No description available.

In this work, wet deposition samples were collected at Middle East Technical University campus, Ankara, between December 2000 and May 2002. Snow samples were collected from 50 grids in January, 2001 in Ankara to investigate dry deposition of PAHs. The collected samples were preconcentrated by Solid Phase Extraction and ultrasonic extraction tecniques. Extraction methodologies were improved prior to analysis of samples. Extracted samples were analyzed by Gas Chromotography-Mass Spectrometry for 14 Polycyclic Aromatic Hydrocarbons. Selected Ion Monitoring mode was used throughout the analysis. Phenanthrene, fluoranthene, pyrene and benzo (b+k) fluoranthene were found to be dominant PAHs in wet deposition samples. Seasonal variation of PAHs were observed having higher concentrations in winter period. Meterological parameters were also examined together with PAH concentrations. Contribution of PAHs coming from North East and South West direction were found to be dominant. Wet deposition fluxes were calculated and compared with other urban sites. Wet deposition fluxes are lower than industrial sites and comparable with urban sites in Europe. PAH ratios and factor analysis results demostrated combustion and traffic emissions are major sources of pollutants in the city. Dry deposition of PAHs were invesigated using snow as a natural collecting surface. Dry deposition fluxes calculated using snow surface are compareble with other similar sites. Dry deposition pollution maps of PAHs were drawn by MapInfo software and it was observed that the major pollution regions are the localities where low income families live and low quality coal used for heating purpose. Ratio calculations showed that the central parts of the city is mostly affected from traffic emissions while coal emissions are dominating at the other parts of the city. Factor analysis applied to data set and 6 factors distinquished as coal, soil, traffic, oil combustion, mixed combustion and road dust.