With a burgeoning population, increasing land area, and the emergence of new megacities, urban areas have the ability to alter biogeochemical cycles across great scales. Though cities are hotspots of pollution, these concentrated population centers present an opportunity to reduce the human footprint and provide a model of sustainability. Creating sustainable cities requires an understanding of urban biogeochemical cycles of nutrients, such as carbon (C), nitrogen (N), and phosphorus (P). Studies in urban areas, however, often include measurements at only a few sites, either in an urban-rural comparison or as an anchor along an urban-rural gradient. In my dissertation work, I deployed a network of sites across the greater Boston area to measure several key biogeochemical processes: 1) rates of carbon dioxide (CO2) efflux through soil respiration, 2) atmospheric inputs and soil solution concentrations of N, P, and organic C, and 3) rates of N mineralization and nitrification in soils. I found that urban soil respiration is driven by landowner management and that respiration from urban residential soils produces almost 75% of the CO2 as fossil fuel emissions in these areas during the growing season. I also found that mean fluxes of inorganic N in throughfall are double rural rates and vary more than threefold throughout the urban area, exhibiting rates at some urban sites which are as low as rural rates. These rates are driven by vehicular N emissions and local fertilizer inputs, and are decoupled from rates of soil biogeochemical cycling of C and N. Finally, I found atmospheric fluxes of organic N equaling almost 40% of total atmospheric N inputs, atmospheric inputs of organic C on par with rural rates, atmospheric inputs of P similar to rates of P in parking lot runoff, and an enhancement of nutrient inputs to urban ecosystems by the urban tree canopy. My dissertation work highlights the need for a more thorough understanding of biogeochemical fluxes in cities, provides further impetus for the development of a more holistic, multifaceted understanding of urbanization, and suggests that urban areas should be studied as systems unto themselves, rather than strictly in comparison to rural areas.

Devido a sua grande amplitude altitudinal, o Parque Estadual da Serra do Mar - PESM - abriga fisionomias variadas da Floresta Ombrófila Densa, essas fisionomias se distribuem ao longo das cotas de níveis de maneira padronizada. Este trabalho busca avaliar a contribuição da deposição úmida, através de chuva, na distribuição dessas fisionomias. Para viabilizar o estudo nas diferentes altitudes foram escolhidos dois dos núcleos administrativos do PESM: o núcleo Picinguaba, o único entre eles a atingir o nível do mar, e o núcleo Santa Virgínia, que contempla as cotas mais altas de altitude e, conseqüentemente, as formações florestais a elas relacionadas. Observou-se em Picinguaba uma maior taxa de deposição de nitrogênio e carbono. A condutividade elétrica da água da chuva também foi maior em Picinguaba, evidenciando que outros elementos, como cloro, sódio, magnésio, entre outros, também são depositados em maiores taxas em Picinguaba. Assim, a variação nas fisionomias florestais ao longo do gradiente de altitude da serra do mar pode estar, em parte, associada às diferentes taxas de deposição atmosférica / Due its altitudinal amplitude, the Serra do Mar State Park (PESM), shelters a variety of physiognomies of the Dense Ombrophylous Forest, such physiognomies are distributed along the level quota in a standard way. This work aims to evaluate the contribution of the moist deposition through the rain, in the distribution of these physiognomies. In order do make the study in different altitudes possible, two PESM administrative nucleus were chosen: the Picinguaba nucleus, the only one among these ones that reaches the sea level, and the Santa Virginia nucleus which contemplates the highest quotas of altitude and consequentially, the forest formations related to them. It was observed in Picinguaba a lower rate of nitrogen and carbon deposition. The electrical conductivity of the rain water was higher in Picinguaba, putting into evidence that other elements, such as chlorine, sodium, magnesium, and others are also deposited in higher rates in Picinguaba. Thus, the variation in the forest physiognomies along the altitudinal gradient of Serra do Mar could be, in part, related to the different rates of the atmospheric deposition

Les tourbières sont communément utilisées comme archives de dépôts de mercure (Hg). De nombreuses études ces dernières décennies ont montré que les taux d’accumulation de Hg (HgARs) ont augmenté en réponse à l’industrialisation. Les signatures isotopiques en Hg se révèlent très utiles pour mieux caractériser les dépôts de Hg. Elles ont permis de montrer que les dépôts secs de Hg élémentaire gazeux (GEM) dominent les dépôts de Hg sur la tourbière du Pinet. L’analyse d’échantillons de tourbe provenant de plusieurs tourbières en hémisphère nord montre que les dépôts secs de GEM dominent globalement les dépôts de Hg. Les tourbières pourraient donc être utilisées comme archives à la fois des dépôts humides et des concentrations en GEM pendant l’Holocène. On présente la première reconstruction quantitative des concentrations passées en GEM à partir de carottes de tourbe. L’impact de l’Homme sur le cycle du Hg a eu pour conséquence une augmentation graduelle des concentrations en GEM de 0,2 (10 000 – 4000 BP) à 3,5 ng m-3 (20ème siècle), accompagnée par des modifications de signatures isotopiques du Hg atmosphérique. Cette première utilisation de tourbières comme archives de concentration et d’isotopie du GEM est prometteuse, et devrait être étendue à la période pré-anthropique pour étudier les variations naturelles du cycle du Hg pendant l’Holocène. / During the past few decades, peatlands were successfully used to investigate historical mercury (Hg) deposition. The chronology of Hg accumulation rates (HgARs) to peatlands is well constrained, with recent increases in HgAR associated with anthropogenic Hg emissions and deposition. The use of Hg stable isotopes in peatland ecosystems provides new opportunities to better characterize and understand historical Hg deposition. In an extensive study conducted at the Pinet peat bog (French Pyrenees) we identify gaseous elemental Hg (GEM) dry deposition, via foliar uptake, as the dominant Hg transfer pathway from the atmosphere to peat vegetation. Based on the Hg isotope analysis of multiple northern hemispheric peat records, we find that GEM dry deposition dominates Hg deposition globally. We suggest that peatlands can be used as archives of both past Hg wet deposition, Hg dry deposition and GEM concentration. We present the first quantitative reconstruction of historical atmospheric GEM concentrations using peat archives from the Pyrenees. The Human impact on Hg cycling caused a gradual increase in GEM concentrations from 0.2 (10,000 – 4000 BP) to 3.5 ng m-3 (20th Century) and was accompanied by a change in atmospheric Hg isotope signatures. This first comprehensive study on Hg isotope deposition to peatlands is promising and should be extended to pre-anthropogenic times to investigate natural variations in atmospheric Hg dynamics during the Holocene.

Thesis (M. Sc.(Chemistry)) -- University of Limpopo, 2017. / Great Letaba and Mokolo Rivers are major sources of water for domestic use, agriculture and recreational activities in Limpopo Province, South Africa. These Rivers are predisposed to pollution sources from atmospheric deposition of mine dust, emissions from power stations and burning fuel, return flows from agriculture and municipal wastewater discharges and sewage effluents, which may potentially affect the quality of water and the inhabiting biota. Arsenic (As) is an element of prime concern in aquatic systems exposed to such pollution sources due to its toxicity to humans and aquatic life. The quantification and speciation of As in Mokolo and Great Letaba Rivers is important to assess the current levels and predict future trends in the quality of the two rivers. Speciation of As in water and sediments is crucial since the toxicity depends on its chemical forms. In this study, various analytical approaches were explored to precisely identify and quantify different As species in water and sediment samples collected from Great Letaba and Mokolo Rivers. Sample preparation was carried out with an intensive care to efficiently identify and quantify As species. Identification of each species in the samples was based on matching standard peaks with retention times by simple injection of standards of As species into Hamilton PRP X100 column. The chromatographic separation and determination of As3+, dimethylarsinic acid (DMA), monomethylarsonic acid (MMA) and As5+ in water and sediment samples were achieved by on-line coupling of high performance liquid chromatography (HPLC) to inductively coupled plasma-mass spectrometry (ICP-MS). A novel extraction method for As species in sediments based on 0.3 M (NH4)2HPO4 and 50 mM EDTA showed no species interconversion during extraction. Baseline separation of four As species was achieved in 12 minutes using gradient elution with 10 mM and 60 mM of NH4NO3 at pH 8.7 as mobile phases. The analytical figures of merits and validation of analytical procedures were assessed and adequate performance and percentage recoveries ranging from 81.1 – 102% for water sample and 73.0 – 92.0% for sediments were achieved. The As species concentration in water and sediment samples were found in the range 0.224 – 7.70 μg/L and 74.0 – 92.0 ng/g, respectively. The DMA was not detected in both water and sediment samples. viii The As content in sediments depends on the solid phase partitioning between inorganic As species and trace elements such as iron (Fe), manganese (Mn) and aluminium (Al). Knowledge of the extent of this partitioning is important to evaluate the distribution and pathways of As in water, aquatic organisms and possible exposure of animals and human beings. Therefore, total concentrations of As, Fe, Mn and Al in water and sediment samples were determined using ICP-MS and inductively coupled plasma–optical emission spectrometry (ICP-OES). The analytical procedures were validated using standard reference materials (SRMs) with percentage recoveries of trace elements ranging 84.0 – 95.6% for water samples and 75.0 – 120% for sediments. The As, Fe, Mn and Al concentrations obtained were further assessed for safe drinking water, irrigation water and for sediments quality about standard guidelines. Moreover, As species concentrations correlated with Fe, Mn and Al and the observed interactions depend on the adsorption capacities between As species and these trace elements. The inorganic species in water samples were also determined by employing off-line mode of solid phase extraction (SPE) procedure using multi-walled carbon nanotubes (MWCNTs) impregnated branched polyethyleneimine (BPEI) as an adsorbent material. The MWCNTs-BPEI characterised with X-ray powder diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and Thermogravimetric analysis (TGA) techniques indicated successful modification of the nanomaterial. The MWCNTs-BPEI exhibited selective retention of As5+ in the presence of As3+ in water samples with the achieved pre-concentration factor of 23.3. The retained As5+ was then eluted and detected using ICP-MS. A limit of detection (LOD) of 0.0537 μg/L and limit of quantification (LOQ) of 0.179 μg/L were achieved. The obtained percentage recovery of 81.0% validated the SPE procedure for selective retention of As5+. The As5+ concentrations determined after the SPE procedure were found in the range of 0.204 – 7.52 μg/L, which are in good agreement with As5+ results obtained using HPLC-ICP-MS.

Orientador: João Andrade de Carvalho Junior / Resumo: O nitrogênio (N) é um elemento fundamental para os seres vivos; contudo, o N disponível biologicamente é aquele conhecido como nitrogênio reativo (Nr). O presente trabalho propõe quantificar e analisar a variabilidade espacial da concentração e deposição atmosférica seca de nitrogênio reativo no estado de São Paulo, através de sua fase gasosa (HNO3; NH3; NO2) e particulada (NO3-; NH4+). Amostradores de coleta por Denuder (DELTA) foram distribuídos espacialmente em seis sítios de amostragem, abrangendo diferentes tipos de cobertura do solo e urbanização. As amostras foram coletadas ao longo de dois anos (2015-2017). A forma dominante de Nr inorgânico na atmosfera foi o NO2 gasoso em todos os locais de amostragem, o que representou 79% do total. As concentrações médias de NH3, HNO3, NH4+ e NO3− foram de 10%, 3%, 6% e 2% do total de Nr, respectivamente. A umidade relativa e a velocidade do vento foram significativas para explicar parte da variabilidade das concentrações de Nr na atmosfera, enquanto a precipitação foi importante apenas para a concentração de NO2. A deposição média de Nr seco no Estado de São Paulo foi de 8,9 kgN ha-1 ano-1. A maior deposição média de Nr foi encontrada no sudeste do Estado de São Paulo e está relacionada ao intenso tráfego de veículos, gerenciamento de resíduos e atividades industriais. Considerando a região onde a Mata Atlântica está localizada, este trabalho mostra que a deposição total de Nr seco por si só (sem considerar a deposição de espécie... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Nitrogen (N) is a fundamental element for living beings; however, the biologically available N is known as reactive nitrogen (Nr). The current work proposes to quantify and analyze the spatial variability of the concentration and dry atmospheric deposition of reactive nitrogen in the state of São Paulo, through its gas phase (HNO3; NH3; NO2) and particulate phase (NO3-; NH4+). Denuder collection samplers (DELTA) were spatially distributed in six sampling sites, covering different types of ground cover and urbanization. The samples were collected over two years (2015-2017). The dominant form of inorganic Nr in the atmosphere was gaseous NO2 in all sampling sites, what represented 79% of the total. The average concentrations of NH3, HNO3, NH4+ and NO3- were 10%, 3%, 6%, and 2% of the total Nr, respectively. The relative humidity and wind speed were significant to explain part of the variability of Nr concentrations in the atmosphere, while precipitation was important only for the concentration of NO2. The average of dry Nr deposition in the State of São Paulo was 8.9 kgN ha-1 year-1. The highest average deposition of Nr was found in the southeastern of São Paulo state and is related to the intense vehicle traffic, waste management, and industrial activities. Considering the region where the Atlantic Forest is located, this work shows that the total deposition of dry Nr by itself (without considering the deposition of wet or organic species) exceeded the critical load of Nr sugg... (Complete abstract click electronic access below) / Mestre

The objective of the Master thesis is to estimate the fog contribution on atmospheric deposition with the usage of stable isotopes. The crucial part of the thesis was to perform (first of its kind in the Czech Republic) the relative isotope composition 18 O a 2 H of fog. In the same time, the composition of rain and throughfall was performed. The collection of each type of precipitation took place in five sampling points of Academy of Science within three mountain regions including Krkonoše, Šumava and Jizerské Hory during October and November 2017. The sampling took 14 days in total and it was performed by using TC/EA ThermoBremen and mass spectrometer Delta ThermoBremen at South Bohemian University in České Budějovice. The results confirmed that fog is isotopically heavier in comparison to regular rain. As for the relative isotope composition 18 O and 2 H of each areas, no significant difference was observed. Results of the fog participation on atmospheric deposition in Krkonoše and Šumava can be seen after drafting a simple linear mixing model. The fog contribution on atmospheric deposition in Šumava for 18 O is 4,7 % and for 2 H is 6,4 18 O. For one area in Krkonoše, the average participation for 18 O is 3,6 %. Key words: stable isotopes, oxygen, hydrogen, fog

Atmospheric deposition has been suggested to be a major input pathway of perfluoroalkyl acids (PFAAs) to the Baltic Sea catchment area and to the Baltic Sea itself. However, the sources of PFAAs to the atmosphere are not well characterized. In this study we investigated if waste incineration plants in Sweden could be a source of PFAAs to the atmosphere and to the environment in general. Samples of the end products from waste incineration were collected at four different incineration plants. The plants differed in size and technical advancement and were considered to be representative for the majority of waste incineration plants in Sweden. The collected samples were slag from the furnaces, fly ash from the flue gases, “bambergkaka” (a mix of fly ash and sludge from wastewater treatment) as well as condensate and wastewater from the cleaning process of the flue gases. Two methods were developed, one for analysis of PFAAs in solid samples and one for water samples. Method validation showed good performance for both methods in terms of precision and accuracy, despite low recoveries obtained for the method for solid samples. The results from sample analysis revealed that PFAAs were present in all solid samples at concentrations in the low to sub ng/g range and in all but one condensate and wastewater samples at concentrations in the low to sub ng/L range. The quantified concentrations were used to estimate the potential annual discharges of PFAAs from waste incineration plants to the environment. Emission scenarios via landfills, via wastewater treatment plants and to the atmosphere were considered. The main conclusion of this study is that waste incineration in Sweden is not a significant source of PFAAs to the atmosphere or to the environment in general.

This study focused on Atmospheric Deposition (AD) loading on Utah Lake. Utah Lake is susceptible to Harmful Algal Blooms (HABs) because of its large surface area to volume ratio, proximity to Great Basin dust sources, and various wind patterns from close mountain ranges that blow AD towards the lake. In this study, we continued the collection and analysis of AD samples that started in 2017 and 2018, while reporting additional 2019 and 2020 data. We constructed a sampler on Utah Lake itself, which allowed us to better estimate how AD loads were distributed over the lake. An interpolation assumption was made in the previous studies that the amount of AD decreases exponentially as it passes onto the lake from the shore. Results from 5 months of Bird Island AD sampling on Utah Lake indicate that this assumption was incorrect. We performed statistical comparison tests on 2 variables: (1) the difference in AD between 2 table heights at the same site and (2) the difference in AD between a filtered sample and an unfiltered sample. We were able to statistically conclude that there was no difference in AD between 1-meter and 2-meter tall sample tables and that filtered AD samples had as much as 3 times lower concentration than unfiltered AD samples. In 2017, the total AD loading was estimated to be, on the high end, approximately 350 tons of total phosphorous (TP) and 460 tons of dissolved inorganic nitrogen (DIN) (Olsen JM, 2018). After making some changes to the interpolation methods, Joshua Reidhead in 2018 estimated AD loads of 153 tons of TP and 505 tons of DIN (Reidhead, 2019). With no changes to the 2018 sampling methods, but using an updated interpolation method, we determined the AD results for Utah Lake in 2019 to be 262 tons of TP and 1052 tons of DIN. After adjustments to the sampling tables, the bucket filters, and incorporating the Bird Island sampler results, we calculated the 2020 AD loading totals to be 133 tons of TP and 482 tons of DIN on the lake.

Bulk atmospheric deposition samples were taken every two months for a year in 2009-2010 at two sites in northern Sweden and analyzed for a suite of legacy and emerging persistent organic chemicals including legacy organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs)  and novel flame retardants (NFRs).  To further investigate the urban occurrence and contribution to remote contamination of flame retardants, indoor air, ventilation system air, and dust were sampled in several microenvironments in Stockholm during the winter of 2012 for analysis of PBDEs, isomer-specific hexabromocyclododecane (HBCDD), and NFRs.  Outdoor air and soil samples were also sampled around the same time period for analysis of the same compounds.  Five emerging pollutants were detected in atmospheric deposition: the current-use pesticides trifluralin and chlorothalonil; and the NFRs 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (TBECH), 1,2-bis(tribromophenoxy)ethane (BTBPE), and Dechlorane Plus (DP).  A decrease in the fraction of the anti isomer of DP was observed at the more remote site, indicating isomer-selective degradation or isomerization during long range atmospheric transport.  The more remote site also received more total deposition of organic pollutants despite its receiving less precipitation.  Although PBDEs and emerging organic pollutants were detected, the bulk of the deposition consisted of PCBs and hexachlorocyclohexanes (HCHs) at both sites.   Several NFRs were identified in indoor and ventilation air samples including TBECH, pentabromotoluene (PBT), hexabromobenzene (HBB), 1,2-bis(pentabromodiphenyl)ethane (DBDPE), 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (EHTBB), and bis(2-ethylhexyl)-3,4,5,6-tetrabromo-phthalate (TBPH).  There was no significant difference between concentrations of contaminants in ventilation system air and indoor air indicating that the flame retardants included in this study reach the outdoor environment via ventilation systems.  Dust and outdoor air samples have only been analyzed for HBCDDs so far.  HBCDD concentrations in apartments, offices, and schools were lower than reported concentrations for other countries in similar microenvironments.   However, an enrichment of α-HBCDD compared to γ-HBCDD was observed in dust taken from near treated products in stores when compared to dust taken directly from those products.  Very low concentrations of HBCDDs were detected in outdoor air.

Les dépôts azotés (DA) mesurés à l'étage subalpin des Pyrénées sont compris entre 8 et 15 kg N ha-1 an-1, soit égaux ou supérieurs à la charge critique actuellement définie pour ces milieux et supérieurs aux estimations fournies par les modèles de chimie-transport. Au cours des soixante dernières années, les pelouses subalpines pyrénéennes sont devenues plus thermophiles et mésotrophes, plus riches en espèces et plus homogènes à l'échelle des Pyrénées. Le changement climatique (CC) et le cumul de DA ont réduit les contraintes abiotiques de ces habitats, favorisant l'installation d'espèces moins stress-tolérantes. Ces milieux piègent et conservent efficacement l'azote d'origine atmosphérique, même en contexte de CC. Des effets des DA sont détectables sur la végétation (%N, biomasse et recouvrement de certains groupes) avant d'être détectables dans le sol. Ces effets sont plus marqués en réponse aux apports dominés par l'ammonium plutôt que par le nitrate, et sont additifs ou compensatoires avec ceux du CC, mais rarement interactifs. / Atmospheric nitrogen deposition in the subalpine Pyrenees is in order of 8 to 15 kg N ha-1 yr-1, equivalent or higher than the actual critical load for these habitats and higher than chemistry-transport models' estimates. During the past six decades, Pyrenean subalpine grasslands became more thermophilous and mesotrophic, richer in species and more homogeneous at the regional scale. Climate change and cumulative nitrogen deposition reduced the abiotic constraints in these habitats, favouring the installation of less stress-tolerant species. These habitats trap and store efficiently nitrogen from deposition, even in a climate change context. Effects are visible in the vegetation (% of nitrogen, biomass and cover of some groups) before being visible in the soil. These effects are more pronounced following ammonium than nitrate dominated additions, and are additive or compensatory with the effects of climate change, but rarely interactive.