L’accroissement des dépôts de nitrate atmosphérique (NO3-atm) sur les bassins versants d’altitude, limités en ressources, entraîne des changements nets de disponibilité d’azote. Ces apports modifient la diversité biologique (végétation, plantes), les processus des sols liés à l’azote et conduisent à l’eutrophisation des cours d’eau. A terme, l’impact sur les populations humaines se traduira par la perte d’importants services fournis par ces écosystèmes (alimentation en eau, qualité du fourrage, contrôle de l’érosion, biodiversité). Si les effets des dépôts de NO3-atm sur les bassins versants pauvres en azote sont maintenant bien documentés, il n’en reste pas moins à comprendre les processus régissant la rétention de NO3-atm dans les écosystèmes de montagne. Pour ce faire, la variabilité spatio-temporelle de la répartition du NO3-atm dans tous les compartiments subalpins est ici étudiée en utilisant un traceur multi-isotopique (17O, 18O, 15N) du NO3-. L’importante proportion de NO3-atm dans les cours d’eau de montagne, tout au long de l’année et plus particulièrement à la fonte des neiges, laisse à penser que les bassins versants sont cinétiquement saturés en azote. La composition isotopique du NO3- dans les eaux de surface illustre la transformation rapide de l’ammonium de la neige et confirme que la fonte des neiges est une période cruciale du cycle de l’azote dans les montagnes enneigées. La proportion de NO3-atm dans les sols varie, quant à elle, en fonction du type d’occupation des sols et des propriétés biotiques et abiotiques afférentes. Le suivi de la végétation a montré une forte teneur en NO3-atm dans les tissus, par assimilation racinaire et foliaire. Ces avancées scientifiques permettront, à terme, de mieux comprendre comment les dépôts de NO3-atm affectent l’environnement. / Increasing rates of atmospheric nitrate (NO3-atm) deposition in nutrients poor mountainous regions have led to critical changes in nitrogen (N) availability, with consequences on biodiversity (plants, microbes), soils N turnover, and water nutrients status. This will ultimately affect human populations through the loss of critical ecosystem services (e.g., provision of clean freshwater, erosion control, biodiversity). If the impacts of NO3-atm deposition to N-limited basins are now well documented, little is known about the processes driving NO3-atm retention in subalpine ecosystems. In this context, new tools are necessary to better understand the fate of NO3-atm in mountains and to predict the mid and long-term ecological consequences of increasing NO3-atm deposition. This work uses a high-resolution multi-isotopic technique combining 17O, 18O and 15N signatures of NO3- in the different subalpine compartments to understand the temporal and spatial evolution of NO3-atm partitioning in a subalpine watershed of the French Alps. Subalpine streams elevated year-round exports of NO3-atm suggest that the watersheds are kinetically N saturated, especially after snowmelt. The isotopic composition of NO3- in freshwaters also points at the rapid processing of snow ammonium, confirming that snowmelt is “hot moment” for the N cycle in seasonally snow-covered catchments. The monitoring of soils reveals varying NO3-atm proportions depending on the land management treatments and implied biotic and abiotic characteristics. Two dominant subalpine plants showed high proportions of NO3-atm in organs acquired by both root and foliar uptake. These scientific breakthroughs will ultimately lead to a better understanding of how NO3-atm deposition affects the environment.

Atmospheric deposition is a marginally understood source of nutrient loadings to waterbodies. Atmospheric deposition occurs via wet (rain, snow) and dry (gaseous and particulate transport) pathways. Bulk atmospheric deposition is defined as the total deposition from both wet and dry pathways. Utah Lake is a shallow eutrophic freshwater lake located in central Utah, USA. Recent studies have shown atmospheric deposition to be a significant contributor to the nutrient budget of Utah Lake. This study presents the analysis using three different methods of six years' worth of wet atmospheric deposition samples from nine locations around the lake, though these samples do include some contribution from dry deposition. We present and compare nutrient loads and nutrient loading rates for total phosphorus, total in-organic nitrogen, and ortho-phosphorus. We conclude that wet atmospheric deposition contributed between 309 to 529 tons of total phosphorus, 1,166 to 2,078 tons of total nitrogen, and 106 to 201 tons of ortho-phosphorus to the lake during the study period. We extracted loading rates for the calendar year (in tons per year) and winter/summer month (in tons per month) from the data from each of the three methods of analysis. We show that wet atmospheric deposition is a significant pathway in which nutrients are transported to Utah Lake.

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Master of Science / Department of Civil Engineering / Natalie Mladenov / The Colorado Front Range of the Rocky Mountains contains undeveloped, barren soils, yet in this environment there is strong evidence for a microbial role in increased nitrogen (N) export. Barren soils in alpine environments are severely carbon-limited, and organic carbon (OC) is the main energy source for heterotrophic microbial activity and sustenance of life. Atmospheric deposition can contain high amounts of OC. Atmospheric pollutants, dust events, and biological aerosols, such as bacteria, may be important contributors to the atmospheric OC load. In this stage of the research we evaluated seasonal trends and annual loadings in the chemical composition and optical spectroscopic (fluorescence and UV-vis absorbance) signatures of wet deposition and dry deposition in an alpine environment, at Niwot Ridge in the Rocky Mountains of Colorado to better understand the sources and chemical characteristics of atmospheric deposition. Dry deposition was found to be an important source of OC to the alpine. Wet deposition contributed substantially greater amounts of dissolved ammonium, nitrate, and sulfate. There were also positive relationships between dissolved organic carbon (DOC) concentrations and ammonium, nitrate and sulfate concentrations in wet deposition, which may be derived from such sources as dust and urban air pollution. We also observed the presence of seasonally-variable fluorescent components in atmospheric samples that are different from aquatic dissolved organic matter (DOM). Finally, the quality of atmospheric organic compounds reflects photodegradation during transport through the atmosphere. These results are relevant because atmospheric inputs of carbon and other nutrients may influence nitrification in barren, alpine soils and, ultimately, the export of nitrate from alpine watersheds.

Submitted by Biblioteca de Pós-Graduação em Geoquímica BGQ (bgq@ndc.uff.br) on 2017-09-12T17:14:25Z No. of bitstreams: 1 Mestrado Perry I G.pdf: 1783499 bytes, checksum: 83cf5c6dcb288463ae336f1ff24698e8 (MD5) / Made available in DSpace on 2017-09-12T17:14:25Z (GMT). No. of bitstreams: 1 Mestrado Perry I G.pdf: 1783499 bytes, checksum: 83cf5c6dcb288463ae336f1ff24698e8 (MD5) / Universidade Federal Fluminense. Instituto de Química. Programa de Pós-Graduação em Geoquímica, Niterói, RJ / A APA-Petrópolis, localizada a 863m de altitude na Serra do Mar – RJ apresenta mais de 50% de sua área coberta por Mata Atlântica, que é considerada um “hot spot” em termos de biodiversidade mundial. Elevados fluxos de SO42-, NO3- e NH4+ estão sendo depositados na região e a origem principal desses poluentes é a Região Metropolitana do Rio de Janeiro (RMRJ) principalmente, situada a poucos quilômetros do extremo sudoeste da APA-PE. As principais espécies responsáveis pela acidez na água da chuva na APA-Petrópolis são H+, NH4+, SO42- e NO3-. O fluxo de deposição úmida de NH4+ é mais alto que o fluxo de NO3-, sendo o fluxo total (deposição seca e úmida) estimado em 14 kgN ha-1 ano-1. O excesso de N em ecossistemas tropicais acarreta uma série de danos à flora podendo levar à extinção de determinadas espécies. A fração marinha predominou para Na+, Mg2+ e Cl- e a não marinha para Ca2+, K+ e SO42-, sendo a contribuição desta fração maior durante o período úmido. É provável que as altas temperaturas estejam causando o aumento da transpiração da floresta neste período acarretando no aumento do transporte de íons de origem biológica pela ação dos ventos / The APA-Petrópolis, above 863m height in the Sea Mountain - RJ more than 50% of its area covered for Atlantic Forest, which is considered a “hot spot” of the world-wide biodiversity. High depoitions fluxes of exc-SO42-, NO3- and NH4+ have been found in this region and the major source of these pollutants seems to be the Metropolitan Region of Rio de Janeiro (RMRJ), situated near the southern boundary of the APA-Petrópolis. Those are the major chemical species controlling rainwater pH at APA-Petrópolis. The wet deposition flux of NH4+ was higher than that of NO3-. Total deposition (wet + dry) of inorganic N was estimated to be around 14,4 kgN ha-1 year-1. The excess of N in tropical ecosystems can possibly cause damages to the flora and could lead to the extinction of species. The sea-salt fraction predominated for Na+, Mg2+ and Cl- and the non-sea-salt fraction for Ca2+, K+ and SO42-. The non-sea-salt contribution predominates during the wet period

En raison de leur accumulation possible dans la glande thyroïde, les radio-isotopes de l'iode, 131I (t1/2 = 8,07 jours) et 129I (t1/2 = 15,7 106 ans), sont préoccupants pour la santé humaine. En raison de sa longue demi-vie, 129I est également d’une importance radio-écologique majeure du fait de son intégration potentielle au cycle biogéochimique naturel de son isotope stable (127I). Les forêts dont la surface couvre près du tiers du territoire en France et en Europe, se caractérisent par leur longévité, un haut niveau de recyclage de la biomasse et une forte influence sur les cycles hydrologiques et des nutriments. La végétation forestière peut intercepter puis recycler et accumuler les polluants et radionucléides émis dans l’environnement. Dans ce contexte, des axes de recherche ont été développés dans cette thèse afin de décrire qualitativement et quantitativement le cycle de l’iode et améliorer les prédictions à long-terme du comportement de 129I dans les écosystèmes forestiers.Les pluies constituent une source majeure d’iode pour les sols et la végétation forestière, les quantités apportées dépendant de la distance côtière et de la pluviométrie. La végétation modifie les quantités et la spéciation de l’iode apporté par les pluies. L'humus représente un compartiment d'accumulation provisoire d'iode associé à la matière organique. Ce compartiment constitue également une zone de réémission possible de l’iode par lessivage lors d’évènements pluvieux et/ou par volatilisation. Cette thèse a montré que les teneurs d'iode dans les sols forestiers dépendaient à la fois des apports atmosphériques et des chutes de biomasse, mais également de la capacité du sol à fixer l'iode. Ainsi, les conditions environnementales conduisant à une accumulation de matière organique et la présence d’(hydr)oxydes métalliques dans les sols favorisent la rétention de l’iode. A l’échelle de la placette forestière, le sol constitue le principal réservoir en iode (~99,9%). Du fait de la proportion d'iode au sein des arbres (< 0,03% du stock total en iode), les quantités d’iode recyclées par la végétation sont faibles, l’iode n’étant pas un oligo-élément pour les végétaux. Ainsi ces travaux de thèse ont permis de combler le manque de données relatives d’une part à la répartition de l’iode au sein des écosystèmes forestiers et d’autre part, aux processus de réémissions (lessivage et volatilisation) liés à la dégradation de la matière organique. Les données générées par cette thèse permettent de mieux appréhender la modélisation du cycle de l’iode dans cet écosystème forestier. / As radioisotopes of iodine may concentrate in thyroid gland, 131I (t1/2 = 8.07 days) and 129I (t1/2 = 15.7 106 years) are of health concern. 129I is of major radioecological importance because it can potentially integrate natural biogeochemical cycle of its stable isotope (127I) due to its long half-life. Forests, characterized by their longevity, a high biomass turnover and a strong influence on hydrological and nutrients cycles, can intercept, recycle and accumulate a significant amount of pollutants and radionuclides released into environment. In this context, research developed in this thesis had the purpose of correct long-term prediction of iodine behaviour in forest ecosystems.Rainfall appears to be a significant input flux of iodine in forest soils and vegetation, depending on coastal distance and precipitation amount. Forest canopy modifies quantities and speciation of iodine initially present in rainfall. Humus would act as temporary iodine accumulation layer through its association with organic matter. However, humus layer also behaves as potential iodine mobilisation source by leaching and/or volatilization. This thesis has demonstrated that iodine levels in soils depend both on its atmospheric and litterfall inputs, but also on the soil's ability to fix iodine. Thus, environmental conditions characterized by organic matter accumulation and presence of metal (hydr)oxides in soils promote iodine retention. Thereafter, soil is the main iodine reservoir at the forest plot scale (~99.9%). Given small amounts of iodine in the trees (<0.03% of the total iodine stock), recycling of iodine by vegetation is low, iodine being not an essential element for vegetables.This thesis contributes to fill some gaps in the knowledge of iodine distribution within forests and on the processes of iodine reemission related to organic matter degradation. Data generated by this thesis help to better understand the modeling of iodine cycle in this forest ecosystem.

No description available.

Persistent organic pollutants (POPs) are toxic chemicals that can be found in various matrices in all corners of the planet, including remote areas such as the Arctic.  Several POPs are known and monitored but given the abundance of new chemicals in commerce about which little is known, chemicals that may be new POPs are constantly being screened for. The use of flame retardants, particularly brominated flame retardants (BFRs), has been increasing for decades. PBDEs and HBCDDs are two types of BFRs that have historically been used in large volumes but recently faced legislative restrictions. However, in order to meet fire safety standards, these BFRs have been replaced by a variety of emerging flame retardants (EFRs) about which little is known especially concerning their toxicity, production volumes, and environmental behavior. The main purpose of this thesis was to investigate the occurrence and fate in indoor and outdoor environments of several EFRs and compare them with PBDEs, HBCDDs, and legacy POPs. Several indoor environments in the city of Stockholm, Sweden were sampled for dust, indoor air, and ventilation system air (Paper II).  Results from these samples revealed a number of EFRs that humans are exposed to and that are emitted from buildings through ventilation systems. These included DDC-CO, DBE-DBCH, PBT, HBB, EHTBB, and BEH-TEBP. PBDE levels seem to be declining compared to previous studies in Stockholm.  Outdoor air and soil were sampled across transects of Stockholm (Paper II) and Birmingham, United Kingdom (Paper III).  Results from these samples showed the presence of many of the same EFRs in the outdoor environment that were found in indoor environments.  Urban pulses in air were discovered for PBDEs in both cities and for some EFRs in Stockholm, indicating that the cities are sources of EFRs to the outdoor environment.  Atmospheric deposition samples were taken at two sites in northern Sweden (Paper I).  Three EFRs (DDC-CO, DBE-DBCH, and BTBPE) and two current-use pesticides (trifluralin and chlorothalonil) were identified, indicating these compounds’ potential for long range transport and global contamination.  Other legacy POPs such as HCH, PCBs, and PBDEs were measured in the deposition samples as well.  The bulk of deposition was comprised of HCH and PCBs with only minor contributions from PBDEs, chlordanes, and emerging compounds.  Finally, passive and active air sampling methods were compared for BFRs in offices in Beijing, China.  Some EFRs were identified in indoor air from China; however, BDE-209 was the most predominant compound found (Paper IV).  Air samples collected with passive samplers generally had measured FR concentrations within a factor of 2-3 of those collected with active samplers. The use of a GFF in the passive samplers resulted in concentrations of particle-bound contaminants such as BDE-209 that were more comparable to those in active samples. The positioning of the PUF in the passive samplers affected the sampling rates for gaseous compounds and particle retention on PUFs was shown to be a large source of uncertainty in passive sampling. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.</p><p> </p>

published_or_final_version / Applied Geosciences / Master / Master of Science

Trace metal contamination of the air-soil-tree system was examined in southern Quebec, where acid deposition and tree dieback have been recorded in high elevation forests. Mn pollution was emphasized due to its large emission from gasoline combustion in Canada. Airborne Cu, Mn, V, and Zn showed higher concentrations than those reported for other remote locations. Significant fluctuation in Mn concentrations during the winter-spring season was explored by air mass back trajectory analysis. The study suggested that high Mn concentrations resulted from the atmospheric long-range transport from Canadian industrialized and metropolitan regions. Metal concentrations in podzolic topsoils were generally higher than their world-wide average values. Concentrations of trace metals in balsam fir (Abies balsamea (L.) Mill) needles were below their suggested potential phytotoxic levels, except for Mn, which also increased with elevation. The scanning of needles with micro-PIXE showed no significant correlation between metal accumulation and epistomatal distribution on foliar surfaces. / Pathways of trace metals deposited in the soil-tree system were elucidated through application of $ sp{54}$Mn and $ sp{65}$Zn on shoot, bark, and soil surfaces in growth-chamber experiments with balsam fir seedlings. Uptake and accumulation by seedlings 70 days after application on the shoot surface was about 25-30% of the remaining activities for $ sp{54}$Mn and $ sp{65}$Zn. Less than 1% of absorbed isotopes was translocated from the bark surface to other plant organs, whereas more than 50% of the radioisotopes absorbed at the shoot moved to the rest of the seedling. Acidic wetness facilitated the metal absorption through tree surfaces. Downward movement of the radioisotopes in podzolic soils was documented, and accumulation in seedlings by root uptake was 5% of the remaining activity for $ sp{54}$Mn and 3% for $ sp{65}$Zn 70 days after application. No appreciable elemental migration from internal tissues to epicuticular wax layers was found, and the leaching ratio was below 0.5 and 1.0% for $ sp{54}$Mn and $ sp{65}$Zn, respectively. This study helps to understand the links between atmospheric deposition and the elevated levels of Mn in trees, and potential effects of acid deposition on the bioaccumulation of toxic metal pollutants in high elevation forests in southern Quebec.