Дисертації з теми "Seiches – Teneur en mercure"
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Minet, Antoine. "Bioaccumulation and effects of mercury in cuttlefish in the context of ocean acidification." Electronic Thesis or Diss., La Rochelle, 2022. http://www.theses.fr/2022LAROS039.
Повний текст джерелаThe common cuttlefish, Sepia officinalis, is a coastal cephalopod known for its eco physiological performance supported by a wide repertoire of behaviors that allows it, despite its short life cycle, to play a central role in food webs. However, it is also known to efficiently accumulate metallic elements such as mercury (Hg), a neurotoxic contaminant in its organic form (methylmercury; MeHg). Moreover, in the context of global changes, ocean acidification (OA) induced by the increase of CO2 emissions, can impact metabolism, development and the central nervous system, especially in young life stages. The present work therefore aims to study the effects of OA on Hg bioaccumulation and the effects of these two neurotoxicants (Hg and CO2) on behavior and cognitive performance in juvenile cuttlefish. In the first place, in-situ measurements showed that Hg accumulated in the brain of cephalopods in methylated form (MeHg). Moreover, experimental approaches using isotopic tracers (stable and radioactive) of Hg have shown that the accumulation of total Hg comes mainly from the assimilation of MeHg present in preys, compared to the accumulation of inorganic mercury (iHg) dissolved in seawater. This MeHg is then very strongly retained despite evidence of Hg demethylation processes in the digestive gland. Surprisingly, OA has no effect on the bioaccumulation efficiencies and metabolism of Hg. In terms of effect, behavioral assays showed that Hg and CO2, alone or in combination, did not impact visual acuity and predation performance in juveniles. However, both induced an increase in locomotor activity, compromised defensive behavior through, in particular, an alteration of disruptive coloration and a non-alignment of lateralization. Among the neural processes likely to be impacted by Hg and CO2, the GABAergic system was analyzed in the optic lobes but showed no obvious link with behavioral responses suggesting more complex effect processes. All of this work therefore questions the effects of future ocean conditions on juvenile’s cuttlefish, and more broadly the impacts on cephalopod populations
Breittmayer, Jean-Philippe. "Toxicité et accumulation du mercure chez la moule : caractérisation et quantification des principaux facteurs de variation." Aix-Marseille 2, 1986. http://www.theses.fr/1986AIX22058.
Повний текст джерелаCaille, Nathalie. "Mobilité et phytodisponibilité du mercure dans des dépôts de sédiments de curage." Vandoeuvre-les-Nancy, INPL, 2002. http://www.theses.fr/2002INPL027N.
Повний текст джерелаFoucher, Delphine. "Géochimie du mercure dans des sédiments estuariens et côtiers : cas de la Seine (France) et de la baie de Kaštela (Croatie)." Lille 1, 2002. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/2002/50376-2002-333.pdf.
Повний текст джерелаLacoue-Labarthe, Thomas. "Incorporation des métaux dans les oeufs de la seiche commune Sepia officinalis et effets potentiels sur les fonctions digestives et immunitaires." La Rochelle, 2007. http://www.theses.fr/2007LAROS217.
Повний текст джерелаLahaye, Virginie. "Les éléments traces chez les petits cétacés des eaux européennes : utilisation du cadmium et du mercure en tant que traceurs." La Rochelle, 2006. http://www.theses.fr/2006LAROS163.
Повний текст джерелаClaon, Jean Stéphane. "Exposition au mercure, à l'arsenic et au sélénium de l'écosystème et des populations riveraines de la lagune Aby (Côte d'Ivoire - Ghana) : recherche de bioindicateurs." Montpellier 1, 2004. http://www.theses.fr/2004MON13505.
Повний текст джерелаLaffont, Laure. "Fractionnement des isotopes stables de mercure dans un écosystème tropical en Amazonie bolivienne et dans les cheveux de populations humaines exposées." Toulouse 3, 2009. http://thesesups.ups-tlse.fr/854/.
Повний текст джерелаSamples of sediments, rocks, fish and human hair from the Bolivian Amazon basin, where gold-mining is active for decades, have been analysed by MC-ICPMS to study the stable isotopes fractionations of Hg. Evidence of mass-dependent (MDF) and mass-independent (MIF) fractionation have been observed in hair and fish samples. MIF is induced by photochemical reactions of Hg(II) and monomethylmercury (MMHg) in surface waters and MDF is observed only during the MMHg bioaccumulation process in organisms. Isotopic balance of Hg is improved thanks to sediments and rocks data showing a weak input of mercury by chemical weathering but significant atmospheric depositions of Hg(0) on soils. These first results obtained in hair and at a regional scale confirm that the stable isotopes of Hg constitute a powerful tool to trace biogeochemical processes and to evaluate mercury sources in living organisms
Bannerman, William Karikari. "Spéciation et distribution du mercure et de l'arsenic dans le bassin de la rivière Ankobra (Ghana) : Impact des mines d'or." Pau, 2003. http://www.theses.fr/2003PAUU3007.
Повний текст джерелаGold has been mined in the Ankobra river basin of Ghana for centuries. These activities emit mercury and arsenic whose impacts could be deleterious to the basin's ecosystem and the human population. To assess these impacts, mercury and arsenic were analysed in water, bed and suspended sediments, soils, edible vegetables and fish collected from the basin. Tota concentration and speciation analysis were done by single and hyphenated techniques of chromatography and atomic fluorescence spectrometry. High levels of mercury and arsenic were found in the proximities of the mining zones. The two elements are transported mainly in the aqueous phase of the river and they showed seasonal variation in both water and sediments. Detectable methylmercury in sediment averaged 1% of the total. Arsenic species detected in water and sediments were the inorganic forms. The sediments and fish were significantly contaminated in mercury
Abi, Ghanem Carine. ""Spéciation" des trois éléments trace mercure, plomb et cadmium dans les sédiments marins des zones côtières libanaises." Paris, AgroParisTech, 2008. http://pastel.paristech.org/5015/01/Thèse_Carine_Abi_Ghanem.pdf.
Повний текст джерелаKahoul, Mohamed. "Détection de la pollution mercurielle dans les sols et sédiments d'oued et relation avec la microflore fongique "in-situ" dans la région d'Azzaba (N. E. Algérie)." Université Joseph Fourier (Grenoble), 2002. http://www.theses.fr/2002GRE18008.
Повний текст джерелаHarris-Hellal, Jennifer. "Étude des interactions entre sols-mercure-composante microbiologique en Guyane française." Thesis, Paris Est, 2008. http://www.theses.fr/2008PEST0078.
Повний текст джерелаGuyanese soils contain high concentrations of mercury due to high geological background concentrations and locally to past gold-mining. The dynamics of this mercury is actually a major environmental and health preoccupation. In this particular ecosystem, the objectives of this thesis were to determine i) the importance of iron oxides in mercury distribution in soils, ii) the impact of microbial ferrireducing bacteria on the remobilisation of this toxic heavy metal, and iii) the impact of mercury pollution on the activity and genetic structure of soil microbial communities. This was assessed through two approaches, the first using soils sampled along a natural ferrallitic toposequence of a catchment basin, partly gold-mined up to 1950, near the village of Cacao. And the second using soils sampled from the forest of Patagai that records no past gold mining. Our results showed that the quantities of mercury decreased along the toposequence along with total iron contents, from the well drained oxisols to the hydromorphic talwegs. This happened in close relation to reductive conditions and watershed dynamics. The soil analyses combined to chemical extractions of amorphous and crystalline iron forms revealed the importance of the latter in mercury adsorption. These results logically brought us to study the impact of microbial activity, and more precisely bacterial iron reduction, on the remobilisation of mercury in these soils. This was carried out in reductive conditions similar to those encountered in natural conditions. In presence of available carbon, these experiments showed that ferri-reducing activity could solubilise significant quantities of iron, thus simultaneously mobilizing mercury. However, we did not detect an increase in dissolved mercury, presumably because it was re precipitated as HgS. Never the less, we observed variations in the amount of mercury associated to iron oxides during incubation. The second part of this work studied the impact of mercury on soil microbial communities. We approached this through a multidisciplinary study including chemistry, microbiology and molecular biology. Results confirmed that the effect of mercury depends on the concentration of Hg applied. While microbial biomass and numbers did not seem to be affected, the genetic structure as well as the functional diversity and carbon mineralisation were rapidly affected by high mercury concentrations (20 µg g-1 of soil). More over, we observed a rapid resilience in carbon mineralisation and functional diversity whereas genetic structure was durably modified. Complementary work enabled us to set up a multidimensional method to evaluate microbial community’s resistance and resilience to an environmental stress
Daye, Mirna. "Etude de la contamination par le mercure dans les milieux aquatiques : devenir et comportement biogéochimique, mise au point de méthodes d’analyse de trace du mercure." Thesis, Lille 1, 2013. http://www.theses.fr/2013LIL10074/document.
Повний текст джерелаMercury is a very particular element conferred by its high density and vapor pressure. It is a ubiquitous element in the environment and considered as global pollutant. Mercury is among the most hazardous environmental pollutants, given by its organic form, methylmercury (MeHg or CH3Hg). In natural waters, mercury is present at very low concentrations. For this reason, most analytical techniques do not achieve accurate direct measurement of Hg which necessitates preconcentration to meet their limit of detection. The first part of this study focuses on the development of analytical methods for the measurement of mercury by solid phase extraction. Two analytical methods have been developed; one based on the anion exchange mechanism using ICP-MS (Inductively Coupled Plasma Mass Spectrometry) and the other one based on the solid phase extraction of mercury using 5-phenylazo-8- hydroxyquinoline and detection by CV-AFS (Cold Vapor Atomic Fluorescence Spectroscopy). Part of this work also includes the distribution and biogeochemical behavior of mercury in rivers of the Deûle and Lys (Northern France). The results have showed high concentrations of total mercury (HgT) in the Deûle contaminated by a former smelter "Metaleurop". The concentrations of HgT measured in the Lys are much lower. Although Deûle sediments are highly burdened with HgT as compared to Lys sediments, much higher percentage of methylmercury is found in Lys River. Suspended particles are the major Hg carrier phase and transporters of Hg pollution from Deûle to Lys River
Laberge-Carignan, Audrey, and Audrey Laberge-Carignan. "Élaboration d'une stratégie analytique de dissolution du Hg et du Pb dans les aliments sur le terrain." Master's thesis, Université Laval, 2020. http://hdl.handle.net/20.500.11794/38101.
Повний текст джерелаLa nourriture issue de la chasse ou de la pêche comporte plusieurs nutriments essentiels à une bonne santé. Toutefois ces aliments peuvent aussi contenir des concentrations importantes en contaminants tel que le mercure et le plomb, qui posent un risque pour la santé. Pour guider les communautés qui basent leur alimentation sur la chasse ou la pêche, l’objectif global du projet est de développer une plateforme analytique permettant le suivi de la qualité alimentaire dans les environnements nordiques. Pour ce faire, une stratégie analytique de dissolution de la chair animale pouvant être employée à l’extérieur d’un laboratoire par des non scientifiques a été mise en place. Cette stratégie comporte l’échantillonnage, la mise en solution de la chair et la séparation des analytes pour effectuer leur analyse ainsi que le changement de matrice, en plus de la détection et de la quantification des analytes par fluorimétrie. Toutefois, puisque les systèmes de détection visés pour la plateforme sont en développement, une méthode de quantification du plomb et du mercure par ICP-MS/MS a aussi été développée. Cette stratégie analytique a été élaborée pour l’analyse de l’omble chevalier, un poisson consommé à l’année dans certaines communautés nordiques dans lequel les concentrations en contaminants sont très variables. Le processus analytique, de l’échantillonnage à l’obtention d’une solution mono élémentaire en passant par l’analyse ICP-MS/MS et la dissolution de la chair d’omble chevalier, sera décrit dans ce mémoire.
Fish and game meat contain different essential nutriments for a good health. However, it can also contain contaminants, such as mercury and lead, that pose a health risk. To guide the communities that base their diet on hunting or fishing, the main objective of the project is to develop a portable analytical platform that allows the monitoring of contamination by heavy metals of country food on the field. To this end, an analytical strategy for the dissolution of food flesh that can be deployed outside of the laboratory and used by non-scientists has been established. This strategy includes sampling, flesh dissolution, analyte separation and matrix exchange for the analysis in addition to fluorimetric detection and quantitation of the analytes. Since the quantification system for this platform is still under development, we therefore developed an ICP-MS/MS method to quantify lead and mercury in our food extracts. This method was developed to analyze arctic char, a fish consumed all year long in some northern communities and in which the contamination level can vary significantly. The analytical process from sampling to monoelemental analysis by ICP-MS/MS will be discussed in this document.
Fish and game meat contain different essential nutriments for a good health. However, it can also contain contaminants, such as mercury and lead, that pose a health risk. To guide the communities that base their diet on hunting or fishing, the main objective of the project is to develop a portable analytical platform that allows the monitoring of contamination by heavy metals of country food on the field. To this end, an analytical strategy for the dissolution of food flesh that can be deployed outside of the laboratory and used by non-scientists has been established. This strategy includes sampling, flesh dissolution, analyte separation and matrix exchange for the analysis in addition to fluorimetric detection and quantitation of the analytes. Since the quantification system for this platform is still under development, we therefore developed an ICP-MS/MS method to quantify lead and mercury in our food extracts. This method was developed to analyze arctic char, a fish consumed all year long in some northern communities and in which the contamination level can vary significantly. The analytical process from sampling to monoelemental analysis by ICP-MS/MS will be discussed in this document.
Laberge-Carignan, Audrey. "Élaboration d'une stratégie analytique de dissolution du Hg et du Pb dans les aliments sur le terrain." Master's thesis, Université Laval, 2020. http://hdl.handle.net/20.500.11794/38101.
Повний текст джерелаFish and game meat contain different essential nutriments for a good health. However, it can also contain contaminants, such as mercury and lead, that pose a health risk. To guide the communities that base their diet on hunting or fishing, the main objective of the project is to develop a portable analytical platform that allows the monitoring of contamination by heavy metals of country food on the field. To this end, an analytical strategy for the dissolution of food flesh that can be deployed outside of the laboratory and used by non-scientists has been established. This strategy includes sampling, flesh dissolution, analyte separation and matrix exchange for the analysis in addition to fluorimetric detection and quantitation of the analytes. Since the quantification system for this platform is still under development, we therefore developed an ICP-MS/MS method to quantify lead and mercury in our food extracts. This method was developed to analyze arctic char, a fish consumed all year long in some northern communities and in which the contamination level can vary significantly. The analytical process from sampling to monoelemental analysis by ICP-MS/MS will be discussed in this document.
Da, Silva Élodie. "Interactions "sol - vers de terre" et dynamique du mercure en Guyane française." Phd thesis, Université Paris-Est, 2013. http://tel.archives-ouvertes.fr/tel-00944329.
Повний текст джерелаTabouret, Hélène. "Recherche des marqueurs d'exposition aux contaminants et de fréquentation des habitats chez l'anguille Anguilla Anguilla de l'estuaire de l'Adour : de la réponse moléculaire à la microchimie de l'otolithe." Pau, 2009. http://www.theses.fr/2009PAUU3020.
Повний текст джерелаIn a context of decline of European eel (Anguilla anguilla L. ) and search for biological markers of habitat use and quality, a multidisciplinary approach was engaged on the Adour estuary and its associated wetlands. Two axes were developed. The first axe aimed at highlighting the successive presence of the species in different ecosystems based on the otolith elemental composition. The second aimed at the evaluation of the chemical pressure underwent by eels based on the contaminant bioconcentration in soft tissues and the early molecular response to the chemical stress. With a view to the analyses of otolith elemental composition taking into account the 3D structure, the low elemental concentration in the matrix and keeping the finest spatial resolution, four micro sampling strategies and multi elemental analyses using femtosecond laser ablation ICP-MS were tested (crater, 1D scan, 2D scan, flash ablation). The strategy showing the best compromise according to the objectives (continuous recording, multi elemental approach) was applied on otolith of yellow eels from the Adour. The simultaneous use of Sr and Ba profiles, after validation, represents a new tool, easy, fast and reliable for the reconstruction of freshwater and brackish ecosystems use by eel avoiding misinterpretation due to vaterite inclusions. Three major behaviors were highlighted on the Adour: a residency in brackish water, a residency in freshwater and nomad behavior. The last one is illustrated by a shift to brackish water after three to four years spent in freshwater. Simultaneously, the study of inorganic and organic contamination of eel soft tissues showed that sampled wetlands are moderately contaminated. These results were confirmed by the first estimation, in wild conditions, of the early response to the chemical stress using the hepatic expression of CYP1A1 gene measured by real time RT-PCR. Conversely, in the downstream part of the Adour estuary, Hg loads in eels, especially methyl mercury, and PCBs analyses indicate values that need further investigations considering the European norms of consumption. The comparison of the different markers used (heavy metal and organochlorinated compounds contamination of soft tissues, condition index) support a lower quality of the estuary despite higher eel growth rate on this site. This study supports the use of numerous markers in integrated studies in order to understand and specify the relationships between eels and their continental growth zones
Castelle, Sabine. "Spéciation et réactivité du mercure dans le système fluvio-estuarien Girondin." Thesis, Bordeaux 1, 2008. http://www.theses.fr/2008BOR13645/document.
Повний текст джерелаThis study presents a first quantitative assessment of the main processes controlling the Hg cycle in the Gironde Estuary (speciation, distribution, fluxes, dynamics) affected by historical polymetallic pollution. Selective extractions on sediments and suspended solids showed that in the Lot-Garonne-Gironde fluvial-estuarine system ~70% of total Hg fluxes (100-800 kg yr-1) are associated with organic matter and/or sulphides. Sampling of the different environmental compartments (water, air, sediments) addresses spatial and temporal variability at multiple scales, covering the major estuarine geochemical gradients. Longitudinal profiles (9 cruises) over the salinity gradient showed a 2-5 times increase in dissolved Hg concentrations (baseline ~1 ng L-1) in the Maximum Turbidity Zone (MTZ), mainly attributed to microbial degradation of particulate organic matter, a major Hg carrier phase. Dissolved MeHg (MeHgD)levels are generally low (<0,05 ng L-1) but may reach up to 0.5 ng L-1 under very turbid conditions. The relation between MeHgD and turbidity was attributed to dissolution of particulate carrier phases and/or in situ methylation of Hg (sediment or water column), MeHg photodegradation being negligible due to turbidity. A systematic increase in particulate MeHg near the estuary mouth suggests uptake and accumulation by phytoplankton, especially from May to September when light conditions allow intense primary production. In surface sediment (0-20 cm; dredged and non-dredged; subtidal and intertidal), MeHgD concentrations increased parallel to diagenetic reduction of Fe-phases and sulphate, suggesting biotic Hg methylation and/or MeHg release by Fe oxyhydroxyde dissolution. Incubation experiments in undisturbed sediment using stable isotope (199Hg) spikes suggest an average methylation rate of 0.012 %-Hg methylated.h-1. Diffusive exportation of dissolved Hg and MeHg into the water column at the whole estuary scale has been evaluated to 0.1 kg.yr-1and 0.08 kg.yr-1,respectively. These fluxes are negligible compared to fluvial inputs (35 kg.yr-1 and 1.4 yr.an-1). Dredging-related re-suspension of reduced sediment and pore water may recycle ~1100 kg of Hg and 3.2 kg of MeHg in the water column. This may locally and temporarily modify Hg distribution in the water column, but does not seem to modify the estuarine Hg balance. Diurnal cycles of dissolved gaseous mercury (DGM; mostly Hg°) concentration in surface water have been attributed to photo-reduction of Hg(II). However, turbidity may efficiently reduce light penetration and DGM production. Therefore, the DGM cycle in turbid estuaries depends on seasonal variations in MTZ intensity and position. The Gironde Estuary is a Hg° source to atmosphere in summer, but may turn into a sink during turbid periods in winter. The annual Hg° evasion (~4 kg.yr-1) is counterbalanced by dry and wet deposition (5-8 kg.yr -1)
Yang, Xu. "Une étude expérimentale de la photoréduction du mercure atmosphérique dans des eaux de pluie." Thesis, Toulouse 3, 2019. http://www.theses.fr/2019TOU30094.
Повний текст джерелаAtmospheric Hg photoreduction could take place in both gas- and aqueous phase. Rainwater Hg(II) photoreduction rates, under fully sunlit conditions, are an order of magnitude slower than the optimized maximum in-cloud photoreduction rate of > 1.0 h-1 in global Hg models. Atmospheric aqueous Hg photoreduction is too slow to be dominant reduction pathway. Atmospheric gaseous HgBr2, HgCl2, HgBrNO2, HgBrHO2 forms, scavenged by aqueous aerosols and cloud droplets, are converted to Hg(II)-DOC forms in rainfall due to abundant organic carbon in aerosols and cloud water. Computation of gas phase photolysis rates of Hg(II) compounds can be fast, and is fast enough to rebalance the modeled atmospheric Hg cycle between Hg(0) oxidation and Hg(II) reduction
Fezai, Fatma. "Élaboration d'un capteur électrochimique basé sur une interface mixte film de diazonium / nanoparticules d'or pour la détection des traces de mercure(II) dans les eaux naturelles." Thesis, Toulouse 3, 2019. http://www.theses.fr/2019TOU30223.
Повний текст джерелаMercury (Hg) is highly toxic metal originating from natural sources and mainly from anthropogenic processes. It can bioaccumulate all along the food chain and causes severe diseases being thus lethal. Thus, it is of critical importance to ensure continuous Hg(II) monitoring for health and environmental protection. Classical Spectroscopic techniques are routinely used for Hg(II) determination. Although they offer good sensitivity and selectivity, they involve complex procedures and expensive material, which limit their use for on-site analysis. In this context, electrochemical sensors present excellent candidates for in situ Hg(II) trace analysis, taking in account their numerous advantages compared to spectroscopic techniques: easier handling, simple procedure, low energy consuming, low cost material and portability. This work presents a new electrochemical approach aiming to conceive and optimize an electrochemical Hg(II) sensor based on the functionalization of a glassy carbon electrode with gold nanoparticles (AuNPs) and diazonium salts in order to enhance the sensor lifetime. The gold nanoparticles were directly electrodeposited on the glassy carbon electrode, previously functionalized by diazonium salts. The mixed interfaces were then characterized using different electrochemical and spectroscopic techniques. An activation step was finally performed prior to mercury detection. The analytical performances of the sensor (stability, sensitivity, selectivity) towards mercury detection were evaluated using different amounts of Hg(II)
Marusczak, Nicolas. "Etude du transfert du mercure et du méthylmercure dans les écosystèmes lacustres alpins." Phd thesis, Université de Grenoble, 2010. http://tel.archives-ouvertes.fr/tel-00553704.
Повний текст джерелаZysk, Janusz. "Modeling of the atmospheric dispersion of heavy metals over Poland." Thesis, Paris Est, 2016. http://www.theses.fr/2016PESC1169/document.
Повний текст джерелаModelling of atmospheric transport of heavy metals emitted from Polish power sectorMany studies have been conducted to investigate the atmospheric heavy metals contamination and its deposition to ecosystems. The increasing attention to mercury pollution has been mainly driven by the growing evidence of its negative impacts on wildlife, ecosystems and particularly human health. Lead and cadium are also toxics which are being emitted into the atmosphere by anthropogenic as well as natural sources. The harmful influence of these three heavy metals was underlined in the Aarhus Protocol on Heavy Metals of 1998. The Parties of this protocol (including Poland) are obligated to reduce emissions, observe the transport and the amounts of lead, mercury and cadmium in the environment.Poland is one of the biggest emitter of mercury, lead and cadmium in Europe mainly due to emission from coal combustion processes. Therefore in Poland, research efforts to study the heavy metals emission, atmospheric transport, concentration and deposition are extremely important. The objectives of this work were twofold:• The practical objective was to develop and run a model to represent the atmospheric dispersion of mercury and to implement it in the air quality modelling platform Polyphemus.• The scientific objective was to perform heavy metals dispersion studies over Europe and detailed studies of the impact of the polish power sector on the air quality regarding mercury, cadmium and lead.To meet the declared aim, a new mercury chemical model was implemented into the Polyphemus air quality system. The scientific literature was reviewed regarding mercury chemistry and mercury chemical models. It can be concluded that the chemistry of mercury is still not well known. The models also differ in the way of calculating the dry and wet deposition of mercury. The elemental gaseous mercury ambient concentrations are evenly distributed, on the contrary, high variations in the spatial gradients of reactive gaseous and particulate forms of mercury air concentrations and deposition fluxes were noted.This study shows that many components of the developed model have crucial impacts on the results. In the model of mercury chemistry, the most effective pathway in the gaseous phase are the oxidation of gaseous elemental mercury by hydroxyl radical, ozone and most of all bromine oxide radicals, while in the aqueous phase the reduction reactions of elemental mercury dominate. These reactions have a crucial influence on the mass balance of reactive mercury, but a rather low influence on gaseous elemental mercury (GEM). In this model, dry deposition of gaseous elemental mercury is the prevailing process for removing mercury from the atmosphere. Dry deposition of GEM over land is equally distributed, due to almost uniform ambient concentrations. The relatively high dry deposition flux of gaseous elemental mercury has a huge influence on the presented results and differs significantly from other models where the dry deposition of GEM is often not taken into account. It was also shown that a change in the calculation of the scavenging coefficients or representative raindrop diameter for in-cloud scavenging has a significant impact on the amount of wet deposited mercury.The detailed results show that the Polish power sector can be responsible for up to 80% of wet deposited mercury near large emission sources. The contribution from national sources over whole Poland reaches 21% during the winter heating season when large quantities of coal are burned in the domestic sector and additionally the power sector activity is at its highest. The impact of emissions of cadmium and lead from the power sector is lower compared to the obtained results for mercury. The modelling results showed maximal impacts of 30% and 10% for cadmium and lead near large power sector sources on the ambient concentrations and deposition. Wider measurements of heavy metals are very much needed
Ferrat, Lila. "Réactions de la Magnoliophyta Marine Posidonia Oceanica en réponse à des stress environnementaux." Corte, 2001. http://www.theses.fr/2001CORT3063.
Повний текст джерелаAlbert, Céline. "Exposure of Arctic seabirds to pollutants and the role played by individual migratory movements and non-breeding distribution." Thesis, La Rochelle, 2020. http://www.theses.fr/2020LAROS020.
Повний текст джерелаThe Arctic, even far from intensive human activities, is contaminated by pollutants emitted at Northern mid-latitudes. Because of their physico-chemical characteristics, pollutants are transported over large distances through atmospheric or oceanic currents. Among them is mercury (Hg), a naturally occurring and non-essential trace element whose emissions increased since the 19th century because of human activities. This neurotoxic negatively impacts animals’ health and induces behavioral changes, reproduction issues and in the most extreme case, death. The marine environment is particularly sensitive to Hg, which incorporates the food chain (under is toxic and methylated form – MeHg) in which its concentration increases from one trophic level to the other (e.g. biomagnification process) and accumulates within organisms (e.g. bioaccumulation process). Hence, long-lived top predators like seabirds, found at the end of the food chain usually show some of the highest contamination to Hg. They are commonly and efficiently used as bio-indicators of the health of their environment. Most of the current knowledge about Hg contamination in Arctic seabirds focused on the breeding period during which Hg was found to spatially vary, with usually higher Hg concentrations in the Canadian Arctic. During this period, which represents a part of the year only, seabirds aggregate in colonies for reproduction where they are more easily accessible. However, at the end of this period, seabirds migrate to overwinter mostly in open seas, outside of the Arctic. A previous study on a little auk (Alle alle) population breeding in East Greenland found that Hg concentrations were higher during the non-breeding period than during the breeding period, with carryover effects on the following reproduction. In the present doctoral work, based on a multi-species and multi-colony approach, we studied winter Hg exposure and the role of seabird migration in their contamination to Hg at large spatial scale. We found a seasonality in Hg concentrations allowing us to extend the results found in little auks to several species and at a larger spatial scale. We also found that this seasonality was spatially different with some of the highest variations for seabirds breeding in the West Atlantic (West Greenland and Canadian Arctic). We therefore proposed that such variations were due to seabird’s migration and the areas they overwintered at. To test such hypotheses, we used seabirds as bio-indicators of winter Hg contamination through the North-Atlantic Arctic. More specifically, we combined Hg measurements with geolocators devices to track the spatial origin of winter Hg contamination. We found an east-west increase in Hg concentrations allowing us to extend the results found during the breeding period to the winter period, through the entire North-Atlantic Arctic marine region. Results of the present doctoral work allow us to conclude that beyond migration, seabird distribution during the breeding and non-breeding periods drive their contamination to Hg
Angot, Hélène. "Cycle atmosphérique du mercure dans des zones reculées de l’Hémisphère Sud : cas de la couche limite marine subantarctique et du continent Antarctique." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAU014/document.
Повний текст джерелаMercury (Hg) is a metal emitted by both natural and anthropogenic sources. It is of global concern owing to its long-range atmospheric transport, its persistence in the environment, its ability to bioaccumulate in ecosystems, and its negative effects on human health. Large uncertainties associated with atmospheric models – that trace the link from emissions to deposition of Hg onto environmental surfaces – arise as a result of our incomplete understanding of atmospheric processes (oxidation pathways, deposition, and re-emission) and of the scarcity of monitoring data at a global scale. The aim of this PhD work is to improve our understanding of the atmospheric Hg cycling at three remote sites of the Southern Hemisphere: Amsterdam Island (AMS) in the Indian Ocean, Concordia (DC) on the East Antarctic ice sheet, and Dumont d’Urville (DDU) on the East Antarctic coast. Data acquired at AMS suggest a limited atmospheric reactivity of Hg in this part of the globe. The advection of polluted continental air masses being scarce, AMS is a key site for the long-term monitoring of the atmospheric background in the Southern Hemisphere mid-latitudes. Data acquired in Antarctica highlight the occurrence of unprecedented processes in the atmosphere and at the air-snow interface. Due to katabatic winds flowing out from the East Antarctic ice sheet down the steep vertical drops along the coast, processes observed at DC influence the cycle of atmospheric Hg on a continental scale. These scientific breakthroughs will ultimately lead to improved global transport and deposition models
Kadlecova, Milada. "Contamination mercurique des sédiments et cours d'eau du nord de la France et de la République Tchèque." Thesis, Lille 1, 2011. http://www.theses.fr/2011LIL10148/document.
Повний текст джерелаMercury (Hg) is naturally occurring toxic element; however global mercury emissions are dominated by anthropogenic sources. The global cycle of mercury has seen an increase in mercury deposition, especially in aquatic ecosystems, since the beginning of the industrial revolution. First part of the thesis summarizes the source of mercury, its properties and toxicity from the general point of view, but also the current state of knowledge on the biogeochemical cycle of mercury and in particular behaviour of mercury inside the sediments of the aquatic environment and factors influencing its transformation into methylated form. The sediment in aquatic systems may acts as the ultimate sink, where mercury in its various complexes is deposited. The mercury in sediments can then be converted to its more toxic organic form, methylmercury (MeHg), by the transformation processes controlled by various physical, chemical and biological factors. More over remobilization of mercury species from sediments is possible due to diffusion and resuspension and so sediments may act as potential source of mercury for aquatic biota. Bioaccumulation and biomagnifications can then continue up the food chain where humans, among other animals, consume the organic mercury. It is clear that determination of total mercury is not sufficient to understand its fate in the environment; determination of MeHg provides very useful additional information. The sensitive and precise analytical method for MeHg determination is necessary. The methodological part of the thesis deal with the methods for determination of mercury species in sediments. The method for methylmercury determination in sediments using automated Headspace sampler equipped with Trap and coupled with Gas Chromatography and Atomic Fluorescence Detector was developed and is define. The special attention is also given to the necessity of clean sampling procedures and the proper storage and pre-treatment of the samples and the field study of Hg distribution in sediments. The mercury contamination of sediments from the South Moravia and Northern France are compared. The mercury species and other elements (Fe, Mn, S) were analysed in sediments and/or pore water and/or surface water collected from the sampling sites in the Deûle and Lys River (France) and Jihlava and Morava River (Czech Republic). In order to better assess the mercury contamination of aquatic ecosystem, the pore water concentration could be evaluated to understand the availability of mercury from sediment. The use of diffusive gradient in thin film (DGT) technique is applied to measure pore water mercury concentration in river sediments. Different resins gels for mercury determination are used: Spheron-Thiol, Duolite GT-73 and TiO2. River Deûle act as a sink for enormous anthropogenic Hg from the industrial activities and is considered as a potential significant source of methylmercury to the surrounding environment. The last part of thesis deals with the application of well-established isotope experiments to study methylation/demethylation processes in sediments of Deûle River. For this purpose, species-specific isotopically enriched tracers in the form of inorganic mercury IHg (199Hg) and MeHg (201MeHg) have been added to the sediment slurries. Mercury labelled species were used as the tracers to follow their chemical fate and calculate the extent of the transformation reaction yield occurring during the 24 hours experiment. This experiment methodology is refined by applying advanced matrix algebra to resolve the contributions of several different enriched stable isotope species specific tracers to the isotope pattern found, making the calculation of methylation/demethylation rates possible
Houssard, Patrick. "Variations des concentrations en mercure dans les réseaux trophiques marins de l'Océan Pacifique Sud : état des lieux, caractérisation des sources et relations avec la dynamique trophique et physique du milieu." Thesis, Nouvelle Calédonie, 2017. http://www.theses.fr/2017NCAL0001/document.
Повний текст джерелаMercury is a naturally distributed heavy metal which is characterized, under its organic form (monomethylmercury; MMHg), by its bioaccumulation in living organisms and its biomagnifications along food chains. Since the awareness of MMHg neurotoxicity, lots of research works have focused on understanding where and how MMHg is formed and transmited to marine food webs. Those questions are keys in order to anticipate how MMHg, in commercially fish species, will respond in a context of increasing mercury emissions and climate change.This work is part of this approach by studying total mercury spatial variations from muscle tissue of three tuna species: bigeye, albacore and yellowfin tuna, captured within the south Pacific Ocean. Every tuna species demonstrated a consistent and similar spatial trend, with higher total mercury concentrations in the southwest and lower concentrations in the western equatorial Pacific. This spatial trend seems to be in accordance with varying tuna diet linked to the thermal features of the water column. By combining archival tagging data and nitrogen stable isotope analysis, we showed that the deepening of bigeye tuna vertical habitat around New Caledonia might allow them to forage on deeper and MMHg enriched preys. Additionnaly, dissolved MMHg profiles in the southwest Pacific suggest higher methylation processes in the epipelagic zone leading, possibly, to higher MMHg bioavailability for marine food chains.This study highlighted the key role of tuna trophic ecology and particularly foraging depth in their MMHg exposure. Those features have to be considered in future studies evaluating food webs contamination at a spatial or temporal scale
Renedo, Elizalde Marina. "Sources and fate of methylmercury in the Southern Ocean : use of model seabirds and mercury stable isotopes." Thesis, La Rochelle, 2017. http://www.theses.fr/2017LAROS031/document.
Повний текст джерелаDespite their distance from industrial pressure, marine southern and Antarctic environments are contaminated by worldwide distributed pollutants, such as mercury (Hg), through atmospheric transport and oceanic currents. So far, Hg contamination pathways in the Southern Ocean remains poorly understood, particularly in the Indian sector, and new studies are required to elucidate its fate and impact in these regions. Seabirds, as top predators of marine food webs, are exposed to elevated concentrations of biomagnified methylmercury (MeHg) via dietary intake and moreover, they forage in the different marine compartments both in spatial and depth terms. Therefore, they are considered as effective bioindicators of Hg environmental contamination and the good knowledge of their ecological characteristics permits their application for tracing Hg in such remote environments otherwise of difficult access. The main objective of this doctoral work is the characterization of the exposure pathways of the MeHg accumulated in model seabirds and the identification of the processes involved in the Hg biogeochemical cycle in the Southern Ocean (from Antarctic to subtropical waters). The proposed methodological approach consisted on the combination of Hg isotopic composition and Hg speciation in tissues of a precise selection of seabirds of the Southern Ocean. In a first step, the evaluation of tissue-specific Hg isotopic signatures was accomplished notably in blood and feathers, as they can be non-lethally sampled. In chicks, both tissues can be effectively and indifferently used for biomonitoring of local contamination using Hg isotopes, whereas in adults each tissue provides access to different temporal exposure : blood at recent scale (i.e. exposure during the breeding period) and feathers at annual scale, thus providing complementary isotopic information at the different stages of seabird annual cycle. A second part was focused on the exploration of MeHg sources in four penguin species within a same subantarctic location, the Crozet Islands. Hg isotopes effectively discriminated the four populations and species-specific foraging habitats and latitudinal movements were found the main factors determining their exposure to distinct environmental MeHg sources. In a third part, Hg isotopes were investigated in two ubiquitous seabird models (skua chicks and penguins) over a large a latitudinal scale from Antarctica to the subtropics. Latitudinal variations of Hg isotopic values (δ202Hg, Δ199Hg) appeared to be influenced by different extent of photochemical processes and other biogeochemical pathways such as Hg reduction, and methylation/demethylation processes, as well as trophic or metabolic processes
Mattio, Elodie. "Développement de systèmes d'analyse en flux imprimés en 3D pour le dosage de Pb, Cd et Hg dans les eaux." Thesis, Aix-Marseille, 2018. http://www.theses.fr/2018AIXM0361.
Повний текст джерелаMetals determination in aqueous samples is a major challenge nowadays, in the light of their high toxicity and their numerous emission sources into the environment. In this context, the development of on-line and low-cost analytical systems allows to carry out automated on-site measurements. Three metals (lead, cadmium and mercury) have been targeted in this study. 3D printing has been used in this study to reduce fabrication costs and to allow a tailor-made conception of the units. The developed flow systems in this study are based on the same analytical methodology: first, the sample is photo-oxidized to extract targeted metals from organic and mineral matrix of the sample. Then, metals are preconcentrated on a solid phase, then eluted and detected by UV-Visible or fluorescence spectroscopy. The choices of preconcentration solid phases, eluents, and detection reagents are decisive for the selective and sensitive characterisation of each metal. The first developed system concerns lead analysis, and consists of three 3D printed units, which contain a resin column, a mixing coil, and a spectroscopic flow-cell. The second system for lead and cadmium determination contains a 3D printed lab-on-valve with eight ports, two resin columns, and a mixing coil with baffles. Finally, the third system includes a 3D printed unit whose surface has been modified by grafting a molecule with high affinity for mercury (dithizone carboxylate). This 3D printed unit provides a selective extraction of mercury after modification of its surface. The systems thus developed allow to explore the possibilities of 3D printing for the development of more complex flow systems
Da, fonseca Clemens Stéphanie. "Spéciation du mercure dans les produits de la pêche par double dilution isotopique et chromatographie en phase gazeuse couplée à un spectromètre de masse à plasma induit (GC-ICP-MS)." Phd thesis, AgroParisTech, 2011. http://pastel.archives-ouvertes.fr/pastel-00753697.
Повний текст джерелаLemaire, Jérémy. "Mercury contamination in caimans from French Guiana, bioaccumulation and physiological effects." Thesis, La Rochelle, 2021. https://tel.archives-ouvertes.fr/tel-03716076.
Повний текст джерелаMercury (Hg) is a global environmental contaminant that affects ecosystems. It has the particularity to biomagnify through the food web, and to bioaccumulate especially in tissues of top predators. Mercury has been identified to have detrimental effects on human and wildlife. Top predators from tropical ecosystems are particularly affected by Hg contamination due to artisanal small scale gold mining, which uses massive amounts of Hg in the gold extraction process. Crocodilians are top predators of tropical ecosystems and have been identified to accumulate high concentrations of Hg in their tissues. They are potentially good candidates to monitor Hg contamination, as they are long-living animals with low metabolic, and high tissue conversion rates, which favours the bioaccumulation of Hg. Additionally, they have a large repartition over tropical and sub-tropical ecosystems, which make large-scale Hg evaluation possible. My doctoral work focuses on the four caiman species that are present in French Guiana (the Black caiman Melanosuchus niger, the Dwarf caiman Paleosuchus palpebrosus, the Smooth-fronted caiman Paleosuchus trigonatus and the Spectacled caiman Caiman crocodilus). First, I have worked on Hg variation across different tissues obtained by minimally invasive methods, and investigated the influence of morphology and feeding ecology (by using stable isotope method) on Hg contamination in caimans. Second, I have investigated the impact of Hg contamination on physiological mechanisms, and the maternal transfer and its effects on neonates
Fu, Xiaojian. "Coupure Hydraulique et Potentiel de Production en Gaz de Réservoirs de Grès « Tight » : Etude Expérimentale." Thesis, Ecole centrale de Lille, 2013. http://www.theses.fr/2013ECLI0021/document.
Повний текст джерелаSo-called tight gas reservoirs are constituted of low permeability sandstones, which petro-physical properties may interfere with proper gas recovery. They have a low absolute permeability (below 0.1 mD under ambient conditions), a porosity lower than 10%, and a strong sensitivity to in situ stresses as compared to conventional reservoirs. Moreover, an important transition zone is observed in situ, where partial water saturation is present, and which may extend over several hundred meters over the free water table. In such zone, where water saturation is on the order of 40-50%, neither gas nor water seems sufficiently mobile for industrial extraction: this is the permeability jail. Our aim is to assess their actual petro-physical properties, namely porosity, gas permeability under varying hydrostatic stress and water saturation level, in relation with sandstone microstructure. Accessible water porosity measured is between 2 to 12%. The intrinsic permeability to gas did not appeared related to the porosity of samples. A high sensitivity of gas permeability to confinement was observed. Two families of samples were identified. The more permeable samples (permeability between 100-1000 μD), are relatively insensitive to confinement and their relative permeability decrease for water saturation higher than 50%. Less permeable samples appear much more sensitive to mechanical loading and saturation.Methods classically used in oil and gas industry based on the interpretation of mercury intrusion porosimetry tests have also been used to evaluate relative permeability and compared with experimental measurements
Duval, Bastien. "Ecodynamics of trace metals and metalloids in Pyrenean lakes in relation to climate change and anthropogenic pressure." Thesis, Pau, 2020. http://www.theses.fr/2020PAUU3046.
Повний текст джерелаThe management and conservation of Pyrenean high mountain lakes within the current context of climate change and increasing anthropogenic pressure require detailed knowledge of their biogeochemical functioning. In this doctoral thesis, five sampling campaigns were carried out (2017-2019) in more than 20 alpine lakes. The analysis of water samples allowed us to study the occurrence, the depth profiles, the geographical distribution and the seasonal trends of a large array of physico-chemical and biogeochemical parameters. Specifically, the cycle of carbon dioxide (CO2) and the fate of Potentially Harmful Trace Elements (PHTEs) were investigated. The mercury (Hg) was specially studied through the development of an analytical procedure for the measurement of trace concentrations in natural waters and through biogeochemical investigations on the distribution and the fate of Hg species in the water column, as well as in sediment archives.The new and robust procedure developed in this work to measure the total alkalinity (TA) and the dissolved inorganic carbon (DIC) allowed us to determine the other two parameters of the CO2 system, the pH and the fugacity of CO2 (fCO2). The bedrock characteristics of the watershed appear to be the most important parameters influencing the acid status of the studied lakes. Moreover, obtained fCO2 values indicate that lakes are sources of CO2 for the atmosphere.The measurement of various physico-chemical parameters allowed us to discriminate and classify the studied lakes according to their water geochemistry, highlighting the importance of the trophic status of the lakes, the geological background and the atmospheric inputs. The occurrence, sources and behaviour of the PHTEs were investigated with evidence of a contrast between geological and atmospheric inputs. Intensive monitoring revealed some PHTEs to be highly sensitive to environmental changes such as temperature and redox conditions.Monitoring natural concentrations of total Hg in aquatic systems remains a difficult challenge and there is a need for the development of low cost and easy handling analytical methods. The method for analysis of trace Hg concentrations developed and optimized in this work was successfully operational and exhibits a suitable limit of detection and an excellent reproducibility. Hg speciation results in the water column demonstrated the pristine state and the dynamic of the Pyrenean lakes. The homogeneity in the non-gaseous total Hg concentrations in the studied lakes confirmed the absence of local sources and the potential use of these ecosystems as sentinels of regional to global Hg contamination. While inorganic mercury (iHg) did not show seasonal variations, monomethylmercury(MMHg) was significantly higher in autumn 2018 and dissolved gaseous mercury (DGM) varied strongly within and among lakes. In-situ experiments confirmed the conditions that promote Hg methylation (stratified anoxic waters), demethylation and photoreduction (intense UV light).The historical Hg record in sediment archives highlighted temporal trends in Hg accumulation rates (HgARs) with a progressive increase since the 16th Century and the industrialization, mirroring the Hg production in Almadén mines (Southern Spain). Besides, Hg stable isotopes allow the identification of distinct anthropogenic sources as well as past climate variability.Overall, environmental changes in lake ecosystems, induced by either climatic conditions (temperature, light intensity) or anthropogenic pressure (atmospheric inputs, eutrophication, atmospheric CO2) are likely to produce significant impacts among CO2, specific PHTEs and Hg biogeochemical cycles in mountainous ecosystems
Stupar, Yohana Vanesa. "Trends and rates of mercury and arsenic in sediments accumulated in the last 80 years in the climatic-sensitive Mar Chiquita system, Central Argentina." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2013. http://tel.archives-ouvertes.fr/tel-00920306.
Повний текст джерелаMartinez, Duenas William Andrés. "Modèle spatial de la charge de mercure présent dans le biofilm épiphyte du littoral du lac Saint-Pierre, Fleuve Saint-Laurent (Québec)." Mémoire, 2006. http://www.archipel.uqam.ca/2806/1/M9584.pdf.
Повний текст джерелаComte, Irina. "Impacts des usages du sol sur les propriétés physico-chimiques et le mercure du sol en Amazonie brésilienne : étude comparée du brûlis et de la trituration des jachères forestières." Mémoire, 2008. http://www.archipel.uqam.ca/1838/1/M10721.pdf.
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