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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Coordination chemistry in liquid ammonia and phosphorous donor solvents /

Nilsson, Kersti B., January 2005 (has links) (PDF)
Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniversitet, 2005. / Härtill 6 uppsatser.
2

Produtividade e eficiência biológica de Agaricus blazei (Murril) Heinnemann, em diferentes condições de cultivo

Kopytowski Filho, João [UNESP] 05 June 2006 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:31:33Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-06-05Bitstream added on 2014-06-13T21:02:46Z : No. of bitstreams: 1 kopytowskifilho_j_dr_botfca.pdf: 937520 bytes, checksum: bde78fc1e3f141927ac7ed3d0c134a81 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Universidade Estadual Paulista (UNESP) / A. blazei tem sido comercializado como um produto natural, sem aplicação de agrotóxicos e livre de resíduos tóxicos. De outro modo, elevados teores de elementos metálicos com potencial tóxico tem sido detectados em basidiomas. Outrossim, além da possibilidade de causarem danos á saúde, acarretam grandes prejuízos na comercialização. Avaliou-se o efeito de três tipos de compostos (orgânico, e semi-sintético and sintético) sobre a produtividade e teores de elementos metálicos em basidiomas de A. blazei. O Experimento 1 conduzido em câmara climatizada, constou de seis tratamentos (15 repetições), dispostos inteiramento ao acaso, em esquema fatorial 3x2, (três tipos de composto e duas linhagens de A. blazei). Avaliou-se a produtividade, a eficiência biológica, o massa média de basidiomas, os teores de Cd, Cr, Hg, Pb e Ni nos compostos e basidiomas e, o fator de acumulação no píleo e no estípete, em dois fluxos de colheita. Durante o processo de compostagem e de colonização, determinou-se o massa fresca e seca, teor de carbono, nitrogênio, pH densidade e umidade dos compostos. Constatou-se que os teores de elementos metálicos nos basidiomas não são proporcionais aos teores dos mesmos nos compostos cultivados, ocorre uma maior concentração destes no píleo em relação ao estípete e há variação em função do fluxo de colheita, a densidade e a umidade dos compostos ao final das Fases II e III, foram maiores nos compostos sintético e semi-sintético e as maiores produtividades de 7,24 e 7,09% para as linhagens ABL 99/30 e ABL 04/49, respectivamente, foram alcançadas quando cultivadas no composto orgânico certificado. Para o Experimento 2, 2 foram avaliados a produtividade e a massa média de basidiomas da linhagem... / A. blazei has been commercialized as a natural product, without use of pesticides and free from toxic waste. However, high contents of potencially toxic metallic elements in the basidiomata have usually been detected. Besides the health hazzard, they may cause great loss for comercialization. The effect of three different types of compost was evaluated (organic, semi-synthetic and synthetic) on the productivity and metallic elements contents in basidiomatas of A. blazei. The Experiment 1 was carried out in a climatized room, with six treatments (15 repetitions), arranged in a factorial scheme 3x2, (three differents types of compost and two strains of A. blazei). Productivity, biological efficiency, mean weight of basidiomatas, Cd, Cr, Hg, Pb and Ni contents in the compost and basidiomata and the accumulation factor in the pilei and stalk, in two flushes were evaluated. During composting and colonization, fresh and dry weight, carbon and nitrogen contents, pH ,density and moisture of the compost were evaluated. No direct relationship between the metallic elements contents in the mushroom and in the compost was found. The concentration of metallic elements was greater in the pileus then in the stalk, varying during the flushes. Density and moisture of the compost Phase II and III, were greater in the synthetic and semi-synthetic composts. The greatest productivities, 7.24 and 7.09% for the strains ABL 99/30 and ABL 04/49, respectively, were reached when cultivated in organic compost. For the Experiment 2, productivity and medium weight of the basidiomatas of the strain ABL 04/44, cultivated in synthetic compost added or not with two diffrents types of supplement (soybean meal and Champ food®), in two cultivation phases (at spawning and before casing) were evaluated. There was a tendency for greater productivity on the supplemented compost ... (Complete abstract, click electronic access below)
3

Desenvolvimento de métodos alternativos para a determinação dos íons metálicos sódio, potássio, cálcio e magnésio em amostras de biodiesel / Development of alternative methods for the determination of sodium, potassium, calcium and magnesium ions in samples of biodiesel

Caland, Lilia Basilio de, 1982- 19 August 2018 (has links)
Orientador: Matthieu Tubino / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-19T12:43:39Z (GMT). No. of bitstreams: 1 Caland_LiliaBasiliode_D.pdf: 2271472 bytes, checksum: b5d42f422be0f6983fc7ae4d28db0182 (MD5) Previous issue date: 2011 / Resumo: O trabalho reportou dois métodos alternativos para determinação de íons metálicos (Na, K, Ca e Mg) em amostras de biodiesel. Tais métodos foram aplicados em amostras de biodiesel sintetisados a partir de diferentes óleos vegetais e, também, de gordura animal. Os métodos propostos utilizam, no tratamento da amostra, extração líquido-líquido em meio aquoso ácido, com aquecimento e extração assistida por ultrassom. A quantificação dos íons metálicos é feita por cromatografia de íons (Na, K, Ca e Mg) e por fotometria de chama (Na, K). Uma melhor separação cromatográfica dos íons Na, K, Ca e Mg foi obtida quando se empregou como eluente uma solução mista de ácido dipicolínico 1,7 mmol L com HNO3 2,5 mmol L. Para o método empregando cromatografia de íons, os limites de detecção (LD) e os limites de quantificação (LQ) foram respectivamente: 0,28 e 0,83 mg kg (Na); 0,38 e 1,13 mg kg (K); 0,41 e 1,22 mg kg (Ca); 0,29 e 0,86 mg kg (Mg). Os desvios padrão relativos dos valores encontrados foram menores do que 18,6 %. A exatidão do método foi avaliada através de teste de recuperação, com resultados entre 88,45 e 109,8 %, e por comparação dos dados obtidos por ICP OES. O teste t-Student e o teste¿F mostraram que ambos os métodos apresentaram resultados equivalentes em termos de exatidão e precisão. Na fotometria de chama, os valores de LD e LQ, foram respectivamente: 0,6 e 1,8 mg kg (Na); 0,4 e 1,4 mg kg (K). A recuperação obtida foi de 92,1 % para Na e de 103,6 % para K. Na comparação dos teores dos íons Na e K fornecidos pelo procedimento que usa fotometria de chama com aqueles provindos da cromatografia de íons, não foi observada diferença significativa entre os resultados, ao nível de confiança de 95%, tanto no que se refere à exatidão como à precisão. A simplicidade, exatidão, precisão e custo relativamente baixo dos métodos propostos sugerem que podem ser boas alternativas para a determinação dos íons metálicos (Na, K, Mg e Ca) em amostras de biodiesel / Abstract: In this work reports two alternative methods for the quantitation of metallic ions (Na, K, Mg e Ca) in biodiesel samples. The proposed methods were applied to biodiesel that were synthesized from different vegetable oils and also animal fat. The proposed method uses water extraction, heating and ultrasound. The quantitation of the ions was performed using ion chromatography (Na, K, Mg e Ca) and flame photometry (Na, K).The best chromatographic separation of the cations (Na, K, Ca e Mg) was observed when a solution containing dipicolinic acid (1.7 mmol L) plus nitric acid was used (2.5 mmol L). For the method with ion chromatography, the limits of detection (LOD) and of quantitation (LOQ) were respectively: 0.28 and 0.83 mg kg (Na); 0.38 and 1.13 mg kg (K); 0.41 and 1.22 mg kg (Ca); 0.29 and 0.86 mg kg (Mg). The relative standard deviations of the obtained values were smaller than 18.6 %. The accuracy was determined through recovery procedures, with presented results between 88.45 and 109.8 %, and also by comparison with the data obtained from ICP-OES. The Student.s t-test and the F-test showed that both methods presented equivalent results in with respect to accuracy and precision. In the case of flame photometry the LD and LQ values were respectively: 0.6 and 1.8 mg kg (Na); 0.4 and 1.4 mg kg (K). The observed recoveries were 92.1 % for Na and 103.6 % for K. In the comparison between the set containing the results obtained for Na and K with flame photometry with that came from ion chromatography, it was not observed significant difference at the 95% confidence level, both with respect to accuracy as well to precision. The simplicity, accuracy, precision and relative low cost of the proposed methods suggest that they are interesting alternatives for the quantitation of metallic ions (Na, K, Mg and Ca) in biodiesel samples / Doutorado / Quimica Analitica / Doutor em Ciências
4

Evaluation des composants organiques d'un sol de cokerie en contexte d'atténuation naturelle / Evolution of coking plant soil components in a natural attenuation context

Biache, Coralie 01 July 2010 (has links)
Les sols de cokerie sont très hétérogènes, composés de matériaux de construction et de diverses phases organiques telles que du coke, du charbon, du goudron de houille et du bitume routier, jouant un rôle majeur sur les propriétés de ces sols. Leur nature et leur état de dégradation vont influencer la mobilité des différents contaminants. Cette thèse porte sur l’étude du vieillissement d’un sol de cokerie et ses conséquences sur le devenir des polluants organiques et métalliques. Elle intègre des études réalisées à différentes échelles permettant de considérer différents degrés de complexité, par l’utilisation (i) de composés purs, de matériaux organiques isolés (charbon, goudron de houille)et de sols et (ii) de dispositifs intégrant progressivement les différents processus intervenant lors de l’atténuation naturelle : expériences d’oxydation et de biodégradation en laboratoire, dispositif simplifié permettant de suivre l’évolution naturelle de quelques grammes d’échantillon, parcelles lysimétriques du GISFI permettant un suivi à l’échelle du terrain. Deux schémas de dégradation ont été identifiés au cours des expériences en laboratoire : (i) l’oxydation conduit à un phénomène de condensation qui suggère une stabilisation du compartiment organique ; (ii) la biodégradation induit la formation de plus petites unités moléculaires et la libération de composés organiques présents dans la fraction organique insoluble. Si des tendances sont identifiées au cours des expériences d’atténuation naturelle, elles suggèrent plutôt que le processus majeur impliqué est la biodégradation. La sorption du cuivre est variable selon les constituants organiques considérés, et augmente significativement après les expériences d’altération / Coking plant soils are highly heterogeneous and are made of building materials and various organic constituents such as coke, coal, coal –tar and road asphalt. Those materials can strongly influence soil properties. Thus, the retention of the various contaminants will depend on the nature and the degradation of the soil organic constituents. This work deals with the ageing of a coking plant soil and its consequences on the fate of both organic and metallic pollutants. The multi-scale approach applied in this study allows to consider the different levels of complexity through the use of (i) pure compounds, isolated organic fraction of soils such as coal tar and coal and a soil with its mineral fraction, and (ii) experimental devices gradually integrating the processes involved in natural attenuation : laboratory oxidation and biodegradation experiments, simplified device allowing the study of few grams of samples exposed to natural attenuation, and the GISFI (French Scientific Interest Group – Industrial Wasteland) lysimeter plots allowing the study at field scale). Two major evolutions were evidenced: (i) the oxidation led to a condensation suggesting a stabilization process of the organic compartment; (ii) the biodegradation induce the formation of smaller molecular units and the release of organic compounds from the non extractable part of the organic matter. The trends identified during the natural attenuation experiments suggest that the biodegradation is the major process involved in our ageing experiments. The sorption of copper varied according to the different organic constituents that were tested but was clearly enhanced by the degradation of these constituents
5

Metals in urban playground soils : distribution and bioaccessibility /

Ljung, Karin, January 2006 (has links) (PDF)
Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2006. / Härtill 4 uppsatser.
6

Ageing landfills : development and processes /

Östman, Monica, January 2008 (has links) (PDF)
Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2008. / Härtill 4 uppsatser.
7

Produtividade e eficiência biológica de Agaricus blazei (Murril) Heinnemann, em diferentes condições de cultivo /

Kopytowski Filho, João, 1971- January 2006 (has links)
Orientador: Marli Teixeira de Almeida Minhoni / Banca: Fernando Broetto / Banca: José Soares do Nascimento / Banca: Mario Barreto Figueiredo / Banca: Vera Lucia Ramos Bononi / Resumo: A. blazei tem sido comercializado como um produto natural, sem aplicação de agrotóxicos e livre de resíduos tóxicos. De outro modo, elevados teores de elementos metálicos com potencial tóxico tem sido detectados em basidiomas. Outrossim, além da possibilidade de causarem danos á saúde, acarretam grandes prejuízos na comercialização. Avaliou-se o efeito de três tipos de compostos (orgânico, e semi-sintético and sintético) sobre a produtividade e teores de elementos metálicos em basidiomas de A. blazei. O Experimento 1 conduzido em câmara climatizada, constou de seis tratamentos (15 repetições), dispostos inteiramento ao acaso, em esquema fatorial 3x2, (três tipos de composto e duas linhagens de A. blazei). Avaliou-se a produtividade, a eficiência biológica, o massa média de basidiomas, os teores de Cd, Cr, Hg, Pb e Ni nos compostos e basidiomas e, o fator de acumulação no píleo e no estípete, em dois fluxos de colheita. Durante o processo de compostagem e de colonização, determinou-se o massa fresca e seca, teor de carbono, nitrogênio, pH densidade e umidade dos compostos. Constatou-se que os teores de elementos metálicos nos basidiomas não são proporcionais aos teores dos mesmos nos compostos cultivados, ocorre uma maior concentração destes no píleo em relação ao estípete e há variação em função do fluxo de colheita, a densidade e a umidade dos compostos ao final das Fases II e III, foram maiores nos compostos sintético e semi-sintético e as maiores produtividades de 7,24 e 7,09% para as linhagens ABL 99/30 e ABL 04/49, respectivamente, foram alcançadas quando cultivadas no composto orgânico certificado. Para o Experimento 2, 2 foram avaliados a produtividade e a massa média de basidiomas da linhagem... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: A. blazei has been commercialized as a natural product, without use of pesticides and free from toxic waste. However, high contents of potencially toxic metallic elements in the basidiomata have usually been detected. Besides the health hazzard, they may cause great loss for comercialization. The effect of three different types of compost was evaluated (organic, semi-synthetic and synthetic) on the productivity and metallic elements contents in basidiomatas of A. blazei. The Experiment 1 was carried out in a climatized room, with six treatments (15 repetitions), arranged in a factorial scheme 3x2, (three differents types of compost and two strains of A. blazei). Productivity, biological efficiency, mean weight of basidiomatas, Cd, Cr, Hg, Pb and Ni contents in the compost and basidiomata and the accumulation factor in the pilei and stalk, in two flushes were evaluated. During composting and colonization, fresh and dry weight, carbon and nitrogen contents, pH ,density and moisture of the compost were evaluated. No direct relationship between the metallic elements contents in the mushroom and in the compost was found. The concentration of metallic elements was greater in the pileus then in the stalk, varying during the flushes. Density and moisture of the compost Phase II and III, were greater in the synthetic and semi-synthetic composts. The greatest productivities, 7.24 and 7.09% for the strains ABL 99/30 and ABL 04/49, respectively, were reached when cultivated in organic compost. For the Experiment 2, productivity and medium weight of the basidiomatas of the strain ABL 04/44, cultivated in synthetic compost added or not with two diffrents types of supplement (soybean meal and Champ food®), in two cultivation phases (at spawning and before casing) were evaluated. There was a tendency for greater productivity on the supplemented compost ... (Complete abstract, click electronic access below) / Doutor
8

From wood to waste and waste to wood : aspects on recycling waste products from the pulp mill to the forest soil /

Rothpfeffer, Caroline, January 2007 (has links) (PDF)
Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2007. / Härtill 4 uppsatser.
9

Transfert des éléments traces métalliques vers les végétaux : mécanismes et évaluations des risques dans des environnements exposés à des activités anthropiques / Transfer of metallic elements to plants : mecanisms and risk assessments in environments exposed to anthropogenic activities

Assad, Mohamad 16 February 2017 (has links)
Les décharges de résidus riches en éléments traces métalliques (ETMs) issus des activités industrielles représentent un risque potentiel de pollution de l’environnement. Ces décharges de résidus exigent une stabilisation des ETMs pour limiter leur dispersion par l'air, le sol, et les cours d’eau, et in fine leur transport vers des zones initialement non contaminées. Cette stabilisation peut être obtenue par un couvert végétal adéquat. Ce travail de thèse a porté sur 3 sites expérimentaux, qui ont comme point commun d’être des zones de stockage de sédiments contaminés ou d’effluents industriels chargés en ETMs. L’objectif général de ce travail de thèse était d’étudier les modes de transfert et de stockage d’ETMs vers les parties aériennes de végétaux cultivés sur les sols issus de ces sites expérimentaux. Le premier objectif concernait une décharge d’effluents (Inovyn), issus de l’activité électrolytique de l’usine Solvay (Tavaux) et enrichi en Hg. Le Hg, en raison de son faible point d’ébullition est facilement transféré des sédiments vers l’atmosphère sous forme de composés volatiles. Ainsi, la couverture végétale de cette lagune est exposée par sa biomasse aérienne aux composés volatiles de Hg, mais également par la rhizosphère aux composés du Hg présents dans le substrat. Dans ce travail de thèse plusieurs espèces végétales de la famille des Salicacées (peuplier) et des Solanacées (poivron, tomate, aubergine, et tabac) ont été exposées au Hg, dans des expériences en pot, avec simple exposition à une atmosphère enrichie en Hg, ou double exposition à un sol et à une atmosphère enrichis en Hg. Dans tous les cas de figure, le transfert de Hg dans les feuilles ne se produit que par voie aérienne, et l’accumulation augmente significativement avec l’âge des feuilles. Nous avons également mis en évidence que les teneurs en Hg des fruits des Solanacées étaient environ 100 fois plus faibles que celles des feuilles, limitant ainsi le risque d’exposition au Hg par leur consommation. Nous avons par ailleurs démontré qu’une faible proportion (7%) du Hg est sous forme méthylHg dans les feuilles de peuplier, et que 16 à 26% du Hg accumulé dans les feuilles de poivron ou peuplier étaient liés à des protéines solubles. Le deuxième objectif concerne les sites de Thann (Cristal) et Fresnes sur Escaut (VNF), pour lesquels nous avons étudiés le transfert d’ETMs vers des espèces potagères, afin de mimer l’impact de ces contaminants sur les cultures en jardins potagers. Le peuplier a également été utilisé comme espèce de référence. Les quantités de masse fraîche des parties comestibles à ingérer pour atteindre la dose journalière ont été calculées pour chaque ETM. Seuls le Cd (Fresnes) et le Cr (Thann) présentaient un risque potentiel, puisqu’ils s’accumulent dans les parties consommables de ces végétaux à des teneurs élevées. Il faut toutefois noter que ces expériences ont été réalisées dans des scénarios où les conditions d’exposition étaient maximisées. Le transfert des ETMs (notamment le Cd et le Zn) vers le peuplier a confirmé des études précédentes, ce qui souligne l’importance d’une gestion adaptée de la biomasse produite sur de tels sites. D’un point de vue écologique les travaux de cette thèse confirment l’importance et la nécessité de la végétalisation des sites contaminés par des ETMs afin de limiter la dispersion des poussières, et en conséquence les ETMs aux alentours. D’un point de vue sanitaire, les travaux soulignent l’importance d’estimer le risque spécifique lié à l’ingestion d’espèces végétales d’intérêt alimentaires cultivées régulièrement par les habitants aux alentours des sites potentiellement émetteurs d’ETMs, en générant un lien entre espèce et ETMs accumulés. Ce travail apporte donc un certain nombre d’éléments pour la compréhension du devenir d’ETMs et notamment le Hg dans le système sol/plante et les risques associés à l’ingestion des parties comestibles des végétaux cultivés potentiellement contaminées. / Metal trace element (HME) -free residues from industrial activities represent a potential risk of environmental pollution. These tailings dumps require a stabilization of the ETMs to limit their dispersion by air, soil, and streams, and ultimately their transport to initially uncontaminated areas. This stabilization can be achieved by adequate plant cover. This thesis work focused on 3 experimental sites, which have as common point to be contaminated sediment storage areas or industrial effluents loaded with ETMs. The general objective of this thesis work was to study the transfer and storage modes of ETMs to the aerial parts of plants grown on soils from these experimental sites. The first objective concerned a discharge of effluents (Inovyn), resulting from the electrolytic activity of the Solvay (Tavaux) plant and enriched in Hg. The Hg, because of its low boiling point, is easily transferred from the sediments to the atmosphere in the form of volatile compounds. Thus, the vegetal cover of this lagoon is exposed by its aerial biomass to the volatile compounds of Hg, but also by the rhizosphere to the Hg compounds present in the substrate. In this work, several plant species of the Salicaceae family (poplar) and Solanaceae (pepper, tomato, aubergine, and tobacco) were exposed to Hg in pot experiments, with simple exposure to a Hg-enriched atmosphere. , or double exposure to Hg-enriched soil and atmosphere. In all cases, transfer of Hg into the leaves occurs only by air, and accumulation increases significantly with leaf age. We also found that the Hg content of the Solanaceae fruit was about 100 times lower than that of the leaves, thus limiting the risk of exposure to Hg through their consumption. We have also shown that a small proportion (7%) of the Hg is in the form of methylHg in poplar leaves, and that 16 to 26% of the Hg accumulated in pepper or poplar leaves were bound to soluble proteins. The second objective concerns the Thann (Cristal) and Fresnes sur Escaut (VNF) sites, for which we have studied the transfer of ETMs to vegetable species, in order to mimic the impact of these contaminants on vegetable garden crops. Poplar has also been used as a reference species. The amounts of fresh mass of the edible parts to be ingested to reach the daily dose were calculated for each MTE. Only Cd (Fresnes) and Cr (Thann) presented a potential risk, since they accumulate in the consumable parts of these plants at high levels. It should be noted, however, that these experiments were conducted in scenarios where exposure conditions were maximized. The transfer of ETMs (including Cd and Zn) to poplar has confirmed previous studies, highlighting the importance of appropriate management of the biomass produced at such sites. From an ecological point of view, the work of this thesis confirms the importance and the necessity of the revegetation of the sites contaminated by ETMs in order to limit the dispersion of the dust, and consequently the ETMs around. From a health point of view, the work emphasizes the importance of estimating the specific risk related to the ingestion of vegetable species of interest regularly grown by the inhabitants around the sites potentially emitting ETMs, generating a link between species and accumulated ETMs. This work therefore provides a number of elements for understanding the fate of ETMs and in particular the Hg in the soil / plant system and the risks associated with the ingestion of the edible parts of potentially contaminated cultivated plants.
10

Dynamique des flux sédimentaires et des éléments métalliques en lien avec l’exploitation courante et exceptionnelle d’un barrage hydroélectrique / Influence of routine and exceptional exploitation of a hydroelectric dam on sediments and metallic elements dynamics

Frémion, Franck 29 November 2016 (has links)
Les retenues de barrage sont l’objet d’enjeux sociétaux, économiques et environnementaux. Leur présence affecte le transit naturel de l’eau et de la charge sédimentaire associée. Selon les cycles hydrologiques et leur exploitation, la remobilisation des sédiments accumulés et des contaminants associés est plus ou moins marquée. Dans ce contexte, cette étude a pour principal objectif de déterminer l’évolution des teneurs, flux et spéciation des éléments métalliques au cours des phases d’accumulation et de remobilisation sédimentaire naturelles et influencées. Pour ce faire, une étude de terrain de 19 mois à l’amont et à l’aval de l’ouvrage a été effectuée en conditions courantes et événementielles d’exploitation. Le suivi de deux opérations de chasses d’hydrocurage, destinées à l’évacuation des sédiments de la retenue par ouverture des vannes de fond du barrage en période de hautes eaux, a notamment été réalisé. L’impact des différents paramètres physicochimiques (ratio solide/liquide, pH, potentiel redox, séchage) sur le devenir et la spéciation des éléments métalliques ainsi que les différents mécanismes associés ont quant à eux été évalués à l’aide d’expériences de laboratoire, d’études statistiques et de modélisation. Les résultats ont montré qu’en période d’exploitation courante, la présence de l’ouvrage induit une discontinuité amont/aval des teneurs, flux et partition des éléments métalliques, amplifiant notamment l’influence du pH sur leur spéciation et mobilité du fait de l’artificialisation des conditions d’écoulement. Lors des opérations d’exploitation événementielle par chasse d’hydrocurage, la modification des conditions de pH, d’oxydoréduction et de ratio S/L au sein du cours d’eau aval lors du passage de la charge sédimentaire augmente les teneurs en As, Fe et Mn solubilisés via des phénomènes de désorption et de dissolution des oxydes métalliques. Néanmoins, étant donné la faible mobilité des éléments métalliques et la stabilité des phases porteuses, les flux dissous restent minoritaires par rapport aux flux particulaires. La réalisation fréquente des opérations de chasse permet de minimiser les flux sédimentaire et métallique mis en jeu au cours du temps, limitant par conséquent son impact sur le cours d’eau aval. / Dam reservoir contexts concentrate social, economic and environmental issues. Their presence modifies both natural water and sediments continuity. Water level can be stable or fluctuate according to hydrological cycles and exploitation, leading to more or less pronounced sediments and associated contaminants remobilization. In such context, this work aims at studying spatio-temporal changes in concentrations, fluxes as well as speciation of metallic elements during natural and anthropologically-driven sediments accumulation and resuspension phases. For this purpose, a 19 months field survey was performed upstream and downstream from the dam during both routine and exceptional exploitation. The water and sediments quality during two sluicing events, performed in order to re-erode deposited reservoir sediments and flush them downstream through the bottom valves of the dam during high flows, were notably monitored. As for the influence of the main physicochemical parameters (i.e., solid/liquid ratio, pH, redox potential, drying) on metallic elements fate and speciation as well as the different processes involved, they were studied through laboratory experiments, statistical analyses and modeling. Results highlighted that during routine exploitation, dam presence leads to a significant discontinuity in metallic element dissolved concentrations, fluxes and speciation, mainly through pH changes magnified by water flow artificial lowering. During sluicing management, the high local pH, redox and S/L changes of the downstream water, mainly following maximum sediments release, enhance As, Fe and Mn solubilization through desorption or metallic oxydes dissolution. Nevertheless, given the overall low mobility of the metallic elements and bearing phases stability, dissolved fluxes remain far lower than particular ones. Recurrent sluicing management permits to minimize sediments and metallic fluxes, limiting toxicity towards aquatic biota.

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