Rozprawy doktorskie: „Bioaccumulation”

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Yu, Shuo. "Bioaccumulation of Metals in Earthworms". The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1259697144.

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Al-Ansari, Ahmed. "Bioaccumulation of 17α-Ethinylestradiol in Fish". Thesis, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/22684.

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The active synthetic constituent of oral contraceptives 17α- ethinylestradiol (EE2) and its natural steroidal estrogen analogues are being released into the aquatic environment mainly via wastewater treatment plants (WWTPs). Although steroidal estrogens have been frequently reported in very low concentrations in the environment, they have been placed at the top of the list of endocrine disrupting chemicals (EDCs) for their high estrogenic activity in non-target aquatic species like fish and frogs. Almost 30 years worth of intensive research has moved the problem of endocrine disruption in the aquatic environment from being a hypothesis to a well-known cause-and-effect story. However, the fate and effects of many pharmaceuticals, including EE2, remain poorly understood. Thus, the main objective of this thesis was to investigate EE2 bioaccumulation in fish by field and laboratory studies. An optimized sample preparation and analytical method protocol was achieved to detect EE2 in its biologically active form in whole fish tissue at trace levels (ng/g). Shorthead redhorse suckers (ShRHS) (Moxostoma macrolepidotum) collected in proximity to a WWTP in the St. Clair River have significantly accumulated EE2 with an average of 1.5 ng/g. EE2 bioaccumulation was limited to fish exhibiting intersex and with induced vitellogenin (VTG). EE2 was absent in fish from a reference site. Positive correlations between EE2 and lipid content as well as "15N supported the hypothesis of EE2 bioaccumulation in wild ShRHSs. A wider survey was carried out to explore patterns of EE2 bioaccumulation in the pelagic and benthic food-wed of the St. Clair IV River, Ontario. In the WWTP effluents and nearby surface waters, EE2 levels were extremely low and below our method detection limits. All of the seven sampled species from different trophic levels and the sediment samples collected from the impacted sites and the reference sites did not have any measurable EE2 concentrations. A laboratory controlled study where male goldfish (Carassius auratus) were exposed to EE2 via water versus food demonstrated that fish can rapidly accumulate EE2 by both routes of exposure. The uptake constant for water was 45 h-1 and the bioconcentration factor for EE2 in fish was 377. The fast uptake rate of EE2 via water coincided with a much slower elimination rate constant of 0.0786 h-1. The assimilation efficiency of 0.106 for EE2 by goldfish was determined by EE2 dietary exposure, which was used to predict EE2 accumulation under different exposure scenarios. The work presented here was the first demonstration of EE2 bioaccumulation in wild fish and the first to model EE2 bioaccumulation from water and dietary exposure in laboratory-exposed fish.

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Strady, Emilie. "Mécanismes biogéochimiques de la contamination des huîtres Crassostrea gigas en Cadmium en baie de Marennes Oléron". Thesis, Bordeaux 1, 2010. http://www.theses.fr/2010BOR14060/document.

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La baie de Marennes Oléron, premier site ostréicole français, est influencée par la pollution polymétallique historique de l’estuaire de la Gironde avec des concentrations en cadmium dans les huîtres proches de la limite de consommation européenne (RNO 2006; 5 μg.g-1 ps, ECNo.466/2001). Ces travaux de recherche pluridisciplinaires ont pour objectif de caractériser le comportement des ETM en zone côtière et les mécanismes de contamination en ETM des huîtres, spécifiquement en Cd, dans la baie de Marennes Oléron. Pour cela, sept missions océanographiques en période contrastée ont permis de caractériser la spéciation des ETM à l’embouchure des estuaires de la Charente et de la Gironde ainsi qu’au Pertuis de Maumusson.Une étude spatio-temporelle complémentaire des sédiments de surface de la baie de Marennes Oléron a montré un enrichissement des sédiments de surface en Cd dans la zone sud baie,confirmant la connexion des eaux girondines et l’apport en Cd particulaire à la baie par le Pertuis de Maumusson. Cette zone sud a ainsi été choisie pour mener une transplantation d’huîtres pendant trois mois. L’hydrodynamique régionale, observée par imagerie satellite, a présenté unrôle important dans la distribution et la variation temporelle des concentrations en Cd dissous et particulaires minérales de la baie. La bioaccumulation en Cd des différents organes d’huîtres cultivées sur table a été plus importante que celle des huîtres cultivées directement sur le sol,suggérant le faible rôle de la diffusion de Cd par la remise en suspension des sédiments de surface et du microphytobenthos sur la bioaccumulation. De plus, le temps d’immersion étant relativement proche entre les deux conditions, nous suggérons que la voie trophique via le plankton pélagique participe à la contamination des huîtres en plus de la voie directe. Cette contribution de la voie trophique a été confirmée lors d’expérimentations en conditions contrôlées en laboratoire par le développement d’une méthode de traçage simultané des voies de contamination directe et trophique par ajouts d’isotopes stables de Cd, conduites pour des concentrations 10 fois supérieures à l’environnement et des concentrations réalistes observées en baie de Marennes Oléron (40 ng.l-1 et ~0.7 mg.kg-1)
The Marennes-Oléron Bay, hosting the largest oyster production in France, is influenced by thehistoric polymetallic pollution of the Gironde Estuary, with cadmium levels in oysters close tothe consumption limit level (5 μg.g-1 dw, EC No.466/2001). The aim of this pluridisciplinarywork was to characterize the behaviour of trace metals in the coastal zone and the mechanisms ofCd contamination in oysters in the Marennes Oléron Bay. Seven oceanographic cruises wereconducted during contrasting season to characterize trace metals behaviour and speciation in theGironde and Charente estuaries and the coastal zone. Then, a spatial and temporal study of tracemetals in the surface sediments of the Marennes-Oléron Bay showed punctual Cd-enrichedsediments in the southern part, reflecting the connexion with the Gironde waters and theparticulate Cd inputs via the Maumusson inlet. Thus, this area was chosen to study Cdbioaccumulation in oysters over a three months transplantation. The regional hydrodynamic,observed by satellite images, played an important role on Cd speciation and the temporalvariability of dissolved and particulate Cd concentrations. Cadmium bioaccumulation in organsof oysters reared on tables at 60 cm height was more important than in oysters reared near thesediment, suggesting the absence of Cd released during tidal suspension from sediment andmicrophytobenthos. Furthermore, as the immersion time was closed between the two rearingconditions, we suggested Cd bioaccumulation via the direct pathway and also via trophicpathway of contamination by pelagic plankton ingestion. This trophic pathway of Cdcontamination was validated during laboratory experiments using a simultaneous tracing of Cddirect and trophic pathways in oysters by stable isotope spikes at concencentrations 10-foldhigher than the Gironde Estuary and at realistic concentrations observed in the Marennes-OléronBay

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Kuhn, Sabine Plocher. "Bioaccumulation of metals using immobilized Zoogloea ramigera /". The Ohio State University, 1988. http://rave.ohiolink.edu/etdc/view?acc_num=osu148759497065045.

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HEGE, SYLVIA. "Bioaccumulation de metaux chez des champignons macromycetes". Strasbourg 1, 1989. http://www.theses.fr/1989STR15019.

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Rodrigues, Sandra. "Mercury bioaccumulation in the Egyptian mongoose (Herpestes ichneumon)". Master's thesis, Universidade de Aveiro, 2012. http://hdl.handle.net/10773/10685.

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Mestrado em Química Analítica e Qualidade
O sacarrabos (Herpestes ichneumon) é um predador que desempenha um papel essencial na cadeia alimentar terrestre. A sua introdução e rápida proliferação pelo território português levaram à necessidade da sua caça como controlo de predadores. Estudos em espécies predadoras terrestres ainda são escassos, pelo que o presente trabalho representa uma mais-valia para um melhor entendimento da acumulação de contaminantes em níveis tróficos superiores. Existem vários contaminantes que representam uma constante preocupação para o ambiente; entre eles, o mercúrio tem tido uma atenção acrescida devido à sua persistência e toxicidade. Estudos no meio terrestre são importantes para um melhor entendimento da forma como se acumula neste meio, para a preservação da vida selvagem mas também para prevenir a exposição humana ao mercúrio. Este estudo teve como principal objectivo avaliar os padrões de acumulação de mercúrio nos tecidos do H. ichneumon, tendo em atenção factores como o género e a idade. H. ichneumon de localizações diferentes foram analisados de forma a avaliar a variação geográfica dos níveis de mercúrio em território Português. Músculo, fígado, pulmão, coração, baço, rins, sangue, cérebro, gordura e pêlo de 29 indivíduos provenientes de 14 localizações foram analisados (Évora, Soure, Ferreira do Zêzere, Castelo Branco, Mértola, Torres Novas, Tondela, Lousã, Coimbra, Montemor-o-Novo, Castro Daire, Olhão, Moura e Coruche). Além disso, de forma a estudar diferenças entre machos e fêmeas ao longo do ciclo de vida da espécie, 25 indivíduos provenientes de Serpa foram analisados. Os níveis de mercúrio nos diferentes órgãos variaram entre 0.01 e 12.7 μg g-1 peso seco, e seguiram geralmente a seguinte ordem, do menos para o mais contaminado: Gordura 0.74). Verificou-se que os níveis de mercúrio no sangue e no fígado estão fortemente correlacionados (r=0.998). O mercúrio orgânico presente no tecido muscular dos machos e das fêmeas foi analisado e a sua percentagem variou entre 77 e 98%. A correlação entre mercúrio orgânico e total nos machos foi de 1.000 e de 0.986 nas fêmeas. Nenhum dos níveis de mercúrio atingiu valores considerados letais ou tóxicos para predadores terrestres (20 a 100 μg g-1 peso seco).
The Egyptian mongoose (Herpestes ichneumon), a terrestrial predatory species, has an essential role in the terrestrial food chain. Their introduction in Portugal and rapid proliferation throughout Portuguese territory led to the necessity of their hunt as predator control measure. Studies in terrestrial predatory species are sparse; thereby, the present study is an asset for a better understanding of contaminants accumulation in higher trophic levels. Many contaminants are of environmental concern; mercury has had increased attention due to its persistence and toxicity. Studies have been mostly directed to aquatic wildlife due to the fact that fish consumption is considered to be the principal route of human exposure to mercury. However, terrestrial wildlife studies are also important for a better understanding of mercury accumulation, wildlife preservation and also for preventing human exposure to mercury. The main purpose of this study was to evaluate the different tissue accumulation in H. ichneumon, as well as differences between males and females, throughout the lifespan of the species. H. ichneumons from different locations were also analyzed in order to compare levels throughout Portuguese territory. Muscle, liver, lungs, heart, spleen, kidneys, blood, brain, fat and pelage were analyzed for 29 H. ichneumon from 14 locations (Évora, Soure, Ferreira do Zêzere, Castelo Branco, Mértola, Torres Novas, Tondela, Lousã, Coimbra, Montemor-o-Novo, Castro Daire, Olhão, Moura and Coruche). In order to study differences between ages, males and females, 25 individuals from Serpa were analyzed. Total mercury concentrations in H. ichneumon tissue samples ranged between 0.01 to 12.7 μg g-1 dw, and followed the order, from least to most contaminated: Fat 0.74), not visible in females. Moreover, correlations between organs showed that blood and liver were highly correlated (r=0.999). Organic mercury in muscle tissue of males and females was analyzed and its percentage ranged from 77% to 98%. Correlation between organic and total mercury in males was 1.000 and 0.995 for females. None of the mercury levels reached the lethal or toxic values established for terrestrial predators (20 to 100 μg g-1 ww).

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Rodrigues, Andreia do Carmo Martins. "Mercury toxicity and bioaccumulation: lab & field studies". Master's thesis, Universidade de Aveiro, 2011. http://hdl.handle.net/10773/7457.

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Mestrado em Biologia Aplicada - Toxicologia e Ecotoxicologia
This work aims to evaluate the toxicity, bioaccumulation and biomagnification of mercury and it is divided into a laboratory and a field component. The laboratory component was divided into two parts and the field component was conducted into an estuarine environment in Ria de Aveiro, Portugal. In the laboratory we started by evaluating the toxicity of mercury for different aquatic organisms, using mercury concentrations that ranged between 0.5 μg/L to 2.4 mg/L. The chosen species used in this assay to evaluate mercury toxicity were the models: Pseudokirchneriella subcapitata, Daphnia magna and Chironomus riparius and the autochthonous species: Chlorella vulgaris, Lemna minor and Daphnia longispina. Mercury showed to be toxic to all testes species, with EC50 values ranging from 7.3 μg Hg/L (immobilization test of D. longispina) to 1.58 mg Hg/L (immobilization test of the larvae of C. riparius). The assay showed that even low doses of mercury can cause significant effects at the levels of primary producers, the base of the trophic chain. In the secondary laboratorial assay, an aquatic trophic chain was simulated using the primary producer P. subcapitata, the primary consumer D. magna and the secondary consumer Danio rerio. The trophic chain mercury contamination process was initiated exposing an algae culture to inorganic mercury (10 μg Hg/L), resulting in the accumulation of 70% of the available mercury in the primary producer. The contaminated algae were then used as food supply to the specie D. magna and subsequently D. magna specimens were used as food to the secondary consumer. After 14 days of exposure D. magna accumulates 0.14 μg Hg/g, whereas the final average concentration obtained in the muscle of the fish D. rerio after 21 days was 0.27 μg Hg/g (wet weight). All test species accumulate mercury along the time of exposure; the higher biomagnification occurred from the microalgae P. subcapitata to the mircrocrustacean D. magna, enhancing the crucial role of primary producers in the bioconcentration of mercury from the water column along the trophic chain. Fieldwork was conducted in the Ria de Aveiro, in two specific sites (Cais do Bico and Barra) that were already characterized regarding dissimilar environmental mercury contamination levels. Mercury levels were evaluated in the water column (total mercury), sediments (total and organic mercury) and in juvenile fish Liza aurata inhabiting the area (total and organic mercury). Cais do Bico site, located near the source of contamination showed the highest values of total mercury: 68 ng/L in the water column, 0.19 μg/g in the sediments and 0.07 μg/g in fish. The site distant from the source of mercury (Barra) presented a great amount of organic mercury in the sediments (0.02 μg/g) and a higher percentage of organic mercury in fish muscle (96%). The study indicates that, although mercury discharges have already stopped in the end of the last century, mercury stored in sediments continues to be ressuspended to the water column, becoming bioavailable to biota. The adoption of juvenile specimens provides information on short-term variations of mercury concentrations in the environment.
O objectivo deste trabalho é avaliar a toxicidade, a bioacumulação e a bioamplificação de mercúrio. O trabalho apresenta uma componente laboratorial e uma componente de campo. A componente laboratorial foi dividida em duas partes e a componente de campo foi realizada num ambiente estuarino, Ria de Aveiro, Portugal. Na componente laboratorial, começou por se avaliar a toxicidade do mercúrio para diferentes organismos aquáticos, testando-se concentrações de mercúrio entre 0,5 μg/L e 2,4 mg/L. As espécies teste escolhidas para avaliar a toxicidade do mercúrio incluíram espécies modelo: Pseudokirchneriella subcapitata, Daphnia magna e Chironomus riparius, e espécies autóctones: Chlorella vulgaris, Lemna minor e Daphnia longispina. O mercúrio revelou ser tóxico para todas as espécies, obtendo-se valores de EC50 que variaram de 7.3 μg Hg/L (teste de imobilização de D. longispina) a 1,58 mg Hg/L (teste de imobilização das larvas de C. riparius). Este ensaio demonstrou que pequenas doses de mercúrio provocam efeitos consideráveis ao nível dos produtores primários, base das cadeias tróficas. Num segundo procedimento experimental construiu-se uma cadeia trófica aquática, constituída pelo produtor primário P. subcapitata, pelo consumidor primário D. magna e o consumidor secundário Danio rerio. A contaminação iniciou-se pelo meio de cultura das algas com 10 μg Hg/L, do qual estas acumularam 70% do mercúrio disponível. Esta espécie foi usada como alimento para D. magna, que por sua vez, foi usada como alimento para o consumidor secundário Danio rerio. Após um período de 14 dias de teste D. magna acumulou 0,14 μg Hg/g. A concentração média obtida no músculo de D. rerio, após 21 dias de teste, foi de 0,27 μg Hg/g, peso fresco. Todos os organismos acumularam mercúrio ao longo do tempo de exposição, sendo que a maior bioamplificação de mercúrio ocorreu da microalga P. subcapitata para o microcrustáceo D. magna, reforçando assim o papel crucial dos produtores primários na bioconcentração de mercúrio da coluna de água para as cadeias tróficas. O trabalho de campo foi realizado na Ria de Aveiro, em dois sítios específicos, cuja caracterização em termos de contaminação por mercúrio já estava descrita. Estudou-se a carga de mercúrio total na coluna de água, bem como o mercúrio total e orgânico nos sedimentos e a sua transferência e acumulação para peixes juvenis residentes na área, Liza aurata. O Cais do Bico, local mais próximo da fonte de contaminação apresentou os maiores valores de mercúrio total: 68 ng/L na coluna de água, 0,19 μg/g nos sedimentos e 0,07 μg/g nos peixes. O local mais distante da fonte de mercúrio, Barra, apresentou uma maior quantidade de mercúrio orgânico nos sedimentos (0,02 μg/g) e uma percentagem de mercúrio orgânico no músculo dos peixes igualmente superior, de 96%. Esta monitorização comprovou que, embora as descargas industriais de mercúrio já tenham sido interrompidas no final do século passado, o mercúrio armazenado nos sedimentos continua a ser ressuspendido para a coluna de água, ficando biodisponível para a biota. A utilização de organismos juvenis fornece informações sobre as variações a curto prazo das concentrações de mercúrio no ambiente.

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Naigaga, Irene. "Bioaccumulation and histopathology of copper in Oreochromis mossambicus". Thesis, Rhodes University, 2003. http://hdl.handle.net/10962/d1005077.

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Cu is one of the most toxic elements that affect fish populations when the fish are exposed to concentrations exceeding their tolerance. To investigate the effects of elementary Cu on aspects of bioconcentration, histology and behaviour, O. mossambicus were exposed to 0 and 0.75 ± 0.20 mg/l of Cu for 96 hours (short-term study), and 0, 0.11 ± 0.02, 0.29 ± 0.02, and 0.47 ± 0.04 mg/l of Cu for 64 days (longterm study) under controlled conditions in the laboratory. For the long-term study fish were sampled for gills, liver, and kidney Cu accumulation analysis after 1, 32 and 64 days of exposure and after 1, 2, 4, 16, 32, and 64 days for gills, liver and spleen histology analysis. Cu accumulation was concentration-duration dependent with the highest accumulation capacity in the liver. A multifactor linear model was developed for the relationship between exposure dose, exposure duration and Cu accumulation in the organs with the liver model: Log L = 3.35 + 0.85W + 0.31T (r² = 0.892) giving a better fit than the gills: G = −35.09 + 10.58W + 17.58T (r² = 0.632). Where L = Cu accumulation values in the liver, G = Cu accumulation values in the gills (both in μg/g dry mass); W = exposure dose in water (mg/l); and T = exposure time (days). Using this model Cu accumulation in organs can be estimated when exposure concentration and duration is known. This model should be tested under different conditions to determine the potential of the model in monitoring Cu toxicity in the environment. Lesions were observed in the liver, gills and spleen in all Cu treatments at all exposure concentration and exposure durations. However, the incidence and the degree of alteration was related to the concentration of Cu and duration of exposure. The sequential appearance of lesions in the order of, hepatic vacuolar degeneration, fatty degeneration and necrosis indicated a gradual increase in liver damage with larger duration of exposure time and increasing Cu concentration. The initial lesions in the gills were manifested as hypertrophy and hyperplasia of the gill epithelium causing increase in the thickness of the secondary lamellae, mucous cell hypertrophy and proliferation, mucous hypersecretion, proliferation of eosinophilic granule cells and hyperplasia of interlamellar cells. With increase in exposure time, necrosis of the eosinophilic granule cells, lamellar oedema, epithelial desquamation and increase in severity of lamellar hyperplasia were observed. These lesions indicated an initial defence mechanism of the fish against Cu toxicity followed by advanced histological changes that were related to Cu concentration and duration of exposure. Changes in the spleen were haemosiderosis, increase in the white pulp and macrophage centres, reduction in the red pulp, and necrosis suggesting that fish exposed to environmentally relevant levels of Cu may be histopathologically altered leading to anaemia and immunosuppression. Regression analysis was used to quantify the relationship between the total activity of the fish, and duration of exposure. There was a gradual decline in fish activity related to Cu concentration and duration of exposure before introducing food into the tanks. There was a constant activity after introducing food in the tanks at the control and 0.11 ± 0.02 mg/l Cu exposure levels irrespective of exposure time. Analysis of covariance (ANCOVA) was used to test for the difference in slopes between treatments. There was no significant difference (p > 0.05) between slopes of the control and 0.11 ± 0.02 mg/l Cu, and between 0.29 ± 0.02 and 47 ± 0.04 mg/l Cu before and after introducing food in the tanks. The slopes of both the control and 0.11 ± 0.02 mg/l Cu were significantly different from those of 0.29 ± 0.02 and 0.47 ± 0.04 mg/l Cu (p < 0.05). There were significant differences in the mean opercular movements per minute between treatments (p < 0.05). There was hyperventilation at 0.11 ± 0.02 mg/l Cu i.e. 87 ± 18 opercular movements per minute (mean ± standard deviation) and hypoventilation at 0.29 ± 0.02 and 0.47 ± 0.04 mg/l Cu i.e. 37 ± 34 and 13 ± 6 opercular movements per minute compared to the control. Hypo- and hyperventilation were related to the lesser and greater gill damage, respectively. In conclusion Cu accumulation and effects on histology of the liver, gills and were related to the concentration of Cu in the water and duration of exposure showing a gradual increase in incidence and intensity with larger duration of exposure time and increasing Cu concentration. The fish were initially able to homeostatically regulate and detoxify Cu. However, as the exposure continued, the homeostatic mechanism appears to have failed to cope with the increasing metal burden causing advanced histological changes.

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Farmer, Troy Mason DeVries Dennis R. Wright Russell A. "Mercury bioaccumulation patterns in two estuarine sportfish populations". Auburn, Ala, 2008. http://hdl.handle.net/10415/1459.

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Giansiracusa, Sara. "Bioaccumulation of legacy and emerging contaminants in tuna species". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/18305/.

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Environmental contamination of legacy contaminants has been of great concern worldwide because of their persistence and toxicity to humans and marine species. Only in the last decade, the presence and accumulation of emerging contaminants, and, consequently, their adverse effects in marine biota have been considered. The present research was performed to compare the different distribution of legacy contaminants (Pesticides, PCBs and PAHs) and emerging contaminants (UV filters and Fragrances) in the liver and muscle tissues of three tuna species living in different locations and with different behaviour and feed habits: Sarda sarda, Katsuwonus pelamis from the Atlantic Ocean (Gulf of Càdiz) and Thunnus thynnus from the Strait of Gibraltar. The extraction and quantitative determination of these contaminants from liver and muscle samples have been carried out by Accelerate Solvent Extraction and GC-MS/MS techniques, respectively. From the statistical analysis, significant differences have been found for Fragrances, Pesticides, PCBs and PAHs both among the three tuna species and between the two tissues. Post-hoc analysis showed significant differences between the three tuna species and the tissues, revealing that K. pelamis species differs significantly from the other two species, both in liver and muscle, and that legacy contaminants are responsible for significant differences between and within species. We also explored the similarities between concentrations of PCBs and DDTs in liver and muscle tissue found in samples of T. thynnus and K. pelamis in this study, compared to concentrations of PCBs and DDTs found in specimens of tuna collected in different geographical areas. As a result of the continuous exposure of the marine top predators, such as tuna species, to variable concentrations of emerging and legacy contaminants, their concentration in the marine environment must be constantly monitored.

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Toaspern, Megan L. "Bioaccumulation of polychlorinated biphenyls in the Delaware River estuary". College Park, Md. : University of Maryland, 2003. http://hdl.handle.net/1903/267.

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Thesis (M.S.) -- University of Maryland, College Park, 2003.
Thesis research directed by: Marine, Estuarine, Environmental Sciences Graduate Program. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

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Melato, Aupaki Michael. "Bioaccumulation of metals in the Kuils River, Western Cape". Thesis, Cape Peninsula University of Technology, 2011. http://hdl.handle.net/20.500.11838/2013.

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Thesis (MTech (Environmental Health))--Cape Peninsula University of Technology, 2011.
World wide urban rivers are the most utilised and degraded. A variety of everyday sources of metal pollution exist that is entrenched in the modern way of life. Lately there has been a tremendous growth in the establishment and development of human settlements, both formal and informal in the Cape Town area. The surroundings of the Kuils River are not excluded from this. There are various communities in close proximity to the Kuils River. Due to this, more industries are also being established. This has caused an increased production of potential environmental pollutants, including metals. The aim of the study was firstly, to identify potential sources of metal pollution along the entire length of the Kuils River, in order to identify sampling sites. Secondly, to identify the metals contaminating the water and sediment of the Kuils River. Thirdly, to determine the bioaccumulation of metals in freshwater snails (Physa ecuta). Four sampling sites were identified along the Kuils River. Freshwater snails (P. acuta), sediment and water were collected every 2 months for a period of one year. The following metals were investigated: Aluminium (AI), Cadmium (Cd) Cobalt (Co), Chromium (Cr), Copper (Cu), Iron (Fe), Lead (Pb), Manganese (Mn), Nickel (Ni.) and Zinc (Zn). Samples were digested with 55% nitric acid. The Inductively Coupled Plasma - Atomic Emission Spectrometer (ICP-AES) were used for metal analyses. The results were statistically analysed by means of ANOVA on ranks using the Sigmastat statistical package. Results revealed that most metals found in water, sediment and snails had significantly higher concentrations at site 1. This is possibly due to input from the surrounding urban area and nearly agricultural activities. Water concentrations of AI, Cu, Mn and Zn were higher than the DWAF (1996) guidelines. Sediment was mostly contaminated with AI, Fe, Pb and Zn, while the snails contained significant levels of Cu, Fe, Mn and Zn. Further investigations involving toxicity testing should be conducted to determine the toxicity of these metals to (Physa acuta).

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Sabino, Magali. "Bioaccumulation of trace elements in Seychelles marine food webs". Thesis, La Rochelle, 2021. http://www.theses.fr/2021LAROS026.

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La sécurité alimentaire, qui est la garantie de l’approvisionnement et de la qualité des aliments tout en gérant les ressources de manière durable, est intrinsèquement liée à la connaissance de la biologie et l’écologie des espèces consommées. Dans un contexte de dérèglement climatique menaçant la salubrité des produits de la mer, il est donc nécessaire d’établir un référentiel sur le fonctionnement des systèmes marins, ainsi que sur l’occurrence des nutriments et des contaminants dans les produits de la mer. C’est d’autant plus important pour les Petits Etats Insulaires en Développement (PEID), qui dépendent des ressources marines pour leur subsistance, et où les produits de la pêche sont la première source de protéines et micronutriments (éléments traces essentiels) pour les populations locales. Malgré l’importance des systèmes tropicaux pour la sécurité alimentaire, ces systèmes sont peu étudiés comparés aux systèmes polaires et tempérés. Cette thèse vise à mieux comprendre le fonctionnement des systèmes marins tropicaux, et à établir un référentiel sur l’occurrence des micronutriments et des contaminants métalliques dans les produits de la pêche aux Seychelles (Océan Indien), un PEID tropical. En étudiant les concentrations en éléments traces aux niveaux inter- et intraspécifique, nous avons identifié différents facteurs intrinsèques et extrinsèques influençant la bioaccumulation de ces éléments dans les ressources marines tropicales. Nous avons aussi montré l’importance de considérer différentes échelles (individu, espèce et écosystème) pour mieux comprendre l’occurrence des éléments traces essentiels et non-essentiels dans les produits de la mer
Food security, that is guarantying food supply and quality while sustainably managing resources, is closely linked to knowing the biology and ecology of consumed species. In a context of global changes that are threatening seafood safety, it is thus necessary to establish baselines on marine ecosystem functioning, as well as nutrient availability and contamination occurrence in seafood. This is all the more important in Small Island Developing States (SIDS), where populations rely on marine resources for their subsistence, and where capture fisheries resources are the main sources of proteins and micronutrients (i.e. essential trace elements) in local populations’ diet. In spite of the importance of tropical systems in ensuring food security, they remain largely understudied compared to polar and temperate systems. This thesis thus aims to better understand the functioning of tropical marine systems, and to establish a baseline on micronutrient availability and metal(loid) contamination in a wide diversity of capture fisheries resources from the Seychelles (Western Indian Ocean), a tropical SIDS. By investigating trace element concentration patterns at the inter- and intraspecific levels, it was possible to identify intrinsic and extrinsic factors influencing trace element bioaccumulation in tropical capture fisheries resources. We thus highlighted the importance of considering different scales (individual, species, and ecosystem) to better understand essential trace element availability and non-essential trace element occurrence in seafood

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14

Van, Onselen Rianita. "In vivo and In vitro investigations to elucidate the associations of B-N-methylamino-L-alanine with proteins". Thesis, Nelson Mandela Metropolitan University, 2015. http://hdl.handle.net/10948/4923.

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The cyanobacterially synthesized non-canonical amino acid β-N-methylamino-ʟ-alanine (BMAA) has been proposed to be a causative agent in the development of sporadic neurodegenerative diseases. This neurotoxin bioaccumulates and biomagnifies with increasing trophic levels in ecosystems by associating with proteins. It has been suggested that these associations with host proteins also serve as a reservoir from where BMAA is slowly released with normal protein catabolism, resulting in a continuous low level exposure. However, the nature of these associations remains poorly defined. The widely accepted hypothesis regarding the nature of these associations is that BMAA associates with proteins through primary incorporation into proteins with specific replacement of serine. In addition to excitotoxicity, BMAA misincorporation has been proposed as a potential mechanism of toxicity because of its link to protein tangle diseases. Interactions between BMAA and proteins that are not the result of misincorporation, have also been observed. However, the nature of these non-primary associations has not been investigated. This study focussed on establishing whether BMAA is misincorporated into host proteins with consequent toxicity, and on elucidating the nature of the BMAA-protein associations not linked to primary incorporation. In comparative studies between BMAA and canavanine, an arginine analogue known to misincorporate, exposure to BMAA did not result in any toxicity in prokaryotes or in an undifferentiated eukaryotic mammalian cell line, in contrast to what was observed upon canavanine exposure. Differentiation of the cell line with nerve growth factor to express glutamate receptors resulted in marked toxicity upon BMAA exposure, highlighting excitoxicity as the main mechanism of BMAA toxicity. Furthermore, it was demonstrated that BMAA interacts with free amino acids and proteins in the absence of de novo protein synthesis, causing enzyme inhibition and protein misfolding. It was concluded that BMAA does not interact with proteins through primary incorporation and that the observed associations are the result of an interaction between BMAA and amino acid side chains to form covalent bonds.

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15

Drame, Abdoulaye. "Synthèse et caractérisation de tensioactifs et polymères hautement fluorés à faible potentiel bioaccumulant". Thesis, Nice, 2014. http://www.theses.fr/2014NICE4068.

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A la lumière de la bioaccumulation potentielle relative à la longueur de la chaîne fluorocarbonée, la duplication en chaines courtes constitue une technique intéressante dans la conception de nouveaux matériaux à très faible potentiel de biopersistance. Ainsi, nous avons utilisé cette méthode pour préparer de nouveaux matériaux tensioactifs et polymères conçus avec des chaînes courtes fluorées et évaluer l’influence des paramètres structuraux sur les propriétés physico chimiques de ces composés. L’évaluation des propriétés de surface des tensioactifs ont donné d’intéressantes valeurs aussi bien pour la tension de surface !!!! que pour la concentration micellaire critique (CMC) et la densité moléculaire adsorbée (Amin). La comparaison des propriétés de surface a permis de montrer, que les tensioactifs bicaténaires avec deux chaînes courtes fluorées C4F9 ou C6F13 peuvent égaler, voire dépasser les performances d’un monocaténaire à chaîne longue C8F17 réputé bioaccumulant. Deux populations d’agrégats ont été mises en évidence par la technique de la diffusion de la lumière en mode dynamique (DLS) et par microscopie électronique à transmission (TEM). Des monomères contenant deux segments fluorés ont été synthétisés. Les polymères correspondants ont ensuite été déposés par électropolymérisation et les propriétés de surface des films ont été étudiées. Des films superhydrophobes et oléophobes ont été obtenus avec le polymère PEDOT-2C4,4 à chaînes courtes du fait de nanoparticules uniformément réparties à la surface. Les performances des matériaux conçus avec deux chaînes courtes fluorées ouvrent des perspectives dans la lutte contre la bioaccumulation avérée des longues chaînes perfluorées
In the light of the potential bioaccumulation relative to the length of the fluorocarbon chain, duplication short chains is an interesting technique in the design of new materials with very low biopersistance. Thus, we used this method to prepare novel surfactants and polymeric materials designed with fluorinated short chains and assess the influence of structural parameters on the physicochemical properties of these compounds. The evaluation of surface properties of surfactants gave interesting values for both surface tension !!!!, critical micelle concentration (CMC) and the molecular density adsorbed (Amin). Comparison of surface properties have shown that double-tailed short chains surfactants with two fluorinated C4F9 or C6F13 can match or exceed the performance of a single-tailed long chain C8F17 deemed bioaccumulant. These surfactants gave two aggregate populations identified by the technique of dynamic light scattering (DLS) and TEM images (transmission electron microscopy). Fluorinated monomers containing two segments were synthesized. The corresponding polymers were then deposited by electropolymerization and the films were studied. Oleophobic and superhydrophobic films were obtained with the PEDOT-2C4,4 polymer short chains because nanoparticles uniformly distributed on its surface. Performance materials designed with two short chain fluorinated open perspectives in the context of the fight against bioaccumulation proven long perfluorinated chains

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16

Aharchaou, Imad. "Écotoxicité et bioaccumulation du Cr(III) et du Cr(VI) : spéciation, biodisponibilité et effets biologiques". Thesis, Université de Lorraine, 2017. http://www.theses.fr/2017LORR0014/document.

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L’écotoxicité des éléments traces vis-à-vis du vivant est contrôlée par leur bioaccessibilité, leur biodisponibilité et leurs interactions avec le(s) site(s) d’action à l’intérieur des organismes. Dans le cas des certains éléments, l’existence dans le milieu naturel de plusieurs formes redox ayant des propriétés différentes doit aussi être prise en considération. Dans le cas spécifique du Cr, le consensus général considère le Cr(III) comme moins écotoxique que le Cr(VI). Toutefois, plusieurs études récentes soulignent que ce consensus devrait être réexaminé. Plus particulièrement, une connaissance insuffisante de la spéciation du Cr(III) pendant les tests en laboratoire pourrait avoir conduit à une sous-estimation de sa biodisponibilité et écotoxicité. Ce travail de thèse s’intéresse donc aux relations entre spéciation, biodisponibilité et bioaccumulation du Cr(III) et Cr(VI) dans différents modèles biologiques pour mieux appréhender leur potentiel écotoxique ainsi que leurs mécanismes d’interaction avec le vivant. Des études ont été menées chez les algues Pseudokirchneriella subcapitata et Chlamydomonas reinhardtii, le bivalve Corbicula fluminea et des cultures de cellules d’ovaire d’hamster chinois (CHO). L’ensemble des résultats de ce travail suggère que la validité du paradigme ‘le Cr(VI) est plus écotoxique que le Cr(III)’ serait dépendante des conditions d’exposition et du modèle biologique utilisé. Ce paradigme, accepté tant par la communauté scientifique que par les gestionnaires environnementaux, nécessite donc un réexamen afin d’assurer une meilleure gestion des risques liés au Cr
The ecotoxicity of the trace elements to the living organisms is controlled by their bioaccessibility, their bioavailability and their interactions with the site(s) of action inside the organisms. In the case of certain elements, the existence in the natural environment of several redox forms having different properties must also be taken into consideration. In the specific case of Cr, general consensus considers Cr(III) to be less ecotoxic than Cr(VI). However, several recent studies highlight that this consensus should be re-examined. In particular, insufficient knowledge of Cr(III) speciation during laboratory tests may have led to an underestimation of its bioavailability and ecotoxicity. This work focuses on the relationship between speciation, bioavailability and bioaccumulation of Cr(III) and Cr(VI) in different biological models in order to better understand their ecotoxic potential as well as their mechanisms of interaction with living organisms. Studies have been conducted on the algae Pseudokirchneriella subcapitata and Chlamydomonas reinhardtii, the bivalve Corbicula fluminea and cultures of Chinese hamster ovary cells (CHO). The results of this work suggest that the validity of the paradigm ‘Cr(VI) is more ecotoxic than Cr(III)’ would be dependent on the exposure conditions and the used biological model. This paradigm, accepted by both the scientific community and the environmental managers, requires a reassessment to ensure a better management of Cr risks

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Bertin, Delphine. "Transfert des composés perfluorés des sédiments aux invertébrés benthiques". Thesis, Lyon 1, 2014. http://www.theses.fr/2014LYO10274.

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L'accumulation de composés persistants dans le biote constitue des préoccupations écologiques, sanitaires et réglementaires. Parmi ces substances, les composés per- et polyfluorés (PFASs) représentent un cas d'intérêt, en raison de leurs propriétés physico-chimiques particulières. Ces dernières rendent le comportement des PFASs dans l'environnement difficilement prévisibles, les outils actuels n'étant pas adaptés. Bien qu'il soit reconnu que ces composés sont persistants et s'accumulent dans le biote, de nombreuses inconnues subsistent, notamment sur les mécanismes de transferts sédiment–biote et des facteurs qui les contrôlent. Ce travail de thèse aborde le rôle du sédiment dans les processus d'accumulation, et plus particulièrement (a) les voies d'exposition du biote, (b) le rôle de la diversité biologique dans l'accumulation, par l'exposition de deux invertébrés benthiques (Chironomus riparius et gammarus sp.) à du sédiment naturel. La description des cinétiques d'accumulation et d'élimination des PFASs ont mis en évidence la biodisponibilité des composés pour les organismes. Ainsi, un modèle de bioaccumulation en accord avec la croissance des organismes et des particularités des composés a permis d'estimer des constantes d'accumulation et de dépuration (ku et ke). Une représentation conceptuelle du transfert des composés, a permis de comprendre les principales voies de contamination des organismes. D'autre part, la variabilité interspécifique a été évaluée par la comparaison de la bioaccumulation et des voies de transfert des PFASs chez ces deux invertébrés. Ce travail de thèse aura alors permis d'ouvrir de nombreuses questions, notamment celles du rôle du biofilm et de la bioturbation des organismes dans la bioaccumulation et ouvre les perspectives quant à l'étude de la bioamplification
The accumulation of persistent compounds in biota creates environmental, health and regulatory concerns. Among these substances, the poly-fluorinated compounds (PFASs) represents a case of interest due to their specific physicochemical properties. So the PFAs behavior in the environment is difficult to predict as the existing tools are not suitable. Athough it is recognized that these compounds are persistent and accumulate in biota, many knowledge gaps remain, including the mechanisms of sediment-biota transfer and the factors that control them. This thesis examines the role of sediment in the accumulation process, especially (a) exposure routes of biota, (b) role of biodiversity in the accumulation, by exposing two benthic invertebrates (Chironomus riparius and Gammarus sp.) to natural sediment. The description of PFASs kinetics of accumulation and elimination have showed the biodisponibility of the compounds to organisms. Thus, a bioaccumulation model including the organisms growth and the specificity of the compounds was used to estimate the accumulation and depuration rate constants (ku and ke). A conceptual representation of compounds transfer allowed us to understand the major routes for organisms contamination. Moreover, the interspecific variability has been assessed by comparing the PFASs bioaccumulation and transfer pathways for both invertebrates. This thesis have helped to open up many issues, and especially the influence of both biofilm and organism bioturbation onPFASs bioaccumulation. Moreover some new perspectives on the study of biomagnification were opened

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18

Moore, Margaret Heather. "Feeding and bioaccumulation of trace metals in deep sea holothurians". Thesis, Queen's University Belfast, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241421.

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Lack, Barbara Anne. "Electrochemical studies of gold bioaccumulation by yeast cell wall components". Thesis, Rhodes University, 1999. http://hdl.handle.net/10962/d1004969.

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Gold, amongst other group 11 metals, was almost certainly one of the first three metals known to man. In addition to the economic importance of the metal, gold has a wide variety of applications in the medical, electrocatalytical and micro-electronics fields. However, the determination of gold ions in solution, with accuracy, precision, sensitivity and selectivity is still an interesting and much debated topic in analytical chemistry. A system whereby gold ions have been successfully detected employing an electrochemical technique, known as stripping voltammetry, has been developed. The electrochemical method was chosen over other available techniques for the sensitivity, particularly at low concentrations, and selectivity properties; notably in the presence of other metal ions. Under acidic conditions, the electrochemical technique was applied and the presence of gold(III), at a concentration of 2.53 x 10⁻⁵ mol dm⁻³ in a mine waste water sample, was detected. Biomass, in particular yeast and algal types, have been successfully employed in extracting low concentrations of gold ions from industrial effluents. The manipulation of the biological facility for mineral interaction, biohydrometallurgy, may yield numerous potential new technologies. South Africa in particular would benefit from this area of research, since the country is a major ore and metal refining country and if the output and the efficiency of the mines could be improved, even by a small percentage, the financial rewards would be vast. In this study, the application of adsorptive cathodic stripping voltammetry (AdCSV) of gold(III) in the presence of various Saccharomyces cerevisiae cell wall components, was investigated to determine which, if any, were involved specifically in the chemical binding of the gold ions. The chitin and mannan extracts showed the most promise with detection limits of 1.10 x 10⁻⁶ mol dm⁻³ and 9 x 10⁻⁹ mol dm⁻³, respectively; employing the AdCSV technique. A modification of the stripping voltammetry technique, Osteryoung square wave stripping voltammetry (OSWSV), provided the lowest detection limit, for gold(IIl) in the presence of mannan, of 1.70 x 10⁻¹¹ mol dm⁻³ ; utilising a modified carbon paste electrode. The detection of gold(III) has been shown to be dependent on the type of electrode employed, the electrolyte solution and the presence of interfering agents. The effect of copper(II) and silver(I) on the detection of the gold(III) in solution was investigated; whilst the silver(I) has shown no detrimental effects on gold (III) detection systems, copper(II) has indicated the possibility of forming an inter-metallic compound with the gold(III). However, mannan has shown to selectively and preferentially bind the gold(III) in the presence of a ten-fold excess of copper(II). Nuclear magnetic resonance (NMR) and infrared (IR) spectroscopy, as well as computer modelling techniques were employed to further investIgate the mannan-gold(III) interaction and proposed complex formed. The NMR, IR and computer modelling data are in agreement with the electrochemical data on proposing a mannan-gold(III) complex. The co-ordination site was established to be in the vicinity of the H-I and H-2 protons and the gold(III) adopts a square-planar geometry upon co-ordination. The benefits of the research are useful from a biological perspective (i. e. as more is known about the binding sites, microbiologists/biochemists may work on the optimisation of parameters for these sites or work could be furthered into the enhanced expression of the sites) and an industrial one. In addition to the' two major benefits, an improved understanding of gold and its chemistry would be achieved, which is advantageous for other fields of research as well.

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20

Fallahi, Fahimeh. "Bioaccumulation and Neuroinflammation of GoldNanoparticles in the Central Nervous System". Wright State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=wright1369756360.

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Walker, Rachel Alex. "Methylmercury Bioaccumulation in Spotted Salamanders (Ambystoma maculatum) in Southern Ohio". Wright State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=wright1496084470204606.

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Brady, Dean. "Bioaccumulation of metal cations by yeast and yeast cell components". Thesis, Rhodes University, 1993. http://hdl.handle.net/10962/d1004107.

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The aim of the project was to determine whether a by-product of industrial fermentations, Saccharomyces cerevisiae, could be utilized to bioaccumulate heavy metal cations and to partially define the mechanism of accumulation. S. cerevisiae cells were found to be capable of accumulating Cu²⁺in a manner that was proportional to the external Cu²⁺ concentration and inversely proportional to the concentration of biomass. The accumulation process was only minimally affected by temperature variations between 5 and 40°C or high ambient concentrations of sodium chloride. The accumulation process was however considerably affected by variations in pH, bioaccumulation being most efficient at pH 5 - 9 but becoming rapidly less so at either extreme of pH. Selection for copper resistant or tolerant yeast diminished the yeast's capacity for Cu²⁺ accumulation. For this and other reasons the development of heavy metal tolerance in yeasts was deemed to be generally counterproductive to heavy metal bioaccumulation. The yeast biomass was also capable of accumulating other heavy metal cations such as c0²⁺ or Cd²⁺. The yeast biomass could be harvested after bioaccumulation by tangential filtration methods, or alternatively could be packed into hollow fibre microfilter membrane cartridges and used as a fixed-bed bioaccumulator. By immobilizing the yeast in polyacrylamide gel and packing this material into columns, cu²⁺, C0²⁺ or Cd²⁺ could be removed from influent aqueous solutions yielding effluents with no detectable heavy metal, until breakthrough point was reached. This capacity was hypothesized to be a function of numerous "theoretical plates of equilibrium" within the column. The immobilized biomass could be eluted with EDTA and recycled for further bioaccumulation processes with minor loss of bioaccumulation capacity. Yeast cells were fractionated to permit identification of the major cell fractions and molecular components responsible for metal binding. Isolation of the yeast cell walls permitted investigation of their role in heavy metal accumulation. Although the amino groups of chitosan and proteins, the carboxyl groups of proteins, and the phosphate groups of phosphomannans were found to be efficient groups for the accumulation of copper, the less effective hydroxyl groups of the carbohydrate polymers (glucans and mannans) had a similar overall capacity for copper accumulation owing to their predominance in the yeast cell wall. The outer (protein-mannan) layer of the yeast cell wall was found to be a better Cu²⁺ chelator than the inner (chitinglucan) layer. It appeared that the physical condition of the cell wall may be more important than the individual macromolecular components of the cell wall in metal accumulation. It was apparent that the cell wall was the major, if not the sole contributor to heavy metal accumulation at low ambient heavy metal concentrations. At higher ambient metal concentrations the cytosol and vacuole become involved in bioaccumulation. Copper and other metals caused rapid loss of 70% of the intracellular potassium, implying permeation of the plasma membrane. This was followed by a slower "leakage" of magnesium from the vacuole which paralleled Cu²⁺ accumulation, suggesting that it may represent some form of ion-exchange. An intracellular copper chelating agent of approximately 2 kDalton molecular mass was isolated from copper tolerant yeast. This chelator was not a metallothionein and bound relatively low molar equivalents of copper compared to those reported for metallothionein. Treatment of the biomass with hot alkali yielded two biosorbents, one soluble (which could be used as a heavy metal flocculent), and an insoluble biosorbent which could be formed into a granular product to be used in fixed-bed biosorption columns. The granular biosorbent could accumulate a wide range of heavy metal cations in a semispecific manner and could be stored in a dehydrated form indefinitely, and rehydrated when required. Bioaccumulation by live algae was investigated as an alternative to yeast based processes. Various strains of algae, of which Scenedesmus and Selenastrum were the most effective, were found to be capable of accumulating heavy metals such as Cu²⁺, Pb²⁺ and Cr³⁺.

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Okumura, Yutaka. "Mass Balance and Bioaccumulation of Major Dioxins in Sendai Bay". Kyoto University, 2011. http://hdl.handle.net/2433/135409.

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Rattfelt, Nyholm Jenny. "Persistency, bioaccumulation and toxicity assessment of selected brominated flame retardants". Doctoral thesis, Umeå : Department of Chemistry, Umeå University, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-22528.

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Farren, Alex. "Mercury and selenium speciation and toxicity in common loons". Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=81331.

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Approximately 10,000 tones of Hg are deposited annually as a result of anthropogenic activities. This increased Hg burden is known to have adverse neurological and reproductive effects on Common loons. A positive correlation between mercury (Hg) and selenium (Se) has been reported to exist in marine mammals and various species of marine and aquatic piscivorous birds. It has been hypothesized that the Hg/Se interactions may involve in the multiple mechanisms of Hg detoxification. This study focused on the suggested Hg/Se complex that forms in association with specific proteins. Specifically, this project focuses on the nature of these interactions in different tissues from wild Common loons (Gavia immer) that have been collected by the Canadian Wildlife Service. The Hg and Se concentrations in the various tissues were quantified using AAS. MALDI-TOF-MS and protein sequencing characterized the nature of the Hg/Se complex binding protein. Among the tissues, the liver had the highest concentrations of Hg and Se followed by kidney; muscle and brain. A strong association between Hg and Se was found in liver, kidney and eggs whereas there was no association in muscle and brain. In contrast brain and muscle had highest percentage of organic Hg suggesting that only inorganic Hg is associated with Se. Two Hg-Se binding protein complexes were found in liver both in the 15,200-15,300 Da range while one such complex in the same weight range was found in kidneys, when sequenced it was found that these proteins were the alpha A chain of Hemoglobin. The protein complex found in eggs was unique and although it was impossible to fully sequence it, it represents an unknown protein. The role of Se in Hg toxicity in eggs warrants further study.

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Brockmann, Sina, Thuro Arnold i Gert Bernhard. "Wechselwirkung von Uran(VI) mit Biofilmen". Forschungszentrum Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-129994.

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Natürliche Biofilme von zwei urankontaminierten Standorten, dem ehemaligen Uranbergwerk in Königstein (Sachsen) und dem Gebiet der ehemaligen Aufstandsfläche der Gessenhalde (Thüringen), wurden in dieser Arbeit näher untersucht. An beiden Standorten konnte in den Minenwässern die hochmobile, gelöste Uranspezies Uranylsulfat (UO2SO4) als dominierend nachgewiesen werden. Aufgrund der Instabilität vieler kommerzieller Fluoreszenzfarbstoffe bei niedrigen pH-Werten war eine gezielte Anfärbung der Mikroorganismen in den sauren Biofilmen nicht möglich, ohne den pH-Wert der Biofilmproben anzuheben, was die Probenchemie maßgeblich verändert. In Kooperation mit der Firma DYOMICS (Jena, Deutschland) wurden neue, kommerziell nicht erhältliche, säurestabile Farbstoffe erstmals hinsichtlich ihrer Eignung zur Anfärbung von Mikroorganismen in sauren Biofilmen ohne Veränderung des pH-Wertes sowie der sonstigen Probenchemie getestet. Die neuen Farbstoffe DY-601XL, V07-04118, V07-04146 und DY-613 zeigten eine Eignung für solche Färbungen, da sie eine intensive Anfärbung der Mikroorganismen bei niedrigen pH-Werten unter pH 3 – 4 herbeiführen und außerhalb des Emissionsbereiches von Uran fluoreszieren. In dieser Arbeit wurde die Fähigkeit von Euglena Mutabilis-Zellen zur Bioakkumulation des Urans im pH-Wertbereich 3 – 6 in den Hintergrundmedien Natriumperchlorat (9 g/l) oder Natriumsulfat (3,48 g/l) an lebenden Zellen untersucht. Unabhängig vom Medium konnte bei sauren pH-Werten um pH 3 – 4 über 90 % des vorgelegten Urans aus den Probelösungen abgetrennt werden. Die Speziation des an den Euglena-Zellen akkumulierten Urans, wurde mittels laserinduzierter Fluoreszenzspektroskopie (LIFS) untersucht. Es zeigte sich, dass unabhängig vom Hintergrundmedium, Lebenszustand und pH-Wert eine vergleichbare neue Uranspezies an den Zellen gebildet wird. Durch den Vergleich der Daten aus den LIFS-Messungen mit Referenzwerten, konnte die gebildete Uranspezies auf eine Anbindung durch (organo)phosphatische und/oder carboxylische funktionelle Gruppen eingegrenzt werden. Mit Hilfe der zeitaufgelösten FT-IR-Spektroskopie konnte die carboxylische Anbindung des Urans an toten Zellen nachgewiesen werden. Ein Ausschluss der (organo)phosphatischen Komplexierung konnte jedoch mit dieser Methode nicht geführt werden. Untersuchungen zur Lokalisation des Urans an bzw. in den Zellen, mittels der gekoppelten CLSM/LIFS-Technik zeigten erstmals ein Indiz für die intrazelluläre Akkumulation von Uran in den lebenden Zellen. Ergänzende TEM/EDX-Messungen bestätigten die intrazelluläre Aufnahme und belegen eine Akkumulation in runden bis ovalen Zellorganellen, bei denen es sich vermutlich um Vakuolen oder Vakuolen-ähnliche Vesikel handelt. An den toten Zellen konnte mit diesen Methoden kein Uran detektiert werden. Dies lässt auf eine passive, homogen verteilte Biosorption des Urans an die verfügbaren Bindungsplätze an der Zelloberfläche der toten Biomasse schließen.

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Gentès, Sophie. "Les microorganismes colonisant les racines de plantes aquatiques dans les écosystèmes landais : diversité et risques liés à la méthylation du mercure". Thesis, Pau, 2012. http://www.theses.fr/2012PAUU3041/document.

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Le mercure (Hg) est un polluant métallique préoccupant de par sa toxicité et son omniprésence dans les écosystèmes aquatiques. Sous sa forme méthylée, il est capable de se bioaccumuler dans les organismes et d’être bioamplifié le long de la chaîne trophique. La méthylation du Hg est un processus biotique principalement attribué aux microorganismes sulfato-réducteurs (MSR). La rhizosphère des plantes aquatiques a été récemment identifiée comme un compartiment privilégié de la méthylation du Hg dans certains écosystèmes tropicaux et boréaux. Les objectifs de cette étude étaient de déterminer l’influence des plantes aquatiques sur la biogéochimie et la bioaccumulation du Hg et le rôle que jouent les MSR dans ce processus au sein des écosystèmes aquatiques landais. L’utilisation de traceurs isotopiques stables du Hg a permis d’identifier le compartiment « plantes aquatiques » comme un lieu privilégié des transformations des espèces mercurielles (méthylation/ déméthylation du Hg) et comme la principale source de méthylmercure (MeHg) dans ces écosystèmes tempérés. La combinaison des approches moléculaires (T-RFLP, clonage, séquençage) et culturales (isolement, détection de MeHg par biosenseur) a démontré l’implication de MSR du genre Desulfovibrio dans le processus de méthylation du Hg au sein de la rhizoplane aquatique. D’après une expérience menée en microcosmes utilisant un traceur isotopique du Hg, le MeHg formé au niveau de la rhizosplane aquatique serait biodisponible pour la chaîne trophique. Cette dernière observation est à relier à des concentrations en Hg significatives, observées in situ, pour certains poissons de fin de chaîne alimentaire
Mercury (Hg) is a metallic pollutant worrying because of its toxicity and ubiquity in aquatic ecosystems. Its organic form is easily bioaccumulated in organisms and biomagnified along food webs. Hg methylation is a biotic process mainly attributed to sulfate-reducing prokaryotes (SRP). The rhizoplane of aquatic plants has recently been identified as the principal compartment involved in Hg methylation in some tropical and boreal ecosystems. The objectives of this study were to determine the influence of aquatic plants on the biogeochemistry and bioaccumulation of Hg and the role of SRP in this process in the aquatic ecosystems of the Landes (South Western France). The use of Hg stable isotopic tracers allowed to identify the "aquatic plants" compartment as the main place for Hg species transformations (methylation / demethylation of Hg) and the main source of methylmercury (MeHg) in these temperate ecosystems. The combination of molecular (T-RFLP, cloning, sequencing) and cultural (isolation, MeHg detection by biosensor) approaches demonstrated the involvement of populations related to the genus Desulfovibrio in the process of Hg methylation in the aquatic rhizoplane. According to an experiment conducted in microcosms using a Hg isotopic tracer, MeHg formed in the aquatic rhizoplane seems to be bioavailable to the food chain. This last observation is linked to significant Hg concentrations, observed in situ, for some carnivorous fishes (end of the food chain)

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Sánchez, Marina. "Les composés organochlorés dans la nourriture". Master's thesis, Université Laval, 2006. http://hdl.handle.net/20.500.11794/18222.

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Reitz, Thomas. "U(VI) bioaccumulation by Paenibacillus sp. JG-TB8 and Sulfolobus acidocaldarius". Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2012. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-83242.

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In this thesis, the interactions of U(VI) with one representative each of the domains Bacteria (Paenibacillus sp. JG TB8) and Archaea (Sulfolobus acidocaldarius) are compared. We demonstrate that at highly acidic conditions (pH ≤ 3), U(VI) is bound to cells of the both strains exclusively via organic phosphate groups. In contrast to this, the U(VI) complexation modes differ between the studied strains at moderate acidic conditions. These differences are assigned to the different cell wall structures of both strains as well as to their different physiological characteristics. We also demonstrate that the aeration conditions can strongly influence the uranium accumulation of facultative anaerobic microorganisms at moderate acidic pH conditions. This finding could clearly be assigned to the dependency of the intrinsic phosphatase activity on the aeration conditions. The second part of this thesis deals with the outermost surface layer (SlaA-layer) of S. acidocaldarius. It was shown that this surface protein is not involved in the U(VI) complexation at highly acidic conditions, covering the physiological pH optimum of S. acidocaldarius. Hence the SlaA layer does not provide a protective function against U(VI) to the cells of this acidophilic archaeon. However, we demonstrated that purified SlaA-layer ghosts (i.e. empty cell sacculi) efficiently interact with gold ions and are a good macromolecular template for the formation of magnetic gold nanoparticles
In dieser Doktorarbeit werden die Wechselwirkungen von U(VI) mit je einem Vertreter der Bakterien (Paenibacillus sp. JG TB8) und Archeen (Sulfolobus acidocaldarius) verglichen. Wir konnten zeigen, dass U(VI) im sehr sauren Milieu (pH ≤ 3) ausschließlich durch organische Phosphatgruppen an die Zellen beider Stämme gebunden ist. Im Gegensatz dazu unterscheiden sich die Mechanismen der U(VI)-Komplexierung beider untersuchter Stämme bei mäßig sauren Bedingungen voneinander. Diese Unterschiede basieren auf den unterschiedlichen Zellwandstrukturen und physiologischen Eigenschaften beider Stämme. Wir konnten außerdem zeigen, dass die atmosphärischen Bedingungen die Urankomplexierung durch fakultativ anaerobe Mikroorganismen bei mäßig sauren Bedingungen stark beeinflussen kann. Dieses Ergebnis konnte eindeutig auf die von den atmosphärischen Bedingungen-abhängige, enzymatische Aktivität der zelleigenen Phosphatase zurückgeführt werden. Der zweite Teil dieser Arbeit beschäftigt sich mit der äußeren Oberflächenschicht (SlaA-layer) von S. acidocaldarius. Es konnte gezeigt werden, dass dieses Oberflächenprotein nicht an der U(VI)-Komplexierung bei stark sauren pH, welcher dem physiologischen pH Optimum von S. acidocaldarius entspricht, beteiligt ist. Damit stellt der SlaA-layer keinen Schutz gegen Uran für die Zellen dieses azidothermophilen Archaeons dar. Allerdings konnten wir zeigen, dass isolierte „SlaA-layer ghosts“ (d.h. leere Zellhüllen) mit Goldionen interagieren und sich daher als makromolekulares Template für die Herstellung magnetischer Gold Nanopartikel eignen

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Cai, Yan. "Bioaccumulation of mercury in pelagic fishes in NW Gulf of Mexico". Texas A&M University, 2003. http://hdl.handle.net/1969.1/3847.

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Total mercury (Hg) levels were determined in the tissues of ten taxa of pelagic fishes, with a special emphasis on apex predators (large vertebrates). Highest Hg levels were observed in blue marlin (Makaira nigricans), carcharhinid sharks (Genus Carcharhinus) and little tunny (Euthynnus alletteratus), ranging from 1.08 to 10.52 ppm. Moderate to low concentrations (<1.0 ppm) were observed in blackfin tuna (Thunnus atlanticus), cobia (Rachycentron canadum), dolphinfish (Coryphaena hippurus), greater amberjack (Seriola dumerili), king mackerel (Scomberomorus cavalla), wahoo (Acanthocybium solandri) and yellowfin tuna (Thunnus albacares). For the majority of species examined, Hg level did not vary significantly between locations (Texas and Louisiana) and years (2002 and 2003). The relationship between Hg level and fish size/weight was also explored and six taxa (blackfin tuna, carcharhinid sharks, dolphinfish, king mackerel, wahoo, yellowfin tuna) showed significant positive relationships between Hg level and body size and/or weight. Natural dietary tracers, stable isotopes (15N, 13C) and fatty acids were used to evaluate the relationship between Hg and trophic position and the relationship between Hg and dietary history. Stable nitrogen isotope analysis showed that Hg levels in fish tissues were positively associated with trophic position. Based on the 13C and 15N values of pelagic consumers examined in this study, three natural groups were identified with cluster analysis, and the same groupings were detected based on fatty acid profiles. This not only confirmed the existence of these natural groupings, but also indicated that the distinguishing factors for the grouping was likely connected with the dietary history of these fishes. The classification tree based on the fatty acid profiles of pelagic fishes readily separated fishes from different regions, suggesting that diets of pelagic taxa within the same region are similar or these consumers share a common source of organic matter in their food web. Findings from this study complement other Hg investigations conducted in the Gulf and also furthered our understanding of the link between feeding ecology and Hg accumulation. Moreover, the combined use of stable isotope and fatty acid techniques provided new insights on the dietary history of pelagic fishes in the Gulf of Mexico.

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Kelly, Barry C. "Bioaccumulation potential of organic contaminants in an Arctic marine food web /". Burnaby B.C. : Simon Fraser University, 2006. http://ir.lib.sfu.ca/handle/1892/2662.

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Thesis (Ph.D.) - Simon Fraser University, 2006.
Theses (School of Resource and Environmental Management) / Simon Fraser University. Senior supervisor : Dr. Frank A. P. C. Gobas. Included bibliographical references : leaves 226-248.

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Colegate, Rachel Marie. "A biophysical study of surfactants: an assessment of bioaccumulation and toxicity". Thesis, University of Kent, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.484072.

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Wright, David A. "A multifactorial approach to trace bioaccumulation and survival in estuarine organisms". Thesis, University of Newcastle Upon Tyne, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248473.

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Zhao, Shizhen. "Modelling the fate and bioaccumulation potential of organic chemicals in China". Thesis, Lancaster University, 2016. http://eprints.lancs.ac.uk/79146/.

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An extensive array of chemicals are used in industry and commerce, many produced in large volumes, but their fate in the environment and corresponding exposure to organisms (including humans) has only been measured for a limited number of substances. Modelling tools have been demonstrated to be an economical alternative to measurement data for the assessment of chemical fate and exposure. Therefore, many fate and bioaccumulation models have been developed in Western countries while progress on the development of tools and legislation are relatively far behind in China. In this thesis, the application of modelling tools in environmental fate and exposure assessment of organic pollutants has been explored in China. The first aspect of this research was the adaptability of Western dietary exposure models to the Chinese population. In Paper I, three established Western-based exposure models were used for China using specific Chinese dietary scenarios and modified human characteristics to explore their potential adaptability to be used for the Chinese population. The second aspect was to explore the possibility of extending existing bioaccumulation models to a wider range of organic pollutants by incorporation of newly developed poly-parameter linear free energy relationships (pp-LFERs) for individual biological phases in Paper II. Compared to traditional single parameter(sp) KOW-based (sp-LFERs) methods, the pp-LFERs only indicated limited advantages when evaluated with measurements, implying that the choice of approach should be based on other factors beyond methodology of calculating partitioning coefficients (e.g.,accuracy of input data and uncertainty from biotransformation). The studies described in Paper III and Paper IV took polychlorinated biphenyls (PCBs) as a case study, to comprehensively evaluate and demonstrate the ability of a global dynamic fate model （BETR-Global） linked to a bioaccumulation model (ACC-HUMAN) in the reconstruction of historical trends and predicting future of emission trends and exposure profiles for the Chinese population. Meanwhile, controlling sources of intentional and unintentional emissions were thoroughly explored within China in Paper III. Paper IV more focused on human exposure under the combined effect of emission trends and dietary transition for the Chinese population. The delayed peak time of the human body burden of PCBs has mainly been caused by rapid dietary shifts and on-going emissions from sources, such as imported e-waste in China. The Large uncertainty in the prediction of human body burdens suggests that the choice of model system could be relevant for exposure assessment and that the model should be tailored to the system of interest. Finally, preliminary suggestions to conduct effective controlling measures were also made for the policy makers.

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Sloterdijk, H. "Utilisation des jeunes poissons comme indicateurs de bioaccumulation des substances toxiques". Toulouse 3, 1992. http://www.theses.fr/1992TOU30084.

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Lorsqu'on utilise les poissons adultes comme indicateurs de bioaccumulation des substances chimiques toxiques persistantes, il y a souvent une grande variabilite de donnees. Le present ouvrage presente une alternative a l'emploi de poissons adultes pour l'evaluation de la bioaccumulation des contaminants du milieu aquatique, soit l'utilisation de jeunes poissons de l'annee comme bioindicateurs a cette fin. Le queue a tache noire (notropis hudsonius) a ete choisie comme espece cible et deux especes de remplacement ont ete retenues, a savoir la perchaude (perca flavescens) et le mene emeraude (notropis atherinoides). Les trois especes ont ete prises dans le fleuve saint laurent au quebec, lors de quatre annees successives. On a evalue les facteurs qui peuvent influencer l'utilisation de ces bioindicateurs, comme les differences de longueurs, la periode de l'annee durant laquelle l'echantillonnage est fait, leur teneur en lipides, la taille de l'echantillon, les variations entre stations et la specificite par site. Les contaminants etudies comprenaient les metaux lourds (hg, cd, pb, cu, zn, cr, ni), deux metalloides (as, se) et les composes organochlores (pcb, dde, hcb, hch, aldrine, mirex et heptachlore). Les resultats ont demontre que ces bioindicateurs etaient tres regio specifiques, manifestaient une variabilite intra station faible et pouvaient identifier des sources ponctuelles, alors qu'un modele de regression permettait la conversion des concentrations de contaminants entre especes. Donc, les jeunes poissons de l'annee peuvent etre utilises comme des indicateurs fiables et rapides de la concentration environnementale et des tendances spatio temporelles

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Anane, Rachid. "Mise en évidence du passage transcutané de l'aluminium bioaccumulation et neurotoxicité". Bordeaux 2, 1996. http://www.theses.fr/1996BOR2B005.

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Arantes, Irène. "Bioaccumulation du mercure dans la rivière Das Velhas, Minas Gerais, Brésil". Lyon 1, 2008. http://www.theses.fr/2008LYO10058.

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Le bassin de la rivière Das Velhas s’étend sur 29. 173 Km2 à travers l’état brésilien de Minas Gerais. Il a fourni un soutien économique et des emplois aux membres d’innombrables communautés de pêcheurs riverains. Cependant, la pollution chimique et les égouts provenant des fermes, de l’industrie et des villes en cours de développement rapide le long de la rivière ont un sérieux impact sur la qualité de l’eau et de l’environnement. Aussi, cette étude a été réalisée pour constater la présence de mercure total dans l’eau, les sédiments, les plantes et les tissus de 39 espèces de poissons collectés en divers points au long d’une rivière atelier du Brésil : la rivière « Das Velhas ». Afin de quantifier cette contamination, nous avons dosé le mercure total au moyen d’un analyseur modèle AMA 254 (Automated Mercury Analysis system). La variété de poissons collectée et étudiée regroupait des espèces détritivores, herbivores, omnivores et carnivores, migratoires ou sédentaires. La concentration de mercure dans l’eau, les sédiments, les plantes et les poissons dans le bassin de la rivière Das Velhas a révélé différents niveaux de contamination et de telles observations suggèrent un état de contamination de la zone étudiée au point de vue biologique. La variation des niveaux de mercure entre les différents tissus, tels que les branchies, la peau, les gonades, l’intestin, le cœur, l’estomac, le foie, la vessie, le muscle, les yeux, le rein et la vésicule de toutes les espèces étudiées a été examinée au niveau de la bioaccumulation, de la biotransformation et de l’élimination. Le rein et le cœur sont apparus comme étant les organes préférentiels pour l’accumulation du mercure. La vessie a été l’organe le moins affecté en termes de bioaccumulation du mercure. Les espèces omnivores et carnivores ont présenté les plus hautes concentrations en mercure tandis que les espèces herbivores et détritivores étaient les moins contaminées par cet élément. L’accumulation de mercure dans ces différents tissus chez un grand nombre d’espèces représente un risque potentiellement réel pour les organismes qui s’en nourrissent. Les données obtenues permettent d’avoir un panoramique de la contamination d’une rivière en mercure où les activités humaines et agricoles sont importantes dans tous les compartiments environnementaux, montrant que des actions significatives doivent être entreprises pour sauvegarder les sites dans le cadre du développement durable
The Rio das Velhas (Velhas River) basin stretches 29. 173 Km2 through the Brazilian state of Minas Gerais. It has provided economic support and jobs for members of the countless fishing communities along its banks. However, chemical and sewage pollution from farms, industry and rapidly growing towns along the river is having a serious impact on water quality. A survey was made on total Hg in water, sediment, plant and the tissues of 39 fish species collected along Rio das Velhas. The total mercury was analyzed using AMA 254 (Automated Mercury Analysis system). The species taken into consideration included detritivores, herbivores, omnivores and carnivores species, as well as migrating and sedentary species with different periods of maturation. The mercury concentration in water, sediment, plant and fish along the Rio das Velhas basin revealed different levels of contamination and such occurrences suggest a contamination condition of the study are. The variation in mercury levels between the different tissues, such as gills, skin, gonads, intestine, heart, stomach, liver, bladder, muscle, eye, kidney and blisters from all species studied are discussed in regard to storage, biotransformation and elimination. The kidney and heart appear to be the preferential organ for mercury accumulation. The bladder is the least affected organ in terms of mercury uptake. The species omnivores and carnivores had higher mercury concentrations while the species herbivores and detritivores had the lowest level of this element. Accumulation of mercury contaminants in all those different tissues in the many species represents a potentially realistic hazard to organisms that feed on them

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Lemaire, Jérémy. "Mercury contamination in caimans from French Guiana, bioaccumulation and physiological effects". Thesis, La Rochelle, 2021. https://tel.archives-ouvertes.fr/tel-03716076.

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Le mercure (Hg) est un contaminant environnemental qui affecte tous les écosystèmes. Il a la particularité de se biomagnifier le long de la chaîne trophique et de se bioaccumuler dans les tissus des prédateurs. Le Hg est connu pour avoir des effets néfastes chez les humains et la faune sauvage. Les prédateurs des écosystèmes tropicaux sont particulièrement affectés par la contamination en Hg du fait de l’exploitation aurifère artisanale qui utilise d’importantes quantités de Hg pour extraire l’or. Les crocodiliens sont des super-prédateurs des écosystèmes tropicaux et ils accumulent de fortes concentrations de Hg dans leurs tissus. Ils sont potentiellement de bons candidats pour suivre la contamination en Hg, ce sont des animaux vivant plusieurs décennies, ils ont un métabolisme lent et un taux de conversion de l’énergie important, ce qui favorise la bioaccumulation. De plus, ils ont une répartition importante dans les écosystèmes tropicaux et subtropicaux, ce qui rend la surveillance du Hg possible à large échelle. Mes travaux de doctorat s’intéressent aux quatre espèces de caïmans présents en Guyane (le caïman noir Melanosuchus niger, le caïman nain de Cuvier Paleosuchus palpebrosus, le caïman de Schneider Paleosuchus trigonatus et le caïman à lunettes Caiman crocodilus). J’ai travaillé sur les variations de Hg entre différents tissus obtenus par méthode de prélèvement peu invasif et, j’ai étudié l’influence de la morphologie et de l’écologie trophique (via les isotopes stables) des individus sur les concentrations en Hg. Ensuite, j’ai étudié l’impact d’une contamination en Hg sur les mécanismes physiologiques, le transfert maternel et ses effets sur les nouveau-nés
Mercury (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

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Vieira, Hugo Miguel Coelho da Silva. "Mercury bioaccumulation, human exposure, and fish consumption recommendations regarding mercury intake". Master's thesis, Universidade de Aveiro, 2015. http://hdl.handle.net/10773/14772.

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Mestrado em Biologia Marinha
Mercury (Hg) is classified as a pollutant of primary importance because of its high degree of toxicity, persistence and bioaccumulative properties, especially in the aquatic environment. It is released from natural and anthropogenic sources, and once in the environment, the inorganic Hg can be converted in to organic Hg (Methylmercury – MeHg) through bacterial processes. MeHg tends to bioaccumulate and biomagnify through the food web, representing a serious risk to human health. Due to the health risks of excessive Hg exposure, international agencies such as the USEPA (United States Environmental Protection Agency) have established safety levels (reference doses (RfD)) of daily exposure, being the Hg concentration present in human hair used to estimate MeHg exposure. Fish is an important component of a healthy diet for the human population and the fish consumption is expected to be relatively stable in the next two decades; however, fish is also considered a major source of MeHg exposure to human population. The key question of the present study was evaluating the Hg bioaccumulation in humans based in fish consumption. Specific tasks were delineated: (i) evaluatue the human exposure to Hg via fish consumption using a food frequency questionnaire, (ii) assess Hg exposure through Hg measurement in the hair, (iii) evaluate the Hg intake levels, through the application of formulas established by the World Health Organization, (iv) review fish consumption data, Mercury Tolerable intake values and Hg content in fish, based in several reports from Food and Agriculture Organization and European Union and (v) calculation and establishment of isocurves describing the maximum number of fishmeal per week without exceeding the MeHg Rfd (USEPA RfD), by combining number of meals (per week), amount of fish ingested (by meal) and levels of MeHg in fish. Overall data indicate that individuals consuming the highest number of fishmeals per week, also generally showed increased Hg levels in the scalp hair; however, the risk alert of the mercury exposure should not be considered. The real (quantified) and potential (extrapolated) Hg levels in human scalp of adolescents diverge as fish consumption increases, being the effective Hg uptake lower than the expected levels, emphasizing the ability of the human body to induce a self protection response, meaning that MeHg assimilation is probably minimized by detoxification mechanisms. As a final remark, considering the intake of Hg through fish consumption as the main route exposure, the study points out that even a small meal of 50g fish with 0.84 μg g-1 of MeHg per week would reach the USEPA RfD levels, despite the 1.0 μg g-1 of MeHg in fish are being allowed in fish consumption.
O Mercúrio (Hg) é classificado como um dos poluentes mais importantes devido ao seu alto grau de toxicidade, persistência e à sua capacidade de bioacumulação, especialmente no ambiente aquático. Este é libertado a partir de fontes naturais e antropogénicas, e uma vez no ambiente, o Hg inorgânico libertado pode ser convertido em Hg orgânico (metilmercúrio - MeHg) através de processos bacterianos. O MeHg tende a bioacumular e a biomagnificar ao longo da cadeia trófica, representando um sério risco para a saúde humana. Devido a estes riscos resultantes da exposição excessiva ao Hg, agências internacionais, como a USEPA (Agência de Proteção Ambiental dos Estados Unidos) estabeleceram níveis de segurança (doses de referência (DRf)) de exposição diária, sendo a concentração de Hg presente no cabelo humano utilizada para estimar esta exposição. O peixe é uma componente importante de uma dieta saudável para a população humana e o consumo de peixe deverá ser relativamente estável nas próximas duas décadas. No entanto, o peixe também é considerado uma das principais fontes de exposição a MeHg para a população humana. Este estudo teve como questão central a avaliação da bioacumulação de Hg em humanos face ao padrão de consumo de peixe, sendo delineados os seguintes objetivos específicos: (i) avaliar a exposição humana ao Hg face ao consumo de peixe utilizando um questionário de frequência alimentar, (ii) avaliar a exposição ao Hg através da quantificação de Hg no cabelo humano, (iii) avaliar os potenciais níveis de ingestão de Hg, através da aplicação de fórmula estabelecida pela Organização Mundial de Saúde, (iv) rever dados de consumo de peixe, valores de ingestão de Hg e conteúdo de Hg em peixes, com base em vários relatórios da Organização das Nações Unidas para a Alimentação e Agricultura, assim como, da União Europeia e (v) calcular linhas de tendência (isocurvas) descrevendo o número máximo de refeições de peixe por semana, sem exceder a DRf para o MeHg (USEPA DRf), combinando o número de refeições de peixe (por semana), a quantidade de peixe ingerido (por refeição) e a [MeHg] no peixe consumido. Os resultados revelam que os indivíduos que indicaram consumir um maior número de refeições de peixe por semana, também apresentam em regra níveis mais altos de Hg no cabelo; no entanto, o risco de alerta para a exposição ao Hg não deve ser considerado. Os níveis reais (quantificados) e valores potenciais (extrapolados) de Hg no cabelo dos adolescentes divergiram quando aumentou o consumo de peixe, sendo menor a absorção de Hg real comparativamente ao valor esperado, dando relevo à capacidade do corpo humano induzir uma resposta de auto-protecção, sendo a absorção de MeHg provavelmente minimizada por mecanismos de desintoxicação. O estudo salienta que mesmo uma pequena refeição de 50g de peixe com 0,84 μg g-1 de MeHg por semana alcançaria do valor estabelecido para a ingestão de MeHg (DRf USEPA), apesar de ser permitido o consumo de peixe com valores de 1,0 μg g-1 de MeHg.

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Lanceleur, Laurent. "L’argent : sources, transfert et bioaccumulation : cas du système fluvio-estuarien girondin". Thesis, Bordeaux 1, 2011. http://www.theses.fr/2011BOR14270/document.

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Les rejets d’argent (Ag) dans l’environnement liés à l’exploitation minière aux diverses applications industrielles (e.g. bijouterie, médecine, photographie, électronique et plus récemment les nanotechnologies) font de Ag un polluant historique et émergent, dont les transferts et les effets dans les milieux aquatiques sont largement sous-documentés. Ce travail présente un premier bilan des sources, du transfert et de la bioaccumulation de Ag dans le système fluvio-estuarien de la Gironde. Le continuum Lot-Garonne-Gironde, connu pour une pollution polymétallique (e.g. Cd, Zn) provenant du bassin de Decazeville, est un système modèle pour l’étude des transferts métalliques du continent à l’océan. Les enregistrements des signaux historiques (~50 ans) de Ag dans les sédiments du Lot en amont (Ag : 0,3 mg/kg) et en aval (Ag : jusqu’à 7 mg/kg) du bassin de Decazeville sont similaires à ceux de Cd, indiquant des sources et des processus de transport/dépôt communs liés à l’histoire minière et industrielle jusqu’en 1986. Le lessivage et l’érosion actuels des terrils provoquent localement des concentrations en Ag particulaire (AgP : 260 mg/kg) et dissous (AgD : 1260 ng/l) dans la rivière Riou-Mort qui sont 2 à 3 ordres de grandeur supérieures aux valeurs typiques. Malgré ces fortes concentrations, la contribution du Riou-Mort aux flux de Ag de la Garonne (AgD : 0,008 à 0,041 t/an ; AgP : 0,306 à 2,44 t/an ; 1999-2009) reste faible (AgP : <11% ; AgD : <6%). La Garonne transporte l’essentiel (63-83%) des apports en Ag à l’estuaire principalement sous forme particulaire (96±2%). La détermination du bruit de fond géochimique régional (AgP/ThP=0,026) a permis d’évaluer (i) la contribution naturelle (20% à 65%) aux flux totaux en AgP et (ii) les flux anthropiques spécifiques de AgP (15±10 g/km²/an et 0,24±0,16 g/hab/an) à l’échelle du bassin versant de la Garonne (La Réole). Dans l’estuaire salin, la désorption par les ions chlorures libère ~60% de AgP vers la colonne d’eau (addition), provoquant des concentrations maximales en AgD (6-8 ng/l) à salinité 15-25. La fraction en Ag désorbé correspond à la fraction potentiellement biodisponible ou réactive (i.e. extractible par HCl 1 M). Ainsi, les premières estimations des flux nets indiquent que l’export annuel de Ag vers le domaine côtier est à 50-80% lié à la phase dissoute (0,64 à 0,89 t/an en 2008 et 0,56 à 0,77 t/an en 2009). Bien que plus biodisponible sous forme ionique Ag+ (dominante en eau douce), l’accumulation de Ag dans les organismes estuariens (huîtres, crevettes et anguilles) reflète la pression d’exposition supérieure en eau saumâtre. L’exposition in situ d’anguilles européennes, espèce recommandée pour la biosurveillance du milieu dans le cadre de la Directive Cadre sur l’Eau, dans des cages à différents sites clé de l’estuaire pendant 3 mois, a mis en évidence les voies directes et trophiques de la contamination en Ag à des niveaux de contamination environnementaux. L’enregistrement historique de la contamination en Ag des huîtres de la Gironde (1979-2007, RNO, Ifremer) indique que le bassin de Decazeville a été la source majoritaire en Ag jusqu’en ~1988. Cependant, l’accumulation maximale de Ag dans ces bivalves après 1993 (de ~40 à plus de 100 mg/kg, poids sec) révèle une contribution croissante de sources additionnelles et contemporaines en Ag comme la photographie, l’ensemencement des nuages (30 à 63 kg/an) ou encore les rejets des eaux usées urbaines de Toulouse et de Bordeaux (42 et 57 kg/an). Ce travail constitue une base nécessaire à l’étude des rejets du cycle de Ag (y compris les nanoparticules) dans le milieu aquatique (quantification, transfert et toxicité) et des risques associés
Silver (Ag) emissions into the environment from former mining activities and various industrial applications (e.g. jewellery, medicine, photography, electronic products and more recently nanotechnology) make Ag both a historic and an emergent pollutant for which information on its transfer and toxicity in aquatic system are scarce. This work provides a first assessment of Ag sources, transfer and bioaccumulation in the Gironde fluvial-estuarine system. The Lot-Garonne-Gironde River continuum, known for its polymetallic pollution (e.g. Cd, Zn) derived from the Decazeville basin, is a model system for studies on metal transfer from watersheds to the ocean. The relationship between historical records (~50 years) of Ag concentrations in sediment cores from the Lot River, upstream (Ag: 0.3 mg/kg) and downstream (Ag: up to 7 mg/kg) of the Decazeville basin and those of Cd constitutes evidence of a common source and transport/settlement processes due to industrial activities until 1986. High particulate Ag (AgP: 260 mg/kg) and dissolved Ag (AgD: 1,260 ng/l) concentrations in the Riou-Mort River were attributed to current leaching and erosion of slag heaps by rainwater. Those concentrations were 2 to 3 orders of magnitude greater than typical values in the Gironde watershed. However, the Riou-Mort River contribution to the Garonne River Ag fluxes (AgD: 0.008-0.041 t/a; AgP: 0.306-2.44 t/an; 1999-2009) remained low (AgP: <11%; AgD: <6%). The Garonne River provided the quasi totality (63-83%) of Ag inputs to the estuary, mainly in its particulate form (96±2%). The regional geochemical background (AgP/ThP=0.026) was useful to estimate (i) the natural contribution (20-65%) to total AgP fluxes and (ii) the anthropogenic specific fluxes of AgP (15±10 g/km²/a and 0.24±0.16 g/hab/a) in the Garonne watershed (La Réole). In the estuarine salinity, chloro-complexation desorbed ~60% of AgP, causing maximalum AgD concentrations (6-8 ng/l) at salinity 15-25 (addition to the dissolved phase). This quantity was similar to the potentially bioavailable or reactive fraction (i.e. extracted by HCl 1 M). The first estimations of net fluxes suggested that 50-80% of the Ag annual export to the coast occurred in the dissolved phase (0.64-0.89 t/a in 2008 and 0.56-0.77 t/a in 2009). Even if the ionic form Ag+ (the main form in freshwater) is considered as the most bioavailable form, Ag accumulation in estuarine organisms (oysters, shrimps and eels) reflected the higher exposition pressure in brackish water. In-situ caging of European Eels (recommended species for the biosurvey of aquatic systems; European Water Framework Directive) in key sites of the Gironde Estuary during 3 months, highlighted the direct and trophic pathways of Ag contamination at the environmental level. The historical record of Ag contamination of the Gironde Estuary oysters (1979-2007, French Mussel Watch, RNO) indicated that the Decazeville basin was a major Ag source until ~1988. However, the maximum Ag accumulation in oysters after 1993 (from ~40 to more than 100 mg/kg, dry weight) suggested an increasing contribution of additional and contemporary Ag sources like photography, cloud seeding (30-63 kg/a) or Toulouse and Bordeaux wastewater effluents (42-57 kg/a). This work is a basis for future work on Ag (including nanoparticles) cycles and related risks in aquatic systems (quantification, transfer and toxicity)

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41

Moore, Bronwyn Ann. "Metal bioaccumulation and precious metal refinery wastewater treatment by phoma glomerata". Thesis, Rhodes University, 2008. http://hdl.handle.net/10962/d1009441.

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The biosorption of copper, nickel, gold and platinum from single metal aqueous solutions by the nickel hyperaccumulator Berkheya coddii plant biomass was investigated. Potentiometric titrations of the biomass and determination of optimal sorption pH for each metal showed that nickel ions were released from the biomass into solution. The presence of free nickel ions interfered with the uptake of the other three metals and further biosorption investigations were discontinued. Three fungal isolates found colonising metal solutions were cultured and screened for their ability to remove 50 mg.l⁻¹ of copper, nickel, gold and platinum from solution and to survive and grow in precious metal refinery wastewaters. One isolate was selected for further studies based on its superior metal uptake capabilities (35 and 39 mg.l⁻¹ of gold and platinum, respectively) and was identified as Phoma glomerata. Copper, nickel, gold and platinum uptake studies revealed that nickel and gold were the most toxic metal ions, however, toxicity was dependent on pH. At pH 6 more biomass growth was achieved than at lower pH values and metal uptake increased by 51 and 17 % for copper and nickel, respectively. In addition, the production of extracellular polymeric substances played a role in base metal interaction. Precious metals were observed to be preferentially removed from solution, complete removal of gold and platinum was observed at all initial pH values, 89 % of copper was bioaccumulated at an initial metal concentration of 55 mg.l⁻¹ (pH 6) and only 23 % of nickel was removed from solution under the same conditions. Metal bioaccumulation was confirmed through transmission electron microscopy and micro particle induced X-ray emission. The effect of P. glomerata immobilised in a packed bed reactor on precious metal refinery wastewaters was investigated. It was found that the fungal isolate was not able to remove the high salt and chemical oxygen demand concentrations found in the wastewaters, however due to its ability to survive and grow in undiluted wastewater and remove metal ions from solution it may be utilised as a metal detoxification step in the treatment process train.
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42

POMA, GIULIA. "Evaluation of bioaccumulation processes of brominated flame retardants in biotic matrices". Doctoral thesis, Università degli Studi di Milano-Bicocca, 2014. http://hdl.handle.net/10281/50902.

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The global reduction in the use of PBDEs and HBCD as flame retardants has opened the way for the introduction of “Novel” BFRs (NBFRs) in place of the banned formulations, indicating those BFRs that are new in the market or newly/recently observed in the environment in respect to PBDEs and HBCD. Consequently, consumption and production of these NBFRs will keep rising, and increasing environmental levels of these chemicals are expected in the near future. Important representatives of this group are decabromodiphenyl ethane (DBDPE), 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE), hexabromobenzene (HBB), and pentabromoethylbenzene (PBEB). In Italy, previous studies have shown that some BFRs (PBDEs) were measured at high concentrations in the Varese province due to the presence of a great number of textile and plastic industries, and particularly in the sediments of Lake Maggiore, where those facilities wastewaters are finally collected mainly through two lake tributaries (Bardello and Boesio). For these reasons, the present thesis has the aim to evaluate the presence, and the potential bioaccumulation and biomagnification processes of six different classes of BFRs (PBDEs, HBCD, DBDPE, BTBPE, HBB and PBEB) in the Lake Maggiore ecosystem, with particular regard to zebra mussels (Dreissena polymorpha), zooplankton, one littoral fish species (common roach - Rutilus rutilus), and two different pelagic species (twaite shad – Alosa agone and European whitefish – Coregonus lavaretus). Finally, the study has also considered the BFR contamination in the lake sediments with the aim of characterizing in detail the possible presence of temporal trends and/or identifying potential sources of contamination. Moreover, it is plausible that the BFR uptake by benthic organisms, followed by fish predation, might be a significant source of bioaccumulation.

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Manar, Rachid. "Effets populationnels du chlordane sur les microcrustacés cladocères Daphnia sp. dans une perspective d'évaluation des risques". Thesis, Metz, 2008. http://www.theses.fr/2008METZ031S/document.

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L'objectif général de ce travail est l étude de la toxicité chronique du chlordane chez un crustacé d eau douce afin d évaluer le risque de ce pesticide sur les organismes aquatiques. Pour ce faire, nous avons choisi le cladocère Daphnia magna comme modèle d étude, à cause de son rôle clé dans la chaîne trophique, sa sensibilité et son cycle de vie qui est mis à profit pour étendre le test de reproduction classique utilisant une seule génération saine sur deux générations successives. Le test chronique (21j) a donné une concentration sans effet observée (NOEC) sur tous les paramètres de 0,18 g/L qui constitue une donnée importante dans l évaluation du risque du chlordane pour le milieu aquatique. L exposition de D.magna aux fortes concentrations de chlordane a induit des malformations et l apparition de mâles chez la descendance. L étude de la bioaccumulation a montré le fort potentiel de bioaccumulation chez D.magna avec un facteur de bioaccumulation de 244000 (poids sec) après 40 jours d exposition à la NOEC. L étude de la toxicité du chlordane sur deux générations successives (F0 et F1) a montré que celle-ci augmente avec la concentration et le temps d exposition. Ainsi, la génération F1 est plus sensible que la génération F0 et la population de la génération F1 issue de la 5ème ponte s est montrée plus sensible que la génération F1 issue de la 2ème ponte. L étude de la capacité de récupération des daphnies de la génération F1, après leur transfert dans un milieu propre a montré l absence d une récupération totale aux plus fortes concentrations testées. La comparaison de la sensibilité de D.magna à un autre crustacé C.dubia suite à une exposition chronique au chlordane a souligné l intérêt de l utilisation de ce dernier dans l étude de la toxicité chronique des polluants persistants à condition de prolonger la durée du test de 7 à 14 jours. L ensemble de ces résultats souligne l intérêt du modèle D.magna dans l étude de la toxicité chronique des polluants persistants et de leurs éventuels effets sur les différents processus de reproduction
This research aimed at studying the toxicity of chlordane in freshwater crustacean in order to evaluate the risk of this pesticide on aquatic organisms. We choice Daphnia magna as model of study, because her key role in trophic chain, her sensitivity and her short life cycle that are exploited for extended the classic reproduction test using only one healthy generation on two successive generations. In the chronic test (21d), a concentration without observed effect (NOEC) on all parameters of 0.18 g/L was obtained. The exposition of D.magna to the strong concentrations of chlordane led the malformations and the apparition of males at the progeny. The study of the bioacumulation showed the high potential of bioaccumulation at D.magna with a factor of bioaccumulation of 244 000 (dry weight) after 40 days of exposition to the NOEC. The study of the toxicity of the chlordane on two successive generations (F0 and F1) showed that this one increases with the concentration and the time of exposition. So, the F1 generation is more sensitive than the F0 generation and the population of the F1 generation 5th brood is more sensitive than the one of the F1 generation 2nd brood. The study of the recovery of the daphnids after their transfer in clean water showed their capacity to restore reproduction only for the low doses. The comparison of the sensitivity of D.magna in another crustacean C.dubia following a chronic exposition to chlordane underlined the interest of the use of C.dubia in the study of the log term toxicity of the persistent pollutants under the condition to prolong the duration of the test from 7 to 14 days.The present work highlights the interest of our model in the study of the chronic toxicity of persistent pollutants and their possible effects on the different processes of reproduction

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44

Figures, Julie Elizabeth. "A study of the biochemistry of selected metals in the Clyde Estuary". Thesis, University of the West of Scotland, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360233.

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45

FLATAU, GILLES N. "Contribution a l'etude de la fixation du cadmiun par une bacterie marine". Nantes, 1989. http://www.theses.fr/1989NANT09VS.

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46

Mackenbach, Elizabeth M. "TENAX AS A MEASURE OF BIOAVAILABILITY AND REMEDIATION SUCCESS ON THE OTTAWA RIVER". OpenSIUC, 2013. https://opensiuc.lib.siu.edu/theses/1125.

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Traditional assessments of contaminated sites require the collection and analysis of field media. Specifically, sediment analysis is used to determine type of contaminant as well as total contaminant concentrations (TCC). Although TCC can be used to determine if a site is contaminated, it is unable to adequately predict exposure and bioaccumulation in organisms. Biota-sediment accumulation factors were originally introduced to calculate and predict expected exposure to organisms based on sediment TCC. As they have been shown to be unreliable with field sediments, their use is limited. Alternatively, Tenax has been examined as a tool for measuring exposure to hydrophobic organic contaminants, where the Tenax extractable concentration is related to the bioaccumulated organism concentration. Although this relationship has been demonstrated in multiple studies, few have actually related the data from multiple sites to develop a standard model of Tenax accumulation. This research had two specific goals: Develop a literature based model of Tenax accumulation of polychlorinated biphenyl congeners (PCBs) and test it's applicability to field collected sediments from the Ottawa River (OR, Toledo OH, Chapter 2) and verify the use of the model in a highly-disturbed, post-dredge system, as well as the use of Tenax as an indicator of changes in bioavailability after dredging (Chapter 3). The literature-based complete Tenax model (TM) provided a strong model for the prediction of bioaccumulation in Lumbriculus variegatus (r2=0.91). When compared to the pre-dredge data from the OR, 95% of the data were encompassed by the CTM. No bias of the model was observed across homologue groups. Subsequently, the model was used with sediments collected after remediation via dredging from the OR. In this study, the CTM encompassed 73% of the data. Although all sites along the river were considered disturbed by the dredging, resuspension, and drift of sediments, data from sites that were less disturbed were better described by the model (86% versus 64% of dredged data). Overall, the CTM is recommended for use in the prediction of exposure and accumulation of PCBs in field sediments.

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47

Harris, Craig S. "Bioaccumulation of zinc in periphyton and invertebrates, lotic field and microcosm studies". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ51353.pdf.

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Monrreal, Robert Horvath. "Hydrology and water chemistry in Weeks Bay, Alabama implications for mercury bioaccumulation /". Auburn, Ala., 2007. http://repo.lib.auburn.edu/2007%20Spring%20Theses/MONRREAL_ROBERT_35.pdf.

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49

Cross, Richard Kynaston. "The fate of engineered nanomaterials in sediments and their route to bioaccumulation". Thesis, University of Exeter, 2017. http://hdl.handle.net/10871/32761.

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The production of engineered nanomaterials is an emerging and rapidly expanding industry. It exploits the capacity for materials to be manufactured to present particular properties distinct from the bulk material, through tailoring of the particle size and surface functionality. This ability to fine tune particle properties at the nanoscale is responsible for the explosion in uses of engineered nanomaterials in industries as diverse as cosmetics and medicine, to “green” technologies and manufacturing. However, this increased reactivity at the nanoscale, defined as having at least one dimension < 100 nm in size, is also responsible for the increasing concern over their environmental safety. Material flows of engineered nanoparticles into the aquatic environment have been identified throughout their production, use and disposal, putting these ecosystems at potential risk of contamination. In particular, sediments are a likely sink of engineered nanomaterials in the aquatic environment due to their propensity to destabilise and settle out of suspension in natural freshwaters. An emerging body of literature has demonstrated toxicity of nanomaterials to aquatic species. In this thesis, the case is presented for using bioaccumulation as a first indicator of risk to aquatic organisms exposed to engineered nanomaterials. Using the sediment dwelling freshwater worm, Lumbriculus variegatus, this work investigates the factors which govern the bioaccumulation of cerium oxide and silver nanomaterials. It is hypothesised that the fate of these materials in sediments will be determined by their core composition, primary particle size and surface coating. A novel approach is presented to measure two biologically relevant fate parameters (persistence of particles and dissolved species in the sediment pore waters) and how particle properties affect the distribution of the nanomaterials between these phases of the sediment. This provides the context within which to interpret biological exposures assessing both the extent of uptake and how they are accumulated, whether through dietary uptake or across the skin. Understanding this route to uptake is important as the mechanism of toxicity may depend upon the point of contact of a material at the nano-bio interface. For example, a nanoparticle which comes into contact with biological material in the gut may exert a different effect upon an organism than one which is translocated directly across the skin. It is demonstrated that sediment properties determine the fate of engineered nano cerium oxide and silver to a greater extent than stabilising surfactants, with the majority of particles aggregating or associating with the solid constituents of the sediment > 200 nm in size. The dissolved fraction of the metal present in the pore waters was a better predictor of bioavailability than the persistence of particulate material < 200 nm in size, with partially soluble nanosilver being more available than insoluble cerium oxide. The route to metal nanoparticle uptake also differed with particle core, with electrostatically stabilised citrate and sterically stabilised polyethylene glycol (PEG) coated ceria available only through dietary uptake, whilst citrate and PEG coated silver was accumulated through transdermal uptake. Dynamic changes in the fate of silver nanoparticles were also observed for sterically stabilised polyvinylpyrrolidone (PVP) coated silver, resulting in the emergence of a colloidal pore water fraction of silver after 3 months aging in sediments. However, this colloidal silver was still not considered accumulated, indicating that low molecular weight species of silver, dissolving from the particle surface either during the exposure or upon contact with the worms’ surfaces was responsible for uptake of silver from the sediments. In conclusion, this work contributes towards our understanding of the factors which determine both the route and extent of biological uptake of engineered nanomaterials. It presents a novel combination of methods which allow for understanding bioaccumulation of these materials in the context of their fate and behaviour within sediments.

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Ben, Amor Hela. "Etude et optimisation de bioaccumulation de Mg2+ dans les microalgues « Chlorella vulgaris »". Thesis, Université Paris-Saclay (ComUE), 2015. http://www.theses.fr/2015SACLC004/document.

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Des cultures de Chlorella vulgaris ont été réalisées en triplicata sur de longues périodes (15-30 jours) en autotrophie et en mixotrophie afin d’étudier l’effet de Mg2+ sur les microalgues et déterminer sa concentration dans la biomasse au cours de la croissance. Différentes concentrations ont été testées (de 8.9 à 465 mg L-1). Ceci a montré que le Mg2+ n’est pas toxique pour les algues à des concentrations élevées provoquant habituellement l’inhibition de la croissance dans le cas d’autres ions divalents (métaux lourds). Des bilans matière ont été établis et vérifiés avec une précision satisfaisante (écart moyen de 90%). La quantité de Mg2+ bioaccumulée augmente avec la concentration initiale de Mg2+ du milieu de culture. Une saturation en Mg2+ intracellulaire a été observée à partir d’environ 45 mg de Mg2+ L-1. Typiquement, la répartition entre le Mg2+ extracellulaire et intracellulaire est de 18% contre 51% dans le bioréacteur (5L) pour une concentration initiale de 16 mg L-1. En mixotrophie (addition de 10 g L-1 de glucose), une production de biomasse significativement plus importante et plus rapide que celle en autotrophie a été observée. En revanche, la quantité de Mg2+ accumulée dans les cellules est plus importante en autotrophie qu’en mixotrophie. Des mesures de chlorophylle a, de nitrate et de glucose ont été également réalisées. Afin de comprendre la cinétique relativement complexe de bioaccumulation du Mg2+, un modèle cinétique original a été élaboré couplant transfert (externe, membrane, interne) et réactions (ad/absorption) en milieu hétérogène. Le modèle a été validé expérimentalement. Il permet de rendre compte au mieux de l’ensemble des résultats obtenus
Chlorella vulgaris cultures were grown in triplicate over 15-30 days under autotrophic or mixotrophic conditions in order to study Mg2+ uptake and accumulation into the biomass. The concentrations of Mg2+ tested were 8.9 to 465 mg L-1. The results showed that Mg2+ is not toxic to C. vulgaris even at 465 mg L-1 which is not the case for other divalent ions (especially heavy metals). The mass balances for Mg2+ accumulation were determined for the cultures and were confirmed to an average of 90%. Beyond 46.1 mg of Mg2+ L-1 in the culture medium, the cells became saturated at 4 mg of Mg2+ absorbed per g of dry biomass. In the bioreactor (5L), at an initial Mg2+ concentration of 16 mg L-1, the cells accumulated 69% of the initial concentration, in which 18% was adsorbed and 51% absorbed. The chlorophyll a, nitrate and glucose concentrations were measured during the experiments. Under mixotrophic conditions (glucose 10 g L-1), a greater and faster biomass production was obtained than under autotrophic conditions. The Mg2+ bioaccumulation was higher in the autotrophic rather than the mixotrophic phase. In order to understand the kinetics of Mg2+ uptake, an original kinetic model was developed coupling the transfer and reaction phenomena in heterogeneous media. This model was confirmed experimentally

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