Aquaculture is the fastest growing food industry in the world and it accounts for roughly half of the world's fish supply. The majority of global aquaculture production occurs in freshwater systems that are increasingly subject to multiple uses by different stakeholders. Given the overall scarcity of freshwater on a global scale, freshwater aquaculture will face increasing environmental constraints that will demand an ever better understanding of its potential impacts on the aquatic environment and human health. This thesis consists of a series of studies that, collectively, contribute to further our understanding on the effects of freshwater aquaculture effluents on aquatic ecosystems, on the effects and environmental safety of antibiotics used in freshwater aquaculture on aquatic bacterial communities and on the link between antibiotic pollution and antibiotic resistance. Chapter 2 reviews the effects of freshwater aquaculture effluents on stream ecosystems using land-based salmonid farms as a case study. In this chapter I discuss relevant considerations related to the temporal and spatial scales of effluent discharge and ecological effects that highlight the need to characterize the patterns of stressor discharge when assessing environmental impacts and designing ecological effects studies. I also discuss the potential role of multiple stressors - with an emphasis on veterinary medicines - in disrupting ecosystem structure and function. Overall, the critical analysis presented in this chapter indicates that further research on the effects of veterinary medicines using relevant exposure scenarios would significantly contribute to our understanding of their impact in relation to other effluent stressors. Chapter 3 is a general methods chapter that describes the stream microcosm system used to assess the effects of erythromycin thiocyanate (ERT) and florfenicol (FFC) on bacterial communities of stream biofilms. This chapter presents the results of preliminary experiments whose results provided relevant information on the overall operation of the microcosms and on the variability of major physical and biological variables. This information guided the experimental designs used to assess the effects of FFC and ERT on the bacterial community structure of stream biofilms. Chapter 4 presents the results of the experiment conducted to assess the effects of FFC on the bacterial community structure of developing biofilms. The objective was to assess changes in bacterial community structure along a gradient of FFC concentrations that could provide insight into the type and magnitude of effects that could be expected from episodic exposure of stream biofilms to FFC in headwater streams. At 10 and 20 days of biofilm development, bacterial community structure differentiated in a pattern consistent with the FFC concentration gradient and there was a positive relationship between bacterial richness and bacterial diversity with FFC concentration. At 15 days of biofilm development there was also a positive relationship between FFC concentration and the surface coverage of bacteria and extracellular polymeric substances. These trends declined as the biofilm developed a more complex architecture, in terms of thickness and in the surface coverage of algae. The results are consistent with an initial stimulatory effect of FFC on biofilm formation that triggered changes in bacterial community structure that were gradually compressed as the development of a complex biofilm architecture increased the relative importance of autogenic ecological processes. The results suggest that the co-occurrence of FFC with bacterial pathogens in effluents and wastewaters may favour their persistence in the environment by enhancing biofilm formation. Chapter 5 presents the results of the experiment conducted to assess the effects of ERT on the bacterial community structure of developing biofilms. Currently, Aquamycin® 100 - a Type A medicated article (i.e., Premix) containing 100 g ERT lb-1 and used to produce a Type C medicated feed - is a candidate drug for approval by the US FDA to control mortality associated with bacterial kidney disease in freshwater salmonids. The objective of this experiment was to assess the effects of ERT on the bacterial community structure of stream biofilms using an exposure period consistent with the 28-day treatment regime suggested for Aquamycin® 100. The results provide no evidence to suggest that a 30-day exposure to ERT concentrations in the range of 10 μg L-1 (i.e., 7.3 ± 3.9 μg L-1) would lead to changes in the bacterial community structure or overall bacterial abundance of stream biofilms, while they suggest that these effects may occur at concentrations in the range of 100 μg L-1 (i.e., 87.2 ± 31.1 μg L-1). Chapter 6 attempts to determine whether environmental concentrations of antibiotics and concentrations representing action limits used in environmental risk assessment may exert a selective pressure on clinically relevant bacteria in the environment. In this chapter I use bacterial inhibition as an assessment endpoint to link antibiotic selective pressures to the prevalence of resistance in bacterial populations. Species sensitivity distributions were derived for three antibiotics by fitting log-logistic models to endpoints calculated from minimum inhibitory concentration (MIC) distributions based on worldwide data collated by the European Committee on Antimicrobial Susceptibility Testing (EUCAST). Bacteria represented in these distributions were placed in a broader context by performing a brief phylogenetic analysis. The potentially affected fraction of bacterial genera at measured environmental concentrations of antibiotics and environmental risk assessment action limits was used as a proxy for antibiotic selective pressure. Measured environmental concentrations and environmental risk assessment action limits were also directly compared to wild-type cut-off values. Results suggest that measured environmental concentrations of antibiotics and concentrations representing environmental risk assessment action limits are high enough to exert a selective pressure on clinically relevant bacteria that may lead to an increase in the prevalence of resistance. Chapter 7 presents the results of an exploratory analysis conducted to assess the abundance of class 1 integrons in stream biofilms exposed to FFC and ERT. There was no pattern in the abundance of intI1 genes consistent with the treatment of FFC and ERT, suggesting either the absence of gene cassettes involved in dealing with selective pressures caused by these antibiotics or that the concentrations tested were below those required to give them a selective advantage. Chapter 8 is a brief general discussion that brings together the findings of the thesis and makes suggestions for future research. Key areas identified for future research include assessing in further detail the stimulatory effect of FFC on biofilm formation in complex bacterial communities, the interactive effects of multiple aquaculture effluent stressors on aquatic bacterial communities and their potential effects on the development of antibiotic resistance, the fate of FFC and ERT in stream ecosystems, and further developing the analysis based on MIC distributions presented in chapter 6 to assess the potential effects of antibiotic pollution on the selection of multi-drug resistance in the environment.

For business organizations the concept of risk has always been important. Lately, this importance has been enhanced due to a number of corporate and societal circumstances. New and previously unconsidered risks are gaining increased significance in the overall risk management of many companies. This doctoral thesis takes a wide approach and examines factors relating to the evolving area of operational risk management. It focuses on risks that concern firms’ operations rather than merely financial risk exposures. The thesis consists of four empirical studies that address diverse but interrelated aspects of operational risk in Swedish industry settings. Building on four sets of independent data collections, they apply both quantitative and qualitative methods. The thesis reports results of operational risk management regarding organizational aspects, perceived challenges, the regulative environment, current societal and business trends, and various stakeholders. Issues like trust, risk perception, risk communication, corporate value, reputation, and brand value are also discussed. On the whole, the empirical findings indicate that a new risk paradigm has emerged. As society has boosted the management of various risks as a corporate responsibility, the costs of failing to manage such risks have increased substantially. / Diss. Stockholm : Handelshögskolan, 2009 Sammanfattning jämte 4 uppsatser

Univ., Diss.--Hamburg, 2005. / Zsfassung in dt. Sprache.

In the West African country Ghana, which has a history of poor natural resource management, discovery of offshore petroleum resources in 2007 and subsequent commercial production in 2010 (with British multinational Tullow Oil as lead operator) is a potential source of potential wealth and inequality. Using the Cultural Theory of Risk, Social Amplification of Risk Framework, and the Corporate Sustainability Framework — a proposed model—as theoretical foundations, this dissertation examines corporate sustainability practices, communication, and their implications for local residents’ risk perceptions, corporate reputation, and risk management. The study also assesses how cultural worldviews and informational networks (e.g., an environmental group, opinion leaders, and media) amplify or attenuate residents’ risks perceptions. Data were collected via interviews with key actors including a non-governmental organization (NGO), a survey of a representative sample of Half Assini residents in one of the six coastal districts that adjoin Ghana’s offshore petroleum region, and analyses of Tullow’s corporate social responsibility (CSR) reports and other communication texts. Extant worldview and corporate reputation measures were also developed/adapted and tested. The study finds support for the view that cultural worldview and affect are associated with public risk perceptions. Thus, individuals who (a) do not subscribe to the worldview that government ought to regulate corporate behaviors, (b) show a relatively high sense of attachment to their communities, (c) rate the images associated with Ghana’s offshore oil production favorably, and (d) rate the images associated with Tullow Oil positively are more likely to be worried that Ghana’s offshore oil production poses significant risks for the country and their local communities. Regarding corporate sustainability communication, the study observes that Tullow uses a predominantly technical, expert-driven approach, which seeks to discursively position it as an aspirational, engaged, and responsible organization. While critiquing Tullow’s corporate sustainability and communication approach, the research also argues that corporate sustainability (CSR and risk) communication has the potential to constitute desirable corporate practices and could ultimately culminate in meaningful social change. Theoretical contributions to risk perception, risk management/communication, corporate reputation, and CSR communication are discussed. Practical implications for advocacy, corporate practices, and public participation in environmental decision-making are discussed.

No Estado do Rio de Janeiro, a atividade de transporte rodoviário de produtos perigosos foi responsável por aproximadamente 40% dos atendimentos a emergências realizados pela FEEMA (hoje INEA) nos últimos anos. Dentre as diversas rotas de tráfego desses produtos, destaca-se a rodovia Presidente Dutra que percorre as imediações dos rios Paraíba do Sul e Guandu, e seus principais afluentes. A exposição a riscos ambientais da ETA Guandu é, portanto, bastante alta, pois compreende a Bacia do rio Paraíba do Sul, a montante da transposição, bem como a Bacia do rio Guandu, a montante do ponto de captação da Cedae (área de influência da ETA Guandu). Este trabalho identifica riscos de acidentes ambientais associados ao transporte terrestre de produtos perigosos em parte da área territorial de influência da ETA Guandu, buscando fornecer subsídios para a elaboração de um plano de contingência das Bacias dos rios Paraíba do sul e Guandu. A ETA Guandu, que abastece cerca de 9 milhões de habitantes da RMRJ, capta águas do rio Guandu que, por sua vez, depende principalmente das águas transpostas do rio Paraíba do Sul e do rio Piraí, situados em outra bacia hidrográfica. Além de um mapeamento de pontos de alta e média gravidade das principais rodovias e ferrovias na área de influência da ETA Guandu, a principal contribuição deste estudo foi a identificação de vários trechos de alto risco de acidentes ambientais ao longo da rodovia Presidente Dutra, em território fluminense, que podem efetivamente comprometer a qualidade das águas dos rios Paraíba do Sul e Guandu. / In the State of Rio de Janeiro, roadway transportation of hazardous products was responsible for approximately 40% of emergency attendances by FEEMA (hereafter INEA) in the last past years. From the diverse traffic routes, the Roadway Presidente Dutra, that runs the adjacencies of Paraíba do Sul River and its affluents, comes away. The environmental risks exposition from Guandu ETA is, therefore, quite high, since it comprises the Paraíba do Sul River Basin, upwards its transposition, and Guandu River Basin, upwards CEDAE water collection point (Area of influence of Guandu ETA). This essay identifies environmental accident risks associated to hazardous products roadway transportation in part of the Guandu ETA influence area, trying to offer assistance on the contingency plan elaboration for the Paraíba do Sul and Guandu Basins. The Guandu ETA, that supplies water do 9 million inhabitants of Rio de Janeiro Municipality, collects water from Guandu River, which depends on the transposed waters from Paraíba do Sul and Piraí Rivers, located in another basin. Besides mapping points of high or medium gravity of the main roadways and railroads in the area of influence of the Guandu ETA, the main contribution of this study was to identify several excerpts with high risk of environmental accidents along Presidente Dutra roadway, in Rio de Janeiro State territory, that may impact water qualities of Paraíba do Sul and Guandu rivers.

No Estado do Rio de Janeiro, a atividade de transporte rodoviário de produtos perigosos foi responsável por aproximadamente 40% dos atendimentos a emergências realizados pela FEEMA (hoje INEA) nos últimos anos. Dentre as diversas rotas de tráfego desses produtos, destaca-se a rodovia Presidente Dutra que percorre as imediações dos rios Paraíba do Sul e Guandu, e seus principais afluentes. A exposição a riscos ambientais da ETA Guandu é, portanto, bastante alta, pois compreende a Bacia do rio Paraíba do Sul, a montante da transposição, bem como a Bacia do rio Guandu, a montante do ponto de captação da Cedae (área de influência da ETA Guandu). Este trabalho identifica riscos de acidentes ambientais associados ao transporte terrestre de produtos perigosos em parte da área territorial de influência da ETA Guandu, buscando fornecer subsídios para a elaboração de um plano de contingência das Bacias dos rios Paraíba do sul e Guandu. A ETA Guandu, que abastece cerca de 9 milhões de habitantes da RMRJ, capta águas do rio Guandu que, por sua vez, depende principalmente das águas transpostas do rio Paraíba do Sul e do rio Piraí, situados em outra bacia hidrográfica. Além de um mapeamento de pontos de alta e média gravidade das principais rodovias e ferrovias na área de influência da ETA Guandu, a principal contribuição deste estudo foi a identificação de vários trechos de alto risco de acidentes ambientais ao longo da rodovia Presidente Dutra, em território fluminense, que podem efetivamente comprometer a qualidade das águas dos rios Paraíba do Sul e Guandu. / In the State of Rio de Janeiro, roadway transportation of hazardous products was responsible for approximately 40% of emergency attendances by FEEMA (hereafter INEA) in the last past years. From the diverse traffic routes, the Roadway Presidente Dutra, that runs the adjacencies of Paraíba do Sul River and its affluents, comes away. The environmental risks exposition from Guandu ETA is, therefore, quite high, since it comprises the Paraíba do Sul River Basin, upwards its transposition, and Guandu River Basin, upwards CEDAE water collection point (Area of influence of Guandu ETA). This essay identifies environmental accident risks associated to hazardous products roadway transportation in part of the Guandu ETA influence area, trying to offer assistance on the contingency plan elaboration for the Paraíba do Sul and Guandu Basins. The Guandu ETA, that supplies water do 9 million inhabitants of Rio de Janeiro Municipality, collects water from Guandu River, which depends on the transposed waters from Paraíba do Sul and Piraí Rivers, located in another basin. Besides mapping points of high or medium gravity of the main roadways and railroads in the area of influence of the Guandu ETA, the main contribution of this study was to identify several excerpts with high risk of environmental accidents along Presidente Dutra roadway, in Rio de Janeiro State territory, that may impact water qualities of Paraíba do Sul and Guandu rivers.

Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Filosofia e Ciencias Humanas / Made available in DSpace on 2018-08-15T21:24:43Z (GMT). No. of bitstreams: 1 Silva_CesarAugustoMarquesda_M.pdf: 4288587 bytes, checksum: 7047af8acde22f0055c700f95c46522f (MD5) Previous issue date: 2010 / Resumo: Durante as últimas décadas a demografia discutiu importantes conceitos ao tratar da relação entre dinâmica populacional e mudança ambiental. Surgiram novos caminhos, buscando compreender essa relação em análises centradas no entendimento do papel do espaço, dos padrões de produção e consumo, do risco e da vulnerabilidade. Recentemente, com a confirmação das estimativas das mudanças climáticas, a demografia é novamente desafiada a elucidar os elementos da dinâmica populacional que afetam o clima e que por ela são afetados. Nessa pesquisa objetiva-se compreender elementos desse segundo ponto, analisando riscos ambientais às mudanças climáticas em populações residentes em zonas costeiras. Mais especificamente, analisamos a dinâmica de três municípios costeiros do Estado de São Paulo, na Região Metropolitana da Baixada Santista: Bertioga, Guarujá e São Vicente. Tais municípios, majoritariamente urbanos, abrigam espaços diferenciados e desiguais, tanto do ponto de vista geográfico como social. Geograficamente, a presença de morros, rios, estuários e do próprio mar, condicionam a formação de riscos ambientais diferenciados. Socialmente, com a ocupação dos espaços para usos diversos (residenciais, turísticos e industriais), e por grupos com perfis sócio-econômicos particulares, cada um desses riscos atinge populações também específicas. A partir desses fatores a hipótese do trabalho é que populações com características distintas passam por diferentes riscos ambientais. Desse modo, os riscos que selecionamos são relativos às mudanças ambientais: a elevação do nível do mar, as inundações e os deslizamentos. Para cada um desses riscos, e de suas possíveis combinações, foram criadas zonas de risco, utilizando os dados de setores censitários. Os resultados indicaram a confirmação da nossa hipótese: populações mais pobres estão nas imediações de corpos d'água e morros, áreas onde a possibilidade das intensificações de inundações e deslizamentos é maior, enquanto as mais ricas localizam-se próximas ao mar, onde o maior risco é o da elevação do nível médio do mar / Abstract: Demography has discussed important concepts in concern with the relation between population dynamics and environmental change through last decades. New ways were developed and the role of space, patterns of production and consumption, risk and vulnerability were incorporated in theses analysis. Recently, with more accuracy estimates of climate change, demography is again challenged to elucidate the elements of population dynamics that affect climate and vice-versa. This research aims to understand this elements, analyzing risks of climate change on populations living in coastal areas. More specifically, we analyze the dynamics of three coastal municipalities of Sao Paulo State, in the Metropolitan Area of Baixada Santista: Bertioga, Guarujá and São Vicente. These municipalities, mostly urban, harbor differentiated and uneven spaces, both geographically and socially. Geographically, the presence of hills, rivers, estuaries and the sea, influence different environmental risks. Socially, space has been transformed according to several social uses (residential, tourist and industrial), resulting in specific groups, with particular socio-economic profiles, living in distinct risks zones. Based on these factors, the hypothesis adopted is that populations with different characteristics are replaced by different environmental risks. Therefore, the risks selected represent some of the environmental changes dangers: rising sea levels, more intensive flooding and landslides. For each of these risks, and their possible combinations were created risk areas, using data from census tracts. The results indicated the poorest are in the vicinity of ponds and hills, where the possibility of intensification of floods and landslides is higher, while the richest are sited near sea, where the greatest risk is the elevation of the average sea level / Mestrado / Demografia / Mestre em Demografia

O propósito do princípio da precaução é evitar danos irreversíveis ao meio ambiente e à saúde humana ao permitir a ação preventiva, mesmo na ausência de certeza científica sobre as causas ou conseqüências de determinada atividade. A precaução é uma resposta às novas tecnologias e aos fenômenos que podem provocar impactos irreparáveis e incomensuráveis e que, portanto, precisam ser revistos pela comunidade internacional, Estados e indivíduos. Significa, também, envolver a participação popular nas decisões sobre quais riscos são aceitáveis em determinada sociedade e quais devem ser evitados. A base sociológica sob a qual está baseado o trabalho é a teoria de Ulrich Beck sobre a sociedade de risco global. O princípio da precaução é analisado sob os prismas dogmático e funcional: as principais características do princípio são apresentadas, bem como as críticas ao instituto; também são expostas as funções do princípio da precaução, sua eficácia social e status jurídico. A fim de explicar as dificuldades que circundam o tema dos princípios do direito internacional do meio ambiente, as principais teorias dos princípios são analisadas, concluindo-se que os princípios do DIMA necessitam de uma teoria própria. Na última parte, o trabalho procura demonstrar como o princípio da precaução pode ser operacionalizado através do fortalecimento institucional, sobretudo da Convenção-Quadro das Nações Unidas sobre Mudança do Clima. O tema das mudanças climáticas é paradigmático, já que exige ação internacional preventiva a fim de evitar os impactos do aquecimento global, mesmo face à inexistência de consenso científico sobre as causas e consequências desse fenômeno. Ao permitir maior participação democrática e abrir espaço para que a percepção pública sobre os riscos possa refletir em decisões jurídico-políticas, o arranjo institucional criado pela Convenção permite, ainda que com algumas falhas, uma discussão maior sobre os desafios que circundam o tema. Considerando os fundamentos da teoria de Beck sobre a modernização reflexiva, a origem política dos riscos e a democratização das discussões sobre eles, o papel da subpolítica na sociedade atual e a irreversibilidade de catástrofes ambientais, conclui-se que o princípio da precaução é indispensável ao direito e à política ao inserir a responsabilização a priori dos possíveis danos e a participação social nas decisões futuras / The purpose of the precautionary principle is to avoid irreversible damage to the environment and human health by allowing preventive action, even in the absence of scientific certainty regarding the causes or consequences of certain activity. Precaution is an answer to new technologies and phenomena that may promote irreparable and incommensurable impacts and, therefore, need to be reviewed beforehand by the international community, states and individuals. Furthermore, it nurtures popular participation in decision-making regarding what risks are acceptable in a given society and what risks should be avoided. The sociological foundation of this work is Ulrich Becks world risk society. The precautionary principle is analysed under the dogmatic and functional viewpoints: the principles main characteristics and critiques are presented, and I also explore the precautionary principles functions, social efficacy, and legal status. In order to explain the difficulties pertaining to the subject of international environmental law, this thesis analyzes the main theories on legal principles, and concludes that a more suitable theory for international environmental law principles is needed. In the last part, this work demonstrates how the precautionary principle can be operationalized through institutional strengthening, especially of the United Nations Framework Convention on Climate Change. Climate change is a paradigmatic case, since it demands international preventive action in order to avoid the impacts of global warming, even in the absence of scientific consensus regarding its causes and consequences. By allowing greater democratic participation and by creating space for communication so that public perception can be reflected in legal and political decisions, the institutional arrangement created by the Convention allows for, if imperfectly, a wider discussion about the challenges of climate change. Considering the foundations of Becks theory about reflexive modernization, the political origin of risks and the democratization of discussions on risks, the role of subpolitics in modern society and irreversibility of environmental catastrophes, this work concludes that the precautionary principle is indispensable to law and politics by adding a priori responsibility of possible damages and social participation in future decisions.

A presente tese tem como pano de fundo a crescente preocupação com os impactos das alterações no meio ambiente global e objetiva a análise da dimensão humana dessas mudanças, que emergem do cenário de insegurança, riscos e incertezas acentuado com o recente debate internacional sobre mudanças climáticas. A ocorrência cada vez mais frequente de desastres ambientais e a progressiva degradação de recursos ambientais essenciais, comprometendo gravemente a vida e a segurança de indivíduos, grupos e comunidades inteiras em todo o mundo, a ponto de inviabilizar a sobrevivência em seus locais de origem, ensejam novas situações jurídicas que precisam ser reguladas pelo Direito Internacional. Nesse contexto, dois pontos centrais conduzem o presente estudo: a emergência de uma nova categoria de pessoas na ordem internacional e a ausência de proteção jurídica pelos instrumentos internacionais vigentes. As dificuldades em torno do consenso sobre uma definição jurídica e a natureza do regime de proteção, tomando-se como base as normas vigentes de Direito Internacional dos Refugiados, de Direito Internacional dos Direitos Humanos e do Direito Internacional do Meio Ambiente, deixam à mostra as limitações do Direito Internacional Público atual para conferir um tratamento adequado à complexidade do problema em questão. Nesse sentido, uma resposta internacional adequada exige, de um lado, o reconhecimento do status jurídico próprio para a nova categoria; de outro, a construção de estratégias de prevenção e combate das múltiplas causas que forçam os deslocamentos. Para suprir a lacuna normativa existente propõe-se uma abordagem integrada, identificando elementos importantes nos regimes internacionais que possam contribuir para a construção de um compromisso global inovador e compatível com a nova dinâmica internacional. / This thesis has as its background the growing concern about the impacts of global environmental changes and aims the analysis of the human dimension of these changes, which emerge from the scenario of insecurity, risks and uncertainties highlighted with the recent international debate on climate change. The increasingly frequent occurrence of environmental disasters and a gradual deterioration of essential environmental resources, severely compromising the lives and safety of individuals, groups and entire communities around the world as to render them unfit for survival in their homes, create new legal situations which need to be regulated by International Law. In this context, two central points lead this study: the emergence of a new category of people in the international order and the absence of legal protection by the international instruments in force. The difficulties surrounding the consensus on a legal definition and nature of the regime of protection, taking as basis the standards of International Refugee Law, International Law of Human Rights and International Law on the Environment show the limitations of current Public International Law to give a proper treatment of the complexity of the problem. Accordingly, an appropriate international response requires on the one hand, recognition of a special legal status to the new category, and second, the construction of strategies to prevent and combat the multiple causes that force displacements. To fill the existing normative gap, we propose an integrated approach, identifying important elements in the international regimes that can contribute to building an innovative global compromise, compatible with the new international dynamics.

[...] L’objectif decette thèse est l’étude des mécanismes modulant la biodisponibilité des métaux pour l’escargotCantareus aspersus (syn. Helix aspersa), invertébré vivant à l’interface sol‐plante‐air (maillonintermédiaire, saprophage, phytophage, de chaînes alimentaires). La biodisponibilité est principalementévaluée ici en mesurant l’accumulation (concentrations internes en métaux après 28 jours d’exposition) etles flux d’assimilation. L’influence de paramètres édaphiques sur la disponibilité et la biodisponibilité desmétaux des sols et la contribution des sources de contamination (sols/plantes) des escargots constituentles variables étudiées dans deux conditions d'exposition :[...] L’ensemble des résultats souligne la nécessité de prendre en compte les facteurs et lesmécanismes qui modulent la biodisponibilité des métaux pour modéliser au mieux leur accumulation etleur assimilation par les escargots. Aucune méthode chimique unique d’estimation de la biodisponibilitédes métaux n’ayant pu être déterminée, nous préconisons l’utilisation de mesures biologiques quireflètent mieux la réelle biodisponibilité. / [...] The aim of this thesis is to study the mechanisms that modulate metal bioavailabilityfor the garden snail Cantareus aspersus (= Helix aspersa) a soil invertebrate living at the interfacesoil‐plant‐air (saprophagous and phytophagous intermediate link in the food chain).[...] These data underline the necessity to take into account the factors and mechanisms that modulate themetal bioavailability for snails to better model accumulation and assimilation of metal by snails. As nounique chemical method to assess metal bioavailability was determined, we recommend the use ofbiological measures that identify the real metal bioavailability rather than the use of chemical measures.