CR26-AgroEcoSystem-2 - You will join the Sol&Tox team within the EcoSys (Functional Ecology and Ecotoxicology of Agroecosystems) joint research unit that studies agroecosystem functioning taking into account the biogeochemical processes, material and energy flows, and the functions of organisms interacting with their environment. You will draw on the skills within the unit to work on both abiotic and biotic processes. Your work will build on the research conducted on the fate of contaminants in the environment, organism exposure, and biological responses, and you will be able to draw on the various analytical platforms of EcoSys. You could also make use of the Ecosys experience on some specific soil biological species to set up experiments, as well as the modelling expertise of Ecosys and collaborators (INERIS, Paris-Saclay University, INRAE) to conceptualise the food webs studied experimentally.You will aim to develop an integrative approach to terrestrial ecotoxicology by working at the interface between the structuring of agricultural and peri-urban soil food webs, the propagation of direct and indirect effects linked to diffuse contamination of anthropogenic origin, and the ecosystem functions and services provided by the soils. You will aim to (1) understand how the contaminants spread within food webs, (2) characterise the propagation of the effects of contaminants within these webs via direct and indirect interactions between the different links in the webs, and (3) quantify the consequences of the structural changes of food webs on certain key functions provided by soil organisms (decomposition and recycling of organic matter, aggregation and porosity dynamics, circulation of water and air). You will thus be required to work on themes relating to the relationships between bioavailability of contaminants and their effects on the structuring of food webs, to conduct experiments on links between biodiversity and soil functioning, or even to identify tools to promote soil compartment resilience against chemical contamination. Your work will highlight tipping points beyond which soil functions can no longer be ensured optimally in the presence of diffuse contamination.You will join the Sol&Tox team within EcoSys, located on the Agro Paris Saclay Campus. The Sol&Tox team studies (i) the links between the fate of soil contaminants and their effects on soil organisms, and (ii) the effect of developments, changes in land use, product recycling, and practices on soil organisms and their function. You will complement the approaches on simplified food webs conducted in the laboratory using experimental approaches in semi-natural conditions from mesocosm to plot level. Your work on the understanding of mechanisms responsible for direct or indirect effects on food webs will complement the modelling work being developed within Ecosys to predict the impact of diffuse contamination of agroecosystems on different biological scales (individuals, populations, communities). You will draw on existing skills in laboratory experimentation within the joint research unit on some specific soil species (worms, springtails, enchytraeidae, ground beetles), as well as in modelling the fate of ecotoxicological effects of organic contaminants. You will complement this expertise through experiments and observations in the field to compare the organisation of complex food webs along anthropisation gradients, drawing more particularly on knowledge relating to soil food webs. You will benefit from the support of the isotope and analytical chemistry platforms to measure the transfers and bioaccumulation of pesticide compounds within food webs. Lastly, you will work with experts in soil science and function to measure the impact of structural variations of food webs on ecological soil functions and services.