The overall focus of my research concerns the study of interactions between major and trace elements and major constituents of water and soil in biogeochemical cycles. Continental surfaces are the locus of significant transfers and exchanges of materials. At the watershed scale, these transfers are made in a large geochemical cycles: weathering of rocks - transport by rivers - sedimentation - diagenesis. To understand these transfers and the environmental role of organic matter, it is necessary to determine the speciation of chemical elements in the environment: dissolved, colloidal, and / or solid. The adsorption and complexation of major and trace elements by finely divided materials (ie colloidal minerals, organo-inorganic and organic) influence transfer processes in rivers and soils.