Résumé
Diffuse pollution due to the application of pesticides is often blamed for groundwater and surface water pollution. In vine growing, copper is still largely used as a fungicide, associated with organic pesticides. The Mediterranean climate leads to runoff and erosion of agricultural fields, favourising the transfer of the pollutants towards surface water. Runoff waters of<br />vineyards were taken and analysed for the study of speciation, bioavailability and toxicity of copper. The purpose of the methodology was to characterise the exposure to copper compared to the other pesticides used in vines treatment. Toxic effects of copper under controlled conditions and in the samples was evaluated on aquatic organisms (bacteria Vibrio fischeri, algae Pseudokirchneriella subcapitata) and allowed us to validate the observed effect with free-ion concentrations. The primary producers being a privileged target within the framework of the contamination by copper, effects on Pseudokirchneriella subcapitata were evaluated at various levels (growth, membrane integrity, photosynthetic activity, esterasic<br />activity) in order to improve the comprehension of the toxicity mechanisms. Test results indicate that growth inhibition is the most sensitive endpoint. The observed effects are interpreted according to the chemical speciation of copper in water : physicochemical<br />characterisation and size fractionation (suspended matter, colloids), modelling of chemical speciation (MINEQL+), evaluation of the potential of mobilisation of the copper from particles. The toxic effect of lipophilic metal complexes, which constitutes an exception to the<br />free ion activity model for bioavailability, was also studied under in vitro conditions. This combined approach (physicochemical characterisation and influence of the speciation of the pollutants on in vitro toxicity) allowed us to identify the parameters that determine transport and toxicity of copper in runoff waters : soil type, rain characteristics and the pesticide<br />application (copper, arsenic, Diuron).