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(70-36) Copper speciation, bioavailability and toxicity in runoff waters from contrasted fields and receiving aquatic ecosystems in a multipollution context. Devez, Aurélie*,1, Gilbin, Rodolphe1, Gomez, Elena1, Persin, Françoise2, Andrieux, Patrick3, Casellas, Claude1, 1 DSESP, University of Montpellier, Montpellier, France2 IEM-LMPM, CNRS, Montpellier, France3 Soil Science Unit, INRA, Montpellier, France ABSTRACT- Vineyard protection is correlated with the use of copper and arsenic as fungicides, alone or in combination with organic molecules. To assess the effects of metal contaminants in aquatic systems, information on both speciation and bioavailability is needed. The purpose of this study was to determine relationships between speciation of copper and toxicity results in environmental samples. In the studied Mediterranean vineyard catchment, transport of metals from soils to river depend on soil characteristic and occurrence of heavy storm flow period. Samples were taken from surface runoffs on two experimental fields which differ from soil type (calcareous and acidic) and from the receiving aquatic ecosystem, the Peyne river. Physical-chemical characteristics were measured and total concentration of Cu, Zn and As were quantified in the dissolved phase by ICP-MS. A voltammetric method -Differential Pulse Anodic Stripping Voltammetry with a hanging mercury drop electrode- was used to measure the labile species of copper (free metal ion and labile metal complex) which correspond to form currently thought to be responsible for most of the toxicity in aquatic system. Ecotoxicological testings were conducted, in parallel, with green algae Pseudokirchneriella subcapitata. Different endpoints -absorbance, chlorophyll fluorescence, esterase activity and membrane integrity- would be compared. No toxicity was observed on the acidic runoff waters, on the contrary toxicity on the calcareous samples seems to be partially linked to copper speciation. In multipollution complex, we don't neglect the other contaminants (arsenic and organic pesticides) and the interactions metal-ligands in the final interpretation. Key words: copper speciation, bioavailability, toxicity, DPASV |
