Quantification and characterization of chronic inputs of trace metals and organic carbon in a coastal Med-iterranean area (the city of Marseille) during the dry season was carried out. The 625 km 2 watershed includes two small coastal rivers whose waters are mixed with treated wastewater (TWW) just before their outlet into the sea. Dissolved and particulate Cu, Pb, Cd, Zn, Co, Ni and organic carbon concentra-tions in the rivers were comparable to those in other Mediterranean coastal areas, whereas at the outlet, 2-to 18-fold higher concentrations reflected the impact of the TWW. A non-conservative behavior observed for most of the studied metals in the mixing zone was validated by a remobilization experiment performed in the laboratory. The results showed that sorption/desorption processes could occur with slow kinetics with respect to the mixing time in the plume, indicating non-equilibrium in the dis-solved/particulate metal distribution. Thus, a sample filtration immediately after sampling is strictly required.