Comparing pharmaceutical and pesticide loads into a small Mediterranean river.

During 2003/2004, water samples were collected upstream and downstream of two wastewater treatment plant (WWTP) outlets in order to determine the contribution of urban centres to concentration of selected pharmaceuticals (antiphlogistics, lipid regulators and carbamazepine) and pesticides into a Mediterranean river basin (Arc river, Aix en Provence, France). Pharmaceutical loads were compared to pesticide ones. They could be nearly regarded as important as pesticide ones at least at one sampling site. The observed pollution patterns differed from pesticides to pharmaceuticals. Pesticide pollution occurred through a high pollution peak in spring while pharmaceuticals were continuously infused into the river via WWTP effluents. Carbamazepine and bezafibrate were detected in almost all samples at concentration levels ranging from ng/L to microg/L. The major pharmaceutical source could be ascribed to WWTP effluents and pharmaceutical concentrations increased during low flow rate conditions (summer), when municipal wastewater effluents accounted for the majority of the river water flow. Treated wastewaters contributed to a lesser extent to pesticide river water pollution. In an urbanized Mediterranean river basin, a deep understanding of water pollution by organic waste contaminants is required in order to set up an efficient programme of pollution reduction measures.