LAUSR

The occurrence of eight pharmaceutical products (PPs) from various therapeutic classes was studied in urban sediments collected upstream a small dam in Orleans, France. Since PPs are globally distributed contaminants since the 1950s, their spatial and historical distribution was documented in order to better understand the impact of recent urban management on the chemical quality of sediments. Concentrations of the PPs mainly ranged between 1 and 10 ng g-1 within the two cores. The chronology of core LOI13-2, based on radionuclide analysis (137 Cs and 210 Pb), enabled the characterization of the changes or shift in PPs over the last 50 years, impacted by the effluent deflections i) of a large wastewater treatment plant in 1989, and ii) of 3 smaller wastewater treatment plants between 2003 and 2009. In most cases the deepest occurrence of each PP in the core matched the market authorization date of different pharmaceuticals, indicating that some PPs can be used as chronomarkers. The study reveals that recent management of effluent discharges within the watershed improved the chemical quality of these sediments. In view of the persistence of PP pollution in trapped sediments, a total stock of 763±565 g for the selected PPs was estimated at the millstream scale. Superficial sediments therefore represent a potential source of downstream pollution in the event of the removal of a small existing dam.