Historical trends of PCBs, PAHs, PBDEs and alkylphénols in dated sediments from flood plains of the Seine River (France)

The Seine River basin (79,000 km2, 20 millions inhabitants) is considered as representative of river basins exposed to the impacts of intense human activity due to the combination of strong human pressures with very limited dilution via the Seine River (mean flow : 290m3/s in Paris). To obtain a chronological overview of the POP-contamination of the basin a sediment-core from flood-plains downstream Paris was collected and analysed. Hence, a 100-cm vertical core was taken close to Bouafles, 100 km downstream Paris (draining about 96 % of the basin) and then divided into 50 2-cm samples. The core was dated by gamma spectrometry of radionuclides 210Pb, 137Cs and 241Am. Then four groups of organic contaminants were analyzed: polychlorinated biphenyls (PCBs), polycyclic aromatic compounds (PAHs), polybromodiphenyl ethers (PBDEs) and alkylphenols (APs). The objectives of this work were i) to determine the concentration and the historical contamination for each family and congener and ii) to compare these historical profiles to the production and consumption patterns. Results show a very high contamination caused mainly by the industrial and urban activity of Paris region. Moreover the temporal profiles clearly underlined strong behaviour differences between pollutants over the period considered (1940-2004). For example, PAHs and PCBs concentrations respectively peaked at the end of the 1950s and in the 1960s and then sharply declined. On the contrary PBDEs peaked around 1990. Globally, the historical profiles fit with the production and consumption patterns for most contaminants. To better understand the time profiles, the next step will more precisely examine their evolution in relation to the evolution of the Seine basin and especially of the Paris region, regarding its urbanization and/or industrialisation