Spatial and temporal trends in PCBs in sediment along the lower Rhône River, France

Marc Desmet (1) , Brice Mourier (2) , Barbara J. Mahler (3) , P.C. van Metre (3) , Gwenaëlle Roux (4) , Henri Persat (5) , Irène Lefèvre (6, 7) , Annie Peretti (8) , Emmanuel Chapron (9) , Anaëlle Simonneau (9) , Cecile Miege (10) , Marc Babut (10)

1 GéHCO EA6293 - GéoHydrosystèmes COntinentaux
2 Équipe 5 - Impacts des Polluants sur les Écosystèmes
3 US Geological Survey [Austin]
4 LEHNA - Laboratoire d'Ecologie des Hydrosystèmes Naturels et Anthropisés
5 BEL - Équipe 1 - Biodiversité des Écosystèmes Lotiques
6 LSCE - Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette]
7 GEDI - Géochimie Des Impacts
8 IRSTEA - Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture
9 ISTO - Institut des Sciences de la Terre d'Orléans - UMR7327
10 UR MALY - Milieux aquatiques, écologie et pollutions

Despite increasingly strict control of polychlorinated biphenyl (PCB) releases in France since the mid-1970s, PCB contamination of fish recently has emerged as a major concern in the lower Rhône River basin. We measured PCB concentrations in Rhône sediment to evaluate the effects of PCB releases from major urban and industrial areas, sediment redistribution by large floods, and regulatory controls on PCB trends from 1970 to present. Profiles of PCBs (the sum of seven indicator PCB congeners) were reconstructed from sediment cores collected from an off-river rural reference site and from three depositional areas along the Rhône upstream and downstream from the city of Lyon, France. Core chronology was determined from radionuclide profiles and flood deposits. PCB concentrations increased progressively in the downstream direction, and reached a maximum concentration in 1991 of 281 μg/kg at the most downstream site. At the rural reference site and at the upstream Rhône site, PCB concentrations peaked in the 1970s (maximum concentration of 13 and 78 μg/kg, respectively) and have decreased exponentially since then. PCB concentrations in the middle and downstream cores were elevated into the early 1990s, decreased very rapidly until 2000, and since then have remained relatively stable. Congener profiles for three time windows (1965-80, 1986-93, and 2000-08) were similar in the three sediment cores from the Rhône and different from those at the rural reference site. The results indicate that permitted discharges from a hazardous-waste treatment facility upstream from Lyon might have contributed to high concentrations into the 1980-90s, but that industrial discharges from the greater Lyon area and tributaries to the Rhône near Lyon have had a greater contribution since the 1990s. There is little indication that PCB concentration in sediments downstream from Lyon will decrease over at least the short term.

Mots clés: Polychlorinated biphenyl (PCB); Rhône River; Sediment core; Spatial and temporal trends

Domaines: Interfaces continentales, environnement; Milieux et Changements globaux; Géomorphologie

Marc Desmet, Brice Mourier, Barbara J. Mahler, P.C. van Metre, Gwenaëlle Roux, et al.. Spatial and temporal trends in PCBs in sediment along the lower Rhône River, France. Science of the Total Environment, 2012, 433, pp.189-197. ⟨10.1016/j.scitotenv.2012.06.044⟩. ⟨insu-00724511⟩