J. Phys. IV France 107 (2003) 135
DOI: 10.1051/jp4:20030261

Cadmium contamination of three bivalve species (oysters, cockles and clams) in Nord Médoc salt marshes (Gironde estuary, France): Geochemical survey and metal bioaccumulation kinetics

M. Baudrimont¹, J. Schäfer², V. Marie¹, R. Maury-Brachet¹, C. Bossy², G. Durrieu¹, A. Palvadeau¹, E. Maneux², A. Boudou¹ and G. Blanc<sup>2

1</sup>  Laboratoire d'Écophysiologie et Écotoxicologie des Systèmes Aquatiques, LEESA, Université de Bordeaux I, UMR 5805 du CNRS, EPOC, place du Dr. Peyneau, 33120 Arcachon, France
²  Department of Geology and Oceanography, DGO, Université de Bordeaux I, UMR 5805 du CNRS, EPOC, avenue des Facultés, 33405 Talence cedex, France

Abstract
A historical Cd pollution of the Lot-Garonne River system (France) bas led to the contamination of sediment and water of the Gironde Estuary. In spite of the decrease of fluvial Cd inputs since the early 90ies, Cd concentrations in the Gironde oysters remain higher than European norms (5 g.g ^-1 dry mass) and the "zone D" classification of the estuary prohibits bivalve production and harvesting for human consumption. A geochemical survey in salt marshes used for aquaculture (crustaceans) has been conducted in order to assess the heavy métal contamination level in these systems periodically alimented by the Gironde water, accompanied by caging experiments on three bivalve species of economical interest: oysters (Crassostrea gigas), cockles (Cerastoderma edule ) and clams (Ruditapes philippinarum) to study heavy metal accumulation in these organisms. Distribution of heavy metals in this system is controlled by biogeochemical processes and is independent of routine water management. Contamination levels in the studied species indicate the high accumulation of Cd by oysters. On the other hand, Cd concentrations in benthic species, such as cockles and clams, are clearly lower than European safety limits for human consumption.

© EDP Sciences 2003