title: Bioturbation effects on cadmium and zinc transfers from a contaminated sediment and on metal bioavailability to benthic bivalves.
abstract: The two main objectives of this study were to compare cadmium and zinc fluxes from a contaminated sediment to the water column in bioturbated and unbioturbated systems and jointly to analyze accumulation kinetics of these released metals by benthic filter-feeder bivalves. The experimental approach was based on indoor microcosms containing a two-compartment biotope: natural contaminated sediment (45 +/- 5 microg Cd/g, dry wt, and 1,938 +/- 56 microg Zn/g, dry wt) and water column. Four experimental conditions were studied: no organism added to the sediment-water biotope, presence of bivalves Corbicula fluminea, presence of Hexagenia rigida nymphs (bioturbation source), and presence of C. fluminea and H. rigida simultaneously. Results reveal that bioturbation produces a significant metal release into the water column via the resuspended sediment particles. The use of C. fluminea as an indicator of transferred metals in the water column shows that the metal bioavailability is very limited, quantities of cadmium and zinc bioaccumulated in the soft bodies being less than those measured in unbioturbated systems. This experimental study demonstrates that only the dissolved fraction resulting from diffusive metal fluxes across the sediment-water interface is bioavailable for this bivalve species.
authors.affiliation: Unité Mixte de Recherche 5805, Laboratoire d'Ecophysiologie et Ecotoxicologie des Systèmes Aquatiques, Université Bordeaux 1--CNRS, Place du Docteur Peyneau, 33120 Arcachon, France.
authors.forename: Aurélie
authors.initials: A
authors.lastname: Ciutat
authors.forename: Alain
authors.initials: A
authors.lastname: Boudou
mesh_terms: D000818:Animals; D001682:Biological Availability; D002104:Cadmium / Q000032:analysis* / Q000493:pharmacokinetics*; D019015:Geologic Sediments / Q000737:chemistry*; D008974:Mollusca; D014018:Tissue Distribution; D014867:Water / Q000737:chemistry; D014873:Water Pollutants / Q000032:analysis* / Q000493:pharmacokinetics*; D015032:Zinc / Q000032:analysis* / Q000493:pharmacokinetics*
chemical_list: D014873:Water Pollutants; D002104:Cadmium; D014867:Water; D015032:Zinc