INTERACTIONS BETWEEN EUTROPHICATION AND CONTAMINANTS .3. MOBILIZATIONAND BIOACCUMULATION OF BENZO(A)PYRENE FROM MARINE-SEDIMENTS

A major environmental issue is to understand how eutrophication proces ses, such as organic enrichment and hypoxia may act on the distributio n patterns and bioavailability of contaminants to benthic organisms. A n experiment with sediment organic C content (control vs enriched with concentrated phytoplankton) and oxygen level (normoxia vs 2-3 mg O-2 l(-1)) as fixed factors, and C-14-B(a)P in benthic organisms and sedim ent as dependent variable, was conducted for 93 days. Three species of sediment-dwelling organisms with different feeding strategies (Amphiu ra filformis, Nereis diversicolor and Abra alba) were chosen. Blue mus sels (Mytilus edulis), kept in separate aquaria, were exposed to the o utflowing water of the microcosms. Concentration of C-14-B(a)P in the sediment surface at the end of the experiment was significantly higher in the organically enriched sediments than in the control sediments. Accumulation of C-14-B(a)P in A. filformis and N. diversicolor was als o higher in the presence of organic enrichment. Concentrations of C-14 -B(a)P in M. edulis placed downstream of aquaria treated with organic matter were also higher, indicating a higher leaching of bioavailable C-14-B(a)P from the enriched sediments. Hypoxia had no significant eff ect on the sediment distribution and bioaccumulation of C-14-B(a)P, an d there was no significant interaction between hypoxia and organic enr ichment. Our results support the concept of selective feeding on labil e organic matter as a major exposure route of organic contaminants in benthic organisms. (C) 1997 Elsevier Science Ltd.