PARENT SESSION

3D - Exposure and effects of environmental contaminants in marine organisms
Hall 7
8:30 AM - 12:30 PM, Tuesday, 29 April 2003
Chair: Scholz, N.¹, ¹
Co-chair: Karbe, L.², ²

(TU7/2) Screening Ecological Risk Assessment for the Venice lagoon aquatic food web: application of bioaccumulation model and Tissue Screening Concentrations for organochlorine compounds.

Micheletti, Christian¹, Critto, Andrea ¹, Semenzin, Elena¹, Ghetti, Pier Francesco¹, Marcomini, Antonio¹, ¹ University Ca' Foscari of Venice, Venice, Italy

ABSTRACT- The highly toxic organic micropollutants stored in the lagoon sediments tend to bioconcentrate and biomagnificate through the food web to reach high concentrations at the top level of the food web, which results in potential risk for the aquatic communities. Risk was estimated by applying the ecological risk assessment procedure developed by US-EPA (1998). The first step was the selection of the preliminary food web model for the Venice lagoon, composed by 14 elements, representing single species or trophic groups: phytoplankton, zooplankton, 3 elements for benthic organisms and 9 for fishes. Risk was estimated for selected PCBs (PCB 126, 81, 126, 118+123) and PCDD/Fs (2,3,7,8 tetra, penta, hexa and epta, CDD/F) congeners. To characterize organism exposure, the Food Chain bioaccumulation model (Gobas, 1994) was adapted to the selected food-web model, and applied for 6 homogeneous geographic areas of the lagoon. Bioaccumulation was estimated in each area by mean and UCL 95% values of micropollutant concentrations in sediment, as well as by the concentrations in water estimated by the fugacity MacKay model. The resulting bioaccumulation shows that congeners with higher log Kow (7.5 - 7.9) concentrated less in fish tissues than congeners with lower log Kow (< 6.5). The ecological effects were characterized by the Tissue Screening Concentrations (Shephard, 1998), obtained multiplying the literature ambient quality criteria by the bioconcentration factor (BCF). Finally, the risk was estimated by rationing the pollutant congeners concentrations in organism tissues (reported as total TEQ), and the Tissue Screening Concentration for the 2,3,7,8 TCDD. The lagoons areas with higher risk resulted affected by industrial and urban discharges, and the trophic groups of concern were benthic filter feeders and omnivorous predators. Within fish community, the highest risk was obtained for juveniles and for species at the top levels of the food web.

Key words: food web, ecological risk assessment, bioaccumulation model, tissue screening concentrations