PARENT SESSION
MP8a Site-Specific Ecological Risk Assessment.
3:00 PM to 4:00 PM, Monday, 07 May 2001
Session Chair: Lorraine Maltby
Room 8

(135) Developing site specific Ecological Risk Assessment through estimations of bioaccumulation in an edible organism (Tapes ph.).

Marcomini, Antonio¹, Critto, Andrea¹, Bertazzon, Stefania¹, Carlon, Claudio¹, Micheletti, Christian¹, ¹

ABSTRACT- The Ecological Risk Assessment procedure (ERA) developed by US EPA (EPA/630/R-95/002F) was applied to estimate the risk associated with the clam Tapes philippinarum. This is an edible benthic organism, widespread in the lagoon of Venice, which is cought to an extent of ca. 30.000 ton per year. Tapes ph. is exposed to organic and inorganic micropollutants occurring in the shallow (ca. 1 m) bottom sediment of the lagoon. The ERA procedure allowed to achieve the risk estimation through the comparison of the results obtained from the characterization of exposure and effects, respectively. The exposure was assessed by two approaches, one based on the spatial correlation of experimental whole sediment concentrations (Cressie, 1993), a second one based on the food chain partitioning and bioaccumulation models proposed by Gobas (1994). The former approach allowed to define spatial regression models between the pollutant concentration measured in the clam tissues and other experimental parameters such as lipid content of the organism, pH, TOC, fine fraction and pollutant concentration of the sediment. The spatial analysis, carried out by SpatialStat of S-Plus^© (MathSoft, Inc., 1996), allowed to calculate the spatial autocorrelation and thus to obtain highly space-specific results. The second approach applied the food chain bioaccumulation model (SREM, 1994) developed at the Saimon Fraser University, Canada. The effects were assessed by using two types of ecological benchmarks, one type consisting of toxicological parameters (LC₅₀, NOAEL, etc.) available for Tapes ph. in international data sets, the second type being obtained according to the Shephard's method (1998). The latter allowed to obtain the benchmarks, in terms of tissue concentration limits, from the Ambient Water Quality Criterion (AWQC). The risk was estimated from the direct comparison of calculated bioaccumulation values with the corresponding benchmark values, according to the method of toxic units (Chapman et al., 1997).

Key words: Ecological Risk Assessment, Bioaccumulation, Tapes Philippinarum, Spatial Analysis