BIOMONITORING AQUATIC POLLUTION WITH FERAL EEL (ANGUILLA-ANGUILLA) .1. BIOACCUMULATION - BIOTA-SEDIMENT RATIOS OF PCBS, OCPS, PCDDS AND PCDFS

Samples of sediments and eel taken from six Amsterdam freshwater sites were analyzed for polychlorinated biphenyls (PCBs), organochlorine pe sticides (OCPs), polychlorinated dibenzofurans (PCDFs) and polychlorin ated dibenzo-p-dioxins (PCDDs). Biota-sediment accumulation factors (B SAFs) were determined from levels in sediments [ng/g organic matter (O M)] and eel muscle tissues [ng/g lipid weight (LW)]. Bioaccumulation p atterns were both site- and analyte-specific. Bioaccumulation of these persistent organic trace pollutants in eel is discussed, considering partitioning, uptake from contaminated water (bioconcentration) and fo od (biomagnification), clearance, and bioavailability. Trends in bioac cumulation profiles indicated the following. Levels of PCBs, DDTs, HCB , PCDFs and PCDDs in eel tissues appeared to be exposure related since they increased with increasing levels of pollution in sediments. High BSAF values indicated that biomagnification contributed significantly to the total bioaccumulation process for PCBs, DDTs and HCB. Higher B SAF values for the higher chlorinated PCBs might be due to a more effi cient biomagnification of these congeners and to a selective metabolis m of the lower chlorinated congeners. Bioaccumulation of HCHs, drins a nd heptachlor compounds; was low in eel. Bioaccumulation of PCDF and P CDD congeners was extremely low in eel. BSAF values of these congeners decreased with increasing chlorine substitution. A large variation in BSAF values for most of the hydrophobic chemicals was observed betwee n different sites. This suggests that bioaccumulation not only depends upon type of organism and analyte, but that site-specific factors sho uld also be taken into account. This might be due to differences in bi oavailability (including desorption kinetics) of the compounds or to d ifferences in the diet of the fish when biomagnification is involved. Estimated PCB toxic equivalent values (TEQs) were higher than calculat ed PCDF/D TEQs at the reference site. The opposite was found at the mo st polluted site.