ACCUMULATION OF POLYCHLORINATED ORGANIC CONTAMINANTS FROM SEDIMENT BY 3 BENTHIC MARINE SPECIES

A laboratory experiment was conducted to measure the accumulation of selected polychlorinated compounds by marine benthos exposed to environmentally contaminated sediment. Sandworms (Nereis virens), clams (Macoma nasuta), and grass shrimp (Palaemonetes pugio) were exposed to sediment collected from the Passaic River, New Jersey. All three species accumulated 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3, 7,8-TCDD), 2,3,7,8-tetrachlorodibenzofuran (2,3,7,8-TCDF) and polychlorinated biphenyls (PCBs) from the sediment. In addition, a recently identified sulfur containing analog of tetrachlorinated dibenzofurans, 2,4,6,8-tetrachlorodibenzothiophene (2,4,6,8-TCDT), accumulated in the three species. Accumulation factors (AFs) were calculated (([organism]/lipid)/([sediment]/total organic carbon)) and used to compare results among species and compounds. These comparisons showed that AFs measured for clams reached steady-state levels rapidly (10 days); however, steady-state AFs values were not achieved until 70-120 days in sandworms. Grass shrimp were exposed to test sediments for only 28 days; therefore, steady-state concentrations could not be determined for this species. Although final contaminant concentrations were highest in the sandworms, AFs were generally higher for the clams and shrimp and lower for the sandworms. The AFs for 2,4,6,8-TCDT were significantly higher for shrimp than for sandworms and clams. PCB 153 showed higher AF values than those of the other compounds studied. Clams showed preferential accumulation of lower molecular weight PCB congeners which may be due to the very low lipid content in this species. Sandworms and especially shrimp appeared to metabolize congeners 52, 101, and 151 which all contain vicinal hydrogens in the meta and para regions of the molecule.