EFFECT OF SEDIMENT ON THE BIOACCUMULATION OF A COMPLEX MIXTURE OF POLYCHLORINATED DIBENZO-P-DIOXINS (PCDDS) AND POLYCHLORINATED DIBENZOFURANS (PCDFS) BY FISH

Guppies (Poecilia reticulata) were exposed to a complex mixture of pol ychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofura ns (PCDFs) in the presence and absence of sediment for 21 days. Since the guppies were separated from sediment to prevent uptake of sediment into the intestines, uptake was possible only from water. The accumul ation kinetics, bioconcentration factors and biota-sediment accumulati on factors were determined for 13 toxic PCDD and PCDF congeners. PCDDs and PCDFs were bioavailable to fish. In the presence of sediment, how ever, the accumulation was reduced compared to the accumulation in the system without sediment. Bioconcentration factors were reduced betwee n 15% for 2,3,7,8-TCDF and 82% for OCDD by the presence of sediment. R eduction is probably caused by the introduction of organic matter in t he water. Biota-sediment accumulation factors ranged from 0.155 for 2, 3,7,8-TCDD to 0.003 for OCDD. The effects of sediment increased with i ncreasing hydrophobicity of the compounds.