ENVIRONMENTAL-FACTORS AFFECTING THE ACCUMULATION OF SEDIMENT-SORBED HEXACHLOROBIPHENYLS BY CHANNEL CATFISH

Channel catfish (Ictalurus punctatus) fingerlings were used to determine kinetically the accumulation of two symmetrical hexachlorobiphenyl (HCBP) isomers as a function of environmental temperature and sediment organic carbon (OC) content (0.9% and 3.1%). Groups of fish were exposed to each contaminated sediment, spiked with C-14 radiolabelled (2,4,5)2 or (2,3,5)2 HCBP (IUPAC No. 153 and 133) for up to 10 days at 13-degrees-C or 20-degrees-C. The uptake clearance rates (k1) and elimination rate constants (k2) were estimated using first-order uptake and elimination models. Temperature was the more influential parameter tested. Both uptake clearance rates and bioaccumulation factors were affected by changing temperature. Increasing temperature from 13-degrees-C to 20-degrees-C resulted in a 2-4-fold increase of the k1, for both isomers. Sediment OC content also affected the k1, although to a lesser extent than temperature and not in a consistent way. Bioaccumulation factors estimated for the (2,4,5)2 isomer of HCBP were generally lower than those for the (2,3,5)2 HCBP isomer. Increasing temperature and/or sediment OC content resulted in a decrease of the BCFs for (2,3,5)2 isomer but not for (2,4,5)2. These results indicate that environmental hazard may be difficult to predict even when chemicals with similar K(ow) values are considered.