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

Channel catfish (Ictalurus punctatus) fingerlings were used to determi ne 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 expo sed 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 elimina tion rate constants (k2) were estimated using first-order uptake and e limination models. Temperature was the more influential parameter test ed. Both uptake clearance rates and bioaccumulation factors were affec ted 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 is omers. Sediment OC content also affected the k1, although to a lesser extent than temperature and not in a consistent way. Bioaccumulation f actors 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 i somer 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.