Environmental factors affecting the accumulation of sediment-sorbed hexachlorobiphenyls by channel catfish

Abstract

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 14C radiolabelled (2,4,5) 2 or (2,3,5) 2 HCBP (IUPAC No. 153 and 133) for up to 10 days at 13°C or 20°C. The uptake clearance rates ( k 1) and elimination rate constants ( k 2) 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°C to 20°C resulted in a 2–4-fold increase of the k 1, for both isomers. Sediment OC content also affected the k 1, 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.