Predicting chemical contaminants in freshwater sediments through the use of historical biochemical endpoints in resident fish species.

Previous studies in Bayou Bartholomew, Arkansas, USA, indicated significant relationships between the individual health of fish sampled from 13 sites and specific biochemical responses. Evaluation of several biochemical endpoints in 1994 indicated the bioavailable occurrence of either polychlorinated biphenyl (PCB) congeners or metals. To evaluate this possibility, in December 2000, sediments were collected at four sites on Bayou Bartholomew, where fish, collected in July 1994, had previously demonstrated the highest hepatic cytochrome P4501A (CYP1A) and heme oxygenase (HO) expression. Samples were analyzed for 89 PCB congeners, 18 organochlorine pesticides, and 25 metals. Total PCB concentrations ranged from 6.5 to 704 ng/g dry weight. Although several PCB congeners were observed, 81, 87, 99, 114, and 153 represented up to 33, 22, 29, 92, and 55% of the sum of PCBs from the four sites, respectively. Total organochlorine pesticide concentrations ranged from undetectable to 53.2 ng/g dry weight. Lindane, heptachlor, dachtal, dieldrin, hexachlorobenzene, dichlorodiphenyltrichloroethane (DDT), dichlorodiphenyl ethane (DDE), and dichlorodiphenyl dichloroethane (DDD) isomers were detected in most samples. Detected organophosphate pesticides included malathion, chlorpyrifos, and dimethoate. Both p,p'-DDE and p,p'-DDD were the most predominant of the pesticides measured (0.5-14.1 and 0.7-58.5 ng/g dry wt). All metal concentrations analyzed were below sediment quality guideline values. Metals exceeding national average concentrations were cobalt (2 of 4 [2/4] sites), copper (1/4), molybdenum (4/4), antimony (3/4), selenium (4/4), tin (4/4), and zinc (1/4). These results were consistent with PCBs being causative agents for the biochemical and adverse individual responses observed in fish sampled from this waterway.