Assessment of the impact of a bleached kraft mill effluent on a south-central USA river

Abstract

We initiated a multifaceted, integrated investigation of the general health of the aquatic environment near a bleached kraft pulp and paper mill. This southcentral U.S. mill discharges about 125,000 cubic meters of treated effluent per day into an adjacent river. The sampling sites for this study were 1.8 km upstream from the mill's discharge, 0.25 km below the mill's outlet, and 5 km downstream from the discharge area. No toxicity was observed using Ceriodaphnia dubia and Pimephales promelas in aqueous phase tests or with Hyalella azteca and Chironomus tentans in sediment phase tests. Field examinations of two small fish species and sediment macroinvertebrate communities from each sampling site revealed no significant adverse effects. Bluegill sunfish (Lepomis macrochirus) were exposed for 35 days to site sediments and were evaluated for ethoxyresorufin O-dethylase (EROD) activity, cytochrome P4501A (CYP1A) content, DNA strand breaks, condition index, organ indices, gross pathology, and immune responses. No significant adverse effects were observed in sediments immediately below the mill's effluent outlet, though detoxification enzyme activity was elevated in liver tissue of bluegill sunfish exposed to site 3 sediment. Embryos of mosquitofish (Gambusia affinis) were evaluated for developmental and reproductive abnormalities following a static laboratory exposure of gravid females to sediments from the three study sites for 56 days. The embryos showed no significant effects on a suite of reproductive parameters among the three sites. We concluded that there was no significant evidence of adverse impacts on the receiving river or its biota attributable to treated bleached kraft mill effluent based on a comprehensive suite of bioindicators of exposure and effects. ©2000 John Wiley & Sons, Inc. Environ Toxicol 15: 28–39, 2000