EXPERIMENTAL FIELD EXPOSURE OF BROWN TROUT TO RIVER WATER RECEIVING EFFLUENT FROM AN INTEGRATED NEWSPRINT MILL

Effects of effluents from mechanical pulp production on brown trout we re studied for 8 weeks at environmentally relevant concentrations. The exposure took place in laboratory-based pools upstream and downstream of the effluent discharge point of an integrated newsprint mill using ground woodi thermomechanical pulp. The mill had no secondary treatme nt of the wastewater. The pools were supplied with water pumped direct ly from the river. To determine the relevance of this approach, wild f ish were also caught at the respective sites upstream and downstream f rom the mill, Sublethal effects were assessed using physiological and biochemical parameters including liver histology, hematology, serum bi ochemistry, and hepatic enzyme assays. Exposure was verified by analyz ing water samples, fish bile, and tissues for resin acid concentration s. The downstream experimental fish and captured feral fish displayed responses and changes in physiological parameters similar to those pre viously observed in laboratory experiments with untreated effluents, T he most obvious effects were liver damage and growth inhibition. (C) 1 998 Academic Press.