Source and identity of compounds in a thermomechanical pulp mill effluent inducing hepatic mixed-function oxygenase activity in fish

The source and identity of two mixed-function oxygenase (MFO)-inducing substances present in the primary-treated effluent of a thermomechanical pulp (TMP) mill producing newsprint was determined. The source was pinpointed by exposing rainbow trout (Oncorhynchus mykiss) to various process effluents sampled throughout the mill. Exposure concentrations were based on the flow of these process streams in relation to the final effluent flow. Contaminated TMP steam condensates were identified as the major process source of MFO-inducing substances. Using conventional extraction and fractionation procedures, an MFO-inducing fraction was isolated. The major gas chromatographic peaks in this fraction were identified by gas chromatography/mass spectrometry as juvabione, dehydrojuvabione, and manool, all naturally occurring extractives in balsam fix (Abies balsamea). These substances were extracted and isolated from balsam fir and TMP condensates. Trout exposed to juvabione and dehydrojuvabione responded by exhibiting significant hepatic MFO inductions. No MFO induction was observed for manool. Secondary treatment in an activated sludge system effectively eliminated the MFO-inducing potential of the combined mill effluent consistent with a corresponding 90% reduction of both juvabione and dehydrojuvabione