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 thermomechani cal 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 concentration s were based on the flow of these process streams in relation to the f inal effluent flow. Contaminated TMP steam condensates were identified as the major process source of MFO-inducing substances. Using convent ional extraction and fractionation procedures, an MFO-inducing fractio n was isolated. The major gas chromatographic peaks in this fraction w ere identified by gas chromatography/mass spectrometry as juvabione, d ehydrojuvabione, and manool, all naturally occurring extractives in ba lsam fix (Abies balsamea). These substances were extracted and isolate d from balsam fir and TMP condensates. Trout exposed to juvabione and dehydrojuvabione responded by exhibiting significant hepatic MFO induc tions. No MFO induction was observed for manool. Secondary treatment i n an activated sludge system effectively eliminated the MFO-inducing p otential of the combined mill effluent consistent with a corresponding 90% reduction of both juvabione and dehydrojuvabione.