Bioaccumulation of pulp mill effluent-related compounds in aquatic animals

Abstract

The effect of low and high molecular weight fractions of a bleached kraft pulp mill effluent on the bioaccumulation of 2,3,7,8-tetrachlorodibenzo- p-dioxin (TCDD) was determined in laboratory experiments using radiolabeled compound. The bioaccumulation of extractable organic halogen compounds (EOX) was studied both in the laboratory and in the recipient of a pulp mill using mussel ( Anodonta anatina L.) and fish (almo salar L.) as the test organisms. The bioaccumulation of TCDD decreased considerably in the presence of high molecular weight chlorolignin (> 10000). Decreased bioavailability is probably due to binding of TCDD to the macromolecules. Static experiments indicated no significant bioaccumulation of low and high molecular weight chloroorganics (EOX) in mussel or fish. However, the experiments with a flow-through setup showed marked bioaccumulation of low molecular weight chlorocompounds in mussels. The concentration of EOX in the fat of mussels exposed for 7 days to low molecular weight (< 1000) effluent fraction was approximately the same as that of mussels exposed for 5 months in the lake recipient of a pulp mill. Most of the bioaccumulated EOX was excreted during a 5-day depuration period. The results show that EOX determination may be used to assess bioaccumulation of pulp mill effluent-related chlorinated compounds in aquatic animals, although the analysis of low molecular weight compounds such as chlorophenols is probably a more sensitive method. EOX analysis is much easier and quicker to perform.