TOXICITY AND MUTAGENICITY OF WASTE-WATERS FROM BAIKALSK PULP AND PAPER-MILL - EVALUATION OF POLLUTANT CONTAMINATION IN LAKE-BAIKAL

Lake Baikal has no agricultural and only little municipal pollution. I nstead a potential source of pollution is the Baikalsk Pulp and paper Mill (BPPM). All waste waters of the mill are mechanically,, biologica lly and chemically, purified and there are sedimentation and aeration ponds at the final stage. In this study the efficient of the waste wat er purification was detected by testing toxicity and mutagenicity, Wat ers and sediments were collected along the cellulose bleaching process and waste water treatment. Free and bound polychlorinated phenols, gu aiacols, catechols, anisoles and veratroles were analysed. Cytotoxicit y of diethylether-extracted waste waters was screened by measuring tot al protein content in a fish hepatoma cell line (PLHC-1). The mutageni city of the water, sediment and tissue extracts of selected aquatic sp ecies was determined by a modified Ames test. Diethylether fractions o f the events from BPPM were cytotoxic for the PLHC-1 cells when concen trated. Biological purification of the waste waters did not effect the cytotoxicity (ED50 similar to 2.2 and similar to 2.0 mu lml(-1) befor e and after). The cytotoxicity, was decreased after chemical purificat ion (ED50 similar to 3.7 mu lml(-1)) and even more after the aeration pond (ED50 similar to 4.2 mu lml(-1)). Mutagens were found in nearly a ll water samples released after the pulp chlorination. However, the mu tagenic activity, was effectively decreased during both biological and chemical treatment of waste waters. Only, the tissue ex-tracts of sea ls and a few roach possessed mutagenic activity. In conclusion, even t he modern waste water purification systems do not totally abolish pote ntial toxicity and/or mutagenicity of the effluents. (C) 1998 Elsevier Science Ltd All rights reserved.