MONITORING TOXICITY IN 4 WASTEWATERS IN THE BAY-OF-QUINTE, LAKE-ONTARIO

In 1993, as part of the Bay of Quinte Remedial Action plan program, the toxicity of four wastewater discharges (two from municipal STPs, one from a chemical company, and one from a pulp and paper company) was monitored in the Bay of Quinte, Lake Ontario. Sequential dilutions of the best effluents were utilized in algal assays to estimate effluent toxicity at 100% effluent concentration. The toxicity estimated was expressed as mu M/L Cu equivalents. Among the four discharges tested the paper processing effluent was the most toxic at about 100 times the sensitive level (the concentration above which delicate algal and invertebrate species would not survive). STP-I wastewater was not toxic. The toxicity of both the chemical company and STP-II wastewaters fluctuated in and out of the sensitive zone. Chlorella cells harvested after six days exposure to the industrial wastewaters sustained fine structural damage caused by organic toxicants, while those incubated with municipal STP wastewaters exhibited damage due to metals. in the absence of organic toxicity in STP-II wastewater, a negative correlation between P concentration and metal toxicity was obtained (r(2) = 0.99).