DEVELOPMENT OF AQUATIC PLANT BIOASSAYS FOR RAPID SCREENING AND INTERPRETIVE RISK ASSESSMENTS OF METAL MINING LIQUID WASTE-WATERS

The use of non-photosynthetic organisms alone to describe environmenta l impact has been recognized by regulatory agencies, industry, and aca demia as being insufficient both in Europe and North America. Lack of adequate testing methods for photosynthetic aquatic organisms is consi dered as a major impediment to the successful regulation and safe use of pesticides and waste water discharges and is of even more concern t o the metal mining industry due to the non-biodegradable nature of its waste streams. This work shows that the chemical effluent limits set in the ''Metal mining liquid effluent regulations and guidelines'' pro vide variable protection of aquatic photosynthetic organisms. Aquatic effects of the more toxic metals (e.g., copper, nickel, and zinc) may occur at levels that are one to two orders of magnitude lower than pre sent limits. To establish adequate protection of receiving water bodie s it may be necessary to establish site-specific criteria taking into consideration toxicity modifying factors of individual sites. Ii the e stablishment of such criteria is determined with a host of ecologicall y relevant organisms, it will be possible to design effective environm ental protection at the least possible cost. Copyright (C) 1996 IAWQ.