ABSTRACT
To evaluate the ecotoxic potential of industrial effluent, whole effluent toxicity (WET) testing has been successfully introduced in several countries. This method can potentially be used as an effective monitoring measure for ambient water, such as river water. This chapter provides a case study where the WET tests were applied to river water monitoring. The river water quality of nine rivers was evaluated using short-term chronic toxicity tests, using three kinds of freshwater species. Two types of river water were found to have an adverse effect on daphnia reproduction. In case of one of the samples, the cause was salinity. To investigate the toxicity factors in the other two samples collected from the same river, samples were collected along the river, and a simplified WET test with daphnia and a chemical analysis were conducted. Subsequently, the causative substances and a point source were estimated. Following this, the sample from the suspicious point of discharge (i.e., industrial effluent) was collected and analyzed. High concentrations of V and Ni derived from petroleum coke were detected, suggesting that these were the main causes of toxicity of the industrial effluent as well as of river water samples. From the above results, it was shown that the WET test is effective not only for the evaluation of industrial effluent, but also for monitoring the ambient water.
