A method for calculating effects, on aquatic organisms, of time varying concentrations

A method is presented for calculation of the effects, on aquatic organisms, of exposure to time variable concentrations of toxicants. The technique employs data from classical bioassay tests obtained using constant toxicant concentrations. Calculations of organism mortality as a result of exposure to time varying concentrations are compared to observed data providing a test of the proposed method. The calculation procedure employs available data to assess the duration and extent of carry over effects from individual exposures. Applications and limitations of the proposed method conclude the discussion.