THEORETICAL EVALUATION OF THE INHIBITORY EFFECTS OF MERCURY ON ALGAL GROWTH AT VARIOUS ORTHOPHOSPHATE LEVELS

Mercury toxicity on Selenastrum capricornutum was examined by a chemostat culture system. Phosphorus concentration within the system was controlled by means of maintaining different dilution rates of the chemostat. The study shows that EC(50) is consistently correlated with the phosphorus concentration. The sample correlation coefficient (r) between EC(50) and PO4-P concentration is found to be 0.87, which suggests that EC(50) is likely to be influenced by the phosphorus concentration. This phenomenon can be explained by a theory which describes the correlation between the tolerance and the activation level. The study indicates that nutrient conditions constitute an important factor in algal toxicity tests.