INTERACTIVE TOXIC EFFECT AND DISTRIBUTION OF HEAVY-METALS IN PHYTOPLANKTON

Assessing the interactive toxic effect of chemicals in the environment is becoming a matter of increasing public focus on and concern with e cotoxicological aspects. The purpose of this study is to find the rela tionship between an interactive toxic effect and distribution of heavy metals in algal cells. The green alga Chlorella ellipsoidea Gernec(IA MC-27) was cultured for 6 days in the presence of cadmium and/or chrom ium. Algal cells were divided into 4 fractions by centrifugation after the cells were disrupted using a French press. The amounts of the met als in each fraction were determined. The interaction effect between t he two metals on algal growth was investigated. The amount of one meta l taken up in the cells and the growth inhibition rate increased with the concentration of metals in the medium. The amount of one metal in the cells was increased due to the presence of the other metal. Accord ingly, the growth inhibition rate also increased. The amounts of Cd ac cumulated in the soluble fraction and in the membrane fraction of alga l cells were 50 and 20%, respectively, of the total amount in the cell s. The presence of Cr changed the Cd concentration in both fractions t o 40%. The amount of Cr accumulated in each fraction was almost the sa me in the absence of Cd. The amount of Cr accumulated in the cell wall fraction rose to 90% after 3 days of exposure and it stayed as high a s 50% even at the end of the six-day study period in the presence of C d. It was assumed that the presence of one metal influenced the distri bution of the other metal in the cells, which resulted in the synergis tic toxic effect. (C), 1994 by John Wiley & Sons, Inc.