INTERACTIVE TOXIC EFFECT AND BIOCONCENTRATION BETWEEN CADMIUM AND CHROMIUM USING CONTINUOUS ALGAL CULTURE

Numerous studies have been conducted on the effects of toxic chemicals using algal batch culture. On the other hand, continuous culture rese arch has the advantage of allowing optimal cell growth. Few studies on the interactive toxic effect between chemicals have been carried out either with batch culture or with continuous culture. The purpose of t his study is to find the relationship between interactive toxic effect s and the bioconcentration of heavy metals using continuous algal cult ure. The green alga Chlorella ellipsoidea was used as a test organism. As test substances cadmium and chromium were used. The amount of heav y metals both in algae and in the medium was determined after the cell s had been exposed to heavy metals for 10 days. The amount of Cd taken up in the cells and the growth inhibition rates caused by Cd increase d as the concentration of Cd in the medium became higher. The inhibiti on rates rose drastically but the amount of Cd in the cells remained a t almost the same level even if Cr was added. The bioconcentration fac tors of Cd were ca. 10,000 in all the cases tested, regardless of the presence of Cr. The amount of Cr in the cell exposed to Cr was low, wh ile that amount and the growth inhibition rates for all the concentrat ions tested increased when Cd was added to the medium containing Cr. T he bioconcentration factors of Cr reached 156,000 as the concentration of Cd in the medium increased. It seems that the toxicity of Cr was e nhanced because the presence of Cd in the medium raised the amount of Cr in the cell. (C) 1993 John Wiley & Sons, Inc.