Change in Fish Toxicity of LAS during biodegradion

Abstract

In case of evaluating possible effects on fish of lower levels of anionic surfactants present in the natural aquatic environment, the authors thought that it was necessary to examine the effect of LAS on Japanese killifish, Oryzias latipes, in a dynamic system taking account of molecular change caused by biodegradation. Considering the decrease in surfactant molecules and the changes in the distribution of the homologues and isomers of LAS (linear alkylbenzene sulfonate), the influence of LAS in the course of biodegradation on the mortality and hatchability of Japanese killifish was determined using a continuous flow river model. And the results was compared with the case of intact LAS in a static bioassay system. It was shown that biodegraded LAS was less toxic for every stage of killifish in the river model than was intact LAS in the static bioassay. The longer alkyl chain homogues and external phenyl isomers, although more toxic for fish, were more rapidly biodegraded. To evaluate the effects of easily biodegradable chemicals such as LAS present in the natural aquatic environment on aquatic organisms, the use of river models appears to be a promising new technique for the study of various environmental factors, e.g., biodegradation. © 1977, The Japanese Society of Fisheries Science. All rights reserved.