Abstract
Sediments contaminated with nutrients, metals, metalloids, organics, and oxygen-consuming substances etc. can be found in freshwater, estuarine, and marine system throughout the world. Concentrations have been used historically and are still being used to assess sediment quality as an index of chemical contaminants, but such chemical criteria do not always show the toxicity strengh of sediments. The purpose of this study is to evaluate sediments toxicity sampled from Kojima Lake basin using the yeast Saccharomyces cerevisiae. The lag-time at the yeast growth phase was found to be the most sensitive toxicity index among the growth characteristics. The mode of dose-effect curve of environmental samples was different from that of chemicals such as heavy metals when they were administered alone. The toxicity of sediment sampled in spring is higher than in the other three seasons. The toxicity of Kojima Lake samples is higher than those of the two rivers in the same basin. Toxicity of acetone extracts is higher than that of n-hexane extracts from sediments. The yeast S. cerevisiae can be a good biological species to assess sediment toxicity.
