水生生物

This study was conducted in order to evaluate the combined action of chemicals on the growth of the green alga, Selenastrum capricornutum and on the glucose consumption of microorganism populations in medium where many chemicals from among the environmental water quality standard items relating to human health in Japan coexist, Tests were conducted under three conditions： (1) medium containing a mixture of the standard levels of 13 chemicals from among the environmental standard items (26 chemicals); (2) medium containing a mixture of the guideline levels of 18 chemicals frbin among the items requiring close monitoring (22 chemicals)； (3) medium containing a mixture of the standard levels plus the guideline levels of a combination of the 31 chemicals from among the environmental standard items and the items requiring close monitoring (environmental water quality standard items), The three kinds of tests and their respective dispersant controls (A), (B) and (C) were the same as regards the concentrations and kinds of dispersants used, The results are summarized as follows, 1) At the end of the growth inhibition tests, the number of cells of the test alga in the above tests (1), (2) and (3) had decreased to 57,9, 63,3 and 56,6%, respectively, in comparison with the findings for each of the dispersant controls, The growth of the test alga was inhibited under each of the three test conditions, 2) At the end of the glucose consumption inhibition tests, the amdunt of glucose consumption of the test microorganisms in the above tests (1), (2) and (3) had decreased to 60,1, 58,9 and 63,7%, respectively, in comparison with the findings for each of the dispersant controls, The amount of glucose consumption of the test microorganisms was inhibited under each of the three test conditions, 3) ln addition, the mutagenicities under each of the three test conditions・and those of each of the dispersant controls were examined by the Ames test using Salmonella Typhimurium TAIOO, However, mutagenicities were not observed either in the presence or the absence of the microsomal preparation (S9mix), Judging from the results described above, it would seem that the current environmental water quality standards present some problems with regard to the protection of living aquatic organisms in public water areas, such as rivers, lakes, and coastal waters where the standard levels and the guideline levels of many of the chemicals from among the environmental water quality standard items coexist.