Abstract
Examinations were made on biota and water quality in the rivers of Kyoto city and on a correlation between the ranks of saprobity by biota and values obtained by chemical analysis. For biological evaluation, in every point, colonies of chlorophyta and bacteria on the stones in the bottom of the river, which a man could see with his naked eyes were collected. After they were observed under a microscope, name of biota was identified and then relative frequency of occurrence of various aquatic biota was represented in five ranks of saprobity. From these results, a map of water pollution was drawn. At the same time, electric conductance, pH, transparency, volume of water (ton/sec), disolved oxygen (DO) and biochemical oxygen demand (BOD) were measured. Concerning the relation between BOD and the rank of saprobity, if the rank of saprobity is polysaprobity, BOD value was nearly 10 ppm or over. In the relation of DO to the rank of saprobity, if the rank of saprobity is below β-mesosaprobity, DO value will be more than 5 ppm and, if the rank of saprobity became worse to α-polysaprobity, DO value was below 2 ppm.
