着生微生物のはく離による河川水質への影響

Abstract

The influence of exfoliated periphyton on the pollution in the Kannogawa River flowing into the Lake Inbanuma was investigated by the use of artificial substrata. The dominant species of microorganisms in a periphton community grown up on the artificial substrata changed seasonally, i.e., the sessile algae in summer and sphaerotilus colonies, which forms slime infestation (so-called “Mizuwata”in Japanese), in winter. The growth rate in the early growth stage of periphyton community was higher in summer than winter, but in the middle growth stage it was rather high in winter. The maximum standing crop of periphyton community was appeared in winter. The proportion of carbon and nitrogen to the attached organic matter expressed in I.L. was constant in the every growth stage, but the proportion of phosphorus was high in. the early stage. The water quality in the Kannogawa River became worst in winter. In this season about 47 percent of the total SS load was estimated to be derived from the exfoliation of “Mizuwata”. It was also estimated that annual SS load resulted from exfoliated periphyton in the mouth of the Kannogawa River was approximately 240 ton.