Water Quality Chart of the River Yamato-gawa

Using Diatom Assemblage Index to Organic Water Pollution ( DAIpo ) Based on Attached Diatom Assemblage on River Bed.

Abstract

The diatom communities in the River Yamato-gawa, a most polluted diver in Japan, were surveyed in October 1985. In these communities, we can find Navicula minima, Navicula mutica, Nitzschia palea, Nitzschia amphibia or Nitzschia frustulum var. perpusilla ( the former three are Saprophilous taxa and the latter two are Eurysaprobic taxa ) without the most upperstream station. From the data of diatom flora in each sampling station, water qualities were estimated by using Diatom Assemblage Index to organic water pollution(DAIpo), and water quality chart was made using the indices compu ted. River Pollution Index ( RPI_D ), whose value is able to be shown the general degree of pollution of river system, was 29. The value is remarcably lower than those of other rivers in Japan.