2020 Volume 26 Pages 7-12
The Nigori River is strongly acidic because it has influenced by volcanic activities of Mount Ontake in Japan. In order to understand processes of water quality changes through the mixing of slightly alkaline river, the Denjo River, pH, element concentrations and flow of these rivers were observed. By joining of the Denjo River, pH was raised to near neutrality and Al, Mn, S and Fe concentrations were decreased. In contrast, the contents of these Al, Mn, S and Fe were increased. It is confirmed that at the confluence of the rivers, two effects play roles in changing the element contents. The element contents are changed due to two effects such as the precipitation of elements and the adding of elements from springs and sediments around the rivers. We found that the adding affects contents of Al, Mn, S and Fe more significantly than the precipitation does.
