Abstract
Water chemistry was investigated in the main stream and the tributary of Yotsugo River in Siga town, Siga prefecture. Chemical analysis showed that most of inorganic ions were stable and the coefficient of variation of them was less than twenty percents, whereas NO_3^-, dissolved organic carbon (DOC), biochemical oxygen demands and chemical oxygen demands were more changeable. The annual variation of stream water temperature was smaller than that of atmospheric temperature, but the pattern was similar with that of atmospheric temperature. The water temperature was positively correlated with pH, K^+ and DOC concentrations and was negatively correlated with Cl^- concentrations. The discharge was positively correlated with NO_3^- and was negatively correlated with F^- concentrations.
