in order to summarize the environmentalfactors in the River Akagawa. Varimax rotated factor loadings, contribution, cumulative contribution for the first seven PCs obtained by PCA based on the whole data of water and sediment quality were shown in Table 6. (Factor loadings exceeding |0.4| are shown here.) The cumulative contribution of the first seven PCs accounted for more than 80%. The first PC was positively correlated with
dissolved metals. This component may be interpreted as the influence of dissolved metals discharged from the acid mine drainage treatment plant. The second PC was
positively correlated with T-P, SS, TOC and T-N. This component may represent the influence of nutrient and organic matter discharged from green and agricultural spaces and private houses. The third PC was positively correlated with sediment of metals. This component may be interpreted as the precipitation of metals. The fourth PC was positively correlated with pH, chlorophyll a content and sediment of some metals. This component may be considered as the restoration of pH and attached algae on the riverbed.