Abstract
Dissolved silicate (Si(OH)4-Si; DSi) concentration was examined at 38 sampling sites in influent rivers of the northeastern Ariake Bay, and estimated on the basins of a numerical geological map of the sites' watershed. The multiple regression model was used for predicting DSi concentration at the sampling sites using the geological area ratio in their watersheds. The coefficient of determination (R2) obtained was 0.931, indicating that DSi concentration was strongly associated with its geological condition. The geological categories which contribute to DSi concentration in rivers are quaternary volcanic rocks (non-alkali, felsic), volcanic rocks (debris) and quaternary volcanic rocks (non-alkali, pyroclastic flows). This result suggests that the DSi concentration of an arbitrary station in an influent river of the northeastern Ariake Bay can be predicted on the basins of a geological map of the station.
