Abstract
Estuaries plays an important role in the nutrient transport system, but there is only a little knowledge about it. Yamaguchi Bay estuary, which has large tidal marshes, was chosen as the field of this study. By the field work investigation, the following results were obtained; 1) A large ammount of suspended solid is transported upstream during one tidal cycle, under ordinary weather conditions. 2) With this movement, suspended portions of P, N, COD also go upstream, while, soluble portions of them go downstream during one tidal cycle. 3) Movements of chlorophyll-a, suspended solid and C1 ion are different from each other, because the vertical distribution of their concentration and the flowing velocity are localized. 4) Net sedimentation rate of suspended solid in the estuary, caluculated from mass balance or by box model simuration, was 1 to 3 m/day.
