Abstract
In order to estimate the physical and chemical state of sediments in the Seto Inland Sea, the horizontal distributions of grain size component, organic matter and nutrients in the sediments were investigated. The investigation was carried out 2 times in 1980s (1981-1985) and 1990s (1991-1994) throughout all over the Seto Inland Sea to estimate whether pollution of the sediment improved during past 10 years. The results obtained in 13 sea areas were different in each sea area. It is generalized roughly that the environment of sediment becomes worse in the sea area where the basin has been carried out some development during past 10 years. On the other hand, it hardly changes in the sea area that the basin was developed before the first survey. Although the cut of pollutant loads from the watershed has been performed legally for the last 18 years, the improvement of the sediment environment in this area could hardly be recognized from the results of these survey.
