気仙沼舞根湾海域における水質の推移

摘要

The Great East Earthquake and the following tsunami disaster caused serious impact on coastal environment in Sanriku area, Japan. We have investigated the change and recovery of coastal ecosystem in Kesennuma Bay and Moune Bay after the disaster. It has been monitored heavy metals as a representative of pollutants, nutrient salts, such as nitrogen(N) and phosphate(P), and iron(Fe) in seawater at four sites. Although the results of investigation until spring in 2012 were already reported, we discuss the change of coastal environment based on water quality comprehensively in this manuscript focused on N, P and Fe together with tendency of heavy metal concentrations. It was confirmed again that the concentrations of heavy metals in seawater, such as Cd, Pb, Cr, Zn As and Se, in Kesennuma Bay and Moune Bay were almost under the environmental standards in Japan. Meanwhile, change of N, P and Fe concentrations was small soon after the disaster. We also found that the change of concentrations, especially Fe, corresponds to that of precipitation. This suggests that materials, such as Fe, supplied from the river have large impact on the coastal environment.