Heavy metal pollution in sediment from the Seto Inland Sea, Japan

Abstract

To discuss the geochemical and environmental behaviors of heavy metals in the Seto Inland Sea which is the largest semi-closed coastal sea in Japan, (1) distributions of heavy metals concerning pollution were examined and (2) mass balances of Zn and Cu were studied by applying a simple box model. Increase in heavy metal contents of core sediments already started in the late 1800s and is considered to be due to human activities. Recently, the pollution of sediment in Osaka Bay which is most contaminated sea area in the Sea, seems to have tended to decrease. In 1980, total sedimentary loads of Cu and Zn over the whole area of the Sea were estimated to be 630 and 3,500 tons/yr, respectively. Further, the sedimentary loads without and with human activities were estimated separately to be, respectively, 320 and 310 tons/yr for Cu and 1,800 and 1,700 tons/yr for Zn. Total inputs of Cu and Zn into the Sea were estimated to be 870 and 4,250 tons/yr and about one half of this being the results of human activities. 70% of the Cu input and 80% of the Zn input are accumulated into the sediments. © 1991.