Sources and Distribution of Heavy Metals in East China Sea Surface Sediments

Abstract

Box cores and surficial sediments collected from the shelf, slope and Okinawa Trough of the East China Sea were analyzed for loss on ignition, and concentration and speciation of aluminium, iron, manganese, lead, cadmium, copper and zinc. in general, concentrations of these metals are higher in the inner shelf and lower in the midshelf, but the highest LOI, cadmium and manganese levels are found in the Okinawa Trough. Spatial distributions of these metals in surficial sediments indicate that the Yangtze River is the major source for materials deposited in the inner shelf. the results of a six-stage sequential leaching experiment indicate that the fluvial input includes natural (e.g., Al and Fe) and anthropogenic (e.g., Pb) materials. the depletion concentration of these metals in the midshelf sediments reflects the dominance (∼ 70%) of coarse, relict sand, while the enrichments in the inner shelf and the Okinawa Trough sediments are due to the fine grained, organic-rich sediments. the speciation of manganese in the sediments of the Okinawa Trough indicates that its distribution is diagentically or hydrothermally controlled.