DISTRIBUTION PATTERN OF HEAVY METALS IN THE SURFACE SEDIMENTS AND ENVIRONMENT QUALITY EVALUATION FOR THE YANGTZE RIVER DELTAIC ECONOMIC ZONE

This paper, based on the 1871 of geochemical data of surface sediments and other geological data, deals with the contents and distribution pattern of heavy metals in the Yangtze River Delta Economic Zone. The results show that, in the surface sediments of the study area, the average contents of As, Cd, Cr, Cu, Hg, Pb, Zn are 8.12×10^-6, 101.53×10^-9, 74.79×10^-6, 19.33×10^-6, 34.87×10^-9, 22.31×10^-6, and 67.13×10^-6 respectively. The higher values of heavy metal elements appear in the area from the Xiangshan to the Yueqing Bay, while the lower values occur along the Jiangsu coast. The comprehensive index method was adopted for environmental quality assessment. It is revealed that the heavily polluted area is located along the channel of the Yangtze River, while slightly polluted area is near the Yangtze River Estuary and the area off Ningbo and Wenzhou. The area along the Jiangsu coat is rather clean.