Assessment of heavy metal pollution in sediments of the sea area around the Liandao island of Haizhou bay

The total 21 surface sediment samples were collected in the sea area around Liandao island, which is located in Haizhou bay, Jiangsu province, China. The heavy metals (Cd, Cr, Cu, Pb and Hg) contents and the metal-like arsenic (As) content were determined. The spatial distribution maps of heavy metals and metal-like As were obtained by using Kriging interpolation method. The pollution degree and risk grade of heavy metals and metal-like As were assessed by ground accumulation index and potential ecological risk index respectively. The results were indicated that the average content of heavy metal Cu was higher than the Class 1 standard according to the Marine Sediment Quality (GB 18668-2002). The variation coefficients of heavy metal Cu and Pb were 114.66% and 108.44% respectively. Therefore, they had strong spatial dispersion. The pollution degree of heavy metals and metal-like As ranked from large to small: Cd>Pb>Cu>As>Hg>Cr based on the analysis results of ground accumulation method, in which heavy metal Cd, Cu and Pb were the moderate pollution, As and Hg were mild pollution, and Cr was non-pollution. The overall potential ecological risk level in the sea area of Liandao island reached the medium level. There existed the high ecological risk level of heavy metals and metal-like As in the southern part of Liandao island. Further, the ecological risk of surface sediments was mainly caused by heavy metal Cd.