Heavy metals distribution and environmental quality assessment for sediments off the southern coast of the Shandong Peninsula, China

A systematic study was conducted on the distribution characteristics of heavy metals and on associated influencing factors in sediments off the southern coast of the Shandong Peninsula, China, based on the results of a heavy metals analysis on 157 surface sediment samples from coastal waters of the study area and on 46 samples from surrounding rivers flowing into the sea. An environmental quality assessment of heavy metals was performed using the Nemerow index. The results show that the distribution characteristics of sediment heavy metals in coastal waters outside of Qingdao can be divided into three classes: (1) Class I - Cr, Cu and Zn, with high-value areas extending from the northeast to the southwest in a banded or tongue-like pattern; (2) Class II - As, Cd and Pb, with high-value areas mainly distributed off the southeastern coast of Mt. Lao; and (3) Class III - Hg only, with high-value areas mainly in the northern area of Jiaozhou Bay. Integrated assessment based on the Nemerow index reveals that heavy metals pollution has occurred in surface sediments in a number of coastal water areas outside of Qingdao. This pollution is mainly found off the southeastern coast of Mt. Lao and in the northeastern section of Jiaozhou Bay. Results show that grain size of surface sediments, surrounding rivers and human activities are the main reasons for the element distribution pattern.