Ecological and environmental risks of heavy metals in sediments in Dingzi Bay, South Yellow Sea

As a special geographical location between rivers and oceans, coastal estuaries always face severe heavy metal contaminations, especially in semi-closed bay. In this study, the spatial distribution, chemical fraction, ecological risks, and potential sources of heavy metals (Pb, Cr, Cu, As, Cd, Zn, and Ni) in surface sediments and sediment cores were investigated in Dingzi Bay, Shandong Peninsula. The Igeo values and modified potential ecological risk index (MRI) indicated that Cd and As presented high environmental risks in the surface and sediment cores. The high concentration sites were mainly located in the middle and the mouth of the Dingzi Bay. The source iden-tification indicated that most heavy metals in surface sediments originated from shipping and aquaculture, while As and Ni from industrial pollution. The correlation coefficients showed that high proportion of fine particle, TN, TOC, TP, and AVS in surface sediments could significantly elevate the bioavailability of most heavy metals.

Automated summary

This study investigated the spatial distribution, chemical fraction, ecological risks, and potential sources of heavy metals in surface sediments and sediment cores in Dingzi Bay, Shandong Peninsula. The results showed that Cd and As posed high environmental risks in both surface sediments and sediment cores, with high concentrations mainly found in the middle and the mouth of the bay. The source identification revealed that shipping and aquaculture were the main sources of most heavy metals, while industrial pollution contributed to the levels of As and Ni. Furthermore, the correlation coefficients indicated that the presence of fine particles, total nitrogen, total organic carbon, total phosphorus, and acid-volatile sulfides significantly increased the bioavailability of most heavy metals in surface sediments.