Use of Pb Isotopes to Track the Sources of Sediment Metals in Youngil Bay, Korea and Offshore

Metals contaminating coastal sediments can be transported offshore, which is important to consider when devising management plans. This study investigated whether sediments in Youngil Bay contaminated by metals from industries along the coast were transported offshore. Heavy metals, stable Pb isotopes, and 210 Pb ex were analyzed in six box core samples. Two groups of core samples were distinguished based on their metal profiles and Pb isotopes. Core sediments in the southern region (EC8 ~ EC10) originated from the Nakdong River and Chinese rivers, and admixed with metals from nonferrous refineries in Ulsan Bay. Core sediments in the northeastern region samples (EC11 and B05) were the same as in the inner bay sample (EC12), in terms of both metal enrichment and the Pb isotopes in their upper layers (sediments deposited after 1970). This suggests that Pb isotopes can be used to determine whether contaminants in the inner bay are transported offshore, and where they are transported to.