Tracing the source of Pb using stable Pb isotope ratios in sediments of eastern Beibu Gulf, South China Sea

Abstract

We analyze Pb content and Pb isotope ratios in 29 surface sediments and one sediment core from the eastern Beibu Gulf, Southern China. The results indicate that obvious Pb enrichment was limited to the oil and gas exploration area in the central gulf and the mud deposit in the northern gulf. The enrichment of Pb in sediment core A97 started in the 1860s, but a notable drop of Pb content occurred in the 1970s, suggesting variations in human activity. The Pb isotope ratios in sediments were very similar to those in natural sources, except for the sediments near the oil platform, which may be polluted by anthropogenic input. Sediments with relatively high radiogenic Pb isotope compositions may be mainly sourced from northern coast of Beibu Gulf, sediment flux through Qiongzhou Strait, or the Red River, while the coastal zone of western Hainan Island and nearby bottom erosion area produce as minor provenances.

Keywords: Beibu Gulf; Pb isotope; Sediment; Source.