Modern modes of sediment distribution and the anthropogenic heavy metal pollution record in northeastern Beibu Gulf, south China sea.

During the expedition 908 survey in 2007, 539 seafloor surface sediment samples and two cores were collected over a narrow sector of the northeastern Beibu Gulf, South China Sea. Currently, three dynamic sedimentological processes prevail in the study area: circulation-controlled sand deposition, mud deposition under weak sediment dynamics, and fluvial input. Core A233 from the circulation-controlled sand area, with a 60 cm mixed layer, provides evidence of dynamics disturbance since the mid-Holocene. To reconstruct the anthropogenic heavy metal pollution history, we selected core A146 from the stable mud sector influenced by fluvial input. The dating of core A146 was based on ²¹⁰Pb activity analysis, showing an ~90-year historical record in the upper 40 cm. The heavy metal contamination results showed a generally low pollution level. Nonetheless, increased pollution has happened since the 1950s, especially after 1978 A.D., corresponding to the beginning of China's reform and opening up. • Three dynamic sedimentological processes prevail in the northeastern Beibu Gulf. • Core A146 from the mud sector influenced by fluvial input has good record. • Dynamic after the transgression disturbed core A233 from the sand sector. • The heavy metal contamination results showed a generally low pollution level. • Increased pollution has happened since the 1950s, especially after 1978 A.D. [ABSTRACT FROM AUTHOR]