Use of aliphatic hydrocarbons to infer terrestrial organic matter in coastal marine sediments off China

Sediment samples from the marine systems along the coast of China, covering Yellow Sea, inner shelf of the East China Sea (ECS) and the South China Sea (SCS), were analyzed for n-alkanes and organic carbon. The concentrations of Σn–C15–35 were 120–1680 ng g−1 dry weight with an average of 560 ng g−1. Short-chain n-alkanes (<C21) in Yellow Sea and the SCS were derived from mixed bacteria and planktonic sources, while those in the ECS inner shelf were mainly of planktonic sources. Long-chain n-alkanes (>C21) were mainly derived from terrestrial higher plants. Organic carbon deposited into Yellow Sea and Southeast Hainan within the SCS was mainly of terrestrial (13–110%; mean: 58%) and marine (48–110%; mean: 86%) sources, respectively. On the other hand, organic carbon accumulated in the SCS adjacent to the Pearl River Estuary was derived from both terrestrial and marine sources.