Distribution And Sources Of Sterols In Surface Sediments From Bohai Bay And Jiaozhou Bay

Sterols and their derivative compounds during diagenesis are ubiquitously distributed in coastal sediments. Since this class of compounds are produced from specific sources and contain a number of unique structural features, sterol compounds have been used as important biomarkers for identifying sources of organic matter in the ocean especially for the coastal environments, and also for environmental quality and pollution assessment. Both Bohai Bay and Jiaozhou Bay are semi-enclosed coastal embayment where the ocean-land interactions and the impact from anthropogenic influence are very strong. The contamination in the sediments of the two bays is substantial. However, no studies on sterols in sediments of the two bays have been conducted.In this study, we investigated the distribution and composition of sterols in 22 surface sediments collected from Bohai Bay and Jiaozhou Bay. Sedimentary organic matter and C/N radio are measured using CHN Analyzer and concentrations of sterols were quantified using Gas Chromatography-Mass Spectrometer (GCMS).The relatively high C/N ratios of organic matter measured in the sediments indicate the strong influence of terrestrial and anthropogenic sources inputs to Bohai Bay and Jiaozhou Bay. The concentrations of the 8 sterols detected in the surface sediments showed large spatial variations ranging from 0 to 4.303μg/g (dry wt), and Bohai Bay sediments had higher total sterol concentrations (0.287~18.579μg/g) than that (0.084~10.584μg/g) in Jiaozhou Bay. Among the 8 sterols, onlyβ-sitosterol was present in all samples. Sterols such as coprostanol and epicoprostanol which are products of human waste were present at high concentrations in the surface sediments of the coastal regions with large sewage inputs, while the distributions of stigmasterol andβ-sitosterol appeared to be influenced by terrestrial organic matter from river input. Our study suggests that the composition and distribution of sterols in surface sediment can provide useful information for environmental contamination monitoring and pollution assessment in coastal regions.