Distribution and its indication significance of hydrocarbons in surface sediments from Bohai Sea and adjacent area

Concentration, distribution characteristics of total organic carbon (TOC), n-alkanes, total petroleum hydrocarbons (TPH) in surface sediments from Bohai Sea and adjacent area were preliminarily studied in this paper. The indication significance for sources of sedimentary organic matter was discussed. The contents of TOC and n-alkanes ranged from 0.12% to 1.13% and 0.9×10^-6 to 5.1×10^-6, with the average of 0.44% and 2.25×10^-6, respectively. It was indicated, from a combined analysis of C/N ratios, δ¹³C values of bulk organic matter and n-alkanes, that sedimentary organic matter in this area was a mixed marine and terrestrial source. The contents of TPH ranged from 15.2×10^-6 to 65.3×10^-6 with an average of 30.1×10^-6. The highest content of TPH was observed at Bohai bay owing to the significant impact of human activities. Comprehensive analysis of various n-alkane parameters showed that terrestrial contribution of n-alkanes was higher than marine source, and surface sediments of Bohai Sea and adjacent area are generally suffering from petroleum pollution.