Distribution of Hydrocarbon Biomarkers with Depth in Marine Sediments in the Area of the Linear Depression of the West Kara Stage

Studies of molecular and hydrocarbon composition of marine sediments provide important information on sedimentary organic matter (OM). In this work, the distribution of hydrocarbons and molecular markers with depth in the sedimentary cover of the linear depression of the West Kara stage was studied. To do this, two sediment cores were sampled during 89th cruise of the R/V Akademik Mstislav Keldysh at site 7444 and at background site 7441. The distribution of n-alkanes was measured by GC-MS analysis, and the distribution patterns of the biomarker indices of sedimentary OM in the marine sediments with depth were determined. It was shown that higher terrestrial vegetation was the dominant source to the sedimentary OM of marine sediments at sites 7444 and 7441. The OM is of low maturity, as follows from its Ts/(Ts + Tm) ratio. According to the values of H31-S/H31-(S + R) and NAR indices, a small constant inflow of oil hydrocarbons occurs in the study area, and a much lower inflow takes place at background site 7441. The distribution of the CPI25–33, TAR, and NAR suggest that hydrocarbons of anthropogenic origin occur in the near-surface layers of 0–15 cm sediment at background site 7441.