Hydrocarbons in Surface Waters and Sediments of the Southwestern Kara Sea

The article presents data on the content and composition of hydrocarbons (HCs): aliphatic (AHСs) and polycyclic aromatic hydrocarbons (PAHs) in waters and Holocene sediments (bottom grab and undisturbed cores 0–30 cm) of the southwestern Kara Sea (part 1 of cruise 89 of the R/V Akademik Mstislav Keldysh, September 2022). In waters, the distribution of HCs is determined by hydrological factors and their input in fluid flows in shallow waters. In bottom sediments, the distribution of HCs, in contrast to Corg, does not depend on their lithotype, since in the gas-saturated zone, high-molecular HCs are formed along with methane. This leads to an increase in the proportion of AHCs (>1%) and PAHs (> 1 × 10–3%) in Corg, as well as to a change in their distribution and composition in the sedimentary layer. Therefore, in the lower horizons of the sediment sequence, low-molecular alkanes and naphthalenes are formed in the HC composition in the gas-saturated zone and when the redox potential changes.