Features of hydrocarbon distribution in the coastal zone of the northeastern Black Sea

Data on the content and composition of aliphatic and polycyclic aromatic hydrocarbons in surface water and bottom sediments are reported as compared to the distribution of total organic carbon, suspended particulate matter, lipids, and chlorophyll for the Greater Sochi area and the Gelendzhik and Blue bays. It is established that an influx of oil products leads to the increase of hydrocarbon concentrations in the water and bottom sediments, thus providing the present-day hydrocarbon background. Active transformation of organic matter in the water succession and on the water–bottom interface results in the prevalence of natural components in alkanes in spite of the high hydrocarbon concentrations (119–262 μg/g). The river–seawater mixing zone serves as a geochemical barrier preventing the influx of most pollutants delivered by rivers into open sea.