Concentration, composition, and genesis of hydrocarbons in bottom sediments of the Chernaya River estuarine zone (Sevastopol, the Black Sea)

The “river-sea” geochemical barrier is studied slightly in terms of the variety of pollutants, sedimentation, and degradation. At the same time, problems related to oil pollution, in particular the genesis of hydrocarbons, are almost never covered. This study was dedicated to the origin, concentration, and composition of hydrocarbons in the bottom sediments of the Chernaya River (Black Sea, Crimea) estuarine zone. The features of the marginal filter zone of the river were considered. N-alkanes in the range of C11-C36 were identified in the bottom sediments of the studied water area. It was noted that there was persistent oil pollution (degraded hydrocarbons) in the water area of Sevastopol Bay, adjacent to the confluence of the river. The accumulation of terrestrial material increased as it moved from the river to the sea. The application of various molecular markers displayed the predominately allochthonous origin of the hydrocarbons in the bottom sediments. As a result of the study of molecular markers by using principal component analysis (PCA) and analysis of variance (ANOVA) analysis, three leading factors responsible for hydrocarbon input to the bottom sediments water area were identified. The first one (36.53 % of the total variation) was associated with n-alkanes of natural and anthropogenic input. The second factor (19.52 % variation) was associated with allochthonous organic matter, including petroleum and bacterial destruction. The third factor (10.74 %) was associated with mainly allochthonous routes of organic substances entering the bottom sediments of the water area.