The role of geochemical barriers in the distribution of flows of polycyclic aromatic hydrocarbons in the mouth areas of seas

The mouth areas of the seas are the most interesting and complex objects for studying the distribution of pollutant flows and the factors of their formation. Different approaches can be used to identify pollutant flows and the role of the geochemical barriers, in particular the analysis of the distribution of marker compounds that most clearly reflect the pollution levels themselves and possible sources of their entry into the components of the aquatic systems. Polycyclic aromatic hydrocarbons (PAHs) are considered as such indicators. We examined the flows of PAHs in the snow cover, the upper and lower parts of the ice cover, the layers of water at different depths, bottom sediments and biota in the river zone, the contact zone of the river and sea waters, and also in the marine part of the mouth of the Northern Dvina (the data of prof. I.A. Nemirovskaya was processed). The use of PAHs indicator ratios made it possible to identify sources of contamination. Analysis of the PAHs concentration coefficients during their transition from one component of the aquatic system to another allowed us to establish patterns of the distribution of hydrocarbon flows and to establish clear differences between the three zones in the near-shore part of the marine aquatic system, in particular, to trace the formation of the "marginal filter". Models of migration and formation of associations of the most persistent compounds within geochemical barriers have been formed. The selective nature of PAHs migration through barriers and their preferential transport on suspended material, including biota, is shown. An estimation is made of the effect of the physico-chemical properties of PAHs on their migration activity and the actual activity of migration and transformation of PAHs complexes in various zones of the marginal filter. Active and passive PAHs have been identified from the point of view of their migration and accumulation activity in the components of the aquatic systems. PAHs compounds are typified by migration conditions through barriers taking into account their basic physico-chemical properties. © SGEM2018.