CONCENTRATIONS AND SOURCES OF POLYCYCLIC AROMATIC HYDROCARBONS IN WATER AND SEDIMENTS OF RIVERS OF NORTHERN OIL AND GAS PRODUCING TERRITORIES OF WESTERN SIBERIA

Abstract

The relevance. Huge reserves of both fresh water and hydrocarbons are concentrated on the territory of Western Siberia, the extraction and development of which is increasing every year. Oil is one of the main environmental risk factors for the natural ecosystems of the North. Among the components of oil, polycyclic aromatic hydrocarbons stand out, which have carcinogenic and mutagenic properties and have a negative impact on natural ecosystems. However, there are quite a lot of sources of these organic pollutants entering the environment, including they can be of both natural and anthropogenic origin. The relevance of the study of the content and composition of these components is caused not only by their toxicity, but also by their resistance to chemical and biological transformation, high migration activity and ability to accumulate in natural environments. The aim of this work was to study the individual composition and distribution of polycyclic aromatic hydrocarbons in water and bottom sediments of rivers, and to identify possible sources of polycyclic aromatic hydrocarbons entering water bodies of the Arctic zone of Western Siberia. Objects: river waters and bottom sediments taken from 8 watercourses in the territory of the Yamalo-Nenets Autonomous Okrug. The objects were chosen in such a way as to cover rivers of various orders within the catchment basins of the main rivers of the Yamalo-Nenets Autonomous Okrug. Methods. The content and individual composition of polycyclic aromatic hydrocarbons in water and bottom sediments of rivers was determined in the laboratory of physical and chemical studies of core and reservoir fluids of the Trofimuk Institute of Petroleum Geology and Geophysics SB RAS (Tomsk) using high-performance liquid chromatography. Statistical processing of the obtained data was carried out using the Microsoft Office Excel and PAST V2.17 software packages. Results. The features of the distribution of polycyclic aromatic hydrocarbons in water and bottom sediments of the rivers of the northern territories of Western Siberia have been studied. The total content of polycyclic aromatic hydrocarbons in the river waters of the YaNAO varies from 292,8 to 1098,0 ng/l. The minimum content of polycyclic aromatic hydrocarbons, represented mainly by low molecular weight compounds (mainly phenanthrene), associated with terrestrial higher vegetation, was established in the Mahanyad-Pusyakha River, which is a tributary of the Nadym River. The highest concentration of the studied compounds, represented mainly by high molecular weight polycyclic aromatic hydrocarbons, was identified in the water of the Apoku-yakha River, tested near the developed deposits and related to the catchment area of ​​the Pur River. The sources of identified compounds in this sample can be associated with both petrogenic and pyrogenic processes. The total content of polycyclic aromatic hydrocarbons in bottom sediments varies from 1900 to 20000 µg/kg, which is due to the presence of not only natural, but also anthropogenic pollution. The maximum concentration of these compounds was found in the bottom sediments of the Apoku-yakha River. Using statistical analysis, indices diagnosing polycyclic aromatic hydrocarbon sources were established: for water – ratios Flt/Pyr and (Pyr+BaP)/(Chr+Phen), for bottom sediments – ratios BaA/(BaA+Chr), Phen/(Phen+Chr ) and (Pyr+BaP)/(Chr+Phen).On the basis of the data obtained, it was found that polycyclic aromatic hydrocarbons enter the rivers, as a rule, from natural sources. The probable sources of polycyclic aromatic hydrocarbons entering bottom sediments can be divided into several groups: oil burning, combustion processes, as well as mixed sources. Polycyclic aromatic hydrocarbons identified in water and bottom sediments of the Apoku-yaha River have an anthropogenic genesis. The environmental assessment of the state of the rivers, based on the calculation of the polycyclic aromatic hydrocarbon hazard coefficient and the bottom accumulation coefficient, indicates a high level of chronic pollution of the studied objects. It was established that the most intense pollution is characteristic of the rivers belonging to the catchment area of the Pur River, where the most active hydrocarbon production takes place.

Keywords

• polycyclic aromatic hydrocarbons
• river waters – bottom sediments
• sources
• high-performance liquid chromatography
• western siberia