This study reports a synthesis of years-long hydrogeochemical monitoring in northern West Siberia, performed by the Russian Meteorological Service (Rosgidromet) and several academic institutions. Natural factors and intensive human economic activity lead to the disruption of the ecosystems of the northern territories of Western Siberia. The aim of this study is to estimate the background water chemistry parameters in the rivers of northern West Siberia in the beginning of the 21st century. The mean values hydrochemical and geochemical indicators were determined with STATISTICA software, which can be used as background values in assessing the actual and allowable anthropogenic impact on water bodies. We revealed four water chemistry provinces: western Ob Gulf and Ob estuary catchments (I); eastern Ob Gulf and Taz Gulf catchments, except for the Taz River and its tributaries (II); Taz River catchments (III); Yenisei River catchments, right bank (IV). The major-ion chemistry of the sampled river waters records a combination of geological, geomorphological, and hydrological conditions in the four provinces. The features typical of the northern West Siberian Plain are especially prominent in province II, which has the lowest average total of major ions (Σ_mi), the highest chemical oxygen demand (potassium dichromate COD), and the highest contents of Fe and phosphates. The Σ_mi value is the highest in province IV. The river waters from four provinces share similarity in quite high organic contents (both potassium dichromate and permanganate COD), as well as high NH₄⁺ and Fe. The long-term average Σ_mi of the waters is predicted not to change much in the coming one or two decades, though it may decrease slightly in the winter season but increase in the fall and spring time.

Link for citation: Volkova N.A., Ivanova I.S., Sokolov D.S., Kolubaeva Yu. V., Chuikina D.I. Concentrations and sources of polycyclic aromatic hydrocarbons in water and sediments of rivers of northern oil and gas producing territories of Western Siberia. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 4, рр.135-148. In Rus. 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. Ссылка для цитирования: Концентрации и источники полициклических ароматических углеводородов в воде и донных отложениях рек северных нефтегазодобывающих территорий Западной Сибири / Н.А. Волкова, И.С. Иванова, Д.А. Соколов, Ю.В. Колубаева, Д.И. Чуйкина // Известия Томского политехнического университета. Инжиниринг георесурсов. – 2023. – Т. 334. – № 4. – С.135-148. Актуальность. На территории Западной Сибири сосредоточены огромные запасы как пресных вод, так и углеводородов, добыча и разработка которых увеличивается с каждым годом. Нефть является одним из главных факторов экологического риска для природных экосистем Севера. Среди компонентов нефти выделяются полициклические ароматические углеводороды, обладающие...

—: One of the most urgent problems on which current studies of Arctic and subarctic territories are focused is how permafrost thawing can affect organic carbon fluxes and how these fluxes can influence the geochemistry of the surface and ground water. In addition to disturbing the carbon balance, permafrost thawing provokes the release of a significant amount of other chemical elements entering natural waters. The paper presents original data obtained by studying surface water in 2020 in the Yamalo–Nenets Autonomous District, which is situated in the Arctic zone of the Russian Federation. Permafrost is widespread in the study area, as also are facilities of the oil and gas industry. This predetermines the importance of research on the chemical composition of natural water, its formation, and ecological–geochemical status, which are critical aspects for assessing the anthropogenic load and predicting the influence of climate changes on the biogeochemical cycles of chemical elements. In the course of our fieldwork, 47 surface water samples were taken in the basins of the Taz, Pur, Ob, and Nadym rivers: 23 samples from rivers and streams and 24 samples from lakes and thaw depressions. The sampling sites were chosen to as comprehensively as possible cover the lake–stream–river system in the catchment areas of major rivers of the Yamalo–Nenets Autonomous District. The chemical composition of the water samples was analyzed at a certified laboratory using methods conventionally applied in solving such problems. The data were processed using statistical methods, including the principal component analysis (PCA). Data analysis demonstrates that surface water in the study area is ultrafresh, with neutral or weakly alkaline pH values. Hydrocarbonate, calcium, and magnesium ions dominate in the ionic composition of the water, and ammonium contents are high in the waters of the lakes and thaw depressions. In addition, the ammonium concentration strongly positively correlates with the content of dissolved organic carbon (DOC) and the values of chemical oxygen demand (COD) and permanganate index (PI). It was found out that the streams (springs and rivers) differ from the lakes and the water of the thaw depressions in higher concentrations of main ions that are brought to the water mainly by natural factors (these are $${\text{HC}}{{{\text{O}}}_{{\text{3}}}}^{ - }$$ , Ca ²⁺ , Mg ²⁺ , and Na ⁺ ) and higher total dissolved solids (TDS) and pH values. In contrast, the water of the thaw depressions is characterized by the highest concentrations of DOC and the values of other parameters related to organic matter (N– $${\text{N}}{{{\text{H}}}_{4}}^{ + }$$ , COD, and PI). It was shown that the main factors that control the chemical composition of the water are its interaction with organic matter from organic (peat) soil horizons and the mineral components of the underlying rocks and soils. The former factor most significantly impacts the water of the thaw depressions, and the latter one affects mainly the chemical composition of the rivers and streams. The relatively high contents of the chloride and sodium ions in the water of the largest lakes are probably caused by the anthropogenic load.

Relevance. The assessment of the state of natural waters includes the determination of a number of physico-chemical indicators, on the basis of which various indices and classifications are developed. However, they do not take into account a number of pollutants that have a significant impact on the state of the reservoir, for example, polyaromatic hydrocarbons. The article considers some aspects of determining priority pollutants, which include polyaromatic hydrocarbons, according to environmental hazard criteria: toxicity, carcinogenicity, prevalence, frequency of occurrence, source of origin (anthropogenic or natural). Hydrochemical parameters such as pH, dissolved oxygen content, biological oxygen consumption (BPK5), and ion content are taken into account to determine water quality. An attempt was made to assess the impact of polyaromatic hydrocarbons on the ecological state of water bodies and to take into account their contribution to changes in the values of the water pollution index. All these data prove the relevance of the study. Aim. To establish the composition of polyaromatic hydrocarbons in the surface waters of small reservoirs of the Tomsk region to assess anthropogenic load and to show the relationship with the indices of natural water quality. Methods. Extraction, liquid adsorption chromatography, high-performance liquid chromatography, capillary electrophoresis, amperometry, titrimetry. Results. Small lakes of the Tomsk region were studied for the content of 13 polyaromatic hydrocarbons. The authors have carried out the identification by high-performance liquid chromatography with fluorimetric detection. The total content of polyaromatic compounds in the studied surface water samples varies from 0.37 to 0.54 mcg/l. In the polyaromatic hydrocarbons mixture in aqueous samples, there is an increased content of light 2–3 nuclear polyarenes with better solubility (naphthalene, fluorene and phenanthrene), as well as benz[a]anthracene. The content of inorganic components represented by cations and anions does not exceed the maximum permissible concentrations. The water pollution index was calculated; all lakes are moderately polluted, closer to polluted. The paper demonstrates the dependence of the water pollution index coefficient on the content of high-molecular polyaromatic hydrocarbons and the ratio of high-molecular to low-molecular polyaromatic hydrocarbons. It is shown that the higher the value of the water pollution index coefficient, the higher the proportion of difficult-to-oxidize components in surface waters.

Introduction. Iron is a widespread element in groundwater, which is used for domestic and drinking water supply. When using waters from non-centralized sources, deironing of waters, as a rule, is not carried out. When such waters are used for drinking purposes, there is a likely risk of negative effects for public health. Materials and methods. Forty six sources of non-centralized water supply (private wells, water wells, springs) were studied It considered assessing the health risk with oral administration of the components through drinking water into the body. Results. For single samples in the chemical composition of waters there were determined high contents of total hardness, SO42-, Cl-, NO3-. Waters with Fe and Mn concentrations many times higher than the normative values are widespread. The main non-carcinogenic risk is iron and nitrates, which have been identified as warning and high risk levels. For other components, the values of the hazard coefficient are within the range of the minimum and acceptable levels of risk. The probability of occurrence of negative effects for the children’s age group is possible with an iron content of 5 mg/l and more, for an adult - 11 mg/l and more. Limitations. The limitation related to the incomplete route of exposure to chemical components, since only one medium (drinking water) and only one route of exposure (oral exposure) was considered on the risk assessment. This study is also limited by the number of water samples. Conclusion. The health risk associated with high iron content in water has been set for children and adults. For the children’s group (up to 6 years), the risk of developing diseases of non-infectious etiology is significantly higher, than for the adult group, as shown by the results. When iron-containing waters are used for drinking purposes, there is a risk of non-infectious pathologies.