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.

New data are given regarding to groundwater chemistry in the top hydrodynamic zone, including swamp waters, in West Siberian region. It was found that Fe is almost ubiquitous in the examined waters. Its maximal concentrations are typical of depths from a few to 200 m, where gley geochemical medium predominates and high concentrations of dissolved organic matter are recorded. Thermodynamic methods are used for the first time to calculate the equilibrium of different waters with minerals of water-bearing rocks. Groundwater are shown to be in equilibrium with Al and Fe hydroxides; Ca, Mg, Fe carbonates; and clay minerals, including ferruginous. The swamp waters are also in equilibrium with blue iron earth and apatite. The conclusion is made that the sources of Fe, as well as other chemical elements, are minerals of primary aluminum-silicate rocks, with which the waters are never in equilibrium, and which they actively dissolve.

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...

The content and composition of 19 priority polycyclic aromatic hydrocarbons (PAHs) in peat oligotrophic soils (Cryic Histosols) in the northern territories of Western Siberia were analyzed by gas chromatography in chloroform extracts. The content of PAHs in the examined soils varies from 33 to 148 ng/g. Low molecular weight (three-ring) PAHs account for 70–75% of the PAHs composition, while the total share of high molecular weight compounds does not exceed 25%. The latter are mainly represented by four-ring species, their concentrations decreasing in the sequence: fluoranthene > pyrene > chrysene. Cluster analysis (Euclidean index and pair group method) demonstrates the correlation of PAH composition with residual eutrophication and manifestation of soil degradation signs. Principal component analysis shows that phenanthrene, pyrene, and, to a lesser degree, fluoranthene and anthracene display the strongest positive correlation with the first component. The second component correlates with the contents of fluoranthene, fluorene, and naphthalene. The degradation of soil oligotrophic peat horizons accompanied by the appearance of mucky material appears as a decrease in the share of fluoranthene and an increase in the concentration of naphthalene. In oligotrophic peat horizons with the signs of residual eutrophication, the share of fluorene and naphthalene increases along with a decrease in the content of phenanthrene and fluoranthene. The diagnostic ratios identified by principal component analysis—Ant/(Ant + Phe) and Flt/Pyr—suggest a natural (petrogenic) origin of the PAHs in all examined peat soils.

In the conditions of climate warming, the thawing of permafrost can provoke the formation of new thermokarst lakes and subsidence, which facilitates the removal of organic matter from thawed peat into natural waters. Hydrochemical studies of surface waters of the Bolshezemelskaya tundra have demonstrated the exponential dependence of the physicochemical parameters on the size of the water body (peat subsidence, thaw ponds, small lakes, thermokarst lakes). The hydrochemical features of thermokarst lakes of the Bolshezemelskaya tundra are determined by high content of DOC, surface runoff and the thickness of peat deposits. Measurements of concentrations and fluxes of methane showed that all studied water bodies of the Bolshezemelskaya tundra are oversaturated with CH4, and depressions, subsidence, and small water bodies (<100 m2) are characterized by the highest concentrations of DOCs. The contribution of these small reservoirs to the total coverage of the surface of the Bolshezemelskaya tundra area is significant, and their consideration can greatly change the assessment of methane fluxes from the arctic tundra.

The rising concern about the potential toxicity of synthetic gold nanoparticles (AuNPs) in aquatic environments requires a rigorous estimation of physico-chemical parameters of reactions between AuNPs and major freshwater microorganisms. This study addresses the interaction of 10-nm size, positively charged AuNPs with periphytic freshwater diatoms (Eolimna minima). The adsorption experiments on viable cells were performed in 10 mM NaCl and 5 mM NaCl + 5 mM NaHCO₃ solution at a variable pH (3–10), at an AuNPs concentration from 1 µg/L to 10,000 µg/L, and an exposure time from a few minutes to 55 days. Three types of experiments, adsorption as a function of time (kinetics), pH-dependent adsorption edge, and constant-pH “Langmuirian” type isotherms, were conducted. In addition, long-term interactions (days to weeks) of live diatoms (under light and in the darkness) were performed. The adsorption was maximal at a pH from 3 to 6 and sizably decreased at a pH of 6 to 10. Results of adsorption experiments were modeled using a second order kinetic model, a Linear Programming Model, Freundlich isotherm, and a ligand binding equation for one site competition. The adsorption of AuNPs(+) most likely occurred on negatively-charged surface sites of diatom cell walls such as carboxylates or phosphorylates, similar to previously studied metal cations. Under light exposure, the AuNPs were stabilized in aqueous solution in the presence of live cells, probably due to the production of exometabolites by diatoms. The adsorbed amount of AuNPs decreased after several days of reaction, suggesting some AuNPs desorption. In the darkness, the adsorption and assimilation were stronger than under light. Overall, the behavior of positively charged AuNPs at the diatom–aqueous solution interface is similar to that of metal cations, but the affinity of aqueous AuNPs to cell exometabolites is higher, which leads to the stabilization of nanoparticles in solution in the presence of diatoms and their exudates. During photosynthetic activity and the pH rising above 9 in the vicinity of diatom cells, the adsorption of AuNPs strongly decreases, which indicates a decreasing potential toxicity of AuNPs for photosynthesizing cells. The present study demonstrates the efficiency of a thermodynamic and kinetic approach for understanding gold nanoparticles interaction with aquatic freshwater peryphytic microorganisms.