Content and Potential Sources of Pahs and Pcbs in Soils and Bottom Sediments of the Siberian Arctic

Content and Potential Sources of Pahs and Pcbs in Soils and Bottom Sediments of the Siberian Arctic | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Content and Potential Sources of Pahs and Pcbs in Soils and Bottom Sediments of the Siberian Arctic Maria Kulikova, Dmitry Samsonov, Andrey Soromotin This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8209042/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Assessment of environmental pollution in the Arctic is becoming increasingly important in the terms of active industrial development and global climate change. Soils and bottom sediments from the northern regions of Western and Central Siberia were analyzed for persistent organic pollutants including polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). Total concentrations were calculated and trends in the relative distribution of individual PAH and PCB groups were identified in soils and bottom sediments across Arctic subregions defined by CAFF. Potential pollution sources were identified using nonmetric multidimensional scaling (nMDS). The characteristics of lake bottom sediment pollution due to oil and gas production were examined. Total PAHs in soils and bottom sediments of background areas ranged from 0.3 to 112.6 µg/kg dry weight, increasing northward. Total PCBs ranged from 0.2 to 9 µg/kg dry weight, regardless of the subregion. It was shown that PAH contamination occurred predominantly from light 2- and 3-ring compounds. Ordination using non-metric multidimensional scaling showed a decrease in the diversity of PAH compositions in the studied background soils and bottom sediments depending on latitude and distance to the nearest industrial center, which reflects the influence of climate and atmospheric transport. In comparison to background values, lake bottom sediments in the oil and gas production areas showed an increase in the overall content and fraction of heavy PAHs. No significant differences were found in the total content or composition of PCBs in lake bottom sediments from oil and gas production areas compared to background levels. Arctic POP PAH PCB soil bottom sediments pollution Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 1. INTRODUCTION Environmental pollution by persistent organic pollutants (POPs) is a global problem. Polyaromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) occupy a special place among the most toxic and carcinogenic POPs. Due to their high stability, the possibility of long-range atmospheric transport, the ability to bioaccumulate in environmental compartments and food chains even at low concentrations and high toxicity for living organisms, PAHs and PCBs are included in the Protocol on Persistent Organic Pollutants to the Convention on Long-Range Transboundary Air Pollution; PCBs are also included in the Stockholm Convention on Persistent Organic Pollutants (Klyuev 2000 ; Danilina, Kutsenko 2000 ; UNECE 1998; UNEP 2001 ). PAHs are formed during the incomplete combustion of biomass and fossil fuels, volcanic eruptions, and diagenesis, and are also found in crude oil and its refined products (Balmer et al. 2019 ; Khaustov and Redina 2016 ). Thus, PAHs can enter the Arctic environment from both natural and anthropogenic sources with the latter being the most important source of PAH emissions into the environment (Balmer et al. 2019 ; Robertson et al. 1998; Wilcke 2000 ). PAH concentrations in soils generally increase with increasing exposure to industrial, transport, and residential heating (Wilcke 2000 ). Of the several hundred existing PAHs 16 were selected by the U.S. Environmental Protection Agency (USEPA) in the mid-1970s as priorities for monitoring: naphthalene, acenaphthene, acenaphthylene, fluorene, phenanthrene, anthracene, fluoranthene, chrysene, pyrene, benzo(a)anthracene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene, dibenz(a,h)anthracene, indeno(1 2, 3-c, d)pyrene, benzo(g, h, i)perylene (Keith 2014 ). According to calculations of the global emissions of 16 priority PAHs for the period from 1960 to 2008, it peaked at 592,000 tons in 1995 and gradually decreased to 499,000 tons in 2008 (Shen et al. 2013 ). PCBs have been produced since 1929, and their global atmospheric emissions peaked at 3,000 tons per year in the 1970s (Breivik et al. 2007 ; Gałuszka et al. 2020 ). Their wide industrial use is attributed to their thermal and chemical stability, flame retardancy, and dielectric properties (Erickson, Kaley 2011 ). Following restrictions on PCB production and use, atmospheric emissions decreased to several hundred tons per year by the 2010s (Breivik et al. 2007 ; Carlsson et al. 2018 ). Currently, the main sources of PCB pollution are PCB-containing products and waste electrical and electronic equipment recycling plants (Gioia et al. 2011 ; Breivik et al. 2016 ; Gałuszka et al. 2020 ). PCBs can enter the atmosphere through waste incineration, combustion of coal and contaminated biomass, volatilization from polluted water and soil, and certain technological processes, such as paper and pigment production (Eckhardt et al. 2007 ; Gioia et al. 2011 ; Wolska et al. 2014 ; Khairy et al. 2015 ; Breivik et al. 2016 ; Vorkamp, ​​2016; Gałuszka et al. 2020 ). PCB emissions from natural processes are considered to be insignificant compared to anthropogenic sources (Gałuszka et al. 2020 ). Arctic contamination with PAHs and PCBs occurs primarily through long-range atmospheric transport (Balmer et al. 2019 ; Carlsson et al. 2018 ). At high latitudes and low temperatures, deposition prevails over evaporation, resulting in the deposition of atmospheric PAHs and PCBs in Arctic environmental objects (Wania and Mackay 1996 ; Sharpe 2008 ; Balmer et al. 2019 ; Gałuszka et al. 2020 ). More volatile low-molecular PAHs (2–3 rings) and low-chlorinated PCBs (tri- and pentachlorinated biphenyls) are capable of migrating to high latitudes (Wilcke 2000 ; Agrell et al. 1999 ; Gałuszka et al. 2020 ). Although, global PAH emissions are expected to decline, this process may be less evident in the Arctic, as the contribution of local sources may increase in the future as oil production and shipping develop. Future climate change may promote the re-evaporation of PAHs from the environment, which will become a source of secondary emissions into the Arctic atmosphere (Balmer et al. 2019 ). The ban on the production and use of the most hazardous PCBs contributed to a significant decrease in their concentrations in Arctic natural objects up to the 2000s. However, the rate of decline later slowed, likely due to the slow degradation of these substances in Arctic conditions, input from secondary sources, and ongoing anthropogenic emissions (AMAP 2020; Carlsson et al. 2018 ; Gorbacheva and Novikov 2024 ). There is no consensus in the scientific literature on future trends in PCB levels under global climate change, but rising air temperatures will most likely lead to PCB degradation and decrease in their concentrations in the environment (Gałuszka et al. 2020 ). For decades, the north of Western Siberia has been subject to intensive development of oil and gas condensate fields, associated with changes across all environmental compartments (Kukushkin 2017 ; Opekunova et al. 2019 ; Moskovchenko, Romanenko 2020 ). The vast majority of pollutant emissions in the region are associated with fossil fuel extraction, petroleum production, and the transportation of oil, gas, and their refined products through pipelines (Opekunova et al. 2019 ). Active oil and gas development can lead to PAH and PCB contamination of bottom sediments and soils (Opekunov et al. 2012 ). At the same time, the Arctic is home to indigenous peoples of the North, whose livelihoods depend on nomadic reindeer herding. Lichens, an important food resource for reindeer, have the ability to accumulate pollutants, including POPs (Blasco et al. 2006 ; Holma-Suutari et al. 2014 ). Thus, the analysis and monitoring of background levels of PAHs and PCBs in the Arctic are becoming increasingly important due to the need of pollution assessment in the context of active industrial development and global climate change. The study focused on soils and bottom sediments of rivers and lakes in the Arctic zone of Western and Central Siberia, unaffected by oil and gas production, as well as lake bottom sediments located directly within the oil and gas production area. This paper presents the first study of PAH and PCB contents in soil and bottom sediment samples along a latitudinal transect across the Siberian sector of the Arctic. The aim of this study is to assess the content of POPs: 16 priority PAHs and 6 homologous groups of PCBs in soils and bottom sediments of the Siberian Arctic. The objectives of the study were: 1) to assess the total content and relative distribution of PAH and PCB in soils and bottom sediments along a latitudinal gradient in areas not affected by oil and gas production; 2) to identify the sources of PAH and PCB pollution of soils and bottom sediments outside oil and gas production areas; 3) to assess the impact of oil and gas production on PAH and PCB pollution. It is assumed that: 1) the content of PAHs and PCBs in soils and bottom sediments in the north of Western and Central Siberia outside oil and gas production areas increases with latitude. This trend may be driven by less favorable conditions for the decomposition and volatilization of pollutants, as well as by atmospheric transfers from the mining enterprises of the Norilsk industrial complex; 2) since oil and gas production can be an important factor contributing to POPs pollution, the level of pollution and composition of pollutants in the area of ​​active fields differ from those in areas not affected by oil and gas production. 2. MATERIALS AND METHODS The soils and bottom sediments of rivers and lakes in the Ob and Yenisei interfluve were selected for background pollution assessment. Sampling sites were located along a transect crossing the Arctic subregions identified by the Conservation of Arctic Flora and Fauna (CAFF) working group taking into account the bioclimatic features of the territory (Fig. 1 ). In this study, soils and bottom sediments were analyzed within the framework of subregions to reduce variability and increase the statistical power of state and trend assessments. The study area has a temperate and mid-continental climate. According to the physical and geographical zoning, the study area extends from forest (forest-swamp) and forest-tundra regions (Western Siberia) in the south to typical and mountain tundra with glacial-nival complexes (Central Siberia) in the north. The soils are represented by complexes of tundra gley soils, bog tundra soils, soils of spots and cracks in the north, and gley-podzolic soils in the south (National Atlas… 2007). Sampling was conducted in 2005, prior to the commencement of hydrocarbon production in the study area. At the time of sampling, the area was only slightly affected by human activities and was therefore considered as a background site for this study. To assess PAH and PCB contamination from oil and gas production, bottom sediments from seven lakes near the Tazovsky and Zapolyarnoye oil and gas condensate fields were sampled in 2025. The samples were frozen immediately and kept for less than 30 days before analysis. Concentrations of 16 priority PAHs were determined in 92 soil and sediment samples: naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benzo(a)anthracene, chrysene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene, dibenz(a,h) anthracene, indeno(l,2,3-cd) pyrene, and benzo (g,h,i)perylene. ∑16PAHs is the sum of these 16 concentrations. The PCB contents in 86 soil and sediment samples were estimated within homologous groups (di-, tri-, tetra-, penta-, hexa-, and heptachlorinated biphenyls). ∑PCB is defined as the sum of the concentrations of all considered homologous groups of PCBs. Analytical studies were conducted by the scientific center Taifun (Obninsk). PAH analysis was performed by extracting the compounds with dichloromethane, followed by sequential purification of the extracts using activated copper to remove organic sulfur compounds, purification of impurities interfering with the analysis on silica gel columns, and subsequent chromatograph mass spectrometric identification and quantification of individual PAHs. PCB determination involved extraction of the analyzed compounds with dichloromethane in a Soxhlet apparatus. Activated copper and florisil column chromatography were used to purify the extracts. Compound identification was performed using chromatograph mass spectrometry. A system of isotopically labeled surrogate and internal standards, added to the samples at various stages of analysis, was used to control the quality of the analysis. R version 4.3.2 (ggplot2 (3.5.1), vegan (2.6-8), ggalt (0.4.0), ggsci (3.2.0) packages) and MS Excel 2019 were used for statistical processing and data visualization. The Kolmogorov-Smirnov test at a significance level of α = 0.05 supported the hypothesis that the distribution follows the normal law. Since the distributions of most of the variables under consideration did not confirm the hypothesis of normal distribution, the results are presented as medians. Differences between groups were evaluated using the nonparametric Mann-Whitney test at α = 0.05 with Bonferroni correction. Correlations between parameters were estimated using Spearman’s rank correlation coefficient. Ordination methods were performed using nonmetric multidimensional scaling (nMDS). The ANOSIM test was used to analyze similarities in the multivariate structures of the samples. 3. RESULTS 3.1. Total PAH content Table S1 shows the results of the analysis of 16 priority PAHs. One-quarter of the analyzed samples did not contain any of the analyzed PAHs at concentrations above the method’s detection limit. Only samples with PAHs concentrations above the detection limit were included in the calculations. The total concentration of 16 priority PAHs (∑ 16 PAH) varies from 0.3 to 53 µg/kg dry weight in soils and from 0.4 to 113 µg/kg in river and lake sediments. The wide ranges of total PAH concentrations likely reflect both the diversity of natural conditions and anthropogenic impact. The medians of ∑ 16 PAH for the studied soils and bottom sediments were similar and amounted to 15 µg/kg and 17 µg/kg respectively. No statistically significant differences in the total PAH content between the studied soils and bottom sediments were found at a significance level of 0.05. When examining the pollution levels by waterbody type, it was found that the ∑ 16 PAHs in lake bottom sediments ranged from 2.7 to 90.8 µg/kg, and those of rivers – from 0.4 to 112.6 µg/kg. The median ∑ 16 PAHs in lake bottom sediments was 19.3 µg/kg, and 13 µg/kg in river bottom sediments. In terms of the total PAHs, the bottom sediments of the studied rivers and lakes also did not differ statistically significantly at the 0.05 significance level. In the Arctic subregions identified according to CAFF, the statistical significance of the difference in ∑ 16 PAHs in soils (p < 0.05) was revealed the regional patterns of PAH accumulation were taken into account. The median ∑ 16 PAHs in soils increased from 9.7 µg/kg in the subarctic to 15 and 13.7 µg/kg in the low and high Arctic, respectively. In contrast, total PAHs concentrations in bottom sediments did not show statistically significant differences among the Arctic subregions at a significance level of 0.05. Nevertheless, the median ∑ 16 PAHs in bottom sediments increased from 14 µg/kg in the subarctic to 18.5 µg/kg in the low Arctic. 3.2. Relative distribution of PAHs The distribution of PAHs in soils and bottom sediments in terms of the number of rings in molecules in different Arctic subregions is shown (Fig. 2 ). Low molecular weight PAHs (2–3 rings), including naphthalene, acenaphthene, acenaphthylene, fluorene, phenanthrene, anthracene, and fluoranthene, dominate in all the subregions under consideration. Their proportions are 92.7%, 97.8%, and 100% in the subarctic, low Arctic, and high Arctic, respectively. The proportion of two-ring PAHs increases from 80.6% in the subarctic to 90.3% in the high Arctic. Among all the PAHs studied, naphthalene is the predominant compound in the vast majority of samples. The median relative content of high-molecular PAHs (4–6 rings), including chrysene, pyrene, benzo(a)anthracene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene, dibenz(a,h)anthracene, indeno(1,2,3-c,d)pyrene, benzo(g,h,i)perylene, is 7.3% in the subarctic and does not exceed 3.5% in the low and high Arctic. The smallest percentage is occupied by PAHs with 5–6 rings in their structure. 3.3. Total PCB content Table S2 presents the results of the analysis of PCB homologous groups (di-, tri-, tetra-, penta-, hexa-, and heptachlorinated biphenyls). Despite the ban on PCB production, only one-quarter of the analyzed samples contained no PCBs of any of the homologous groups at concentrations above the detection limit of the analytical method. Only those samples with PCB concentrations exceeding the detection limit were considered in the processing. Total PCBs (∑PCBs) varied from 0.2 to 9 µg/kg dry weight in soils and from 0.3 to 3.4 µg/kg in river and lake bottom sediments. The median ∑PCBs of the studied soils and bottom sediments were similar and amounted to 1.1 µg/kg and 1 µg/kg, respectively. No statistically significant differences in ∑PCBs were found between the studied soils and bottom sediments at a significance level of 0.05. It was discovered that the amount of ∑PCBs in lake bottom sediments varies from 0.8 to 3.4 µg/kg, and in rivers – from 0.3 to 2.3 µg/kg depending on the kind of water body. The median ∑PCBs in lake bottom sediments was 1.6 µg/kg, compared with 0.7 µg/kg in river bottom sediments. ∑PCBs in the bottom sediments of the studied lakes were higher than in the bottom sediments of the rivers (p < 0.01). ∑PCBs in soils and bottom sediments do not differ statistically and across the Arctic subregions identified by CAFF at the 0.05 significance level, according to an analysis of regional contamination patterns. Median ∑PCBs in soils were 0.9 1.3, and 0.8 µg/kg in the subarctic, low and high Arctic, respectively. Median ∑PCBs in bottom sediments were 0.9 and 1.0 µg/kg in the subarctic and low Arctic, respectively. 3.4. Relative distribution of PCBs The distribution of homologous groups of PCBs in the Arctic subregions is shown in Fig. 3 . The most common are low-chlorinated di-, tri-, tetra-, and penta-CBs. The distribution of the total content of homologous groups of PCBs in various Arctic subregions showed the widespread dominance of penta- and tetrachlorobiphenyls, accounting for 69 to 79%. When analyzing the distribution of homologous groups, no evidence of PCB fractioning was observed among the subregions. This distribution may reflect the composition of various types of Sovol, a mixture of tetra- and pentachlorobiphenyls formerly produced in the USSR and widely used in electrical equipment (Yanin 1997 ). 3.5. PAH and PCB pollution under the influence of oil and gas production PAH pollution associated with oil and gas production, the main anthropogenic impact in northern Western Siberia, was analyzed using lake bottom sediments located near active hydrocarbon fields on the Taz Peninsula. In these sediments, ∑ 16 PAHs ranged from 90 to 838 µg/kg dry weight. The median ∑ 16 PAHs for bottom sediments was 141 µg/kg dry weight (Table S1 ). The median relative content of low-molecular PAHs (2–3 rings) in the bottom sediments of the sampled lakes was 92%, high-molecular PAHs (4–6 rings) accounted for 8%. Two-ring PAHs were the most represented group, comprising 68.2% of the PAH structure. The main PAH in four of the seven studied lakes is naphthalene, followed by pyrene, phenanthrene, fluorene. The median ∑PCB concentration in lake sediments located near active hydrocarbon fields was 1.1 µg/kg dry weight (Table S2). The distribution of the total content of homologous PCB groups showed the dominance of pentachlorobiphenyls, accounting for 50 to 64%. 4. DISCUSSION 4.1. Total content and relative distribution of PAHs The concentration of benzo(a)pyrene in the sampled soils does not exceed the established permissible exposure limit of 20 µg/kg (Sanitary Regulations and Standards 1.2.3685-21). For other PAHs, maximum permissible concentrations and approximate permissible limits have not been established in the Russian Federation. The concentrations of individual compounds (benzo(a)anthracene, benzo(b)fluoranthene, benzo(k)fluoranthene, dibenz(a,h)anthracene, indeno(1,2,3-cd)pyrene, phenanthrene, pyrene) in the studied soils are several times lower than the Canadian standards for agricultural soils, which specify an upper limit of 100 µg/kg for individual PAH compounds (Canadian Soil Quality Guidelines… 2007). According to the classification proposed by Maliszewska-Kordybach ( 1996 ), the studied soils are classified as “unpolluted” based on the total PAH content (∑ 16 PAH < 200 µg/kg). The sums of concentrations of 14 individual PAHs in the studied soils (∑ 14 PAH = 0.3–53 µg/kg) are comparable to those in polar soils of the Russian Arctic not affected by anthropogenic influence (∑ 14 PAH = 5.2-147.1 µg/kg; Abakumov et al. 2015 ). When considering the sum of 16 PAHs, the studied soils (from 0.3 to 53 µg/kg) are similar to the background PAH contents in the illuvial horizons of soils in the north of Western Siberia (from 10 to 70 µg/kg; Opekunova et al. 2022 ) and are close to the average level of contamination of Urengoy tundra soils (55 µg/kg; Opekunov et al. 2012 ). The concentrations of 16 PAHs in the bottom sediments of rivers and lakes in the studied area (∑16PAHs no more than 112.6 µg/kg) are comparable to those in the pelitic sediments of the shelf of the Kara Sea, the Gulf of Ob and the Yenisei Gulf (∑ 14 PAHs no more than 121.4 µg/g; Dahle et al. 2003 ). The total content of 12 PAHs in the bottom sediments of the studied rivers (∑ 12 PAHs ≤ 112.6 µg/kg) is dozen times lower than in the bottom sediments of rivers in the Yamalo-Nenets Autonomous Okrug (∑ 12 PAHs = 1,973.9–18,504 µg/kg), which are subjected to intense anthropogenic impact of oil and gas production (Volkova et al. 2023 ). The Spearman correlation coefficient between ∑ 16 PAHs and the sampling-site latitude was 0.6 at p < 0.01. Temperature largely determines the concentration of easily decomposable and most abundant naphthalene in the studied samples (Wilcke, Amelung 2000 ). The Spearman correlation coefficient between ∑ 16 PAHs and the distance from the sampling site to the nearest industrial center (Norilsk) was − 0.5 at p < 0.01. It is also worth noting the predominance of south-easter winds in the Norilsk area (Fig. 1 ), which confirms the influence of the Norilsk industrial complex on the formation of pollution in the study area. Thus, an increase in the content of 16 PAHs with latitude may be due to the presence of a large industrial center and a harsh climate, which creates less favorable conditions for the decomposition and volatilization of PAHs. Natural organochlorines decomposition is decelerated in cold climate providing prolonged occurrence of these compounds unchanged (AMAP 2020). Low-molecular-weight PAHs are most abundant in the study area. A decline in the proportion of volatile and readily degradable PAHs with increasing mean annual air temperature was previously noted by Wilcke and Amelung ( 2000 ). Naphthalene, which predominates in the vast majority of samples, originates from both natural and anthropogenic processes. A global analysis of PAH distribution in 27 regions revealed a predominance of naphthalene, phenanthrene, and perylene over high-molecular-weight PAHs in background soils with low total PAH concentrations (Wilcke 2007 ). The predominance of light PAHs has also been reported in background Arctic soils (Abakumov et al. 2015 ). The tendency toward an increase in the proportion of two-ring PAH compounds in soils and bottom sediments of the high-latitude Arctic is observed due to the previously described phenomenon of fractionation as a result of long-range atmospheric transport of more volatile low-molecular compounds, in particular naphthalene (Wania and Mackay 1996 ; Wilcke and Amelung 2000 ). Among the high-molecular PAHs in the studied samples, chrysene and benzo(b)fluoranthene were most often predominant, both can originate from anthropogenic as well as natural sources (Khaustov and Redina 2016 ). 4.2. Total content and relative distribution of PCBs PCB levels in the sampled soils do not exceed the permissible exposure limit of 20 µg/kg established in the Russian Federation (Sanitary Regulations and Standards 1.2.3685-21). The maximum PCB concentrations in the sampled soils and bottom sediments are dozen times lower than the Canadian standard for agricultural soils, set at 500 µg/kg (Canadian Soil Quality Guidelines… 2007). The sum of dichlorinated biphenyl concentrations in the studied soils (0.03–0.37 µg/kg) are consistent with those reported for soils of the oil and gas production areas of the Yamalo-Nenets Autonomous Okrug (∑ 3 PCB = 0.09–0.74 µg/kg; Opekunov et al. 2012 ). The PCB content in the bottom sediments of the sampled lakes (∑PCB = 0.8–3.4 µg/kg) is comparable to the sum of 10 PCB congeners in the bottom sediments of lakes in the Arctic zone of Russia (∑ 10 PCB = 0.38–7.9 µg/kg; Skotvold, Savinov 2003 ). In contrast to ∑ 16 PAHs no significant correlations were found between ∑PCBs and the geographic parameters examined (latitude and longitude of sampling, distance to the nearest industrial center – Norilsk). Significant increase of tetra-, pentachlorobiphenyls contents to the north of 60° N was registered before in Siberia (Mamontova et al. 2016 ). A comparison of the percentage distribution of homologous PCB homologous groups in the studied soils and bottom sediments with those in the Sovol (USSR, GSO 7821 − 2000) and Aroсlor (USA, Toxicological Profile for Polychlorinated Biphenyls (PCBs) commercial mixtures showed that the studied samples were mostly contaminated with Sovol (Fig. 4 ). The calculated Spearman correlation coefficients also showed a high similarity between the composition of the contaminants and the composition of Sovol (r s = 0.705-1.000, p < 0.05). Only 5 of 86 samples showed no statistically significant correlation with any of the commercial PCB mixtures analyzed. 4.3. Sources of PAHs and PCBs Possible sources of background PAH pollution were assessed by ordinating the sampled stations based on their PAH composition using non-metric multidimensional scaling (nMDS, Fig. 5 ). For analytes with concentrations below the detection limit of the method, half of their detection limits were adopted. The ANOSIM test showed differences (R = 0.27, p < 0.0001) in the PAH composition among different subregions. The pattern allows us to assume the influence of mixed emissions from various pollution sources, combusted materials and combustion conditions in the subarctic due to the large scattering of the studied stations along the PAH distribution profile. Atmospheric transport can also contribute to systematic differences in PAH distribution profiles (Wilcke 2007 ). The higher similarity in PAH composition among sampled sites in northern regions may result from both a smaller number of sources, materials, and combustion conditions, and PAH fractionation due to atmospheric transport of volatile compounds on a local scale. Inclusion of geographic (latitude and longitude of sampling, distance to the nearest industrial center – Norilsk) and chemical (pH, salinity as a sum of SO 4 2− , Cl − , NO 3 − , Ca 2+ , Na + , K + , Mg 2+ ions in soil/bottom sediments) parameters in the ordination showed that differences in the PAH composition of the studied soils and bottom sediments are affected by the sampling latitude (r 2 = 0.55, p < 0.001) and the distance to the nearest large industrial center (r 2 = 0.45, p < 0.001), which reflects the influence of atmospheric transport of PAHs. To determine the origin of PAH pollution, commonly used isomeric ratios of fluoranthene to pyrene (Flt/Py) and phenanthrene to anthracene (Phe/An) concentrations were also considered. Most of the studied samples were characterized by Flt/Py > 1 and Phe/An < 10 values, indicating the dominant influence of pyrogenic anthropogenic sources of PAHs (Soclo et al. 2000). No significant correlations were found between ∑ 16 PAHs and ∑PCBs in soils and bottom sediments, which may indicate different sources of their input (Wolska et al. 2014 ). According to the ANOSIM test, the composition of PCBs in soils and bottom sediments does not differ significantly among Arctic subregions. Unlike PAHs, climate and distance from major industrial centers have a less pronounced effect on PCB distribution. The nature of PCB contamination of the studied soils and bottom sediments may reflect general background contamination resulting from the widespread use of Sovol in the former USSR. 4.4. PAH and PCB pollution under the influence of oil and gas production Total PAH concentrations in bottom sediments near active hydrocarbon fields differ statistically significantly from bottom sediments located in lakes in background areas (p < 0.05). The median ∑ 16 PAH in bottom lake sediments from the oil and gas production area (141 µg/kg dry weight) is 7 times higher than the value in bottom lake sediments in the studied background areas (19 µg/kg dry weight). A number of features were noted in the PAH structure. Low-molecular-weight PAHs (2–3 rings), similar to background areas, were the most abundant in the sampled lakes. The median relative content of high-molecular-weight PAHs in the bottom sediments of the studied lakes (8%) was higher than in the bottom sediments of the sampled background subarctic lakes (less than 3.5%). This indicates that anthropogenic impact from oil and gas production increases the proportion of of heavy PAHs along with the total content. It has previously been shown that the PAH content in river bottom sediments increases under the influence of intensive hydrocarbon production (Volkova et al. 2023 ). In addition, an increase in the proportion of heavy PAHs, which are typically technogenic, can serve as a marker of anthropogenic impact (Abakumov et al. 2015 ). The median ∑PCB for bottom sediments of lakes near hydrocarbon fields (1.1 µg/kg dry weight) is comparable to ∑PCB in bottom sediments of the sampled background subarctic lakes (0.91 µg/kg dry weight). In terms of the relative distribution of homologous groups the composition of contaminants, when compared to the background sites, is similar to the composition of the widely used Sovol: the calculation of Spearman's correlation coefficients showed a strong correlation (r s = 0.803-1.000, p < 0.01) with its composition (USSR, GSO 7821 − 2000). Thus, hydrocarbon production did not significantly affect the level and composition of PCB contaminants. 5. CONCLUSION Arctic soils and bottom sediments were analyzed along a latitudinal gradient for PAH and PCB content, ranging from 0.3 to 112.6 µg/kg and 0.2 to 9 µg/kg dry weight, respectively. The data obtained made it possible to characterize the formation of background PAH and PCB pollution in the study area and can be used for further monitoring studies. The hypothesis that PAH and PCB concentrations increase with latitude in the north of Western and Central Siberia outside of oil and gas production areas was partially confirmed for PAHs. The prevailing conditions for contaminant accumulation and degradation, along with proximity to a major industrial center, contributed to the increased total concentrations of 16 priority PAHs. It was shown that the studied soils and bottom sediments are largely contaminated with low-molecular-weight PAHs, while the contaminant composition varies depending on latitude and distance to the nearest industrial center, reflecting the influence of climate and atmospheric transport. The hypothesis was not confirmed for PCBs, whose total amount and composition in background soils and bottom sediments of the subregions studied do not differ significantly, indicating that climate and distance to a major industrial center have a less pronounced effect on PCB pollution. The most common pollutants were low-chlorinated di-, tri-, tetra-, and penta-CBs. Sorting samples by on PCB composition revealed that the studied background samples were predominantly contaminated with Sovol. The second hypothesis regarding POP contamination related to oil and gas production was partially confirmed for PAHs. It was shown that in lake bottom sediments in oil and gas production areas, an increase in total PAH content was accompanied by a higher proportion of heavy PAHs compared to background samples. At the same time, oil and gas production activities did not significantly affect either the total PCB content or their composition. Declarations Funding The study was supported by the Russian Science Foundation Project No. 24-16-00163 (data analysis and statistical processing, paper writing). Competing Interests ☐ The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. ☒ The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Andrei V. Soromotin reports financial support was provided by the Russian Science Foundation (project No. 24-16-00163) Author contributions Conceptualization: Soromotin Andrey Vladimirovich Methodology: Kulikova Maria Andreevna, Samsonov Dmitry Petrovich Formal analysis and investigation: Soromotin Andrey Vladimirovich, Kulikova Maria Andreevna Writing – original draft preparation: Kulikova Maria Andreevna Writing – review and editing: Soromotin Andrey Vladimirovich Funding acquisition: Soromotin Andrey Vladimirovich Resources: Soromotin Andrey Vladimirovich Supervision: Soromotin Andrey Vladimirovich Data availability The datasets generated and analyzed during the current study are available in the Mendeley Data repository, https://data.mendeley.com/datasets/zjk9vmnzv8/1 References Abakumov EV, Tomashunas VM, Lodygin ED, Gabov DN, Sokolov VT, Krylenkov VA, Kirtsideli IY (2015) Policiklicheskie aromaticheskie uglevodorody v pochvah ostrovov i poberezhij Rossijskogo sektora Arktiki [Polycyclic aromatic hydrocarbons in soils of islands and coasts of Russian sector of Arctic]. Eurasian Soil Science 1433-1438. https://doi.org/10.7868/S0032180X15120023 Agrell C, Okla L, Larsson P, Backe C, Wania F (1999) Evidence of latitudinal fractionation of polychlorinated biphenyl congeners along the Baltic Sea region. Environmental science & technology 33(8):1149-1156. AMAP Assessment 2020: POPs and Chemicals of Emerging Arctic Concern: Influence of Climate Change 2021. Arctic Monitoring and Assessment Programme (AMAP), Oslo, Norway Balmer JE, Hung H, Yu Y, Letcher RJ, Muir DC (2019) Sources and environmental fate of pyrogenic polycyclic aromatic hydrocarbons (PAHs) in the Arctic. Emerging Contaminants 5:128-142. https://doi.org/10.1016/j.emcon.2019.04.002 Blasco M, Domeño C, Nerín C (2006) Use of lichens as pollution biomonitors in remote areas: comparison of PAHs extracted from lichens and atmospheric particles sampled in and around the Somport tunnel (Pyrenees). Environmental science & technology 40(20):6384-6391. https://doi.org/10.1021/es0601484 Breivik K, Armitage JM, Wania F, Sweetman AJ, Jones KC (2016) Tracking the global distribution of persistent organic pollutants accounting for E-waste exports to developing regions. Environmental Science & Technology 50(2):798–805. https://doi.org/10.1021/acs.est.5b04226 Breivik K, Sweetman A, Pacyna JM, Jones KC (2007) Towards a global historical emission inventory for selected PCB congeners: A mass balance approach: 3: An update. Science of the Total Environment 377(2):296–307. https://doi.org/10.1016/j.scitotenv.2007.02.026 Canadian Soil Quality Guidelines for the Protection of Environmental and Human Health, Summary Tables, Update 7.0 (2007) https://support.esdat.net/Environmental%20Standards/canada/soil/rev_soil_summary_tbl_7.0_e.pdf. Accessed 10 October 2025 Carlsson P, Breivik K, Brorström-Lundén E, Cousins I, Christensen J, Grimalt JO, Halsall C, Kallenborn R, Abass K, Lammel G, Munthe J, MacLeod M, Odland JØ, Pawlak J, Rautio A, Reiersen LO, Schlabach M, Stemmler I, Wilson S, Wöhrnschimmel H (2018) Polychlorinated biphenyls (PCBs) as sentinels for the elucidation of Arctic environmental change processes: A comprehensive review combined with ArcRisk project results. Environmental Science and Pollution Research 25(23):22499–22528. https://doi.org/10.1007/s11356-018-2625-7 Dahle S, Savinov VM, Matishov GG, Evenset A, Næs K (2003) Polycyclic aromatic hydrocarbons (PAHs) in bottom sediments of the Kara Sea shelf, Gulf of Ob and Yenisei Bay. Science of the Total Environment 306(1-3):57-71. https://doi.org/10.1016/S0048-9697(02)00484-9 Danilina AE, Kutsenko VV (2000) Politika i upravlenie PHB v Rossii [Policy and Management of PCBs in Russia]. Polihlorirovannye bifenily. Supertoksikanty ХХI veka: Informacionnyj vypusk 5:5-13. Eckhardt S, Breivik K, Manø S, Stohl A (2007) Record high peaks in PCB concentrations in the Arctic atmosphere due to long-range transport of biomass burning emissions. Atmospheric Chemistry and Physics 7(17):4527–4536. https://doi.org/10.5194/acp-7-4527-2007 Erickson MD, Kaley RG (2011) Applications of polychlorinated biphenyls. Environmental Science and Pollution Research. 18:135-151. https://doi.org/10.1007/s11356-010-0392-1 Gałuszka A, Migaszewski ZM, Rose NL (2020) A consideration of polychlorinated biphenyls as a chemostratigraphic marker of the Anthropocene. The Anthropocene Review 7(2):138-158. https://doi.org/10.1177/2053019620916488 Gioia R, Eckhardt S, Breivik K, Jaward FM, Prieto A, Nizzetto L, Jones KC (2011) Evidence for major emissions of PCBs in the West African Region. Environ. Sci. Technol. 45:1349–1355. https://doi.org/10.1021/es1025239 Gorbacheva EA, Novikov MA (2024) Hlororganicheskie soedineniya v atlanticheskoj treske (Gadus morhua) i mor skoj kambale (Pleuronectes platessa) Barenceva morya [Organochlorine compounds in Atlantic cod (Gadus morhua) and flounder (Pleuronectes platessa) of the Barents Sea]. Arctic: ecology and economy 14(4):562-574. https://doi.org/10.25283/2223-4594-2024-4-562-574. Holma-Suutari A, Ruokojärvi P, Laaksonen S, Kiviranta H, Nieminen M, Viluksela M, Hallikainen A (2014) Persistent organic pollutant levels in semi-domesticated reindeer (Rangifer tarandus tarandus L.), feed, lichen, blood, milk, placenta, foetus and calf. Science of the total Environment 476:125-135. https://doi.org/10.1016/j.scitotenv.2013.12.109 Keith LH (2014) The Source of U.S. EPA’s Sixteen PAH Priority Pollutants. Polycyclic Aromatic Compounds 35(2-4):147–160. https://doi.org/10.1080/10406638.2014.892886 Khairy M, Muir D, Teixeira C, Lohmann R (2015) Spatial distribution, air-water fugacity ratios and source apportionment of polychlorinated biphenyls in the lower Great Lakes Basin. Environmental Science & Technology 49(23):13787–13797. https://doi.org/10.1021/acs.est.5b00186 Haustov AP, Redina MM (2016) Indikatornye sootnosheniya koncentracij policiklicheskih aromaticheskih uglevodorodov dlya geoekologicheskih issledovanij prirodnyh i tekhnogennyh ob"ektov [Indicator ratios of concentrations of polycyclic aromatic hydrocarbons for geoecological studies of natural and man-made objects]. Geoèkologiâ 3:220-233 Klyuev NA (2000) Ekologo-analiticheskij kontrol' stojkih organicheskih zagryaznenij v okruzhayushchej srede [Ecological and analytical control of persistent organic pollutants in the environment]. Dzhejms, Moscow. Kukushkin SY (2017) Indikatory antropogennoj nagruzki na prirodno-territorial'nye kompleksy pri osvoenii neftegazokondensatnyh mestorozhdenij severa Zapadnoj Sibiri [Indicators of anthropogenic load on natural-territorial complexes during oil and gas condensate fields development in the north of Western Siberia]. Dissertation, Russian State Hydrometeorological University Maliszewska-Kordybach B (1996) Polycyclic aromatic hydrocarbons in agricultural soils in Poland: preliminary proposals for criteria to evaluate the level of soil contamination. Applied Geochemistry 11(1-2):121-127. https://doi.org/10.1016/0883-2927(95)00076-3 Mamontova EA, Tarasova EN, Mamontov AA, Kuzmin MI (2016) The effect of long-range atmospheric transport of organochlorine compounds by soil studies from Mongolia to the Arctic. Doklady Earth Sciences 466(2):169-172. https://doi.org/10.1134/S1028334X16020148. Moskovchenko DV, Romanenko EA (2020) Osobennosti elementnogo sostava pochv Pur-Tazovskogo mezhdurech'ya [Features of the elemental composition of soils of the Pur-Taz interfluve]. Dokuchaev Soil Bulletin 103:51-84. https://doi.org/10.19047/0136-1694-2020-103-51-84 Nacional'nyj atlas Rossii. Tom 2. Priroda. Ekologiya. [National Atlas of Russia. Volume 2. Nature. Ecology] (2007) Kartografiya, Moscow Opekunov AY, Opekunova MG, Kukushkin SY, Ganul AG (2012) Ocenka ekologicheskogo sostoyaniya prirodnoj sredy rajonov dobychi nefti i gaza v YANAO [Assessment of natural environment ecological state of oil and gas production areas in Yamalo-Nenets Autonomous Okrug]. Vestnik of Saint Petersburg University. Earth Sciences 4:87-101 Opekunova MG, Opekunov AY, Kukushkin SY, Lisenkov SA, Vlasov SV, Somov VV (2022) Zagryaznenie pochv severa Zapadnoj Sibiri neftyanymi i policiklicheskimi aromaticheskimi uglevodorodami: raspredelenie i ocenka ekologicheskogo riska [Pollution of soils in the north of Western Siberia with oil and polycyclic aromatic hydrocarbons: distribution and assessment of environmental risk]. Eurasian Soil Science 11:1442-1460. https://doi.org/10.31857/S0032180X22110107 Opekunova MG, Opekunov AY, Kukushkin CY, Ganul AG (2019) Fonovoe soderzhanie himicheskih elementov v pochvah i donnyh osadkah severa Zapadnoj Sibiri [Background content of chemical elements in soils and bottom sediments of the north of Western Siberia]. Eurasian Soil Science 4:422–439. https://doi.org/10.1134/S0032180X19020114 Robertson A (1998) Petroleum hydrocarbons. AMAP Assessment Report: Arctic Pollution Issues. Arctic Monitoring and Assessment Programme (AMAP), Oslo, Norway, pp 661-716 Sharpe M (2008) 10th anniversary lecture: looking to the future of POPs. Journal of Environmental Monitoring 10(11):1259-1260. https://doi.org/10.1039/B815267P Shen H, Huang Y, Wang R, Zhu D, Li W, Shen G, Wang B, Zhang Y, Chen Y, Lu Y, Chen H, Li T, Sun K, Li B, Liu W, Liu J, Tao S (2013) Global atmospheric emissions of polycyclic aromatic hydrocarbons from 1960 to 2008 and future predictions. Environmental science & technology 47(12):6415-6424. https://doi.org/10.1021/es400857z Skotvold T, Savinov V (2003) Regional distribution of PCBs and presence of technical PCB mixtures in sediments from Norwegian and Russian Arctic Lakes. Science of the total environment 306(1-3):85-97. https://doi.org/10.1016/S0048-9697(02)00486-2. NCBI 2025. Toxicological Profile for Polychlorinated Biphenyls (PCBs). Atlanta (GA): Agency for Toxic Substances and Disease Registry (US); 2000 Nov. 4, CHEMICAL AND PHYSICAL INFORMATION. https://www.ncbi.nlm.nih.gov/books/NBK587431/. Accessed 20 August 2025 UNECE 2025. The 1998 Aarhus Protocol on Persistent Organic Pollutants (POPs). https://unece.org/environmental-policy/air/protocol-persistent-organic-pollutants-pops. Accessed 13 July 2025 UNEP 2001. Stockholm Convention on POPs, Text and Annexes, Interim Secretariat for the Stockholm Convention on Persistent Organic Pollutants. Geneva: UNEP Chemicals. https://chm.pops.int/portals/0/repository/convention_text/unep-pops-cop-convtext-full.english.pdf. Accessed 13 July 2025 Volkova NA, Ivanova IS, Sokolov DA, Kolubaeva YV, Chujkina DI (2023) Koncentracii i istochniki policiklicheskih aromaticheskih uglevodorodov v vode i donnyh otlozheniyah rek severnyh neftegazodobyvayushchih territorij Zapadnoj Sibiri [Concentrations and sources of polycyclic aromatic hydrocarbons in water and bottom sediments of rivers in the northern oil and gas producing areas of Western Siberia]. Bulletin of the Tomsk Polytechnic University. Geo Assets Engineering 334(4):135-148. https://doi.org/10.18799/24131830/2023/4/3924 Vorkamp K (2016) An overlooked environmental issue? A review of the inadvertent formation of PCB-11 and other PCB congeners and their occurrence in consumer products and in the environment. Science of the Total Environment 541:1463-1476. https://doi.org/10.1016/j.scitotenv.2015.10.019 Wania F, Mackay D (1996) Peer reviewed: tracking the distribution of persistent organic pollutants. Environmental science & technology 30(9):390A-396A. https://doi.org/10.1021/es962399q Wilcke W (2007) Global patterns of polycyclic aromatic hydrocarbons (PAHs) in soil. Geoderma 141(3-4):157-166. https://doi.org/10.1016/j.geoderma.2007.07.007 Wilcke W (2000) Synopsis polycyclic aromatic hydrocarbons (PAHs) in soil—a review. Journal of plant nutrition and soil science 163(3):229-248. https://doi.org/10.1002/1522-2624(200006)163:3%3C229::AID-JPLN229%3E3.0.CO;2-6 Wilcke W, Amelung W (2000) Persistent organic pollutants in native grassland soils along a climosequence in North America. Soil Science Society of America Journal 64(6):2140-2148. https://doi.org/10.2136/sssaj2000.6462140x Wolska L, Mechlińska A, Rogowska J, Namieśnik J (2014) Polychlorinated biphenyls (PCBs) in bottom sediments: Identification of sources. Chemosphere 111:151-156. https://doi.org/10.1016/j.chemosphere.2014.03.025 Yanin EP (1997) Polihlorirovannye bifenily v okruzhayushchej srede (ekologo-gigienicheskie aspekty) [Polychlorinated biphenyls in the environment (ecological and hygienic aspects)], Dialog MGU, Moscow Supplementary Files Supplementary.xlsx Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8209042","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":554553546,"identity":"5902113a-2748-47db-8454-212126a95872","order_by":0,"name":"Maria Kulikova","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAyUlEQVRIiWNgGAWjYJACxgYGCx4JEOsDCVokwFoYZzAYEK+FAaSFmYcYLboNzA8YZ7ZJyEi29xh+tm37E23OwPtMAp8WswNsBowb2yR4pHnOGEvnthnk7mxgNyOghcGA8SFQi5xEWgJYy4YDbGwEtLB/gGlJ/m1JnBYeqMMkko9JMxKl5TBPwcEZ5yR4JHsOH7PsOWecu+EwG7MFXi3H2zc+7CmzsZc43th840eZXO6G422MN/BpYWBmYDiAITIKRsEoGAWjgEIAAMlVQIC9/h27AAAAAElFTkSuQmCC","orcid":"https://orcid.org/0009-0004-0916-0067","institution":"Tyumen State University: Tumenskij gosudarstvennyj universitet","correspondingAuthor":true,"prefix":"","firstName":"Maria","middleName":"","lastName":"Kulikova","suffix":""},{"id":554553547,"identity":"225fe8d9-8e0f-4362-8d59-13aab7cc4ab5","order_by":1,"name":"Dmitry Samsonov","email":"","orcid":"","institution":"Taifun Research and Production Association","correspondingAuthor":false,"prefix":"","firstName":"Dmitry","middleName":"","lastName":"Samsonov","suffix":""},{"id":554553548,"identity":"5d91a66c-c8ae-4bc0-8bec-e5d440af047f","order_by":2,"name":"Andrey Soromotin","email":"","orcid":"","institution":"Tyumen State University: Tumenskij gosudarstvennyj universitet","correspondingAuthor":false,"prefix":"","firstName":"Andrey","middleName":"","lastName":"Soromotin","suffix":""}],"badges":[],"createdAt":"2025-11-26 05:59:24","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8209042/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8209042/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":97536890,"identity":"dc6d3066-717a-4136-b59b-a61140a63f71","added_by":"auto","created_at":"2025-12-05 14:30:52","extension":"jpg","order_by":0,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":1215564,"visible":true,"origin":"","legend":"","description":"","filename":"Fig.1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8209042/v1/e9aaa3cc83155cc2c6f54f5d.jpg"},{"id":97670986,"identity":"b0ad5d00-7b3c-4170-9584-e8d416c8d0c3","added_by":"auto","created_at":"2025-12-08 09:31:41","extension":"jpg","order_by":1,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":577828,"visible":true,"origin":"","legend":"","description":"","filename":"Fig.2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8209042/v1/5c290e85740e9f80a4fde23a.jpg"},{"id":97536888,"identity":"939131ea-2258-4bd4-a0a9-b5c176103449","added_by":"auto","created_at":"2025-12-05 14:30:52","extension":"jpg","order_by":3,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":674651,"visible":true,"origin":"","legend":"","description":"","filename":"Fig.3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8209042/v1/fb1b4fe9eb9c87bf794631e4.jpg"},{"id":97536893,"identity":"19ebfc0e-3537-499c-995e-18e580e033ce","added_by":"auto","created_at":"2025-12-05 14:30:52","extension":"jpg","order_by":4,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":477879,"visible":true,"origin":"","legend":"","description":"","filename":"Fig.4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8209042/v1/e7fe0662363b023f8652e195.jpg"},{"id":97671735,"identity":"57b57311-3835-4058-9d26-d0f296162f05","added_by":"auto","created_at":"2025-12-08 09:33:01","extension":"jpg","order_by":5,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":970436,"visible":true,"origin":"","legend":"","description":"","filename":"Fig.5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8209042/v1/d40804c7a787e8eec5b2d7fa.jpg"},{"id":97672476,"identity":"9542a8ee-dccf-47a9-a614-7c40204a77cc","added_by":"auto","created_at":"2025-12-08 09:38:05","extension":"xml","order_by":6,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":9195,"visible":true,"origin":"","legend":"","description":"","filename":"aectAECTD2500777.xml","url":"https://assets-eu.researchsquare.com/files/rs-8209042/v1/ccc293d83ecb621bed575aa7.xml"},{"id":97536896,"identity":"9288aa22-0f8a-4558-b6f1-aa62d7c55bce","added_by":"auto","created_at":"2025-12-05 14:30:52","extension":"xml","order_by":7,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":1131,"visible":true,"origin":"","legend":"","description":"","filename":"AECTD250077713076.go.xml","url":"https://assets-eu.researchsquare.com/files/rs-8209042/v1/9a517bbd20e46d40713815f0.xml"},{"id":97671575,"identity":"ba67bc9a-b012-4482-a491-77fbc374d69e","added_by":"auto","created_at":"2025-12-08 09:32:45","extension":"xml","order_by":8,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":902,"visible":true,"origin":"","legend":"","description":"","filename":"AECTD2500777Import.xml","url":"https://assets-eu.researchsquare.com/files/rs-8209042/v1/7edd006fe6bfdd7a1e31a860.xml"},{"id":97671009,"identity":"387997e6-bfdd-46fa-afbc-1e0728b25d4a","added_by":"auto","created_at":"2025-12-08 09:31:44","extension":"xml","order_by":10,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":155183,"visible":true,"origin":"","legend":"","description":"","filename":"AECTD25007770enriched.xml","url":"https://assets-eu.researchsquare.com/files/rs-8209042/v1/039d49ca4fe8453a7d5109cd.xml"},{"id":97671667,"identity":"facc2f9e-cc69-4052-aa7c-9ce6d6f2666c","added_by":"auto","created_at":"2025-12-08 09:32:53","extension":"jpg","order_by":11,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":1215564,"visible":true,"origin":"","legend":"","description":"","filename":"Fig.1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8209042/v1/3d478c9df6d64c45f55189d4.jpg"},{"id":97536917,"identity":"ac5def62-bba2-4005-8dd3-748500e2729a","added_by":"auto","created_at":"2025-12-05 14:30:53","extension":"jpg","order_by":12,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":577828,"visible":true,"origin":"","legend":"","description":"","filename":"Fig.2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8209042/v1/6b479ec94c885330b83054fd.jpg"},{"id":97536902,"identity":"c7c8ea6b-fe4a-4b9a-a414-4a9f971e42aa","added_by":"auto","created_at":"2025-12-05 14:30:52","extension":"jpg","order_by":13,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":674651,"visible":true,"origin":"","legend":"","description":"","filename":"Fig.3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8209042/v1/c2f72b3e064ebeb67985e7f4.jpg"},{"id":97536899,"identity":"b91f7dd4-b8d2-4c45-8031-9d666ff38e34","added_by":"auto","created_at":"2025-12-05 14:30:52","extension":"jpg","order_by":14,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":477879,"visible":true,"origin":"","legend":"","description":"","filename":"Fig.4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8209042/v1/03d6c4c0247c407402737268.jpg"},{"id":97671031,"identity":"37f08ecd-f63b-417b-863c-773f4ee2b181","added_by":"auto","created_at":"2025-12-08 09:31:46","extension":"jpg","order_by":15,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":970436,"visible":true,"origin":"","legend":"","description":"","filename":"Fig.5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8209042/v1/4738b6af0bcc625e4b0b338b.jpg"},{"id":97536915,"identity":"af6e3c39-a2ee-4789-9ab2-69d922abd96b","added_by":"auto","created_at":"2025-12-05 14:30:52","extension":"jpeg","order_by":16,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":295397,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8209042/v1/f3f091969742187e8598d97e.jpeg"},{"id":97536898,"identity":"24fa0a0b-c180-45b7-94ff-8d24ea5ff06e","added_by":"auto","created_at":"2025-12-05 14:30:52","extension":"jpeg","order_by":17,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":188402,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage2.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8209042/v1/6bdcb21271802d33824121f4.jpeg"},{"id":97536906,"identity":"87950de7-408c-4adc-821f-38f506e7d787","added_by":"auto","created_at":"2025-12-05 14:30:52","extension":"jpeg","order_by":18,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":232697,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage3.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8209042/v1/1a18d807fbe0b92567011290.jpeg"},{"id":97672271,"identity":"ff8a71cb-e481-4288-bef2-254d7531c74a","added_by":"auto","created_at":"2025-12-08 09:35:00","extension":"jpeg","order_by":19,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":115535,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage4.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8209042/v1/6e38a7fe227dcf3d9f60dd8c.jpeg"},{"id":97671866,"identity":"ae4a50b9-0f16-4251-897e-d2c598c448bb","added_by":"auto","created_at":"2025-12-08 09:33:12","extension":"jpeg","order_by":20,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":153883,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage5.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8209042/v1/49c6141f9fa7e6682c42a10f.jpeg"},{"id":97671592,"identity":"1fb87edb-848a-4e80-9822-5ddedaa13c2f","added_by":"auto","created_at":"2025-12-08 09:32:46","extension":"png","order_by":21,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":910845,"visible":true,"origin":"","legend":"","description":"","filename":"OnlineFig.1.png","url":"https://assets-eu.researchsquare.com/files/rs-8209042/v1/21a9f8cf743ccd3b553990f9.png"},{"id":97536904,"identity":"0a46a42b-0832-48fd-a28b-706ad7632722","added_by":"auto","created_at":"2025-12-05 14:30:52","extension":"png","order_by":22,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":345961,"visible":true,"origin":"","legend":"","description":"","filename":"OnlineFig.2.png","url":"https://assets-eu.researchsquare.com/files/rs-8209042/v1/083ff5dc30c82fbd85b3e532.png"},{"id":97671629,"identity":"26d0fd03-3403-43b8-81ea-5c09ab40b81c","added_by":"auto","created_at":"2025-12-08 09:32:50","extension":"png","order_by":23,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":466688,"visible":true,"origin":"","legend":"","description":"","filename":"OnlineFig.3.png","url":"https://assets-eu.researchsquare.com/files/rs-8209042/v1/fc2cae243c4d8ddad7b1a063.png"},{"id":97536908,"identity":"950f3cc6-1e7e-4843-9a80-47b6aa10bfe8","added_by":"auto","created_at":"2025-12-05 14:30:52","extension":"png","order_by":24,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":138580,"visible":true,"origin":"","legend":"","description":"","filename":"OnlineFig.4.png","url":"https://assets-eu.researchsquare.com/files/rs-8209042/v1/5e0e7ed125b45f37c9f85c75.png"},{"id":97536907,"identity":"059534ff-5982-4d40-b0dc-792c316af180","added_by":"auto","created_at":"2025-12-05 14:30:52","extension":"png","order_by":25,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":706654,"visible":true,"origin":"","legend":"","description":"","filename":"OnlineFig.5.png","url":"https://assets-eu.researchsquare.com/files/rs-8209042/v1/b0debbedc0c4e7a755d37939.png"},{"id":97672787,"identity":"c51cebe5-3808-4dc2-8508-ef4b31fc919a","added_by":"auto","created_at":"2025-12-08 09:38:49","extension":"png","order_by":26,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":93501,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-8209042/v1/9b8904cdc12b87d8a76217ba.png"},{"id":97671800,"identity":"0d5b84cb-7a1c-4c44-8377-104daa6f2755","added_by":"auto","created_at":"2025-12-08 09:33:07","extension":"png","order_by":27,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":50654,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-8209042/v1/31aa90ca0a6e5b8147d3294b.png"},{"id":97671590,"identity":"cefeb53a-b732-4650-9e89-2e4c0bc7c8ef","added_by":"auto","created_at":"2025-12-08 09:32:46","extension":"png","order_by":28,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":67828,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-8209042/v1/f6174d675199ab946b44fb5e.png"},{"id":97536912,"identity":"bb4865ab-8bff-420e-a57e-97a068a29c32","added_by":"auto","created_at":"2025-12-05 14:30:52","extension":"png","order_by":29,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":22706,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-8209042/v1/1217b298a2d8e76acb77b69f.png"},{"id":97536909,"identity":"079f01d0-3393-40f0-bc8b-6d3aed5c6f99","added_by":"auto","created_at":"2025-12-05 14:30:52","extension":"png","order_by":30,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":52179,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-8209042/v1/50d72abf283d96e6232a6f08.png"},{"id":97671683,"identity":"85923126-002c-4aea-a675-6ae20af69f8d","added_by":"auto","created_at":"2025-12-08 09:32:54","extension":"xml","order_by":31,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":153780,"visible":true,"origin":"","legend":"","description":"","filename":"AECTD25007770structuring.xml","url":"https://assets-eu.researchsquare.com/files/rs-8209042/v1/37af105ba671993903525091.xml"},{"id":97536920,"identity":"1cc18bc4-ef54-4df8-b610-90c3c07fcbcc","added_by":"auto","created_at":"2025-12-05 14:30:53","extension":"html","order_by":32,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":162004,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-8209042/v1/bdd0936deca692b11f8cf8cc.html"},{"id":97536885,"identity":"365aa13d-c6e9-4530-88ea-1175952a90ae","added_by":"auto","created_at":"2025-12-05 14:30:52","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":1215564,"visible":true,"origin":"","legend":"\u003cp\u003eMap of soil and sediment sampling locations. Wind frequency and speed in Norilsk were measured for the period 2005-2025 at a height of 10-12 m (according to rp5.ru)\u003c/p\u003e","description":"","filename":"Fig.1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8209042/v1/d4d253facd0699fa30ebabd1.jpg"},{"id":97536891,"identity":"15d7b9fc-f816-49f2-83c3-d2733baeef52","added_by":"auto","created_at":"2025-12-05 14:30:52","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":577828,"visible":true,"origin":"","legend":"\u003cp\u003eDistribution of low- (2-3 rings) and high-molecular-weight (4-6 rings) PAHs in soils and bottom sediments across different Arctic subregions. *Subregions are defined according to Arctic Biodiversity Trends 2010: Selected indicators of change report by the Conservation of Arctic Flora and Fauna (CAFF). Different letters indicate statistically significant differences (p \u0026lt; 0.05) in the relative PAH content within each subregion, based on pairwise comparisons using the Mann-Whitney test with Bonferroni correction. The following PAHs were considered: 2-ring PAHs: naphthalene, acenaphthene, acenaphthylene, fluorene; 3-ring PAHs: phenanthrene, anthracene, fluoranthene; 4-ring: chrysene, pyrene, benzo(a)anthracene, benzo(b)fluoranthene, benzo(k)fluoranthene; 5-ring: benzo(a)pyrene, dibenz(a, h)anthracene, indeno(1,2,3-c,d)pyrene; 6-ring: benzo (g,h,i) perylene.\u003c/p\u003e","description":"","filename":"Fig.2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8209042/v1/361a830a6262ad542e6e3e41.jpg"},{"id":97672902,"identity":"2632c392-311c-4ec2-a8d4-7d555fe7d115","added_by":"auto","created_at":"2025-12-08 09:39:04","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":674651,"visible":true,"origin":"","legend":"\u003cp\u003eDistribution of PCB homologous groups across Arctic subregions. *Statistically significant differences between subregions were identified for this indicator, using the Kruskal-Wallis test (p\u0026lt;0.05). Different letters indicate statistically significant differences (p\u0026lt;0.05) in the relative abundance of PCB homologous groups within a subregion, based on pairwise comparisons using the Mann-Whitney test with Bonferroni correction. **Subregions are identified according to Arctic Biodiversity Trends 2010: Selected indicators of change report by the Conservation of Arctic Flora and Fauna (CAFF).\u003c/p\u003e","description":"","filename":"Fig.3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8209042/v1/efd4a9da09c26a0e0d0d8215.jpg"},{"id":97673012,"identity":"fd01e758-20fd-4d17-91bb-ab79bb6dccc8","added_by":"auto","created_at":"2025-12-08 09:39:18","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":477879,"visible":true,"origin":"","legend":"\u003cp\u003eNon-metric multidimensional scaling (nMDS) plot (stress = 0.07, Euclidean distance) showing comparisons between soils and bottom sediments samples and some commercial PCB mixtures\u003c/p\u003e","description":"","filename":"Fig.4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8209042/v1/f0758b74e67b2127168191f4.jpg"},{"id":97671841,"identity":"be50dacf-8a01-4610-a2a4-419d45e031be","added_by":"auto","created_at":"2025-12-08 09:33:10","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":970436,"visible":true,"origin":"","legend":"\u003cp\u003eNon-metric multidimensional scaling (nMDS) plot (stress = 0.08, Euclidean distance) with ANOSIM test (R=0.27, p\u0026lt;0.0001) showing variations in PAH composition in soils and sediments of the sampling sites across different Arctic subregions. Point size is proportional to ∑\u003csub\u003e16\u003c/sub\u003ePAH. The envfit function was used to plot geographical (latitude, longitude, distance) and chemical (pH, salinity) parameters of samples affecting PAH composition. Only significant (p\u0026lt;0.05) vectors were plotted. * Distance from the nearest industrial city (Norilsk). ** Sub regions separated according to Arctic Biodiversity Trends 2010: Selected indicators of change report by the Conservation of Arctic Flora and Fauna (CAFF)\u003c/p\u003e","description":"","filename":"Fig.5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8209042/v1/4328812f282f1f8a513cf63a.jpg"},{"id":97896404,"identity":"e315e954-8cc2-47a8-ae5f-06d77e86acd0","added_by":"auto","created_at":"2025-12-10 15:36:29","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":4524548,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8209042/v1/121a2467-4c9d-45c7-9339-29e9c87f6386.pdf"},{"id":97536897,"identity":"e3f71ff1-4a9a-498c-a906-092185ec5e36","added_by":"auto","created_at":"2025-12-05 14:30:52","extension":"xlsx","order_by":9,"title":"","display":"","copyAsset":false,"role":"supplement","size":15044,"visible":true,"origin":"","legend":"","description":"","filename":"Supplementary.xlsx","url":"https://assets-eu.researchsquare.com/files/rs-8209042/v1/190ca68b69df50d08a7c0fb1.xlsx"}],"financialInterests":"","formattedTitle":"\u003cp\u003eContent and Potential Sources of Pahs and Pcbs in Soils and Bottom Sediments of the Siberian Arctic\u003c/p\u003e","fulltext":[{"header":"1. INTRODUCTION","content":"\u003cp\u003eEnvironmental pollution by persistent organic pollutants (POPs) is a global problem. Polyaromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) occupy a special place among the most toxic and carcinogenic POPs.\u003c/p\u003e\u003cp\u003eDue to their high stability, the possibility of long-range atmospheric transport, the ability to bioaccumulate in environmental compartments and food chains even at low concentrations and high toxicity for living organisms, PAHs and PCBs are included in the Protocol on Persistent Organic Pollutants to the Convention on Long-Range Transboundary Air Pollution; PCBs are also included in the Stockholm Convention on Persistent Organic Pollutants (Klyuev \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2000\u003c/span\u003e; Danilina, Kutsenko \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2000\u003c/span\u003e; UNECE 1998; UNEP \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2001\u003c/span\u003e).\u003c/p\u003e\u003cp\u003ePAHs are formed during the incomplete combustion of biomass and fossil fuels, volcanic eruptions, and diagenesis, and are also found in crude oil and its refined products (Balmer et al. \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Khaustov and Redina \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2016\u003c/span\u003e). Thus, PAHs can enter the Arctic environment from both natural and anthropogenic sources with the latter being the most important source of PAH emissions into the environment (Balmer et al. \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Robertson et al. 1998; Wilcke \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2000\u003c/span\u003e). PAH concentrations in soils generally increase with increasing exposure to industrial, transport, and residential heating (Wilcke \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2000\u003c/span\u003e). Of the several hundred existing PAHs 16 were selected by the U.S. Environmental Protection Agency (USEPA) in the mid-1970s as priorities for monitoring: naphthalene, acenaphthene, acenaphthylene, fluorene, phenanthrene, anthracene, fluoranthene, chrysene, pyrene, benzo(a)anthracene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene, dibenz(a,h)anthracene, indeno(1 2, 3-c, d)pyrene, benzo(g, h, i)perylene (Keith \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). According to calculations of the global emissions of 16 priority PAHs for the period from 1960 to 2008, it peaked at 592,000 tons in 1995 and gradually decreased to 499,000 tons in 2008 (Shen et al. \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e2013\u003c/span\u003e).\u003c/p\u003e\u003cp\u003ePCBs have been produced since 1929, and their global atmospheric emissions peaked at 3,000 tons per year in the 1970s (Breivik et al. \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2007\u003c/span\u003e; Gałuszka et al. \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). Their wide industrial use is attributed to their thermal and chemical stability, flame retardancy, and dielectric properties (Erickson, Kaley \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2011\u003c/span\u003e). Following restrictions on PCB production and use, atmospheric emissions decreased to several hundred tons per year by the 2010s (Breivik et al. \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2007\u003c/span\u003e; Carlsson et al. \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). Currently, the main sources of PCB pollution are PCB-containing products and waste electrical and electronic equipment recycling plants (Gioia et al. \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2011\u003c/span\u003e; Breivik et al. \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Gałuszka et al. \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). PCBs can enter the atmosphere through waste incineration, combustion of coal and contaminated biomass, volatilization from polluted water and soil, and certain technological processes, such as paper and pigment production (Eckhardt et al. \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2007\u003c/span\u003e; Gioia et al. \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2011\u003c/span\u003e; Wolska et al. \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e2014\u003c/span\u003e; Khairy et al. \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2015\u003c/span\u003e; Breivik et al. \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Vorkamp, ​​2016; Gałuszka et al. \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). PCB emissions from natural processes are considered to be insignificant compared to anthropogenic sources (Gałuszka et al. \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2020\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eArctic contamination with PAHs and PCBs occurs primarily through long-range atmospheric transport (Balmer et al. \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Carlsson et al. \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). At high latitudes and low temperatures, deposition prevails over evaporation, resulting in the deposition of atmospheric PAHs and PCBs in Arctic environmental objects (Wania and Mackay \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e1996\u003c/span\u003e; Sharpe \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2008\u003c/span\u003e; Balmer et al. \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Gałuszka et al. \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). More volatile low-molecular PAHs (2\u0026ndash;3 rings) and low-chlorinated PCBs (tri- and pentachlorinated biphenyls) are capable of migrating to high latitudes (Wilcke \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2000\u003c/span\u003e; Agrell et al. \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e1999\u003c/span\u003e; Gałuszka et al. \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). Although, global PAH emissions are expected to decline, this process may be less evident in the Arctic, as the contribution of local sources may increase in the future as oil production and shipping develop. Future climate change may promote the re-evaporation of PAHs from the environment, which will become a source of secondary emissions into the Arctic atmosphere (Balmer et al. \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). The ban on the production and use of the most hazardous PCBs contributed to a significant decrease in their concentrations in Arctic natural objects up to the 2000s. However, the rate of decline later slowed, likely due to the slow degradation of these substances in Arctic conditions, input from secondary sources, and ongoing anthropogenic emissions (AMAP 2020; Carlsson et al. \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2018\u003c/span\u003e; Gorbacheva and Novikov \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). There is no consensus in the scientific literature on future trends in PCB levels under global climate change, but rising air temperatures will most likely lead to PCB degradation and decrease in their concentrations in the environment (Gałuszka et al. \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2020\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eFor decades, the north of Western Siberia has been subject to intensive development of oil and gas condensate fields, associated with changes across all environmental compartments (Kukushkin \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Opekunova et al. \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Moskovchenko, Romanenko \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). The vast majority of pollutant emissions in the region are associated with fossil fuel extraction, petroleum production, and the transportation of oil, gas, and their refined products through pipelines (Opekunova et al. \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). Active oil and gas development can lead to PAH and PCB contamination of bottom sediments and soils (Opekunov et al. \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). At the same time, the Arctic is home to indigenous peoples of the North, whose livelihoods depend on nomadic reindeer herding. Lichens, an important food resource for reindeer, have the ability to accumulate pollutants, including POPs (Blasco et al. \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2006\u003c/span\u003e; Holma-Suutari et al. \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2014\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eThus, the analysis and monitoring of background levels of PAHs and PCBs in the Arctic are becoming increasingly important due to the need of pollution assessment in the context of active industrial development and global climate change. The study focused on soils and bottom sediments of rivers and lakes in the Arctic zone of Western and Central Siberia, unaffected by oil and gas production, as well as lake bottom sediments located directly within the oil and gas production area. This paper presents the first study of PAH and PCB contents in soil and bottom sediment samples along a latitudinal transect across the Siberian sector of the Arctic.\u003c/p\u003e\u003cp\u003eThe aim of this study is to assess the content of POPs: 16 priority PAHs and 6 homologous groups of PCBs in soils and bottom sediments of the Siberian Arctic. The objectives of the study were: 1) to assess the total content and relative distribution of PAH and PCB in soils and bottom sediments along a latitudinal gradient in areas not affected by oil and gas production; 2) to identify the sources of PAH and PCB pollution of soils and bottom sediments outside oil and gas production areas; 3) to assess the impact of oil and gas production on PAH and PCB pollution.\u003c/p\u003e\u003cp\u003eIt is assumed that: 1) the content of PAHs and PCBs in soils and bottom sediments in the north of Western and Central Siberia outside oil and gas production areas increases with latitude. This trend may be driven by less favorable conditions for the decomposition and volatilization of pollutants, as well as by atmospheric transfers from the mining enterprises of the Norilsk industrial complex; 2) since oil and gas production can be an important factor contributing to POPs pollution, the level of pollution and composition of pollutants in the area of ​​active fields differ from those in areas not affected by oil and gas production.\u003c/p\u003e"},{"header":"2. MATERIALS AND METHODS","content":"\u003cp\u003eThe soils and bottom sediments of rivers and lakes in the Ob and Yenisei interfluve were selected for background pollution assessment. Sampling sites were located along a transect crossing the Arctic subregions identified by the Conservation of Arctic Flora and Fauna (CAFF) working group taking into account the bioclimatic features of the territory (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). In this study, soils and bottom sediments were analyzed within the framework of subregions to reduce variability and increase the statistical power of state and trend assessments. The study area has a temperate and mid-continental climate. According to the physical and geographical zoning, the study area extends from forest (forest-swamp) and forest-tundra regions (Western Siberia) in the south to typical and mountain tundra with glacial-nival complexes (Central Siberia) in the north. The soils are represented by complexes of tundra gley soils, bog tundra soils, soils of spots and cracks in the north, and gley-podzolic soils in the south (National Atlas\u0026hellip; 2007). Sampling was conducted in 2005, prior to the commencement of hydrocarbon production in the study area. At the time of sampling, the area was only slightly affected by human activities and was therefore considered as a background site for this study. To assess PAH and PCB contamination from oil and gas production, bottom sediments from seven lakes near the Tazovsky and Zapolyarnoye oil and gas condensate fields were sampled in 2025. The samples were frozen immediately and kept for less than 30 days before analysis.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eConcentrations of 16 priority PAHs were determined in 92 soil and sediment samples: naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benzo(a)anthracene, chrysene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene, dibenz(a,h) anthracene, indeno(l,2,3-cd) pyrene, and benzo (g,h,i)perylene. \u0026sum;16PAHs is the sum of these 16 concentrations. The PCB contents in 86 soil and sediment samples were estimated within homologous groups (di-, tri-, tetra-, penta-, hexa-, and heptachlorinated biphenyls). \u0026sum;PCB is defined as the sum of the concentrations of all considered homologous groups of PCBs.\u003c/p\u003e\u003cp\u003eAnalytical studies were conducted by the scientific center Taifun (Obninsk). PAH analysis was performed by extracting the compounds with dichloromethane, followed by sequential purification of the extracts using activated copper to remove organic sulfur compounds, purification of impurities interfering with the analysis on silica gel columns, and subsequent chromatograph mass spectrometric identification and quantification of individual PAHs. PCB determination involved extraction of the analyzed compounds with dichloromethane in a Soxhlet apparatus. Activated copper and florisil column chromatography were used to purify the extracts. Compound identification was performed using chromatograph mass spectrometry. A system of isotopically labeled surrogate and internal standards, added to the samples at various stages of analysis, was used to control the quality of the analysis.\u003c/p\u003e\u003cp\u003eR version 4.3.2 (ggplot2 (3.5.1), vegan (2.6-8), ggalt (0.4.0), ggsci (3.2.0) packages) and MS Excel 2019 were used for statistical processing and data visualization. The Kolmogorov-Smirnov test at a significance level of α\u0026thinsp;=\u0026thinsp;0.05 supported the hypothesis that the distribution follows the normal law. Since the distributions of most of the variables under consideration did not confirm the hypothesis of normal distribution, the results are presented as medians. Differences between groups were evaluated using the nonparametric Mann-Whitney test at α\u0026thinsp;=\u0026thinsp;0.05 with Bonferroni correction. Correlations between parameters were estimated using Spearman\u0026rsquo;s rank correlation coefficient. Ordination methods were performed using nonmetric multidimensional scaling (nMDS). The ANOSIM test was used to analyze similarities in the multivariate structures of the samples.\u003c/p\u003e"},{"header":"3. RESULTS","content":"\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e\u003ch2\u003e3.1. Total PAH content\u003c/h2\u003e\u003cp\u003eTable \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e shows the results of the analysis of 16 priority PAHs. One-quarter of the analyzed samples did not contain any of the analyzed PAHs at concentrations above the method\u0026rsquo;s detection limit. Only samples with PAHs concentrations above the detection limit were included in the calculations.\u003c/p\u003e\u003cp\u003eThe total concentration of 16 priority PAHs (\u0026sum;\u003csub\u003e16\u003c/sub\u003ePAH) varies from 0.3 to 53 \u0026micro;g/kg dry weight in soils and from 0.4 to 113 \u0026micro;g/kg in river and lake sediments. The wide ranges of total PAH concentrations likely reflect both the diversity of natural conditions and anthropogenic impact. The medians of \u0026sum;\u003csub\u003e16\u003c/sub\u003ePAH for the studied soils and bottom sediments were similar and amounted to 15 \u0026micro;g/kg and 17 \u0026micro;g/kg respectively. No statistically significant differences in the total PAH content between the studied soils and bottom sediments were found at a significance level of 0.05.\u003c/p\u003e\u003cp\u003eWhen examining the pollution levels by waterbody type, it was found that the \u0026sum;\u003csub\u003e16\u003c/sub\u003ePAHs in lake bottom sediments ranged from 2.7 to 90.8 \u0026micro;g/kg, and those of rivers \u0026ndash; from 0.4 to 112.6 \u0026micro;g/kg. The median \u0026sum;\u003csub\u003e16\u003c/sub\u003ePAHs in lake bottom sediments was 19.3 \u0026micro;g/kg, and 13 \u0026micro;g/kg in river bottom sediments. In terms of the total PAHs, the bottom sediments of the studied rivers and lakes also did not differ statistically significantly at the 0.05 significance level.\u003c/p\u003e\u003cp\u003eIn the Arctic subregions identified according to CAFF, the statistical significance of the difference in \u0026sum;\u003csub\u003e16\u003c/sub\u003ePAHs in soils (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05) was revealed the regional patterns of PAH accumulation were taken into account. The median \u0026sum;\u003csub\u003e16\u003c/sub\u003ePAHs in soils increased from 9.7 \u0026micro;g/kg in the subarctic to 15 and 13.7 \u0026micro;g/kg in the low and high Arctic, respectively. In contrast, total PAHs concentrations in bottom sediments did not show statistically significant differences among the Arctic subregions at a significance level of 0.05. Nevertheless, the median \u0026sum;\u003csub\u003e16\u003c/sub\u003ePAHs in bottom sediments increased from 14 \u0026micro;g/kg in the subarctic to 18.5 \u0026micro;g/kg in the low Arctic.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e\u003ch2\u003e3.2. Relative distribution of PAHs\u003c/h2\u003e\u003cp\u003eThe distribution of PAHs in soils and bottom sediments in terms of the number of rings in molecules in different Arctic subregions is shown (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Low molecular weight PAHs (2\u0026ndash;3 rings), including naphthalene, acenaphthene, acenaphthylene, fluorene, phenanthrene, anthracene, and fluoranthene, dominate in all the subregions under consideration. Their proportions are 92.7%, 97.8%, and 100% in the subarctic, low Arctic, and high Arctic, respectively. The proportion of two-ring PAHs increases from 80.6% in the subarctic to 90.3% in the high Arctic. Among all the PAHs studied, naphthalene is the predominant compound in the vast majority of samples.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eThe median relative content of high-molecular PAHs (4\u0026ndash;6 rings), including chrysene, pyrene, benzo(a)anthracene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene, dibenz(a,h)anthracene, indeno(1,2,3-c,d)pyrene, benzo(g,h,i)perylene, is 7.3% in the subarctic and does not exceed 3.5% in the low and high Arctic. The smallest percentage is occupied by PAHs with 5\u0026ndash;6 rings in their structure.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e\u003ch2\u003e3.3. Total PCB content\u003c/h2\u003e\u003cp\u003eTable S2 presents the results of the analysis of PCB homologous groups (di-, tri-, tetra-, penta-, hexa-, and heptachlorinated biphenyls). Despite the ban on PCB production, only one-quarter of the analyzed samples contained no PCBs of any of the homologous groups at concentrations above the detection limit of the analytical method. Only those samples with PCB concentrations exceeding the detection limit were considered in the processing.\u003c/p\u003e\u003cp\u003eTotal PCBs (\u0026sum;PCBs) varied from 0.2 to 9 \u0026micro;g/kg dry weight in soils and from 0.3 to 3.4 \u0026micro;g/kg in river and lake bottom sediments. The median \u0026sum;PCBs of the studied soils and bottom sediments were similar and amounted to 1.1 \u0026micro;g/kg and 1 \u0026micro;g/kg, respectively. No statistically significant differences in \u0026sum;PCBs were found between the studied soils and bottom sediments at a significance level of 0.05.\u003c/p\u003e\u003cp\u003eIt was discovered that the amount of \u0026sum;PCBs in lake bottom sediments varies from 0.8 to 3.4 \u0026micro;g/kg, and in rivers \u0026ndash; from 0.3 to 2.3 \u0026micro;g/kg depending on the kind of water body. The median \u0026sum;PCBs in lake bottom sediments was 1.6 \u0026micro;g/kg, compared with 0.7 \u0026micro;g/kg in river bottom sediments. \u0026sum;PCBs in the bottom sediments of the studied lakes were higher than in the bottom sediments of the rivers (p\u0026thinsp;\u0026lt;\u0026thinsp;0.01).\u003c/p\u003e\u003cp\u003e\u0026sum;PCBs in soils and bottom sediments do not differ statistically and across the Arctic subregions identified by CAFF at the 0.05 significance level, according to an analysis of regional contamination patterns. Median \u0026sum;PCBs in soils were 0.9 1.3, and 0.8 \u0026micro;g/kg in the subarctic, low and high Arctic, respectively. Median \u0026sum;PCBs in bottom sediments were 0.9 and 1.0 \u0026micro;g/kg in the subarctic and low Arctic, respectively.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e\u003ch2\u003e3.4. Relative distribution of PCBs\u003c/h2\u003e\u003cp\u003eThe distribution of homologous groups of PCBs in the Arctic subregions is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. The most common are low-chlorinated di-, tri-, tetra-, and penta-CBs. The distribution of the total content of homologous groups of PCBs in various Arctic subregions showed the widespread dominance of penta- and tetrachlorobiphenyls, accounting for 69 to 79%. When analyzing the distribution of homologous groups, no evidence of PCB fractioning was observed among the subregions. This distribution may reflect the composition of various types of Sovol, a mixture of tetra- and pentachlorobiphenyls formerly produced in the USSR and widely used in electrical equipment (Yanin \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e1997\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\u003ch2\u003e3.5. PAH and PCB pollution under the influence of oil and gas production\u003c/h2\u003e\u003cp\u003ePAH pollution associated with oil and gas production, the main anthropogenic impact in northern Western Siberia, was analyzed using lake bottom sediments located near active hydrocarbon fields on the Taz Peninsula. In these sediments, \u0026sum;\u003csub\u003e16\u003c/sub\u003ePAHs ranged from 90 to 838 \u0026micro;g/kg dry weight. The median \u0026sum;\u003csub\u003e16\u003c/sub\u003ePAHs for bottom sediments was 141 \u0026micro;g/kg dry weight (Table \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eThe median relative content of low-molecular PAHs (2\u0026ndash;3 rings) in the bottom sediments of the sampled lakes was 92%, high-molecular PAHs (4\u0026ndash;6 rings) accounted for 8%. Two-ring PAHs were the most represented group, comprising 68.2% of the PAH structure. The main PAH in four of the seven studied lakes is naphthalene, followed by pyrene, phenanthrene, fluorene.\u003c/p\u003e\u003cp\u003eThe median \u0026sum;PCB concentration in lake sediments located near active hydrocarbon fields was 1.1 \u0026micro;g/kg dry weight (Table S2). The distribution of the total content of homologous PCB groups showed the dominance of pentachlorobiphenyls, accounting for 50 to 64%.\u003c/p\u003e\u003c/div\u003e"},{"header":"4. DISCUSSION","content":"\u003cdiv id=\"Sec10\" class=\"Section2\"\u003e\u003ch2\u003e4.1. Total content and relative distribution of PAHs\u003c/h2\u003e\u003cp\u003eThe concentration of benzo(a)pyrene in the sampled soils does not exceed the established permissible exposure limit of 20 \u0026micro;g/kg (Sanitary Regulations and Standards 1.2.3685-21). For other PAHs, maximum permissible concentrations and approximate permissible limits have not been established in the Russian Federation. The concentrations of individual compounds (benzo(a)anthracene, benzo(b)fluoranthene, benzo(k)fluoranthene, dibenz(a,h)anthracene, indeno(1,2,3-cd)pyrene, phenanthrene, pyrene) in the studied soils are several times lower than the Canadian standards for agricultural soils, which specify an upper limit of 100 \u0026micro;g/kg for individual PAH compounds (Canadian Soil Quality Guidelines\u0026hellip; 2007). According to the classification proposed by Maliszewska-Kordybach (\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e1996\u003c/span\u003e), the studied soils are classified as \u0026ldquo;unpolluted\u0026rdquo; based on the total PAH content (\u0026sum;\u003csub\u003e16\u003c/sub\u003ePAH \u0026lt;\u0026thinsp;200 \u0026micro;g/kg).\u003c/p\u003e\u003cp\u003eThe sums of concentrations of 14 individual PAHs in the studied soils (\u0026sum;\u003csub\u003e14\u003c/sub\u003ePAH = 0.3\u0026ndash;53 \u0026micro;g/kg) are comparable to those in polar soils of the Russian Arctic not affected by anthropogenic influence (\u0026sum;\u003csub\u003e14\u003c/sub\u003ePAH = 5.2-147.1 \u0026micro;g/kg; Abakumov et al. \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). When considering the sum of 16 PAHs, the studied soils (from 0.3 to 53 \u0026micro;g/kg) are similar to the background PAH contents in the illuvial horizons of soils in the north of Western Siberia (from 10 to 70 \u0026micro;g/kg; Opekunova et al. \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2022\u003c/span\u003e) and are close to the average level of contamination of Urengoy tundra soils (55 \u0026micro;g/kg; Opekunov et al. \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2012\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eThe concentrations of 16 PAHs in the bottom sediments of rivers and lakes in the studied area (\u0026sum;16PAHs no more than 112.6 \u0026micro;g/kg) are comparable to those in the pelitic sediments of the shelf of the Kara Sea, the Gulf of Ob and the Yenisei Gulf (\u0026sum;\u003csub\u003e14\u003c/sub\u003ePAHs no more than 121.4 \u0026micro;g/g; Dahle et al. \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2003\u003c/span\u003e). The total content of 12 PAHs in the bottom sediments of the studied rivers (\u0026sum;\u003csub\u003e12\u003c/sub\u003ePAHs \u0026le; 112.6 \u0026micro;g/kg) is dozen times lower than in the bottom sediments of rivers in the Yamalo-Nenets Autonomous Okrug (\u0026sum;\u003csub\u003e12\u003c/sub\u003ePAHs = 1,973.9\u0026ndash;18,504 \u0026micro;g/kg), which are subjected to intense anthropogenic impact of oil and gas production (Volkova et al. \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e2023\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eThe Spearman correlation coefficient between \u0026sum;\u003csub\u003e16\u003c/sub\u003ePAHs and the sampling-site latitude was 0.6 at p\u0026thinsp;\u0026lt;\u0026thinsp;0.01. Temperature largely determines the concentration of easily decomposable and most abundant naphthalene in the studied samples (Wilcke, Amelung \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2000\u003c/span\u003e). The Spearman correlation coefficient between \u0026sum;\u003csub\u003e16\u003c/sub\u003ePAHs and the distance from the sampling site to the nearest industrial center (Norilsk) was \u0026minus;\u0026thinsp;0.5 at p\u0026thinsp;\u0026lt;\u0026thinsp;0.01. It is also worth noting the predominance of south-easter winds in the Norilsk area (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e), which confirms the influence of the Norilsk industrial complex on the formation of pollution in the study area. Thus, an increase in the content of 16 PAHs with latitude may be due to the presence of a large industrial center and a harsh climate, which creates less favorable conditions for the decomposition and volatilization of PAHs. Natural organochlorines decomposition is decelerated in cold climate providing prolonged occurrence of these compounds unchanged (AMAP 2020).\u003c/p\u003e\u003cp\u003eLow-molecular-weight PAHs are most abundant in the study area. A decline in the proportion of volatile and readily degradable PAHs with increasing mean annual air temperature was previously noted by Wilcke and Amelung (\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2000\u003c/span\u003e). Naphthalene, which predominates in the vast majority of samples, originates from both natural and anthropogenic processes. A global analysis of PAH distribution in 27 regions revealed a predominance of naphthalene, phenanthrene, and perylene over high-molecular-weight PAHs in background soils with low total PAH concentrations (Wilcke \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e2007\u003c/span\u003e). The predominance of light PAHs has also been reported in background Arctic soils (Abakumov et al. \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). The tendency toward an increase in the proportion of two-ring PAH compounds in soils and bottom sediments of the high-latitude Arctic is observed due to the previously described phenomenon of fractionation as a result of long-range atmospheric transport of more volatile low-molecular compounds, in particular naphthalene (Wania and Mackay \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e1996\u003c/span\u003e; Wilcke and Amelung \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2000\u003c/span\u003e). Among the high-molecular PAHs in the studied samples, chrysene and benzo(b)fluoranthene were most often predominant, both can originate from anthropogenic as well as natural sources (Khaustov and Redina \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2016\u003c/span\u003e).\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\u003ch2\u003e4.2. Total content and relative distribution of PCBs\u003c/h2\u003e\u003cp\u003ePCB levels in the sampled soils do not exceed the permissible exposure limit of 20 \u0026micro;g/kg established in the Russian Federation (Sanitary Regulations and Standards 1.2.3685-21). The maximum PCB concentrations in the sampled soils and bottom sediments are dozen times lower than the Canadian standard for agricultural soils, set at 500 \u0026micro;g/kg (Canadian Soil Quality Guidelines\u0026hellip; 2007).\u003c/p\u003e\u003cp\u003eThe sum of dichlorinated biphenyl concentrations in the studied soils (0.03\u0026ndash;0.37 \u0026micro;g/kg) are consistent with those reported for soils of the oil and gas production areas of the Yamalo-Nenets Autonomous Okrug (\u0026sum;\u003csub\u003e3\u003c/sub\u003ePCB = 0.09\u0026ndash;0.74 \u0026micro;g/kg; Opekunov et al. \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). The PCB content in the bottom sediments of the sampled lakes (\u0026sum;PCB\u0026thinsp;=\u0026thinsp;0.8\u0026ndash;3.4 \u0026micro;g/kg) is comparable to the sum of 10 PCB congeners in the bottom sediments of lakes in the Arctic zone of Russia (\u0026sum;\u003csub\u003e10\u003c/sub\u003ePCB = 0.38\u0026ndash;7.9 \u0026micro;g/kg; Skotvold, Savinov \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2003\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eIn contrast to \u0026sum;\u003csub\u003e16\u003c/sub\u003ePAHs no significant correlations were found between \u0026sum;PCBs and the geographic parameters examined (latitude and longitude of sampling, distance to the nearest industrial center \u0026ndash; Norilsk).\u003c/p\u003e\u003cp\u003eSignificant increase of tetra-, pentachlorobiphenyls contents to the north of 60\u0026deg; N was registered before in Siberia (Mamontova et al. \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2016\u003c/span\u003e). A comparison of the percentage distribution of homologous PCB homologous groups in the studied soils and bottom sediments with those in the Sovol (USSR, GSO 7821\u0026thinsp;\u0026minus;\u0026thinsp;2000) and Aroсlor (USA, Toxicological Profile for Polychlorinated Biphenyls (PCBs) commercial mixtures showed that the studied samples were mostly contaminated with Sovol (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). The calculated Spearman correlation coefficients also showed a high similarity between the composition of the contaminants and the composition of Sovol (r\u003csub\u003es\u003c/sub\u003e = 0.705-1.000, p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Only 5 of 86 samples showed no statistically significant correlation with any of the commercial PCB mixtures analyzed.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\u003ch2\u003e4.3. Sources of PAHs and PCBs\u003c/h2\u003e\u003cp\u003ePossible sources of background PAH pollution were assessed by ordinating the sampled stations based on their PAH composition using non-metric multidimensional scaling (nMDS, Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e). For analytes with concentrations below the detection limit of the method, half of their detection limits were adopted. The ANOSIM test showed differences (R\u0026thinsp;=\u0026thinsp;0.27, p\u0026thinsp;\u0026lt;\u0026thinsp;0.0001) in the PAH composition among different subregions. The pattern allows us to assume the influence of mixed emissions from various pollution sources, combusted materials and combustion conditions in the subarctic due to the large scattering of the studied stations along the PAH distribution profile. Atmospheric transport can also contribute to systematic differences in PAH distribution profiles (Wilcke \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e2007\u003c/span\u003e). The higher similarity in PAH composition among sampled sites in northern regions may result from both a smaller number of sources, materials, and combustion conditions, and PAH fractionation due to atmospheric transport of volatile compounds on a local scale.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eInclusion of geographic (latitude and longitude of sampling, distance to the nearest industrial center \u0026ndash; Norilsk) and chemical (pH, salinity as a sum of SO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e, Cl\u003csup\u003e\u0026minus;\u003c/sup\u003e, NO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003e, Ca\u003csup\u003e2+\u003c/sup\u003e, Na\u003csup\u003e+\u003c/sup\u003e, K\u003csup\u003e+\u003c/sup\u003e, Mg\u003csup\u003e2+\u003c/sup\u003e ions in soil/bottom sediments) parameters in the ordination showed that differences in the PAH composition of the studied soils and bottom sediments are affected by the sampling latitude (r\u003csub\u003e2\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;0.55, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001) and the distance to the nearest large industrial center (r\u003csub\u003e2\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;0.45, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), which reflects the influence of atmospheric transport of PAHs. To determine the origin of PAH pollution, commonly used isomeric ratios of fluoranthene to pyrene (Flt/Py) and phenanthrene to anthracene (Phe/An) concentrations were also considered. Most of the studied samples were characterized by Flt/Py\u0026thinsp;\u0026gt;\u0026thinsp;1 and Phe/An \u0026lt;\u0026thinsp;10 values, indicating the dominant influence of pyrogenic anthropogenic sources of PAHs (Soclo et al. 2000).\u003c/p\u003e\u003cp\u003eNo significant correlations were found between \u0026sum;\u003csub\u003e16\u003c/sub\u003ePAHs and \u0026sum;PCBs in soils and bottom sediments, which may indicate different sources of their input (Wolska et al. \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). According to the ANOSIM test, the composition of PCBs in soils and bottom sediments does not differ significantly among Arctic subregions. Unlike PAHs, climate and distance from major industrial centers have a less pronounced effect on PCB distribution. The nature of PCB contamination of the studied soils and bottom sediments may reflect general background contamination resulting from the widespread use of Sovol in the former USSR.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e\u003ch2\u003e4.4. PAH and PCB pollution under the influence of oil and gas production\u003c/h2\u003e\u003cp\u003eTotal PAH concentrations in bottom sediments near active hydrocarbon fields differ statistically significantly from bottom sediments located in lakes in background areas (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). The median \u0026sum;\u003csub\u003e16\u003c/sub\u003ePAH in bottom lake sediments from the oil and gas production area (141 \u0026micro;g/kg dry weight) is 7 times higher than the value in bottom lake sediments in the studied background areas (19 \u0026micro;g/kg dry weight).\u003c/p\u003e\u003cp\u003eA number of features were noted in the PAH structure. Low-molecular-weight PAHs (2\u0026ndash;3 rings), similar to background areas, were the most abundant in the sampled lakes. The median relative content of high-molecular-weight PAHs in the bottom sediments of the studied lakes (8%) was higher than in the bottom sediments of the sampled background subarctic lakes (less than 3.5%). This indicates that anthropogenic impact from oil and gas production increases the proportion of of heavy PAHs along with the total content. It has previously been shown that the PAH content in river bottom sediments increases under the influence of intensive hydrocarbon production (Volkova et al. \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). In addition, an increase in the proportion of heavy PAHs, which are typically technogenic, can serve as a marker of anthropogenic impact (Abakumov et al. \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2015\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eThe median \u0026sum;PCB for bottom sediments of lakes near hydrocarbon fields (1.1 \u0026micro;g/kg dry weight) is comparable to \u0026sum;PCB in bottom sediments of the sampled background subarctic lakes (0.91 \u0026micro;g/kg dry weight). In terms of the relative distribution of homologous groups the composition of contaminants, when compared to the background sites, is similar to the composition of the widely used Sovol: the calculation of Spearman's correlation coefficients showed a strong correlation (r\u003csub\u003es\u003c/sub\u003e = 0.803-1.000, p\u0026thinsp;\u0026lt;\u0026thinsp;0.01) with its composition (USSR, GSO 7821\u0026thinsp;\u0026minus;\u0026thinsp;2000). Thus, hydrocarbon production did not significantly affect the level and composition of PCB contaminants.\u003c/p\u003e\u003c/div\u003e"},{"header":"5. CONCLUSION","content":"\u003cp\u003eArctic soils and bottom sediments were analyzed along a latitudinal gradient for PAH and PCB content, ranging from 0.3 to 112.6 \u0026micro;g/kg and 0.2 to 9 \u0026micro;g/kg dry weight, respectively. The data obtained made it possible to characterize the formation of background PAH and PCB pollution in the study area and can be used for further monitoring studies.\u003c/p\u003e\u003cp\u003eThe hypothesis that PAH and PCB concentrations increase with latitude in the north of Western and Central Siberia outside of oil and gas production areas was partially confirmed for PAHs. The prevailing conditions for contaminant accumulation and degradation, along with proximity to a major industrial center, contributed to the increased total concentrations of 16 priority PAHs. It was shown that the studied soils and bottom sediments are largely contaminated with low-molecular-weight PAHs, while the contaminant composition varies depending on latitude and distance to the nearest industrial center, reflecting the influence of climate and atmospheric transport. The hypothesis was not confirmed for PCBs, whose total amount and composition in background soils and bottom sediments of the subregions studied do not differ significantly, indicating that climate and distance to a major industrial center have a less pronounced effect on PCB pollution. The most common pollutants were low-chlorinated di-, tri-, tetra-, and penta-CBs. Sorting samples by on PCB composition revealed that the studied background samples were predominantly contaminated with Sovol.\u003c/p\u003e\u003cp\u003eThe second hypothesis regarding POP contamination related to oil and gas production was partially confirmed for PAHs. It was shown that in lake bottom sediments in oil and gas production areas, an increase in total PAH content was accompanied by a higher proportion of heavy PAHs compared to background samples. At the same time, oil and gas production activities did not significantly affect either the total PCB content or their composition.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe study was supported by the Russian Science Foundation Project No. 24-16-00163 (data analysis and statistical processing, paper writing).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting Interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e☐\u0026nbsp;The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.\u003cbr\u003e\u0026nbsp;\u0026nbsp;\u003cbr\u003e\u0026nbsp;☒\u0026nbsp;The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:\u003cbr\u003e\u0026nbsp;\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"100%\" class=\"fr-table-selection-hover\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 100px;\"\u003e\n \u003cp\u003eAndrei V. Soromotin reports financial support was provided by the Russian Science Foundation (project No. 24-16-00163)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eConceptualization: Soromotin Andrey Vladimirovich\u003c/p\u003e\n\u003cp\u003eMethodology: Kulikova Maria Andreevna, Samsonov Dmitry Petrovich\u003c/p\u003e\n\u003cp\u003eFormal analysis and investigation: Soromotin Andrey Vladimirovich, Kulikova Maria Andreevna\u003c/p\u003e\n\u003cp\u003eWriting \u0026ndash; original draft preparation: Kulikova Maria Andreevna\u003c/p\u003e\n\u003cp\u003eWriting \u0026ndash; review and editing: Soromotin Andrey Vladimirovich\u003c/p\u003e\n\u003cp\u003eFunding acquisition: Soromotin Andrey Vladimirovich\u003c/p\u003e\n\u003cp\u003eResources: Soromotin Andrey Vladimirovich\u003c/p\u003e\n\u003cp\u003eSupervision: Soromotin Andrey Vladimirovich\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets generated and analyzed during\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003ethe current study are available in the Mendeley Data repository, https://data.mendeley.com/datasets/zjk9vmnzv8/1\u003cstrong\u003e\u003cbr\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eAbakumov EV, Tomashunas VM, Lodygin ED, Gabov DN, Sokolov VT, Krylenkov VA, Kirtsideli IY (2015) Policiklicheskie aromaticheskie uglevodorody v pochvah ostrovov i poberezhij Rossijskogo sektora Arktiki [Polycyclic aromatic hydrocarbons in soils of islands and coasts of Russian sector of Arctic]. Eurasian Soil Science 1433-1438. https://doi.org/10.7868/S0032180X15120023\u003c/li\u003e\n \u003cli\u003eAgrell C, Okla L, Larsson P, Backe C, Wania F (1999) Evidence of latitudinal fractionation of polychlorinated biphenyl congeners along the Baltic Sea region. Environmental science \u0026amp; technology 33(8):1149-1156.\u003c/li\u003e\n \u003cli\u003eAMAP Assessment 2020: POPs and Chemicals of Emerging Arctic Concern: Influence of Climate Change 2021. Arctic Monitoring and Assessment Programme (AMAP), Oslo, Norway\u003c/li\u003e\n \u003cli\u003eBalmer JE, Hung H, Yu Y, Letcher RJ, Muir DC (2019) Sources and environmental fate of pyrogenic polycyclic aromatic hydrocarbons (PAHs) in the Arctic. Emerging Contaminants 5:128-142. https://doi.org/10.1016/j.emcon.2019.04.002\u003c/li\u003e\n \u003cli\u003eBlasco M, Dome\u0026ntilde;o C, Ner\u0026iacute;n C (2006) Use of lichens as pollution biomonitors in remote areas: comparison of PAHs extracted from lichens and atmospheric particles sampled in and around the Somport tunnel (Pyrenees). Environmental science \u0026amp; technology 40(20):6384-6391. https://doi.org/10.1021/es0601484\u003c/li\u003e\n \u003cli\u003eBreivik K, Armitage JM, Wania F, Sweetman AJ, Jones KC (2016) Tracking the global distribution of persistent organic pollutants accounting for E-waste exports to developing regions. Environmental Science \u0026amp; Technology 50(2):798\u0026ndash;805. https://doi.org/10.1021/acs.est.5b04226\u003c/li\u003e\n \u003cli\u003eBreivik K, Sweetman A, Pacyna JM, Jones KC (2007) Towards a global historical emission inventory for selected PCB congeners: A mass balance approach: 3: An update. Science of the Total Environment 377(2):296\u0026ndash;307. https://doi.org/10.1016/j.scitotenv.2007.02.026\u003c/li\u003e\n \u003cli\u003eCanadian Soil Quality Guidelines for the Protection of Environmental and Human Health, Summary Tables, Update 7.0 (2007)\u0026nbsp;https://support.esdat.net/Environmental%20Standards/canada/soil/rev_soil_summary_tbl_7.0_e.pdf. Accessed 10 October 2025\u003c/li\u003e\n \u003cli\u003eCarlsson P, Breivik K, Brorstr\u0026ouml;m-Lund\u0026eacute;n E, Cousins I, Christensen J, Grimalt JO, Halsall C, Kallenborn R, Abass K, Lammel G, Munthe J, MacLeod M, Odland J\u0026Oslash;, Pawlak J, Rautio A, Reiersen LO, Schlabach M, Stemmler I, Wilson S, W\u0026ouml;hrnschimmel H (2018) Polychlorinated biphenyls (PCBs) as sentinels for the elucidation of Arctic environmental change processes: A comprehensive review combined with ArcRisk project results. Environmental Science and Pollution Research 25(23):22499\u0026ndash;22528. https://doi.org/10.1007/s11356-018-2625-7\u003c/li\u003e\n \u003cli\u003eDahle S, Savinov VM, Matishov GG, Evenset A, N\u0026aelig;s K (2003) Polycyclic aromatic hydrocarbons (PAHs) in bottom sediments of the Kara Sea shelf, Gulf of Ob and Yenisei Bay. Science of the Total Environment 306(1-3):57-71. https://doi.org/10.1016/S0048-9697(02)00484-9\u003c/li\u003e\n \u003cli\u003eDanilina AE, Kutsenko VV (2000) Politika i upravlenie PHB v Rossii [Policy and Management of PCBs in Russia]. Polihlorirovannye bifenily. Supertoksikanty ХХI veka: Informacionnyj vypusk 5:5-13.\u003c/li\u003e\n \u003cli\u003eEckhardt S, Breivik K, Man\u0026oslash; S, Stohl A (2007) Record high peaks in PCB concentrations in the Arctic atmosphere due to long-range transport of biomass burning emissions. Atmospheric Chemistry and Physics 7(17):4527\u0026ndash;4536. https://doi.org/10.5194/acp-7-4527-2007\u003c/li\u003e\n \u003cli\u003eErickson MD, Kaley RG (2011) Applications of polychlorinated biphenyls. Environmental Science and Pollution Research. 18:135-151. https://doi.org/10.1007/s11356-010-0392-1\u003c/li\u003e\n \u003cli\u003eGałuszka A, Migaszewski ZM, Rose NL (2020) A consideration of polychlorinated biphenyls as a chemostratigraphic marker of the Anthropocene. The Anthropocene Review 7(2):138-158. https://doi.org/10.1177/2053019620916488\u003c/li\u003e\n \u003cli\u003eGioia R, Eckhardt S, Breivik K, Jaward FM, Prieto A, Nizzetto L, Jones KC (2011) Evidence for major emissions of PCBs in the West African Region. Environ. Sci. Technol. 45:1349\u0026ndash;1355. https://doi.org/10.1021/es1025239\u003c/li\u003e\n \u003cli\u003eGorbacheva EA, Novikov MA (2024) Hlororganicheskie soedineniya v atlanticheskoj treske (Gadus morhua) i mor skoj kambale (Pleuronectes platessa) Barenceva morya [Organochlorine compounds in Atlantic cod (Gadus morhua) and flounder (Pleuronectes platessa) of the Barents Sea]. Arctic: ecology and economy 14(4):562-574. https://doi.org/10.25283/2223-4594-2024-4-562-574.\u003c/li\u003e\n \u003cli\u003eHolma-Suutari A, Ruokoj\u0026auml;rvi P, Laaksonen S, Kiviranta H, Nieminen M, Viluksela M, Hallikainen A (2014) Persistent organic pollutant levels in semi-domesticated reindeer (Rangifer tarandus tarandus L.), feed, lichen, blood, milk, placenta, foetus and calf. Science of the total Environment 476:125-135. https://doi.org/10.1016/j.scitotenv.2013.12.109\u003c/li\u003e\n \u003cli\u003eKeith LH (2014) The Source of U.S. EPA\u0026rsquo;s Sixteen PAH Priority Pollutants. Polycyclic Aromatic Compounds 35(2-4):147\u0026ndash;160. https://doi.org/10.1080/10406638.2014.892886\u003c/li\u003e\n \u003cli\u003eKhairy M, Muir D, Teixeira C, Lohmann R (2015) Spatial distribution, air-water fugacity ratios and source apportionment of polychlorinated biphenyls in the lower Great Lakes Basin. Environmental Science \u0026amp; Technology 49(23):13787\u0026ndash;13797. https://doi.org/10.1021/acs.est.5b00186\u003c/li\u003e\n \u003cli\u003eHaustov AP, Redina MM (2016) Indikatornye sootnosheniya koncentracij policiklicheskih aromaticheskih uglevodorodov dlya geoekologicheskih issledovanij prirodnyh i tekhnogennyh ob\u0026quot;ektov [Indicator ratios of concentrations of polycyclic aromatic hydrocarbons for geoecological studies of natural and man-made objects]. Geo\u0026egrave;kologi\u0026acirc; 3:220-233\u003c/li\u003e\n \u003cli\u003eKlyuev NA (2000) Ekologo-analiticheskij kontrol\u0026apos; stojkih organicheskih zagryaznenij v okruzhayushchej srede [Ecological and analytical control of persistent organic pollutants in the environment]. Dzhejms, Moscow.\u003c/li\u003e\n \u003cli\u003eKukushkin SY (2017) Indikatory antropogennoj nagruzki na prirodno-territorial\u0026apos;nye kompleksy pri osvoenii neftegazokondensatnyh mestorozhdenij severa Zapadnoj Sibiri [Indicators of anthropogenic load on natural-territorial complexes during oil and gas condensate fields development in the north of Western Siberia]. Dissertation, Russian State Hydrometeorological University\u003c/li\u003e\n \u003cli\u003eMaliszewska-Kordybach B (1996) Polycyclic aromatic hydrocarbons in agricultural soils in Poland: preliminary proposals for criteria to evaluate the level of soil contamination. Applied Geochemistry 11(1-2):121-127. https://doi.org/10.1016/0883-2927(95)00076-3\u003c/li\u003e\n \u003cli\u003eMamontova EA, Tarasova EN, Mamontov AA, Kuzmin MI (2016) The effect of long-range atmospheric transport of organochlorine compounds by soil studies from Mongolia to the Arctic. Doklady Earth Sciences 466(2):169-172. https://doi.org/10.1134/S1028334X16020148.\u003c/li\u003e\n \u003cli\u003eMoskovchenko DV, Romanenko EA (2020) Osobennosti elementnogo sostava pochv Pur-Tazovskogo mezhdurech\u0026apos;ya [Features of the elemental composition of soils of the Pur-Taz interfluve]. Dokuchaev Soil Bulletin 103:51-84. https://doi.org/10.19047/0136-1694-2020-103-51-84\u003c/li\u003e\n \u003cli\u003eNacional\u0026apos;nyj atlas Rossii. Tom 2. Priroda. Ekologiya. [National Atlas of Russia. Volume 2. Nature. Ecology] (2007) Kartografiya, Moscow\u003c/li\u003e\n \u003cli\u003eOpekunov AY, Opekunova MG, Kukushkin SY, Ganul AG (2012) Ocenka ekologicheskogo sostoyaniya prirodnoj sredy rajonov dobychi nefti i gaza v YANAO [Assessment of natural environment ecological state of oil and gas production areas in Yamalo-Nenets Autonomous Okrug]. Vestnik of Saint Petersburg University. Earth Sciences 4:87-101\u003c/li\u003e\n \u003cli\u003eOpekunova MG, Opekunov AY, Kukushkin SY, Lisenkov SA, Vlasov SV, Somov VV (2022) Zagryaznenie pochv severa Zapadnoj Sibiri neftyanymi i policiklicheskimi aromaticheskimi uglevodorodami: raspredelenie i ocenka ekologicheskogo riska [Pollution of soils in the north of Western Siberia with oil and polycyclic aromatic hydrocarbons: distribution and assessment of environmental risk]. Eurasian Soil Science 11:1442-1460. https://doi.org/10.31857/S0032180X22110107\u003c/li\u003e\n \u003cli\u003eOpekunova MG, Opekunov AY, Kukushkin CY, Ganul AG (2019) Fonovoe soderzhanie himicheskih elementov v pochvah i donnyh osadkah severa Zapadnoj Sibiri [Background content of chemical elements in soils and bottom sediments of the north of Western Siberia]. Eurasian Soil Science 4:422\u0026ndash;439. https://doi.org/10.1134/S0032180X19020114\u003c/li\u003e\n \u003cli\u003eRobertson A (1998) Petroleum hydrocarbons. AMAP Assessment Report: Arctic Pollution Issues. Arctic Monitoring and Assessment Programme (AMAP), Oslo, Norway, pp 661-716\u003c/li\u003e\n \u003cli\u003eSharpe M (2008) 10th anniversary lecture: looking to the future of POPs. Journal of Environmental Monitoring 10(11):1259-1260. https://doi.org/10.1039/B815267P\u003c/li\u003e\n \u003cli\u003eShen H, Huang Y, Wang R, Zhu D, Li W, Shen G, Wang B, Zhang Y, Chen Y, Lu Y, Chen H, Li T, Sun K, Li B, Liu W, Liu J, Tao S (2013) Global atmospheric emissions of polycyclic aromatic hydrocarbons from 1960 to 2008 and future predictions. Environmental science \u0026amp; technology 47(12):6415-6424. https://doi.org/10.1021/es400857z\u003c/li\u003e\n \u003cli\u003eSkotvold T, Savinov V (2003) Regional distribution of PCBs and presence of technical PCB mixtures in sediments from Norwegian and Russian Arctic Lakes. Science of the total environment 306(1-3):85-97. https://doi.org/10.1016/S0048-9697(02)00486-2.\u003c/li\u003e\n \u003cli\u003eNCBI 2025. Toxicological Profile for Polychlorinated Biphenyls (PCBs). Atlanta (GA): Agency for Toxic Substances and Disease Registry (US); 2000 Nov. 4, CHEMICAL AND PHYSICAL INFORMATION.\u0026nbsp;\u003c/li\u003e\n \u003cli\u003ehttps://www.ncbi.nlm.nih.gov/books/NBK587431/. Accessed 20 August 2025\u003c/li\u003e\n \u003cli\u003eUNECE 2025. The 1998 Aarhus Protocol on Persistent Organic Pollutants (POPs).\u003c/li\u003e\n \u003cli\u003ehttps://unece.org/environmental-policy/air/protocol-persistent-organic-pollutants-pops. Accessed 13 July 2025\u003c/li\u003e\n \u003cli\u003eUNEP 2001. Stockholm Convention on POPs, Text and Annexes, Interim Secretariat for the Stockholm Convention on Persistent Organic Pollutants. Geneva: UNEP Chemicals. https://chm.pops.int/portals/0/repository/convention_text/unep-pops-cop-convtext-full.english.pdf. Accessed 13 July 2025\u003c/li\u003e\n \u003cli\u003eVolkova NA, Ivanova IS, Sokolov DA, Kolubaeva YV, Chujkina DI (2023) Koncentracii i istochniki policiklicheskih aromaticheskih uglevodorodov v vode i donnyh otlozheniyah rek severnyh neftegazodobyvayushchih territorij Zapadnoj Sibiri [Concentrations and sources of polycyclic aromatic hydrocarbons in water and bottom sediments of rivers in the northern oil and gas producing areas of Western Siberia]. Bulletin of the Tomsk Polytechnic University. Geo Assets Engineering 334(4):135-148. https://doi.org/10.18799/24131830/2023/4/3924\u003c/li\u003e\n \u003cli\u003eVorkamp K (2016) An overlooked environmental issue? A review of the inadvertent formation of PCB-11 and other PCB congeners and their occurrence in consumer products and in the environment. Science of the Total Environment 541:1463-1476. https://doi.org/10.1016/j.scitotenv.2015.10.019\u003c/li\u003e\n \u003cli\u003eWania F, Mackay D (1996) Peer reviewed: tracking the distribution of persistent organic pollutants. Environmental science \u0026amp; technology 30(9):390A-396A. https://doi.org/10.1021/es962399q\u003c/li\u003e\n \u003cli\u003eWilcke W (2007) Global patterns of polycyclic aromatic hydrocarbons (PAHs) in soil. Geoderma 141(3-4):157-166. https://doi.org/10.1016/j.geoderma.2007.07.007\u003c/li\u003e\n \u003cli\u003eWilcke W (2000) Synopsis polycyclic aromatic hydrocarbons (PAHs) in soil\u0026mdash;a review. Journal of plant nutrition and soil science 163(3):229-248. https://doi.org/10.1002/1522-2624(200006)163:3%3C229::AID-JPLN229%3E3.0.CO;2-6\u003c/li\u003e\n \u003cli\u003eWilcke W, Amelung W (2000) Persistent organic pollutants in native grassland soils along a climosequence in North America. Soil Science Society of America Journal 64(6):2140-2148. https://doi.org/10.2136/sssaj2000.6462140x\u003c/li\u003e\n \u003cli\u003eWolska L, Mechlińska A, Rogowska J, Namieśnik J (2014) Polychlorinated biphenyls (PCBs) in bottom sediments: Identification of sources. Chemosphere 111:151-156. https://doi.org/10.1016/j.chemosphere.2014.03.025\u003c/li\u003e\n \u003cli\u003eYanin EP (1997) Polihlorirovannye bifenily v okruzhayushchej srede (ekologo-gigienicheskie aspekty) [Polychlorinated biphenyls in the environment (ecological and hygienic aspects)], Dialog MGU, Moscow\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Arctic, POP, PAH, PCB, soil, bottom sediments, pollution","lastPublishedDoi":"10.21203/rs.3.rs-8209042/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8209042/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eAssessment of environmental pollution in the Arctic is becoming increasingly important in the terms of active industrial development and global climate change. Soils and bottom sediments from the northern regions of Western and Central Siberia were analyzed for persistent organic pollutants including polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). Total concentrations were calculated and trends in the relative distribution of individual PAH and PCB groups were identified in soils and bottom sediments across Arctic subregions defined by CAFF. Potential pollution sources were identified using nonmetric multidimensional scaling (nMDS). The characteristics of lake bottom sediment pollution due to oil and gas production were examined. Total PAHs in soils and bottom sediments of background areas ranged from 0.3 to 112.6 \u0026micro;g/kg dry weight, increasing northward. Total PCBs ranged from 0.2 to 9 \u0026micro;g/kg dry weight, regardless of the subregion. It was shown that PAH contamination occurred predominantly from light 2- and 3-ring compounds. Ordination using non-metric multidimensional scaling showed a decrease in the diversity of PAH compositions in the studied background soils and bottom sediments depending on latitude and distance to the nearest industrial center, which reflects the influence of climate and atmospheric transport. In comparison to background values, lake bottom sediments in the oil and gas production areas showed an increase in the overall content and fraction of heavy PAHs. No significant differences were found in the total content or composition of PCBs in lake bottom sediments from oil and gas production areas compared to background levels.\u003c/p\u003e","manuscriptTitle":"Content and Potential Sources of Pahs and Pcbs in Soils and Bottom Sediments of the Siberian Arctic","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-12-05 14:30:47","doi":"10.21203/rs.3.rs-8209042/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"81850c47-32ae-4aeb-953d-089efed1aa98","owner":[],"postedDate":"December 5th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-12-09T18:35:20+00:00","versionOfRecord":[],"versionCreatedAt":"2025-12-05 14:30:47","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8209042","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8209042","identity":"rs-8209042","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}