The Western Siberian peatlands rank among the largest in the Northern Hemisphere. This study investigates peatland development and palaeohydrological changes of the Mukhrino mire during the Holocene focussing on climatic, regional and local factors. The multiproxy and multi-core approach reveals spatial variability driven by topography and sedimentary conditions. Our study integrates testate amoebae, plant macrofossils, peat geochemical and biomarkers to provide insights into past vegetation and environmental conditions. Peat accumulation in Mukhrino mire began in the early Holocene, with regional vegetation influenced by climatic and soil factors. Forest cover has been present since the Early Holocene. Birch and pine dominated in the drained areas and episodic regional presence of Tilia and Ulmus indicated warmer intervals. Since ~8800 cal yr BP, Mukhrino mire transitioned to an oligotrophic/ombrotrophic state dominated by Sphagnum fuscum . A key focus of this study is the dynamics of peatland surface wetness over millennia. Proxy-specific responses revealed both short-term variability (via testate amoebae) and long-term climatic trends (via plant macrofossils). Local dry phases (~6500–5700/4700 and 2200–1800 cal yr BP) resulted in partial mire afforestation, while wetter periods (~5700/4700–2500 cal yr BP) facilitated the restoration of its current state. Comparisons with prior studies identified two wet and four dry zones, with synchronised wetness trends across cores despite localised variations in peat accumulation rates. A pronounced local wet phase (~6700–6800 cal yr BP) corresponds with a marker layer from nearby Lake Svetlenkoye sediments (~8000–6700 cal yr BP), attributed to Ob River palaeo-floods. This evidence supports the presence of regionally wet environmental conditions during this period.

This study investigates the molecular composition of a Holocene oligotrophic sapric peat core from the Mukhrino Carbon Supersite in Western Siberia, with special reference to carbon pool stabilization mechanisms. Using 13C NMR spectroscopy and elemental analysis, we analyzed peat samples across depth gradients to assess organic matter transformation and stability. Results revealed distinct variations in aromaticity, hydrophobicity, and elemental composition with depth, indicating increasing organic matter stabilization in deeper layers. The study highlights the vulnerability of surface peat layers to mineralization under climate change, emphasizing the critical role of Siberian peatlands in global carbon balance. The findings provide insights into peatland carbon dynamics and underscore the need for conservation strategies to mitigate potential carbon emissions from these ecosystems

Oligotrophic bogs are presented by a combination of microlandscapes with varying water tables and vegetation. The variability of these features may influence the rate of plant residue decomposition and the efficiency of biogenic compounds accumulation. These processes affect the formation of the microlandscape hydrochemical system and the bog. This study examines the variability of hydrochemical features in the main microlandscapes of the Mukhrino oligotrophic bog, located in the middle taiga subzone of Western Siberia. The study aim was to identify the distinctive features of bog water composition. The measured properties included concentrations of cations (Na+, NH4+, K+, Mg2+, Ca2+) and anions (Cl–, SO42–, PO43–, NO3–) dissolved organic carbon (DOC) and its spectral characteristics (SUVA254) . The dominant ions in the water are Na+ и K+ and Cl⁻ and Cl– и SO42–. Relative to the total measured ion concentrations, the ecosystems form the following order of increasing compound concentration: ryam-hollow complex (RHC) – open bog – ridge-hollow-pool complex (RHPC) – ridge-hollow complex (RHC) – typical ryam. A hydrochemical feature of the RHK is high DOC concentrations with low ion content. The open bog ecosystems are characterized by a cation composition dominated by K+ and NH4+. The GHPC exhibit elevated SO42– in the anionic composition, whereas the RHC areas show higher Cl–. concentrations. However, the waters of both ecosystems demonstrate low dissolved organic carbon (DOC) concentrations (71.3 and 66.1 mg/L, respectively). The typical ryam stands out with the highest DOC (85,8 mg/L) and measured ion concentrations.

Peatlands are a major source of dissolved organic carbon (DOC) for inland waters in Western Siberia. Continuous hydrological and hydrochemical monitoring of these peatlands is essential for understanding the global carbon cycle. We investigated a pristine ombrotrophic bog in Western Siberia to determine the links between seasonal hydrological changes and DOC quantity and quality. Specifically, we analysed water table fluctuations, DOC concentrations and spectral characteristics (SUVA~254~, E2:E3 and E4:E6 ratios). Our findings indicate that each peatland ecosystem exhibits distinct seasonal hydrochemical changes. The driest ecosystems (ryams) feature water with the highest DOC concentrations, characterised by high aromaticity and large molecular size, whereas the wettest ecosystems (pools) display the opposite trend. Surprisingly, the stream, which collects water from the entire peatland catchment, exhibits unique properties in that its DOC concentration is similar to that of wet ecosystems, while its spectral features more closely resemble those of dry ecosystems. Therefore, peatland ecosystems act as complex biogeochemical systems, modulating both the concentration and quality of dissolved organic carbon (DOC) based on prevailing environmental conditions.

Aim: To study the dynamics of specific greenhouse gas (CO2 and CH4) fluxes in a ridge-and-moss oligotrophic bog complex in the middle taiga subzone of Western Siberia taking into account their spatial heterogeneity under the influence of environmental factors, to reveal the degree of influence of meteorological parameters on greenhouse gas fluxes, and to establish quantitative relationships between the observed fluxes of carbon dioxide and methane. Methods: Greenhouse gas fluxes were measured using the chamber automatic monitoring system with eight transparent chambers and CO₂, CH₄ and H₂O gas analyzer. Results: The mean values of CO2 and CH4 fluxes from bog surface were obtained; differences in the functioning of the ridge and the hollow are shown: median values of CO2 fluxes indicate a greater uptake on the ridge (-74.4 mgCO2/m2/h) than on the hollow (-52.7 mgCO2/m2/h); methane fluxes on the ridge (0.08 mgCH4/m2/h) are on average 20 times lower than on the hollow (2.76 mgCH4/m2/h). Correlation of greenhouse gas fluxes with environmental factors were revealed: the highest correlations were found with the intensity of incoming solar (r = -0.84 ÷ -0.91) and photosynthetically active radiation (r = -0.85 ÷ -0.92), air temperature (r = -0.51 ÷ -0.63) and relative air humidity (r = +0.56 ÷ +0.62). Conclusions: Correlations between specific greenhouse gas fluxes were studied based on spatial and temporal flux variability data. Correlations between greenhouse gas fluxes are different at night and daytime, which is directly related to environmental factors.

Global climate change is one of the most important and promising phenomena to study in actual time. One of the key causes of global climate change is increasing the greenhouse gas (GHG) concentrations in the atmosphere [IPCC, 2023]. The main greenhouse gases are methane, carbon dioxides and nitric oxide, which contribute to the greenhouse effect and global warming [Lashof, Ahuja, 1990]. Carbon dioxide (CO2) is one of the most significant and widespread gases involved in the planet's global carbon cycle [Lashof, Ahuja. 1990]. At the same time, living organisms play a key role in creation of atmosphere composition. Autotrophic organisms use a carbon dioxide to build their body structures, including complex organic compounds. During ecosystem functioning, the part of the carbon dioxide is released into the atmosphere through organism respiration, while another part is released through the decomposition of dead organic matter. Carbon dioxide may also be produced through natural and anthropogenic processes. Peatland ecosystems play a significant role in the planet's carbon cycle, both locally and globally. Peatlands in their natural undisturbed state are a significant long-term carbon sink1. However, the process of carbon deposition is not constant – in different years, peatlands may serve either as carbon sink or source2. The main factor stimulating the carbon sequestration by peatland ecosystems is climatic conditions [Harenda et al., 2018; Bond-Lamberty et al., 2018]. Peatlands are the second most significant carbon stock on Earth and the largest on land. Despite covering only 2.84% of the Earth's land surface, the amount of soil organic carbon stored in them accounts for about one-third of all soil organic carbon on Earth. Peatlands in the northern hemisphere play a particularly important role in carbon sequestration, with an estimated accumulated carbon quantity of ~473–621 Gt of carbon [Yu et al., 2010]. The largest area of peatlands in Russia is located in Western Siberia, estimated at ~42% of the total Russian area [Vomperskiy et al., 1994; Sheng et al., 2004]. The territory of Western Siberia is featured to a high share of peatlands in original undisturbed state, making them an ideal location to study the impact of global changes on peatland biogeochemical functioning worldwide. The carbon balance of peatlands is mainly determined by two processes: photosynthesis and respiration [Harenda et al., 2018]. The main factors influencing the CO2 flux from peatlands are photosynthetically active radiation, atmospheric air temperature (Tavg), soil temperature (Tsoil), and water table level (WTL) [Miao et al., 2013; Juszczak et al., 2013; Dyukarev et al., 2019]. At the same time, the level of mutual influence and the degree of determination have not yet been fully determined. To study the carbon balance of terrestrial ecosystems, the chamber method [Davidson et al., 2002] is widely used. The chamber method allows to estimate the CO2 flux from the surface of the ecosystem. At the same time, the use of the modern automatic system LI-COR LI-8100A (LI-COR, USA) provides high-frequency continuous data on carbon dioxide fluxes over a long period of time, which makes it possible to assess the total accumulation of carbon and significantly improve the reliability of the identified relationships with environmental factors [Zarov et al., 2022]. The purpose of this study was to assess carbon dioxide flluxes and discover the main hydrometeorological parameters that influence the flow in the hollows of the Mukhrino raised bog. MATERIALS AND METHODS The research was carried out at the «Mukhrino» field station [Dyukarev et al., 2021], located in the central part of Western Siberia, 30 km southwest of the city of Khanty-Mansiysk. The climate is featured by high repeatability of anticyclonic conditions, rapid changes in weather conditions, a humid, moderately warm summer, and a fairly harsh, snowy winter. The chamber system was installed in a homogeneous area of the peatland, dominated by Sph. balticum, C. limosa, and Scheuchzeria palustris, with the presence of E. vaginatum on the periphery. The plant composition inside the chambers was not determined, but the most homogeneous and similar areas were selected for installation (Figure 2). Carbon dioxide flux measurements were carried out using the automated chamber method, using a portable soil respiration analysis system LI-8100A (LI-COR, USA). The flues were measured by four automated chambers installed in the raised bog area of Mukhrino (Figure 3). The first group of chambers – NEE (2 LI-COR 8100-104s chambers), measured net ecosystem exchange (NEE); the second group – Reco (2 LI-COR 8100-104 cameras), measured ecosystem respiration (Reco). Measurements were taken for 2 minutes every 30 minutes for all cameras. Wooden walkways were installed in the peatland area to minimize potential negative impacts on the study surface. The fluxes were calculated using a linear model of specialized software LI-8100 File Viewer 3.0.0 (LI-COR). R programming language packages dplyr [Wickham, 2016], ggplot2 [Wickham, 2016], lubridate [Grolemund, Wickham, 2011] were used for data processing and visualization. To analyze the dynamics of NEE and Reco fluxes, the obtained values were averaged between LI-COR 8100-104s chambers (for NEE) and LI-COR 8100-104 chambers (for Reco). Gross primary production (GPP) was calculated using the equation GPP=NEE-Reco [Connolly et al., 2009]. For further analysis, measurements with a coefficient of determination (R2) of linear regression above 0.5 were selected to minimize significant noise in the data. Spearman's rank correlation method was chosen to identify dependencies of flux on hydrometeorological properties. The dependence was determined based on the data of the flux and hydrometeorological properties averaged over 30 minutes. RESULTS AND DISCUSSION The average daily variation of CO2 flows for July, September, October 2021 is shown in Fig. 5. The simultaneous use of dark and light chambers allowed to assess the flows that are released in the ecosystem as a result of the respiration of plants, animals and microorganisms (Reco), the intensity of CO2 absorption in the process photosynthesis (GPP), and net ecosystem exchange (NEE), which is the difference between the specific absorption rate (GPP) of carbon dioxide excretion (Reco). The average daily variation of Reco (Fig. 5) in July was featured by the highest values during daylight hours; the CO2 flux reaches its maximum value at 11:00 (1.44 µmol m‑2s‑1). For September and October, the daily dynamics of Reco were weakly expressed. The highest CO2 emissions were typical for evening and night time. The maximum Reco in the daily cycle was observed at 19:00 (0.47 µmol m‑2s‑1) for September, and at 00:00 (0.17 µmol m‑2s‑1) for October. The average daily cycle of GPP (Fig. 5) had a pronounced absorption maximum during daylight hours with maximum radiation, for July – at 11:00 (-3.47 µmol m‑2s‑1), for September – at 12:00 (-1.53 µmol m‑2s‑1), for October – at 11:00 (-0.45 µmol m‑2s‑1). The absorption of carbon dioxide from the atmosphere (GPP) had different daily durations depending on the month (Fig. 5), which is associated with a decrease in daylight hours by autumn. In July, carbon dioxide absorption was observed from 4:00 to 20:00 (16 hours), in September – from 5:00 to 18:00 (13 hours), in October – from 7:00 to 17:00 (10 hours). For the diurnal cycle of NEE (Fig. 5), the CO2 absorption process (GPPReco) predominated in the daytime, while the carbon dioxide emission process (GPPReco) dominated at night. The maximum NEE value in the daily cycle in July was estimated at 1.01 µmol m‑2s‑1 at 22:00, in September 0.49 µmol m‑2s‑1 at 20:00, in October 0.17 µmol m‑2s‑1 at 21:00. The minimum NEE value in July was -2.03 µmol m‑2s‑1 at 11:00, in September: -1.01 µmol m‑2s‑1 at 12:00, in October 0.39 µmol m‑2s‑1 at 11:00. A total of 1711, 2625 and 1597 Reco measurements were taken in July, September and October, respectively. The highest average daily rate of ecosystem respiration Reco occurred in the third ten days of July (July 19); by the last days of October, ecosystem respiration reached its minimum in the annual course (Fig. 7). The average Reco in July was 1.05±0.25 µmol m‑2s‑1, and in October 0.13±0.01 µmol m‑2s‑1. These estimates were obtained on a sufficient array of data and therefore can be considered reliable. The peak intensity of photosynthesis was recorded on July 22, when vegetation absorbed the largest amount of CO2. After July 22, there was a gradual decline in GPP; the rate of carbon dioxide absorption in the last days of October decreased significantly, but did not drop to zero. The presence of photosynthesis in the hollow of an oligotrophic bog even in late autumn and at low air temperatures is probably due to the activity of sphagnum mosses. Net ecosystem exchange (Fig. 7) was negative every day in July, thereby the absorption of carbon dioxide from the atmosphere daily dominated its release. In September, ecosystem absorption of carbon dioxide prevailed until September 10, after which both negative and positive NEE values were observed. During this period, intense precipitation occurred, a decrease in air temperature and the amount of incoming radiation, which led to the ecosystem switching from a sink to a temporary source of CO2. In October, the number of days on which the ecosystem acted as a carbon sink decreased; on most days, carbon dioxide emissions predominated. According to average monthly values, carbon dioxide absorption prevailed in July (-0.53±0.13 µmol m‑2s‑1) and September (-0.11±0.18 µmol m‑2s‑1), in October (0.02±0.04 µmol m‑2s‑1) CO2 evolution predominated. The number of measurements according to NEE (Table 2) is greatest in September (2584) and least in July (1709). Reco was most influenced in July (Table 3) by air and soil temperature; in September – soil temperature and marsh water level. In October, when daily temperature variability decreased, the most significant factor for Reco was PAR (-0.59). The degree of correlation of Reco with Tavg and Tsoil in July qualifies as high; these factors are directly related to Reco – the higher the temperature, the greater the release of carbon dioxide into the atmosphere by the ecosystem. This is caused by an increase in the activity of microorganisms under the influence of increased temperature [Nikonova et al., 2019]. In September, the influence of Tsoil (0.81) and water level (-0.78) increased, while the influence of Tavg (0.54) decreased. The degree of correlation of these parameters with Reco in September was classified as high. It is assumed that the strong influence of water level (-0.78) on the Reco flux in September may be associated with a sharp rise in water level (Fig. 6F), which could lead to a disruption of the optimum life activity of microorganisms. Similar flow behavior was found for North American peatlands [Miao et al., 2013]. In October, the greatest influence on Reco was exerted by PAR (-0.59), the degree of correlation is weak negative; At the same time, the correlation of the indicator with PAR in July was weakly positive. The highest correlation for GPP (Table 3) was obtained with photosynthetically active radiation for all months of the study. The PAR correlation level for all months was classified as high. The inverse correlation is due to the fact that as PAR increases, CO2 absorption increases (negative GPP flux). PAR is a key factor influencing plant photosynthesis, which in turn affects their ability to assimilate CO2 and produce GPP. As PAR intensity increases, plants increase the rate of photosynthesis and absorb carbon dioxide from the atmosphere faster, which increases GPP. The greatest influence on NEE was caused by PAR (Table 3) in July, in September and October (-0.91, -0.74 and -0.71, respectively). The level of PAR correlation in July and September was high, in October it was moderate. When PAR levels increase, plants use carbon dioxide more actively to produce organic matter and increase the level of GPP in the ecosystem, which leads to an increase in NEE flux. On the other hand, when PAR levels decrease, plants become less active in photosynthesis, which leads to the prevalence of Reco and a decrease in NEE flux. Analysis of correlation coefficients calculated from data for the entire field season, the best relationship for Reco was found with soil temperature (0.88), air temperature (0.71) and water level (-0.73). PAR has the greatest influence on GPP (-0.89) and NEE (-0.73). CONCLUSIONS Automated high temporal resolution chamber measurements of carbon dioxide flux provided a data for analyzing CO2 fluxes in the peatland area. The results provided detailed information that was used to analyze the impact of environmental hydrometeorological parameters on the flux. The highest ecosystem respiration (Reco) value during a 24-hour period was recorded in July at 11:00 (1.44 µmol m‑2s‑1), in September at 19:00 (0.47 µmol m‑2s‑1), and in October at 00:00 (0.17 µmol m‑2s‑1). The maximum gross primary production (GPP) for all months occurred between 11-12 hours: in July at 11:00 (-3.47 µmol m‑2s‑1), in September at 12:00 (-1.53 µmol m‑2s‑1), and in October at 11:00 (-0.45 µmol m‑2s‑1). By autumn, the duration of GPP throughout a day decreased, as well as the amplitude of diurnal variation for all flux indicators. The highest average daily CO2 flux for all indicators was recorded in July, while the lowest was in October. In net ecosystem exchange (NEE), absorption predominated from July 14 to September 9, with days dominated by ecosystem respiration from September 10 onwards. The amplitude of the average daily flux for all indicators decreased by October. Based on the Spearman correlation data, the highest seasonal correlation for ecosystem respiration (Reco) was with soil temperature (0.88), air temperature (0.71), and water level (-0.73). In July, the best correlation is with air temperature (0.70) and soil temperature (0.68), in September with soil temperature (0.81) and water level (-0.78), and in October with photosynthetically active radiation (PAR) (-0.59). Gross primary production (GPP) correlates best with PAR. In July, the correlation coefficient is -0.95, in September -0.86, in October -0.79, and for the entire field season -0.89. Net ecosystem exchange (NEE), similar to GPP, is most dependent on PAR. In July, the correlation coefficient is -0.91, in September -0.74, in October -0.71, and for the entire field season -0.73. In general, the article calculates carbon dioxide fluxes from the surface of a hollow in an oligotrophic peatland. The seasonal and average daily dynamics of hydrometeorological properties are described, and their influence on CO2 flows is assessed. It is worth noting that throughout the entire growing season, the influence of external factors on fluxes decreases, reaching a minimum mutual correlation in the coldest month (October).

We studied the peat stratigraphy of the Mukhrino peatland, which is a typical ombrotrophic bog for the Middle Taiga zone of Western Siberia, to gain insights into its history, hydrology, and carbon fluxes. For the first time in Western Siberia, seven cores were collected from locations that were chosen to represent the typical present-day vegetation types, and this was performed for the dating of the separated dissolved (DOC) and particulate organic carbon (POC) fractions, which were determined using the Accelerator Mass Spectrometer (AMS) radiocarbon (14C) method. The oldest peat was found at the bottoms of an underlying lake (10,053 cal. year BP) and an ancient riverbed (10,989 cal. year BP). For the whole history of the peatland, the average peat accumulation rate was estimated to be 0.067 ± 0.018 cm yr−1 (ranging from 0.013 to 0.332 cm yr−1), and the carbon accumulation rate was 38.56 ± 12.21 g m−2 yr−1 (ranging from 28.46 to 57.91 g m−2 yr−1). There were clear age differences between the separated samples of the DOC and POC. The DOC was older than the POC in the uppermost 150 cm of the peat deposit and younger in the deeper layers. The difference in age increased with depth, reaching 2000–3000 years at the bottom of the peat deposit (depth of 430–530 cm). Following the consideration of a range of factors that could potentially cause the dating discrepancy, we hypothesised that the DOC continuously moves down into the mineral sediment beneath the peat, as an additional carbon flux that results in the mixing of younger and older carbon. On this basis, we estimated the apparent rate of the DOC’s downward movement and the associated rate of carbon loss. The first estimate of the average rate of the DOC’s downward movement in Western Siberia was 0.047 ± 0.019 cm yr−1, causing carbon loss in the range of 28–404 mg m−2 yr−1.

PeatlandPeatland streams have repeatedly been shown to be responsible for the high amounts of produced in the soil ecosystems dissolved organic carbonDissolved organic carbon (DOC) exported to the Arctic rivers. They contribute to the global carbon budget and remove carbon amounts equal to 50

Introduction. The concentration of methane in the Earth's atmosphere, the second most potent greenhouse gas, continues to rise since 2007 [Canadell et al., 2021]. The need to significantly reduce the anthropogenic emission of methane into the atmosphere in order to limit the increase in global temperature by 2100 within 2C relative to the period from 1850 to 1900 is recognized by both the scientific community [IPCC, 2021] and the leadership of most countries of the world, including Russia, who signed and ratified the Paris Agreement, adopted following the results of the 21st Conference of the UN Framework Convention on Climate Change [Climate Agenda of Russia, 2021]. Reduction of methane emissions and control over it throughout the territory of managed ecosystems will require huge resources and investments, development of new climate-smart technologies. A reasonable compromise may be to identify the most important sources of methane within managed ecosystems (also called hot spots) and to introduce changes in their land-use in accordance with the principles of sustainable development and science-based environmental management. The major type of economic activity in the taiga natural zone of West Siberia is oil production [Koleva, 2007; Volkova, 2010]. Since 35-40% of the West Siberian middle taiga area is covered with waterlogged ecosystems - wetlands and floodplains [Peregon et al., 2009; Terentieva et al., 2016], a significant part of this infrastructure is located in wetland ecosystems and has a strong impact on them. In this paper, we made the first attempt to understand, how the most common types of disturbances by oil production (road, pipeline and electric power transmission line construction) can affect methane emissions from the most common disturbed waterlogged ecosystems in the region (oligotrophic raised bogs on a terrace or watershed) and eutrophic lowland swamps in the floodplain). We measured methane emission from the surface of disturbed wetland ecosystems, physicochemical and biological factors influencing it, to identify which ecosystems are hot spots of methane emission. Objects. The study area was located 50 km southeast of the city of Khanty-Mansiysk, on the right bank of the Irtysh River, in the natural zone of the middle taiga. The climate of this region is subarctic (Dfc according to Kppen). In the floodplain of the Irtysh the most common types of wetlands are sedge-grass open swamps and sogras (treed sedge-grass wetlands), on terraces and the watershed - pine-shrub-sphagnum ecosystems (ryams) and ridge-hollow complexes [Liss et al., 2001]. The thickness of the peat layer in raised bogs on the terrace and watershed varied from 2 to 3 m; in sogra from 3.5 to 4 m; in open floodplain swamps thickness of organic-rich horizon never exceeded 0.4 m. For floodplain ecosystems we investigated influence of a four-lane access road on changing the hydrological functioning of open swamps (points OO and OK), as well as the effect of cross-cut in a sogra (SP) compared to an undisturbed sogra (SE). For raised bogs on the terrace and watershed, we study the influence of asphalt two-lane roads which act as dams, preventing the flow of water from one side of the road to the other resulting in flooding to upstream areas (GMKO1 and GMKO2) and drying in downstream areas (GMKS) in ridge-hollow complexes. In ryams and ridge-hollow complexes The effect of cross-cutting on methane emission in ryams (RP1 and RP2) as well as pipeline installation in ryam (RTO1) and ridge-hollow complex (RTO2) were also studied. During a cross-cut tree layer was destroyed, the vegetation and moss cover was compacted (RP1) or mostly destroyed (RP2 and SP). Access roads were constructed 3 (four-lane) and 10-15 (asphalt two-lane) years ago. Pipelines were installed 2-3 years ago. Methods. Methane flux was measured using the static chamber method [Hutchinson and Mosier, 1981]. In the course of one flux measurement four syringes were taken from the chamber on the interval of 10 min. Total duration of one flux measurement was 30 minutes. Three consecutive replicates of the flux measurements were carried out on each of the three collars per each investigated ecosystem. Interval between two consecutive flux measurements was 10 min. Water were sampled from the depth of 20 cm below water table level (WTL) in two replicates to determine dissolved organic carbon (DOC) content at the points GMKO2, GMKS, RTO1, RTO2, RP2, as well as in an undisturbed ryam ecosystem 50 m away from the points RTO1 and RP2. The concentration of DOC was measured by a Flash 2000 elemental analyzer using an AS1310 automatic liquid sampler (both Thermo Fisher Scientific, USA). In each studied ecosystem for each collar the values of WTL (cm, positive water is below the level of the moss surface), pH and electrical conductivity (Scm-1) of water were measured. All calculations were carried out in the MATLAB software environment R2022a (MathWorks, USA). Results and discussion. Methane emission varied from 0.005 to 41.7 mgm-2h-1 with a median of 2.1 mgm‑2h‑1. Fluxes were not distributed normally (p 0.0001, N = 33), but could be described by the lognormal distribution (p = 0.15) and the Weibull distribution (p = 0.22). Such a significant distribution asymmetry indicates that changes of land-use practice in several ecosystems with the highest methane emission could help to reduce methane emission significantly without substantial modifications of the whole landscape. The dependence of the methane flux on WTL differs depending on both disturbance and ecosystem types. Within one ecosystem, the maximum emission values can be observed both in most flooded sites (RP2, GMKS), in sites with intermediate WTL values (GMKO1, RTO2, OK), and in sites with the highest WTL (RTO1). One of the markers of methane emission hot spots is the appearance of ruderal plants Eriophorum vaginatum and Trichophorum cespitosum in different ecosystems and on disturbances of different types. Eriophorum vaginatum is one of the first species to settle on bare peat in cross-cuts (RTO1 and RTO2) and footprints after heavy equipment (RP2) in raised bogs, as well as on seismic survey lines in sogra (SP). Trichophorum cespitosum was found in the upstream area of the road, where a zone of excessive moisture has formed resulting in degradation of the moss and vegetation cover and peat decomposition (GMKO1). In all these five ecosystems, methane flux from sites covered with Eriophorum vaginatum and Trichophorum cespitosum was 2 or more times higher compared to the surrounding sites where these species were absent. The maximum values of methane emission among all studied ecosystems are in the WTL range from -2 to 8 cm (see Fig. 1). In studied raised bogs, the emission from the flooded upstream areas (GMKO1 and GMKO2) was significantly lower (p = 0.0082, N = 8) than from the dried downstream areas (GMKS), if we exclude the point with Trichophorum cespitosum, where high methane emission is attributed, presumably, to the influence of the plant community and not with to the different WTL, as described in the section above. In contrast, for floodplain wetlands, emission from the open sedge bog in the drying area (OO) was significantly lower (p = 0.02, N = 6) than from the flooded open swamp with Phalaris arundinacea (OC). This difference could be explained by changes in local ecohydrology and hydrochemistry after the road construction. Methane emission from ridges in GMKO1 and GMKO2 ecosystems (median 1.5 mgm-2h-1) exceeds by an order of magnitude the median of methane emission from middle taiga ridges Western Siberia (0.13 mgm-2h-1 according ‑to [Kleptsova et al., 2010]). Due to flooding in the upstream area of the roads, WTL in ridges decreased compared to values typical for these ecosystems (mean standard deviation is 35 14 cm according to [Kleptsova et al., 2010]). However, the grass-moss layer of the ridges did not degrade, and the methane emission from them turned out to be comparable with the emission from undisturbed ridges with the same WTL values (Fig. 2). Methane emission from temperate and subarctic swamps is typically characterized by a lower optimal WTL value (ranging from -20 cm to -5 cm) compared to bogs [Bao et al., 2021]. Therefore, flooding of the Phalaris arundinacea swamp (OK) resulted in optimal conditions for methanogenesis in all three studied sites of this ecosystem with WTL ranging from -12 to 3 cm. The methane emission in each site of the Phalaris arundinacea swamp was higher than the third quartile for the entire sample obtained in this study. The open sedge bog (OO) separated from the rest of the floodplain by the road was characterized by a higher WTL (from -5 to 12 cm), far from optimal. In addition, the soil temperature in these ecosystems, located at a distance of 600 meters from each other, differed by 9-11C in a peat layer from 0 to 20 cm. The same pattern was observed in sogra wetland, where temperature of the upper 20 cm in cross-cut bare peat was 6-8C higher than in undisturbed site, separated from floodplain by access road. Thus, both the temperature and hydrological regimes contribute to the fact that the methane emission from the flooded floodplain open swamp (OK) is significantly higher than from the floodplain bog in the drying area (OO point). A similar pattern was observed for the treed floodplain swamp (SP and SE points, respectively). The concentration of DOC in the water of natural and disturbed ecosystems of the low ryam was significantly higher than in the hollow of the ridge-hollow complex (p 0.01, N = 5). The same pattern was observed for Canadian wetlands and was explained by the fact that DOC production occurs mainly in the aeration zone above the WTL. Since in ryams and ridges WTL it is higher than in hollows, the rate of plant litter decomposition is twice as high as in hollows (Moore, 2009). The higher rate of decomposition can explain both the higher EC (faster mineralization) and the lower pH (higher acidogenesis) in the low ryam. It is noteworthy that during the disturbance and subsequent recovery of the vegetation in the ryam, the concentration of DOC in the peat pore water increased by almost one and a half times, while in the hollow of the ridge-hollow complex it did not change considerably compared to the value in undisturbed wetland ecosystem. Conclusion. Measurements of methane emission from wetlands of the West Siberian middle taiga disturbed during oil production and its physicochemical and biological factors showed that several of these ecosystems are intensive sources of this greenhouse gas. Although this is only a snapshot taken at the end of June 2021, and it is necessary to study the seasonal dynamics of the methane flux for more reliable conclusions, several indicators of methane emission hot spots could be suggested. Presence of ruderal plants such as Eriophorum vaginatum and Trichophorum cespitosum marks such a hot spots throughout different ecosystems. Ecosystem-specific range of WTL optimal for methane emission could also be a reliable indicator of these hot spots. Response of methane emission to the construction of roads depends on type of wetland ecosystems. In raised bogs, hollows in the upstream area emit less methane than undisturbed ecosystems, while in the downstream area emission is higher. Emission from ridges in flooded ridge-hollow complexes increases with the decrease of the WTL in them, similarly to natural undisturbed ridges. Nutrient-rich floodplain swamps response differently to changes in the hydrological regime. The emission of methane from open and forested swamps in the drying area is lower than from flooding area. This is explained not only by different WTL optimums for methane emission between bogs and swamps but also differences in temperature (6-11С) of the surface organic-rich layers of floodplain wetlands in the flooding area compared to drying area. The methane emission from heavy vehicle tracks in low ryam is driven by the change in WTL relative to its optimum for methane emission from raised bogs.

This article provides a historical review of the peatlands study in the Middle and South taiga, as well as Subtaiga zone of Western Siberia, and summarizes the data on the structure of peat deposits in mires of the region, accumulated by the senior author over many years of field research (1980-2004). The features of the main types of stratigraphic structure, as well as a description of the development history of peat mires, are given based on a detailed study of macrofossil composition of peat cores and peat sections. Peat cores were selected within the landscape-ecological profiles, covering all relief elements from the raised bogs of the watershed plains to the mires of river valleys and gullies of ancient water runoff in different climatic zones and subzones (Subtaiga, Southern taiga and Middle taiga). The oldest peat deposits are associated with the deep thalwegs and ancient hydrological system. Peat formation started simultaneously within the taiga zone and the present subarctic zone of Western Siberia and reached the high distribution level in Boreal period. The peatlands development process tightly followed the climate humidity in the wet periods, the watershed mires actively developed and floodplain mires development was constrained by the alluvial deposition process; in the dry periods, the floodplain mires developed actively and the watershed mires grow was stagnated.

Based on the experimental data, soil carbon and nitrogen stocks are estimated in polygonal-fissure mires of southern tundra in the north-eastern part of Western Siberia. The field experiments were carried out in 2014-2017 at the site located in tundra zone of the Yamal-Nenets Autonomous District. Active soil layer (seasonally thaw) and upper frozen layer are investigated. The seasonally thaw layer of tundra soils has been subdivided into two horizons: active upper layer (down to 15 cm depth) and active lower layer (from 15 cm down to the permafrost). Our research has shown that the values of organic carbon and total nitrogen storages in mires under study can be estimated as 14.1±3.6 kgC/m 2 and 0.4±0.1 kgN/m 2 for the active soil layer and 12.9±2.8 kgC/m 2 and 0.5±0.1 kgN/m 2 for the upper frozen layer. Organic carbon and total nitrogen stocks for the active soil layer and upper frozen layer in polygonal-fissure mires are evaluated as 172.0±29.1 ktC and 5.4±1.2 ktN.

The continuous measurement of CO2 fluxes at the open-top chamber experiment in the ombrotrophic peatland (located in the middle taiga zone, West Siberia, Russia) has been provided during the warm season of 2022 (beginning of June to beginning of October). The Reco, NEE and GPP were calculated for this period; abiotic factors related to CO2 emissions, such as PAR, air temperature, water table level and precipitation, were also measured. The monthly average values showed a negative NEE of -9.89 C g m-2 month-1 in July, a negative GPP of -34.19 C g m-2 month-1 in July, and a positive values Reco of 41.68 C g m-2 month-1 in August. In 2022, the studied peatland hollows were only a carbon stock in July, while in the remaining months they were a source of CO2, which could be caused by small precipitation amount. The monthly average diurnal variations of CO2 fluxes showed similar behaviour for both the OTC plot and control plot fluxes, which may be explained by the similarity in vegetation cover.

The peatlands of the West Siberian Lowlands, comprising the largest pristine peatland area of the world, have not previously been covered by continuous measurement and monitoring programs. The response of peatlands to climate change occurs over several decades. This paper summarizes the results of peatland carbon balance studies collected over ten years at the Mukhrino field station (Mukhrino FS, MFS) operating in the Middle Taiga Zone of Western Siberia. A multiscale approach was applied for the investigations of peatland carbon cycling. Carbon dioxide fluxes at the local scale studied using the chamber method showed net accumulation with rates from 110, to 57.8 gC m−2 at the Sphagnum hollow site. Net CO2 fluxes at the pine-dwarf shrubs-Sphagnum ridge varied from negative (−32.1 gC m−2 in 2019) to positive (13.4 gC m−2 in 2017). The cumulative May-August net ecosystem exchange (NEE) from eddy-covariance (EC) measurements at the ecosystem scale was −202 gC m−2 in 2015, due to the impact of photosynthesis of pine trees which was not registered by the chamber method. The net annual accumulation of carbon in the live part of mosses was estimated at 24–190 gC m−2 depending on the Sphagnum moss species. Long-term carbon accumulation rates obtained by radiocarbon analysis ranged from 28.5 to 57.2 gC m−2 yr−1, with local extremes of up to 176.2 gC m−2 yr−1. The obtained estimates of various carbon fluxes using EC and chamber methods, the accounting for Sphagnum growth and decomposition, and long-term peat accumulation provided information about the functioning of the peatland ecosystems at different spatial and temporal scales. Multiscale carbon flux monitoring reveals useful new information for forecasting the response of northern peatland carbon cycles to climatic changes.

Abstract. Dissolved organic carbon is an additional path of carbon cycle but there is a lack of information about its distribution in peatland and rates of downward movement. We dated seven peat cores (separately the dissolved (DOC) and particulate (POC) organic carbon) from Mukhrino peatland (typical zonal oligotrophic bog) in western Siberia to assess the date distribution between those two peat fractions. Our results revealed that the DOC is younger than POC for the surface peatland layers (0–150 cm) and older for the deeper layers. The date differences increases with depth and reaches 2000–3000 years at the bottom layer (430–530 cm). In our hypothesis this date discrepancy caused by more young DOC moving to the deeper and older peat layers. The estimated average value of DOC downward movement was 0.047 ± 0.019 cm yr−1. Th oldest dates found at the lake bottom and ancient riverbed were 10 053 and 10 989 cal yr BP correspondingly. For the whole period of peatland functioning the average peat accumulation rate was estimated as 0.067 ± 0.018 cm yr−1 (0.013–0.332 cm yr−1), the carbon accumulation rate was estimated as 38.56 ± 12.21 g С m−2 yr−1 (28.46–57.91 g С m−2 yr−1).

To analyze the pattern of ecosystems on the territory of the Central Tuvinian Basin the images from the Landsat-8 satellite for the summer period of 2020 were used. Satellite images were processed in the GRASS geographic information system using the SMAP classification method. The basin under study is located in the center of the Republic of Tuva. The region is characterized by a sharply continental climate with low snowy and very cold winters, hot and dry summers. Based on satellite information and the cartographic information, 13 land units were identified in the studied territory of the Central Tuvinian Basin. The total area of the Central Tuvinian Basin is 18.6 thousand km2 . A mosaic ecosystem structure of typical, dry and desert steppes is presented on the flat territory of the basin. Based on the satellite images, a map-scheme for ecosystems pattern on the territory of the Central Tuvinian Basin was made. Steppe vegetation is gradually occupying the abandoned arable lands. The area of cultivated fields in the Central Tuvinian Basin has decreased by 90% over the past 30 years. There was an expansion of the territories of dry and desert steppes with the participation of shrubs of Caragana Bunge. Desertification processes are ongoing in the Central Tuvinian Basin.

Arctic sea-ice loss is emblematic of an amplified Arctic water cycle and has critical feedback implications for global climate. Stable isotopes (δ 18 O, δ 2 H, d-excess ) are valuable tracers for constraining water cycle and climate processes through space and time. Yet, the paucity of well-resolved Arctic isotope data preclude an empirically derived understanding of the hydrologic changes occurring today, in the deep (geologic) past, and in the future. To address this knowledge gap, the Pan-Arctic Precipitation Isotope Network (PAPIN) was established in 2018 to coordinate precipitation sampling at 19 stations across key tundra, subarctic, maritime, and continental climate zones. Here, we present a first assessment of rainfall samples collected in summer 2018 ( n = 281) and combine new isotope and meteorological data with sea ice observations, reanalysis data, and model simulations. Data collectively establish a summer Arctic Meteoric Water Line where δ 2 H = 7.6⋅δ 18 O–1.8 ( r 2 = 0.96, p < 0.01). Mean amount-weighted δ 18 O, δ 2 H, and d-excess values were −12.3, −93.5, and 4.9‰, respectively, with the lowest summer mean δ 18 O value observed in northwest Greenland (−19.9‰) and the highest in Iceland (−7.3‰). Southern Alaska recorded the lowest mean d-excess (−8.2%) and northern Russia the highest (9.9‰). We identify a range of δ 18 O-temperature coefficients from 0.31‰/°C (Alaska) to 0.93‰/°C (Russia). The steepest regression slopes (>0.75‰/°C) were observed at continental sites, while statistically significant temperature relations were generally absent at coastal stations. Model outputs indicate that 68% of the summer precipitating air masses were transported into the Arctic from mid-latitudes and were characterized by relatively high δ 18 O values. Yet 32% of precipitation events, characterized by lower δ 18 O and high d-excess values, derived from northerly air masses transported from the Arctic Ocean and/or its marginal seas, highlighting key emergent oceanic moisture sources as sea ice cover declines. Resolving these processes across broader spatial-temporal scales is an ongoing research priority, and will be key to quantifying the past, present, and future feedbacks of an amplified Arctic water cycle on the global climate system.

The response of peatlands to climate change can be highly variable. Through understanding past changes we can better predict the response of peatlands to future climate change. We use a multi-proxy approach to reconstruct the surface wetness and carbon accumulation of the Mukhrino mire (Western Siberia), describing the development of the mire since peat formation in the early Holocene, around 9360 cal. year BP. The mire started as a rich fen which initiated after paludification of a spruce forest (probably in response to a wetter climate), while the Mukhrino mire progressed to ombrotrophic bog conditions (8760 cal. year BP). This transition coincided with the intensive development of mires in Western Siberia and was associated with active carbon accumulation (31 g m −2 year −1 ). The ecosystem underwent a change to a tree-covered state around 5860 cal. year BP, likely in response to warming and possible droughts and this accompanied low carbon accumulation (12 g m 2 year −1 ). If the future climate will be warmer and wetter, then regional mires are likely to remain a carbon sink, alternatively, a reversion to the wooded state with reduced carbon sink strength is possible.

The landscape diversity of the tundra area in the Pur–Taz interfluvial region are analyzed using field and remote sensing data. For each land unit (microlandscape), botanical, microrelief, and soil descriptions are produced, projective covers of plant species are estimated, and seasonal soil thawing depths are defined. Additionally, the water table levels, pH, and electrical conductivity (EC) of peatland waters are measured in waterlogged microlandscapes.