Carbon-to-nitrogen Ratio and Variations of Stable Carbon Isotopes in Peat Overlying the Palsa Near the Eletsky Village

Vasil'chuk Alla Constantinovna Doctor of Geography Leading Research Fellow, Laboratory of Geoecology of the Northern Territories, Faculty of Geography, Lomonosov Moscow State University 119991, Russia, g. Moscow, Leninskie Gory, GSP-1, 1,, geograficheskii fakul'tet, NIL geoekologii Severa alla-vasilch@yandex.ru Other publications by this author     Vasil'chuk Yurii Kirillovich ORCID: 0000-0001-5847-5568 Doctor of Geology and Mineralogy Professor, Department of Landscape Geochemistry and Soil Geography, Lomonosov Moscow State University 119991, Russia, Moscow, Leninskie Gory str.,, 1, of. 2009 vasilch_geo@mail.ru Budantseva Nadine Arkad'evna ORCID: 0000-0003-4292-5709 PhD in Geography Senior Scientific Associate, Department of Landscape Geochemistry and Soil Geography, Faculty of Geography, Lomonosov Moscow State University 119991, Russia, Moscow, Leninskie Gory str., 1, office 2007 nadin.budanceva@mail.ru Other publications by this author     Bludushkina Lyubov' Bakhtiyarovna ORCID: 0000-0003-2422-8790 Engineer, Department of Landscape Geochemistry and Soil Geography, Faculty of Geography, Lomonosov Moscow State University 119991, Leninsky Gory, 1, office 2007, Moscow, Russia bludushkina19@mail.ru Vasil'chuk Jessica Yur'evna ORCID: 0000-0002-4855-8316 Junior Researcher, Department of Landscape Geochemistry and Soil Geography, Faculty of Geography, Lomonosov Moscow State University 119991, Leninskie Gory 1, office 2007, Moscow, Russia jessica.vasilchuk@gmail.com Other publications by this author     Ginzburg Alexander Pavlovich Bachelor, Department of Landscape Geochemistry and Soil Geography, Faculty of Geography, Lomonosov Moscow State University 119991, Russia, Moscow, Leninskie Gory, 1, office 2007 alexandrginzburg13154@yandex.ru

Slyshkina Elena Sergeevna Head of the Laboratory, JSC Atomenergoproekt 119234, Podol'skikh Kursantov str., 1, office 250, Moscow, Russia lena.slyshkina@gmail.com Other publications by this author

IntroductionAt present, the dynamics of bumpy peatlands is of increased interest to researchers because the heave mounds – the finger ? are a reliable indicator of changes in the state of permafrost peatlands.

Productivity of tundra landscapes is associated with changes in nitrogen and carbon content in peat during freezing?thawing. The peatlands of the Arctic and Subarctic are a huge reservoir of carbon, which is estimated at 415 ± 150 petagrams (1 gram is equal to 1 ? 10-15 petagrams) of carbon^[1]. In other studies, taking into account the edom thicknesses, the carbon reservoir in the Arctic is estimated even higher to 1055 petagrams^[2,3], which is 35-70% of all organic soil carbon ^[4]. The nitrogen content in peatlands is estimated at 10 ± 7 petagrams^[1]. Most of the carbon of high-latitude peatlands, according to some estimates it is 277-800 petagrams, is currently permafrost and does not undergo decomposition^[3]. The age of the peat cover of the finger is reliably determined by the radiocarbon method, which makes it possible to temporarily link geochemical and biochemical data. The degree of decomposition of peat in the process of degradation of permafrost rocks is estimated using isotopic analysis of peat carbon ^[5,6,7,8]. The analysis of the carbon and nitrogen content allows us to determine with a high degree of confidence the history of the development of the peat layer. The possibility of assessing the development of the Yeletsky palm massif based on data on the carbon and nitrogen content, as well as the isotopic composition of peat, is the task of this study.

Research area and samplingThe village of Yeletsky (67°02' s.w. and 64°12' v.d.) is located in the European part 

Polar?The Urals is 52 km south of Vorkuta. The region is located on the border of the stable Siberian anticyclone region and areas exposed to Atlantic warm cyclones. Therefore, the climate is unstable with heavy snowfalls, blizzards and severe frosts. The period of negative temperatures is from October to March. According to the data of the Yeletskaya weather station in the interval 1959-2022, the minimum average annual temperature was recorded in 1998 -8.3 °C; the average value of this indicator is -4.9 ° C, the maximum is -0.8 °C in 2020.  The lowest average daily temperature was observed in February 1966 ? 30 °C, and February 1998 -29.6 °C; the average daily January temperature was -19.7 °C, the average temperature of the three winter months -18.2 °C. The maximum average daily temperature of +18.3 °C was recorded in July 2007, the average July temperature was +13.7 °C, during the observation period there was no recorded average daily July temperature below +7.6 °C, which was observed in 1997, the average temperature of the three summer months was +10.5 °C. The maximum precipitation of 910 mm/year was observed in 1975, the minimum - 391 mm/year in 1985, the average value of this indicator - 607.4 mm/year ^[9].   Near the Palza massif there are p . The Usa and its tributary the Yelets River. According to the Federal State Budgetary Institution "Northern UGMS", the average annual water consumption of p.Usa - 1310 m3/s, the largest - 21500 m3/s (June), the smallest - 43.9 m3/s (April). The ice is frozen in October - the 1st half of November, it is opened in May-June. Snow and rain food. On p . According to the data of the Federal State Budgetary Institution "Northern UGMS", the intensity of water rises is from 40 to 120 cm, on the floodplain of the river.The period of high-water standstill lasts from mid-May to the first decade of June ^[10].
In the area of the Palza-Eletsky massif, zonal vegetation is practically not represented due to the lack of appropriate habitats. Communities of convex-hummocky and flat-hummocky peat bogs, grass-moss bogs representing intrazonal vegetation dominate. Larch woodlands with birch (Picea obovata, Betula tortuosa) are stunted, with a curtin undergrowth of Betula nana, with mosaic long-mossy-green-mossy and shrubby cover are found on the marginal parts of peat bogs^[11]. Palza-the Yeletsky massif was formed within the former lake basin. More than 20 fingers were found within the basin (Fig. 1). They are evenly distributed over the area of the basin, in terms of the finger more often have an oval shape, less often ? rounded, their dimensions are approximately from 1.5x2 to 10x12 m (Fig. 2). The highest hillock reaching a height of 6 m is located in the northwest of the basin. Remnants of shrubs, mainly Betula nana, were found on the tops of the hillocks, birch trees grow on the slopes of some palm trees, their height reaches 3-4 m. On the mounds, bagulnikovo-cloudberry-lichen communities predominate, in the interbug depressions, mainly sedge-sphagnum with ernik plant communities. The soil cover is represented by peat-cryozems and peat-gleezems

Fig. 1. Points of detailed work and sampling for nitrogen, carbon and radiocarbon analysis on the Yeletsky finger array: 2015 selection: El-15-7, El-15-5, El-15-6; 2018 selection: 18EL-VC; 2019 selection: E-VB-2019/47, E-VB-2019/48, 2020 selection El-20-1, El-20-2, El-20-3.

Fig. 2. The studied fingers near the village of Yeletsky, 2017  Photo by Yu.K. VasilchukMeasurement methods

The frozen core was selected using electric drills Makita DDF481rte 18B and Bosch GSR 36 VE-2-LI.

Peat samples were dried at a temperature of 50 ° C for 72 hours, then crushed to powder. In the Laboratory of Landscape Geochemistry of the Department of Landscape Geochemistry and Soil Geography of the Faculty of Geography of Lomonosov Moscow State University, measurements of the percentage of nitrogen and carbon in peat were performed. The measurements were carried out on a VARIO EL III V4.01 CHNS analyzer 20.Aug. 2002, Elementar Analysen systeme GmbH, Germany. Sulfanylic acid (Merck) was used as a standard with values of N = 8,090%, C = 41,610%.

The carbon isotope composition was determined in the isotope laboratory of the MSU Faculty of Geography using a Delta-V mass spectrometer with the standard element-analyzer option. The international standards IAEA-CH-3 (the value of ?13 C = -24.724%) and IAEA-CH-6 (the value of ?13 C = -10.449%) were used for measurements. The accuracy of the definitions of ?13 S was ± 0.2%.

Molar ratio C ^a/N ^a (C ^a and N ^a - the ratio of the percentage of carbon and nitrogen to atomic weight) calculated based on the results of the determination of carbon and nitrogen included in the organic matter. For soil horizons, the value of C ^a/N ^a equal to 8-10 corresponds to a high and average nitrogen supply of humus^[12]. Very high values of 18-20 or more are characteristic of horizons with a low nitrogen content, for example, coarse humus horizons of forest soils. For very humus-poor sediments, the value of C ^a/N ^a does not exceed 2-3 units.Results

Studies of the dynamics of the finger in the north-east of the Bolshezemelskaya tundra, including in the area of the village of Yeletskaya, have been conducted since 2000, to the present ^[7.8,13].

Within the convex-bumpy massif in the area of the village of Yeletsky (67°16's.w., 63°39' v.d.), heave mounds with a height of 1.5 to 5 m were studied in detail (Fig. 1). Samples were taken from sections located in various geomorphological positions: on the tops, slopes and at the foot of the palm, and also in the hollows on the tops of the hills.

Point El-15-5 ? the palm tree is about 1.5 m high, 2x2 m in size. The surface of the hillock is hummocky, dwarf birch, cloudberry, purple rose, mosses and lichens predominate in the plant composition. In the pit laid at the top of the hillock, it was opened:

0-0.16 m – brown loose peat, with remnants of twigs, roots, few decomposed plants;

0.16-0.4 m – peat is dark brown with layers of light brown, horizons of wetter and denser peat are distinguished, remnants of bark, twigs, wood fibers are found;

0.4-0.6 m – peat is brown and reddish-brown, with wood fibers, with remnants of bark and twigs. In the lower part of the layer, at the border of seasonal thawing, peat is denser and wetter. From a depth of 0.6 m, the peat is frozen;

Point El-15-6 - the palm tree is at the stage of degradation, with a crater in the central part, the height of the hillock is about 1.5 m, the excess of the marginal part above the crater is about 0.4 m. The central sagging part of the hillock is almost devoid of vegetation, on the slope of the hillock there is a depressed form of Betula tortuosa and several Betula nana bushes. Mainly grassy vegetation grew on the elevated part of the hillock. 2 pits were laid – in the center of the exposed peat in the crater (No. 1), and in the marginal part of the roller (No. 2). In the pit at the top of the hillock opened:

0-0.55 m - peat is dark brown, dry, loose, sometimes layered, with pieces of bark, with layers of wood residues and poorly decomposed plant residues. At a depth of 0.5 m, a 5-cm layer of poorly decomposed large wood residues was found. The peat was covered with gray loam;

In pit No. 2, the peat thickness was about 0.25 m, the peat is loose in the upper part, denser in the lower, interlayers of wood residues are noted. A gray loam, torn off, was uncovered under the peat.  

The hillock of heaving 3.5 m high Point EL20-1 in Fig. 1 (El-15-7) is one of the largest and most pronounced in the relief of the mounds in the study area. Its size is 5x6 m, several cracks can be traced on the slopes, there are small patches of bare peat on the top and slope of the hillock. The vegetation is dominated by dwarf birch, cloudberry, bagulnik, mosses and lichens. In the lower part of the slopes of the hillock, the proportion of dwarf birch in the vegetation increases, cereals and sedges are also found. 2 pits were laid – on the top (No. 1) and on the slope (No. 2). In the pit at the top of the hillock opened:

0.54 m – layering of peat brown, dark and light brown, with inclusions of wood residues (wood, bark), twigs, in the lower part of the layer the amount of wood residues increases;0.54-0.6 m – a layer of poorly decomposed wood, with inclusions of bark and twigs;

0.6-0.67 m – peat with wood residues, frozen, ice in the form of small inclusions;

In a pit on the slope of a hillock (on a bare patch of peat), it was opened:

0-0.16 m? peat is light brown and brown, loose, with inclusions of wood residues and twigs;

0.16-0.23 m – wood residues;

0.23-0.5 m – peat is brown and dark brown, fibrous, denser, with inclusions of twigs, bark. The density and humidity of peat increased with depth;

During the 2017 field season, a pit was laid at the top of this heaving hillock to the lower limit of seasonal thawing (0.75 m). A well with a depth of 0.8 m was drilled in the frozen peat and the underlying loam, with the selection of segregation ice for the analysis of ? ¹⁸ O and ? ² N.

Peat samples were taken from the peat layer covering the studied mounds with a detail of 3-5 cm to analyze the content of C, N, and determine the isotopic composition of carbon (?13 C). Peat from moistened depressions was also selected for this series of definitions.

Point EL20-1 is the top of a 3.5 m high hillock that was studied earlier,^[7] (EL-15-7). Selection of seasonally thawed peat - every 3 cm of peat was cut out of the pit wall with a knife, selection of frozen peat – from the well. In the pit at the top of the hillock opened:

0-5 cm – vegetable layer;

5-8 cm – roots of modern plants in peat;

8-11 cm – brown peat with rare modern roots;

11-14 cm – peat is brown, loose, dry, homogeneous;

14-17 cm – brown dense fibrous peat;

17-20 cm, peat is brown, dense, more moist;

20-23 cm – dense brown peat;

23-26 cm – peat dark brown, poorly laid layered;

26-29 cm – red interlayer of poorly decomposed wood in peat, loose peat;

29-32 cm – peat dark brown loose with remnants of bark and red wood;

32-35 cm – peat is dark brown dense, more moist;

35-38 cm – peat is dark brown in places, in places - just brown, with remnants of wood and undecayed plants;

38-41 cm – brown peat with patches of red. With the remains of undecayed plants;

41-44 cm – brown layered peat with undecayed wood;

44-47 cm – peat is dark brown dense with layers of light brown and wood residues;

47-50 cm – wood residues: branches, bark, loose;

50-53 cm – peat dark brown dense moist;

53-56 cm – dark brown peat with dense birch bark;

56-59 cm – peat dark brown dense moist;

59-61 cm – peat is dark brown dense in the lower part with wood residues;

61-63 cm – wood residues;

63-66 cm – reddish-brown loose peat drier with sediment residues;

66-69 cm – reddish-brown loose peat;

 69-72 cm – peat dryish loose reddish-brown;

72-75 cm – peat is brown at the bottom with spots of black, loose;

75-78 cm – peat dark brown, dense, moist;

81-84 cm – dark brown loose peat with pieces of bark;84-87 cm – dark brown loose peat with pieces of bark;

87-90 cm – dark brown loose peat with separate twigs;

90-93 cm – dark brown layered peat with twigs;

93-96 cm, black-brown wet peat;

96-99 cm – black-brown wet peat on the border with frozen, ice crystals in the lower part;

96-100 cm – black-brown frozen peat for dating ¹⁴ C.

Samples of frozen peat with segregation ice from the well (100-120 cm).Point EL20-2 (67,039083 s.w., 64,250277 v.d.) is the top of the heaving hill investigated in 2015.

(point EL-15-4). The heaving hillock is 3.5 m high. The maximum depth of thawing at the top of the hillock (at the end of September) was 0.65 m. 4 pits were laid from the top to the interbug depression. At the top of the hillock, a well was drilled from the bottom of the pit in frozen peat and underlying loam, 1.3 m deep. In the pit, laid on top of the hillock, are opened:

0-0.06 m – roots of modern plants;

0.06-0.54 m – peat is brown, with layers of light brown and black, with the remains of poorly decomposed vascular plants, with woody residues (wood fibers, bark), twigs. Peat is predominantly dense, fibrous;

0.54-0.65 m – peat is dark brown, dense, moist, on the border with frozen peat;

The well has been opened:0.65-1.25 m – frozen peat, cryotexture is thinly layered and massive.

1.25-1.7 m – gray, frozen loam, lenticular-layered cryotexture;

1.7-1.9 m – gray loam, frozen, very icy, cryotexture schlirovaya;

In the pit on the slope of the hillock opened:

0.05–0.3 m – brown peat, with wood fibers, a fragment of poorly decomposed red wood was found at a height of 0.25 m;

0.3-0.4 m – peat with a large number of interlayers of woody and grassy residues

0.4-0.6 m – the peat is fibrous, drier, at the base of the layer there is a large amount of poorly decomposed wood residues, the same as in the pit at the top of the hillock. 

Samples of peat deposits with an interval of 3-4 cm were taken to determine ? ¹³ C. In the pits on the top and slope of the hillock, as well as at the foot of the hillock in the inter-hill depression, peat samples were selected for ¹⁴ C dating. Segregation ice was selected from frozen peat and underlying loam for the analysis of ? ¹⁸ O and ? ² N.

Point EL20-6 (67,039634 S.S., 64,255261 V.D.)

A hillock of heaving about 5 m high with a wall of collapsed peat at the edge of the lake. In the outcrop revealed: 0-2.5 m – brown peat, layered, dry, the lower part of the peat (2.3-2.5 m) with a significant admixture of loam

2.5-3.5 m (lower open border) – gray loam with ice lenses (Fig. 3), the cryotexture is layered and layered-mesh, the thickness of the slots is from 1 to 4 cm. 

Fig. 3. With a gray coal with ice lenses in the core of the finger Yeletskaya, 2020, point EL20-6. Photo by J.Y. Vasilchuk

 Fig. 4. Schlier ice from the core in palza Yeletskaya, 2020, point EL20-6. Photo by Yu.K.VasilchukThe value of ?13 S in the peat 3.2 m finger ? point EL VB-19 varies within 3.55%, from -28.5 to -32.05%, averaging -30.33% (Table 1). The most negative values of ?13 S are traced in the range 0.52-0.69 m.

According to previous studies ^[8], the values of ?13 C in the range from -27 to -29.8 %, on average -28 %, were obtained in the peat of this finger. As a result of repeated study of the isotopic composition of peat, slightly lighter values were obtained, which is due to the heterogeneity of the botanical composition of peat.  In general, the composition of stable carbon isotopes shows slight lateral and radial variations. The C/N ratio in peat at the top of the heaving mound in the bulk of peat is about 15, rising to 30 in the lower part of peat and up to 40 in the surface ^[8]. The roots of modern plants cannot be traced from a depth of 10 cm, at this depth a local minimum of ?13 values With -30.87% is marked, obviously this peat layer corresponds to the mesothelm boundary layer between the acrotelm and the catothelm (between the layer formed by living plants and already dead plant remains).^{Table 1}

Values of ?13 S in peat, Yeletskaya, 2019 Point EL VB-19

The value of ?13 S in the peat of 3.5 m finger ? point EL 20-1- varies within 3.55 %, on average is -28.71% (Table. 2), wood of a high degree of decomposition corresponds to a value of ?13 with -29.02%. According to previous studies^[8], the values of ?13 C in the range from -27.64 to -29.06 % were obtained in the peat of this finger, with an average of -28.32 %. Variations in the content of stable carbon isotopes are insignificant. As a result of repeated study, very close values of the isotopic composition of peat were obtained.

The value of ?13 S in the 3.0 m peat of the finger ? point EL 20-2 - varies within 2.23 % from -29.48% to 27.25%, on average -28.05% (Table. 2), wood of a high degree of decomposition corresponds to a value of ?13 with -28.7%. The boundary layer of the mesothelm – between the acrotelm and the catothelm, according to isotopy data, is not traced, visually marked at a depth of 0.11 m, below the roots of modern plants are found only once. There are no differences in the isotopic composition of peat during the transition from thawed peat to frozen peat. The degree of decomposition of peat on the isotopic composition of peat is not traceable.

Table 2Values of ?13 S in peat, Yeletskaya, 2020 Points EL-20-1 (EL -15-7), EL -20-2 (EL -15-4), EL-20-3, EL-20-4

Table 3Carbon content, nitrogen, isotopic composition of carbon in peat 18el?VC

In the surface layer of the 18El?VC finger (Fig. 3), located on the periphery of the drained lake basin, the values of ?13 C vary narrowly from -27.77 to -29.50, the average value of ?13 C is -28.61 (Table 3).

Fig. 5. A thick layer of peat in the upper part of the 18El-VC finger. Photo by Yu.K. Vasilchuk

In peat, the maximum value of ?13 With -27.77% corresponds to a local minimum of nitrogen content of 2.09% and a local maximum of carbon content of 52.03%, as well as a maximum value of C/N of 31.12, possibly peat from this interval corresponds to the mesothelm – the boundary layer between acrotelm and catothelm, since below this layer the roots of modern vegetation during field the studies practically did not meet. At this level, the absolute peak of the values of the C/N ratio is 31.12. The nitrogen content is in the range of 1.777-4.475%, the average value is 3.309%. The carbon content is 29.48-55.36%, the average carbon content is 48.43%, while the minimum value falls on the peat layer bordering the underlying loam. The transition from thawed peat to frozen peat at a depth of 0.4 m is not marked by changes in the studied indicators. In the loam underlying peat, the carbon and nitrogen content is reduced, the C/N index is close to one. The degree of decomposition of peat did not affect the isotopic composition of peat and the nitrogen and carbon content.

DiscussionComparing the nitrogen and carbon content in litalza^[14] and palza^[7,8], we note that the range of nitrogen content fluctuations is significantly higher in litalza in the Sentsa River valley – from 0.45 to 8.86%, while in peat in the palza-Yeletsky massif from 0.23 to 4.48%, and carbon, on the contrary, is much higher from 29.48 to 60.47%, in the surface layers of lithals even with inclusions of buried peat from 2.52 to 11.56% (Table 4).

This evidently indicates the active processing of nitrogen by microorganisms and plants in the conditions of frost.

Table 4Carbon and nitrogen content and C a/N A values in the upper layer of the finger and litalz

Table 5Carbon and nitrogen content and C a/N a values in polygonal peatlands

Comparing the isotopic composition and carbon and nitrogen content in the Yeletsky palm massif with polygonal tundra peat bogs, in Central Yamal and Chukotka (Table. 5), we note that the average isotopic composition of carbon in polygonal peatlands is approximately the same, despite their distance from each other, which is explained primarily by the close composition of plant associations forming polygonal peatlands. If new ecological niches are formed during the formation and growth of the palm, and some phytocenoses are replaced by others, then in the case of polygonal peat bogs, no new ecological niches are created. Therefore, their isotopic composition is more or less homogeneous. Since polygonal peatlands develop in harsher conditions of both summer and winter seasons, the content of free nitrogen available to plants is even less than in bumpy peatlands. This is reflected in the high C/N values, the average values are 27.94-30.85. Due to the high degree of watering of the Yeletsky palm massif as a whole, mainly anaerobic conditions of peat destruction prevailed in the process of peat accumulation.

Peatlands that overlap the palm are unique habitats, because they have a lot of carbon, but they are thermodynamically passive. Abrupt climatic changes, such as, for example, flooding or the transition to a permafrost state, can change the rate of decomposition of organic matter. The degree of decomposition of peat is one of the basic characteristics of peat bogs, for which the conditions of waterlogging and/ or the existence of permafrost play a decisive role. In the flood zone, peat destruction is usually slowed down due to low oxygen content, in frozen peat bogs, destruction is suspended, in the aeration zone, peat decomposition rates are quite high^[17]. In one of the recent articles by R. Wilson^[18], it was found that the arrival of new organic matter from plants settled on thawing peat bogs significantly accelerates the decomposition of organic matter in the peat covering the finger. It was found that the mechanism of decomposition of organic matter was characterized by significant differences from other habitats where growing plants were absent, while no differences were noted in the flooded areas. This is confirmed by other studies, in which the main role in accelerating the destruction of peat is assigned to an increase in the number of root hairs in tundra plants growing on a peat substrate with an increase in summer temperature. It has also been established that even very short-term changes in temperature and humidity conditions affect the cumulative mineralization of carbon and nitrogen through minor changes in the concentrations of labile carbon and nitrogen in the acrotelma of peat bogs^[19]. With an increase in the depth of thawing of permafrost peatlands, plants with a more developed root system gain a competitive advantage^[20], this was established by the results of C/N determinations in the Stordalen ombrotrophic peat bog in northern Sweden to simulate the reaction of Arctic vegetation to nitrogen dynamics in an ecosystem with permafrost rocks using the JULES Land Surface model. Sphagnum fuscum is one of the main types of sphagnum moss, marking the beginning of the heave of the finger^[21]. Studies of the carbon isotope composition of cellulose stems from peat formed by Sphagnum fuscum on the surface of the finger have demonstrated a good correlation with July temperatures. The lowest values of ?13 C correspond to low values of the average air temperature^[22]. When comparing the data of the drained and watered parts of the peatland X .Nykanen and co-authors ^[23] showed that an additional factor that determines the values of ?13 C is the close occurrence of groundwater to the surface of the peat bog. In comparison with low-lying bogs, groundwater on top peatlands is located much deeper. Therefore , vascular plants on top peatlands are usually depleted of the ¹³ C isotope . If the process of photosynthesis of sphagnum occurs in humid conditions, the values of ?13 C of the plant increase, if in dry conditions they decrease. Aerobic microbiological decomposition increases the value of ?13 C of the remaining peat, while anaerobic decomposition of organic matter preserves or slightly reduces the values of ?13 C in peat. In a later article X .Nykanen and co-authors^[24] demonstrated that the profile of ?13 C of a single column can reflect the effects preserved as a result of moisture fluctuations. In the upper 50 cm of both moistened and drained peat bogs, no significant correlation was observed between the measured values of ?13 C and the carbon content (C%). A noticeable negative correlation between ?13 C and the sampling depth was found only in the profile of the drained peat bog. In both the drained and moistened parts of the peat bog, the lowest values of ?13 C were observed at the same depth, where they were also observed: the maxima of C%, N% and the minimum of the C/N ratio. According to the authors' conclusions, this fact reflected the presence of a peat bog development stage in warm and humid conditions. Although we note that the dynamics of heaving mounds is not always determined by the influence of climatic conditions. As a result of excessive accumulation of snow along linear structures, such as railways and trunk pipelines, degradation of hummocky massifs occurs. And, on the contrary, under favorable conditions, the origin and modern growth of heave mounds occurs, for example, in the valley of the Adyr?Khem River on the Alash plateau in the northwest of Sayan ^[25] at latitude 51 °. In general, boreal peatlands, despite the huge carbon reserves, are poor in nutrients and therefore are characterized by a higher carbon-to-nitrogen ratio (C/N) than peatlands of low latitudes, since carbon accumulates in the ecosystem, while nitrogen can circulate and be used by both microorganisms and vegetation^[26]. A pattern has been traced, in some cases the C/N values decrease with an increase in the degree of decomposition of peat^[27]. Aerobic decomposition of peat leads to enrichment of ¹³ C and ¹⁵ N of the remaining organic material. The content of stable carbon and nitrogen isotopes, according to the authors, reflects both the hydrological processes during the decomposition of peat and the isotopic composition of the initial plant material. For example, sedges are enriched with 13 C and ¹⁵ N, compared with shrub leaves, and sphagnum stems are characterized by a range of values of ?13 C from -25.0 and -29.6 %^[27]. The study of the impact of the drainage of the palm in the Stordalen swamp (68°21'20" s. w., 19°02'84" v. d.), in northern Sweden, with the determination of the C/N ratio, and variations of the values of ?13 C is devoted to the work of F. Klaus ^[28]. Three main habitats are considered within the palza massif: palza, palza partially thawed and inter?mountain thawed depressions. The highest value of C/N is noted in the upper 10 cm of the finger profile, the maximum value is 112.1. A decrease in C/N values in the upper 15 cm was found from more than 80 to less than 40 at a depth of 15 cm. At a depth of less than 15 cm, the C/N ratio in natural peatlands ranged from 26.7 to 57.2. The C/N ratio in the drained peatlands ranged from 20.5 to 78.4, and at both sites in the Trollberget values decreased in the upper 10 cm. The open forest area in Helsingfors Stormiran showed a more uniform C:N ratio with depth, varying from 46.7 to 71.6 across the entire profile. There was no significant difference in the C/N ratio on natural and drained peatlands when considering the entire peat layer. Isotopic recording in organic matter with depth showed slightly increasing values of ?13 C with depth for both drained and natural peatlands. The values of ?13 C ranged from -30.2 to -24.5, with the lowest values of ?13 C in the upper 10 cm of the peat profile. The highest value was measured at a depth of 39 cm in Helsingfors Stormiran^[28]. The study of the peat cover of the palm in Degero Stormyr^[29] in northern Sweden has an average C/N ratio of 57. A lower C/N ratio in the acrotelma ?a layer containing living plants ? (on average 41) and mesothelma – a transitional layer (on average 35) indicates higher mineralization rates with gaseous release of carbon and nitrogen. In the catothelm ? a layer containing dead plant material ? with natural anaerobic conditions, the C/N ratio was in the same range as in the acrotelm (on average 49). The C/N ratio in the sections of the peat of the overlapping finger is in Kevo (Lapland, northern Finland) 22.29 in drained peatlands and 26.88 in wet peatlands, in Karlbotn (Finmark, northern Norway) 22.741 in drained peatlands and 19.34 in wet peatlands^[30]. Detailed studies of A.Pastukhova and D.Kaverina with coauthors^[6] of variations in the values of ?13 C and C/N in sections of the peat of the overlapping palza in the southern part of the palza range at points Inta 1, Inta 2 and Colva showed that the values of ?13 C vary from -25 to -28 (to VPDB). Microbiological activity in the upper 20 cm of peat covering peat bogs was recorded with the highest values of C/N, 30-35, which indicates a low nitrogen content. In the lower layers of overlapping peatlands, the C/N ratio is significantly lower than 20-27 ^[30].

ConclusionStudies of the Yeletsky palm massif have shown that the isotopic composition of carbon in the Yeletsky palm massif is determined primarily by the botanical composition of plant residues.

There are no differences in the isotopic composition of peat during the transition from thawed peat to frozen peat. The degree of decomposition of peat on the isotopic composition of peat is not traceable. In comparison with litalza, nitrogen available to microorganisms and plants is processed much more actively in the conditions of palza. Since in the studied palm peat, the maximum value of ?13 With -27.77% corresponds to a local minimum of nitrogen content of 2.09% and a local maximum of carbon content of 52.03%, as well as a maximum value of C/N of 31.12, it is very likely that peat from this interval corresponds to the mesothelm – the boundary layer between the acrotelm and the catothelm, the results indicate a high degree of watering of the Yeletsky massif as a whole during the accumulation of peat and mainly anaerobic conditions of its decomposition.