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Fires are predicted to increase in Arctic regions due to ongoing climate change. Tundra fires can alter carbon and nutrient cycling and release a substantial quantity of greenhouse gases with global consequences. Yet, the long-term effects of tundra fires on carbon (C) and nitrogen (N) stocks and cycling are still unclear. Here we used a space-for-time approach to investigate the long-term fire effects on C and N stocks and cycling in soil and aboveground living biomass. We collected data from three large fire scars (>44, 28, and 12 years old) and corresponding control areas and used linear mixed-effect models in a Bayesian framework to analyse long-term development of C and N stocks and cycling after fire. We found that tundra fires had no long-term effect on total C and N stocks because a major part of the stocks was located belowground in soils which were largely unaltered by fire. However, fire had a strong long-term effect on stocks in the aboveground vegetation, mainly due to the reduction in the lichen layer. Fire reduced N concentrations in graminoids and herbs on the younger fire scars, which affected respective C/N ratios and may indicate an increased post-fire competition between vascular plants. Aboveground plant biomass was depleted in 13C in all three fire scars. In soil, the relative abundance of 13C changed with time after fire. Our results indicate that in lichen-rich subarctic tundra ecosystems, the contribution of fires to the release of additional carbon to the atmosphere might be relatively small as soil stocks appear to be resilient within the observed time frame.

Agro-development of northern territories results in radical transformation of soils of these ecosystems. On the example of Nadym district (N 65.5; E 72.6) of Yamal-Nenets Autonomous Okrug (Russia) it is shown that the process of agrogenic transformation of reference podzols is similar to the process of formation of Plaggen soils, which were repeatedly found in Northern Europe and other regions (Plaggen Anthrosols – result of Plaggen Management). As a result of the application of large amounts of organic substrate (Plaggen Material), the thickness of the surface horizons increases considerably (from 3 cm to more than 30 cm in some cases). These soils occupy an intermediate position from reference soils to highly transformed − Hortic/Plaggic Podzols. Hortic and Plaggic horizons are characterized by reduced acidity (pH H2O 5–6, pH CaCl2 4–5), increased content and stock of organic carbon (5.4–14.5 %). Soils of agrogenic and postagrogenic ecosystems are characterized by relatively high content of basic nutrients (P-P2O5 up to 386 mg kg−1, K-K2O up to 239.0 mg kg−1) and clay (up to 20.9 %), also the degree of their microstructure increases in comparison with reference Podzols of Nadym district. The taxonomic composition of soil microbiome also changes greatly in the process of agricultural development of soils. In reference Podzols Proteobacteria, Actinobacteria and Bacteroidetes dominate. In general the microbiological profile in the of agrogenic and postagrogenic soils shifts towards the increase of the phyla Proteobacteria, Acidobacteria, Planctomycetes, Nitrospirae, Verrucomicrobia (for abandoned lands) and Actinobacteria, Bacteroides, Firmicutes, Euryarchaeota (for soil in use).

Permafrost-affected regions in the Russian Arctic are a critical study area for studying the sources of metal elements (MEs) in soils originating from geological/pedogenic processes or from anthropogenic sources via atmospheric transport. In the Nadym region of the Yamalo-Nenets Autonomous District, we investigated the contents of soil organic carbon (SOC), total nitrogen (TN), and MEs across different soil types and horizons, explored the source apportionment of MEs, and assessed local ecological risks of potentially toxic elements (PTEs). The results showed that (1) the contents of SOC and TN in Histic Cryosols (8.59% and 0.27%) were significantly higher than in Plaggic Podzols (Arenic, Gelic, and Turbic) (2.28% and 0.15%) and in Ekranic Technosols (Umbric) (1.32% and 0.09%); (2) the concentrations of MEs in the Nadym region were lower than in other Arctic regions; (3) the primary sources of MEs were identified as geological processes (36%), atmospheric transport (23%), agricultural activities (21%), and transportation (20%); and (4) the permafrost-affected soils in the Nadym region exhibited low ecological risks from PTEs. These results underscore the critical role of geological and anthropogenic factors in shaping soil conditions and highlight the relatively low ecological risk from PTEs, providing a valuable benchmark for future environmental assessments and policy development in Yamal permafrost regions.

Over the past few decades, climate warming has driven alterations in both the discharge volume and biogeochemical composition of Arctic riverine fluxes. This study investigated the content of macro- and microelements in the lower reaches of the Ob River (western Siberia). Seasonal sampling was performed over a four-year period (2020–2023) during the main hydrological seasons (winter low water, spring-summer floods, and early fall low water) at three river stations. The results revealed significant seasonal variations in the elemental content of the Ob River water associated with changes in catchment inputs, physical and chemical conditions of the aquatic environment, and the amount and composition of incoming suspended sediment. During high water flow events in the Ob River, the concentration of suspended solids increased substantially. During the winter period when the Ob River was ice-covered, a two- to three-fold rise was observed in the concentration of Na, Mg, Ca, K, Si, and Mn. Having accounted for these seasonal variations in water chemistry, we were able to refine our estimates of elemental export to the Arctic Ocean. Compared to estimates from previous studies, we observed 2.3-fold higher dissolved loads of Mn, and the dissolved loads were higher by 2.1-fold for Zn, 1.6-fold for Fe, and 1.4-fold for Pb. The observed rise in elemental export is likely attributable to a confluence of factors, including permafrost thaw, enhanced water inflow from wetland catchments, and intensifying snowfall leading to increased flood runoff.

Permafrost-affected regions in the Russian Arctic are a critical study area for studying the sources of metal elements (MEs) in soils originating from geological/pedogenic processes or from anthropogenic sources via atmospheric transport. In the Nadym region of the Yamalo-Nenets Autonomous District, we investigated the contents of soil organic carbon (SOC), total nitrogen (TN), and MEs across different soil types and horizons, explored the source apportionment of MEs, and assessed local ecological risks of potentially toxic elements (PTEs). The results showed that (1) the contents of SOC and TN in Histic Cryosols (8.59% and 0.27%) were significantly higher than in Plaggic Podzols (Arenic, Gelic, and Turbic) (2.28% and 0.15%) and in Ekranic Technosols (Umbric) (1.32% and 0.09%); (2) the concentrations of MEs in the Nadym region were lower than in other Arctic regions; (3) the primary sources of MEs were identified as geological processes (36%), atmospheric transport (23%), agricultural activities (21%), and transportation (20%); and (4) the permafrost-affected soils in the Nadym region exhibited low ecological risks from PTEs. These results underscore the critical role of geological and anthropogenic factors in shaping soil conditions and highlight the relatively low ecological risk from PTEs, providing a valuable benchmark for future environmental assessments and policy development in Yamal permafrost regions. [ABSTRACT FROM AUTHOR]

Over the past few decades, climate warming has driven alterations in both the discharge volume and biogeochemical composition of Arctic riverine fluxes. This study investigated the content of macro- and microelements in the lower reaches of the Ob River (western Siberia). Seasonal sampling was performed over a four-year period (2020–2023) during the main hydrological seasons (winter low water, spring-summer floods, and early fall low water) at three river stations. The results revealed significant seasonal variations in the elemental content of the Ob River water associated with changes in catchment inputs, physical and chemical conditions of the aquatic environment, and the amount and composition of incoming suspended sediment. During high water flow events in the Ob River, the concentration of suspended solids increased substantially. During the winter period when the Ob River was ice-covered, a two- to three-fold rise was observed in the concentration of Na, Mg, Ca, K, Si, and Mn. Having accounted for these seasonal variations in water chemistry, we were able to refine our estimates of elemental export to the Arctic Ocean. Compared to estimates from previous studies, we observed 2.3-fold higher dissolved loads of Mn, and the dissolved loads were higher by 2.1-fold for Zn, 1.6-fold for Fe, and 1.4-fold for Pb. The observed rise in elemental export is likely attributable to a confluence of factors, including permafrost thaw, enhanced water inflow from wetland catchments, and intensifying snowfall leading to increased flood runoff. [ABSTRACT FROM AUTHOR]

The post-anthropogenic and soil cover transformations of former agricultural soils on the abandoned lands in the Russian Arctic territory are poorly investigated due to the active growth of the city complexes and increasing area occupied by agricultural lands. That is lead to an increase in the area of the arable lands surrounding the polar urbanized territories. Today, most of that land allocated for agricultural needs has been abandoned or affected by other types of land use. This study aimed to investigate the abandoned lands surrounding some of the settlements in the central part of the Yamal region. The soil diversity, morphology, and chemical and agrochemical properties were investigated with special reference to the specific transformations that occur to fallow lands under permafrost-affected cryogenic-ecosystem conditions. Analysis of data show that these soils are characterized by features relating to both, previous (and existing), anthropogenic impacts and natural processes such as cryogenic mass transfer. The degradation of the arable humus-enriched horizon was not as pronounced as it has been in more humid boreal environments over recent decades. The organic carbon content in topsoil depends on the land use and varied considerably among the soil types. The former arable topsoil horizon has been stable over time in terms of its morphological features and agrochemical state. Despite the high soil acidity levels, thenutrient content in the anthropogenically impacted soils was still high, even though being abandoned for 20 years.

Ongoing climatic changes are influencing the volume and composition of the river waters that enter the Arctic Basin. This hydrochemical study was conducted within the mouth of the Ob River, which is one of the world’s largest rivers, providing 15% of the Arctic Ocean’s total intake. Concentrations of suspended and dissolved elements were determined using ICP–MS and ICP–AES. As compared to the world average values, the Ob river water had higher concentrations of dissolved P, As, Cu, Zn, Pb and Sb, i.e., the elements that form soluble organo-mineral complexes. The composition of suspended matter was characterized by low concentrations of most trace elements (Cd, Cr, Co, Cu, Mo, Al, Ni, Pb, V) due to their low contents in peat soils within the river drainage basin. Concentrations of dissolved forms were many times lower than concentrations of suspended forms in Al, Fe, Mn, Zn, Cr, Co, Ti, Sc, and all rare earth elements. Total concentrations of Ni, Cu, Bi, Pb, W in the river water increased by 2.5 to 4.2 times during the summer. The effects of climate change, which can cause an increase in the discharge of solid particles from thawing permafrost, are likely to lead to an increase in the discharge of certain elements into the Ob River estuary.

Active land disturbance of soil and environments appears even in remote landscapes of tundra and forest tundra. Wildfires become a frequent factor of soil degradation and intensification of permafrost degradation, also affecting the global balance of carbon, especially content and distribution of polycyclic aromatic compounds. Mature unaffected by fire sandy-textured podzols soils were investigated in comparison with the same soil strongly affected by surface fire in the end of August 2016 in surroundings of the Pangody settlement, Nadym district, Yamal region. Data obtained showed an intensive morphological transformation of the topsoil layers, decreasing total organic matter and apparently increasing the humus enrichment by nitrogen. Wildfires also result in complete transformation of the fractional composition of the polycyclic aromatic compounds. The sum of PAHs increases intensively as well as benzo(a)pyrene content in soils. Therefore, soils of the cryolithozone become more faced to the wildfires during the last decades. Even one-time fire effect results in serious transformation of soil geochemical state.

Dynamically developing urbanization causes a number of environmental effects, including those related to the chemical transformation of soils. Relatively less information about the urban areas of the Arctic and Subarctic zones, constructed mostly on permafrost and intensively populated areas can be found. By the example of the analysis of basic soil properties and concentrations of trace metals in the soils of the cities of Salekhard, Urengoy, Nadym, Novy Urengoy and Gaz Sale (the Yamalo-Nenets Autonomous District), as well as various functional zones within the cities, the relationship between the age of the cities, the level of anthropogenic pressure and the type of parent materials and the character of accumulation of metals in the soil profile of urban soils have been described. The direct correlation was found between the content of Pb, Cr, Ni, As and soil sorption characteristics. In young cities built on sandy sediments, there is less accumulation of heavy metals in the topsoil horizons. Relatively higher concentrations of Cu and Cd were noted in soils of industrialized cities, regardless of functional zones. The higher content of Cr, Ni, Cu, Zn, As and Pb has been registered in older zones also frequently used for residential purposes. The calculated values of the PI index for some functional zones of young cities show the medium and high content of heavy metals. The analysis of Igeo and PLI indices shows a large diversity both in relation to individual cities and their functional zones. Soil quality, in spite of the high level of anthropogenic load, was assessed as mostly satisfactory.

Urban landscape combines built-up areas with strongly altered natural (green and blue) and other open spaces. Voluminous literature examines urban socio-environmental interactions in tropical and temperate cities, whereas high-latitude cities are rarely considered. Here, we create a historical perspective on urban green (vegetation) and blue (water) spaces in a sub-Arctic city of Nadym in Russia. Our study explores a novel way to combine quantitative information from satellite imagery and biometric studies with qualitative information from interviews with stakeholders and residents. Such a joint analysis helps to understand dynamics of the urban green and blue space as well as its value for society. Furthermore, we propose objective indicators reflecting societal values of spaces in connection with recreational and ecological services. By contrast to temperate city studies, we found that green space is less used in summer, but still highly valued, deep lakes are used and valued more than warmer shallow lakes, and winter white space do not shrink but enhance the urban public space. Satellite images reveal inevitable loss of green space to urban construction and its remediation by artificial plantings (almost by 30% at present), whereas less valued blue space decreased almost three-fold. Interviews reveal that shallow lakes have reduced recreational values due to ice bottom and algae bloom. High values are attributed to deep artificial lakes, which are more than ten times deeper than natural lakes and do not freeze throughout in winter. Our biometric studies show that trees in urban environment are significantly taller than in the corresponding undisturbed areas. Since majority of the Arctic cities are built using very similar planning ideas and technologies, our findings shall help objective appreciation of green and blue spaces in other settlements.

Fires are predicted to increase in Arctic regions due to ongoing climate change. Tundra fires can alter carbon and nutrient cycling and release a substantial amount of greenhouse gases with global consequences. Yet, the long-term effects of tundra fires on carbon (C) and nitrogen (N) stocks and cycling are still unclear. Here we used a space-for-time approach to investigate the long-term fire effects on C and N stocks and cycling in soil and aboveground living biomass. We collected data from three large fire scars (>44, 28 and 12 years old) and corresponding control areas and used linear mixed-effects models in a Bayesian framework to analyse how the stocks and cycling were influenced by fire. We found that tundra fires did not affect total C and N stocks because a major part of the stocks was located belowground in soils, which were largely unaltered by fire. However, fire had a strong effect on stocks in the aboveground vegetation, mainly due to the reduction of the lichen layer. Fire reduced N concentrations in graminoids and herbs on the younger fire scars, which affected respective C/N ratios and indicated an increased post-fire competition between vascular plants. Aboveground plant biomass was depleted in 13C in all three fire scars. This could be related to a lower 13C abundance in CO[sub 2] in the ambient air because of increased post-fire decomposition, providing a source of 13C-depleted CO[sub 2]. In soil, the relative abundance of 13C changed with time after fire because of the combined effects of microbial decomposition and plant-related fractionation processes. Our results indicate that in lichen-rich subarctic tundra ecosystems, the contribution of fires to the release of additional carbon to the atmosphere might be relatively small as soil stocks appear to be resilient. [ABSTRACT FROM AUTHOR]