Permafrost Research Articles

Links between seasonal suprapermafrost groundwater, the hydrothermal change of the active layer, and river runoff in alpine permafrost watersheds

Abstract. The seasonal dynamic of the suprapermafrost groundwater significantly affects the runoff generation and confluence in permafrost basins and is a leading issue that must urgently be addressed in hydrological research in cold and alpine regions. In this study, the seasonal dynamic process of the suprapermafrost groundwater level (SGL), vertical gradient changes of soil temperature (ST), moisture content in the active layer (AL), and river level changes were analyzed at four permafrost watersheds in the Qinghai–Tibet Plateau using comparative analysis and the nonlinear correlation evaluation method. The impact of freeze–thaw processes on seasonal SGL and the links between SGL and surface runoff were also investigated. The SGL process in a hydrological year can be divided into four periods: (A) a rapid falling period (October to mid-November), (B) a stable low-water period (late November to May), (C) a rapid rising period (approximately June), and (D) a stable high-water period (July to September), which synchronously respond to seasonal variations in soil moisture and temperature in the AL. The characteristics and causes of SGL changes significantly varied during these four periods. The freeze–thaw process of the AL regulated SGL and surface runoff in permafrost watersheds. During period A, with rapid AL freezing, the ST had a dominant impact on the SGL. In period B, the AL was entirely frozen due to the stably low ST, while the SGL dropped to the lowest level with small changes. During period C, ST in the deep soil layers of AL (below 50 cm depth) significantly impacted the SGL (nonlinear correlation coefficient R2 > 0.74, P < 0.05), whereas the SGL change in the shallow soil layer (0–50 cm depth) showed a closer association with soil moisture content. Rainfall was the major cause for the stable high SGL during period D. In addition, the SGLs in periods C and D were closely linked to the retreat and flood processes of river runoff. The SGL contributed approximately 57.0 %–65.8 % of the river runoff changes in the period D. These findings will help to facilitate future hydrological research in the permafrost basins and the development and utilization of water resources in cold and alpine regions.

Carbon Fate, Iron Dissolution, and Molecular Characterization of Dissolved Organic Matter in Thawed Yedoma Permafrost under Varying Redox Conditions.

Permafrost soils store ∼50% of terrestrial C, with Yedoma permafrost containing ∼25% of the total C. Permafrost is undergoing degradation due to thawing, with potentially hazardous effects on landscape stability and water resources. Complicating ongoing efforts to project the ultimate fate of deep permafrost C is the poorly constrained role of the redox environment, Fe-minerals, and its redox-active phases, which may modulate organic C-abundance, composition, and reactivity through complexation and catalytic processes. We characterized C fate, Fe fractions, and dissolved organic matter (DOM) isolates from permafrost-thaw under varying redox conditions. Under anoxic incubation conditions, 33% of the initial C was lost as gaseous species within 21 days, while under oxic conditions, 58% of C was lost. Under anoxic incubation, 42% of the total initial C was preserved in a dissolved fraction. Lignin-like compounds dominated permafrost-thaw, followed by lipid- and protein-like compounds. However, under anoxic incubation conditions, there was accumulation of lipid-like compounds and reduction in the nominal oxidation state of C over time, regardless of the compound classes. DOM dynamics may be affected by microbial activity and abiotic processes mediated by Fe-minerals related to selective DOM fractionation and/or its oxidation. Chemodiversity DOM signatures could serve as valuable proxies to track redox conditions with permafrost-thaw.

Analysis and partitioning of terrestrial water storage in the Yellow River source region

AbstractIn order to increase the capability to understand and quantify the spatial differences in terrestrial water storage (TWS), and to reflect the unique energy balance processes and soil freeze–thaw mechanisms in the Qinghai‐Tibet Plateau (QTP), this study improved the energy balance processes of the water and energy transfer processes model, including its surface radiation calculations and snowmelt module. By integrating these improvements, a water and energy transfer processes model in Qinghai‐Tibet Plateau (WEP‐QTP) for the Yellow River source region (YRSR) is developed. Using the improved WEP‐QTP model to perform simulations, we assessed the daily changes in snow cover, soil moisture (SM), permafrost (PM), and groundwater storage (GWS) in the YRSR. Our analysis revealed an increase in TWS of 0.24 mm/yr from 1961 to 2020. Snow water equivalent (SWE), SM, PM, and GWS have proportional contributions of 8.33%, 216.67%, −154.17%, and 29.17% to the increased TWS, respectively. SM is the primary component of TWS. Temperature (T), precipitation (P), evapotranspiration (E), and solar radiation (Rs) influence the spatiotemporal variations in TWS, as well as those of its components. The increase in P is the primary cause for the rise in TWS, SWE, and SM, while the increase in T predominantly contributes to the decrease in PM. Furthermore, permafrost degradation and climate‐induced warming and humidification lead to increased infiltration, resulting in elevated GWS.

Taxonomic and metabolic diversity of Actinomycetota isolated from faeces of a 28,000-year-old mammoth.

Ancient environmental samples, including permafrost soils and frozen animal remains, represent an archive with microbial communities that have barely been explored. This yet unexplored microbial world is a genetic resource that may provide us with new evolutionary insights into recent genomic changes, as well as novel metabolic pathways and chemistry. Here, we describe ActinomycetotaMicromonospora, Oerskovia, Saccharopolyspora, Sanguibacter and Streptomyces species were successfully revived and their genome sequences resolved. Surprisingly, the genomes of these bacteria from an ancient source show a large phylogenetic distance to known strains and harbour many novel biosynthetic gene clusters that may well represent uncharacterised biosynthetic potential. Metabolic profiles of the strains display the production of known molecules like antimycin, conglobatin and macrotetrolides, but the majority of the mass features could not be dereplicated. Our work provides insights into Actinomycetota isolated from an ancient source, yielding unexplored genomic information that is not yet present in current databases.

ВОЗДЕЙСТВИЕ ИЗМЕНЕНИЯ КЛИМАТА НА ЗДОРОВЬЕ НАСЕЛЕНИЯ В РОССИИ. ПРИОРИТЕТНЫЕ НАПРАВЛЕНИЯ АДАПТАЦИИ (АНАЛИТИЧЕСКИЙ ОБЗОР)

A review of the studies assessing the impact of climate change on public health is presented. Taking into account climatic features of various regions, priority tasks of the National Plan for Adaptation to Climate Change are identified. The tasks include: establishing threshold values for high temperatures based on assessing health risks, including mental health; creating a monitoring system for the concentration of allergenic plant pollen and the prevalence of allergic diseases; developing prevention systems for outdoor and indoor workers at extremely high temperatures (optimum work and rest conditions); improving the epidemiological surveillance system for climate-related infectious diseases, in particular, organizing microbiological monitoring of permafrost soils. Special adaptation plans are needed for indigenous peoples of the Arctic region.

Determination of controlled parameters for designing a network for geotechnical monitoring of underground pipelines in the cryolithozone

Relevance. Determined by the need for geotechnical monitoring in the areas of distribution of permafrost soils for underground pipelines. The geotechnical system “permafrost soil – underground pipeline” is subject to the influence of exogenous geological processes during operation, cyclical changes in the state of soils of the seasonal layer of thawing and freezing, thawing of permafrost soils from the thermal effect of the pipeline, changing the plan-altitude position. The variety of schemes for interaction of the pipeline body with varieties of lithological structure of permafrost soils along the route should be worked out in detail at the design stage and also assessed in detail during geotechnical monitoring of the pipeline. The lack of regulatory requirements for the monitored parameters of underground pipelines leads to the use of non-standardized and varied monitoring networks from project to project. The lack of standard values ​​for the maximum deformations of an underground pipeline leads to the need to use calculation methods for determining the maximum deformations of the base and pipeline. The authors proposed the use of a comprehensive methodology for calculating underground pipelines, developed by employees of JSC TomskNIPIneft to determine the maximum permissible deformations of the pipeline at each point of the route with the presence of permafrost soils at the design stage, with further use of the results obtained as a controlled criterion when conducting geotechnical monitoring. Aim. To determine the controlled parameters for geotechnical monitoring of underground pipelines in the cryolithozone at the operational stage based on the application of a comprehensive methodology for calculating underground pipelines, as well as the formation of requirements for the system of information points. Methods. Review of the regulatory framework for geotechnical monitoring, analysis and evaluation of the applied methods and designs for monitoring underground pipelines, analysis of a comprehensive methodology for calculating underground pipelines in relation to the purposes of geotechnical monitoring. Results. Based on the results of the review of regulatory and technical documentation, the authors have revealed a lack of specification of methods, equipment, volume of the geotechnical monitoring network and frequency of pipeline monitoring, as well as the requirement for the use of the calculation method of limiting deformations and the lack of description of possible methods. A detailed analysis of the complex methodology for pipeline calculations, developed at JSC TomskNIPIneft, substantiates its use for geotechnical monitoring purposes, and notes the advantage of the methodology in the detail of the obtained limit values ​​of deformation with an accuracy of one meter along the axis of the pipeline route. The authors studied the methods and designs used for monitoring deformations of underground pipelines and established the compatibility of using a complex methodology with any design and method of monitoring. The paper introduces the list of the main monitored parameters and justification for the scope of the geotechnical monitoring network for underground pipelines.

Thermal photogrammetry on a permafrost rock wall for the active layer monitoring

Permafrost and active layer models often cannot explain the high spatial variability, especially in heterogeneous environments like the mountainous regions due to their scarce resolution, paucity of climatic data and topographic details. In this study, we want to introduce a new application of the unmanned aerial vehicle (UAV) in thermal photogrammetry to model the active layer thickness (ALT) of an alpine rock wall through the computation of the thermal inertia and compare the results with a widespread ALT model. On the Gran Zebrù South rock wall, 8 thermal UAV surveys has been conducted in 4 different summer days during 2021-2022 in order to have two 3D thermal models per day at different solar radiation inputs. By analyzing topographic data, visible imagery and the thermal models, the apparent thermal inertias (ATIs) have been converted into heat transfer coefficients (HTCs) and then into ALT of 2021 and 2022. These maps have been validated through the placement of thermistors at different elevations and with variable depths (2, 15 and 40 cm from the rock surface).The resulting ALT has been compared with the Stefan's solution and the alpine permafrost index map (APIM), which showed large underestimations and a noncorrespondence with permafrost occurrence. The average ALT increase of 29.3 cm from 2021 to 2022 has been discussed regarding permafrost formation/degradation future trend under the climatic change and potential risks of alpine areas.

Triggers of present-day rockfalls in the zone of sporadic permafrost in non-glaciated mountain region: the case study of Turnia Kurczaba (the Tatra Mts., Poland)

In recent decades there has been growing evidence of the impact of ongoing climate warming on the frequency of rockfalls. However, these are not adequately documented, especially in non-glaciated, high mountain regions of middle latitude. This study comprehensively documents the Turnia Kurczaba rockfall, one of the most significant rockfalls recorded in recent decades in the Tatra Mountains. The precise projections of the volumes and distribution of rock losses and deposits, the determination of the trajectories, modes and speeds of movement of rock material, as well as information on the geological, morphological, and meteorological conditions behind the Turnia Kurczaba rockfall form a unique dataset. The data documents a spectacular episode in the contemporary development of a complex slope system in the Tatras in an all-encompassing way and can be used to validate and calibrate existing models and improve numerical simulations of other rockfalls, both for hazard and risk assessment and slope evolution studies. Moreover, in the context of archival data, they demonstrate that in the Tatra sporadic permafrost zone, only relatively small rockfalls have been recorded in recent decades. Their cause was not the degradation of permafrost but freeze-thaw processes with the co-participation of rainwater and meltwater. The largest of these occur within densely fractured cataclysites, mylonites, and fault breccias. The impact of rockfalls on the morphodynamics of talus slopes is uneven in the storied arranged rock-talus slope systems. Even colluviums belonging to the same slope system can differ in their development rate and regime, and different thermal and wetness drivers can control their evolution.

Lithological controls of the Mg isotope composition of the Lena River across seasons and its impact on the annual isotope flux to the Arctic Ocean

Given the importance of permafrost regions in providing the major elements to the Arctic Ocean, and the vulnerability of these regions to ongoing climate change due to permafrost thaw and landscape modifications, assessing the magnitude and characterizing the factors governing isotope compositions in river waters across seasons and space is of high priority.Towards identifying possible environmental controlling factors (climate, vegetation, rock lithology) and quantifying annual fluxes of dissolved Mg isotopic signatures in large Arctic rivers located in the continuous permafrost zone, here we measured hydrochemical and Mg isotope compositions of the Lena River main channel and its various tributaries over different seasons of the year. In general, we did not find evidence of any statistically significant (p < 0.05) correlation between δ26Mg and main physico-geographical parameters of the river watersheds (temperature, permafrost, type of vegetation). The exception is the decrease in riverine δ26Mg values that was accompanied by an increase in the carbonate rock proportion in the watershed, whereas an opposite trend was observed for the abundance of terrigenous and silicate rocks. An incontestable control of dolomite rocks on Mg isotope signature in the Lena River was also supported by decreasing δ26Mg values with increasing Dissolved Inorganic Carbon (DIC) concentration, as also observed for other Artic River basins. This relationship was mostly pronounced during the high-flow period, when secondary Mg silicate formation in soils and underground waters and so the terrestrial uptake of Mg were the lowest. In the Lena River main channel, the lowest δ26Mg values (−1.5 ± 0.05 ‰) were observed during autumn-winter (September to March), probably reflecting a dominant role of underground reservoirs and subsurface soil weathering of isotopically light Precambrian dolomites.The mean δ26Mg values of the Lena River during two months of spring (−1.02 to −1.28 ‰), 4 months of summer baseflow (−1.30 ‰) and 6 months of winter yields a mean discharge-weighted annual value of −1.26 ± 0.05 ‰. This number coincides with the value of summer baseflow reported in earlier works. Therefore, like in the recently studied Yenisey River basin, the Mg isotope signature of the Lena River water likely stems from a mixture of carbonate (−2.0 ≥ δ26Mg ≥ −2.5 ‰) and silicate (0 ≥ δ26Mg ≥ −0.2 ‰) rocks in its watershed. We also argue that the discharge-weighted mean annual isotopic signature of an element in the Artic rivers can be reasonably approximated by a single sampling campaign during summer baseflow. This allows cost-effective assessment of mean riverine isotopic signatures of other elements in both small and large rivers to the Arctic Ocean.

Environmental factors controlling soil warming and wetting during 2000–2020 in permafrost and non-permafrost regions across the Qinghai–Tibet Plateau

The Qinghai–Tibet Plateau (QTP) has experienced rapid environmental changes, including climate warming and wetting, since the 1980s. These environmental changes significantly impact the shallow soil hydrothermal conditions, which have key roles in land–atmosphere feedback and ecosystem functions. However, the spatial variations and responses of soil hydrothermal conditions to environmental changes over the QTP with permafrost (PF) and seasonal frost (SF) remain unclear. In this study, we investigated the spatial variations in soil temperature (ST) and soil moisture (SM) changes over the QTP from 2000 to 2020 using 99 in-situ sites with observations at 4 depths (i.e. 10, 40, 100 and 200 cm). The main environmental controlling factors were further identified using a calibrated statistical model. Results showed that significant (p < 0.05) soil warming occurred at multiple soil layers during 2000–2020 with a wide variation (i.e. 0.033–0.039 °C per year on average), whereas the warming rates at PF sites were two times greater than those at SF sites. In addition, the soil wetting rate was high over the SF region, whereas the soil wetting rate was low over the PF region. Aside from air temperature, changes in thawing degree days and solar radiation (Srad) contributed most to soil warming in the PF region, whereas changes in rainfall, Srad and evaporation (EVA) have been identified as the key factors in the SF region. As for soil wetting, changes in snowfall, freezing degree days and vegetation have noticeable nonlinear effects over the PF region, whereas changes in EVA, Srad and rainfall highlighted distinct linear and nonlinear effects in the SF region. These findings enhance our understanding of the hydrothermal impacts of future environmental changes over the QTP.

Thermokarst lakes are hotspots of antibiotic resistance genes in permafrost regions on the Qinghai-Tibet Plateau

Antibiotic resistance genes (ARGs) are natural products and emerging pollutants in remote environments, including permafrost regions that are rapidly thawing due to climate warming. We investigated the role of thermokarst lakes (including sediment and water) in reserving ARGs compared to permafrost soils across the permafrost regions on the Qinghai-Tibet Plateau. As intrinsically connected distinct environments, permafrost soil, lake sediment, and lake water harbored 1239 ARGs in total, while a considerable number of same ARGs (683 out of 1239) concurrently presented in all these environments. Soil and sediment had a higher number of ARGs than water. Multidrug resistance genes were the most diverse and abundant in all three environments, where cls, ropB, mdfA, fabI, and macB were the top five most abundant ARGs while with different orders. Soil and sediment had similar ARG profiles, and the alpha and beta diversity of ARGs in sediment were positively correlated with that in soil. The beta diversity of ARG profiles between sediment and soil was highly contributed by turnover component (89%). However, turnover and nestedness components were almost equality contributed (46%–54%) to the beta diversity of ARG profiles between soil and water as well as between sediment and water. The results suggested that thermokarst lake sediments might inherit the ARGs in permafrost soils. Water ARGs are the subset of soil ARGs and sediment ARGs to a certain degree with species turnover playing a significant role. When accounting the ARGs in sediment and water together, thermokarst lakes had a significantly higher number of ARGs than permafrost soils, suggesting that thermokarst lakes act as the hotspots of ARGs in permafrost regions. These findings are disturbing especially due to the fact that tremendous number of thermokarst lakes are forming under accelerating climate change.

Non-local modelling of freezing and thawing of unsaturated soils

A large part of the earth’s surface is covered by seasonally or permanently frozen soils. Considering the negative impact of climate change, future development of such regions can be underpinned by mathematical methods for accurate analysis of heat and moisture transport in freezing and thawing soils. Reported in this paper is a novel non-local formulation of water and heat transport in unsaturated soils. The formulation uses bond-based peridynamics (PD) and consists of a set of integral–difference formulations of energy and mass conservation. Specific features of freezing/thawing soils are incorporated by a combination of van Genuthcen and Clausius–Clapeyron relations. Computational results are compared with four sets of laboratory experiments to demonstrate the efficiency of the developed approach. The model can be used to analyse the effect of water flow on heat transfer in soils during thawing of permafrost soils. Further, it can be applied in modelling climate change effects, and can be used for construction of coupled physically justified models of frost heave.

A regime shift between soil moisture and temperature in the 1950s over the permafrost region of Northeast China

AbstractPermafrost is one of the essential carbon pools in the world. Due to limited studies on historical soil moisture changes and the coupling relationship between soil moisture and temperature in permafrost regions, significant uncertainty exists in the carbon loss in permafrost predicted by different models under global warming scenarios. Based on the tree‐ring width chronology of Pinus sylvestris var. mongholica Litv. growing in the southern edge of the Eurasian continuous permafrost zone, we reconstructed the summer (June–September) 0–1 m soil moisture variations from 1705 to 2009, which could explain 45.6% of the variance in the observed soil moisture. Overall, local precipitation and temperature exhibited statistically significant positive feedback (p &lt; 0.001) to soil moisture before the 1950s, indicating that the warm/humid climate pattern was conducive to soil moisture conservation before the Anthropocene Epoch. However, the effect of temperature on soil moisture has shifted suddenly to negative since the 1950s, implying that the positive soil moisture‐temperature relationship during the past three centuries has been disrupted by the unprecedented warming in the Modern Warm Period. Furthermore, we found that the temporal relationship of the soil moisture‐temperature (15‐year sliding correlation) in the study area is negatively regulated by the global mean temperature variations (p &lt; 0.01). The regime shift between soil moisture and temperature might be attributed to the superimposed influence of natural and anthropogenic factors since the 1950s. Although the warming leads to the melting of the permafrost layer, and thus the increase in soil moisture content, the enhanced evapotranspiration caused by warming up results in more water loss and drier soil. This study provides historical evidence of shifted soil moisture‐temperature coupling in the permafrost zone, warning that soil moisture in the permafrost region may further decline under global warming scenarios, thereby affecting vegetation growth and forest carbon sequestration potential.

Soil research in Yakutia at the turn of the 20th–21st centuries

The main patterns of soil cover development in Yakutia and the morphogenetic features of permafrost soils were identified in the first few years of the 20th century by researchers representing the scientific school of V.V. Dokuchaev. The soil scientists of the Complex Expedition of the USSR Academy of Sciences between 1925 and 1930 significantly broadened the scope of soil-geographical research. The Yakut School of Soil Science emerged during the post war period. The works of Yakut scientists on the study of permafrost soils throughout the republic and soil maps of various scales have earned recognition from soil scientists of the Soviet Union. In the 1990s, the modern era of soil science development in Yakutia began on an international scale.

Post-fire soil carbon emission rates along boreal forest fire chronosequences in northwest Canada show significantly higher emission potentials from permafrost soils compared to non-permafrost soils

Boreal forests are one of the most important biomes storing carbon (C). Wildfires burn yearly on average more than 1% of the boreal forest, and it is expected that the fire return intervals will shorten due to climate change. Fire is one of the most influential factors affecting soil organic matter quantity and quality, soil C pools, and presumably also the time C resides in the soil (soil C turnover time in years). We compared the potential effects of forest fire through post-fire succession on soil carbon dioxide (CO2) emission rates and soil C turnover time in two fire chronosequences, one with underlying permafrost soil and the other without permafrost. We found that fire had a significant effect on potential soil C turnover times, but surprisingly there was no significant difference in soil C turnover times between the permafrost and non-permafrost areas, although the soil CO2 emissions rates in permafrost areas are approximately three times higher compared to non-permafrost areas. In recently burned areas the potential soil C turnover times were two times longer compared to control areas located in forests burned more than 100 years ago. The longest potential soil C turnover times were recorded in mineral soil layers (30 cm) of permafrost soils, and the shortest potential soil C turnover times were recorded in humus layers of non-permafrost areas.

Geographical and genetic features of soil formation and diversity of the permafrost soils of Central Yakutia

The aim of the study. The aim of this article was to identify the geographical and genetic features of soil formation in the cryolithozone of Central Yakutia and to assess the diversity of all types of permafrost soils of this territory. Location and time of the study. Soil-geographical and soil-genetic studies were carried out near the Middle Lena, on the territory of Central Yakutia within various geomorphological tiers of the Central Yakut Plain at different times, starting from the 1990s. Methodology. In carrying out these works, widely used methods of soil research were used, such as comparative geographical, profile genetic and comparative analytical in combination with well-known and commonly used analytical methods. At the same time, all the main results of soil studies conducted on this territory by our predecessor permafrost soil scientists were taken into account in a comparative aspect. Main results. According to the obtained results, it is necessary to state that this region of the cryolithozone is characterized by extremely peculiar landscape and climatic conditions of soil formation, the formation of the cryogenic soils occurring in a cryoarid climate, mainly on loose alluvial deposits of various ages, under forest and meadow-steppe vegetation and continuous permafrost. In the studied territory, the cryogenic soil-forming processes are crucial for the development of properties, composition and regimes of these permafrost soils, causing their high diversity and diversity of the soil cover of Central Yakutia. The systematic list of permafrost soils of the studied territory includes 17 types and 21 subtypes of soils and is forecasted to expand as the study of the soil cover of this unique region of the cryolithozone deepens. At the same time, the diversity of soils there is formed by the six types of zonal and azonal forest, five types of meadow-steppe and five intrazonal types of the permafrost soils. A broader concept of "permafrost soils" is proposed, in contrast to that interpreted in the current classification of soils of Russia and WRB, the essence of which is that regardless of the depth of seasonal thawing, all soils underlain by the permafrost are called permafrost soils. In these soils, the interlocking of seasonally and permanently frozen layers is observed in winter. These soils may differ in pronounced cryomorphic features (cryozems, fawn) or not have them (podburs, podzols, chernozems), being characterized by a permafrost type of temperature regime. Conclusion. In the cryolithozone environment of Central Yakutia, elementary soil-forming processes occur under cryogenesis conditions, which in the general hierarchy of soil-forming factors is considered at the subfactorial level; minor variations of the soil-forming factors can change the directions and rates of the soil-forming processes and, ultimately, lead to a high degree of diversity and contrast in the soil cover of the studied territory.

Depth-related microbial communities and functional genes in alpine permafrost

&lt;p&gt;Permafrost microorganisms have received increased attention due to their critical role in biogeochemical cycles and the potential biosafety risks associated with climate warming. However, knowledge regarding the depth-related community structure and function of permafrost microorganisms remains limited. In this study, we employed metagenomic methods to investigate microbial communities, functional genes, and their controlling factors in alpine permafrost of the Shule River headwaters on the northeastern margin of the Qinghai-Tibet Plateau. A total of 287 metagenome-assembled genomes were constructed, representing 20 bacterial phyla and 1 archaeal phylum. Additionally, we identified &lt;styled-content style-type="number"&gt;2079&lt;/styled-content&gt; viral contigs spanning more than 14 viral families, with approximately 67% constituting previously unknown taxa, forming a unique virome in alpine permafrost compared to other regions. Significant variations in bacterial and viral compositions, along with their metabolic potentials, were observed across vertical profiles from the active layer to the permafrost table layer. Viral diversity showed an initial increase followed by a decrease, reaching the maximum at the depth of 90-140 cm. We identified abundant genomic capabilities related to carbon, nitrogen, and sulfur cycling. Moreover, our analysis revealed 60 auxiliary metabolic genes in viruses and 7,000 putative biosynthetic gene clusters for secondary metabolites from 21 prokaryotic phyla. Soil temperature emerged as the most significant environmental variable influencing the composition of microbial communities and functional genes, as well as the diversity of microbial communities. These results offer valuable insights into the potential functional transformations and biosafety risks mediated by permafrost microorganisms under future warming.&lt;/p&gt;

Permafrost degradation and soil erosion as drivers of greenhouse gas emissions from tundra ponds

Climate change poses a serious threat to permafrost integrity, with expected warmer winters and increased precipitation, both raising permafrost temperatures and active layer thickness. Under ice-rich conditions, this can lead to increased thermokarst activity and a consequential transfer of soil organic matter to tundra ponds. Although these ponds are known as hotspots for CO2 and CH4 emissions, the dominant carbon sources for the production of greenhouse gases (GHGs) are still poorly studied, leading to uncertainty about their positive feedback to climate warming. This study investigates the potential for lateral thermo-erosion to cause increased GHG emissions from small and shallow tundra ponds found in Arctic ice-wedge polygonal landscapes. Detailed mapping of fine-scale erosive features revealed their strong impact on pond limnological characteristics. In addition to increasing organic matter inputs, providing carbon to heterotrophic microorganisms responsible for GHG production, thermokarst soil erosion also increases shore instability and water turbidity, limiting the establishment of aquatic vegetation—conditions that greatly increase GHG emissions from these aquatic systems. Ponds with more than 40% of the shoreline affected by lateral erosion experienced significantly higher rates of GHG emissions (∼1200 mmol CO2 m−2 yr−1 and ∼250 mmol CH4 m−2 yr−1) compared to ponds with no active shore erosion (∼30 mmol m−2 yr−1 for both GHG). Although most GHGs emitted as CO2 and CH4 had a modern radiocarbon signature, source apportionment models implied an increased importance of terrestrial carbon being emitted from ponds with erosive shorelines. If primary producers are unable to overcome the limitations associated with permafrost disturbances, this contribution of older carbon stocks may become more significant with rising permafrost temperatures.

Roles and activities of local stakeholders facing Alpine permafrost warming: A comparative exploratory analysis of three contexts and networks of actors

Mountain permafrost warming resulting from climate change increases gravitational hazards. This interdisciplinary study compares the networks of actors involved in managing such hazards in three regions of the European Alps. Interviews were conducted with 40 people (members of local authorities, mountain professionals, and private citizens) at the foot of Mont Blanc (Chamonix, France), in the Vanoise massif (France), and in the canton of Valais (Switzerland). Data were analysed qualitatively and quantitatively using interaction matrices and network diagrams. Communal authorities played a central role but partnered with many other public and private actors. In Valais, collaboration to protect infrastructure and inhabited areas was centred around communal and cantonal authorities. In Chamonix, the network of actors gave a significant role to mountain professionals. In Vanoise, the network was less dense and less well-defined, although actors had high expectations regarding awareness-raising and prevention. Sources of tension existed in all three networks, particularly between authorities and mountain professionals. To strengthen community resilience, authorities should develop more mechanisms for citizen participation in risk management.

Emerging investigator series: preferential adsorption and coprecipitation of permafrost organic matter with poorly crystalline iron minerals.

Future permafrost thaw will likely lead to substantial release of greenhouse gases due to thawing of previously unavailable organic carbon (OC). Accurate predictions of this release are limited by poor knowledge of the bioavailability of mobilized OC during thaw. Organic carbon bioavailability decreases due to adsorption to, or coprecipitation with, poorly crystalline ferric iron (Fe(III)) (oxyhydr)oxide minerals but the maximum binding extent and binding selectivity of permafrost OC to these minerals is unknown. We therefore utilized water-extractable organic matter (WEOM) from soils across a permafrost thaw gradient to quantify adsorption and coprecipitation processes with poorly crystalline Fe(III) (oxyhydr)oxides. We found that the maximum adsorption capacity of WEOM from intact and partly thawed permafrost soils was similar (204 and 226 mg C g-1 ferrihydrite, respectively) but decreased to 81 mg C g-1 ferrihydrite for WEOM from the fully thawed site. In comparison, coprecipitation of WEOM from intact and partly thawed soils with Fe immobilized up to 925 and 1532 mg C g-1 Fe respectively due to formation of precipitated Fe(III)-OC phases. Analysis of the OC composition before and after adsorption/coprecipitation revealed that high molecular weight, oxygen-rich, carboxylic- and aromatic-rich OC was preferentially bound to Fe(III) minerals relative to low molecular weight, aliphatic-rich compounds which may be more bioavailable. This selective binding effect was stronger after adsorption than coprecipitation. Our results suggest that OC binding by Fe(III) (oxyhydr)oxides sharply decreases under fully thawed conditions and that small, aliphatic OC molecules that may be readily bioavailable are less protected across all thaw stages.