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Thermokarst lake formation and evolution in ice-rich permafrost in the (a–d) continuous and (e–h) discontinuous zones (modified from Grosse et al. (2013) and Calmels et al. (2008), respectively). In continuous permafrost, where ice-wedge terrains dominate (a), thermokarst lake inception generally starts with water pooling above low-center polygons and melting ice wedges (b). These small ponds eventually merge to create shallow lakes (c), which further deepen and develop laterally by thermo-erosion, resulting in larger and deeper mature lakes with an underlying thaw bulb or talik (d). In discontinuous permafrost, where ice-rich cryogenic mounds (palsas and lithalsas) are widespread (e), the melting of segregation ice lenses results in surface subsidence and water pooling in topographic depressions (f and g). Once permafrost has completely thawed, a mature thermokarst pond/lake surrounded by a peripheral ridge can stabilize if underlain by impermeable silts and clays (h). The final stage of thermokarst lakes can involve: rapid drainage (resulting from shoreline breaching after higher-than-average precipitation), lake level drawdown (due to factors that lead to increased evaporation), subsurface drainage (groundwater infiltration through an open talik), or terrestrialization (via rapid peat accumulation and (or) lake infilling). See text for details and references
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Widespread across northern permafrost landscapes, thermokarst ponds and lakes provide vital wildlife habitat and play a key role in biogeochemical processes. Stored in the sediments of these typically shallow and dynamic waterbodies are rich sources of paleoenvironmental information whose potential has not yet been fully exploited, likely because o...
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Citations
... The interface between the active and frozen layers creates a sliding surface, and the thawed soil slowly glides downslope under its weight to form a mudflow [100]. Forest fires result in the increasing the amount of latent heat that can enter the ground, increasing soil temperatures, melting ground ice, triggering permafrost degradation, and affecting permafrost landscapes [20] via surface subsidence [75,101] and the formation of thermokarst ponds and lakes [74,102,103]. Forty percent of the permafrost in the northern hemisphere is affected by thermokarst subsidence, and new thermokarst landforms are constantly forming [104]. Due to permafrost degradation on the Tibetan Plateau, the total number of thermokarst lakes and ponds increased by 534, and the total area increase by 4.1 × 10 6 m 2 from 1969 to 2010 [105]. ...
... With increasing fire intensity, the thickness of the active layer increases [98], and the soil moisture content decreases [93]. Forest fires cause permafrost degradation, destroy permafrost structures, and cause the formation of geological landscapes, such as surface settlements, thaw depressions, and thermokarst lakes [74,102,103]. Through research and investigations of the physical and chemical properties of permafrost, we can understand the specific impact of forest fire disturbance on permafrost and provide a scientific basis for forest and wetland protection and ecological environment restoration in cold regions. ...
The frequency of forest fires has increased dramatically due to climate change. The occurrence of forest fires affects the carbon and nitrogen cycles and react to climate change to form a positive feedback mechanism. These effects further impact the distribution of microbial biomass carbon (MBC) and microbial biomass nitrogen (MBN) and the soil microbial community structure. In addition, permafrost degradation can significantly affect the microorganisms in the soil. Based on these findings, this review examines the effects of fire intensity and post-fire recovery time on permafrost, the soil microbial community, MBC, MBN, and their interrelationships. This review demonstrated that (1) fires alter the condition of surface vegetation, reduce the organic layer thickness, redistribute snow, accelerate permafrost degradation, and even lead to permanent changes, where the restoration of the pre-fire state would require several decades or even centuries; (2) soil microbial community structure, soil MBC, and MBN negatively correlate with fire intensity, and the effects become more pronounced with increasing fire intensity; and (3) the structural diversity and stability of the soil microbial community were improved with time, and the amount of MBC and MBN increases as the years after a fire go by; it would still take more than ten years to recover to the pre-fire level. However, the relationship between permafrost degradation and soil microbes after forest fires is still unclear due to a lack of quantitative research on the mechanisms underlying the changes in soil microorganisms resulting from fire-induced permafrost degradation. Therefore, expanding quantitative studies and analyses of the mechanisms of interactions between forest fires, permafrost, and soil microorganisms can provide a scientific basis for understanding ecosystem carbon pools and dual-carbon targets in Arctic–boreal permafrost regions.
... In some cases disturbance by water movements and biological redistribution of sediments by benthic macroinvertebrates (Chapter 21), termed bioturbation, can be sufficient to obscure dating chronology, particularly in shallow lakes (e.g., Bennion et al., 2010). However, in most cases careful interpretation of recent dating analyses, combined with other paleolimnological data, provides much insight into the reconstruction of past lake events (e.g., Bouchard et al., 2017). ...
... TLPs play a vital role in the hydrological-thermal energy exchange between atmosphere and subsurface (Jones et al., 2022) and serve as a key indicator in understanding permafrost degradation (Xu et al., 2023). In addition, TLPs provide the necessary wildlife habitats (Bouchard et al., 2016), as well as water sources for industrial activities and human society (Bogdanova et al., 2023;White et al., 2007). However, it has been confirmed that TLPs have exacerbated permafrost degradation through thermal and mechanical processes in the circumpolar Arctic (Brouchkov et al., 2004;West & Plug, 2008), as well as in the QXP (Lin et al., 2016;Ling et al., 2012;Luo et al., 2022;Peng et al., 2021;Șerban et al., 2021). ...
... An obvious year-on-year increment in soil temperature and moisture has been witnessed in the Lena Basin, resulting in a rapid increase in permafrost thaw (Dzhamalov et al., 2012;Gautier et al., 2021;Iijima et al., 2010). The recent warming and wetting trends of climate, together with the impact from changing permafrost, have altered the dynamics of TLPs in the Arctic (Bouchard et al., 2016;Morgenstern et al., 2011;Muster et al., 2017). However, the distribution of TLPs for the entire Lena Basin still remains relatively unknown. ...
... To what extent primary production of OM within the lake contributed to the lake SOC pool was not quantified here. Aquatic production in thermokarst lakes can be significant with increases in nutrient supply (Bouchard et al. 2017) and offset the GHG release from the lake systems over millenial timescales (Walter Anthony et al. 2014). However, primary production of high latitude lakes is known to be low due to the cold Fig. 9 Schematic overview of field site for both lakes during summer and winter season. ...
Thermokarst lakes are important conduits for organic carbon sequestration, soil organic matter (soil-OM) decomposition and release of atmospheric greenhouse gases in the Arctic. They can be classified as either floating-ice lakes, which sustain a zone of unfrozen sediment (talik) at the lakebed year-round, or as bedfast-ice lakes, which freeze all the way to the lakebed in winter. Another key characteristic of thermokarst lakes are their eroding shorelines, depending on the surrounding landscape, they can play a major role in supplying the lakebeds with sediment and OM. These differences in winter ice regime and eroding shorelines are key factors which determine the quantity and quality of OM in thermokarst lake sediments. We used an array of physical, geochemical, and microbiological tools to identify the differences in the environmental conditions, sedimentary characteristics, carbon stocks and microbial community compositions in the sediments of a bedfast-ice and a floating-ice lake in Far East Siberia with different eroding shorelines. Our data show strong differences across most of the measured parameters between the two lakes. For example, the floating-ice lake contains considerably lower amounts of sediment organic matter and dissolved organic carbon, both of which also appear to be more degraded in comparison to the bedfast-ice lake, based on their stable carbon isotope composition (δ ¹³ C). We also document clear differences in the microbial community composition, for both archaea and bacteria. We identified the lake water depth (bedfast-ice vs. floating-ice) and shoreline erosion to be the two most likely main drivers of the sedimentary, microbial and biogeochemical diversity in thermokarst lakes. With ongoing climate warming, it is likely that an increasing number of lakes will shift from a bedfast- to a floating-ice state, and that increasing levels of shoreline erosion will supply the lakes with sediments. Yet, still little is known about the physical, biogeochemical and microbial differences in the sediments of these lake types and how different eroding shorelines impact these lake systems.
... Conditions affecting permafrost degradation are often heterogeneous, leading to a diversity of thermokarst lake formation processes [64]. As for susceptibility evaluation, there are no fixed screening criteria for conditioning factors. ...
Abstracts
The rapidly warming climate on the Qinghai–Tibet Plateau (QTP) leads to permafrost degradation, and the thawing of ice-rich permafrost induces land subsidence to facilitate the development of thermokarst lakes. Thermokarst lakes exacerbate the instability of permafrost, which significantly alters regional geomorphology and hydrology, affecting biogeochemical cycles. However, the spatial distribution and future changes in thermokarst lakes have rarely been assessed at large scales. In this study, we combined various conditioning factors and an inventory of thermokarst lakes to assess the spatial distribution of susceptibility maps using machine-learning algorithms. The results showed that the extremely randomized trees (EXT) performed the best in the susceptibility modeling process, followed by random forest (RF) and logistic regression (LR). According to the assessment based on EXT, the high- and very high-susceptibility area of the present (2000–2016) susceptibility map was 196,222 km², covering 19.67% of the permafrost region of the QTP. In the future (the 2070s), the area of the susceptibility map was predicted to shrink significantly under various representative concentration pathway scenarios (RCPs). The susceptibility map area would be reduced to 37.06% of the present area in RCP 8.5. This paper also performed correlation and importance analysis on the conditioning factors and thermokarst lakes, which indicated that thermokarst lakes tended to form in areas with flat topography and high soil moisture. The uncertainty of the susceptibility map was further assessed by the coefficient of variation (CV). Our results demonstrate a way to study the spatial distribution of thermokarst lakes at the QTP scale and provide a scientific basis for understanding thermokarst processes in response to climate change.
... 37 Based on paleolimnological evidence and aerial images, OCF 48 experienced a drainage event in ∼1989 and has since been refilled. 46,47 Paleolimnological evidence for OCF 46 suggests increased thermokarst activity began in the 1970s and may have been followed by a drainage event. 47 OCF 11 also has notably unique catchment characteristics with dense willow shrub surrounding the lake that suggests previous higher water levels, but remote sensing images suggest surface water levels have remained relatively stable since 1951. ...
... 46,47 Paleolimnological evidence for OCF 46 suggests increased thermokarst activity began in the 1970s and may have been followed by a drainage event. 47 OCF 11 also has notably unique catchment characteristics with dense willow shrub surrounding the lake that suggests previous higher water levels, but remote sensing images suggest surface water levels have remained relatively stable since 1951. 11 ...
Shallow waterbodies are abundant in Arctic and subarctic landscapes where they provide productive wildlife habitat and hold cultural and socioeconomic importance for Indigenous communities. Their vulnerability to climate-driven hydrological and limnological changes enhances a need for long-term monitoring data capable of tracking aquatic ecosystem responses. Here, we evaluate biological and inferred physicochemical responses associated with a rise in rainfall-generated runoff and increasingly positive lake water balances in Old Crow Flats (OCF), a 5600 km ² thermokarst landscape in northern Yukon. This is achieved by analyzing periphytic diatom community composition in biofilms accrued on artificial-substrate samplers at 14 lakes collected mostly annually during 2008–2019 CE. Results reveal that diatom communities at 10 of the 14 lakes converged toward a composition typical of lakes with rainfall-dominated input waters. These include six of nine lakes that were not initially dominated by rainfall input. The shifts in diatom community composition infer rise of lake-water pH and ionic content, and they reveal that northern shallow lake ecosystems are responsive to climate-driven increases in rainfall. Based on data generated during the 12 -year-long monitoring period, we conclude that lakes located centrally within OCF are most vulnerable to rapid climate-driven hydroecological change due to flat terrain, larger lake surface area, and sparse terrestrial vegetation, which provide less resistance to lake expansion, shoreline erosion, and sudden drainage. This information assists the local Indigenous community and natural resource stewardship agencies to anticipate changes to traditional food sources and inform adaptation options.
... We specifically investigated the movement of the bank of its approximately 1.5 m deep thermokarst pond (Figure 1d). These thermokarst ponds are common in circumpolar regions and thus affect the hydrology of river systems (Bouchard et al., 2016). The river is straight with strong anthropological influences (e.g. ...
Bank erosion impacts sediment transport and river morphology, both important processes for river managers. Some important factors, such as timing and causes of bank erosion are difficult to assess with established techniques. We explore the capability of smart sensors, actually developed for the agricultural sector, to measure soil moisture and temperature as well as movement in real-time on banks of northern rivers in different geographical, climatological and landscape settings. Soil movement and its timing were easy to identify from the measurements and in many cases the reason for the onset of movement could be inferred. The sensors automatically upload data with a high temporal resolution for a long period of time, while only minimally disturbing the bank itself. However, the sensor approach has a low spatial resolution (point measurements) and therefore complementing the measurements with approaches with a high spatial resolution, such as spatially continuous digital elevation models of differencing techniques or seismic sensors, is advised. Overall, the measurement approach using new agricultural sensors has several unique advantages and disadvantages and can be a good tool for the monitoring of river bank erosion and could lead to new insights.
... DOC concentrations in these lakes depend on multiple interacting environmental factors (e.g., permafrost extent, topography, vegetation cover; Stolpmann et al. 2021), hydrological and morphometric factors (e.g., lake water retention time, drainage ratio, precipitation patterns; Houle et al. 2020) as well as anthropogenic factors (e.g., landscape utilization, recovery from acid deposition; Meyer-Jacob et al. 2015;Meyer-Jacob et al. 2019). The shallow lakes that dominate this region are facing unique challenges as a result of anthropogenic climate change (Bouchard et al. 2017). Paleolimnological studies of thermokarst lakes (i.e., lakes formed when thawing permafrost creates surface depressions that are filled with meltwater) have examined responses to warming using many approaches. ...
Covering 55% of Canada’s total surface area and stretching from coast to coast to coast, the Canadian boreal zone is crucial to the nation’s economic and ecological integrity. Although often viewed as relatively underdeveloped, it is vulnerable to numerous stressors such as mining, forestry, and anthropogenic climate change. Natural archives preserved in lake sediments can provide key insights by quantifying pre-disturbance conditions (pre-1850 CE) and the nature, magnitude, direction, and speed of environmental change induced by anthropogenic stressors over the past ∼150 years. Here, we paired a review of paleolimnological literature of the Canadian boreal zone with analyses of published sediment core data to highlight the effects of climate change, catchment disturbances, and atmospheric deposition on boreal lakes. Specifically, we conducted quantitative syntheses of two lake health indicators: elemental lead (Pb) and chlorophyll a. Segmented regressions and Mann–Kendall trend analysis revealed a generally increasing trend in elemental Pb across the boreal zone until ∼1970 CE, followed by a generally decreasing trend to the present. Snapshot comparisons of sedimentary chlorophyll a from recent and pre-industrial sediments (i.e., top-bottom sediment core design) revealed that a majority of sites have increased over time, suggesting a general enhancement in lake primary production across the boreal zone. Collectively, this body of work demonstrates that long-term sediment records offer a critical perspective on ecosystem change not accessible through routine monitoring programs. We advocate using modern datasets in tandem with paleolimnology to establish baseline conditions, measure ecosystem changes, and set meaningful management targets.
... The latter largely depends upon temperature, precipitation and local permafrost characteristics (i.e., excess ice and geomorphology). Typical thermokarst development in organic-rich Pleistocene permafrost (i.e., "Yedoma" deposits) is well described by Bouchard et al. [4]. An initial thermokarst lake (or a single polygonal pond) develops as a result of the melting of excess ground ice, generally in the form of syngenetic ice wedges (i.e., formed at the same time as sediment deposition). ...
... A gradual increase in the area of such a pond due to the erosion of the shore may lead to the formation of a large thermokarst lake. Finally, partial or complete lake drainage can result in the fourth stage: a khasyrei (drained lake) [4,5]. This makes the delta a convenient object for studying the variability of aquatic ecosystem communities during successional changes of hydrological characteristics of thermokarst water bodies [3]. ...
Global climate change might result in permafrost thaw and the formation of thermokarst landscapes that release long-term carbon stocks as greenhouse into the atmosphere, thereby initiating a positive climate feedback. These processes are mediated by biological activity, including by microbes, vascular plants and animals, whereas the role of invertebrates in thermokarst ecosystems remains poorly understood. We investigated the diversity and assemblage structures of zooplankton (mainly Copepoda, Cladocera), microbenthos (testate amoebae) and meio- (Copepoda and Cladocera) and macrozoobenthos (mollusks, crustaceans, insects and annelids) from a range of water bodies representing different stages of thermokarst lake formation in the southern part of the Lena River Delta (Central Siberia). Altogether, 206 species of testate amoeba, mollusk, crustacean, insect and annelid taxa were identified. A total of 60 species of macrozoobenthos (mainly insects) and 62 species of testate amoebae were detected in the water bodies of the Lena River Delta for the first time. The species richness of zooplankton and meio- and macrozoobenthos was greater in the large thermokarst lakes than in the polygonal ponds due to the freezing of the latter in the winter. In contrast, the species richness of protists was higher in the polygonal ponds, which was related to the habitat preferences of testate amoebae. Fish grazing strongly affected the macrobenthos assemblages but not the smaller-sized organisms. Water acidity and temperature were the main environmental drivers of the assemblage structure of testate amoeba and microcrustacean. The species structure of the macroinvertebrate assemblages was significantly explained by water acidity, permafrost depth and size of the water area. It means that small size organisms with their short generation times are sensitive to more dynamic factors such as temperature and may serve as indicators of ecosystem changes due to global climate warming. In contrast, large size organisms are affected by driven factors that appear during thermokarst lakes formation and permafrost degradation.
... The warming climate has triggered permafrost degradation with a variety of consequences for the landscape (Biskaborn et al., 2019), including top-down thaw, increasing active layer over long term, thermo-erosion along coasts, rivers, and lake shores, rapid thawing associated with thermokarst processes (Strauss et al., 2017;Turetsky et al., 2020) and significant land subsidence (Anders et al., 2020;Antonova et al., 2018). Thermokarst develops in the lowland areas of ice-rich permafrost, and typically results in formation of thermokarst ponds or lakes (Bouchard et al., 2016) and reassembly of permafrost (Ernakovich et al., 2022). Thermokarst landscapes are estimated to cover approximately 20-40% of permafrost regions (Olefeldt et al., 2016;Strauss et al., 2017). ...
Thermokarst lagoons represent the transition state from a freshwater lacustrine to a marine environment, and receive little attention regarding their role for greenhouse gas production and release in Arctic permafrost landscapes. We studied the fate of methane (CH4 ) in sediments of a thermokarst lagoon in comparison to two thermokarst lakes on the Bykovsky Peninsula in northeastern Siberia through the analysis of sediment CH4 concentrations and isotopic signature, methane-cycling microbial taxa, sediment geochemistry, lipid biomarkers, and network analysis. We assessed how differences in geochemistry between thermokarst lakes and thermokarst lagoons, caused by the infiltration of sulfate-rich marine water, altered the microbial methane cycling community. Anaerobic sulfate-reducing ANME-2a/2b methanotrophs dominated the sulfate-rich sediments of the lagoon despite its known seasonal alternation between brackish and freshwater inflow and low sulfate concentrations compared to the usual marine ANME habitat. Non-competitive methylotrophic methanogens dominated the methanogenic community of the lakes and the lagoon, independent of differences in porewater chemistry and depth. This potentially contributed to the high CH4 concentrations observed in all sulfate-poor sediments. CH4 concentrations in the freshwater-influenced sediments averaged 1.34±0.98 μmol g-1 , with highly depleted δ13 C-CH4 values ranging from -89‰ to -70‰. In contrast, the sulfate-affected upper 300 cm of the lagoon exhibited low average CH4 concentrations of 0.011±0.005 μmol g-1 with comparatively enriched δ13 C-CH4 values of -54‰ to -37‰ pointing to substantial methane oxidation. Our study shows that lagoon formation specifically supports methane oxidizers and methane oxidation through changes in pore water chemistry, especially sulfate, while methanogens are similar to lake conditions.
