scholarly journals Spatial and Seasonal Variations of C, Nutrient, and Metal Concentration in Thermokarst Lakes of Western Siberia Across a Permafrost Gradient

Water ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1830 ◽  
Author(s):  
Rinat M. Manasypov ◽  
Artem G. Lim ◽  
Ivan V. Kriсkov ◽  
Liudmila S. Shirokova ◽  
Sergey N. Vorobyev ◽  
...  
Keyword(s):  
Climate Warming ◽  
Seasonal Variations ◽  
Western Siberia ◽  
Dissolved Inorganic Carbon ◽  
Permafrost Zone ◽  
Large Lakes ◽  
Thermokarst Lakes ◽  
Permafrost Thaw ◽  
Spatial Coverage ◽  
Continuous Permafrost

Thermokarst lakes and ponds formed due to thawing of frozen peat in high-latitude lowlands are very dynamic and environmentally important aquatic systems that play a key role in controlling C emission to atmosphere and organic carbon (OC), nutrient, and metal lateral export to rivers and streams. However, despite the importance of thermokarst lakes in assessing biogeochemical functioning of permafrost peatlands in response to climate warming and permafrost thaw, spatial (lake size, permafrost zone) and temporal (seasonal) variations in thermokarst lake hydrochemistry remain very poorly studied. Here, we used unprecedented spatial coverage (isolated, sporadic, discontinuous, and continuous permafrost zone of the western Siberia Lowland) of 67 lakes ranging in size from 102 to 105 m2 for sampling during three main hydrological periods of the year: spring flood, summer baseflow, and autumn time before ice-on. We demonstrate a systematic, all-season decrease in the concentration of dissolved OC (DOC) and an increase in SO4, N-NO3, and some metal (Mn, Co, Cu, Mo, Sr, U, Sb) concentration with an increase in lake surface area, depending on the type of the permafrost zone. These features are interpreted as a combination of (i) OC and organically bound metal leaching from peat at the lake shore, via abrasion and delivery of these compounds by suprapermafrost flow, and (ii) deep groundwater feeding of large lakes (especially visible in the continuous permafrost zone). Analyses of lake water chemical composition across the permafrost gradient allowed a first-order empirical prediction of lake hydrochemical changes in the case of climate warming and permafrost thaw, employing a substituting space for time scenario. The permafrost boundary shift northward may decrease the concentrations and pools of dissolved inorganic carbon (DIC), Li, B, Mg, K, Ca, Sr, Ba, Ni, Cu, As, Rb, Mo, Sr, Y, Zr, rare Earth elements (REEs), Th, and U by a factor of 2–5 in the continuous permafrost zone, but increase the concentrations of CH4, DOC, NH4, Cd, Sb, and Pb by a factor of 2–3. In contrast, the shift of the sporadic to isolated zone may produce a 2–5-fold decrease in CH4, DOC, NH4, Al, P, Ti, Cr, Ni, Ga, Zr, Nb, Cs, REEs, Hf, Th, and U. The exact magnitude of this response will, however, be strongly seasonally dependent, with the largest effects observable during baseflow seasons.

scholarly journals Dissolved organic carbon and major and trace elements in peat porewater of sporadic, discontinuous, and continuous permafrost zones of western Siberia

2017 ◽  
Vol 14 (14) ◽  
pp. 3561-3584 ◽  
Author(s):  
Tatiana V. Raudina ◽  
Sergey V. Loiko ◽  
Artyom G. Lim ◽  
Ivan V. Krickov ◽  
Liudmila S. Shirokova ◽  
...  
Keyword(s):  
Trace Elements ◽  
Organic Carbon ◽  
Western Siberia ◽  
Peat Soil ◽  
Major And Trace Elements ◽  
Permafrost Zone ◽  
Discontinuous Permafrost ◽  
Latitudinal Transect ◽  
Soil Solutions ◽  
Continuous Permafrost

Abstract. Mobilization of dissolved organic carbon (DOC) and related trace elements (TEs) from the frozen peat to surface waters in the permafrost zone is expected to enhance under ongoing permafrost thaw and active layer thickness (ALT) deepening in high-latitude regions. The interstitial soil solutions are efficient tracers of ongoing bio-geochemical processes in the critical zone and can help to decipher the intensity of carbon and metals migration from the soil to the rivers and further to the ocean. To this end, we collected, across a 640 km latitudinal transect of the sporadic to continuous permafrost zone of western Siberia peatlands, soil porewaters from 30 cm depth using suction cups and we analyzed DOC, dissolved inorganic carbon (DIC), and 40 major elements and TEs in 0.45 µm filtered fraction of 80 soil porewaters. Despite an expected decrease in the intensity of DOC and TE mobilization from the soil and vegetation litter to the interstitial fluids with the increase in the permafrost coverage and a decrease in the annual temperature and ALT, the DOC and many major and trace elements did not exhibit any distinct decrease in concentration along the latitudinal transect from 62.2 to 67.4° N. The DOC demonstrated a maximum of concentration at 66° N, on the border of the discontinuous/continuous permafrost zone, whereas the DOC concentration in peat soil solutions from the continuous permafrost zone was equal to or higher than that in the sporadic/discontinuous permafrost zone. Moreover, a number of major (Ca, Mg) and trace (Al, Ti, Sr, Ga, rare earth elements (REEs), Zr, Hf, Th) elements exhibited an increasing, not decreasing, northward concentration trend. We hypothesize that the effects of temperature and thickness of the ALT are of secondary importance relative to the leaching capacity of peat, which is in turn controlled by the water saturation of the peat core. The water residence time in peat pores also plays a role in enriching the fluids in some elements: the DOC, V, Cu, Pb, REEs, and Th were a factor of 1.5 to 2.0 higher in mounds relative to hollows. As such, it is possible that the time of reaction between the peat and downward infiltrating waters essentially controls the degree of peat porewater enrichments in DOC and other solutes. A 2° northward shift in the position of the permafrost boundaries may bring about a factor of 1.3 ± 0.2 decrease in Ca, Mg, Sr, Al, Fe, Ti, Mn, Ni, Co, V, Zr, Hf, Th, and REE porewater concentration in continuous and discontinuous permafrost zones, and a possible decrease in DOC, specific ultraviolet absorbency (SUVA), Ca, Mg, Fe, and Sr will not exceed 20 % of their current values. The projected increase in ALT and vegetation density, northward migration of the permafrost boundary, or the change of hydrological regime is unlikely to modify chemical composition of peat porewater fluids larger than their natural variations within different micro-landscapes, i.e., within a factor of 2. The decrease in DOC and metal delivery to small rivers and lakes by peat soil leachate may also decrease the overall export of dissolved components from the continuous permafrost zone to the Arctic Ocean. This challenges the current paradigm on the increase in DOC export from the land to the ocean under climate warming in high latitudes.

Biogeochemistry of macrophytes, sediments and porewaters in thermokarst lakes of western Siberia in the discontinuous and continuous permafrost zone

2020 ◽  
Author(s):  
Rinat Manasypov ◽  
Oleg Pokrovsky ◽  
Liudmila Shirokova
Keyword(s):  
Trace Elements ◽  
Lake Sediments ◽  
Aquatic Plants ◽  
Lake Water ◽  
Western Siberia ◽  
The Arctic ◽  
Formation Mechanisms ◽  
Thermokarst Lakes ◽  
Continuous Permafrost ◽  
Thaw Lakes

<p>Despite high importance of macrophytes in shallow thaw lakes for control of major and trace nutrients in lake water, the chemical composition of different aquatic plants and trace element (TE) partitioning between macrophytes and lake water and sediments in the permafrost regions remain totally unknown. Here we sampled dominant macrophytes of thermokarst (thaw) lakes of discontinuous and continuous permafrost zones in Western Siberia Lowland (WSL) and we measured major and trace elements in plant biomass, lake water, lake sediments and sediment porewater. All 6 studies plants (Hippuris vulgaris L., Glyceria maxima (Hartm.) Holmb., Comarum palustre L., Ranunculus spitzbergensis Hadac, Carex aquatilis Wahlenb s. str., Menyanthes trifoliata L.), sizably accumulate macronutrients (Na, Mg, Ca), micronutrients (B, Mo, Nu, Cu, Zn, Co) and toxicants (As, Cd) relative to lake sediments. The accumulation of other trace elements including rare earth elements (REE) in macrophytes relative to pore waters and sediments was strongly species-specific. Under climate warmings scenario and the propagation of southern species northward, the accumulation of trace metals in aquatic plants of thermokarst lakes will produce preferential uptake of Cd, Pb, Ba from thermokarst lake water and sediments by the biomass of aquatic macrophytes. This may eventually diminish the transport of metal micronutrients from lakes to rivers and further to the Arctic Ocean.</p><p>Support from the RSF (RNF) grant 19-77-00073 “Experimental modeling of the formation mechanisms for elemental composition of water in thermokarst lakes of Western Siberia: vegetation effect”.</p>

scholarly journals Stability and biodegradability of organic matter from Arctic soils of Western Siberia: insights from <sup>13</sup>C-NMR spectroscopy and elemental analysis

Solid Earth ◽  
2016 ◽  
Vol 7 (1) ◽  
pp. 153-165 ◽  
Author(s):  
E. Ejarque ◽  
E. Abakumov
Keyword(s):  
Organic Matter ◽  
Nmr Spectroscopy ◽  
Climate Warming ◽  
Western Siberia ◽  
Total Carbon ◽  
The Arctic ◽  
Total Carbon Content ◽  
Ambient Temperatures ◽  
Arctic Soils ◽  
Spatial Coverage

Abstract. Arctic soils contain large amounts of organic matter which, globally, exceed the amount of carbon stored in vegetation biomass and in the atmosphere. Recent studies emphasise the potential sensitivity for this soil organic matter (SOM) to be mineralised when faced with increasing ambient temperatures. In order to better refine the predictions about the response of SOM to climate warming, there is a need to increase the spatial coverage of empirical data on SOM quantity and quality in the Arctic area. This study provides, for the first time, a characterisation of SOM from the Gydan Peninsula in the Yamal Region, Western Siberia, Russia. On the one hand, soil humic acids and their humification state were characterised by measuring the elemental composition and diversity of functional groups using solid-state 13C-nuclear magnetic resonance (NMR) spectroscopy. Also, the total mineralisable carbon was measured. Our results indicate that there is a predominance of aliphatic carbon structures, with a minimal variation of their functional-group composition both regionally and within soil depth. This vertical homogeneity and low level of aromaticity reflects the accumulation in soil of lowly decomposed organic matter due to cold temperatures. Mineralisation rates were found to be independent of SOM quality, and to be mainly explained solely by the total carbon content. Overall, our results provide further evidence on the sensitivity that the soils of Western Siberia may have to increasing ambient temperatures and highlight the important role that this region can play in the global carbon balance under the effects of climate warming.

scholarly journals Dissolved organic carbon, major and trace element in peat pore water of sporadic, discontinuous and continuous permafrost zone of Western Siberia

2017 ◽  
Author(s):  
Tatiana V. Raudina ◽  
Sergey V. Loiko ◽  
Artyom Lim ◽  
Ivan V. Krickov ◽  
Liudmila S. Shirokova ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Pore Water ◽  
Western Siberia ◽  
Permafrost Zone ◽  
Discontinuous Permafrost ◽  
Peat Pore Water ◽  
Latitudinal Transect ◽  
Soil Solutions ◽  
Continuous Permafrost

Abstract. Mobilization of dissolved organic carbon (DOC) and related trace elements (TE) from the frozen peat to surface waters in the permafrost zone is one the major consequence of on-going permafrost thaw and active layer thickness (ALT) rise in high latitude regions. The interstitial soil solutions are efficient tracers of on-going bio-geochemical processes in the critical zone and can help to decipher the intensity of carbon and metals migration from the soil to the rivers and further to the ocean. To this end, we collected, across a 640 km latitudinal transect of sporadic to continuous permafrost zone of western Siberia peatlands, soil porewaters from 30 cm depth using suction cups and we analyzed DOC, DIC and 40 major and TE in 0.45 µm filtered fraction of 80 soil porewaters. Despite an expected decrease of the intensity of DOC and TE mobilization from the soil and vegetation litter to the interstitial fluids with the increase of the permafrost coverage, decrease in the annual temperature and ALT, the DOC and many major and trace element did not exhibit any distinct decrease in concentration along the latitudinal transect from 62.2° N to 67.4° N. The DOC demonstrated a maximum of concentration at 66° N, on the border of discontinuous/continuous permafrost zone, whereas the DOC concentration in peat soil solutions from continuous permafrost zone was equal or higher than that in sporadic/discontinuous permafrost zone. Moreover, a number of major (Ca, Mg) and trace (Al, Ti, Sr, Ga, REEs, Zr, Hf, Th) elements exhibited an increasing, not decreasing northward concentration trend. We hypothesize that the effect of temperature and thickness of the ALT are of secondary importance relative to the leaching capacity of peat which is in turn controlled by the water saturation of the peat core. The water residence time in peat pores also plays a role in enriching the fluids in some elements: the DOC, V, Cu, Pb, REE, Th were a factor of 1.5 to 2.0 higher in mounds relative to hollows. As such, it is possible that the time of reaction between the peat and downward infiltrating waters essentially controls the degree of peat pore-water enrichments in DOC and other solutes. A two-degree northward shift in the position of the permafrost boundaries may bring about a factor of 1.3 decrease in Ca, Mg, Sr, Al, Fe, Ti, Mn, Ni, Co, V, Zr, Hf, Th and REE porewater concentration in continuous and discontinuous permafrost zones, and a possible decrease in DOC, SUVA, Ca, Mg, Fe and Sr will not exceed 20 % of their actual values. The projected increase of ALT and vegetation density, northward migration of the permafrost boundary, or the change of hydrological regime are unlikely to modify chemical composition of peat pore water fluids larger than their natural variations within different micro-landscapes, i.e., within a factor of 2.

scholarly journals The trajectory of landcover change in peatland complexes with discontinuous permafrost, northwestern Canada

2020 ◽  
Author(s):  
Olivia Carpino ◽  
Kristine Haynes ◽  
Ryan Connon ◽  
James Craig ◽  
Élise Devoie ◽  
...  
Keyword(s):  
Climate Warming ◽  
Permafrost Zone ◽  
High Rate ◽  
Permafrost Thaw ◽  
Landcover Change ◽  
Plateau Wetland ◽  
Discontinuous Permafrost ◽  
Local Mean ◽  
Time Substitution ◽  
Rapid Transformation

Abstract. The discontinuous permafrost zone is undergoing rapid transformation as a result of unprecedented permafrost thaw brought on by circumpolar climate warming. Rapid climate warming over recent decades has significantly decreased the area underlain by permafrost in peatland complexes. It has catalyzed extensive landscape transitions in the Taiga Plains of northwestern Canada, transforming forest-dominated landscapes to those that are wetland-dominated. The high rate and large spatial extent of this thaw-induced landcover transformation indicates that this region is particularly sensitive to warming temperatures and will continue to respond to climatic changes and landscape disturbances. This study explores the current trajectory of landcover change across a 300 000 km2 region of northwestern Canada's discontinuous permafrost zone by presenting a space-for-time substitution that capitalizes on the region's 600 km latitudinal span. To illustrate this trajectory of change we present the distribution of peatland-rich environments that govern permafrost coverage in this region of the discontinuous permafrost zone. We also establish that relatively undisturbed forested plateau-wetland complexes dominate the region's higher latitudes, forest-wetland patchworks are most prevalent at the medial latitudes, and forested peatlands are increasingly present across lower latitudes, indicating not only a climatic gradient but also a landscape in transition as local mean temperatures increase. This study combines extensive geomatics data with ground-based meteorological and hydrological measurements to inform a new conceptual model of landscape evolution that accounts for the observed patterns of permafrost thaw-induced landcover change, and provides a basis for predicting future changes.

scholarly journals Permafrost coverage, watershed area and season control of dissolved carbon and major elements in western Siberian rivers

2015 ◽  
Vol 12 (13) ◽  
pp. 10621-10677 ◽  
Author(s):  
O. S. Pokrovsky ◽  
R. M. Manasypov ◽  
S. Loiko ◽  
L. S. Shirokova ◽  
I. A. Krivtzov ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Western Siberia ◽  
Biomass Productivity ◽  
Major Elements ◽  
Permafrost Zone ◽  
Spring Flood ◽  
Free Zone ◽  
Discontinuous Permafrost ◽  
Continuous Permafrost

Abstract. Analysis of dissolved organic and inorganic carbon (DOC and DIC, respectively), pH, Na, K, Ca, Mg, Cl, SO4 and Si in ~ 100 large and small rivers (< 100 to ≤ 150 000 km2) of western Siberia sampled in winter, spring, summer and autumn over a more than 1500 km latitudinal gradient allowed for establishing the main environmental factors controlling the transport of dissolved river components in this environmentally important region, comprising continuous, discontinuous, sporadic and permafrost-free zones. There was significant latitudinal trend consisting in general decrease of DOC, DIC, SO4, and major cation (Ca, Mg, Na, K) concentrations northward, reflecting the interplay between groundwater feeding (detectable mostly in the permafrost-free zone, south of 60° N) and surface flux (in the permafrost-bearing zone). The trend of inorganic components was mostly pronounced in winter and less visible in spring, whereas for DOC, the trend of concentration decrease with latitude was absent in winter, and less pronounced in the spring flood than in the summer baseflow. The latitudinal trends persisted over all river watershed sizes, from < 100 to > 10 000 km2. This suggested that in addition to groundwater feeding of the river, there was a significant role of surface and shallow subsurface flow linked to plant litter degradation and peat leaching. Environmental factors are ranked by their increasing effect on DOC, DIC, δ13CDIC, and major elements in western Siberian rivers as the following: watershed area < season < latitude. Seasonal fluxes of dissolved components did not significantly depend on the river size and as such could be calculated as a~function of watershed latitude. Unexpectedly, the DOC flux remained stable around 3 t km−2 yr−1 until 61° N, decreased two-fold in the discontinuous permafrost zone (62–66° N), and increased again to 3 t km−2 yr−1 in the continuous permafrost zone (67° N). The DIC, Mg, K and Ca followed this pattern. The total dissolved cation flux (TDS_c) ranged from 1.5 to 5.5 t km−2 yr−1, similar to that in central Siberian rivers of the continuous permafrost region. While Si concentration was almost unaffected by the latitude over all seasons, the Si flux systematically increased northward, suggesting a decreasing role of secondary mineral formation in soil and of vegetation uptake. The dominating effect of latitude cannot however be interpreted solely in terms of permafrost abundance and water flow path (deep vs. surface) but has to be considered in the context of different climate, plant biomass productivity, unfrozen peat thickness and peat chemical composition. It can be anticipated that, under climate warming in western Siberia, the maximal change will occur in small (< 1000 km2 watershed) rivers DOC, DIC and ionic composition, and this change will be mostly pronounced in summer and autumn. The wintertime concentrations and spring flood fluxes and concentrations are unlikely to be appreciably affected by the change of the active layer depth and terrestrial biomass productivity. Assuming a conservative precipitation scenario and rising temperature over next few centuries, the annual fluxes of DOC and K in the discontinuous permafrost zone may see a maximum increase by a factor of 2, whereas for DIC and Mg, this increase may achieve a factor of 3. The fluxes of Ca and TDS_c may increase by a factor of 5. At the same time, Si fluxes will either remain constant or decrease two-fold in the permafrost-bearing zone relative to the permafrost-free zone of western Siberia.

scholarly journals Thermal processes of thermokarst lakes in the continuous permafrost zone of northern Siberia – observations and modeling (Lena River Delta, Siberia)

2015 ◽  
Vol 12 (20) ◽  
pp. 5941-5965 ◽  
Author(s):  
J. Boike ◽  
C. Georgi ◽  
G. Kirilin ◽  
S. Muster ◽  
K. Abramova ◽  
...  
Keyword(s):  
Heat Flux ◽  
Water Column ◽  
Permafrost Zone ◽  
Thermal Processes ◽  
Lena River ◽  
Thermokarst Lakes ◽  
Continuous Permafrost ◽  
Lake Bottom ◽  
Break Up ◽  
Lena River Delta

Abstract. Thermokarst lakes are typical features of the northern permafrost ecosystems, and play an important role in the thermal exchange between atmosphere and subsurface. The objective of this study is to describe the main thermal processes of the lakes and to quantify the heat exchange with the underlying sediments. The thermal regimes of five lakes located within the continuous permafrost zone of northern Siberia (Lena River Delta) were investigated using hourly water temperature and water level records covering a 3-year period (2009–2012), together with bathymetric survey data. The lakes included thermokarst lakes located on Holocene river terraces that may be connected to Lena River water during spring flooding, and a thermokarst lake located on deposits of the Pleistocene Ice Complex. Lakes were covered by ice up to 2 m thick that persisted for more than 7 months of the year, from October until about mid-June. Lake-bottom temperatures increased at the start of the ice-covered period due to upward-directed heat flux from the underlying thawed sediment. Prior to ice break-up, solar radiation effectively warmed the water beneath the ice cover and induced convective mixing. Ice break-up started at the beginning of June and lasted until the middle or end of June. Mixing occurred within the entire water column from the start of ice break-up and continued during the ice-free periods, as confirmed by the Wedderburn numbers, a quantitative measure of the balance between wind mixing and stratification that is important for describing the biogeochemical cycles of lakes. The lake thermal regime was modeled numerically using the FLake model. The model demonstrated good agreement with observations with regard to the mean lake temperature, with a good reproduction of the summer stratification during the ice-free period, but poor agreement during the ice-covered period. Modeled sensitivity to lake depth demonstrated that lakes in this climatic zone with mean depths > 5 m develop continuous stratification in summer for at least 1 month. The modeled vertical heat flux across the bottom sediment tends towards an annual mean of zero, with maximum downward fluxes of about 5 W m−2 in summer and with heat released back into the water column at a rate of less than 1 W m−2 during the ice-covered period. The lakes are shown to be efficient heat absorbers and effectively distribute the heat through mixing. Monthly bottom water temperatures during the ice-free period range up to 15 °C and are therefore higher than the associated monthly air or ground temperatures in the surrounding frozen permafrost landscape. The investigated lakes remain unfrozen at depth, with mean annual lake-bottom temperatures of between 2.7 and 4 °C.

scholarly journals Size Distribution, Surface Coverage, Water, Carbon, and Metal Storage of Thermokarst Lakes in the Permafrost Zone of the Western Siberia Lowland

Water ◽  
2017 ◽  
Vol 9 (3) ◽  
pp. 228 ◽  
Author(s):  
Yury Polishchuk ◽  
Alexander Bogdanov ◽  
Vladimir Polishchuk ◽  
Rinat Manasypov ◽  
Liudmila Shirokova ◽  
...  
Keyword(s):  
Size Distribution ◽  
Western Siberia ◽  
Surface Coverage ◽  
Permafrost Zone ◽  
Thermokarst Lakes
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