Carbon emission from thermokarst lakes in NE European tundra

Abstract

Emission of greenhouse gases (GHGs) from inland waters is recognized as highly important and an understudied part of the terrestrial carbon (C) biogeochemical cycle. These emissions are still poorly quantified in subarctic regions that contain vast amounts of surface C in permafrost peatlands. This is especially true in NE European peatlands, located within sporadic to discontinuous permafrost zones which are highly vulnerable to thaw. Initial measurements of C emissions from lentic waters of the Bolshezemelskaya Tundra (BZT; 200,000 km 2) demonstrated sizable CO 2 and CH 4 concentrations and fluxes to the atmosphere in 98 depressions, thaw ponds, and thermokarst lakes ranging from 0.5 × 10 6 to 5 × 10 6 m 2 in size. CO 2 fluxes decreased by an order of magnitude as waterbody size increased by > 3 orders of magnitude while CH 4 fluxes showed large variability unrelated to lake size. By using a combination of Landsat-8 and GeoEye-1 images, we determined lakes cover 4% of BZT and thus calculated overall C emissions from lentic waters to be 3.8 AE 0.65 Tg C yr −1 (99% C-CO 2 , 1% C-CH 4), which is two times higher than the lateral riverine export. Large lakes dominated GHG emissions whereas small thaw ponds had a minor contribution to overall water surface area and GHG emissions. These data suggest that, if permafrost thaw in NE Europe results in disappearance of large thermokarst lakes and formation of new small thaw ponds and depressions, GHG emissions from lentic waters in this region may decrease.

Identifying Drivers Behind Spatial Variability of Methane Concentrations in East Siberian Ponds

“…As previous studies (DelSontro et al, 2018;Zabelina et al, 2020) suggest, we find that pond area alone is not sufficient to explain variability in methane concentrations. Yet, the observed trend is in agreement with prior studies (Juutinen et al, 2009;Wik et al, 2016), and the relation between pond size and methane concentrations is very similar to the estimate by Polishchuk et al (2018)-their regression line follows log([CH 4 ]) = −0.258 • log(area) + 0.635.…”

Sentinel‐Based Inventory of Thermokarst Lakes and Ponds Across Permafrost Landscapes on the Qinghai‐Tibet Plateau

“…One of the most obvious characteristics of thermokarst landforms is the formation of thaw lakes (Anthony et al, 2018;Zabelina et al, 2021). Despite their small waterbody size, these lakes play an important role both within the natural environment and socioeconomically.…”

“…Recently, several studies have applied satellite remote sensing to the mapping and monitoring of thaw lakes in Arctic permafrost regions. For example, multisource remote sensing has been used to compile thaw lake inventories in various regions, such as western Alaska (Lindgren et al, 2021), NE European peatlands (Zabelina et al, 2021), the vast western Siberian lowland (Polishchuk et al, 2018), and even circum-Arctic and subarctic permafrost areas (Muster et al, 2017;Nitze et al, 2018). In particular, Landsat imagery was most frequently used due to its wide coverage, continuous, and free accessibility (Wang et al, 2020).…”

Element cycling and aquatic function in a changing Arctic

“…Within this special issue, most studies focus on current or potential climate change effects, but the uncertainty in scaling precludes an accurate determination as to how those effects would translate quantitatively into a feedback. The best example of a feedback prediction might be the study of Zabelina et al (2021), which concludes that small ponds emit smaller areal fluxes of greenhouse gasses than large thermokarst lakes, and that if large lakes become less dominant with permafrost thaw (Smith et al 2005), the overall effect will be a net negative feedback.…”

“…In this special issue, several authors reinforce this importance of landscape, lake origin, and lake evolution for lake function. For example, Zabelina et al (2021) show that CO 2 emissions from Bolshezemelskaya (northeastern European) tundra lakes are more strongly determined by lake area than any other parameter, with emissions increasing by over an order of magnitude from large to small lakes. Hughes-Allen et al (2021) show that greenhouse gas emissions from thermokarst-origin lakes in Central Yakutia (Russia) are inextricably linked to lake age, with recent thermokarst lakes acting as strong CO 2 sources throughout all seasons, whereas hydrologically closed alas lakes (formed via thermokarst processes during the early Holocene warm interval) act as CO 2 sinks during spring and fall, and much more modest CO 2 sources in winter.…”