Abstract
AbstractEmission 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 km2) demonstrated sizable CO2 and CH4 concentrations and fluxes to the atmosphere in 98 depressions, thaw ponds, and thermokarst lakes ranging from 0.5 × 106 to 5 × 106 m2 in size. CO2 fluxes decreased by an order of magnitude as waterbody size increased by > 3 orders of magnitude while CH4 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 ± 0.65 Tg C yr−1 (99% C‐CO2, 1% C‐CH4), 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.
Highlights
Arctic and subarctic lakes emit sizeable amounts of greenhouse gases (GHGs) to the atmosphere (Tranvik et al 2009; Kosten et al 2010)
Among large territories of frozen peatbogs accessible all year round for sampling, the Bolshezemelskaya Tundra (BZT) of northeastern Europe is especially interesting as it contains a vast amount of thermokarst lakes (Goldina 1972; Davydova et al 1994), combines isolated, sporadic and discontinuous permafrost zones, and exhibits a generally milder climate and with a higher terrestrial biome productivity compared to western Siberia (Zamolodchikov and Karelin 2001)
We exclusively considered lake size as the main controlling parameter on GHG, dissolved organic carbon (DOC), and dissolved inorganic carbon (DIC) concentration because temporal and spatial variations of concentrations and fluxes were smaller than variations due to lake size
Summary
Arctic and subarctic lakes emit sizeable amounts of greenhouse gases (GHGs) to the atmosphere (Tranvik et al 2009; Kosten et al 2010). Bartosiewicz et al 2016), numerous works have measured carbon emissions from inland waters in circumpolar territories (Rautio et al 2011; Langer et al 2015; Wik et al 2016). In these regions, abundant thermokarst lakes are formed via thawing of frozen organic or mineral soils (Shirokova et al 2013; Sjöberg et al 2013; Bouchard et al 2017). Geographical coverage of available GHG measurements (citations in the left panel) in thermokarst lakes is shown on the global permafrost map. There is recent interest in the BZT as over past decades lakes in this territory exhibited sizeable increases in summer temperature and pCO2, presumably due to enhanced bacterial respiration of allochthonous dissolved organic matter (DOM) from thawing permafrost (Drake et al 2019)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
