| 1. |
- Shirokova, Liudmila S., et al.
(författare)
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Humic surface waters of frozen peat bogs (permafrost zone) are highly resistant to bio- and photodegradation
- 2019
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Ingår i: Biogeosciences. - : Nicolaus Copernicus University Press. - 1726-4170 .- 1726-4189. ; 16:12, s. 2511-2526
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Tidskriftsartikel (refereegranskat)abstract
- In contrast to the large number of studies on humic waters from permafrost-free regions and oligotrophic waters from permafrost-bearing regions, the bio- and photolability of DOM from the humic surface waters of permafrost-bearing regions has not been thoroughly evaluated. Following standardized protocol, we measured biodegradation (at low, intermediate and high temperatures) and photodegradation (at one intermediate temperature) of DOM in surface waters along the hydrological continuum (depression -> stream -> thermokarst lake -> Pechora River) within a frozen peatland in European Russia. In all systems, within the experimental resolution of 5% to 10 %, there was no bio- or photodegradation of DOM over a 1-month incubation period. It is possible that the main cause of the lack of degradation is the dominance of allochthonous refractory (soil, peat) DOM in all waters studied. However, all surface waters were supersaturated with CO2. Thus, this study suggests that, rather than bio- and photodegradation of DOM in the water column, other factors such as peat pore-water DOM processing and respiration of sediments are the main drivers of elevated pCO(2) and CO2 emission in humic boreal waters of frozen peat bogs.
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| 2. |
- Zabelina, Svetlana A., et al.
(författare)
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Carbon emission from thermokarst lakes in NE European tundra
- 2021
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Ingår i: Limnology and Oceanography. - : John Wiley & Sons. - 0024-3590 .- 1939-5590. ; 66:S1, s. S216-S230
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Tidskriftsartikel (refereegranskat)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 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.
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