Variable respiration rates of incubated permafrost soil extracts from the Kolyma River lowlands, north-east Siberia

Heslop, Joanne; Chandra, Sudeep; Sobzcak, William V.; Davydov, S.; Davydova, A. I.; Spektor, Valentin V.; Anthony, K. M. Walter

doi:10.1080/17518369.2017.1305157

Cited by 5 publications

(3 citation statements)

References 62 publications

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“…Lower δ 13 C values of phytoplankton have also been observed in the Laptev Sea (which receives strong carbon input from the Lena River) as compared to the East Siberian Sea (34). Degradation of terrestrially derived organic carbon during river transport is further supported by previous incubation studies that show a rapid loss of DOC in permafrost leachates and rivers (35–43), with highest losses of up to 53% within 9 d for DOC from Ice Complex deposits (36, 37, 44). Comparable incubation studies on the degradability of POC are urgently needed, considering the high contribution of POC to PP-C export as demonstrated in this study.…”

Section: Resultssupporting

confidence: 71%

Rivers across the Siberian Arctic unearth the patterns of carbon release from thawing permafrost

Wild

Andersson

Bröder

et al. 2019

Proc. Natl. Acad. Sci. U.S.A.

146

163

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Climate warming is expected to mobilize northern permafrost and peat organic carbon (PP-C), yet magnitudes and system specifics of even current releases are poorly constrained. While part of the PP-C will degrade at point of thaw to CO2 and CH4 to directly amplify global warming, another part will enter the fluvial network, potentially providing a window to observe large-scale PP-C remobilization patterns. Here, we employ a decade-long, high-temporal resolution record of 14C in dissolved and particulate organic carbon (DOC and POC, respectively) to deconvolute PP-C release in the large drainage basins of rivers across Siberia: Ob, Yenisey, Lena, and Kolyma. The 14C-constrained estimate of export specifically from PP-C corresponds to only 17 ± 8% of total fluvial organic carbon and serves as a benchmark for monitoring changes to fluvial PP-C remobilization in a warming Arctic. Whereas DOC was dominated by recent organic carbon and poorly traced PP-C (12 ± 8%), POC carried a much stronger signature of PP-C (63 ± 10%) and represents the best window to detect spatial and temporal dynamics of PP-C release. Distinct seasonal patterns suggest that while DOC primarily stems from gradual leaching of surface soils, POC reflects abrupt collapse of deeper deposits. Higher dissolved PP-C export by Ob and Yenisey aligns with discontinuous permafrost that facilitates leaching, whereas higher particulate PP-C export by Lena and Kolyma likely echoes the thermokarst-induced collapse of Pleistocene deposits. Quantitative 14C-based fingerprinting of fluvial organic carbon thus provides an opportunity to elucidate large-scale dynamics of PP-C remobilization in response to Arctic warming.

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Section: Resultssupporting

confidence: 71%

Rivers across the Siberian Arctic unearth the patterns of carbon release from thawing permafrost

Wild

Andersson

Bröder

et al. 2019

Proc. Natl. Acad. Sci. U.S.A.

146

163

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“…In the current understanding of Arctic carbon cycles, coastal erosion is considered to play a modest role in the transfer of OC from land to the Arctic Ocean (McGuire et al, 2009;Stein and Macdonald, 2004;Macdonald et al, 2015). Recent studies on abrupt permafrost erosion on land, however, suggest that OC is already fundamentally altered upon permafrost thaw, erosion and transport in aquatic systems on land, during which greenhouse gases (GHGs) can be released to the atmosphere Mann et al, 2015;Spencer et al, 2015;Heslop et al, 2017). During these erosional processes, the composition of OC is altered substantially with a substantial fraction potentially transformed into carbon dioxide (CO 2 ) and methane (CH 4 ), depending on oxygen availability (Vonk et al, 2012;Semiletov et al, 2016;Tanski et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Permafrost Carbon and CO2 Pathways Differ at Contrasting Coastal Erosion Sites in the Canadian Arctic

et al. 2021

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Warming air and sea temperatures, longer open-water seasons and sea-level rise collectively promote the erosion of permafrost coasts in the Arctic, which profoundly impacts organic matter pathways. Although estimates on organic carbon (OC) fluxes from erosion exist for some parts of the Arctic, little is known about how much OC is transformed into greenhouse gases (GHGs). In this study we investigated two different coastal erosion scenarios on Qikiqtaruk – Herschel Island (Canada) and estimate the potential for GHG formation. We distinguished between a delayed release represented by mud debris draining a coastal thermoerosional feature and a direct release represented by cliff debris at a low collapsing bluff. Carbon dioxide (CO2) production was measured during incubations at 4°C under aerobic conditions for two months and were modeled for four months and a full year. Our incubation results show that mud debris and cliff debris lost a considerable amount of OC as CO2 (2.5 ± 0.2 and 1.6 ± 0.3% of OC, respectively). Although relative OC losses were highest in mineral mud debris, higher initial OC content and fresh organic matter in cliff debris resulted in a ∼three times higher cumulative CO2 release (4.0 ± 0.9 compared to 1.4 ± 0.1 mg CO2 gdw–1), which was further increased by the addition of seawater. After four months, modeled OC losses were 4.9 ± 0.1 and 3.2 ± 0.3% in set-ups without seawater and 14.3 ± 0.1 and 7.3 ± 0.8% in set-ups with seawater. The results indicate that a delayed release may support substantial cycling of OC at relatively low CO2 production rates during long transit times onshore during the Arctic warm season. By contrast, direct erosion may result in a single CO2 pulse and less substantial OC cycling onshore as transfer times are short. Once eroded sediments are deposited in the nearshore, highest OC losses can be expected. We conclude that the release of CO2 from eroding permafrost coasts varies considerably between erosion types and residence time onshore. We emphasize the importance of a more comprehensive understanding of OC degradation during the coastal erosion process to improve thawed carbon trajectories and models.

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“…Biolability of permafrost derived DOM has been observed to be dependent upon the composition of organic matter 6,18,24,25 and lake ontogeny, 26 and yedoma organic matter may be especially labile. 6,11,27 For example, Heslop et al 6 observed that increased biolability along four depths of yedoma lake sediment was due to a higher abundance of reduced and saturated organic compounds.…”

Section: Introductionmentioning

confidence: 99%

Composition and photo-reactivity of organic matter from permafrost soils and surface waters in interior Alaska

Gagne

Ewers

Murphy

et al. 2020

Environ. Sci.: Processes Impacts

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Variable respiration rates of incubated permafrost soil extracts from the Kolyma River lowlands, north-east Siberia

Cited by 5 publications

References 62 publications

Rivers across the Siberian Arctic unearth the patterns of carbon release from thawing permafrost

Rivers across the Siberian Arctic unearth the patterns of carbon release from thawing permafrost

Permafrost Carbon and CO2 Pathways Differ at Contrasting Coastal Erosion Sites in the Canadian Arctic

Composition and photo-reactivity of organic matter from permafrost soils and surface waters in interior Alaska

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