Transformation of terrestrial organic matter along thermokarst-affected permafrost coasts in the Arctic

Tanski, George; Lantuit, Hugues; Ruttor, Saskia; Knoblauch, Christian; Radosavljevic, Boris; Strauß, Jens; Wolter, Juliane; Irrgang, Anna; Ramage, Justine; Fritz, Michael

doi:10.1016/j.scitotenv.2016.12.152

Cited by 54 publications

(81 citation statements)

References 103 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…High N 2 O flux in our study area is partially attributable to the relative high soil nitrogen contents (about 1.5% in the upper 50 cm soils) [ Mu et al, ], which is often associated with N 2 O flux [ Velthof et al, ]. The 61% increase in N 2 O flux from exposed patches could be due to the fact that thermokarst formation simultaneously increases biodegradable nitrogen [ Darrouzetnardi and Weintraub , ; Harms et al, ; Tanski et al, ] and creates heterogeneous redox conditions where coupled nitrification‐denitrification can occur [ Abbott and Jones , ]. Additionally, during thermokarst development, labile DOC from the thawing permafrost [ Abbott et al, ; Mu et al, ] can accelerate denitrification by serving as electron donors [ Abbott and Jones , ].…”

Section: Discussionmentioning

confidence: 99%

Permafrost collapse shifts alpine tundra to a carbon source but reduces N₂O and CH₄ release on the northern Qinghai‐Tibetan Plateau

Abbott

Zhao

et al. 2017

Geophysical Research Letters

View full text Add to dashboard Cite

Important unknowns remain about how abrupt permafrost collapse (thermokarst) affects carbon balance and greenhouse gas flux, limiting our ability to predict the magnitude and timing of the permafrost carbon feedback. We measured monthly, growing‐season fluxes of CO2, CH4, and N2O at a large thermokarst feature in alpine tundra on the northern Qinghai‐Tibetan Plateau (QTP). Thermokarst formation disrupted plant growth and soil hydrology, shifting the ecosystem from a growing‐season carbon sink to a weak source but decreasing feature level CH4 and N2O flux. Temperature‐corrected ecosystem respiration from decomposing permafrost soil was 2.7 to 9.5‐fold higher than in similar features from Arctic and Boreal regions, suggesting that warmer and dryer conditions on the northern QTP could accelerate carbon decomposition following permafrost collapse. N2O flux was similar to the highest values reported for Arctic ecosystems and was 60% higher from exposed mineral soil on the feature floor, confirming Arctic observations of coupled nitrification and denitrification in collapsed soils. Q10 values for respiration were typically over 4, suggesting high‐temperature sensitivity of thawed carbon. Taken together, these results suggest that QTP permafrost carbon in alpine tundra is highly vulnerable to mineralization following thaw, and that N2O production could be an important noncarbon permafrost climate feedback. Permafrost collapse altered soil hydrology, shifting the ecosystem from a carbon sink to carbon source but decreasing CH4 and N2O flux. Little to no vegetation recovery after stabilization suggests potentially large net carbon losses. High N2O flux compared to Arctic and Boreal systems suggests noncarbon permafrost climate feedback.

show abstract

Section: Discussionmentioning

confidence: 99%

Permafrost collapse shifts alpine tundra to a carbon source but reduces N₂O and CH₄ release on the northern Qinghai‐Tibetan Plateau

Abbott

Zhao

et al. 2017

Geophysical Research Letters

View full text Add to dashboard Cite

show abstract

“…Of these, thermokarst has the potential to rapidly expose significant quantities of previously frozen soils to biological and chemical processing (Abbott et al, 2014(Abbott et al, , 2015Malone et al, 2013;Tanski et al, 2017). One of the most conspicuous manifestations of thermokarst is the retrogressive thaw slump (RTS; Fig.…”

Section: Introductionmentioning

confidence: 99%

Retrogressive thaw slumps temper dissolved organic carbon delivery to streams of the Peel Plateau, NWT, Canada

2017

View full text Add to dashboard Cite

Abstract. In Siberia and Alaska, permafrost thaw has been associated with significant increases in the delivery of dissolved organic carbon (DOC) to recipient stream ecosystems. Here, we examine the effect of retrogressive thaw slumps (RTSs) on DOC concentration and transport, using data from eight RTS features on the Peel Plateau, NWT, Canada. Like extensive regions of northwestern Canada, the Peel Plateau is comprised of thick, ice-rich tills that were deposited at the margins of the Laurentide Ice Sheet. RTS features are now widespread in this region, with headwall exposures up to 30 m high and total disturbed areas often exceeding 20 ha. We find that intensive slumping on the Peel Plateau is universally associated with decreasing DOC concentrations downstream of slumps, even though the composition of slump-derived dissolved organic matter (DOM; assessed using specific UV absorbance and slope ratios) is similar to permafrost-derived DOM from other regions. Comparisons of upstream and downstream DOC flux relative to fluxes of total suspended solids suggest that the substantial fine-grained sediments released by RTS features may sequester DOC. Runoff obtained directly from slump rill water, above entry into recipient streams, indicates that the deepest RTS features, which thaw the greatest extent of buried, Pleistocene-aged glacial tills, release low-concentration DOC when compared to paired upstream, undisturbed locations, while shallower features, with exposures that are more limited to a relict Holocene active layer, have within-slump DOC concentrations more similar to upstream sites. Finally, fine-scale work at a single RTS site indicates that temperature and precipitation serve as primary environmental controls on above-slump and below-slump DOC flux, but it also shows that the relationship between climatic parameters and DOC flux is complex for these dynamic thermokarst features. These results demonstrate that we should expect clear variation in thermokarst-associated DOC mobilization across Arctic regions. However, they also show that within-region variation in thermokarst intensity and landscape composition is critical for determining the biogeochemical response. Geological and climate legacy shape the physical and chemical composition of permafrost and thermokarst potential. As such, these factors must be considered in predictions of land-to-water carbon mobilization in a warming Arctic.

show abstract

“…Hence, OC is mobilized in RTSs prior to its release to the ocean, which modifies the amount of OC available to the coastal ecosystem (Tanski et al, 2017;Cassidy et al, 2016;Pizano et al, 2014). Tanski et al (2017) show that SOC and DOC decrease by 77 and 55 %, respectively, before reaching the nearshore zone. Abbott and Jones (2015) describe similar processes for RTSs in upland areas: after RTSs develop, 51 % of organic-layer SOC and 21 kg m −2 of mineral-layer SOC is removed.…”

Section: Impact Of Rtss On the Coastal Ecosystemmentioning

confidence: 98%

“…However, a fraction of this material and OC remains in the slump floor for several years (Tanski et al, 2017;Obu et al, 2016) where it degrades and is mineralized by microorganisms. Hence, OC is mobilized in RTSs prior to its release to the ocean, which modifies the amount of OC available to the coastal ecosystem (Tanski et al, 2017;Cassidy et al, 2016;Pizano et al, 2014). Tanski et al (2017) show that SOC and DOC decrease by 77 and 55 %, respectively, before reaching the nearshore zone.…”

Section: Impact Of Rtss On the Coastal Ecosystemmentioning

confidence: 99%

“…Following headwall erosion, water transports melted ground ice and most sediments to the nearshore zone. Without enough viscous flow, the remaining part of the sediments accumulates and settles on the RTS floor, as indicated by higher bulk densities in samples from RTS floors (Tanski et al, 2017;Lantuit et al, 2012a). The OC in the sediments is released to the atmosphere as CO 2 (Cassidy et al, 2016), buried in the RTS floor, or transported to the nearshore zone (Tanski et al, 2017).…”

Section: Impact Of Rtss On the Coastal Ecosystemmentioning

confidence: 99%

See 1 more Smart Citation

Increasing coastal slump activity impacts the release of sediment and organic carbon into the Arctic Ocean

et al. 2018

Self Cite

View full text Add to dashboard Cite

Abstract. Retrogressive thaw slumps (RTSs) are among the most active thermokarst landforms in the Arctic and deliver a large amount of material to the Arctic Ocean. However, their contribution to the organic carbon (OC) budget is unknown. We provide the first estimate of the contribution of RTSs to the nearshore OC budget of the Yukon Coast, Canada, and describe the evolution of coastal RTSs between 1952 and 2011 in this area. We (1) describe the evolution of RTSs between 1952 and 2011; (2) calculate the volume of eroded material and stocks of OC mobilized through slumping, including soil organic carbon (SOC) and dissolved organic carbon (DOC); and (3) estimate the OC fluxes mobilized through slumping between 1972 and 2011. We identified RTSs using high-resolution satellite imagery from 2011 and geocoded aerial photographs from 1952 and 1972. To estimate the volume of eroded material, we applied spline interpolation on an airborne lidar dataset acquired in July 2013. We inferred the stocks of mobilized SOC and DOC from existing related literature. Our results show a 73 % increase in the number of RTSs and 14 % areal expansion between 1952 and 2011. In the study area, RTSs displaced at least 16.6 × 10 6 m 3 of material, 53 % of which was ice, and mobilized 145.9×10 6 kg of OC. Between 1972 and 2011, 49 RTSs displaced 8.6 × 10 3 m 3 yr −1 of material, adding 0.6 % to the OC flux released by coastal retreat along the Yukon Coast. Our results show that the contribution of RTSs to the nearshore OC budget is non-negligible and should be included when estimating the quantity of OC released from the Arctic coast to the ocean.

show abstract

Transformation of terrestrial organic matter along thermokarst-affected permafrost coasts in the Arctic

Cited by 54 publications

References 103 publications

Permafrost collapse shifts alpine tundra to a carbon source but reduces N₂O and CH₄ release on the northern Qinghai‐Tibetan Plateau

Permafrost collapse shifts alpine tundra to a carbon source but reduces N₂O and CH₄ release on the northern Qinghai‐Tibetan Plateau

Retrogressive thaw slumps temper dissolved organic carbon delivery to streams of the Peel Plateau, NWT, Canada

Increasing coastal slump activity impacts the release of sediment and organic carbon into the Arctic Ocean

Contact Info

Product

Resources

About

Transformation of terrestrial organic matter along thermokarst-affected permafrost coasts in the Arctic

Cited by 54 publications

References 103 publications

Permafrost collapse shifts alpine tundra to a carbon source but reduces N2O and CH4 release on the northern Qinghai‐Tibetan Plateau

Permafrost collapse shifts alpine tundra to a carbon source but reduces N2O and CH4 release on the northern Qinghai‐Tibetan Plateau

Retrogressive thaw slumps temper dissolved organic carbon delivery to streams of the Peel Plateau, NWT, Canada

Increasing coastal slump activity impacts the release of sediment and organic carbon into the Arctic Ocean

Contact Info

Product

Resources

About

Permafrost collapse shifts alpine tundra to a carbon source but reduces N₂O and CH₄ release on the northern Qinghai‐Tibetan Plateau

Permafrost collapse shifts alpine tundra to a carbon source but reduces N₂O and CH₄ release on the northern Qinghai‐Tibetan Plateau