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

Littlefair, Cara A.; Tank, Suzanne E.; Kokelj, Steven V.

doi:10.5194/bg-14-5487-2017

Cited by 63 publications

(98 citation statements)

References 85 publications

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“…Common geochemical controls of p CO 2 and p CH 4 were significantly affected by RTS activity. Compared to upstream, RTS runoff and downstream had significantly higher concentrations of DIC, SO 4 2– , and DIN and showed lower values of SUVA 254 and DO (Tables and ; see also Kokelj et al, ; Littlefair et al, ; Zolkos et al, ). DOC concentrations were also significantly lower downstream than upstream (Table ).…”

Section: Resultsmentioning

confidence: 95%

Thermokarst Effects on Carbon Dioxide and Methane Fluxes in Streams on the Peel Plateau (NWT, Canada)

Zolkos

Tank

Striegl³

et al. 2019

JGR Biogeosciences

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Thermokarst can rapidly mobilize vast amounts of sediment, solutes, and organic carbon previously maintained in frozen soils to inland waters. Streams provide a critical pathway for transforming these materials into carbon dioxide (CO2) and methane (CH4), yet the direct effects of thermokarst on fluvial C gas efflux from streams to the atmosphere are largely unknown. Working on the Peel Plateau in the western Canadian Arctic, we show that CO2 efflux in rill runoff thaw streams (runoff) within retrogressive thaw slumps (RTSs) was four times greater than in adjacent streams and contributed modestly but disproportionately to efflux at the landscape scale. In contrast, CH4 efflux was generally greater in adjacent streams than in RTS runoff and, overall, was within the range of values reported for other northern streams. While RTS occurrence was a primary driver of CO2 efflux, CH4 efflux was more strongly associated with conditions reflective of biological activity. Transects downstream of two RTSs revealed that CH4 consistently and rapidly degassed to the atmosphere, while elevated CO2 was sustained downstream of one RTS feature. At the watershed scale, streams adjacent to RTSs rather than runoff streams within RTSs dominated fluvial CO2 and CH4 efflux. Intensifying thermokarst activity in the western Canadian Arctic will likely amplify contributions from runoff streams in RTSs to watershed‐scale fluvial C gas efflux.

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Section: Resultsmentioning

confidence: 95%

Thermokarst Effects on Carbon Dioxide and Methane Fluxes in Streams on the Peel Plateau (NWT, Canada)

Zolkos

Tank

Striegl³

et al. 2019

JGR Biogeosciences

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“…The sub-seasonal dynamics of thermokarst are also important because they have a direct impact on the local hydrology, biogeochemistry and sediment budget (Bowden et al, 2008;Kokelj et al, 2013). In particular, the seasonal timing and magnitude of the thawinduced mobilization of organic carbon and nutrients influence their lateral transport and chemical fate, and hence the type and magnitude of greenhouse gases released (Littlefair et al, 2017;Vonk and Gustafsson, 2013).…”

Section: Introductionmentioning

confidence: 99%

Sub-seasonal thaw slump mass wasting is not consistently energy limited at the landscape scale

et al. 2018

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Abstract. Predicting future thaw slump activity requires a sound understanding of the atmospheric drivers and geomorphic controls on mass wasting across a range of timescales. On sub-seasonal timescales, sparse measurements indicate that mass wasting at active slumps is often limited by the energy available for melting ground ice, but other factors such as rainfall or the formation of an insulating veneer may also be relevant. To study the sub-seasonal drivers, we derive topographic changes from single-pass radar interferometric data acquired by the TanDEM-X satellites. The estimated elevation changes at 12 m resolution complement the commonly observed planimetric retreat rates by providing information on volume losses. Their high vertical precision (around 30 cm), frequent observations (11 days) and large coverage (5000 km 2 ) allow us to track mass wasting as drivers such as the available energy change during the summer of 2015 in two study regions. We find that thaw slumps in the Tuktoyaktuk coastlands, Canada, are not energy limited in June, as they undergo limited mass wasting (height loss of around 0 cm day −1 ) despite the ample available energy, suggesting the widespread presence of early season insulating snow or debris veneer. Later in summer, height losses generally increase (around 3 cm day −1 ), but they do so in distinct ways. For many slumps, mass wasting tracks the available energy, a temporal pattern that is also observed at coastal yedoma cliffs on the Bykovsky Peninsula, Russia. However, the other two common temporal trajectories are asynchronous with the available energy, as they track strong precipitation events or show a sudden speed-up in late August respectively. The observed temporal patterns are poorly related to slump characteristics like the headwall height. The contrasting temporal behaviour of nearby thaw slumps highlights the importance of complex local and temporally varying controls on mass wasting.

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“…Impact of retrogressive thaw slumps on DOM quality was also studied in the Subarctic Peel Plateau by Littlefair et al (2017). 25…”

Section: Downstream Patterns and Impact Of Permafrost Disturbancementioning

confidence: 99%

“…A handful of studies have investigated cDOM-DOC relationships in smaller Arctic catchments: Dvornikov et al (2018) examined cDOM characteristics in surface waters of the Yamal Peninsula and cDOM-DOC relationships were examined in studies of Subarctic catchments (Balcarczyk et al, 2009;Cory et al, 2015;Larouche et al, 2015;O'Donnell et al, 2014) and the High Arctic (Fouché et al, 2017;Wang et al, 2018). Optical parameters have also 30 been used to assess the impact of permafrost disturbance on stream geochemistry in Alaska (Abbott et al, 2014), NWT Canada (Littlefair et al, 2017) and Siberia (Spence et al, 2015). As most studies focused on downstream reaches, knowledge on the Biogeosciences Discuss., https://doi.…”

Section: Introductionmentioning

confidence: 99%

Characterizing organic matter composition in small Low and High Arctic catchments using terrestrial colored dissolved organic matter (cDOM)

Coch¹,

Juhls²,

Lamoureux³

et al. 2019

Preprint

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Climate change is an important control of carbon cycling, particularly in the Arctic. Permafrost degradation through deeper thaw and physical disturbances result in the release of carbon dioxide and methane to the atmosphere and to an increase in riverine dissolved organic matter (DOM) fluxes. Whereas riverine DOM fluxes of the large Arctic rivers are well assessed, 15knowledge is limited with regard to small catchments that cover more than 40 % of the Arctic drainage basin. Here, we use absorption measurements to characterize changes in DOM quantity and quality in a Low Arctic (Herschel Island, Yukon, Canada) and a High Arctic (Cape Bounty, Melville Island, Nunavut, Canada) setting with regard to geographical differences, impacts of permafrost degradation and rainfall events. We find that DOM quantity and quality is controlled by differences in vegetation cover and soil organic carbon content. The Low Arctic site has higher SOCC and greater abundance of plant material 20 introducing higher lignin concentrations into the aquatic system and resulting in a stronger color of DOM than in the High Arctic. There is a strong relationship between dissolved organic carbon (DOC) concentration and absorption characteristics (cDOM) for surface waters at both sites similar to the one for the great Arctic rivers. We used the optical characteristics of DOM such as cDOM absorption, Specific UltraViolet Absorbance SUVA, UltraViolet UV Slope, Slope Ratio for assessing quality changes downstream, at baseflow and stormflow conditions and in relation to permafrost disturbance. DOM in streams 25 at both sites demonstrated optical signatures indicative of photodegradation downstream processes, even over short distances of 2000 m. It was determined that flow pathways and the connected hydrological residence time control DOM quality. Deeper flow pathways allow the export of permafrost-derived DOM, whereas shallow pathways with shorter residence times lead to the export of fresh near-surface derived DOM. Compared to the large Arctic rivers, DOM quality exported from the small catchments studied here is much fresher and therefore prone to degradation. This work shows that optical properties of DOM 30 will be a useful tool for understanding DOM sources and quality at a pan-Arctic scale.Biogeosciences Discuss., https://doi.for their help in the instrumentation set up, data collection in the field and laboratory analyses. We acknowledge Saskia Foerster and Sabine Chabrillat (GFZ Potsdam) for providing access to the laboratory spectrometer. A special thanks to for their support and helpful insights in the field. Many thanks also to the CBAWO 2017 field team. 15

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

Cited by 63 publications

References 85 publications

Thermokarst Effects on Carbon Dioxide and Methane Fluxes in Streams on the Peel Plateau (NWT, Canada)

Thermokarst Effects on Carbon Dioxide and Methane Fluxes in Streams on the Peel Plateau (NWT, Canada)

Sub-seasonal thaw slump mass wasting is not consistently energy limited at the landscape scale

Characterizing organic matter composition in small Low and High Arctic catchments using terrestrial colored dissolved organic matter (cDOM)

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