Spatial Variability of Dissolved Organic Carbon, Solutes, and Suspended Sediment in Disturbed Low Arctic Coastal Watersheds

Coch, Caroline; Ramage, Justine; Lamoureux, Scott A.; Meyer, Hanno; Knoblauch, Christian; Lantuit, Hugues

doi:10.1029/2019jg005505

Cited by 16 publications

(19 citation statements)

References 57 publications

(87 reference statements)

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“…We measured discharge using a cutthroat flume equipped with a U20 Onset Hobo level logger in Ice Creek West. Discharge data at 30 min intervals are available from 15 May 2016 and at 5 min intervals after 22 July 2016 (Coch et al, 2018(Coch et al, , 2020. In Ice Creek East, discharge was deter-4538 C. Coch et al: Comparing low and high Arctic DOM characteristics Table 1.…”

Section: Field Methods and Hydrochemistrymentioning

confidence: 99%

“…The island is situated in the zone of continuous permafrost with ground ice content between 30 % and 60 % for the entire island. Physical permafrost degradation typically occurs in the form of retrogressive thaw slumps (Lantuit and Pollard, 2008) and active layer detachments (Coch et al, 2020). Ramage et al (2019) reported mean active layer depths of 52.2 ± 20.2 cm.…”

Section: Study Areamentioning

confidence: 99%

“…1b, Table 1). Both sampled ponds in Ice Creek West are < 1 ha, and there are degrading ice-wedge polygons present in the headwaters of Ice Creek West (Coch et al, 2020).…”

Section: Study Areamentioning

confidence: 99%

“…The locations at 2000 and 1300 m from the outflow show distinct high values of DOC and a cDOM 350 compared to the other locations downstream of them. These high concentrations are a result of degrading ice-wedge polygons, which heavily influence DOM in the headwaters of the stream (Coch et al, 2020). The location at 1300 m marks the inflow of another headwater tributary impacted by degrading icewedge polygons.…”

Section: Downstream Patterns Of Dom and Impact Of Permafrost Disturbancementioning

confidence: 99%

“…The following event of 12.7 mm led to a decrease in DOC concentration and S275-295 and an increase in SUVA, indicating an increase in aromaticity and a higher molecular weight -suggesting fresher and lignin-rich plant-derived DOM. A change in water sources for these two rainfall events was examined by Coch et al (2020). Whereas runoff during the 9.3 mm rainfall event showed the signature of supra-permafrost water, which was forced out during that rainfall event, runoff during the subsequent 12.7 mm rainfall event reflected the isotopic signature of rain (Coch et al, 2020).…”

Section: Rainfall Event Impacts On Dommentioning

confidence: 99%

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Comparisons of dissolved organic matter and its optical characteristics in small low and high Arctic catchments

Coch

Juhls²,

Lamoureux

et al. 2019

Biogeosciences

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Abstract. Climate change is affecting the rate of carbon cycling, particularly in the Arctic. Permafrost degradation through deeper thaw and physical disturbances results in the release of carbon dioxide and methane to the atmosphere and to an increase in lateral dissolved organic matter (DOM) fluxes. Whereas riverine DOM fluxes of the large Arctic rivers are well assessed, knowledge 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 (SOCC). The low Arctic site has higher SOCC and greater abundance of plant material resulting in higher chromophoric dissolved organic matter (cDOM) and dissolved organic carbon (DOC) than in the high Arctic. DOC concentration and cDOM in surface waters at both sites show strong linear relationships 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) spectral slopes (S275–295), and slope ratio (SR) for assessing quality changes downstream, at base flow and storm flow conditions, and in relation to permafrost disturbance. DOM in streams at both sites demonstrated optical signatures indicative of photodegradation downstream processes, even over short distances of 2000 m. Flow pathways and the connected hydrological residence time control DOM quality. Deeper flow pathways allow the export of permafrost-derived DOM (i.e. from deeper in the active layer), whereas shallow pathways with shorter residence times lead to the export of fresh surface- and 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. Assessing optical properties of DOM and linking them to catchment properties will be a useful tool for understanding changing DOM fluxes and quality at a pan-Arctic scale.

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Section: Field Methods and Hydrochemistrymentioning

confidence: 99%

Section: Study Areamentioning

confidence: 99%

“…1b, Table 1). Both sampled ponds in Ice Creek West are < 1 ha, and there are degrading ice-wedge polygons present in the headwaters of Ice Creek West (Coch et al, 2020).…”

Section: Study Areamentioning

confidence: 99%

Section: Downstream Patterns Of Dom and Impact Of Permafrost Disturbancementioning

confidence: 99%

Section: Rainfall Event Impacts On Dommentioning

confidence: 99%

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Comparisons of dissolved organic matter and its optical characteristics in small low and high Arctic catchments

Coch

Juhls²,

Lamoureux

et al. 2019

Biogeosciences

Self Cite

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Advances in retrogressive thaw slump research in permafrost regions

Li,

Liu,

Chen

et al. 2024

Permafrost & Periglacial

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A retrogressive thaw slump (RTS) is a slope failure formed by slope thaw settlement and retrogressive slump following the thawing of ice‐rich permafrost or the melting of massive ice. Here, we review recent literature on RTSs, one of the main geomorphological landscapes developed in the process of permafrost degradation. The main topics are as follows: development and temporal evolution, mechanisms and processes, influencing factors, evaluation susceptibility and calculation, and assessment of engineering and environmental impacts. There has been a rapid increase in the number and distribution area of RTSs over permafrost in recent years. Climate warming events, extreme rainfall, forest fires, bank and coast erosion, and anthropogenic activity are the primary factors leading to RTSs in permafrost regions, disrupting the initial hydrothermal equilibrium of permafrost slopes. This causes a rise in ground temperature and the thaw of ice‐rich permafrost. Meltwater seeps down and collects on the ice surface, weakening freeze–thaw interface shear resistance and resulting in soil collapse. The development of RTSs may last several decades or longer. RTSs destabilize infrastructure, destroy vegetation, boost soil erosion and land desertification, alter the environment of nearby waters, and increase emissions of some major greenhouse gases. Numerous methods have been developed and adopted to explore RTSs, including geographic information systems (GIS) and equilibrium, numerical, and reliability analysis methods. However, research on formation mechanisms and processes, quantitative prediction, engineering and environmental influences, and mitigative measures of RTSs under a warming climate are still inadequate. Existing research methods, such as numerical simulations, remote sensing, airborne ground‐based geophysical surveys, investigations and mapping, and hydrothermal and deformation field monitoring, should be systematically integrated. Additionally, equipment for laboratory testing and numerical models for simulating RTSs may need to be timely introduced and better developed.

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