Using radon to quantify groundwater discharge and methane fluxes to a shallow, tundra lake on the Yukon-Kuskokwim Delta, Alaska

Dabrowski, Jessica S.; Charette, Matthew A.; Mann, P.; Ludwig, S.; Natali, Susan M.; Holmes, Robert M.; Schade, J. D.; Powell, M.; Henderson, Paul B.

doi:10.1007/s10533-020-00647-w

Cited by 41 publications

(35 citation statements)

References 64 publications

(115 reference statements)

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“…GW often contains high concentration of CH 4 compared to lake water due to anoxic conditions prevailing in soils (Bugna et al, 1996). Moreover, GW can also be a significant source of CH 4 to some lakes (Einarsdottir et al, 2017;Lecher et al, 2017;Dabrowski et al, 2020). A previous study indicates that large amounts of CH 4 might be transported to STJ via GW inputs (Denfeld et al, 2020).…”

Section: Groundwater Influence On Ch 4 In Lake Stortjärnmentioning

confidence: 99%

Methane in Lakes: Variability in Stable Carbon Isotopic Composition and the Potential Importance of Groundwater Input

et al. 2021

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Methane (CH4) is an important component of the carbon (C) cycling in lakes. CH4 production enables carbon in sediments to be either reintroduced to the food web via CH4 oxidation or emitted as a greenhouse gas making lakes one of the largest natural sources of atmospheric CH4. Large stable carbon isotopic fractionation during CH4 oxidation makes changes in 13C:12C ratio (δ13C) a powerful and widely used tool to determine the extent to which lake CH4 is oxidized, rather than emitted. This relies on correct δ13C values of original CH4 sources, the variability of which has rarely been investigated systematically in lakes. In this study, we measured δ13C in CH4 bubbles in littoral sediments and in CH4 dissolved in the anoxic hypolimnion of six boreal lakes with different characteristics. The results indicate that δ13C of CH4 sources is consistently higher (less 13C depletion) in littoral sediments than in deep waters across boreal and subarctic lakes. Variability in organic matter substrates across depths is a potential explanation. In one of the studied lakes available data from nearby soils showed correspondence between δ13C-CH4 in groundwater and deep lake water, and input from the catchment of CH4via groundwater exceeded atmospheric CH4 emissions tenfold over a period of 1 month. It indicates that lateral hydrological transport of CH4 can explain the observed δ13C-CH4 patterns and be important for lake CH4 cycling. Our results have important consequences for modelling and process assessments relative to lake CH4 using δ13C, including for CH4 oxidation, which is a key regulator of lake CH4 emissions.

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Section: Groundwater Influence On Ch 4 In Lake Stortjärnmentioning

confidence: 99%

Methane in Lakes: Variability in Stable Carbon Isotopic Composition and the Potential Importance of Groundwater Input

et al. 2021

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“…In Chapter 2, I applied 222 Rn as a tracer of groundwater discharge and methane sources in a shallow, tundra lake in the in subarctic Alaska (Dabrowski et al, 2019); although 222 Rn was used once before to quantify groundwater discharge into an Arctic lake , the type of lake in this study is much more common across the Arctic, and therefore has greater implications for groundwater sources and carbon budgets in the Arctic freshwater system. First, I used a mass balance approach to quantify all sources and sinks of 222 Rn into the lake other than groundwater, and then solved for the groundwater discharge flux by difference.…”

Section: Resultsmentioning

confidence: 99%

Radium isotopes and radon-222 as tracers of sediment-water interaction in Arctic coastal and lacustrine environments

Dabrowski¹

2020

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Arctic marine and lacustrine systems are experiencing rapid warming due to climate change. These changes are especially important at the interface between sediments and surface waters because they are hotspots for biogeochemical transformations such as redox reactions, nutrient consumption and regeneration, organic matter leaching and degradation, and mineral weathering. Radium isotopes (223 Ra, 224 Ra, 226 Ra, 228 Ra) and radon-222, naturally occurring radioactive isotopes produced in sediments, are well-suited as tracers of nutrients, trace metals, and organic matter cycling processes at the sediment-water interface. In this thesis, I have applied radon-222 and the quartet of radium isotopes to study fundamental processes in subarctic lakes and on the Arctic continental shelf.

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“…Active layer groundwater flow discharging into the ponds was estimated using a radon ( 222 Rn) mass balance approach (Dabrowski et al, 2020;Dimova et al, 2013). Radon (Rn, hereafter) is a radioactive (half-life of 3.8 days) noble gas that is produced from the radioactive decay of 226 Ra (Ra, hereafter), which occurs ubiquitously in rocks, soils, and sediments and, to a lesser extent, by decay of dissolved Ra.…”

Section: Conceptual Model For Estimating Active Layer Groundwater Discharge Using Radon ( 222 Rn)mentioning

confidence: 99%

“…High CH 4 concentrations in freshwaters are usually ascribed to high CH 4 production rates in anoxic sediments (Bastviken et al, 2004) or in the oxic water column (DelSontro et al, 2018). However, high CH 4 concentrations in freshwaters in permafrost regions can also result from the large supply of externally produced CH 4 through active layer groundwater discharge (Connolly et al, 2020;Dabrowski et al, 2020;Paytan et al, 2015). Here, active layer groundwater discharge flow is defined as the supra-permafrost groundwater flow that circulates through the unfrozen zone of the active layer due to the hydraulic gradient and discharges into surface waters.…”

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confidence: 99%

“…Here, active layer groundwater discharge flow is defined as the supra-permafrost groundwater flow that circulates through the unfrozen zone of the active layer due to the hydraulic gradient and discharges into surface waters. The active layer groundwater flow is CH 4 -rich and accounts for a large fraction of CH 4 emissions from lakes and streams in permafrost regions (Dabrowski et al, 2020;Kling et al, 1992;Lecher et al, 2017;Paytan et al, 2015). While climate change is expected to have profound influences on the hydrology of the Arctic by reducing the permafrost extent and increasing the thickness of the active layer (Vihma et al, 2016;Woo et al, 2008), little information is available on the overall transport of CH 4 from the active layer into thaw ponds.…”

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confidence: 99%

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The role of methane transport from the active layer in sustaining methane emissions and food chains in subarctic ponds

Olid

Zannella

Lau

2021

Preprint

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Shallow groundwater flow from the seasonally thawed active layer is increasingly recognized as an important pathway for delivering methane (CH4) into Arctic lakes and streams, but its contribution to CH4 emissions from thaw ponds has not been evaluated. Furthermore, the potential influence of the shallow groundwater-derived CH4 on the trophic support and nutritional quality of thaw pond food chains remains unexplored. In this study, we used a radon-mass balance approach to quantify the CH4 transport from the active layer into thaw ponds in a sub-Arctic catchment. We analysed stable isotopes and fatty acids of pond macroinvertebrates to evaluate the potential effects of CH4 inputs through active layer groundwater flows on the aquatic food chains. Our results indicate that CH4 fluxes from the active layer can sustain CH4 emissions from the ponds. Consumers in ponds receiving greater CH4 inputs from the active layer had lower stable carbon isotope signatures that indicates a greater trophic reliance on methane oxidizing bacteria (MOB), and they had lower nutritional quality as indicated by their lower tissue concentrations of polyunsaturated fatty acids. Accurate predictions of CH4 release from small thaw ponds will thus require improved knowledge of the contributions from various processes including internal production, flow paths of active layer groundwater, and MOB-consumer interactions.

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Using radon to quantify groundwater discharge and methane fluxes to a shallow, tundra lake on the Yukon-Kuskokwim Delta, Alaska

Abstract: Using radon to quantify groundwater discharge and methane fluxes to a shallow, tundra lake on the Yukon-Kuskokwim Delta, Alaska. Biogeochemistry, 148 (1). pp. 69-89.

Cited by 41 publications

References 64 publications

Methane in Lakes: Variability in Stable Carbon Isotopic Composition and the Potential Importance of Groundwater Input

Methane in Lakes: Variability in Stable Carbon Isotopic Composition and the Potential Importance of Groundwater Input

Radium isotopes and radon-222 as tracers of sediment-water interaction in Arctic coastal and lacustrine environments

The role of methane transport from the active layer in sustaining methane emissions and food chains in subarctic ponds

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