Interactions between Elevated CO<sub>2</sub>and Warming Could Amplify DOC Exports from Peatland Catchments

Fenner, Nathalie; Freeman, Christopher; Lock, Maurice A.; Harmens, Harry; Reynolds, B.; Sparks, Tim H.

doi:10.1021/es061765v

Cited by 135 publications

(127 citation statements)

References 43 publications

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“…Importantly, the controls on methane input to lakes from the active layer are fundamentally different from those impacting in situ methane production rates within the lakes, and the response of these disparate processes to climate and environmental change is also likely to be distinct (28). Future methane and other carbon emissions from the Arctic, as well as the ecological and economic impacts of these sources and their response to climate change remain topics of great interest (3,(29)(30)(31)(32)(33)(34). The accuracy of atmospheric methane emissions predictions, and ultimately the extent of climate change that can be expected in the Arctic, depends on a holistic understanding of Arctic methane dynamics, including processes within the permafrost active layer.…”

Section: Resultsmentioning

confidence: 99%

Methane transport from the active layer to lakes in the Arctic using Toolik Lake, Alaska, as a case study

Paytan

Lecher

Dimova

et al. 2015

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

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Methane emissions in the Arctic are important, and may be contributing to global warming. While methane emission rates from Arctic lakes are well documented, methods are needed to quantify the relative contribution of active layer groundwater to the overall lake methane budget. Here we report measurements of natural tracers of soil/groundwater, radon, and radium, along with methane concentration in Toolik Lake, Alaska, to evaluate the role active layer water plays as an exogenous source for lake methane. Average concentrations of methane, radium, and radon were all elevated in the active layer compared with lake water (1.6 × 104 nM, 61.6 dpm⋅m−3, and 4.5 × 105 dpm⋅m−3 compared with 1.3 × 102 nM, 5.7 dpm⋅m−3, and 4.4 × 103 dpm⋅m−3, respectively). Methane transport from the active layer to Toolik Lake based on the geochemical tracer radon (up to 2.9 g⋅m−2⋅y−1) can account for a large fraction of methane emissions from this lake. Strong but spatially and temporally variable correlations between radon activity and methane concentrations (r2 > 0.69) in lake water suggest that the parameters that control methane discharge from the active layer also vary. Warming in the Arctic may expand the active layer and increase the discharge, thereby increasing the methane flux to lakes and from lakes to the atmosphere, exacerbating global warming. More work is needed to quantify and elucidate the processes that control methane fluxes from the active layer to predict how this flux might change in the future and to evaluate the regional and global contribution of active layer water associated methane inputs.

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Section: Resultsmentioning

confidence: 99%

Methane transport from the active layer to lakes in the Arctic using Toolik Lake, Alaska, as a case study

Paytan

Lecher

Dimova

et al. 2015

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

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“…1 elevated CO 2 is an increase in labile carbon availability as a consequence of increased plant productivity and biomass (Megonigal et al 1999(Megonigal et al , 2004Vann and Megonigal 2003;Cheng et al 2006). Elevated CO 2 has been shown to increase DOC export from peatland systems (Freeman et al 2004;Fenner et al 2007a) as a result of increased DOC from recent plant productivity (Fenner et al 2007b). In this brackish system, a similar mechanism may explain observed increases in rates of sulfate reduction.…”

Section: Anaerobic Heterotrophic Metabolismmentioning

confidence: 97%

Elevated CO2 affects porewater chemistry in a brackish marsh

et al. 2009

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As atmospheric CO 2 concentrations continue to rise and impact plant communities, concomitant shifts in belowground microbial processes are likely, but poorly understood. We measured monthly porewater concentrations of sulfate, sulfide, methane (CH 4 ), dissolved inorganic carbon and dissolved organic carbon over a 5-year period in a brackish marsh. Samples were collected using porewater wells (i.e., sippers) in a Schoenoplectus americanus-dominated (C 3 sedge) community, a Spartina patensdominated (C 4 grass) community and a mixed (C 3 and C 4 ) community within the marsh. Plant communities were exposed to ambient and elevated (ambient ? 340 ppm) CO 2 levels for 15 years prior to porewater sampling, and the treatments continued over the course of our sampling. Sulfate reduction was stimulated by elevated CO 2 in the C 3 -dominated community, but not in the C 4 -dominated community. Elevated CO 2 also resulted in higher porewater concentrations of CH 4 and dissolved organic carbon in the C 3 -dominated system, though inhibition of CH 4 production by sulfate reduction appears to temper the porewater CH 4 response. These patterns mirror the typical divergent responses of C 3 and C 4 plants to elevated CO 2 seen in this ecosystem. Porewater concentrations of nitrogen (as ammonium) and phosphorus did not decrease despite increased plant biomass in the C 3 -dominated community, suggesting nutrients do not strongly limit the sustained vegetation response to elevated CO 2 . Overall, our data demonstrate that elevated CO 2 drives changes in porewater chemistry and suggest that increased plant productivity likely stimulates microbial decomposition through increases in dissolved organic carbon availability.

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“…Overflow of carbon to secondary structural and defense compounds leads to higher C : nitrogen ratios and reduced bioavailability. Shifts in peatland plant species composition under elevated CO 2 concentrations and air temperatures boost DOC export (Fenner et al 2007). …”

Section: Current Role Of Lakes In the Global C Cyclementioning

confidence: 99%

Lakes and reservoirs as regulators of carbon cycling and climate

Tranvik

Downing

Cotner

et al. 2009

Limnology & Oceanography

2,231

1,756

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We explore the role of lakes in carbon cycling and global climate, examine the mechanisms influencing carbon pools and transformations in lakes, and discuss how the metabolism of carbon in the inland waters is likely to change in response to climate. Furthermore, we project changes as global climate change in the abundance and spatial distribution of lakes in the biosphere, and we revise the estimate for the global extent of carbon transformation in inland waters. This synthesis demonstrates that the global annual emissions of carbon dioxide from inland waters to the atmosphere are similar in magnitude to the carbon dioxide uptake by the oceans and that the global burial of organic carbon in inland water sediments exceeds organic carbon sequestration on the ocean floor. The role of inland waters in global carbon cycling and climate forcing may be changed by human activities, including construction of impoundments, which accumulate large amounts of carbon in sediments and emit large amounts of methane to the atmosphere. Methane emissions are also expected from lakes on melting permafrost. The synthesis presented here indicates that (1) inland waters constitute a significant component of the global carbon cycle, (2) their contribution to this cycle has significantly changed as a result of human activities, and (3) they will continue to change in response to future climate change causing decreased as well as increased abundance of lakes as well as increases in the number of aquatic impoundments.

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Interactions between Elevated CO₂and Warming Could Amplify DOC Exports from Peatland Catchments

Cited by 135 publications

References 43 publications

Methane transport from the active layer to lakes in the Arctic using Toolik Lake, Alaska, as a case study

Methane transport from the active layer to lakes in the Arctic using Toolik Lake, Alaska, as a case study

Elevated CO2 affects porewater chemistry in a brackish marsh

Lakes and reservoirs as regulators of carbon cycling and climate

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Interactions between Elevated CO2and Warming Could Amplify DOC Exports from Peatland Catchments

Cited by 135 publications

References 43 publications

Methane transport from the active layer to lakes in the Arctic using Toolik Lake, Alaska, as a case study

Methane transport from the active layer to lakes in the Arctic using Toolik Lake, Alaska, as a case study

Elevated CO2 affects porewater chemistry in a brackish marsh

Lakes and reservoirs as regulators of carbon cycling and climate

Contact Info

Product

Resources

About

Interactions between Elevated CO₂and Warming Could Amplify DOC Exports from Peatland Catchments