Methane and carbon dioxide emissions from 40 lakes along a north–south latitudinal transect in Alaska

Sepulveda‐Jauregui, Armando; Anthony, K. M. Walter; Martinez‐Cruz, Karla; Greene, Samuel M.; Thalasso, F.

doi:10.5194/bg-12-3197-2015

Cited by 160 publications

(147 citation statements)

References 83 publications

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“…Indeed, Cornwell and Kipphut (25) found very low organic matter sedimentation rates and low dissolved oxygen consumption rates within Toolik Lake sediments, suggesting that the methane in Toolik Lake may be from a different origin. Similar spatial distribution patterns of methane, showing highest concentrations close to the lakeshore, have been seen in other Arctic lakes (9,26,27). While other explanations for this spatial distribution are possible (e.g., active slumping of organic-rich soil along the shoreline or wave-induced methane release), this is also consistent with the allochthonous input from the active layer as we propose here, which may contribute to the total lake methane inventory.…”

Section: Resultssupporting

confidence: 88%

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: Resultssupporting

confidence: 88%

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 (CH 4 ) emissions from freshwater environments are expected to increase with warming climates (Juutinen et al, 2009;Yvon-Durocher et al, 2011Tan and Zhuang 2015a, b) but quantitative modeled projections of emissions are poorly constrained (Bastviken et al, 2011;Rasilo et al, 2015;Sepulveda-Jauregui et al, 2015;Tan et al, 2015). Observations of seasonal and annual lake CH 4 dynamics in the Arctic are necessary to define source estimates in models and understand the impact warming may have on greenhouse gas emissions.…”

Section: Introductionmentioning

confidence: 99%

“…During thermal stratification, a lack of mixing between the epilimnion and anoxic hypolimnion suppresses gas transfer between these layers, allowing CH 4 to accumulate below the oxycline (hereafter referred to as storage; Fig. 1; Bastviken et al, 2004;Sepulveda-Jauregui et al, 2015). During mixing from fall turnover, all CH 4 previously stored in the hypolimnion is susceptible to MOx and/or diffusion (Encinas Fernandez et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

“…Under ice cover, CH 4 can accumulate and is either stored under ice or within the ice ( Fig. 1; Walter et al, 2006;Walter Anthony et al, 2012;Sepulveda-Jauregui et al, 2015). In spring, the break-up of the ice and mixing allows stored CH 4 to be oxidized or emitted from the system through diffusion or ebullition (Juutinen et al, 2009;López Bellido et al, 2009;Karlsson et al, 2013;Greene et al, 2014;Jammet et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

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Exceptional summer warming leads to contrasting outcomes for methane cycling in small Arctic lakes of Greenland

2017

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Abstract. In thermally stratified lakes, the greatest annual methane emissions typically occur during thermal overturn events. In July of 2012, Greenland experienced significant warming that resulted in substantial melting of the Greenland Ice Sheet and enhanced runoff events. This unusual climate phenomenon provided an opportunity to examine the effects of short-term natural heating on lake thermal structure and methane dynamics and compare these observations with those from the following year, when temperatures were normal. Here, we focus on methane concentrations within the water column of five adjacent small lakes on the icefree margin of southwestern Greenland under open-water and ice-covered conditions from 2012-2014. Enhanced warming of the epilimnion in the lakes under open-water conditions in 2012 led to strong thermal stability and the development of anoxic hypolimnia in each of the lakes. As a result, during open-water conditions, mean dissolved methane concentrations in the water column were significantly (p < 0.0001) greater in 2012 than in 2013. In all of the lakes, mean methane concentrations under ice-covered conditions were significantly (p < 0.0001) greater than under open-water conditions, suggesting spring overturn is currently the largest annual methane flux to the atmosphere. As the climate continues to warm, shorter ice cover durations are expected, which may reduce the winter inventory of methane and lead to a decrease in total methane flux during ice melt. Under openwater conditions, greater heat income and warming of lake surface waters will lead to increased thermal stratification and hypolimnetic anoxia, which will consequently result in increased water column inventories of methane. This stored methane will be susceptible to emissions during fall overturn, which may result in a shift in greatest annual efflux of methane from spring melt to fall overturn. The results of this study suggest that interannual variation in ground-level air temperatures may be the primary driver of changes in methane dynamics because it controls both the duration of ice cover and the strength of thermal stratification.

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“…Chanton et al (1989) and Walter et al (2008) used the CH 4 /N 2 ratio to document spatial and temporal changes in ebullition rate. Ebullition usually intensifies during summer (Makhov and Bazin 1999;Liikanen et al 2003;Sapulveda-Jauregui et al 2015). However, in the seven coastal lakes studied, the CH 4 /N 2 displayed irregular temporal changes.…”

Section: Discussionmentioning

confidence: 98%

Processes affecting molecular and stable isotope compositions of sediment gas in estuarine waters along the southern Baltic coast (Poland)

et al. 2016

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This paper investigates the molecular and stable isotope compositions of sediment gases from seven coastal lakes along the southern Baltic coast in Poland. The aim is to extend the knowledge of the genesis and distribution of microbial gases in the zone of mixing of fresh and salt waters with special attention to the effect of salinity, climate-related seasonality, and vertical sediment mixing. We found differences in the compositions of gas between the studied lakes and within each lake. These differences are mainly controlled by lake water depth and the presence of macrophytes. Due to the dissolution of rising bubbles in highly oxygenated water, the concentrations of CH 4 and CO 2 show up to 67% decline along the water column in favor of N 2 and O 2 . On the other hand, in vegetated parts of the lakes, the CH 4 is depleted in favor of CO 2 , and the residual CH 4 and CO 2 are enriched in 13 C. Despite the fact that the coastal lakes display highly oxidizing conditions in the water column and that the bottom sediments are mixed by wind waves the CH 4 reveals rather low oxidation. On the basis of the CH 4 /N 2 ratio we established that there are differences in the intensity of ebullition throughout the lakes. Higher intensities of ebullition were found in shallower parts of the lakes. Salinity has no effect on the stable C and H isotope composition of sediment gas. It seems, however, that salinity affects the molecular composition of hydrocarbons via preferential oxidation of CH 4 under higher salinity conditions.

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Methane and carbon dioxide emissions from 40 lakes along a north–south latitudinal transect in Alaska

Cited by 160 publications

References 83 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

Exceptional summer warming leads to contrasting outcomes for methane cycling in small Arctic lakes of Greenland

Processes affecting molecular and stable isotope compositions of sediment gas in estuarine waters along the southern Baltic coast (Poland)

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