Ephemerality of discrete methane vents in lake sediments

Scandella, Benjamin P.; Pillsbury, Liam; Weber, Thomas C.; Ruppel, Carolyn D.; Hemond, Harold F.; Juanes, Rubén

doi:10.1002/2016gl068668

Cited by 37 publications

(50 citation statements)

References 37 publications

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“…In all these environments, especially shallow waters, the total gas pressure can exceed the ambient hydrostatic pressure, resulting in the formation of CH 4 bubbles in the sediment (Maeck et al, ). Transport through ebullition is faster than through diffusion, although ebullition can also be highly episodic (Scandella et al, ), allowing CH 4 to bypass the geochemical barrier of oxygen and SO 4 2− (Figure ) (DelSontro et al, ). In the intertidal zone in estuaries and in mangroves, CH 4 may also be transferred directly from sediments to the atmosphere (Borges & Abril, ).…”

Section: Marine and Freshwater Systemsmentioning

confidence: 99%

Methane Feedbacks to the Global Climate System in a Warmer World

Dean

Middelburg

Röckmann

et al. 2018

Reviews of Geophysics

450

341

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Methane (CH4) is produced in many natural systems that are vulnerable to change under a warming climate, yet current CH4 budgets, as well as future shifts in CH4 emissions, have high uncertainties. Climate change has the potential to increase CH4 emissions from critical systems such as wetlands, marine and freshwater systems, permafrost, and methane hydrates, through shifts in temperature, hydrology, vegetation, landscape disturbance, and sea level rise. Increased CH4 emissions from these systems would in turn induce further climate change, resulting in a positive climate feedback. Here we synthesize biological, geochemical, and physically focused CH4 climate feedback literature, bringing together the key findings of these disciplines. We discuss environment‐specific feedback processes, including the microbial, physical, and geochemical interlinkages and the timescales on which they operate, and present the current state of knowledge of CH4 climate feedbacks in the immediate and distant future. The important linkages between microbial activity and climate warming are discussed with the aim to better constrain the sensitivity of the CH4 cycle to future climate predictions. We determine that wetlands will form the majority of the CH4 climate feedback up to 2100. Beyond this timescale, CH4 emissions from marine and freshwater systems and permafrost environments could become more important. Significant CH4 emissions to the atmosphere from the dissociation of methane hydrates are not expected in the near future. Our key findings highlight the importance of quantifying whether CH4 consumption can counterbalance CH4 production under future climate scenarios.

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Section: Marine and Freshwater Systemsmentioning

confidence: 99%

Methane Feedbacks to the Global Climate System in a Warmer World

Dean

Middelburg

Röckmann

et al. 2018

Reviews of Geophysics

450

341

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“…Comas and Wright [] observed bubbles released from methane‐generating peat with a downward looking camera both in situ and in a laboratory sample, but their focus was on quantifying the temporal variability in ebullition, rather than understanding the spatial component of interest here. Interestingly, that study found a positive correlation between atmospheric pressure and the ebullitive flux, compared with the majority of studies, which find that ebullition is triggered by falling atmospheric pressure [ Mattson and Likens , ; Fechner‐Levy and Hemond , ; Tokida et al , ; Scandella et al , ; Varadharajan and Hemond , ; Yvon‐Durocher et al , ; Scandella et al , ], among other factors. Further experiments on wetland sediments have demonstrated triggering of ebullition with ebbing and flowing tides but did not detect the release of individual bubbles or quantify the spatial variability in ebullition [ Chen and Slater , ].…”

Section: Introductionmentioning

confidence: 71%

“…However, at least in some settings, the spatial structure of distant methane vents is ephemeral. In a record of sonar‐detected ebullition in Upper Mystic Lake (UML), MA, a characteristic spatial structure of apparently discrete seeps was observed over periods up to 1 day in duration, but over longer periods the occurrence of spatially independent venting made the pattern indistinguishable from a completely spatially random process [ Scandella et al , ]. Other studies on the UML, a dimictic, eutrophic kettle lake north of Boston, MA, include a 4 month record of ebullition from five surface‐moored bubble traps that showed surprising synchronicity in hydrostatically triggered ebullition episodes, despite the sensors' being located over water depths ranging from 9 to 25 m [ Scandella et al , ; Varadharajan and Hemond , ; Delwiche et al , ].…”

Section: Introductionmentioning

confidence: 99%

Persistence of bubble outlets in soft, methane‐generating sediments

et al. 2017

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Sediments submerged beneath many inland waterways and shallow oceans emit methane, a potent greenhouse gas, but the magnitude of the methane flux to the atmosphere remains poorly constrained. In many settings, the majority of methane is released through bubbling, and the spatiotemporal heterogeneity of this ebullition both presents challenges for measurement and impacts bubble dissolution and atmospheric emissions. Here we present laboratory‐scale experiments of methane ebullition in a controlled incubation of reconstituted sediments from a eutrophic lake. Image analysis of a 0.14 m2 sediment surface area allowed identification of individual bubble outlets and resolved their location to ∼1 cm. While ebullition events were typically concentrated in bursts lasting ∼2 min, some major outlets showed persistent activity over the scale of days and even months. This persistence was surprising given the previously observed ephemerality of spatial structure at the field scale. This persistence suggests that, at the centimeter scale, conduits are reopened as a result of a drop in tensile strength due to deformation of sediments by the rising bubbles. The mechanistic insight from this work sheds light on the spatiotemporal distribution of methane venting from organic‐rich sediments and has important implications for bubble survival in the water column and associated biogeochemical pathways of methane.

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“…Thus, despite the bubble-sediment material system existing in an apparently stable, time-independent state, the system is not actually in its lowest energy state. A small increase in applied force can lead to a number of different responses from no motion of the bubble to a large jump and removal of the bubble from the sediment matrix (Scandella et al, 2011(Scandella et al, , 2016.…”

Section: Emission Uncertainty and Self-organized Criticalitymentioning

confidence: 99%

Variability in methane emissions from West Siberia's shallow boreal lakes on a regional scale and its environmental controls

et al. 2017

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Abstract. Small lakes represent an important source of atmospheric CH 4 from northern wetlands. However, spatiotemporal variations in flux magnitudes and the lack of knowledge about their main environmental controls contribute large uncertainty into the global CH 4 budget. In this study, we measured methane fluxes from small lakes using chambers and bubble traps. Field investigations were carried out in JulyAugust 2014 within the West Siberian middle and southern taiga zones. The average and median of measured methane chamber fluxes were 0.32 and 0.30 mgCH 4 m −2 h −1 for middle taiga lakes and 8.6 and 4.1 mgCH 4 m −2 h −1 for southern taiga lakes, respectively. Pronounced flux variability was found during measurements on individual lakes, between individual lakes and between zones. To analyze these differences and the influences of environmental controls, we developed a new dynamic process-based model. It shows good performance with emission rates from the southern taiga lakes and poor performance for individual lakes in the middle taiga region. The model shows that, in addition to wellknown controls such as temperature, pH and lake depth, there are significant variations in the maximal methane production potential between these climatic zones. In addition, the model shows that variations in gas-filled pore space in lake sediments are capable of controlling the total methane emissions from individual lakes. The CH 4 emissions exhibited distinct zonal differences not only in absolute values but also in their probability density functions: the middle taiga lake fluxes were best described by a lognormal distribution while the southern taiga lakes followed a power-law distribution. The latter suggests applicability of self-organized criticality theory for methane emissions from the southern taiga zone, which could help to explain the strong variability within individual lakes.

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Ephemerality of discrete methane vents in lake sediments

Cited by 37 publications

References 37 publications

Methane Feedbacks to the Global Climate System in a Warmer World

Methane Feedbacks to the Global Climate System in a Warmer World

Persistence of bubble outlets in soft, methane‐generating sediments

Variability in methane emissions from West Siberia's shallow boreal lakes on a regional scale and its environmental controls

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