Methane emissions from oceans, coasts, and freshwater habitats: New perspectives and feedbacks on climate

Hamdan, Leila J.; Wickland, Kimberly P.

doi:10.1002/lno.10449

Cited by 52 publications

(27 citation statements)

References 81 publications

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“…Natural sources, including freshwaters, account for about 35–50% of the global CH 4 emissions (Ciais et al, ). Freshwater CH 4 emissions are sensitive to climate change and expected to increase in the future (Campeau & Del Giorgio, ; Hamdan & Wickland, ). Moreover, estimates of freshwater CH 4 emissions from lentic and lotic systems represent an important source of uncertainty in the global CH 4 budget due to high spatial and temporal variability of fluxes and very uncertain surface areas (Saunois et al, ).…”

Section: Introductionmentioning

confidence: 99%

Sediment Properties Drive Spatial Variability of Potential Methane Production and Oxidation in Small Streams

2020

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Emissions of the potent greenhouse gas methane (CH 4 ) from streams and rivers are a significant component of global freshwater methane emissions. The distribution of CH 4 production and oxidation within stream sections and in vertical sediment profiles is not well understood, and the environmental controls on CH 4 production and emission in such systems create a significant challenge for assessing larger-scale dynamics. Here we investigate factors driving the spatial variability of sediment potential methane production (PMP) and potential methane oxidation (PMO) in a temperate stream network in Germany. PMP was highly variable, ranging from 5 × 10 −4 to 28.58 μg CH 4 gDW −1 d −1 and PMO ranged from 0.43 μg CH 4 gDW −1 d −1 to 14.41 μg CH 4 gDW −1 d −1 . Important drivers of spatial variability of PMP and PMO in the sediments of the stream main-stem were related to fine sediment fraction and organic carbon content. At smaller spatial scale, that is, in a sub-catchment stream section, the drivers were more complex and included sediment nitrogen and organic carbon content, as well as porewater dissolved organic carbon, dissolved organic matter quality, and metal concentrations. As with reservoirs and impounded rivers, fine sediment deposition and organic carbon content were found to be key controls on the spatial variability of CH 4 production and oxidation. These findings enhance our understanding of CH 4 dynamics, improve the potential for identifying CH 4 production hotspots in small streams, and provide a potential means for upscaling emission rates in larger-scale assessments.Plain Language Summary Globally, streams and rivers emit a significant amount of the highly potent greenhouse gas methane. The methane emitted from streams is mainly produced in sediments. The distribution of production and consumption in stream sections and sediment profiles is not well understood, which creates a significant challenge for estimating, for example, regional methane emissions from streams and rivers. We investigated possible factors controlling the variability from site to site and different depths of methane production and consumption in sediments of a stream network in south-west Germany. Sediment properties, the amount of fine sediment and organic carbon content, were key drivers of this variability in the main stream. In a smaller side arm of the main stream, the drivers were more complex, including nitrogen and organic carbon content of the sediment, but also porewater dissolved organic carbon, dissolved organic matter quality, and metals. As for reservoirs and dammed rivers, the accumulation of fine sediments and organic carbon content was found to be key controls of sediment methane production and consumption. These findings enhance our understanding of methane dynamics, improve the potential for identifying methane production hotspots in small streams, and provide a potential means for upscaling emission rates in larger-scale assessments.

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Section: Introductionmentioning

confidence: 99%

Sediment Properties Drive Spatial Variability of Potential Methane Production and Oxidation in Small Streams

2020

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“…Sources of methane emission into the atmosphere can be di vided into 2 categories: anthropogenic (~60%) and natural (~40%) (Kirschke et al 2013). Freshwater environments, such as lakes and rivers, and near-shore marine environments, such as shelf areas and estuaries, are important natural methane sources (Bast viken et al 2011, Kirschke et al 2013, Hamdan & Wickland 2016). According to Kirschke et al (2013), freshwater and geological sources including oceans contribute up to 27% of methane emissions from natural sources.…”

Section: Introductionmentioning

confidence: 99%

“…According to Kirschke et al (2013), freshwater and geological sources including oceans contribute up to 27% of methane emissions from natural sources. Coastal and estuarine environments, in turn, may contribute up to 75% of global methane emission from brackish and marine environments combined (Hamdan & Wickland 2016).…”

Section: Introductionmentioning

confidence: 99%

Effect of salinity on microbial methane oxidation in freshwater and marine environments

Osudar¹,

Klings²,

Wagner³

et al. 2017

Aquat. Microb. Ecol.

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Salinity is an important environmental control of aerobic methane oxidation, which reduces the emission of the potent greenhouse gas methane into the atmosphere. The effect of salinity on methane oxidation is especially severe in river estuaries and adjacent coastal waters, which are important sources of methane emission and, at the same time, are usually characterized by pronounced salinity gradients. Using methane oxidation rates determined by a radiotracer technique as a measure of methanotrophic activity, we tested the effect of immediate and gradual salinity changes on pure cultures of methanotrophic bacteria, and natural freshwater (Elbe River) and natural marine (North Sea) methanotrophic populations. According to our results, Methylomonas sp. and Methylosinus trichosporium are resistant to an increase in salinity, whereas Methylovulum sp. and Methylobacter luteus are sensitive to such an increase. Natural methanotrophic populations from freshwater are more resistant to an increase in salinity than those from marine water are to a decrease in salinity. In contrast to an immediate change of salinity, gradual change (1.25 PSU d −1) can attenuate salinity stress. Experiments with the natural populations revealed different reactions to changes in salinity; thus, we assume that the initial composition of the methanotrophic population, i.e. the ratio of sensitive versus resistant strains, also governs the community response to salinity stress.

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“…Growing evidence indicates that the global methane budget may be influenced by methane release from freshwater systems (e.g., Bastviken et al 2004;Ciais et al 2013;Hamdan and Wickland 2016) and shallow coastal areas in marine systems (Borges et al 2016, whereas the open ocean (excluding areas with hydrates, especially in the arctic) is a minor contributor (Bates et al 1996;Rhee et al 2009). Freshwater studies encompassing arctic (Kling et al 1992;Laurion et al 2010), boreal (Bastviken et al 2004;Huttunen et al 2003), and temperate (e.g., Michmerhuizen et al 1996) systems, have led to an estimated emission of 103 Tg methane year À1 from lakes, reservoirs, and rivers (Bastviken et al 2011).…”

Section: Introductionmentioning

confidence: 99%

Integrating isotopic, microbial, and modeling approaches to understand methane dynamics in a frequently disturbed deep reservoir in Taiwan

Itoh

Kojima

et al. 2017

Ecological Research

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It has been estimated that more than 48% of global methane emissions from lakes and reservoirs occur at low latitudes (<24°). To improve this estimate, knowledge regarding underexplored ecosystems, particularly deep lakes and reservoirs in Asian monsoon regions, is needed because the magnitude of methane emissions is influenced by lake bathymetry and climatic conditions. We conducted long‐term studies beginning in 2004 at Feitsui Reservoir (FTR) in Taiwan, a subtropical monomictic system with a maximum depth of 120 m to monitor seasonal and interannual variations of three key characteristics and to understand the mechanisms underlying these variations. Key characteristics investigated were as follows: (1) the balance of primary production and heterotrophic respiration as a determinant of vertical oxygen distribution, (2) methane production at the bottom of the reservoir, oxidation in the water column, and emissions from the lake surface, and (3) the contribution of methane‐originated carbon to the pelagic food web through methane‐oxidizing bacteria (MOB). This review highlights major achievements from FTR studies integrating isotopic, microbial, and modeling approaches. Based on our findings, we proposed two conceptual models: (1) a model of methane dynamics, which addresses the differences in methane emission mechanisms between deep and shallow lakes, and (2) a spatially explicit model linking benthic methane production to the pelagic food web, which addresses the diversity of MOB metabolisms and their dependence on oxygen availability. Finally, we address why long‐term studies of subtropical lakes and reservoirs are important for better understanding the effects of climate on low‐ to mid‐latitude ecosystems.

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Methane emissions from oceans, coasts, and freshwater habitats: New perspectives and feedbacks on climate

Cited by 52 publications

References 81 publications

Sediment Properties Drive Spatial Variability of Potential Methane Production and Oxidation in Small Streams

Sediment Properties Drive Spatial Variability of Potential Methane Production and Oxidation in Small Streams

Effect of salinity on microbial methane oxidation in freshwater and marine environments

Integrating isotopic, microbial, and modeling approaches to understand methane dynamics in a frequently disturbed deep reservoir in Taiwan

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