Methane dynamics in the Willamette River, Oregon

Streams and rivers can substantially modify organic carbon (OC) inputs from terrestrial landscapes, and much of this processing is the result of microbial respiration. While carbon dioxide (CO2) is the major end‐product of ecosystem respiration, methane (CH4) is also present in many fluvial environments even though methanogenesis typically requires anoxic conditions that may be scarce in these systems. Given recent recognition of the pervasiveness of this greenhouse gas in streams and rivers, we synthesized existing research and data to identify patterns and drivers of CH4, knowledge gaps, and research opportunities. This included examining the history of lotic CH4 research, creating a database of concentrations and fluxes (MethDB) to generate a global‐scale estimate of fluvial CH4 efflux, and developing a conceptual framework and using this framework to consider how human activities may modify fluvial CH4 dynamics. Current understanding of CH4 in streams and rivers has been strongly influenced by goals of understanding OC processing and quantifying the contribution of CH4 to ecosystem C fluxes. Less effort has been directed towards investigating processes that dictate in situ CH4 production and loss. CH4 makes a meager contribution to watershed or landscape C budgets, but streams and rivers are often significant CH4 sources to the atmosphere across these same spatial extents. Most fluvial systems are supersaturated with CH4 and we estimate an annual global emission of 26.8 Tg CH4, equivalent to ~15‐40% of wetland and lake effluxes, respectively. Less clear is the role of CH4 oxidation, methanogenesis, and total anaerobic respiration to whole ecosystem production and respiration. Controls on CH4 generation and persistence can be viewed in terms of proximate controls that influence methanogenesis (organic matter, temperature, alternative electron acceptors, nutrients) and distal geomorphic and hydrologic drivers. Multiple controls combined with its extreme redox status and low solubility result in high spatial and temporal variance of CH4 in fluvial environments, which presents a substantial challenge for understanding its larger‐scale dynamics. Further understanding of CH4 production and consumption, anaerobic metabolism, and ecosystem energetics in streams and rivers can be achieved through more directed studies and comparison with knowledge from terrestrial, wetland, and aquatic disciplines.

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“…, Schindler and Krabbenhoft , Anthony et al. ), and connection to inundated floodplains (Richey et al. , Pulliam , Teodoru et al.…”

Section: A Framework For Controls On Ch4 In Streams and Riversmentioning

confidence: 99%

The ecology of methane in streams and rivers: patterns, controls, and global significance

Stanley

Casson

Christel

et al. 2016

Ecological Monographs

412

335

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“…But hydrologic linkage to suitable habitats can deliver CH 4 to the channel, and in fact, many studies point to CH 4 production outside the active channel boundaries. Examples of hydrologic linkages that deliver CH 4 include shallow groundwater flows that travel from saturated soils or peat deposits to the channel (Jones and Mulholland 1998a, Hope et al 2001, Crawford et al 2014b, water passing through hyporheic sediments (Baker et al 1994, Schindler and Krabbenhoft 1998, Anthony et al 2012, and connection to inundated floodplains (Richey et al 1988, Pulliam 1993, Teodoru et al 2015 or adjacent wetlands (Crawford et al 2013, Bresney et al 2015. Focused groundwater discharge can create small-scale spatial heterogeneity in CH 4 Mulholland 1998a, Hope et al 2001), but largerscale patterns may also emerge associated with gradual changes in the relative contribution of groundwater that occur along a river continuum (Jones and Mulholland 1998b).…”

Section: Distal Controlsmentioning

confidence: 99%

“…While spatial heterogeneity created by hydrology is apparent in many studies, temporal changes in flow can also have pronounced effects on delivery and/or persistence of CH 4 . Inverse relationships between discharge and CH 4 concentration exist among vastly different sites, from small headwater catchments in peat-dominated landscapes (Hope et al 2001, Dinsmore et al 2013 to large temperate and tropical rivers (Koné et al 2010, Anthony et al 2012. Low concentrations during high-flow periods have been attributed to precipitation or snowmelt-driven dilution, increased gas exchange, and reduced sediment-water contact.…”

Section: Distal Controlsmentioning

confidence: 99%

The ecology of methane in streams and rivers: patterns, controls, and global significance

Stanley¹,

Casson²,

Christel³

et al. 2015

Ecological Monographs

168

315

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Growing awareness of ongoing and rapid changes in Earth's carbon cycle is motivating a new era of research aimed at improving our understanding of ecosystems as both responders to, and drivers of larger-scale biogeochemical dynamics. In the case of streams and rivers, this has often taken the form of elucidating their role as processors of organic carbon (OC), a capacity that far exceeds their meager size and significantly influences the export of continental OC to marine environments (Cole et al. 2007, Battin et al. 2009, Aufdenkampe et al. 2011). Amplified OC processing has been inferred from observations of smaller export loads relative to inputs, rates of ecosystem respiration that exceed gross primary production, and/or occurrence of supersaturated concentrations of the products of OC decomposition, namely, carbon dioxide (CO 2) and methane (CH 4).

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“…However, in the Bykovskaya and Olenekskaya channels, methane concentrations did not change significantly along the flow distances. Based on the work of Anthony et al (2012) and de Angelis and Scranton (1993), we propose a simple box model to budget the methane fluxes in the Lena. For a certain section of the river, the methane flowing out (F out ) is the sum of the methane flowing into this section (F in ), the losses due to diffusive flux (F diff ), the microbial oxidation (F oxid ) and additional methane supply (F supply ) from methane production in the river sediment or lateral input from creeks draining into the river.…”

Section: Processes Within the Rivermentioning

confidence: 99%

“…The fluxes in and out of a certain river section are calculated by multiplying the measured concentrations with the respective discharge (Anthony et al, 2012). The areal diffusive flux is calculated by multiplying the surface area of this river section (data from with the calculated diffusive flux.…”

Section: Processes Within the Rivermentioning

confidence: 99%

Distribution of methane in the Lena Delta and Buor-Khaya Bay, Russia

Bussmann

2013

Biogeosciences

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The Lena River is one of the largest Russian rivers draining into the Laptev Sea. The permafrost areas surrounding the Lena are predicted to thaw at increasing rates due to global temperature increases. With this thawing, large amounts of carbon – either organic or in the gaseous forms carbon dioxide and methane – will reach the waters of the Lena and the adjacent Buor-Khaya Bay (Laptev Sea). Methane concentrations and the isotopic signal of methane in the waters of the Lena Delta and estuary were monitored from 2008 to 2010. Creeks draining from permafrost soils produced hotspots for methane input into the river system (median concentration 1500 nM) compared with concentrations of 30–85 nM observed in the main channels of the Lena. No microbial methane oxidation could be detected; thus diffusion is the main process of methane removal. We estimated that the riverine diffusive methane flux is 3–10 times higher than the flux from surrounding terrestrial environment. To maintain the observed methane concentrations in the river, additional methane sources are necessary. The methane-rich creeks could be responsible for this input.

In the estuary of Buor-Khaya Bay, methane concentrations decreased to 26–33 nM. However, within the bay no consistent temporal and spatial pattern could be observed. The methane-rich waters of the river were not diluted with marine water because of a strong stratification of the water column. Thus, methane is released from the estuary and from the river mainly by diffusion into the atmosphere

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Methane dynamics in the Willamette River, Oregon

Cited by 23 publications

References 47 publications

The ecology of methane in streams and rivers: patterns, controls, and global significance

The ecology of methane in streams and rivers: patterns, controls, and global significance

The ecology of methane in streams and rivers: patterns, controls, and global significance

Distribution of methane in the Lena Delta and Buor-Khaya Bay, Russia

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