Methane Fluxes of Vegetated Areas in Natural Freshwater Ecosystems: Assessments and Global Significance

Bodmer, Pascal; Vroom, Renske; Stepina, Tatiana; Giorgio, Paul del; Kosten, Sarian

doi:10.31223/x5nd0f

Cited by 9 publications

(9 citation statements)

References 92 publications

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“…Vegetation can also regulate CO 2 and CH 4 in aquatic systems (Bodmer et al 2021; Bastviken et al 2023). We found that the percent of the waterbody covered with floating vegetation related positively to both p CO 2 and p CH 4 and the percent of the waterbody area covered with emergent vegetation was positively related to p CO 2 .…”

Section: Discussionmentioning

confidence: 99%

Spatial and temporal variability in summertime dissolved carbon dioxide and methane in temperate ponds and shallow lakes

Ray

Holgerson

Andersen

et al. 2023

Limnology & Oceanography

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Small waterbodies have potentially high greenhouse gas emissions relative to their small footprint on the landscape, although there is high uncertainty in model estimates. Scaling their carbon dioxide (CO2) and methane (CH4) exchange with the atmosphere remains challenging due to an incomplete understanding and characterization of spatial and temporal variability in CO2 and CH4. Here, we measured partial pressures of CO2 (pCO2) and CH4 (pCH4) across 30 ponds and shallow lakes during summer in temperate regions of Europe and North America. We sampled each waterbody in three locations at three times during the growing season, and tested which physical, chemical, and biological characteristics related to the means and variability of pCO2 and pCH4 in space and time. Summer means of pCO2 and pCH4 were inversely related to waterbody size and positively related to floating vegetative cover; pCO2 was also positively related to dissolved phosphorus. Temporal variability in partial pressure in both gases weas greater than spatial variability. Although sampling on a single date was likely to misestimate mean seasonal pCO2 by up to 26%, mean seasonal pCH4 could be misestimated by up to 64.5%. Shallower systems displayed the most temporal variability in pCH4 and waterbodies with more vegetation cover had lower temporal variability. Inland waters remain one of the most uncertain components of the global carbon budget; understanding spatial and temporal variability will ultimately help us to constrain our estimates and inform research priorities.

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Section: Discussionmentioning

confidence: 99%

Spatial and temporal variability in summertime dissolved carbon dioxide and methane in temperate ponds and shallow lakes

Ray

Holgerson

Andersen

et al. 2023

Limnology & Oceanography

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“…The final and most profound knowledge gap in the collection of flux data is the absence of measurements of plant-mediated emissions. Plant-mediated fluxes can account for a substantial fraction of total emissions from wetlands and shallow lake habitats (Bodmer et al, 2021) but the contribution of this pathway is unknown in fluvial systems. Indeed, we did not include plant mediated fluxes in GRiMe DB because we encountered only two papers that had explicitly quantified this pathway in streams .…”

Section: How: Methodological Considerationsmentioning

confidence: 99%

“…Although aquatic macrophytes are sparse or absent from many streams and rivers, they can be abundant in low-gradient, low-disturbance environments (Riis and Biggs, 2003;Gurnell et al, 2010) where diffusive fluxes would be constrained by low gas exchange rates. Sediment trapping and venting by macrophytes enhances both methanogenesis and methane emission in these systems , but the significance of such processes and the contribution of plant-mediated fluxes at larger spatial scales remain to be determined for fluvial systems (Bodmer et al, 2021).…”

Section: How: Methodological Considerationsmentioning

confidence: 99%

GRiMeDB: The global river database of methane concentrations and fluxes

Stanley

Loken

Casson

et al. 2022

Preprint

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Abstract. Despite their small spatial extent, fluvial ecosystems play a significant role in processing and transporting carbon in aquatic networks, which results in substantial emission of methane (CH4) to the atmosphere. For this reason, considerable effort has been put into identifying patterns and drivers of CH4 concentrations in streams and rivers and estimating fluxes to the atmosphere across broad spatial scales. Yet progress toward these ends has been slow because of pronounced spatial and temporal variability of lotic CH4 concentrations and fluxes and by limited data availability across diverse habitats and physicochemical conditions. To address these challenges, we present the first comprehensive database of CH4 concentrations and fluxes for fluvial ecosystems along with broadly relevant and concurrent physical and chemical data. The Global River Methane database (GriMeDB; https://doi.org/10.6073/pasta/b7d1fba4f9a3e365c9861ac3b58b4a90) includes 24,024 records of CH4 concentration and 8,205 flux measurements from 5,037 unique sites that were extracted from publications, reports, data repositories, and other outlets published between 1973 and 2021. GriMeDB also includes 17,655 and 8,409 concurrent measurements of concentrations and 4,444 and 1,521 of fluxes for CO2 and nitrous oxide (N2O) respectively. Most observations are date-specific (i.e., not site averages) and many are supported by data for 12 physicochemical variables and 6 site variables. Site variables include codes to characterize marginal channel types (e.g., springs, ditches) and/or presence of human disturbance (e.g., point source inputs, upstream dams). Overall, observations in GRiMeDB encompass a broad range of the climatic, biological, and physical conditions that occur among world river basins, although some geographic gaps remain (e.g., arid regions, tropical regions, high latitudes and altitude systems). The global median CH4 concentration (0.20 μmol L-1) and diffusive flux (0.44 mmol m-2 d-1) in GRiMeDB are lower than estimates from past, site-averaged compilations, although ranges and standard deviations are greater from this larger and more temporally-resolved database. Available flux data are dominated by diffusive measurements despite the recognized importance of ebullitive and plant-mediated CH4 fluxes. Despite these limitations, GriMeDB provides a comprehensive and cohesive resource for examining relationships between CH4 and environmental drivers, estimating the contribution of fluvial ecosystems to CH4 emissions, and to contextualize site-based investigations.

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“…Existing reviews on the role of macrophytes in regulating CH 4 dynamics mainly focus on anaerobic processes and emergent species (Laanbroek 2010; Carmichael et al 2014; Bodmer et al 2021). Here, we propose that freshwater and marine submerged macrophytes also contribute to OMP and thus their contribution to overall CH 4 fluxes should be taken into account.…”

Section: Figmentioning

confidence: 99%

Potential role of submerged macrophytes for oxic methane production in aquatic ecosystems

Hilt

Grossart

Mcginnis

et al. 2022

Limnology & Oceanography

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Methane (CH4) from aquatic ecosystems contributes to about half of total global CH4 emissions to the atmosphere. Until recently, aquatic biogenic CH4 production was exclusively attributed to methanogenic archaea living under anoxic or suboxic conditions in sediments, bottom waters, and wetlands. However, evidence for oxic CH4 production (OMP) in freshwater, brackish, and marine habitats is increasing. Possible sources were found to be driven by various planktonic organisms supporting different OMP mechanisms. Surprisingly, submerged macrophytes have been fully ignored in studies on OMP, yet they are key components of littoral zones of ponds, lakes, and coastal systems. High CH4 concentrations in these zones have been attributed to organic substrate production promoting classic methanogenesis in the absence of oxygen. Here, we review existing studies and argue that, similar to terrestrial plants and phytoplankton, macroalgae and submerged macrophytes may directly or indirectly contribute to CH4 formation in oxic waters. We propose several potential direct and indirect mechanisms: (1) direct production of CH4; (2) production of CH4 precursors and facilitation of their bacterial breakdown or chemical conversion; (3) facilitation of classic methanogenesis; and (4) facilitation of CH4 ebullition. As submerged macrophytes occur in many freshwater and marine habitats, they are important in global carbon budgets and can strongly vary in their abundance due to seasonal and boom‐bust dynamics. Knowledge on their contribution to OMP is therefore essential to gain a better understanding of spatial and temporal dynamics of CH4 emissions and thus to substantially reduce current uncertainties when estimating global CH4 emissions from aquatic ecosystems.

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Methane Fluxes of Vegetated Areas in Natural Freshwater Ecosystems: Assessments and Global Significance

Cited by 9 publications

References 92 publications

Spatial and temporal variability in summertime dissolved carbon dioxide and methane in temperate ponds and shallow lakes

Spatial and temporal variability in summertime dissolved carbon dioxide and methane in temperate ponds and shallow lakes

GRiMeDB: The global river database of methane concentrations and fluxes

Potential role of submerged macrophytes for oxic methane production in aquatic ecosystems

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