Variable promotion of algae and macrophyte organic matter on methanogenesis in anaerobic lake sediment

Wang, Tong; Zhumabieke, Maidina; Zhang, Nan; Liu, Cheng; Zhong, Jicheng; Liao, Qianjiahua; Zhang, Lei

doi:10.1016/j.envres.2023.116922

Cited by 8 publications

(3 citation statements)

References 55 publications

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“…Although there were marginal increases in the relative abundance of polysaccharides after wetland loss, the most pronounced differences in organic matter chemistry were the consistent decreases in lignin: polysaccharide ratios with depth in both marshes and ponds (Figure 3a, Supporting Information S1), indicating surface soils of the vegetated marshes and open water ponds contain more easily degradable organics. In anoxic organic soils, CH 4 production increases with the availability of easily degradable carbon sources like polysaccharides, root exudates, or organic matter deposited from decomposing phytoplankton (Bridgham et al, 2013;King et al, 2002;Wang et al, 2023;Yagi & Minami, 1990;Yavitt et al, 1997). Lowerthan-expected CH 4 production rates relative to CO 2 -like we observed at depth-have been attributed to the use of organics (i.e., phenolics) as a terminal electron acceptors, and a buildup of fermentation products (e.g., CO 2 , acetate, H 2 ) without conversion to CH 4 by methanogens (Bridgham et al, 2013;Miller et al, 2015;Ye et al, 2012).…”

Section: Mechanisms Controlling Greenhouse Gas Production In Vegetate...mentioning

confidence: 99%

Vegetation Loss Following Vertical Drowning of Mississippi River Deltaic Wetlands Leads to Faster Microbial Decomposition and Decreases in Soil Carbon

Creamer,

Waldrop,

Stagg

et al. 2024

JGR Biogeosciences

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Wetland ecosystems hold nearly a third of the global soil carbon pool, but as wetlands rapidly disappear the fate of this stored soil carbon is unclear. The aim of this study was to quantify and then link potential rates of microbial decomposition after vertical drowning of vegetated tidal marshes in coastal Louisiana to known drivers of anaerobic decomposition altered by vegetation loss. Profiles of potential CH4 and CO2 production (surface to 60 cm deep) were measured during anaerobic incubations, organic matter chemistry was assessed with infrared spectroscopy, and soil porewater nutrients and redox potentials were measured in the field along a chronosequence of wetland loss. After vertical drowning, pond soils had lower redox potentials, higher pH values, lower soil carbon and nitrogen concentrations, lower lignin: polysaccharide ratios, more NH4+ and PO43−, and higher rates of potential CO2 release than vegetated marsh soils. Potential CH4 production was similar in vegetated marshes and open water ponds, with depth‐dependent decreases in CH4 production as soil carbon concentrations increased. In these anoxic soils, vegetation loss exerts a primary control on decomposition rates because flooding drives sustained increases in porewater nutrient availability (NH4+ and PO43, dissolved organic carbon) and decreases in redox potential (from −150 to −500 mV) that lead to higher potential CO2 fluxes within a few years. Without new carbon inputs following wetland loss, the sustained decomposition in open water ponds may lead to losses of stored soil carbon and could influence global carbon budgets.

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Section: Mechanisms Controlling Greenhouse Gas Production In Vegetate...mentioning

confidence: 99%

Vegetation Loss Following Vertical Drowning of Mississippi River Deltaic Wetlands Leads to Faster Microbial Decomposition and Decreases in Soil Carbon

Creamer,

Waldrop,

Stagg

et al. 2024

JGR Biogeosciences

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“…This could suggest a higher contribution of the hydrogenotrophic methanogenesis pathway compared to the acetoclastic pathway in the clear-water ponds where organic matter for methanogenesis was mainly related to macrophytes rather than phytoplankton. Based on gene expression during incubations (qPCR), Wang et al, (2023) suggested that macrophyte organic carbon stimulated acetoclastic methanogenesis pathway compared to phytoplankton organic matter in lakes Chaohu and Taihu in China. The pattern of δ 13 C-CH4 data in the four urban ponds of the city of Brussels suggests the opposite pattern, with macrophyte organic carbon stimulating the hydrogenotrophic methanogenesis pathway.…”

Section: Methanogenesis Pathway Inferred From δ 13 C-ch4 In Bubblesmentioning

confidence: 99%

Comment on egusphere-2024-1315

2024

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Section: Methanogenesis Pathway Inferred From δ 13 C-ch4 In Bubblesmentioning

confidence: 99%

Methane, carbon dioxide and nitrous oxide emissions from two clear-water and two turbid-water urban ponds in Brussels (Belgium)

Bauduin,

Gypens,

Borges

2024

Preprint

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Abstract. Shallow ponds can exist in a clear-water state dominated by macrophytes or a turbid-water state dominated by phytoplankton, but it is unclear if these two states affect differently carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) emissions to the atmosphere. Two clear-water urban ponds (Silex and Tenreuken) dominated by macrophytes, and two turbid-water urban ponds (Leybeek and Pêcheries) dominated by phytoplankton, in the city of Brussels (Belgium), were sampled 46 times between June 2021 and December 2023 to measure the partial pressure of CO2 (pCO2), dissolved CH4 concentration, N2O saturation level (%N2O), and ancillary variables. CH4 ebullitive fluxes were also measured in the four ponds during 8 deployments, totally 48 days of cumulated measurements. The 13C/12C ratio of CH4 (δ13C-CH4) was measured in bubbles from the sediment and in water to decipher the pathway of sedimentary methanogenesis (acetoclastic or hydrogenotrophic) and quantify methane oxidation (MOX) in the water column. The pCO2 and CH4 values in the sampled urban ponds correlated with precipitation and water temperature, respectively. The %N2O values did not correlate with dissolved inorganic nitrogen (DIN) nor other variables for the individual ponds, but a positive relation to DIN emerged from the combined data-set for the four ponds. The sampled turbid-water and clear-water ponds did not show differences in terms of diffuse emissions of CO2 and N2O. Clear-water ponds exhibited higher values of annual ebullitive CH4 fluxes compared to turbid-water ponds, most probably in relation to the delivery to sediments of organic matter from macrophytes. At seasonal scale, CH4 fluxes between the surface of the ponds and the atmosphere exhibited a temperature dependence in all four ponds, with ebullitive CH4 fluxes having a stronger dependence to temperature than diffusive CH4 fluxes. The temperature sensitivity of ebullitive CH4 fluxes was different among the four ponds and decreased with increasing water depth. During summer 2023, hydrogenotrophic methanogenesis pathway seemed to dominate in clear-water ponds and acetoclastic methanogenesis pathway seemed to dominate in turbid-water ponds, as indicated by the δ13C-CH4 values of bubbles sampled by physically perturbing sediments. The δ13C-CH4 values of bubbles sampled during bubble trap deployments in 2021–2023 indicated a seasonal shift to hydrogenotrophic methanogenesis pathway in fall compared to spring and summer, when acetoclastic methanogenesis pathway seemed to dominate. The δ13C-CH4 of dissolved CH4 indicated higher rates of MOX in turbid-water ponds compared to clear-water ponds, with an overall positive correlation with total suspended matter (TSM) and Chlorophyll-a (Chl-a) concentrations. The presence of suspended particles putatively enhanced MOX by reducing light inhibition of MOX and/or by serving as substrate for fixed methanotrophic bacteria in the water column. Total CH4 emissions in CO2 equivalents either equalized or exceeded those of CO2 in most ponds, while N2O emissions were negligible compared to the other two greenhouse gases (GHGs). Total annual GHG emissions in CO2 equivalents from all four ponds increased from 2022 to 2023 due to higher CO2 diffusive fluxes, likely driven by higher annual precipitation in 2023 compared to 2022, possibly in response to the intense El Niño event of 2023.

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Variable promotion of algae and macrophyte organic matter on methanogenesis in anaerobic lake sediment

Cited by 8 publications

References 55 publications

Vegetation Loss Following Vertical Drowning of Mississippi River Deltaic Wetlands Leads to Faster Microbial Decomposition and Decreases in Soil Carbon

Vegetation Loss Following Vertical Drowning of Mississippi River Deltaic Wetlands Leads to Faster Microbial Decomposition and Decreases in Soil Carbon

Comment on egusphere-2024-1315

Methane, carbon dioxide and nitrous oxide emissions from two clear-water and two turbid-water urban ponds in Brussels (Belgium)

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