A scalable model for methane consumption in arctic mineral soils

Oh, Youmi; Stackhouse, B. T.; Lau, Maggie C. Y.; Xu, Xiangtao; Trugman, Anna T.; Moch, Jonathan M.; Onstott, Tullis C.; Jørgensen, Christian Juncher; D’Imperio, Ludovica; Elberling, Bo; Emmerton, Craig A.; Louis, Vincent L. St.; Medvigy, D.

doi:10.1002/2016gl069049

Cited by 19 publications

(13 citation statements)

References 38 publications

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“…Priemé and Christensen, 1997) and emphasized in local mechanistic models (e.g. Oh et al, 2016). These finding suggest that the soil CH 4 sink in such ecosystems may be more sensitive to future change as a result of global warming.…”

Section: Seasonal Variabilitymentioning

confidence: 78%

“…Sabrekov et al (2016) developed a process-based model of soil CH 4 uptake that also incorporates rhizosphere methanotrophy. Oh et al (2016) developed a model (XHAM) that explicitly simulates high-affinity methanotrophy and active microbial biomass dynamics. These models are driven by highresolution local data sets, which presents challenges for conducting global simulations of soil methanotrophy because of limited availability of input data necessary to drive the models (e.g.…”

Section: Introductionmentioning

confidence: 99%

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Soil Methanotrophy Model (MeMo v1.0): a process-based model to quantify global uptake of atmospheric methane by soil

et al. 2018

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Abstract. Soil bacteria known as methanotrophs are the sole biological sink for atmospheric methane (CH 4 ), a potent greenhouse gas that is responsible for ∼ 20 % of the humandriven increase in radiative forcing since pre-industrial times. Soil methanotrophy is controlled by a plethora of factors, including temperature, soil texture, moisture and nitrogen content, resulting in spatially and temporally heterogeneous rates of soil methanotrophy. As a consequence, the exact magnitude of the global soil sink, as well as its temporal and spatial variability, remains poorly constrained. We developed a process-based model (Methanotrophy Model; MeMo v1.0) to simulate and quantify the uptake of atmospheric CH 4 by soils at the global scale. MeMo builds on previous models by Ridgwell et al. (1999) and Curry (2007) by introducing several advances, including (1) a general analytical solution of the one-dimensional diffusion-reaction equation in porous media, (2) a refined representation of nitrogen inhibition on soil methanotrophy, (3) updated factors governing the influence of soil moisture and temperature on CH 4 oxidation rates and (4) the ability to evaluate the impact of autochthonous soil CH 4 sources on uptake of atmospheric CH 4 . We show that the improved structural and parametric representation of key drivers of soil methanotrophy in MeMo results in a better fit to observational data. A global simulation of soil methanotrophy for the period 1990-2009 using MeMo yielded an average annual sink of 33.5 ± 0.6 Tg CH 4 yr −1 . Warm and semi-arid regions (tropical deciduous forest and open shrubland) had the highest CH 4 uptake rates of 602 and 518 mg CH 4 m −2 yr −1 , respectively. In these regions, favourable annual soil moisture content (∼ 20 % saturation) and low seasonal temperature variations (variations < ∼ 6 • C) provided optimal conditions for soil methanotrophy and soil-atmosphere gas exchange. In contrast to previous model analyses, but in agreement with recent observational data, MeMo predicted low fluxes in wet tropical regions because of refinements in formulation of the influence of excess soil moisture on methanotrophy. Tundra and mixed forest had the lowest simulated CH 4 uptake rates of 176 and 182 mg CH 4 m −2 yr −1 , respectively, due to their marked seasonality driven by temperature. Global soil uptake of atmospheric CH 4 was decreased by 4 % by the effect of nitrogen inputs to the system; however, the direct addition of fertilizers attenuated the flux by 72 % in regions with high agricultural intensity (i.e. China, India and Europe) and by 4-10 % in agriculture areas receiving low rates of N input (e.g. South America). Globally, nitrogen inputs reduced soil uptake of atmospheric CH 4 by 1.38 Tg yr −1 , which is 2-5 times smaller than reported previously. In addition to improved characterization of the contemporary soil sink for atmospheric CH 4 , MeMo provides an opportunity to quantify more accurately the relative importance of soil methanotrophy in the global CH 4 cycle in the past and its capaci...

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Section: Seasonal Variabilitymentioning

confidence: 78%

Section: Introductionmentioning

confidence: 99%

Soil Methanotrophy Model (MeMo v1.0): a process-based model to quantify global uptake of atmospheric methane by soil

et al. 2018

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“…Nevertheless, researchers tracked 13 C-labeled CH 4 into the DNA of bacteria that were closely related to known methanotrophs such as Methylomonas, Methylococcus, and Methylocystis/Methylosinus (Hutchens et al, 2004). In a recent study of the semiarid Wellington Caves in Australia, up to 16% of the 16S rRNA gene sequences recovered from cave soils belonged to groups of known methanotrophs (McDonough et al, 2016). The high relative abundance of methanotrophs in these systems suggests that microbially mediated CH 4 oxidation should be important in at least some caves.…”

Section: Strong Experimental Support For the Importance Of Biotic Cmentioning

confidence: 99%

Microbial contributions to subterranean methane sinks

et al. 2016

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Sources and sinks of methane (CH ) are critical for understanding global biogeochemical cycles and their role in climate change. A growing number of studies have reported that CH concentrations in cave ecosystems are depleted, leading to the notion that these subterranean environments may act as sinks for atmospheric CH . Recently, it was hypothesized that this CH depletion may be caused by radiolysis, an abiotic process whereby CH is oxidized via interactions with ionizing radiation derived from radioactive decay. An alternate explanation is that the depletion of CH concentrations in caves could be due to biological processes, specifically oxidation by methanotrophic bacteria. We theoretically explored the radiolysis hypothesis and conclude that it is a kinetically constrained process that is unlikely to lead to the rapid loss of CH in subterranean environments. We present results from a controlled laboratory experiment to support this claim. We then tested the microbial oxidation hypothesis with a set of mesocosm experiments that were conducted in two Vietnamese caves. Our results reveal that methanotrophic bacteria associated with cave rocks consume CH at a rate of 1.3-2.7 mg CH · m · d . These CH oxidation rates equal or exceed what has been reported in other habitats, including agricultural systems, grasslands, deciduous forests, and Arctic tundra. Together, our results suggest that depleted concentrations of CH in caves are most likely due to microbial activity, not radiolysis as has been recently claimed. Microbial methanotrophy has the potential to oxidize CH not only in caves, but also in smaller-size open subterranean spaces, such as cracks, fissures, and other pores that are connected to and rapidly exchange with the atmosphere. Future studies are needed to understand how subterranean CH oxidation scales up to affect local, regional, and global CH cycling.

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“…Previous studies have found that Arctic tundra ecosystems have shifted from net CO 2 sinks to sources (Belshe et al, ; Oechel et al, ); whether they behave as sinks or sources of atmospheric CH 4 largely depends on local microtopography (Jørgensen et al, ; Nauta et al, ; Oh et al, ; Tan et al, ). Minor changes in surface elevation might shift Arctic soils from sinks to sources of atmospheric CH 4 (Olivas et al, ; Zona et al, ).…”

Section: Introductionmentioning

confidence: 99%

Mechanistic Modeling of Microtopographic Impacts on CO₂ and CH₄ Fluxes in an Alaskan Tundra Ecosystem Using the CLM‐Microbe Model

Wang

Yuan

et al. 2019

J Adv Model Earth Syst

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Spatial heterogeneities in soil hydrology have been confirmed as a key control on CO 2 and CH 4 fluxes in the Arctic tundra ecosystem. In this study, we applied a mechanistic ecosystem model, CLM-Microbe, to examine the microtopographic impacts on CO 2 and CH 4 fluxes across seven landscape types in Utqiaġvik, Alaska: trough, low-centered polygon (LCP) center, LCP transition, LCP rim, high-centered polygon (HCP) center, HCP transition, and HCP rim. We first validated the CLM-Microbe model against static-chamber measured CO 2 and CH 4 fluxes in 2013 for three landscape types: trough, LCP center, and LCP rim. Model application showed that low-elevation and thus wetter landscape types (i.e., trough, transitions, and LCP center) had larger CH 4 emissions rates with greater seasonal variations than highelevation and drier landscape types (rims and HCP center). Sensitivity analysis indicated that substrate availability for methanogenesis (acetate, CO 2 + H 2 ) is the most important factor determining CH 4 emission, and vegetation physiological properties largely affect the net ecosystem carbon exchange and ecosystem respiration in Arctic tundra ecosystems. Modeled CH 4 emissions for different microtopographic features were upscaled to the eddy covariance (EC) domain with an area-weighted approach before validation against EC-measured CH 4 fluxes. The model underestimated the EC-measured CH 4 flux by 20% and 25% at daily and hourly time steps, suggesting the importance of the time step in reporting CH 4 flux. The strong microtopographic impacts on CO 2 and CH 4 fluxes call for a model-data integration framework for better understanding and predicting carbon flux in the highly heterogeneous Arctic landscape.

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A scalable model for methane consumption in arctic mineral soils

Cited by 19 publications

References 38 publications

Soil Methanotrophy Model (MeMo v1.0): a process-based model to quantify global uptake of atmospheric methane by soil

Soil Methanotrophy Model (MeMo v1.0): a process-based model to quantify global uptake of atmospheric methane by soil

Microbial contributions to subterranean methane sinks

Mechanistic Modeling of Microtopographic Impacts on CO₂ and CH₄ Fluxes in an Alaskan Tundra Ecosystem Using the CLM‐Microbe Model

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A scalable model for methane consumption in arctic mineral soils

Cited by 19 publications

References 38 publications

Soil Methanotrophy Model (MeMo v1.0): a process-based model to quantify global uptake of atmospheric methane by soil

Soil Methanotrophy Model (MeMo v1.0): a process-based model to quantify global uptake of atmospheric methane by soil

Microbial contributions to subterranean methane sinks

Mechanistic Modeling of Microtopographic Impacts on CO2 and CH4 Fluxes in an Alaskan Tundra Ecosystem Using the CLM‐Microbe Model

Contact Info

Product

Resources

About

Mechanistic Modeling of Microtopographic Impacts on CO₂ and CH₄ Fluxes in an Alaskan Tundra Ecosystem Using the CLM‐Microbe Model