Soil environmental variables affecting the flux of methane from a range of forest, moorland and agricultural soils

MacDonald, Jannette; Skiba, U.; Sheppard, Lucy J.; Hargreaves, K. J.; Smith, K. A.; Fowler, D.

doi:10.1007/bf00000898

Cited by 80 publications

(54 citation statements)

References 40 publications

(46 reference statements)

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“…Calculations based on maintenance energy requirements suggest that methanotrophic bacteria cannot survive on atmospheric CH 4 without a more efficient CH 4 -oxidizing system (6). However, soil methanotrophs may not consume only atmospheric methane but also alternate substrates, such as methanol (3,13), or CH 4 produced in anaerobic soil microsites (1,7,16,22). Our present results show that the observed high-affinity activity in soil cannot in itself be taken as proof that the responsible bacteria are novel oligotrophic species with a specialized form of MMO.…”

mentioning

confidence: 62%

Starvation Alters the Apparent Half-Saturation Constant for Methane in the Type II Methanotroph Methylocystis Strain LR1

Dunfield

Conrad

2000

Appl Environ Microbiol

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When cells of a type II methanotrophic bacterium (Methylocystis strain LR1) were starved of methane, both the K m(app) and the V max(app) for methane decreased. The specific affinity (a o s ) remained nearly constant. Therefore, the decreased K m(app) in starved cells was probably not an adjustment to better utilize low-methane concentrations.Microbial oxidation of atmospheric methane (CH 4 ) takes place in most aerobic upland soils (5, 10). Because these soils exhibit a lower half-saturation constant [K m(app) ] for CH 4 than do pure cultures of methanotrophic bacteria, it has been postulated that the active bacteria are unknown species. These have been popularly dubbed "high-affinity" methane oxidizers (5, 10). Recently, a novel group of pmoA-like sequences was detected in several soils which oxidize atmospheric CH 4 (11,12), and incubation of soils under 14 CH 4 resulted in the labeling of signature phospholipid fatty acids which differed from those of known type II methanotrophs (18). It is therefore likely that as-yet-uncultured species are involved in atmospheric CH 4 uptake. However, it remains unknown whether atmospheric CH 4 oxidation is limited to particular species and whether these possess a specialized high-affinity CH 4 oxidation enzyme.We previously demonstrated that high-affinity CH 4 oxidation is probably not limited to uncultured methanotrophic groups. We enriched a methane-oxidizing bacterium (strain LR1) from an organic soil and identified it based on 16S rDNA, pmoA, and mxaF gene sequences as a type II methanotrophic species of the Methylosinus/Methylocystis cluster (8). Mixed cultures containing strain LR1, when grown under Ͻ275 ppm volume CH 4 , had a low K m(app) for CH 4 (56 to 188 nM) similar to the value measured in soil. This increased to Ͼ1 M when cells were grown under Ͼ1% CH 4 . In the present study, we investigated the kinetics of the isolated bacterium (culture is available upon request). Instead of the time-consuming process of growing the organism under low CH 4 mixing ratios, we tested the effect of starving cells of CH 4 .Kinetics of strain LR1. Culture was grown in liquid nitratemineral salts (NMS) medium (8) under 10% CH 4 . Purity was controlled microscopically and by plating onto NMS agar, R2A agar, 10% strength Nutrient Agar, and 10% strength AC Broth (Difco). After 1 to 2 months, the culture was diluted to about 10 9 cells ml Ϫ1 with 0.5 mM phosphate buffer (pH 6.0), and 7.5-ml amounts were added to 13-ml serum vials. The vials were capped with sterile butyl rubber stoppers and incubated with gentle shaking (6 rpm) at 25°C without added CH 4 . After 1 to 2 weeks, some vials were injected with CH 4 to a final mixing ratio of 1% and incubated for a further 24 h ("unstarved"). Others remained without CH 4 ("starved"). Cell counts were made using a Neubauer chamber and showed that no population growth occurred during the 24-h incubation with 1% CH 4 (data not shown).For determination of kinetic properties, CH 4 was injected into these vials to final mixing ratios ranging f...

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mentioning

confidence: 62%

Starvation Alters the Apparent Half-Saturation Constant for Methane in the Type II Methanotroph Methylocystis Strain LR1

Dunfield

Conrad

2000

Appl Environ Microbiol

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“…In addition, intermediate and end products from methanotrophic ammonia oxidation (i.e. hydroxylamine and nitrite) can be toxic to methanotrophic bacteria (Bronson and Mosier, 1994;MacDonald et al, 1996;Sitaula et al, 2000). Finally, large amounts of mineral fertilizers (i.e.…”

Section: Nitrogen Deposition Factor R Nmentioning

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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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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“…They remained in position over the 4-yr study period and covered the most dominant vegetation types on the Moss: three chambers each on (1) hummocks dominated by Deschampsia and/or Eriophorum, (2) hummocks of Juncus and (3) hollows dominated by mosses. To measure fluxes a flexible, transparent, dome-shaped polyethylene lid was placed onto the chamber for approximately 60 min (MacDonald et al, 1996). Air samples (200 mL) were withdrawn via a three-way tap fitted at the side of the chamber, just after chamber closure and then approximately 30 and 60 min later (later referred to as t 0 , t 30 , t 60 ).…”

Section: Soil Greenhouse Gas Flux Measurementsmentioning

confidence: 99%

Comparison of soil greenhouse gas fluxes from extensive and intensive grazing in a temperate maritime climate

et al. 2013

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Abstract. Greenhouse gas (GHG) fluxes from a seminatural, extensively sheep-grazed drained moorland and intensively sheep-grazed fertilised grassland in South East (SE) Scotland were compared over 4 yr (2007–2010). Nitrous oxide (N2O) and methane (CH4) fluxes were measured by static chambers, respiration from soil plus ground vegetation by a flow-through chamber, and the net ecosystem exchange (NEE) of carbon dioxide (CO2) by eddy-covariance. All GHG fluxes displayed high temporal and interannual variability. Temperature, radiation, water table height and precipitation could explain a significant percentage of seasonal and interannual variations. Greenhouse gas fluxes were dominated by the net ecosystem exchange of CO2 at both sites. Net ecosystem exchange of CO2 and respiration was much larger on the productive fertilised grassland (−1567 and 7157 g CO2eq m−2 yr−1, respectively) than on the seminatural moorland (−267 and 2554 g CO2eq m−2 yr−1, respectively). Large ruminant CH4 (147 g CO2eq m−2 yr−1) and soil N2O (384 g CO2eq m−2 yr−1) losses from the grazed grassland counteracted the CO2 uptake by 34%, whereas the small N2O (0.8 g CO2eq m−2 yr−1) and CH4 (7 g CO2eq m−2 yr−1) emissions from the moorland only impacted the NEE flux by 3%. The 4-yr average GHG budget for the grazed grassland was −1034 g CO2eq m−2 yr−1 and −260 g CO2eq m−2 yr−1 for the moorland.

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Soil environmental variables affecting the flux of methane from a range of forest, moorland and agricultural soils

Cited by 80 publications

References 40 publications

Starvation Alters the Apparent Half-Saturation Constant for Methane in the Type II Methanotroph Methylocystis Strain LR1

Starvation Alters the Apparent Half-Saturation Constant for Methane in the Type II Methanotroph Methylocystis Strain LR1

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

Comparison of soil greenhouse gas fluxes from extensive and intensive grazing in a temperate maritime climate

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