Production of methyl bromide in a temperate forest soil

Varner, R. K.; White, M. L.; Mosedale, Cindy H.; Crill, Patrick

doi:10.1029/2002gl016592

Cited by 14 publications

(22 citation statements)

References 29 publications

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“…These measurements are broadly consistent with previous methyl bromide measurements from temperate forests and woodlands (Dimmer et al, 2001;Varner et al, 2003;Drewer et al, 2008;Rhew et al, 2010) and provide further comparative data for those few studies that examine methyl chloride and/or methyl iodide (Dimmer et al, 2001;Sive et al, 2007;Rhew et al, 2010) (Table 1). These measurements are broadly consistent with previous methyl bromide measurements from temperate forests and woodlands (Dimmer et al, 2001;Varner et al, 2003;Drewer et al, 2008;Rhew et al, 2010) and provide further comparative data for those few studies that examine methyl chloride and/or methyl iodide (Dimmer et al, 2001;Sive et al, 2007;Rhew et al, 2010) (Table 1).…”

Section: Discussionsupporting

confidence: 86%

“…High spatial variability in methyl halide emissions has been previously reported (Dimmer et al, 2001) although it has not always been apparent (Varner et al, 2003;Rhew et al, 2010). This study, in conjunction with previous reports (Dimmer et al, 2001;Drewer et al, 2008), provides further evidence that hot spots play a significant role in determining net forest soil fluxes of methyl chloride and methyl bromide.…”

Section: Discussionsupporting

confidence: 72%

“…The observed lack of seasonality in emissions is similar to observations by Varner et al (2003) and Drewer et al (2008) but does not reflect the observations of Rhew et al (2010) and Blei & Heal (2011) both of whom saw significant differences in litter and soil response over time with maximum net emissions (or minimum net losses) during the summer to late summer months (July and October, respectively).…”

Section: Discussioncontrasting

confidence: 65%

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Methyl chloride isotopic signatures from Irish forest soils and a comparison between abiotic and biogenic methyl halide soil fluxes

Redeker

Kalin

2011

Global Change Biology

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Forest soils demonstrate in a microcosm the difficulties that are faced in quantifying methyl halide budgets. Carbon isotopic analyses have been proposed as a potential tool to address these concerns and in this study we have measured significant enrichment of the methyl chloride 13C/12C isotopic ratio (from -40.2 +/- 0.8 parts per thousand to -33.4 +/- 7.4 parts per thousand) after 9 min chamber emplacement on local Irish forest soils. This enrichment occurred independent of direction of methyl chloride fluxes. Measurements from soil cores in a flow-through system (FTS) are comparable with chamber-based isotopic measurements and indicate that methyl chloride produced abiotically from organic soil horizons has an isotopic 13C signature of -53 +/- 49 parts per thousand, significantly less depleted than previously reported. Average net methyl chloride, methyl bromide and methyl iodide fluxes from soils (77.8 +/- 2.1, 1.25 +/- 3.63 and 0.35 +/- 2.00 mu g MeX m-2 day-1, respectively) are in line with previously reported values; however, a better understanding of spatial and temporal variability is needed for budget quantification. Methyl halide fluxes from FTS soil cores demonstrate that, on a per gram basis, most consumption occurs through biologically driven processes in the O horizon, with progressively smaller contributions in deeper horizons. Sporadic biogenic production was observed in shallow soil horizons only. Abiotic production was at most one-tenth the net biological reaction rate in the O horizon and did not appear to be significantly different from zero in lower horizons. Modelled emissions based upon observed and reported rates for production, consumption and diffusion within the soil atmosphere system are unable to replicate all observed isotopic signatures from chamber fluxes

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Section: Discussionsupporting

confidence: 86%

Section: Discussionsupporting

confidence: 72%

Section: Discussioncontrasting

confidence: 65%

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Methyl chloride isotopic signatures from Irish forest soils and a comparison between abiotic and biogenic methyl halide soil fluxes

Redeker

Kalin

2011

Global Change Biology

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“…Due to the diversity of biogenic sources, the quantification of methyl halide contribution from these sources is challenging. Known terrestrial sources include coastal salt marshes [ Drewer et al ., ; Manley et al ., ; Rhew et al ., ], mangroves [ Manley et al ., ], freshwater wetlands [ Dimmer et al ., ; Varner et al ., ], woodland and forest soils [ Drewer et al ., ; Varner et al ., ], and fungi [ Mead et al ., ; Redeker et al ., ]. Specific plants are potentially large emitters of methyl halides, including agricultural crops such as rapeseed ( Brassica napus ), cabbage ( Brassica oleracea ), rice ( Oryza sativa ), and potato tubers ( Solanum tuberosum ) [ Gan et al ., ; Harper et al ., ; Redeker et al ., ; ; Khan et al ., ; Saini et al ., ].…”

Section: Introductionmentioning

confidence: 99%

Halogen biogeochemistry of invasive perennial pepperweed (Lepidium latifolium) in a peatland pasture

et al. 2013

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[1] Perennial pepperweed (Lepidium latifolium) is a widespread invasive plant in North America. This yearlong field study at a pasture peatland infested with L. latifolium demonstrates that these plants are large emitters, on a per area basis, of methyl chloride (CH 3 Cl) and methyl bromide (CH 3 Br), compounds that contribute to the destruction of stratospheric ozone. Annually averaged net emission rates were 9.0 AE 11.8 mmol m À2 d À1 for CH 3 Cl and 460 AE 430 nmol m À2 d À1 for CH 3 Br, comparable to observed coastal salt marsh emission rates. A stable isotope tracer technique was used to distinguish between simultaneous production and consumption processes for CH 3 Cl and CH 3 Br. Over the course of the year, gross production rates for methyl halides varied widely over different life cycle stages, with the highest fluxes surprisingly occurring at senescence. Maximum emissions of CH 3 Cl and CH 3 Br occurred at midday, the time of highest solar radiation. During the growing season, methyl halide gross production rates were positively correlated with temperature and live biomass, suggesting that the production of methyl halides from L. latifolium at this time was mostly biotic. During plant senescence, the peak emissions of CH 3 Cl and CH 3 Br are unexplained but may be released from L. latifolium associated with transitions in biochemistry. Overall, these flux measurements show expected diel and growing season trends based on plant production for most of the year, overlaid by a high emission peak during senescence, suggesting that both plant biochemical shifts and varying environmental factors need to be considered as important internal and external controls on emissions.

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“…This imbalance reflects uncertainty in the magnitude of both natural sources and anthropogenic emissions. Terrestrial plant emissions probably represent the most uncertain term in the global budget, because relatively few plant species or biomes have been studied to date, and because of the challenges associated with differentiating between net and gross fluxes [ Rhew et al , 2003; Varner et al , 2003; Redeker et al , 2004; White et al , 2005].…”

Section: Introductionmentioning

confidence: 99%

2,000‐year record of atmospheric methyl bromide from a South Pole ice core

et al. 2008

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[1] This study reports measurements of methyl bromide (CH 3 Br) in air bubbles from a South Pole ice core, with gas ages covering the past two millennia. The air was extracted by mechanical shredding of the core under vacuum and the evolved gases were analyzed by gas chromatography with high resolution mass spectrometry and isotope dilution. These samples had estimated mean gas ages ranging from 160 BCE to 1860 CE. The mean CH 3 Br mixing ratio in the ice core samples was 5.39 ±.06 ppt (1s.e., n = 113). The CH 3 Br measurements from this core agree with those from a Siple Dome ice core for mean gas ages between 1671 and 1860 CE, where there is overlap between the cores. The data show no linear trend over the 2000 year period prior to industrialization. Together, Antarctic ice core and firn air measurements clearly demonstrate that the increase in atmospheric CH 3 Br during the twentieth century exceeds natural variability during the past 2000 years. There is evidence of centennial-scale variability in CH 3 Br on the order of ±10-20% that may indicate a natural climate sensitivity of the atmospheric levels of this ozone depleting substance. The analysis of CH 3 Br in additional Antarctic ice cores will be needed to confirm that the centennial-scale variability observed in this core represents a southern hemisphere atmospheric history.

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Production of methyl bromide in a temperate forest soil

Cited by 14 publications

References 29 publications

Methyl chloride isotopic signatures from Irish forest soils and a comparison between abiotic and biogenic methyl halide soil fluxes

Methyl chloride isotopic signatures from Irish forest soils and a comparison between abiotic and biogenic methyl halide soil fluxes

Halogen biogeochemistry of invasive perennial pepperweed (Lepidium latifolium) in a peatland pasture

2,000‐year record of atmospheric methyl bromide from a South Pole ice core

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