Microbial Removal of Atmospheric Carbon Tetrachloride in Bulk Aerobic Soils

Mendoza, Yudania; Goodwin, Kelly D.; Happell, James D.

doi:10.1128/aem.05341-11

Cited by 7 publications

(5 citation statements)

References 63 publications

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“…With a calculated degradation time of ∼ 2600 yr, hydrolysis does not provide a removal rate that could balance air-sea exchange (e.g., Yvon-Lewis and Jeffers et al, 1994), so that leaves us with invoking biological or other unknown mechanisms removing CCl 4 in well oxygenated surface waters. This is an area that requires further investigation, as there is no direct evidence to date for such pathways in the ocean, although there is evidence for microbial removal of CCl 4 in well oxygenated soils (e.g., Mendoza et al, 2011).…”

Section: Explaining the Observed Undersaturationsmentioning

confidence: 99%

A comprehensive estimate for loss of atmospheric carbon tetrachloride (CCl<sub>4</sub>) to the ocean

et al. 2016

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Abstract. Extensive undersaturations of carbon tetrachloride (CCl 4 ) in Pacific, Atlantic, and Southern Ocean surface waters indicate that atmospheric CCl 4 is consumed in large amounts by the ocean. Observations made on 16 research cruises between 1987 and 2010, ranging in latitude from 60 • N to 77 • S, show that negative saturations extend over most of the surface ocean. Corrected for physical effects associated with radiative heat flux, mixing, and air injection, these anomalies were commonly on the order of −5 to −10 %, with no clear relationship to temperature, productivity, or other gross surface water characteristics other than being more negative in association with upwelling. The atmospheric flux required to sustain these undersaturations is 12.4 (9.4-15.4) Gg yr −1 , a loss rate implying a partial atmospheric lifetime with respect to the oceanic loss of 183 (147-241) yr and that ∼ 18 (14-22) % of atmospheric CCl 4 is lost to the ocean. Although CCl 4 hydrolyzes in seawater, published hydrolysis rates for this gas are too slow to support such large undersaturations, given our current understanding of air-sea gas exchange rates. The even larger undersaturations in intermediate depth waters associated with reduced oxygen levels, observed in this study and by other investigators, strongly suggest that CCl 4 is ubiquitously consumed at mid-depth, presumably by microbiota. Although this subsurface sink creates a gradient that drives a downward flux of CCl 4 , the gradient alone is not sufficient to explain the observed surface undersaturations. Since known chemical losses are likewise insufficient to sustain the observed undersaturations, this suggests a possible biological sink for CCl 4 in surface or near-surface waters of the ocean. The total atmospheric lifetime for CCl 4 , based on these results and the most recent studies of soil uptake and loss in the stratosphere is now 32 (26-43) yr.

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Section: Explaining the Observed Undersaturationsmentioning

confidence: 99%

A comprehensive estimate for loss of atmospheric carbon tetrachloride (CCl<sub>4</sub>) to the ocean

et al. 2016

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“…Hence, the difference in uptake rates between different terrestrial biomes may be affected by the varying moisture, temperature, and organic carbon content of the terrestrial soils. It has been shown that the addition of organic carbon compounds (methanol, acetate, and succinate) significantly enhanced removal of CCl 4 in marl soils [Mendoza et al, 2011]. This may help explain why ecosystems with high carbon throughput (such as tropical/subtropical forest soils) have higher uptake rates.…”

Section: Resultsmentioning

confidence: 99%

“…There are few reported measurements on the terrestrial uptake of CCl 4 , owing to the difficulty and/or expense of conducting field measurements in representative ecosystems [Happell et al, 2014;Happell and Roche, 2003;Happell and Wallace, 1998;Liu, 2006;Mendoza et al, 2011;Rhew et al, 2008a]. Although the soil sink for CCl 4 appears to be widespread, the magnitude of uptake rates in most biomes is small, with the tropical/subtropical forests and agricultural biomes accounting for half of the global uptake rate.…”

Section: Resultsmentioning

confidence: 99%

“…Soil consumption of CCl 4 is believed to be both aerobic and biotic [ Mendoza et al ., ]. Hence, the difference in uptake rates between different terrestrial biomes may be affected by the varying moisture, temperature, and organic carbon content of the terrestrial soils.…”

Section: Resultsmentioning

confidence: 99%

“…Among the three degradation routes, the soil sink strength has the largest uncertainty. The consumption of CCl 4 in soils appears to be primarily biological and associated with aerobic bacteria (although not methanotrophs or nitrifying bacteria) [ Happell and Wallace , ; Mendoza et al ., ]. The initial estimate of the partial lifetime of CCl 4 with respect to the global soil sink was 90 (50 to 418) years, based on 348 soil gradient measurements in four terrestrial biomes and applied to seven biomes total [ Happell and Roche , ].…”

Section: Introductionmentioning

confidence: 99%

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The atmospheric partial lifetime of carbon tetrachloride with respect to the global soil sink

Rhew

Happell

2016

Geophysical Research Letters

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The magnitude of the terrestrial soil sink for atmospheric carbon tetrachloride (CCl4) remains poorly constrained, with the estimated uncertainty range of CCl4 partial lifetimes between ~110 and 910 years. Field observations are sparse, and there are uncertainties in extrapolating these results to the global scale. Here we add to the published CCl4 fluxes with additional field measurements, and we employ a land cover classification scheme based on Advanced Very High Resolution Radiometer measurements that align more closely with the measurement sites to reevaluate the global CCl4 soil sink. We calculate an updated partial lifetime of CCl4 with respect to the soil sink to be 375 (288–536) years, which is 50 to 90% longer than the most recently published best estimates of the soil sink partial lifetime (195 and 245 years). This translates into a longer overall atmospheric lifetime estimate, which is more consistent with the observed atmospheric concentration trend and interhemispheric gradient.

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Bioaugmentation

Gough¹,

Nielsen²

2016

Springer Protocols Handbooks

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Microbial Removal of Atmospheric Carbon Tetrachloride in Bulk Aerobic Soils

Cited by 7 publications

References 63 publications

A comprehensive estimate for loss of atmospheric carbon tetrachloride (CCl<sub>4</sub>) to the ocean

A comprehensive estimate for loss of atmospheric carbon tetrachloride (CCl<sub>4</sub>) to the ocean

The atmospheric partial lifetime of carbon tetrachloride with respect to the global soil sink

Bioaugmentation

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Microbial Removal of Atmospheric Carbon Tetrachloride in Bulk Aerobic Soils

Cited by 7 publications

References 63 publications

A comprehensive estimate for loss of atmospheric carbon tetrachloride (CCl&lt;sub&gt;4&lt;/sub&gt;) to the ocean

A comprehensive estimate for loss of atmospheric carbon tetrachloride (CCl&lt;sub&gt;4&lt;/sub&gt;) to the ocean

The atmospheric partial lifetime of carbon tetrachloride with respect to the global soil sink

Bioaugmentation

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Product

Resources

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A comprehensive estimate for loss of atmospheric carbon tetrachloride (CCl<sub>4</sub>) to the ocean

A comprehensive estimate for loss of atmospheric carbon tetrachloride (CCl<sub>4</sub>) to the ocean