Author
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Parkin, Timothy |
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Submitted to: Soil Biology and Biochemistry
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 3/1/2000 Publication Date: N/A Citation: N/A Interpretive Summary: Soils play an important role in the production and consumption of greenhouse gasses. Methane is a greenhouse gas that is actively cycled in soils. One group of soil bacteria is responsible for producing methane, while a different group of bacteria is responsible for consuming methane. Thus, the net contribution of methane to the atmosphere from soil is a result of these two competing processes. To more fully understand the impact human activity has on methane flux from soils, we need better tools to study the activities of these bacteria. This study was performed in order to evaluate the abilities of a variety of gaseous compounds to inhibit either methane consumption of methane production activity in soil. We determined that two of these compounds (acetylene and methyl fluoride) were very effective at inhibiting methane consumption, but did not effect methane production. On the other hand, a different compound (methyl chloride) could inhibit methane production, but did not inhibit methane consumption. By using these compounds to selectively inhibit either methane production or methane consumption, scientists can now determine the important factors controlling these two processes in the soil. Technical Abstract: Biological methane production is an anaerobic process, while methane consumption occurs predominately under aerobic conditions; however, both processes can occur simultaneously in soil. Thus, field measurements of methane flux reflect the net result of both consumption and production reactions. To increase our understanding of the factors controlling methane cycling in soil, techniques to determine gross rates of methane production and consumption are needed. Specific inhibitors of either the production or consumption processes of methane offer the opportunity for assessing the rates of these two processes independently. The objective of this work was to identify potential gaseous inhibitors of either methanotrophy or methanogenesis, and to evaluate the effect of inhibitor concentration on these two processes. For these studies sieved soil (0.5 cm mesh) was treated with a variety of compounds including acetylene (C2H2), ethylene (C2H4), ethane (C2H6), methyl chloride (CH3Cl) and methyl fluoride (CH3F). Each experiment consisted of six different treatments which included sterile soil, untreated soil and soil with test compound concentrations of 0.001% , 0.01%, 0.1% and 1%. Incubations were conducted under both aerobic and anaerobic conditions. Complete inhibition of methane oxidation was attained at 0.01% C2H2 and 0.1% CH3F headspace concentration. All other test compounds exhibited only partial inhibition of methane oxidation at their maximum test concentrations. Methyl fluoride at 0.1% did not significantly influence methane production. Near complete inhibition of methane production was attained at 1% C2H2 and CH3Cl. |
