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Effects of elevated carbon dioxide o...

McLain, Jean Elizabeth-Triol.

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Effects of elevated carbon dioxide on oxidation of methane in soils.

紀錄類型:	書目-語言資料,印刷品 : Monograph/item
正題名/作者:	Effects of elevated carbon dioxide on oxidation of methane in soils./
作者:	McLain, Jean Elizabeth-Triol.
面頁冊數:	168 p.
附註:	Source: Dissertation Abstracts International, Volume: 64-01, Section: B, page: 0043.
Contained By:	Dissertation Abstracts International64-01B.
標題:	Agriculture, Soil Science. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3077146
ISBN:	0493975632

Effects of elevated carbon dioxide on oxidation of methane in soils.
McLain, Jean Elizabeth-Triol.

Effects of elevated carbon dioxide on oxidation of methane in soils. - 168 p.

Source: Dissertation Abstracts International, Volume: 64-01, Section: B, page: 0043.

Thesis (Ph.D.)--Duke University, 2002.

Oxidation of atmospheric CH4 by unsaturated soils is an important process in the global carbon cycle. Sustained increases in atmospheric CO 2 concentration, observed over the past century and projected to continue into the next, may reduce net soil methane consumption. This study determined the effects of elevated atmospheric CO2 on net methane oxidation in a temperate forest soil, elucidated the controlling mechanisms behind altered methane consumption, and established whether changes in methane cycling under elevated CO2 were induced by physical or biological variations. Belowground factors impacting soil CH4 consumption were investigated at the Free Air Carbon Transfer and Storage (FACTS)-I site in the Duke Forest, NC, in which plots have been exposed to ambient (370ppm) or elevated (ambient + 200ppm) CO2 since August 1996. CH4 fluxes at the soil surface, porespace concentrations of CH4, O2, and CO 2, and soil moisture, temperature, and pH were regularly measured over 24 months. Porespace CH4 concentrations and surface CH4 flux measurements confirmed that methanotrophic activity was depleting CH 4 in the upper soil layers, creating a concentration gradient that mobilized CH4 from the atmosphere into the soil. Under elevated CO2 , porespace CH4 was 25–30% higher in the upper 70cm of soils, CH4 fluxes from the atmosphere into soil were diminished by &sim;25%, and net methanotroph activity measured <italic>in vitro</italic> was reduced by &sim;15%. In addition, volumetric soil moisture was greater by up to 40% during some seasons, perhaps caused by reduced evaporation from the soil surface that resulted from increased standing litter and, to a lesser extent, by small-scale topographic variations that existed before fumigation began. Statistical modeling indicated that soil moisture strongly predicted variability in surface CH4 fluxes and that soil CO2 and soil moisture both predicted variability in soil CH4. Gas transport modeling showed that nearly all of the CH4 consumption occurred in the top 30cm and that the strongest inhibition in soil CH4 oxidation was localized in the top 10cm of soils, where a 35% reduction in the CH 4 sink under elevated atmospheric CO2 was calculated. Physical model results indicated that soil moisture increases strongly controlled the reduced methane oxidation, but also suggested that >50% of the inhibition in methane consumption was attributable to altered biological processes in elevated CO2 plots.

ISBN: 0493975632Subjects--Topical Terms:

1017824
Agriculture, Soil Science.

Effects of elevated carbon dioxide on oxidation of methane in soils.
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