CH4 transport mechanisms via rice plants: a new approach using isotopic fractionation of 13C-CH4

Research Project

Project/Area Number	25660200
Research Category	Grant-in-Aid for Challenging Exploratory Research
Allocation Type	Multi-year Fund
Research Field	Agricultural environmental engineering/Agricultural information engineering
Research Institution	National Institute for Agro-Environmental Sciences
Principal Investigator	TOKIDA Takeshi 独立行政法人農業環境技術研究所, その他部局等, 研究員 (20585856)
Project Period (FY)	2013-04-01 – 2015-03-31
Project Status	Completed (Fiscal Year 2014)
Budget Amount *help	¥3,900,000 (Direct Cost: ¥3,000,000、Indirect Cost: ¥900,000) Fiscal Year 2014: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000) Fiscal Year 2013: ¥2,080,000 (Direct Cost: ¥1,600,000、Indirect Cost: ¥480,000)
Keywords	メタン / 水田 / イネ / 炭素安定同位体比 / ガス輸送 / 移流 / 拡散
Outline of Final Research Achievements	Rice paddies represent one of the largest anthropogenic sources of atmospheric CH4. Methane is produced by methanogens in anoxic soil and released into the atmosphere mainly via aerenchyma tissue of rice plants; however physical mechanisms of the emissions remain unclear. In this study CH4 emission was measured at a farmer's rice paddy, showing a large (>2-3 folds) diurnal variation in CH4 emissions after the middle of the growth season. The larger emissions during the daylight hours accompanied relatively heavier CH4 (enriched in 13C) while smaller emissions during the nighttime were characterized with lighter (less 13C) CH4. These results suggest occurrence of and shift in different transport mechanisms of CH4 through rice plants.