title: Preliminary report on methane emissions from the Three Gorges Reservoir in the summer drainage period.
abstract: Recently reported summertime methane (CH4) emissions (6.7 +/- 13.3 mg CH4/(m2 x hr)) from newly created marshes in the drawdown area of the Three Gorges Reservoir (TGR), China have triggered broad concern in academic circles and among the public. The CH4 emissions from TGR water surfaces and drawdown areas were monitored from 3rd June to 16th October 2010 with floating and static chambers and gas chromatography. The average CH4 emission flux from permanently flooded areas in Zigui, Wushan and Yunyang Counties was (0.33 +/- 0.09) mg CH4/(m2 x hr). In half of these hottest months of the year, the wilderness, cropland and deforested drawdown sites were aerobic and located above water level, and the CH4 emissions were very small, ranging from a sink at 0.12 mg CH4/(m2 x hr) to a source at 0.08 mg CH4/(m2 x hr) except for one mud-covered site after flood. Mean CH4 emission in flooded drawdown sites was 0.34 mg CH4/(m2 x hr). The emissions from the rice paddy sites in the drawdown area were averaged at (4.86 +/- 2.31) mg CH4/(m2 x hr). Excepting the rice-paddy sites, these results show much lower emission levels than previously reported. Our results indicated considerable spatial and temporal variation in CH4 emissions from the TGR. Human activities and occasional events, such as flood, may also affect emission levels. Long-term CH4 measurements and modeling in a large region are necessary to accurately estimate greenhouse gas emissions from the TGR.
authors.affiliation: State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China. lu_fei@yahoo.cn
authors.forename: Fei
authors.initials: F
authors.lastname: Lu
authors.forename: Le
authors.initials: L
authors.lastname: Yang
authors.forename: Xiaoke
authors.initials: X
authors.lastname: Wang
authors.forename: Xiaonan
authors.initials: X
authors.lastname: Duan
authors.forename: Yujing
authors.initials: Y
authors.lastname: Mu
authors.forename: Wenzhi
authors.initials: W
authors.lastname: Song
authors.forename: Feixiang
authors.initials: F
authors.lastname: Zheng
authors.forename: Junfeng
authors.initials: J
authors.lastname: Niu
authors.forename: Lei
authors.initials: L
authors.lastname: Tong
authors.forename: Hua
authors.initials: H
authors.lastname: Zheng
authors.forename: Yongjuan
authors.initials: Y
authors.lastname: Zhou
authors.forename: Jiangxiao
authors.initials: J
authors.lastname: Qiu
authors.forename: Zhiyun
authors.initials: Z
authors.lastname: Ouyang
mesh_terms: D002681:China; D002849:Chromatography, Gas; D008697:Methane / Q000032:analysis*; D045483:Rivers; D012621:Seasons; D014874:Water Pollutants, Chemical / Q000032:analysis*; D053833:Wetlands
chemical_list: D014874:Water Pollutants, Chemical; D008697:Methane