Methane formation and consumption processes in Xiangxi Bay of the Three Gorges Reservoir

 

Indoor simulation experiment was carried out to evaluate the formation and consumption rates of methane (CH4) in Xiangxi Bay of the Three Gorges Reservoir (TGR), China. The results show that both the CH4 formation and consumption rates were significantly positively correlated with temperature. CH4 efflux decreased with rising temperature due to its potential increasing oxidation rate. CH4 oxidation in surface sediments accounted for 51.8% of the total production and it even reached to 77.4% at 356C. The methane oxidation rate in water column ranged from 1.26 to 4.65 mg/(m2h), of which the average and greatest rate accounted for 46.7% and 73.9% of CH4 production respectively under the condition of 30 m water column and 356C. The methane oxidation may increase by 41.04 mg/(m2h) under average water level of TGR (160 m), and most methane resulted from sediments can be oxidized in the water column.

摘要

 

通過室內(nèi)模擬實(shí)驗(yàn)，我們對三峽庫區(qū)(TGR)湘西灣段的甲烷(CH₄)的生成和消耗速率進(jìn)行了研究。結(jié)果表明，CH₄的形成和消耗速率與溫度呈顯著的正相關(guān)。而CH₄的產(chǎn)出量由于其潛在的氧化速率的增加而降低。在表面沉積物中，CH₄氧化產(chǎn)物占總產(chǎn)物的51.8%，而且在356C的條件下這個(gè)值甚至達(dá)到了77.4%。另外,水面上甲烷的氧化速率值的范圍區(qū)間是從1.26到4.65毫克/(m2h)，其中，在30米深水下和356C的條件下，平均和最大氧化速率分別為46.7%和73.9%。因此,在三峽庫區(qū)的平均水位(160米)下，甲烷的氧化值可能增加41.04毫克/(m2h)，而在水面上，大部分由沉積物產(chǎn)生的甲烷都可以被氧化。