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

Abstract

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 35°C. 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 35°C. 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.

Magnitudes and Drivers of Greenhouse Gas Fluxes in Floodplain Ponds During Drawdown and Inundation by the Three Gorges Reservoir

“…We sampled dissolved CH 4 from the surfaces of the Three Gorges Reservoir, only. Using these mean concentrations, the water level‐water volume relationship reported by Wang et al () for the Three Gorges region, and assuming that the water column is uniformly mixed, we can extrapolate that the Three Gorges Reservoir stores 8 ± 1 kg CH 4 during the winter, when p CH 4 and diffusive CH 4 emissions are comparatively low. By comparison, the Three Gorges Floodplain, Yangtze River, and its tributaries may store up to 3.6 ± 0.7 kg CH 4 during reservoir drawdown in August, when diffusive emissions are comparatively high, using CH 4 concentrations measured in floodplain ponds and a local tributary (Pengxi River).…”

“…Second, the fate of CH 4 stored in the large water volumes of the mainstem Three Gorges Reservoir and its submerged floodplain is unknown. Though diffusive CH 4 emissions are comparatively low from the surface of the reservoir during inundation, total water volumes increase from 17.2 km 3 during drawdown to 39.9 km 3 during this period (Wang et al, ). CH 4 can be stored at higher concentrations in the anoxic layer of vertically stratified lakes and reservoirs and then released via diffusion during periods of overturn and mixing (Beaulieu et al, ; Michmerhuizen et al, ; Riera et al, ).…”

Characterization of ultraphytoplankton pigments and functional community structure in Xiangxi Bay, China, using HPLC-CHEMTAX

“…Impoundment of the TGR has had a great impact on the ecosystem, biodiversity, and water pollution of XXB. In particular, algal blooms have been frequent since June 2003 (Lian et al 2014;Mao et al 2015), and the bay has been the subject of much research (Wang et al 2014;Yang et al 2015). The current research focuses attention on outbreaks of single-species algal blooms, and on monitoring the related environmental factors.…”

Measurement and understanding of methane emission from sewers

“…Methane (CH 4 ) is a highly potent greenhouse gas and contributes significantly to climate change (IPCC, 2006, Wang et al, 2014, Xiao et al, 2013. It displays a Lower Explosive Limit (LEL) of approximately 5% by volume (vol), and thus poses a serious safety concern (Spencer et al, 2006).…”

“…It is well known that in-sewer biological processes lead to the production and emission of hydrogen sulfide, methane and other hazardous compounds (Guisasola et al, 2008, Hvitved-Jacobsen, 2002, Wang et al, 2014. Sulfide build-up in sewers causes serious odor and corrosion problems, and incurs a large cost on the water industry due to mitigation measures and the depreciation of assets (WERF, 2007a).…”