The characteristics and influencing factors of dissolved methane concentrations in Chongqing’s central urban area in the Three Gorges Reservoir, China
2022
Qin, Yu | Ouyang, Changyue | Gou, Yujia | Jiang, Chengyong | Li, Zhe
Methane (CH₄) emissions from reservoirs have received widespread attention. The central urban area of Chongqing in the Three Gorges Reservoir area was selected as the study area in 2020. The temporal and spatial distribution of dissolved CH₄ concentration and flux, key generation pathways, and influencing factors have been studied. The dissolved CH₄ concentration in low-water-level period and impoundment period varied from 0.037~0.12 μmol·L⁻¹ and 0.11~0.23 μmol·L⁻¹, with the average values of (0.066 ± 0.0067) μmol·L⁻¹ and (0.13 ± 0.034) μmol·L⁻¹. The CH₄ flux was (0.941 ± 0.217) μmol·m⁻²·h⁻¹ in low-water-level period and (1.915 ± 0.204) μmol·m⁻²·h⁻¹ in impoundment period. CH₄ was produced by CO₂ reduction and acetic acid fermentation, accounting for 17.95% and 82.05% of the total CH₄ production, respectively. The dissolved CH₄ concentration was significantly positively correlated with DO and NO₃⁻-N, and it is opposite with dissolved inorganic carbon. The dissolved CH₄ concentration in this study area is affected by water environment (33.42%), inorganic nitrogen (29.60%), organic carbon (23.88%), and inorganic carbon (13.10%), and anthropogenic influences promoted dissolved CH₄ concentration.
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