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.
Keywords: CH4 flux; Dissolved CH4 concentration; Generation pathways of CH4; Influence factors of CH4; Three Gorges Reservoir.
© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.