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| Dissolved characteristics and water-air interface exchange fluxes of CO2 and CH4 in Wuliangsuhai |
| Received:April 23, 2025 |
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| KeyWord:CO2;CH4;partial pressure and exchange flux;eutrophication;Wuliangsuhai |
| Author Name | Affiliation | E-mail | | LEI Kun | Inner Mongolia University of Science & Technology, School of Environment and Energy, Baotou 014000, China | | | MAO Yuqi | Inner Mongolia University of Science & Technology, School of Environment and Energy, Baotou 014000, China | | | JIAO Kunling | Inner Mongolia University of Science & Technology, School of Environment and Energy, Baotou 014000, China | jiaokunling@imust.edu.cn | | LI Jiaojiao | Inner Mongolia University of Science & Technology, School of Environment and Energy, Baotou 014000, China | | | ZHU Mengtao | Inner Mongolia University of Science & Technology, School of Environment and Energy, Baotou 014000, China | |
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| Abstract: |
| This study takes Wuliangsuhai, a large shallow lake in the arid to semi-arid regions of China, as a case study to investigate the spatiotemporal variations and driving factors of CO2 and CH4 exchange fluxes at the water-air interface. During the summer and autumn of 2024, samples of gas, surface and bottom water were collected from four functional zones（lake inlets, reed areas, algal areas, and lake areas） of Wuliangsuhai. The partial pressures and exchange fluxes of CO2 and CH4 were quantified using static chamber（Pc and Pm） and headspace equilibrium（Fc and Fm） methods. Seasonal dynamics of CO2 fluxes showed a clear shift from a source（+8 654.14 mg·m-2·d-1 in summer to a sink（-5 913.31 mg·m-2·d-1） in autumn. Spatially, CO2 was sequestered in the lake inlet and summer algal areas, whereas all other functional zones consistently emitted CO2. CH4 exhibited emissions across different seasons, with fluxes ranging from +86.32- +4 359.44 mg·m-2·d-1. The lake inlets and reed areas were identified as hotspots, exhibiting significantly elevated CH4 release compared to other functional zones. The vertical CO2 transport was governed by the Pc gradient between surface and bottom water. Seasonal temperature, eutrophication and DOC mediated distinct CO2 pathways. In summer, CO2 produced in bottom waters migrated upward but was assimilated by surface phytoplankton, driving atmospheric CO2 uptake. In autumn, CO2 accumulated in bottom waters and then ascended to the surface, ultimately releasing into the atmosphere. |
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