KMS Chongqing Institute of Green and Intelligent Technology, CAS
| CO2oversaturation and degassing using chambers and a new gas transfer velocity model from the Three Gorges Reservoir surface | |
Li, Siyue
| |
| 2018 | |
| 摘要 | Reservoirs are considered as important carbon source of the atmosphere, whilst, regional and global reservoir CO2quantification is hampered by data limitation and bias in spatial and temporal sampling. By deploying chamber measurements and employing the newly developed model of gas transfer velocity, CO2partial pressure (pCO2) and evasion in the main stem of the Three Gorges Reservoir (TGR) were investigated. The pCO2ranged from 429 to 8668 μatm with an average of 2511.6 ± 1721.3 μatm, 6.1-fold higher than the ambient air pCO2(mean: 410 μatm). All the samples were net CO2sources via water-air interface, displaying pronounced spatial and monthly variability. The CO2areal flux averaged 212.5 ± 120.1 mmol/m2/d in June, 123.3 ± 78.5 mmol/m2/d in July in the lotic TGR main stream, much higher than its lentic system, i.e., 79.6 ± 41.3 mmol/m2/d in November, and 76.3 ± 88.1 mmol/m2/d in March. Much lower k levels in the lentic reservoir surface resulted in lower CO2evasion rates. Furthermore, dam impoundment considerably altered the riverine carbon cycle, as reflected by the changing magnitude of CO2efflux and environmental controls of dissolved CO2. Precipitation and concurrent soil CO2influx exhibited a central role in controlling riverine pCO2, and respiration of allochthonous organic carbon was a secondary factor in the TGR lotic system, whilst, both in-stream metabolism and terrestrial inputs played crucial roles in controlling aqueous CO2in the TGR lentic system. In comparison, we provided key findings of k model and more reliable CO2quantification with a consideration of water level shifts and a complete coverage of spatial sampling. Our higher CO2emission (1.47 (1.16–2.13) Tg CO2/y) than previous studies called more field measurements to assess the resulting changes in CO2flux owing to dam operation and changing environment, and their implications for regional carbon budgets should be warranted. © 2018 Elsevier B.V. |
| DOI | 10.1016/j.scitotenv.2018.05.345 |
| 发表期刊 | Science of the Total Environment
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| ISSN | 00489697 |
| 卷号 | 640-641页码:908-920 |
| 收录类别 | EI |
| 语种 | 英语 |
| EISSN | 18791026 |
