KMS Chongqing Institute of Green and Intelligent Technology, CAS
| Riverine CO2 supersaturation and outgassing in a subtropical monsoonal mountainous area (Three Gorges Reservoir Region) of China | |
Li, Siyue1 ; Ni, Maofei1,2; Mao, Rong1; Bush, Richard T.3
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| 2018-03-01 | |
| 摘要 | Rivers are an important source of CO2 to the atmosphere, however, mountainous rivers and streams with high emission rates are not well studied particularly in China. We report the first detailed investigation on monsoonal mountainous rivers in the Three Gorges Reservoir (TGR) region, with a focus on the riverine CO2 partial pressure (pCO(2)), CO2 degassing and their potential controls. The pCO(2) levels ranged from 50 to 6019 mu atm with averages of 1573 (SD. +/- 1060) in dry Autumn and 1276 (SD. +/- 1166) mu atm in wet Summer seasons. 94% of samples were supersaturated with CO2 with respect to the atmospheric equilibrium (410 mu atm). Monsoonal precipitation controlled pCO(2) seasonality, with both the maximal and minimal levels occurring in the wet season, and showing the overall effects of dilution. Riverine pCO(2) could be predicted better in the dry season using pH, DO% and DTP, whereas pH and DOC were better predictors in the wet season. We conclude that in-situ respiration of allochthonous organic carbon, rather than photosynthesis, resulted in negative relationships between pCO(2) and DO and pH, and thus CO2 supersaturation. Photosynthetic primary production was effectively limited by rapid flow velocity and short residence time. The estimated water-to-air CO2 emission rate in the TGR rivers was 350 319 in the Autumn and lower, yet more variable at 326 439 mmol/m(2)/d in Summer. Our calculated CO2 areal fluxes were in the upper-level magnitude of published data, demonstrating the importance of mountainous rivers and streams as a global greenhouse gas source, and urgency for more detailed studies on CO2 degassing, to address a global data gap for these environments. (C) 2018 Elsevier B.V. All rights reserved. |
| 关键词 | Riverine carbon flux CO2 degassing Partial pressure of CO2 Dissolved inorganic carbon Mountainous streams and rivers Three Gorges Reservoir catchment |
| DOI | 10.1016/j.jhydrol.2018.01.057 |
| 发表期刊 | JOURNAL OF HYDROLOGY
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| ISSN | 0022-1694 |
| 卷号 | 558页码:460-469 |
| 收录类别 | SCI |
| WOS记录号 | WOS:000427338900037 |
| 语种 | 英语 |
