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Terrigenous organic carbon drives methane dynamics in cascade reservoirs in the upper Yangtze China
Zhang, Yuanyuan1,2; Su, Youheng2,3; Li, Zhe1,2; Guo, Shuhui4; Lu, Lunhui1,2; Zhang, Bin2; Qin, Yu3
2022-07-01
摘要Methane (CH4) emissions from freshwaters to the atmosphere have a profound impact on global atmospheric greenhouse gas (GHG) concentrations. Anthropogenic footprints such as dam construction and reservoir operation significantly changed the fate and transport of CH4 in freshwaters. The source of particulate organic carbon (POC) in reservoirs is a critical factor controlling CH4 production and emissions. However, little is known of how reservoir operation mediates the transport of POC and regulates CH4 accumulation in cascade hydroelectric reservoirs. Here, spatial and temporal variations in POC and CH4 were explored in the Xiluodu (XLD) and Xiangjiaba (XJB) reservoirs which are deep valley cascade reservoirs located in the main channel of the upper Yangtze River. Based on the delta 13C-POC and N/C mole ratio of particulate organic matter, the results of multiendmember stable isotope mixing models by a Bayesian model showed that terrigenous POC and autochthonous POC accounted for approximately 55% +/- 18% and 43% +/- 19% (SD, n = 179) of POC, respectively. Together with other hydrological and environmental parameters, we found that the input of terrigenous POC was dominantly influenced by water level variations and flow regulation due to reservoir operation. The cumulative effect of POC caused by cascade dams was not apparent. Terrigenous POC were more likely to drive CH4 accumulation in our study. Evident low level of CH4 in both reservoirs were likely affected by low sedimentation of POC and microbial CH4 oxidation. We hope our study could provide a conceptual framework for further modeling of CH4 dynamics in cascade reservoirs.
关键词Methane dynamics Terrigenous POC Carbon footprint Cascade reservoirs Hydropower production
DOI10.1016/j.watres.2022.118546
发表期刊WATER RESEARCH
ISSN0043-1354
卷号219页码:12
通讯作者Li, Zhe(lizhe@cigit.ac.cn)
收录类别SCI
WOS记录号WOS:000803703800005
语种英语