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Changes in Water Chemistry Associated with Rainstorm Events Increase Carbon Emissions from the Inflowing River Mouth of a Major Drinking Water Reservoir

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  • Yuyang Li, CAS - Nanjing Institute of Geography and Limnology, Nanchang University
  • ,
  • Yongqiang Zhou, CAS - Nanjing Institute of Geography and Limnology, University of Chinese Academy of Sciences
  • ,
  • Lei Zhou, State Key Laboratory of Soil and Sustainable Agriculture, CAS - Institute of Soil Sciences
  • ,
  • Yunlin Zhang, CAS - Nanjing Institute of Geography and Limnology, University of Chinese Academy of Sciences
  • ,
  • Hai Xu, CAS - Nanjing Institute of Geography and Limnology, University of Chinese Academy of Sciences
  • ,
  • Kyoung Soon Jang, Korea Basic Science Institute
  • ,
  • Dolly N. Kothawala, Uppsala University
  • ,
  • Robert G.M. Spencer, Florida State University
  • ,
  • Erik Jeppesen
  • Justin D. Brookes, University of Adelaide
  • ,
  • Thomas A. Davidson
  • Fengchang Wu, Chinese Research Academy of Environmental Sciences

Large reservoirs are hotspots for carbon emissions, and the continued input and decomposition of terrestrial dissolved organic matter (DOM) from upstream catchments is an important source of carbon emissions. Rainstorm events can cause a surge in DOM input; however, periodic sampling often fails to fully capture the impact of these discrete rainstorm events on carbon emissions. We conducted a set of frequent observations prior to and following a rainstorm event in a major reservoir Lake Qiandao (China; 580 km2) from June to July 2021 to investigate how rainstorms alter water chemistry and CO2 and CH4 emissions. We found that the mean CO2 efflux (FCO2) (13.2 ± 9.3 mmol m-2 d-1) and CH4 efflux (FCH4) (0.12 ± 0.02 mmol m-2 d-1) in the postrainstorm campaign were significantly higher than those in the prerainstorm campaign (-3.8 ± 3.0 and +0.06 ± 0.02 mmol m-2 d-1, respectively). FCO2 and FCH4 increased with increasing nitrogen and phosphorus levels, elevated DOM absorption (a350), specific UV absorbance SUVA254, and terrestrial humic-like fluorescence. Furthermore, FCO2 and FCH4 decreased with increasing chlorophyll-a (Chl-a), dissolved oxygen (DO), and pH. A five-day laboratory anoxic bioincubation experiment further revealed a depletion of terrestrial-DOM concurrent with increased CO2 and CH4 production. We conclude that rainstorms boost the emission of CO2 and CH4 fueled by the surge and decomposition of fresh terrestrially derived biolabile DOM in this and likely many other reservoir's major inflowing river mouths.

TidsskriftEnvironmental Science and Technology
Sider (fra-til)16494–16505
StatusUdgivet - nov. 2022

Bibliografisk note

Funding Information:
This work was supported by the National Natural Science Foundation of China (grants 41930760, 42207447, 41977322, and 42071118), the Youth Innovation Promotion Association, CAS (2021312), NIGLAS Foundation (E1SL002 and 2022SKL008), the Provincial Natural Science Foundation of Jiangsu (BK20220162 and BK20220041), and the Chinese Postdoctoral Science Foundation (BX2021325). E.J. was supported by the TÜBITAK program BIDEB2232 (project 118C250). The authors would like to thank Manxue Zhang, Xiaoqin Yu, Huimin Chen, Chaorong Liu, Lili Chen, and Ziyi Han for their help with laboratory measurements and Anne Mette Poulsen for the English editions.

Publisher Copyright:
© 2022 American Chemical Society.

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