Rainstorm events shift the molecular composition and export of dissolved organic matter in a large drinking water reservoir in China: High frequency buoys and field observations

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  • Yongqiang Zhou, CAS - Nanjing Institute of Geography and Limnology, University of Chinese Academy of Sciences
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  • Miao Liu, CAS - Nanjing Institute of Geography and Limnology, University of Chinese Academy of Sciences
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  • Lei Zhou, Taihu Laboratory for Lake Ecosystem Research, CAS - Nanjing Institute of Geography and Limnology, University of Chinese Academy of Sciences
  • ,
  • Kyoung Soon Jang, Korea Basic Science Institute
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  • Hai Xu, CAS - Nanjing Institute of Geography and Limnology, University of Chinese Academy of Sciences
  • ,
  • Kun Shi, CAS - Nanjing Institute of Geography and Limnology, University of Chinese Academy of Sciences
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  • Guangwei Zhu, CAS - Nanjing Institute of Geography and Limnology, University of Chinese Academy of Sciences
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  • Mingliang Liu, Institute of Environmental Protection Science
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  • Jianming Deng, Taihu Laboratory for Lake Ecosystem Research, CAS - Nanjing Institute of Geography and Limnology, University of Chinese Academy of Sciences
  • ,
  • Yunlin Zhang, CAS - Nanjing Institute of Geography and Limnology, University of Chinese Academy of Sciences
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  • Robert G.M. Spencer, Florida State University
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  • Dolly N. Kothawala, Uppsala University
  • ,
  • Erik Jeppesen
  • Fengchang Wu, Chinese Research Academy of Environmental Sciences

Rainstorm events can flush large amounts of terrestrial organic-rich material into lakes that are used for drinking water. To date, few studies have been carried out to investigate how rainstorm events change the molecular composition, bio-lability, and flux of upstream-imported dissolved organic matter (DOM), which can impact the odor and taste of drinking water as well as the efficiency of wastewater treatment. We undertook high-frequency buoy monitoring and point sample collection (n = 495), during high, moderate, and low inflow discharge, in Lake Qiandao, a key drinking water source for about 10 million people. Data from two online fluorescent DOM sensors deployed and field samples collected at the river site, Jiekou, and the lake site, Xiaojinshan, showed that rainstorm events increased the specific UV absorbance (SUVA254), humification index (HIX), humic-like components (C1-C2), and FT-ICR MS derived condensed aromatic and polyphenolic compounds (p < 0.001) and decreased the spectral slope of DOM (S275–295), spectral slope ratio (SR), biological index (BIX), and highly bio-degradable peptide-like and aliphatic substances (p < 0.001). Our results suggest that rainstorm events enhanced the export to the lake of colored, hydrophobic, and aromatic DOM. Upstream-derived dissolved organic carbon (DOC) concentrations decreased (p < 0.001), while DOC bio-availability (BDOC) increased only slightly (p < 0.05) during rainstorm events. The loss rate of DOC in Lake Qiandao is 0.82 × 104 t C yr−1, of which 0.30 × 104 t C yr−1 is highly bio-labile, and higher occurrences of both ≥ 25 mm d 1 and ≥ 50 mm d 1 rainfall events are anticipated by linear fittings for this region in the future. The application of in situ fluorescence sensors provides an early warning of DOC surge incidents caused by rainstorm events and may be useful in advising drinking water treatment plant managers of changes in raw water DOM quality and treatability.

Original languageEnglish
Article number116471
JournalWater Research
Volume187
ISSN0043-1354
DOIs
Publication statusE-pub ahead of print - 28 Sep 2020

    Research areas

  • Dissolved organic matter (DOM), Drinking water lake, Fluorescence, FT-ICR MS, Molecular composition, Rainstorms

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