Severe flood modulates the sources and age of dissolved organic carbon in the Yangtze River Estuary

Zhao Liang Chen; Yuanbi Yi; Wenjing Fu; Wenzhao Liang; Penghui Li; Kai Wang; Lixin Zhang; Kejun Dong; Si-Liang Li; Sheng Xu; Ding He

doi:10.1016/j.envres.2024.119040

Severe flood modulates the sources and age of dissolved organic carbon in the Yangtze River Estuary

Environ Res. 2024 Jul 1;252(Pt 3):119040. doi: 10.1016/j.envres.2024.119040. Epub 2024 Apr 29.

Authors

Zhao Liang Chen¹, Yuanbi Yi², Wenjing Fu³, Wenzhao Liang¹, Penghui Li⁴, Kai Wang⁵, Lixin Zhang⁶, Kejun Dong⁶, Si-Liang Li⁶, Sheng Xu⁶, Ding He⁷

Affiliations

¹ Department of Ocean Science and Center for Ocean Research in Hong Kong and Macau, The Hong Kong University of Science and Technology, Clear Water Bay, New Territories, 999077, Hong Kong, China.
² Department of Ocean Science and Center for Ocean Research in Hong Kong and Macau, The Hong Kong University of Science and Technology, Clear Water Bay, New Territories, 999077, Hong Kong, China. Electronic address: yuanbiyi@ust.hk.
³ Frontiers Science Center for Deep Ocean Multispheres and Earth System, and Key Laboratory of Marine Chemistry Theory and Technology, Ocean University of China, Qingdao, 266100, China.
⁴ School of Marine Sciences, Sun Yat-Sen University, Zhuhai, 519082, China; Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, 519080, China.
⁵ Department of Ocean Science and Engineering, Southern University of Science and Technology, Shenzhen, 518055, China.
⁶ Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin, 300072, China.
⁷ Department of Ocean Science and Center for Ocean Research in Hong Kong and Macau, The Hong Kong University of Science and Technology, Clear Water Bay, New Territories, 999077, Hong Kong, China; State Key Laboratory of Marine Pollution, City University of Hong Kong, Tat Chee Avenue, Kowloon, 999077, Hong Kong, China. Electronic address: dinghe@ust.hk.

PMID: 38692424
DOI: 10.1016/j.envres.2024.119040

Abstract

Floods in global large rivers modulate the transport of dissolved organic carbon (DOC) and estuarine hydrological characteristics significantly. This study investigated the impact of a severe flood on the sources and age of DOC in the Yangtze River Estuary (YRE) in 2020. Comparing the flood period in 2020 to the non-flood period in 2017, we found that the flood enhanced the transport of young DOC to the East China Sea (ECS), resulting in significantly enriched Δ¹⁴C-DOC values. During the flood period, the proportion of modern terrestrial organic carbon (OC) was significantly higher compared to the non-flood period. Conversely, the proportion of pre-aged sediment OC was significantly lower during the flood period. The high turbidity associated with the flood facilitated rapid transformation and mineralization of sedimentary and fresh terrestrial OC, modifying the sources of DOC. The flux of modern terrestrial OC transported to the ECS during the flood period was 1.58 times higher than that of the non-flood period. These findings suggest that floods can modulate the sources and decrease the age of DOC, potentially leading to increased greenhouse gas emissions. Further research is needed to understand the long-term impacts of floods on DOC dynamics in global estuaries.

Keywords: Dissolved organic carbon; Flood; Radiocarbon; Stable carbon isotope; Yangtze River Estuary.

MeSH terms

Carbon* / analysis
China
Environmental Monitoring
Estuaries*
Floods*
Geologic Sediments / analysis
Geologic Sediments / chemistry
Rivers* / chemistry
Water Pollutants, Chemical / analysis

Substances

Carbon
Water Pollutants, Chemical