As the biggest inter-basin water transfer scheme in the world,the South-to-North Water Diversion Project (SNWD) was designed to alleviate the water crisis in North China.The main channel of the middle route of the SNWD is of great concern in terms of the drink-ing water quality.In this study,we tested the hypothesis that the dissolved organic matter(DOM) derived from the planktonic algae causes the rising levels of CODMn along the mid-dle route by monitoring data on water quality (2015-2019,monthly resolution).The results showed that algal density in the main channel increased along the channel and was sig-nificantly correlated with CODMn (p ＜ 0.01).Five fluorescent components of DOM,includ-ing tyrosine-like (14.85％),tryptophan-like (22.48％),microbial byproduct-like (26.34％),ful-vic acid-like (11.41％),and humic acid-like (24.92％) components,were detected.The level of tyrosine-like components increased along the channel and was significantly correlated with algal density (p＜0.01),indicating that algae significantly changed the level of DOM in the channel.Algal decomposition and metabolism were found to be the main mechanisms that drive the changes in CODMn.Therefore,controlling algal density would be an impor-tant measure to prevent further increase in CODMn and for the guarantee of excellent water quality.

Chao Wang;Hong Zhang;Pei Lei;Xiaokang Xin;Aijing Zhang;Wei Yin

Changjiang Water Resources Protection Institute,Wuhan 430051,China;Key Laboratory of Ecological Regulation of Non-point Source Pollution in Lake and Reservoir Water Sources,Wuhan 430051,China;State Key Laboratory of Environmental Aquatic Chemistry,Research Center for Eco-Environmental Sciences,Chinese Academy of Sciences,Beijing 100085,China;State Key Laboratory of Pollution Control and Resources Reuse,School of the Environment,Nanjing University,Nanjing 210046,China;Construction and Administration Bureau of South-to-North Water Diversion Middle Route Project,Beijing 100038,China

环境科学学报（英文版）

[1]Chao Wang;Hong Zhang;Pei Lei;Xiaokang Xin;Aijing Zhang;Wei Yin-.Evidence on the causes of the rising levels of CODMn along the middle route of the South-to-North Diversion Project in China:The role of algal dissolved organic matter)[J].环境科学学报（英文版）,2022(03):281-290

SNWD

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