Effects of reservoir construction on optical and molecular characteristics of dissolved organic matter in a typical P-contaminated river

• Published in: Chemosphere (Oxford) 2023-11, Vol.341, p.140037-140037, Article 140037
• Main Authors: Liu, Hongni, Du, Yao, Shi, Zhanyao, Deng, Yamin, Gan, Yiqun, Xie, Xianjun
• Format: Article
• Language: English
• Subjects: DOM; FT-ICR-MS; Phosphorus; Reservoir; River
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2023.140037

The source and composition characteristics of dissolved organic matter (DOM) are crucial to identify and evaluate the sources of pollution in the watershed. The construction of reservoirs changes the hydrological condition and pollutant fate of the river. However, the effects of reservoirs' construction on DOM in the watershed and the underlying mechanisms are still unclear. This study aims to examine and compare the characteristics of DOM in reservoirs and streams in the Huangbai River, a typical reservoir-affected and P-contaminated river within the Yangtze River catchment. The results showed that DOM in reservoirs was characterized by more contribution from autochthonous source, under the influence of reservoirs’ construction; while, DOM in rivers was mainly originated from terrestrial input. Reservoirs had more lipid-like and protein-like compounds, while rivers contained more oxy-aromatic-like compounds. The percentage of CHOP molecules in reservoirs was significantly higher than that in rivers. The underlying mechanism is that more suitable conditions were created for plankton to grow after constructing reservoirs, which converted inorganic orthophosphate into organic phosphorus, and over time, organic phosphorus was gradually enriched in reservoirs, which exacerbated the risk of eutrophication in the reservoir water body. This study can provide theoretical support for monitoring and evaluation of water quality in reservoir-affected rivers. [Display omitted] •Find differences on DOM characteristics in reservoirs and mainstream.•Elucidate the influence of reservoirs construction on DOM in a P-contaminated river.•DOM in reservoirs and rivers are more autochthonous and more allochthonous, respectively.•Reservoirs contained higher amounts of CHOP molecules than rivers.•Stable conditions convert more inorganic P into organic P in reservoirs.