Natural versus anthropogenic controls on the dissolved organic matter chemistry in lakes across China: Insights from optical and molecular level analyses. (1st August 2022)

• Record Type: Journal Article
• Authors: Shang, Yingxin; Wen, Zhidan; Song, Kaishan; Liu, Ge; Lai, Fengfa; Lyu, Lili; Li, Sijia; Tao, Hui; Hou, Junbin; Fang, Chong; He, Chen; Shi, Quan; He, Ding
• Is Part Of: Water research. Volume 221(2022)
• Publication Date: 2022-08-01
• Subjects: DOM -- FT-ICR MS -- lake -- carbon cycle; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2022.118779
• Languages: English
• ISSNs: 0043-1354

Abstract

Highlights: Optical properties and molecular diversity of DOM across Chinese lakes were analyzed. Diverse DOM sources for humic-rich and protein-rich lakes across large-scale regions were firstly revealed. Natural and anthropogenic factors affecting regional DOM chemistry were evaluated quantitatively. Linkages between DOM optical properties and aquatic carbon parameters in Chinese lakes were established. Abstract: Dissolved organic matter (DOM) plays an essential role in the global carbon biogeochemical cycle for aquatic ecosystems. The complexity of DOM compounds contributes to the accurate monitoring of its sources and compositions from large-scale patterns to microscopic molecular groups. Here, this study demonstrates the diverse sources and compositions for humic-rich lakes and protein-rich lakes for large-scale regions across China with the linkage to optical components and molecular high-resolution mass spectrometry properties. The total fluorescence intensity of colored DOM (CDOM) for humic-rich lake regions (0.176 Raman unit; R.U.) is significantly ( p <0.05) higher than that of the protein-rich lake region (0.084 R.U.). The combined percentages of CDOM absorption variance explained by the anthropogenic and climatic variables across the five lake regions of Northeastern lake region (NLR), Yungui Plateau lake region (YGR), Inner Mongolia-Xinjiang lake region (MXR), Eastern lake region (ELR), and Tibetan-Qinghai Plateau lake region (TQR) were 86.25%, 82.57%, 80.23%, 88.55%, and 87.72% respectively. The averaged relative intensity percentages of CHOS and CHONS formulas from humic-rich lakes (90.831‰, 10.561‰) were significantly higher than that from the protein-like lakes (47.484‰, 5.638‰), respectively. The more complex molecular composition with higher aromaticity occurred in the humic-rich lakes than in the protein-rich lakes. The increasing anthropogenic effects would significantly enhance the sources, transformation, and biodegradation of terrestrial DOM and link to the greenhouse gas emission and the carbon cycle in inland waters. Graphical abstract: Image, graphical abstract