Ultraviolet humic-like component contributes to riverine dissolved organic matter biodegradation  

作　　者：Maofei Ni Siyue Li 

机构地区：[1]College of Eco-Environmental Engineering,Guizhou Minzu University,Guiyang 550025,China [2]Research Center for Environmental Ecology and Engineering,School of Environmental Ecology and Biological Engineering,Wuhan Institute of Technology,Wuhan 430205,China [3]The karst environmental geological hazard prevention laboratory of Guizhou Minzu University,Guiyang 550025,China [4]Key Laboratory of Reservoir Aquatic Environment,Research Center for Ecohydrology,Chongqing Institute of Green and Intelligent Technology,Chinese Academy of Sciences,Chongqing 400714,China

出　　处：《Journal of Environmental Sciences》2023年第2期165-175,共11页环境科学学报（英文版）

基　　金：financially supported by the National Natural Science Foundation of China (Nos. 31670473 and 42107091)

摘　　要：Biological degradation of dissolved organic matter(DOM)regulates its structure and fate in river ecosystems.Previous views suggested that labile components were dominantly consumed by microbial metabolism.Here we provide new observations that a part of recalcitrant compounds largely contribute to riverine DOM biodegradation.The excitationemission matrix fluorescent spectroscopy combined with peak picking and parallel factor analysis are used to explore component variability during DOM incubation.Humic-like and tryptophan-like DOM are the primary components of riverine DOM,with proportion contributions of 39%–82% and 16%–61% for % of the maximumfluorescence intensity,respectively.After 56 days of aerobic incubation in the dark,large amounts of tyrosine-like DOM generation are observed.Elevated temperature enhances the decomposition of ultraviolet humiclike substance and further stimulates labile DOM bio-mineralization into carbon dioxide.Meanwhile,averaged proportions of amino acid compositions(peak B and T)markedly increase(p<0.05)as the humic-like compositions(peak A,M and C)decrease after DOM incubation,suggesting incomplete degradation of refractory DOM from high-molecular to low-molecular weight compounds.The findings support the new notion of the continuous DOM biodegradation in a mode as“steps by steps”,contributing to a new understanding of carbon cycling for the UN Sustainable Development Goal.

关 键 词：Dissolved organic matter(DOM) Sequential biodegradation Recalcitrant compounds Component and fate Fluorescence analysis 

分 类 号：X52[环境科学与工程—环境工程]