重新认识土壤有机质  

Revisit soil organic matter

作　　者：渠晨晨 任稳燕 李秀秀 蔡鹏[1] 陈雯莉[1] 黄巧云[1] Chenchen Qu;Wenyan Ren;Xiuxiu Li;Peng Cai;Wenli Chen;Qiaoyun Huang(State Key Laboratory of Agricultural Microbiology,Huazhong Agricultural University,Wuhan 430070,China)

机构地区：[1]华中农业大学农业微生物学国家重点实验室,武汉430070

出　　处：《科学通报》2022年第10期913-923,共11页Chinese Science Bulletin

基　　金：国家自然科学基金(41830756,42007014)资助。

摘　　要：以腐殖质为主要成分的土壤有机质占土壤固相组成的2%~8%,是土壤中养分元素的承载者、微生物活动的驱动者以及矿质转化的调节者,对于土壤功能的发挥起着关键作用.早在19世纪初,德国土壤学者D?bereiner[1]和Sprengel[2]就提出“humic acids”概念.有学者利用碱提取和酸沉淀的方法将土壤有机质分成富里酸、胡敏酸以及高度缩合、惰性的胡敏素等不同组分[3-4].The accurate and comprehensive understanding of the molecular composition, source, and stabilization mechanism of soil organic matter(SOM) is vital for soil management and the preservation of organic carbon. Currently, a series of key scientific issues concerning the formation and stabilization of SOM is highly contentious. This review summarized the advances in the sources and molecular structure of SOM, and presented a systematic analysis of the different views,conflicts, and problems concerning soil humic substances in the past decades. The traditional view of soil science believes that SOMs are mainly composed of humic substances which are macromolecular compounds and are derived from plant and animal residues through a series of mineralization and humification processes. Soil enzymes and minerals, including phenol oxidase, laccase, peroxidase, iron oxide, manganese oxide, promote the polymerization of organic molecules through additive nucleophilic reactions and free radical catalyzation.13 C-NMR and FT-ICR-MS analyses supported the existence of humic substances in soils based on the structure and the molecular composition of SOM.However, with the application of biomarker analysis, high-resolution mass spectrometry, spatial resolution spectroscopy,and other advanced techniques, there is an emergence of new perspectives on the source and the structure of SOM. HPLCSEC showed the average molecular weight of Aldrich humic acid was significantly smaller than previously thought and the aggregation of humic substances was affected by acetic acid, p H and ionic strength. These evidences suggest that humic substances are aggregates of small organic compounds with a molecular weight of hundreds to thousands of Daltons, rather than macromolecules of tens to hundreds of thousands of Daltons. Furthermore, in situ observation of soil particles by STXM revealed significant heterogeneity of SOM at 50 nm spatial resolution. In terms of the origin of SOM, model calculations and biomarker analysis have indicated that microbial

关 键 词：土壤固相 土壤有机质 胡敏素 养分元素 富里酸 微生物活动 胡敏酸 碱提取 

分 类 号：S153.621[农业科学—土壤学]