苔草溶解性有机质对土壤吸附Cu^(2+)影响研究

Study on the Effect of Dissolved Organic Matter of Carex tristachya on Soil Adsorption of Cu^(2+)

该文以苔草为研究对象,利用红外光谱、紫外吸收光谱、三维荧光光谱分析了苔草溶解性有机质(DOM)的光谱特性,通过等温吸附平衡试验和吸附动力学试验研究了苔草DOM对土壤吸附Cu^(2+)的影响,分析了苔草DOM与Cu^(2+)反应前后成分变化。研究表明,苔草DOM具有羟基、羧基、羰基、甲基等官能团,由富里酸、类富里酸、类腐殖酸和类色氨酸4种组分组成,以相对分子质量较大的胡敏酸为主。加入苔草DOM会降低土壤对Cu^(2+)的最大吸附量、吸附平衡速率以及吸附亲和力。苔草DOM中的紫外区类富里酸物质和类腐殖酸物质可以通过羧基、羟基等官能团与Cu^(2+)产生络合作用,反应过后苔草DOM不饱和共轭双键结构数量、腐殖化水平、芳香环上取代基中的羰基、羧基、羟基和酯类含量均显著下降。研究结果可为苔草DOM的组成和结构提供基础数据,同时为解决DOM对重金属活性影响争议提供科学依据。

Using Carex tristachya as the research object,the spectral characteristics of dissolved organic matter(DOM)in moss were analyzed using infrared spectroscopy,ultraviolet absorption spectroscopy,and three-dimensional fluorescence spectroscopy.The effect of DOM of Carex tristachya on soil adsorption of Cu^(2+)was studied through isothermal adsorption equilibrium experiments and adsorption kinetics experiments,and the changes in composition before and after the reaction between DOM of Carex tristachya and Cu^(2+)were analyzed.Research showed that the DOM of Carex tristachya had functional groups such as hydroxyl,carboxyl,carbonyl,and methyl,and was composed of four components:fulvic acid,fulvic acid like,humic acid like,and tryptophan like,with humic acid with relatively high molecular weight being the main component.Added DOM of Carex tristachya could reduce the maximum adsorption capacity,adsorption equilibrium rate,and adsorption affinity of Cu^(2+)in the soil.The ultraviolet region like fulvic acid and humic acid like substances in the DOM of Carex tristachya could form a complex with Cu^(2+)through functional groups such as carboxyl and hydroxyl groups.After the reaction,the number of unsaturated conjugated double bond structures,humification level,and the content of carbonyl,carboxyl,hydroxyl,and ester in the substituents on the aromatic ring of DOM of Carex tristachya significantly decreased.The research results provide basic data for the composition and structure of DOM of Carex tristachya,and provide scientific basis for resolving disputes over the impact of DOM on heavy metal activity.