蘑菇渣和稻秸堆肥中DOM与Cu^(2+)的络合机制

The Binding Properties of Cu^(2+)onto Dissolved Organic Matter from Mushroom Residue and Rice Straw Compost

堆肥中溶解性有机质(DOM)对重金属具有显著的络合作用,影响其在环境中的迁移和转化。研究采用三维荧光-平行因子(EEM-PARAFAC)结合二维相关光谱(2DCOS)分析方法,系统解析蘑菇渣堆肥(MRC)及水稻秸秆堆肥(RSC)中DOM与Cu^(2+)的络合机制。EEM-PARAFAC结果表明,MRC-DOM和RSC-DOM主要由类腐殖酸(C1)、类富里酸(C2)和类蛋白质(C3)组成,各组分分别占MRC-DOM总荧光强度的43%、32%和25%,占RSC-DOM的39%、29%和32%。2种堆肥DOM与Cu^(2+)作用过程中,3类组分荧光强度均呈不断降低趋势,表明它们均与Cu^(2+)发生了显著的络合作用。2种堆肥中不同荧光组分(C1~C3)与Cu^(2+)的有效猝灭常数(lg K)在4.54~4.76之间,均表现为C3>C1>C2,表明类蛋白组分(C3)与Cu^(2+)结合能力最强,其次为类腐殖酸(C1),类富里酸(C2)最低。2DCOS结果显示,堆肥DOM中类蛋白荧光组分与Cu^(2+)结合能力最强,而类富里酸优先与Cu^(2+)发生反应。总体而言,MRC-DOM和RSC-DOM中类蛋白和类腐殖质组分是与Cu^(2+)发生络合作用的关键物质,且2类堆肥DOM具有类似的Cu^(2+)络合机制(包括活性位点、络合能力和反应顺序)。研究结果为进一步了解堆肥对土壤Cu^(2+)迁移和转化行为的影响提供了重要的理论基础。

Dissolved organic matter(DOM)within compost readily complexes with heavy metals,influencing their migration and transformation in the natural environment.In this study,three-dimensional fluorescence-parallel factor(EEM-PARAFAC)and two-dimensional correlation spectroscopy(2DCOS)protocol were used to comprehensively analyze the binding properties of Cu^(2+)onto DOM derived from mushroom residue compost(MRC)and rice straw compost(RSC).The EEM-PARAFAC results show that the two compost-derived DOM primarily comprised humic-like acid(C1),fulvic-like acid(C2)and protein-like substances(C3).These components accounted for 43%,32%and 25%of the total fluorescence for MRC-DOM,and 39%,29%and 32%for RSC-DOM,respectively.During the interaction between the compost-derived DOM and Cu^(2+),the fluorescence intensity of the three PARAFAC-derived components consistently decreased.The result indicate that both the MRC-DOM and RSC-DOM had significant complexing affinities with Cu^(2+).Moreover,the lg K of fluorescent components in MRC-and RSC-DOM was between 4.54 to 4.76,and followed the order of C3>C1>C2.The results suggest that the protein-like components exhibited a stronger binding ability to Cu^(2+)than humic-like acid and fulvic-like acid substances in both types of compost DOM.2DCOS further confirm that protein-like fluorescent components had the highest binding affinity to Cu^(2+),while fulvic-like components exhibited a preferential reaction with Cu^(2+).In total,protein-like and humic-like substances within MRC-and RSC-DOM emerged as pivotal components for complexing with Cu^(2+).Furthermore,both types of compost-derived DOM exhibited similar binding behaviors,including the active binding sites,capacity and preferential sequence.These findings provide an important theoretical basis for comprehending the impact of compost application on the migration and transformation behavior of soil-bound Cu^(2+).