填埋初期水溶性有机物结构受电子转移的影响

Effect of electron transfer on the structure of dissolved organic matter during initial landfill stage

采集填埋初期的生活垃圾并提取DOM,以希瓦氏菌MR-1和柠檬酸铁(FeCit)分别作为电子供体和电子受体,利用三维荧光光谱(EEM)结合平行因子分析(PARAFAC)对电子转移前后DOM结构变化进行解析,以期揭示DOM电子转移对其结构的影响.PARAFAC模型揭示DOM由4个荧光组分组成,组分1(类色氨酸)和组分3(类酪氨酸)为类蛋白物质且其是DOM荧光的主要贡献成分,组分2(类富里酸)和组分4(类胡敏酸)为类腐殖质物质.类蛋白物质的荧光增强效应源于结构上含氮的杂环结构被破坏,疏水性增强.类腐殖质物质得到电子后其结构上的部分羰基变为醇基,荧光强度增加,且其荧光增加幅度在填埋过程中呈降低的趋势.类蛋白物质具有供电子能力,但其失去电子后结构改变荧光完全被猝灭.类腐殖质物质同样是DOM具有供电子能力的功能性组分且其荧光猝灭幅度受控于其结构上羧基和酚基等供电子基团的含量.类蛋白物质失去电子后不能重新被微生物还原返回原态,类腐殖质物质部分基团具有循环氧化还原能力,DOM的电子穿梭能力源于类腐殖质物质且随填埋的进行不断增强.

In order to investigate the structural change of dissolved organic matter after electron transfer,dissolved organicmatter(DOM)were extracted fromlandfilled wastes at different depthsduring initial landfill stage,and shewanellaShewanella MR-1and citrate iron(FeCit)were used as electron donor and electronacceptor,respectively.Furtherover,fluorescence excitation-emission matrix(EEM)spectra combined with parallel factor(PARAFAC)analysis was used toanalyze the structure change of DOM.The results indicated that four fluorescent components,i.e.,two humic-likecomponents(C2and C4)and two protein-like components(C1and C3),were identified by the PARAFAC analysis,andprotein-like components was the major component.The nitrogen-containing heterocyclic structure was desassembledwhen protein-like components got electrons,and theirhydrophobicity and fluorescence intensities were increased duringthe process.Fluorescence intensities of humic-like components were increased as well when they obtained electrons,though their increased range became decrease during the landfill processs.The carbonyl group on humic-like componentswere turn into alcohol group when it obatained electrons.Fluorescence quenching phenomenon was observeredwhenDOM loss electrons.Protein-like components wereable to offerelectrons,and theirstructure changed after they losselectrons.Humic-like substances can offer electrons as well,and their fluorescence intensities decreased as well whenthey loss electrons.However,the decreased range was related to the content of carboxyl and phenolic groups on humic-like subtaneces.Humic-like components could bereoxided,However,protein-like components could not be reduced afterthey was oxided.The electron shuttle capacityof DOM were ascribed to humic-like components,which werepersistentlyincreasedduring the landfill process.