堆肥过程不同分子量水溶性有机物电子转移能力的演变及影响因素

利用超滤技术、电化学方法和光谱技术, 以堆肥水溶性有机物的不同分子量(MW)组分为研究对象, 分析在堆肥过程中不同分子量水溶性有机物(DOM)的组成特征、结构演变和电子转移能力变化的影响因素.结果表明, 类蛋白物质主要存在于堆肥前期的DOM(MW<1 kDa)中, 随着堆肥的进行, 类蛋白物质不断降解, 类富里酸物质持续合成, 堆肥后期类蛋白物质被完全降解, 类富里酸物质成为DOM(MW<1 kDa)主要的荧光组分.类腐殖物质是DOM(MW=1～3 kDa)、DOM(MW=3～5 kDa)和DOM(MW>5 kDa)的主要荧光组分, 堆肥过程中类腐殖质物质在3种不同分子量组分的变化各不相同, 但是堆肥后期类腐殖质物质在3个不同分子量组分的含量均高于堆肥初期. 堆肥过程中DOM(MW<1 kDa)的电子供给能力(EDC)呈降低趋势, 而电子接受能力(EAC)呈升高趋势; DOM(MW>5 kDa)的EDC在堆肥过程中呈上升趋势, 而EAC则无明显的变化规律.DOM(MW=1～3 kDa)和DOM(MW=3～5 kDa)的EDC和EAC在整个堆肥过程无明显变化规律.不同分子量组分堆肥DOM 的EAC受控于堆肥过程木质素降解产物的含量, 而其EDC变化与荧光参数和紫外参数无明显关系.

Effect of Compositional and Structural Evolution of Size-fractionated Dissolved Organic Matter on Electron Transfer Capacity during Composting

Ultrafiltration technology and spectrum technology were used to study the compositional and structural evolution of size-fractionated dissolved organic matter (DOM) during chicken manure composting. Electrochemical method was used to measure electron transfer capacity. The results showed that most of protein-like components were exist in DOM (MW<1 kDa) and it was the main components in DOM (MW<1 kDa) during initial composting. The protein-like components were persistently degraded and the humic-like components were persistently generated during composting process. The protein-like components didn′t exist in DOM (MW<1 kDa) and the fulvic-like components were the main components in the end of composting process. The humic-like substances were the main fluoresence components of DOM (MW=1-3 kDa, MW=3-5 kDa, MW>5 kDa). Though the changes of humic-like components with different molecular weight of DOM were different during composting, the content of humic-like components in the end of composting process was higher than that in the initial composting process. The electron donating capacity was persistently reducing and electron accepting capacity was persistently increasing for DOM with MW<1 kDa in the process of composting. In contrast, for the DOM with MW>1 kDa, the electron donating capacity was persistently increasing and the electron accepting capacity was irregular in the process of composting process. Meanwhile, the change of electron transfer capacity was irregular for DOM with MW = 1-3 kDa and MW=3-5 kDa. In a word, EAC of compost-derived DOM with size-fractionation was controlled by the aromatic carbon content which was derived from lignin degradation, but not related to spectrum parameter.