堆肥腐熟前后胡敏酸与富里酸的还原容量比较

采集腐熟前后的堆肥样品并提取和纯化出腐殖质(胡敏酸:HA;富里酸:FA),分别以柠檬酸铁(FeCit)和Fe(NO3)3作电子受体,测定了HA和FA的还原容量(RC).结果表明:以FeCit作为电子受体时,与未腐熟堆肥样品相比,腐熟后筛分样品HA的RC值增大,从22.85mmol e-/molC增大到26.84mmol e-/molC,而其对应FA的RC值减少,由37.67mmol e-/molC降低为33.68mmol e-/molC;对于两种不同形态的电子受体,以 FeCit为电子受体测定得到的RC值高于以Fe(NO3)3为电子受体测定得到的RC值;相对于本底还原容量,HA和FA经微生物还原后其RC值降低,降低幅度与微生物种类有关.结合紫外-可见光谱和三维荧光光谱分析发现,堆肥HA和FA的还原能力与其中类富里酸物质含量和醌基浓度成正相关,而与其本身的芳化度和分子量呈负相关.

The comparison of reduction capacity between humic acid and fulvic acid extracted from the compost

Humic substances, i.e., humic acids (HA) and fulvic acids (FA), were extracted from the uncomposted and composted samples, and used as the electron donators and mediators. The results showed that the RC of HA increased from 22.85mmol e-/molC to 26.84mmol e-/molC, whereas the RC of FA decreased from 37.67mmol e-/molC to 33.68mmol e-/molC after composting. The RC of HA and FA determined by FeCit was higher than that measured by Fe(NO3)3. Compared with the native RC, the microbial RC of humic substances decreased, and the decrease level was related to microbial species. Based on the composition analysis by UV-visible spectra and excitation-emission matrix spectra, it can be found that the RC is positively correlated with the content of humic-like substances and quinine, but it showed a negative correlation with the aromatic degree and molecular weight of humic substances.