| Popis: |
Humic substances (HSs) plays an important role in the degradation of organic pollutants and the passivation of heavy metals in soil, and their environmental effects are closely related to their electron transfer capacity (ETC). However, the effect of ventilation quantity on ETC of compost-derived HA is unclear. In this study, HS was extracted from compost with different ventilation quantities (0.1, 0.2, and 0.3 L kg−1 dry matter (DM) min−1, denoted as VQ1, VQ2, and VQ3, respectively) and divided into humic acids (HAs) and fulvic acids (FAs). Their ETC and electron recycling rate (ERR) were measured by electrochemical method. The structure and composition of HS and its evolution in composting process were analyzed by excitation–emission matrix spectroscopy, Fourier transform infrared spectroscopy, and ultraviolet and visible spectrophotometry. The influence of HS composition characteristics on ETC and ERR was investigated by correlation analysis. Results showed that the increase in the ventilation quantity did not change the composition structure of HS, but it affected the formation of HS. With the composting process, the electron donating capacity (EDC), electron accepting capacity (EAC), ETC, and ERR of the three piles VQ1, VQ2, and VQ3 showed an increasing trend. By contrast, the pile VQ2 with ventilation quantity of 0.2 L kg−1 DM min−1 enhanced EAC, ETC, and ERR of HA and FA mainly because of the accelerating consumption of lignin, protein-like, and aliphatic substances and the generation of aromatic and fulvic-like substances. Such transformation improved the humification degree. Correlation analysis showed that EDC, ETC, and ERR were correlated with the generation of FA, and EAC was correlated with the generation of HA. |
