Redox properties of compost-derived organic matter and their association with polarity and molecular weight

Xiao-Song He; Chao Yang; Shao-Hong You; Hui Zhang; Bei-Dou Xi; Min-Da Yu; Si-Jia Liu

doi:10.1016/j.scitotenv.2019.02.164

Redox properties of compost-derived organic matter and their association with polarity and molecular weight

Sci Total Environ. 2019 May 15:665:920-928. doi: 10.1016/j.scitotenv.2019.02.164. Epub 2019 Feb 14.

Authors

Xiao-Song He¹, Chao Yang¹, Shao-Hong You², Hui Zhang¹, Bei-Dou Xi³, Min-Da Yu¹, Si-Jia Liu²

Affiliations

¹ State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China; State Environmental Protection Key Laboratory of Simulation and Control of Groundwater Pollution, Beijing 100012, China.
² College of Environmental Science and Engineering, Guilin University of Technology, Guilin 541006, China.
³ State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China; State Environmental Protection Key Laboratory of Simulation and Control of Groundwater Pollution, Beijing 100012, China. Electronic address: xibd@craes.org.cn.

PMID: 30790763
DOI: 10.1016/j.scitotenv.2019.02.164

Abstract

Compost-derived dissolved organic matter (DOM), which has a wide distribution of molecular weight (MW) and polarity, has a potential application in the remediation of the contaminated soil due to its redox-active functional groups. Composting treatment can change the MW and polarity of the DOM through microbial transformation and degradation. However, the relationship between the redox properties of compost-derived DOM and its MW and polarity is still unclear. DOM was extracted from municipal solid wastes with different composting times in this study, and it was further fractionated into humic acids (HA), fulvic acids (FA) and hydrophilic (HyI) fractions based on its hydrophobicity and XAD-8 resin. Electron transfer capacities [including electron accepting capacities (EAC) and electron donating capacities (EDC)] of the HA, FA and HyI fractions and their associations with polarity and MW were studied. The results showed that the EAC of the HA, FA and HyI all increased after composting. The EDC of the HA and HyI exhibited an increasing trend as well, though that of the FA decreased remarkably after composting. The MW, polarity and redox-active functional groups of the HA, FA and HyI fractions were determined using high performance liquid chromatography and excitation-emission matrix fluorescence spectra coupled with parallel factor analysis. The result showed that the quinone-like groups were mainly detected in the medium MW and transphilic sub-fractions of the HA, FA and HyI, and were the main functional groups responsible for the EAC. The low MW sub-fractions, which consisted mainly of tyrosine-like matter, were the main functional components accounted for the EDC. The results advance our understanding of the influence of MW and polarity on the redox properties of organic substances, and facilitate to reveal the important redox-active functional groups when compost is utilized to remediate the contaminated soil.

Keywords: Composting; Dissolved organic matter (DOM); Electron transfer capacities (ETC); Molecular weight (MW); Polar properties.