title: Chemical and structural evolution of humic acids during organic waste composting.
abstract: The effects of the composting process on the chemical and structural properties of humic acids have been studied in seven different organic waste mixtures from different origin. Only slight changes in elemental composition have been found in the humic acids after the composting process pointing to a more aromatic structure with higher proportions of oxygen and nitrogen. Functional groups were the most sensitive to the changes caused by the composting process showing a marked increase in the total acidity and phenolic, carboxyl and carbonyl groups. Gel permeation chromatography showed a slight increase in the average molecular weight of the humic acids. Infrared spectroscopy did not show important differences in humic acid structure but a clear decrease in the intensity of the bands in the region 3000-2850 cm(-1) corresponding to the aliphatic fractions. As a general result, the composting process yields humic acids in which the elemental and functional composition are closer to that of the more humified soil humic acids.
authors.affiliation: Department of Soil and Water Conservation and Organic Waste Management, Centro de Edafología y Biología Aplicada del Segura, CSIC, PO Box 4195, E-30080 Murcia, Spain.
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Sánchez-Monedero
authors.forename: Juan
authors.initials: J
authors.lastname: Cegarra
authors.forename: Diego
authors.initials: D
authors.lastname: García
authors.forename: Asunción
authors.initials: A
authors.lastname: Roig
mesh_terms: D001673:Biodegradation, Environmental; D006812:Humic Substances / Q000032:analysis*; D008372:Manure; D008970:Molecular Weight; D012722:Sewage; D012987:Soil; D013055:Spectrophotometry, Infrared; D018505:Waste Management
chemical_list: D006812:Humic Substances; D008372:Manure; D012722:Sewage; D012987:Soil