Extraction and Characterisation of Humin Fraction from Amazonian Anthropogenic Dark Earths Soils('Terra Preta de indios')

摘要

Humin,the humic fraction that is insoluble in water at all pH values,typically comprises more than 50% of soil organic matter(1).Because of the difficulties in isolation,humin compositions and properties have been less extensively studied than those of humic and fulvic acids(2).On the basis of the accepted definition,humin can include any humic-type substances that are not dissolved during exhaustive extractions with aqueous base.