Molecular aggregation of humic substances

Soil Science
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Abstract

Humic substances (HS) form molecular aggregates in solution and on mineral surfaces. Elucidation of the mechanism of formation of these aggregates is important for an understanding of the interactions of HS in soils arid natural waters. The HS are formed mainly by enzymatic depolymerization and oxidation of plant biopolymers. These reactions transform the aromatic and lipid plant components into amphiphilic molecules, that is, molecules that consist of separate hydrophobic (nonpolar) and hydrophilic (polar) parts. The nonpolar parts of the molecules are composed of relatively unaltered segments of plant polymers and the polar parts of carboxylic acid groups. These amphiphiles form membrane-like aggregates on mineral surfaces and micelle-like aggregates in solution. The exterior surfaces of these aggregates are hydrophilic, and the interiors constitute separate hydrophobic liquid-like phases.
Publication type Article
Publication Subtype Journal Article
Title Molecular aggregation of humic substances
Series title Soil Science
DOI 10.1097/00010694-199911000-00004
Volume 164
Issue 11
Year Published 1999
Language English
Publisher Kluwer
Contributing office(s) Toxic Substances Hydrology Program
Description 11 p.
First page 803
Last page 813
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