A careful analysis of many soil-derived humic acid samples shows nearly homologous composition after allowing for mild oxidation and amination. Proposed synthetic trajectory and exhaustive degradation studies also suggest common structural components for many humic acid models. One interpretation of this vast collection of studies is that the primary structural units of humic acid are chemically identical and result from controlled biosynthesis. Working with that hypothesis, an empirical formula for soil-derived humic acid has been proposed. Structural variation in related humic acid can be accounted for by oxidative conditions of the soil, level, soil nitrogen content, and propagation mechanisms. This proposed structure has been tested by sophisticated molecular modelling protocols, and possible biosynthetic pathways have been devised. The combination of these new approaches, reviewed here, leads to an exciting awareness of the utility and ubiquity of humic acid.
© 2003-2010 by Lawrence T. Sein. All rights reserved.
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