Thermochemolysis of genetically different soil humic acids and their fractions obtained by tandem size exclusion chromatography-polyacrylamide gel electrophoresis

摘要

Humic acids (HA) from soils of very different origin and bioclimatic conditions (podzoluvisol, phasozem, chernozem, and ferralsol) were fractionated by coupling size-exclusion chromatography and polyacrylamide gel electrophoresis (tandem SEC-PAGE). From each HA, three fractions-A, B, and C+D, with different molecular sizes and electrophoretic mobilities-were obtained and analysed by thermochemolysis, the products being identified subsequently by gas chromatography/mass spectrometry. Regardless of HA origin, fraction A contained considerably more n-fatty acids and n-alkanes derived from plant waxes than did fractions B and C+D. Lignins accumulated mainly in fractions B and C+D. These results show that tandem SEC-PAGE allowed the separation of soil HA into fractions enriched in different structural components whose distribution was independent of HA genesis.