Molecular geochemistry of soil organic matter by pyrolysis gas chromatography/mass spectrometry (GC/MS) technique: A review

Abstract

Soil organic matter (SOM) is arguably the most complex and least understood component of soils. To analyze SOM structure and reduce SOM large structural heterogeneity, different components of SOM need to be separated into entities that differ in terms of source, composition, and turnover. Pyrolysis-gas chromatography/mass spectrometry (Pyrolysis-GC/MS) is to present the most effectual approach in the study of the pedogenesis of SOM; this uses thermal degradation to cleave bonds in the organic macromolecules and enables a sensitive and rapid characterization of organic constituents. Pyrolysis-GC/MS also aids the molecular characterization of microbial and plant-derived biomass and generates valuable data on the degradation and conservation rates of organic debris. This review provides an overview of commonly measured soil organic chemical constituents identified by Pyrolysis-GC/MS, including (i) aliphatics, fatty acids and sterols, (ii) carbohydrates, (iii) lignin, (iv) aromatic compounds and polycyclic aromatic hydrocarbons (PAHs) and (v) N-containing compounds.\r\r\t \r\r\tKey words: Soil organic matter (SOM), pyrolysis-gas chromatography/mass spectrometry (GC/MS), molecular geochemistry, organic compounds.