Pyrolysis characterisation of plant, humus and soil extracts from Australian catchments

• Published in: Journal of analytical and applied pyrolysis 2002-12, Vol.65 (2), p.269-285
• Main Authors: Page, D.W., van Leeuwen, J.A., Spark, K.M., Mulcahy, D.E.
• Format: Article
• Language: English
• Subjects: Australian catchments; Dissolved organic matter (DOM); Off-line thermochemolysis; Pyrolysis–gas chromatography/mass spectrometry
• ISSN: 0165-2370; 1873-250X
• DOI: 10.1016/S0165-2370(02)00005-0

Dissolved organic matter (DOM) from vegetation, humus layers and soils of four reservoir catchments in south-eastern Australian were characterised by flash pyrolysis and off-line thermochemolysis using tetramethylammonium hydroxide (TMAH). The aim of this work was to identify organic compounds which might act as tracers of terrestrially derived bio-macromolecules to the drinking water reservoirs. Organic matter in reservoirs is a key issue to the water industry due to it being a precursor of disinfection by-products, causing taste and odours and is a substrate for microbial growth in a distribution system. Of the pyrolysis products detected from all three sample types (vegetation, humus and soils) most were molecular tracers of polysaccharides and to a lesser extent lignin and protein. Several benzyl and methoxyphenol compounds were detected from these samples that might enable tracing of terrestrial organic input to reservoirs. Compounds detected from vegetation, humus and soil samples by thermochemolysis were predominantly methoxy benzene structures, indicative of lignin sources and tannin, though compounds indicative of polysaccharides, lipids and resins acids were also detected. Ratios of syringyl to courmaryl moieties were found to be highest from locations with native hardwoods and these ratios consistently decreased from vegetation to humus to soil samples.