Comparisons of soil organic matter and its fractions by pyrolysis mass-spectrometry

Abstract

Pyrolysis mass-spectra from a sample of the Al -horizon of a soH from southem Spain showed predominant peaks related to furan derivatives similar to those observed from complex polysaccharides in which not only hexoses but aiso pentoses and deoxyhexoses were constituent units. SmaHer peaks. typical for protein materials and phenolic units, were also observed. On the other hand. typical peaks for the methoxyphenols oí lignins were very small and indicated only limited amounts oC undecomposed lignín residues in this soH sample. Peaks related to benzene or toIuene were also very small.Humic acid samples from this soil showed much more prominent signals related to protein materíals, benzene and phenolic derivatives and weaker polysaccharide-related signals than did the entire sample. Typicallignin related peaks were smaIl or insignificant. Spectra from the grey or brown humidic acid fractions were much like those of the parent humic acid. Brown humic acid, however, showed stronger signals for nitrogen and sulphur compounds, indicating a higher content of protein-like materials in this fraction. Preparations of humic acid hydroIyzed by 6 N HCI showed in their pyrolysis products a marked increase in phenols and methoxyphenols.In its pyrogram, humin resembled humic acid, but signals for complex polysaccharides were more evident. Lignin-like materials seem not to be higher in this fraction. Hymatomelanic acid showed prominent signals related to polysaccharides and lignin. Pyrograms from the soH polysaccharides showed the characteristic pattern of a complex polysaccharide with the presence of fragments from polymers of amino acids or amino sugars. Fulvic acid spectra showed obvious dissimilarities to those from humic acid in that signals for protein, as well as those related to phenols, were low. Depending upon the isolation method, the fulvic acid preparations showed differing signals related to polysaccharide or phenolic materials.

Chemical characterization of soil organic matter fractions by analytical pyrolysis-gas chromatography-mass spectrometry

“…The sample taken represented a depth of 0-10 cm and had a pH of 5.6 in water, a carbon content of 3.5% and a nitrogen content of 0.4%. The applied fractionation procedure for soil organic matter is described elsewhere [1]. For the reader's convenience we have included Fig.…”

“…A further fractionation of humic acid into hymatomelanic acid, an ethanol-soluble fraction, is sometimes per formed. In addition to humic substances, polysaccharides are quantitatively important compounds present in soil organic matter [1].…”

“…fungal melanins, lignins, polysaccharides) have been reported. This analytical approach is used as a fingerprinting technique and clearly shows similarities and differences be tween different fractions present in soils [1,[3][4][5].…”

Evaluation of the organic matter composition of raw and composted municipal wastes

“…Compounds such as furfural and acetic acid which have been considered to be carbohydrates (Saiz-JimEnez et al 1979), may indicate the presence of substances such as undegraded cellulose, hemicellulose, etc. and, therefore, organic matter with low development.…”

Protease extraction from soil by sodium pyrophosphate and chemical characterization of the extracts

“…Styrene and oxylene were obtained by the pyrolysis of proteins as well as from carbohydrates and from the aromatic fraction of humus, and they clearly increase during humification (Alcañiz et al, 1987a). Acetic acid, furfural, acetophenone and acetamide derive from the thermal degradation of carbo¬hydrates (Saiz-Jiménez et al, 1979;Irwin, 1982;Ceccanti et al, 1986;Alcañiz et al, 1987a). Guaiacol, ethylphenol and vynil-guaiacol are characteristic producís of the pyrolysis of lignins, which tend to decrease during humification (Bracewell et al, 1980b;Alcañiz et al, 1987a).…”