Amorphous and condensed organic matter domains: the effect of persulfate oxidation on the composition of soil/sediment organic matter.
The composition of amorphous and condensed soil/sediment organic matter (SOM) domains was investigated for one soil sample and four sediment samples. These samples were oxidized with persulfate to remove amorphous SOM, before and after which the composition of SOM was studied by thermogravimetric analysis, pyrolysis-GC/MS, and cross polarization magic angle spinning 13C-NMR. Comparison of the SOM composition before and after oxidation showed that condensed SOM was more thermostable and less polar than amorphous SOM. Condensed SOM was relatively low in O-alkyl C and carboxyl C and it was likely to contain only small amounts of labile organic components (carbohydrates, peptides, fatty acids). Apart from these general characteristics, the composition of the condensed and amorphous domains appeared to be highly dependent on the origin and nature of the SOM investigated. Condensed domains in relatively undecomposed SOM were enriched in aliphatic C, whereas condensed domains in relatively weathered SOM were enriched in aromatic C. Altogether, the compositional changes upon persulfate oxidation were similar to the compositional changes upon humification, which supports the idea that weathered SOM is more condensed than the original material.
Cuypers
Chiel
C
Environmental Technology Department, Wageningen University, The Netherlands.
Grotenhuis
Tim
T
Nierop
Klaas G J
KG
Franco
Elena Maneiro
EM
de Jager
Adrie
A
Rulkens
Wim
W
D002247:Carbon Isotopes / Q000737:chemistry; D008401:Gas Chromatography-Mass Spectrometry; D019015:Geologic Sediments / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D009930:Organic Chemicals / Q000032:analysis; D010084:Oxidation-Reduction; D012987:Soil
D002247:Carbon Isotopes; D009930:Organic Chemicals; D012987:Soil