Soil organic matter (SOM) of an Antarctic peaty soil (US soil Survey, 1994: Pergelic Terric Cryohemist; FAO, 1989: Terri-Gelic Histosol) at Casey Station, Wilkes Land, was studied with special emphasis on soil formation processes under extreme climate conditions. An integrated approach of modern analytical methods including wet-chemical analyses, cross polarization magic angle spinning carbon-13 nuclear magnetic resonance spectroscopy (CPMAS 13C-NMR) and pyrolysis-field ionization mass spectrometry (Py-FIMS) was applied to characterize the SOM composition at different depths. Dead moss material is the fresh organic matter of soil formation in the Pergelic Terric Cryohemist. Aliphat-C units dominate in the SOM. Py-FIMS indicate that the alkyl compounds consist of lipids, fatty acids and sterols. A high amount of carboxyl groups probably derives from fatty acids and proteins and the aromatic structures mainly from aromatic amino acids. The aromatic structures identified by CPMAS 13C-NMR and by Py-FIMS demonstrate that lignin input is not necessary for the formation of aromatic humic structures. A visible humification observed in the field was not confirmed with the data of the classical wet chemical analysis, whereas CPMAS 13C-NMR and Py-FIMS did. According to the used method combination data suggest, that within the humification process carbohydrates are less mineralized than under temperate climate conditions. Alkyl carbon units are enriched due to a selective preservation. During the further humification the alkyl carbon units are probably incorporated into the complex humic matter. The chemical degradation of the organic matter is not as intensive as in soils of temperate climate regimes. The extremely cold climate conditions retard the transformation of fresh organic residues. Therefore in this Antarctic peaty soil, carbohydrates dominate in the composition of the SOM in the deeper horizons.
Lothar Beyer Institute of Plant Nutrition and Soil Science University of Kiel D-24098 Kiel Olshausenstrasse 40 GERMANY 49-431-880-3191 49-431-880-2940 FAX Email: lbeyer@oeko-boden.bodenkunde.uni-kiel.de