Characterizing soil organic matter in Arctic tundra soils by different analytical approaches

Soil organic matter (SOM) of five soil horizons from Arctic tundra and one soil horizon from a temperate region was separated into an extractable fraction (EF) and a non-extractable fraction (NEF) by dilute alkali. The modified classical fractionation method was applied to characterize SOM in the EF; and the wet chemical fractionation scheme, cross-polarization magic angle spinning (CP-MAS) C-13 NMR, and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) techniques were used to characterize SOM in the NEF. Each of these methods provides information on the chemical composition of SOM at varying angles. The NEF comprises a large amount of SOM in these arctic tundra soils and has great potential to influence carbon cycling in these ecosystems with climate warming. (C) 2002 Elsevier Science Ltd. All rights reserved.