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Table 3 Relative distribution of integrated peak areas of chemical shift regions in the CP/MAS 13 C NMR spectra of partially decomposed materials collected from 3 organic horizons at 3 topographic positions

From: Characterization of soil organic matter in perhumid natural cypress forest: comparison of humification in different particle-size fractions

Topographic position Horizon C functional group (%) A/ O-A ratioa Aromaticityb
   alkyl O- alkyl di- O-alkyl aromatic carboxyl   
Summit Oi 34.1 30.5 15.0 13.7 6.7 0.75 0.15
  Oe 33.7 30.5 13.5 16.4 5.9 0.77 0.17
  Oa 33.5 30.0 12.5 16.2 7.8 0.79 0.18
Footslope Oi 26.7 31.6 15.4 18.3 8.0 0.57 0.20
  Oe 28.2 30.9 14.9 18.2 7.8 0.61 0.20
  Oa 27.8 30.1 14.4 19.9 7.7 0.62 0.22
Lakeshore Oi 30.9 26.4 15.4 19.9 7.4 0.74 0.21
  Oe 31.0 26.1 14.6 20.4 7.8 0.76 0.22
  Oa 31.3 25.9 14.2 20.7 7.9 0.78 0.22
  1. aalkyl-C peak area (0–50 ppm)/( (O-alkyl-C + di-O-alkyl C) peak area (50–110 ppm) ).
  2. baromatic C peak area (110–165 ppm)/ ((alkyl-C + O-alkyl-C + di-O-alkyl C + aromatic C) peak area (0–165 ppm)).