Skip to main content

Table 5 Relative intensities of CP/MAS 13C NMR spectra in different particle-size fractions in different sampling locations

From: 13C NMR spectroscopy characterization of particle-size fractionated soil organic carbon in subalpine forest and grassland ecosystems

Site Particle size % of C functional groups HIa ARb
(μm) Carboxyl Aromatic O-Alkyl Alkyl
Forest Coarse (>250) 6.71 13.72 45.52 34.04 0.92 14.71
Large (250–53) 7.31 14.55 44.77 33.37 0.93 15.70
Medium (53–20) 6.35 13.20 43.43 37.02 1.06 14.10
Small (20–2) 7.12 11.14 43.32 38.43 1.11 11.99
Fine (2–0.4) 8.91 7.73 40.75 42.62 1.25 8.48
Very fine (<0.4) 5.61 10.46 45.18 38.74 1.03 11.08
Transition Coarse (>250) 5.13 16.25 55.04 23.58 0.53 17.13
Large (250–53) 6.95 21.20 49.27 22.58 0.59 22.78
Medium (53–20) 6.90 19.19 47.75 26.16 0.71 20.61
Small (20–2) 7.57 22.77 36.88 32.79 1.22 24.63
Fine (2–0.4) 7.45 16.93 44.16 31.45 0.92 18.29
Very fine (<0.4) 7.48 14.90 44.50 33.11 0.95 16.11
Grassland Coarse (>250) 6.03 14.95 56.14 22.88 0.51 15.91
Large (250–53) 6.78 16.79 53.95 22.48 0.53 18.02
Medium (53–20) 7.54 18.49 51.01 22.96 0.58 20.00
Small (20–2) 7.66 15.25 51.12 25.96 0.65 16.52
Fine (2–0.4) 6.65 8.10 51.76 33.50 0.80 8.68
Very fine (<0.4) 6.66 7.50 50.22 35.62 0.87 8.03
  1. aHumification degree of sampling soils: alkyl-C peak area (0–50 ppm)/O-alkyl-C peak area (50–110 ppm)
  2. bAromaticity ratio: aromatic-C peak area (110–165 ppm)/total peak area (0–165 ppm)