Table 4.
Relative abundances of the functional groups identified by 13C NMR of lateritic soil with 90 and 1,080 days.
| Main functional groups | Chemical shift (ppm) | Relative abundances of functional groups in soil (%) | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| CK (days) | PAL (days) | BAS (days) | CCH (days) | OF (days) | |||||||
| 90d | 1080d | 90d | 1080d | 90d | 1080d | 90d | 1080d | 90d | 1080d | ||
| Alkyl-C | 0–44 | 27.75(0.2) | 27.14(0.2) | 10.90(0.3) | 26.74(0.2) | 8.83(0.1) | 23.68(0.2) | 4.91(0.2) | 13.14(0.2) | 17.24(0.2) | 24.22(0.2) |
| N-alkyl/Methoxyl-C | 44–68 | / | / | 5.81(0.1) | 0.78(0.3) | 17.55(0.1) | 14.21(0.1) | / | 13.15(0.1) | 17.59(0.1) | 16.43(0.1) |
| O-alkyl-C | 68–94 | 45.64(0.2) | 42.17(0.1) | 58.40(0.2) | 45.29(0.1) | 49.34(0.1) | 38.81(0.2) | 45.65(0.2) | 49.79(0.2) | 41.82(0.1) | 33.16(0.1) |
| Anomertic-C | 94–113 | / | / | 10.47(0.1) | 3.20(0.4) | 7.90(0.1) | 2.54(0.1) | 18.90(0.2) | 7.98(0.2) | 6.01(0.1) | 2.45(0.3) |
| Aromatic-C | 113–162 | 15.11(0.4) | 13.62(0.2) | 9.88(0.2) | 8.04(0.2) | 6.91(0.2) | 7.82(0.2) | 16.90(0.2) | 7.69(0.2) | 9.97(0.2) | 12.20(0.2) |
| Carbonyl-C | 162–220 | 11.50(0.5) | 16.43(0.6) | 4.54(0.3) | 12.75(0.1) | 9.48(0.1) | 12.92(0.1) | 3.14(0.2) | 8.34(0.2) | 7.3(0.8) | 11.53(0.6) |
| A/OA | / | 0.79 | 0.79 | 0.19 | 0.59 | 0.18 | 0.61 | 0.11 | 0.26 | 0.41 | 0.73 |
| AL/AR | / | 4.16 | 4.52 | 7.01 | 8.96 | 8.42 | 7.99 | 2.99 | 8.18 | 5.92 | 4.70 |
Values in parentheses are the noise level in the chemical shift region beyond 0–220 ppm. Chemical shift (ppm) refer to Han et al. (2020).