TABLE 1.
Atom percent excess of N measured in nitrogen fractions in sediment enriched with NH415NO3a
| Carbon treatment | Nitrogen fraction | Mean atom% excess (SEM) (n = 3) at:
|
||
|---|---|---|---|---|
| 6 h | 24 h | 48 h | ||
| Control | NO3− | 37.12 (0.12) | 36.92 (0.09) | 36.16 (0.20) |
| NH4+ | 0.43 (0.26) | 0.29 (0.02) | 0.33 (0.08) | |
| NO2− | 28.68 (0.98) | 31.47 (1.36) | 28.09 (2.74) | |
| N2O | 37.85 (0.31) | 36.92 (0.10) | 36.04 (0.38) | |
| N2 | 35.97 (9.02) | 37.30 (0.33) | 36.97 (0.33) | |
| Glycine | NO3− | 37.25 (0.02) | 37.16 (0.03) | 36.50 (0.04) |
| NH4+ | 0.22 (0.03) | 0.20 (0.08) | 0.32 (0.03) | |
| NO2− | 25.53 (0.88) | 23.54 (0.57) | 26.37 (3.16) | |
| N2O | 37.54 (0.17) | 37.09 (0.09) | 36.57 (0.16) | |
| N2 | 43.63 (5.51) | 36.63 (0.00) | 36.63 (0.00) | |
| Acetate | NO3− | 37.39 (0.09) | 37.48 (0.04) | 37.17 (0.11) |
| NH4+ | 0.07 (0.01) | 0.19 (0.03) | 0.12 (0.01) | |
| NO2− | 18.77 (1.63) | 24.95 (0.32) | 32.92 (0.29) | |
| N2O | 34.36 (0.54) | 36.55 (0.08) | 36.16 (0.08) | |
| N2 | 0 | 0 | 0 | |
| Formate | NO3− | 37.48 (0.04) | 37.75 (0.06) | 37.08 (0.06) |
| NH4+ | 0.07 (0.02) | 0.13 (0.01) | 0.10 (0.01) | |
| NO2− | 25.45 (3.16) | 31.58 (2.05) | 36.37 (0.10) | |
| N2O | 35.92 (0.23) | 36.75 (0.11) | 36.80 (0.03) | |
| N2 | 0 | 0 | 0 | |
| Glucose | NO3− | 37.30 (0.06) | 37.01 (0.04) | 32.31 (1.55) |
| NH4+ | 0.16 (0.01) | 0.67 (0.07) | 2.03 (0.08) | |
| NO2− | 36.02 (1.04) | 34.48 (0.32) | 36.16 (0.21) | |
| N2O | 37.43 (0.48) | 37.14 (0.09) | 36.81 (0.23) | |
| N2 | 30.30 (1.86) | 37.63 (0.00) | 37.63 (0.00) | |
a
15N was measured in nitrogen fractions during incubation of sediment enriched with NH415NO3 and supplemented with different sources of carbon at 1.0 g of C liter−1.