Table 1.
Carbon and nitrogen isotopic compositions of the investigated organic grains with δ15Nair values < 0, together with 12C14N–/12C– ratios. Relative errors for 12C14N–/12C– are < 0.009 (based on counting statistics); for the δ15N-values, we estimate an additional uncertainty of ~ 15 ‰ due to unknown matrix effects for the OM. Isotopic ratios are given in per mil; reported errors are 1 sigma.
| Grain | δ13C (‰) | δ15N (‰) | 12C14N–/12C– | dia. (nm)* |
|---|---|---|---|---|
| MAR002_CN_04_E | 34 ± 20 | –144 ± 29 | 1.37 | 400 ± 40 |
| MAR002_CN_12_A | –44 ± 3 | –252 ± 4 | 1.19 | 2780 ± 40 |
| MAR002_CN_12_B | –32 ± 4 | –145 ± 6 | 1.12 | 1830 ± 40 |
| MAR002_chain_N_A3_1_B | –11 ± 24 | –195 ± 29 | 1.89 | 350 ± 40 |
| MAR002_chain_N_A3_3_C | 38 ± 24 | –220 ± 34 | 0.90 | 430 ± 40 |
| MAR002_chain_N_A3_5_B | 3 ± 14 | –160 ± 28 | 0.55 | 510 ± 40 |
| MAR002_chain_N_A3_6_F | 47 ± 22 | –138 ± 44 | 0.76 | 350 ± 40 |
| MAR002_chain_N_A3_7_C | 19 ± 20 | –233 ± 26 | 0.94 | 510 ± 40 |
| MAR002_CN_28_02_E | –18 ± 20 | 31 | 1.09 | 480 ± 40 |
| MAR002_CN_29_02_F | 11 ± 31 | –220 ± 44 | 1.26 | 310 ± 40 |
*All given diameters represent recalculated values, which were determined from respective areas of the (typically non-circular) organic grains by assuming a circular shape for means of comparison. Given errors are based on the assumption of an uncertainty of ± 1 pixel when determining the outline of the grain and represent the pixel size for the respective secondary ion image.