Table 2.
Examples of environmental and physiological factors that affect autotrophic carbon fractionation.
| Variable | Taxa | 13C/12C isotope discrimination change (↑ or ↓) with increase in variable | Reference |
|---|---|---|---|
| Temperature | Land plants (varied) | ↓ (≤ ~4‰) | [123] |
| Diatoms (varied) | ↓ (≤~7‰; less change at high [CO2]) | [124] | |
| Marine plankton (varied) | ↑ or ↓, dependent on taxa (≤ ~4‰) | [125] | |
| pH | Spinacea oleracea (land plant) | ↓ (≤ ~3‰) | [15] |
| Skeletonema costatum (diatom), Emiliania huxleyi (coccolithophore) | ↑ or ↓, dependent on pH range (≤ ~9‰) | [47] | |
| CO2 concentration | Land plants (varied) | ↑ (≤ ~7‰) | [126] |
| Skeletonema costatum (diatom), Emiliania huxleyi (coccolithophore) | ↑ (≤ ~7‰) | [47] | |
| Emiliania huxleyi (coccolithophore) | ↑ (≤ ~7‰) | [127] | |
| Emiliania huxleyi (coccolithophore) | ↑ (≤ ~7‰) | [128] | |
| Growth rate | Phaeodactylum tricornutum (diatom) | ↓ (≤ ~20‰) | [129] |
| Emiliania huxleyi (coccolithophore) | ↓ (≤ ~7‰) | [128] | |
| Marine plankton (field samples) | ↓ (≤ ~9‰) | [130] | |
| Marine plankton (field samples) | ↓ (≤ ~8‰) | [131] | |
| Cell surface area:volume | Marine plankton (varied) | ↑ (≤ ~20‰) | [132] |
| H2 concentration | Methanothermobacter marburgensis (methanogen) | ↓ (≤ ~30‰) | [133] |
| Methanocaldococcus jannaschii (methanogen) | ↓ (≤ ~16‰) | [134] | |
| Pressure | Methanopyrus kandleri (methanogen) | ↓ (≤ ~22‰) | [135] |