Table 5.
Resolution of Zn source contribution.
| Labeling approach | Labeled Zn source | Zn sources | 67Zn:66Zn isotope ratioa | Isotope enrichmentb | Experimental precisionc | Significantly distinguishable isotope ratiosd |
|---|---|---|---|---|---|---|
| mole mole−1 | mole mole−1 | mole mole−1 | − | |||
| Indirect | Heitenried soil (acidic) | Compost | 0.1473 | 0.1579 | 0.0027 | 58 |
| Soil available Zn | 0.3052 | |||||
| Strickhof soil (alkaline) | Compost | 0.1473 | 0.0702 | 0.0027 | 26 | |
| Soil available Zn | 0.2175 | |||||
| Direct | Wheat straw compost | Compost | 1.5552 | 1.4089 | 0.0034 | 414 |
| Soil available Zn | 0.1463 |
a
Mean isotope ratios of n = 4 treatment (soil available Zn) or processing replicates (compost). Isotope ratios were determined with Q-ICPMS.
b
Calculated as: isotope enrichment = 67/66Znlabeled.source− 67/66Znunlabeled.source.
c
Average of 95% confidence interval of the experimental precision (2sd of n = 4 treatment replicates) of either sources or sinks.
d
Calculated as: n = isotope enrichment : experimental precision.