Table 1.
Leaching of the unoxidized soil fraction without pH control [i.e. near neutral pH; number of replicates (n) = 3], the partially oxidized soil fraction without pH control (n = 3), and the partially oxidized soil fraction set at an initial pH of 3 including controls (n = 2–5). Data are presented as averages ± SD
| Inoculum | Days* | Fetot (mM) | Fesup (mM) | Fe2+sol (mM) | Redox (mV)† | Redox vs. SHE (mV)‡ | pH | |
|---|---|---|---|---|---|---|---|---|
| 1. Unoxidized§ | None | 0 | 22.4 ± 0.8 | 0.0 ± 0.0 | 3.9 ± 0.1 | 445 ± 1 | 650 ± 1 | 7.9 ± 0.1 |
| 45 | 30.7 ± 1.5 | 0.2 ± 0.0 | 4.6 ± 0.3 | 641 ± 3 | 846 ± 3 | 3.0 ± 0.4 | ||
| 2. Partially oxidized | None | 0 | 16.5 ± 0.4 | 0.4 ± 0.2 | 3.3 ± 0.3 | 399 ± 15 | 604 ± 15 | 4.2 ± 0.1 |
| 45 | 25.2 ± 2.4 | 0.0 ± 0.0 | 2.7 ± 0.3 | 590 ± 5 | 795 ± 5 | 3.5 ± 0.1 | ||
| 3. Partially oxidized | None (plus thymol) | 0 | 18.6 ± 4.4 | 0.2 ± 0.1 | NA¶ | 265 ± 10 | 470 ± 10 | 4.2 ± 0.1 |
| 8 | 23.9 ± 3.4 | 0.1 ± 0.1 | NA | 312 ± 4 | 517 ± 4 | 4.2 ± 0.1 | ||
| 4. Partially oxidized | None (no thymol) | 0 | 21.9 ± 1.9 | 0.1 ± 0.0 | 0.0 ± 0.0 | 174 ± 20 | 379 ± 20 | 4.2 ± 0.1 |
| 8 | 26.6 ± 3.5 | 0.5 ± 0.3 | 0.0 ± 0.0 | 461 ± 39 | 666 ± 39 | 3.0 ± 0.2 | ||
| 5. Partially oxidized | Enrichment | 0 | 27.1 ± 2.7 | 0.4 ± 0.0 | 2.2 ± 1.9 | 327 ± 4 | 532 ± 4 | 4.2 ± 0.1 |
| 8 | 39.1 ± 3.6 | 0.4 ± 0.0 | 1.2 ± 1.6 | 582 ± 6 | 787 ± 6 | 3.0 ± 0.1 |
*
Number of days leaching experiment was carried out.
†
Pt electrode against Ag0/AgCl reference with 3.5 M KCl.
‡
Redox potentials vs. the SHE were calculated from the measured redox potential values by the addition of 205 mV.
§
Numbers denote the experiment numbers listed in the methods and results.
¶
Data not available as thymol interferes with the ferrous iron assay.