Table 1. Details of EXAFS fit parameters for Serratia-precipitated uranium biominerals; fitting details are proved in Supporting Information.
| Sample | Path | Co-ordination number | Atomic distance (Å) | Debye-Waller factor σ2 (Å2) | Energy shift ∆E0 from calculated Fermi level (eV) | Reduced χ2 | R “goodness of fit” factor | Confidence level of adding shell (α)^ |
|---|---|---|---|---|---|---|---|---|
| UP biomineral | O ax | 2 | 1.80 (1) | 0.003 (1) | 9.68 ± 1.69 | 4,600 | 0.038 | - |
| O eq | 4 | 2.30 (1) | 0.005 (1) | - | ||||
| P monodentate | 4 | 3.66 (5) | 0.014 (10) | 0.91 | ||||
| OP ms | 8 | 3.69 (8) | 0.018 (11) | 0.76 | ||||
| UP biomineral “no fumarate” control | O ax | 2 | 1.80 (1) | 0.004 (1) | 8.12 ± 1.28 | 12,900 | 0.030 | - |
| O eq | 4 | 2.30 (1) | 0.005 (1) | - | ||||
| P monodentate | 4 | 3.63 (4) | 0.011 (7) | 0.93 | ||||
| OP ms | 8 | 3.70 (7) | 0.017 (8) | 0.73 | ||||
| Microbial U(VI) aq reduction | O eq1 | 4 | 2.31 (2) | 0.009 (2) | 4.01 ± 0.71 | 110 | 0.017 | - |
| O eq2 | 4 | 2.44 (3) | 0.015 (6) | 0.91* | ||||
| P bidentate | 2 | 3.13 (2) | 0.015 (4) | 0.98 | ||||
| U | 4 | 3.85 (1) | 0.006 (1) | 1.00 | ||||
| Microbial U(VI) s reduction | O ax1 | 1.8 | 1.80 (1) | 0.005 (1) | 6.14 ± 1.93 | 1,750 | 0.031 | - |
| O eq1 | 4.4 | 2.28 (2) | 0.007 (1) | - | ||||
| C | 1.25 | 2.93 (4) | 0.003 (5) | 0.71 | ||||
| P monodentate | 3.5 | 3.65 (4) | 0.012 (4) | 0.92 |
Amplitude factor (S02) was fixed at 1.0 for each sample. Numbers in parentheses are the SD on the last decimal place(s).
^ f-test results, α > 0.68 statistically improves fit with 1 sigma confidence, α > 0.95 with 2 sigma confidence
* This value is for splitting the shell of 8 equatorial oxygen into 4 and 4