Table 1.
Comparison between different methods of quantifying ferrihydrite, in aquifer sediment samples from Bangladesh and Dover. Results are reported in both Fe concentrations (mg kg−1) and fractions (% of total and extractable Fe).
| Sediments | Analytical technique | Conventional single-sample method | Method of standard-additions | ||
|---|---|---|---|---|---|
| Concentration | Fraction | Concentration | Fraction | ||
| Bangladesh | EXAFS-LCF | 12700 ± 1700 mg kg−1 | total: 64 ± 9% | 13200 ± 2000 mg kg−1 | total: 66 ± 10% |
| Hydroxylamine-HCl extraction | 7770 mg kg−1 |
total: 39% extractable: 58% |
6810 ± 1360 mg kg−1 |
total: 34 ± 7% extractable: 49 ± 10% |
|
| Dover | EXAFS-LCF | 8140 ± 1690 mg kg−1 | total: 41 ± 9% | 1020 ± 1000 mg kg−1 | total: 5 ± 5% |
| Hydroxylamine-HCl extraction | 1420 mg kg−1 |
total: 7% extractable: 18% |
– | – | |