TABLE 2.
Parameter | Result for location: |
|||
---|---|---|---|---|
Upstream |
Downstream |
|||
Terrace | Pool | Terrace | Pool | |
Avg mass of sediments (g) | 103 ± 9.30 | 13.0 ± 9.70 | 100 ± 3.20 | 11.8 ± 2.58 |
Avg surface area of sediments (cm2) | 130 ± 17.0 | 59.8 ± 11.2 | 119 ± 17.9 | 56.5 ± 17.5 |
Avg net Fe(II)out/Fe(II)in | 0.45 ± 0.04 | 0.61 ± 0.02 | 0.73 ± 0.02 | 0.80 ± 0.01 |
Avg net Feout/Fein | 0.73 ± 0.02 | 0.79 ± 0.09 | 0.86 ± 0.04 | 0.88 ± 0.02 |
RFe(II) (10−7 mol liter−1 s−1) | 1.58 ± 0.53 | 1.03 ± 0.31 | 0.75 ± 0.25 | 0.57 ± 0.23 |
RFe(II) (10−9 mol liter−1 s−1 g−1) | 1.60 ± 0.41 | 10.4 ± 6.58 | 0.74 ± 0.24 | 4.79 ± 1.58 |
RFe(II) (10−9 mol liter−1 s−1 cm−2) | 1.25 ± 0.49 | 1.75 ± 0.56 | 0.63 ± 0.17 | 1.08 ± 0.52 |
All results were calculated from dissolved Fe(II) and dissolved total Fe concentrations measured under pseudo-steady-state conditions achieved at a 10-h hydraulic residence time. Sediment mass and surface area values represent means ± standard deviations (SD) for four measurements (where n = 4 = duplicates from two reactor series = 4 sediment pieces). Rate (R) and extent values represent means ± SD calculated from multiple measurements made under the pseudo-steady-state conditions (3 to 5 sampling points) using duplicate reactor series (where n = 6 to 10 = 3 to 5 sampling points × 2 duplicate reactor series).