Table 1.
Pore water chemistry for each of the boreholes at the time of sampling.
| Date | July 2008 | April 2009 | October 2009 | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Hole number | 1 | 2 | 3 | 1 | 2 | 3 | 1 | 2 | 3 |
| Pore water parameters measured in situ | |||||||||
| Dissolved oxygen (mg/L) | 0.0 | 0.0 | 0.0 | 1.5 | 1.1 | 0.7 | 1.2 | 1.3 | 1.3 |
| pH | 5.6 | 5.6 | 6.9 | 6.9 | 6.9 | 7.0 | 6.7 | 6.2 | 7.5 |
| Oxidation/reduction potential (mV) | −133 | −112 | −238 | na | na | na | −118 | −244 | −130 |
| Temperature (°C) | 17.6 | 15.9 | 19.4 | 7.6 | 6.5 | 7.1 | 11.2 | 11.5 | 11.2 |
| Dissolved metals (mg/l) | |||||||||
| As | 0.19 | 0.06 | 0.03 | 0.94a | 0.94 | 0.94 | 0.14 | 0.21 | 0.51 |
| Cd | 0.06 | 0.02 | 0.01 | 0.002 | 0.002 | 0.002 | 0.0006 | 0.0012 | 0.055 |
| Mn | 78 | 110 | 3.9 | 7.6 | 7.6 | 7.6 | 1.5 | 22 | 5.7 |
| Fe | 740 | 910 | 50 | 7.6 | 7.6 | 7.6 | 1 | 4.25 | 0.3 |
| Sb | 0.01 | 0.01 | 0.01 | 0.014 | 0.014 | 0.014 | 0.0028 | 0.002 | 0.0011 |
| Zn | 6.1 | 1.3 | 0.52 | 0.058 | 0.058 | 0.058 | 0.045 | 0.093 | 0.28 |
| Nutrients measured with chemets and hach kits (mg/l) | |||||||||
| Sulfide | 1.1 | 2.6 | 3.45 | 0 | 0 | 0 | 0 | 0 | 0 |
| Total phosphorous | 21 | 20 | 30 | 0.5 | 0.5 | 0.5 | 24 | 14 | 6.3 |
| Sulfate | 200 | 80 | 150 | 470 | 470 | 470 | 600 | 150 | 270 |
| Nitrite/nitrate | na/5.2 | na | na | 0.015/1.3 | 0.015/1.3 | 0.015/1.3 | 0.023/5.5 | 0.109/5.5 | 0.01/1.5 |
| Ammonium-N | 460 | 340 | 490 | 61 | 61 | 61 | 60 | 76 | 36 |
| Core solids chemistry | |||||||||
| Total C (%) | 9.39 | 10.65 | 6.23 | NSS | 10.6 | 18.3 | 18.3 | 7.12 | 3.32 |
| Total S (%) | 0.24 | 0.19 | 0.11 | NSS | 0.31 | 0.27 | 0.27 | 0.15 | 0.09 |
| As (ppm) | 2.7 | 2.9 | 1.8 | >250 | 16.6 | 18.9 | 45.8 | 9.3 | 18.9 |
| Cd (ppm) | 1.7 | 2 | 1.6 | 59.4 | 2.8 | 2.8 | 4.7 | 1.1 | 3.7 |
| Zn (ppm) | 108 | 122 | 18.6 | 1735 | 180 | 177 | 705 | 127 | 380 |
| Loss on ignition (%; 1,000°C) | 25 | 29.5 | 118 | NSS | 24.8 | 30.1 | 38.7 | 23.1 | 8.49 |
na, not available; NSS, not enough sample for the analysis.
When attempting to measure the ORP in April, two ORP probes were used. The ORP value continued to drop without stabilizing even after over an hour of being immersed in the pore water or lysimeter water.
aThere was insufficient water for chemical analysis from the bore holes, therefore water from the central lysimeter, which was located in close proximity to the boreholes, at the same depth as the bore holes was analyzed instead.