TABLE 1.
Physical and chemical properties of hot subsurface aquifer liquids and gases from the Hishikari gold mine
| Property | AW-S | AW-D |
|---|---|---|
| Chemical | ||
| Na+ (mg liter−1) | 510 | 530 |
| K+ (mg liter−1) | 23 | 27 |
| Mg2+ (mg liter−1) | 16 | 18 |
| Ca2+ (mg liter−1) | 85 | 75 |
| Cl− (mg liter−1) | 270 | 350 |
| HCO3− (mM) | 15.3 | 16.9 |
| SiO2 (mM) | 1.6 | 1.8 |
| SO42− (μM) | 514 | 508 |
| S2−/HS− (μM) | 94 | 110 |
| NH4+ (μM) | 93.9 | 98.6 |
| NO3− (μM) | 27.3 | 25.5 |
| NO2− (μM) | <2.0 | <2.0 |
| Fe(III) (μM) | 79 | 69 |
| Fe(II) (μM) | 72.3 | 73 |
| As(V) (μM) | 10.7 | 9.2 |
| As(III) (μM) | <1.0 | <1.0 |
| Se(VI) (μM) | 12.5 | 11.7 |
| Se(IV) (μM) | <3.0 | <3.0 |
| PO43− (μM) | 5.4 | 5.1 |
| S2O32− (μM) | 12.8 | 14.4 |
| Gas phase | ||
| H2 (ppm) | 1,520 | 1,480 |
| CH4 (ppm) | 27,600 | 32,400 |
| CO2 (ppm) | 736,000 | 744,000 |
| H2S (ppm) | <10 | <10 |
| Physical property | ||
| Temperature (°C) | 70.4 | 72.6 |
| pH | 6.25 | 6.12 |
| Conductivity (Sm−1) | 0.16 | 0.2 |
| Dissolved oxygen (mg liter−1) | 0.15 | 0.14 |
| Salinity (%) | 0.1 | 0.1 |
| Total dissolved solids (g liter−1) | 1.1 | 1.3 |
| Oxidation-reduction potential (mV) | −104 | −115 |