Table 1. Average chemical composition of the Medee Lake brines. All concentrations in mmol kg−1 unless otherwise stated. Reported geochemical values are mean ± 5% (n = 6) obtained during 2010–2012 years unless otherwise stated. Abbreviations used: GB, glycine betaine; MPR, methane production rates; n.d., not determined.
| Parameters | Brine L1 2,940 m | Brine L2 2,975 m | Brine L3 3,010 m | Brine L4 3,102 m |
|---|---|---|---|---|
| Density, kg dm−3 | 1.19 | 1.21 | 1.22 | 1.22 |
| Temperature, °C | 14.45 | 14.73 | 15.32 | 15.44 |
| Salinity | 304 | 314 | 325 | 345 |
| Na+ | 4,022 | 4,110 | 4,165 | 4,178 |
| Cl− | 4,684 | 4,833 | 4,830 | 5,259 |
| Mg2+ | 603 | 630 | 773 | 788 |
| K+ | 331 | 363 | 462 | 471 |
| Ca2+ | 2.4 | 2.6 | 3.0 | 2.8 |
| SO42− | 140.4 | 146 | 166.9 | 201 |
| HS− | 0.67 | 0.93 | 0.97 | 1.64 |
| Br− | 49.0 | 53.3 | 62.6 | 65.3 |
| H3BO3 | 1.9 | 2.0 | 2.2 | 2.3 |
| NH4+ | 2.31 | 2.27 | 2.45 | 2.35 |
| Li+ μmol L−1 | 149 | 160 | 166 | 163 |
| CH4 μmol L−1 | 18.0 ± 3.1 | 70.3 ± 2.3 | 24.1 ± 3.3 | 13.9 ± 1.4 |
| Acetate μmol L−1 | 132 ± 21 | 539 ± 42 | 508 ± 37 | n.d. |
| GB nmol L−1 | 170 ± 9 | n.d. | 44 ± 7 | 0* |
| MPR, μmol L−1day−1 | 2.1 ± 0.2 | 3.1 ± 0.4 | 1.5 ± 0.6 | 0.5 ± 0.4 |
*The values correspond to the glycine betaine concentration found in the sediments collected at the depth of 3,105 m.