TABLE 1.
Physicochemical parameters of the groundwater at site H4 with two wells and further downstream at site H5a
| Site and date | Mean conductivity (μS cm−1) ± SD | Mean pH ± SD | Mean oxygen saturation (%) ± SD | Mean dissolved CO2 concn (mmol liter−1) ± SD | Mean bicarbonate concn (mmol liter−1) ± SD | Mean TOC concn (μmol liter−1) ± SD | Mean NO3− concn (μmol liter−1) ± SD | Mean NH4+ concn (μmol liter−1) ± SD | Mean SO42− concn (mmol liter−1) ± SD |
|---|---|---|---|---|---|---|---|---|---|
| H4-3 | |||||||||
| 24-mo study period | 747 ± 27 | 7.2 ± 0.1 | 5.3 ± 9.9 | 0.46 ± 0.17 | 6.74 ± 0.63 | 94.9 ± 9.2 | 6.0 ± 6.8 | 7.8 ± 3.0 | 0.37 ± 0.1 |
| Nov 2010 | 645 | 7.3 | 1.0 | ND | ND | 112.4 | BD | 10.8 | 0.39 |
| Apr 2011 | 754 | 7.2 | 3.5 | 0.45 | 7.55 | 83.3 | BD | 5.5 | 0.41 |
| H4-1 | |||||||||
| 24-mo study period | 748 ± 50 | 7.3 ± 0.1 | 38.3 ± 15.0 | 0.39 ± 0.18 | 6.33 ± 0.79 | 74.1 ± 10.8 | 121.2 ± 51.7 | 9.0 ± 6.7 | 0.79 ± 0.32 |
| Nov 2010 | 656 | 7.4 | 39.6 | ND | ND | 68.3 | 142.6 | 11.4 | 0.76 |
| Apr 2011 | 776 | 7.3 | 62.8 | 0.39 | 5.81 | 81.6 | 160.0 | BD | 1.09 |
| H5-1 | |||||||||
| 24-mo study period | 1013 ± 72 | 7.1 ± 0.1 | 37.1 ± 9.1 | 0.44 ± 0.18 | 5.43 ± 0.56 | 79.1 ± 10.0 | 137.3 ± 22.2 | 4.6 ± 4.5 | 2.53 ± 0.34 |
| Nov 2010 | 842 | 7.2 | 40.7 | ND | ND | 87.4 | 186.8 | 2.9 | 2.09 |
| Apr 2011 | 1051 | 7.2 | 36.8 | 0.44 | 5.47 | 94.9 | 131.0 | BD | 2.64 |
a
Data are from site H4 with two wells (wells H4-3 [12-m depth] and H4-1 [48-m depth]) and further downstream at site H5 (well H5-1 [88-m depth]). Data are means ± standard deviations of results obtained during a 24-month study period. For each site, values are also given for the months when samples were taken for diversity analysis. Well H4-3 was in the upper cycloides bank aquifer, whereas wells H4-1 and H5-1 were located in the lower trochite limestone aquifer. Detection limits for NO3− and NH4+ were 1 μmol liter−1 and 0.5 μmol liter−1, respectively. ND, not determined; BD, below the limit of detection.