Table 1.
Statistical summaries (mean, standard deviation [SD], 5th percentile, median, 95th percentile) of catchment characteristics and lake chemistry (2007) for the study catchments (n = 60; see Fig. 1)
| Variable | Units | Mean | SD | 5%-tile | Median | 95%-tile |
|---|---|---|---|---|---|---|
| Lake size | ha | 4.4 | 8.4 | 0.5 | 1.6 | 13.3 |
| Catchment size | ha | 63.7 | 262.5 | 2.1 | 11.0 | 153.5 |
| Elevation | m | 291.6 | 169.1 | 28.8 | 278.0 | 561.2 |
| pH | 5.1 | 0.6 | 4.3 | 5.1 | 6.2 | |
| Conductivity | μS cm−1 at 25°C | 99.5 | 42.6 | 41.0 | 90.4 | 180.6 |
| Alkalinity (Gran) | μmolc l−1 CaCO3 | −5.6 | 32.3 | −51.7 | −3.6 | 45.9 |
| Ca2+ | μmolc l−1 | 59.5 | 31.5 | 23.1 | 55.1 | 105.4 |
| Mg2+ | μmolc l−1 | 145.5 | 70.4 | 57.0 | 127.3 | 289.1 |
| K+ | μmolc l−1 | 14.2 | 8.1 | 5.2 | 12.2 | 31.6 |
| Na+ | μmolc l−1 | 621.6 | 325.7 | 223.8 | 546.5 | 1323.5 |
| SO42− | μmolc l−1 | 74.1 | 29.0 | 35.9 | 69.3 | 129.9 |
| Cl− | μmolc l−1 | 644.5 | 303.0 | 220.3 | 600.7 | 1227.0 |
| NO3− | μmolc l−1 | 4.6 | 4.0 | 0.7 | 2.8 | 12.5 |
| DOC | mg l−1 | 5.7 | 2.8 | 2.2 | 4.9 | 11.1 |
| AlT | μmol l−1 | 2.5 | 1.9 | 0.5 | 2.1 | 6.9 |
| ANC | μmolc l−1 | 120.0 | 108.1 | 7.4 | 85.2 | 352.5 |
| nmCa2+ | μmolc l−1 | 35.7 | 27.7 | 8.2 | 32.0 | 72.7 |
| nmMg2+ | μmolc l−1 | 17.9 | 17.4 | −0.4 | 13.7 | 59.8 |
| nmK+ | μmolc l−1 | 2.6 | 5.8 | −6.3 | 2.4 | 10.7 |
| nmSO42− | μmolc l−1 | 7.8 | 14.7 | −13.9 | 9.7 | 25.6 |
Nitrate (NO3−) was available for only ~50% of the study lakes, DOC dissolved organic carbon estimated from absorbance at 320 nm (DOC = 49.5 × ABS320 + 1.69), AlT total (labile and non-labile) aluminum, ANC charge balance acid neutralizing capacity, nm non-marine (negative concentrations of non-marine base cations and SO42− may result from short-term variations in deposition). Units: 1 mol of charge (molc) is equal to 1 equivalent (eq)