Table 2.
Changes (absolute [Δ] and percent [%]) in mean (and median) lake concentrations between the 1997 and 2007 lake surveys (n = 60). Statistical difference between surveys was assessed with the non-parametric Wilcoxon signed paired test
| Variable | Units | Δ Change | % Change | Wilcoxon§ |
|---|---|---|---|---|
| SO42− | μmolc l−1 | −7.6 (−12.0) | −9.3 (−14.8) | 0.001 |
| nmSO42− | μmolc l−1 | −10.5 (−8.1) | −57.6 (−46.2) | 0.000 |
| pH | −0.03 (0.08) | −0.60 (1.60) | 0.352 | |
| Cl− | μmolc l−1 | 28.6 (30.9) | 4.6 (5.4) | 0.025 |
| Conductivity | μS cm−1 | −1.1 (−0.6) | −1.1 (−0.7) | 0.763 |
| Alkalinity | μmolc l−1 | 5.0 (6.1) | 47.3 (62.5) | 0.003 |
| Ca2+ | μmolc l−1 | −3.7 (0.1) | −5.9 (0.2) | 0.007 |
| Mg2+ | μmolc l−1 | 0.3 (−7.5) | 0.2 (−5.6) | 0.903 |
| nmCa2+ | μmolc l−1 | −4.8 (−0.4) | −11.8 (−1.4) | 0.000 |
| nmMg2+ | μmolc l−1 | −5.3 (−7.8) | −22.9 (−35.9) | 0.004 |
| nmK+ | μmolc l−1 | −0.3 (0.0) | −10.6 (2.2) | 0.594 |
| DOC | mg l−1 | 0.7 (1.6) | 13.7 (47.9) | 0.054 |
| AlT | μmol l−1 | −0.03 (−0.002) | −1.2 (−0.1) | 0.683 |
§Changes in lake chemistry between surveys were assumed to be statistically significant at p < 0.05. Units: 1 mol of charge (molc) is equal to 1 equivalent (eq)