Multivariate statistical analysis suggests that the groundwater could be subdivided into eight compositionally distinctive groups. Although division was set out only on the basis of major ions, further analysis of the trace elements, NO3− and NH4+, showed significant dependence on the eight groups, thus proving appropriate division of them. The results are summarized in Table 2.
Main geochemical and hydrogeological characteristics of each cluster
| Cluster (sample size) . | Dominant sampling source . | Positive PC scores . | Average deptha (m) . | Aquifer material . | Dominant aquifers . | Average TDS1 (mg/l) . | Median groundwater type . | Characteristics parameters . |
|---|---|---|---|---|---|---|---|---|
| C1 (N = 218) | MW, WS, SP, PW | PC1 and PC2 | 4–100 | Sandstone, sand, dolomite, till | Q, D3gj, middle Devonian | 520–700 | Ca–Mg–HCO3 | – |
| C2 (N = 213) | MW, WS, PW | PC2; PC1 or PC3 | 4–90 | Sandstone, sand, dolomite | Q, D3gj, middle Devonian | 400–500 | Ca–Mg–HCO3 | Highest median Al values |
| C3 (N = 223) | PW, SP, DR | PC2 and PC3 or PC2 and PC1 | 2–7 | Till, sand, dolomite | Q, D3pl-slp | 570–750 | Ca–Mg–HCO3 | Highest median Cd, Mn, Ni, Pb, U, Zn, NO3− values |
| C4 (N = 115) | WS, MW | PC1 and PC3 | 65–170 | Sandstone | Middle and lower Devonian | 780–1,520 | Ca–Mg–Na–Cl–SO4 | Highest median B, Br, Rb, Sb, Se, V values |
| C5 (N = 98) | MW, WS, SP | PC3 | 15–100 | Sandstone, dolomite, gypsum | D3pl-slp, D3gj | 800–2,050 | Ca–Mg–SO4 | Highest median Cu, F, Li, Sr values |
| C6 (N = 242) | PW, SP, MW | None or PC3 | 3–15 | Sand, sandstone | Q, D3gj, D2br | 170–300 | Ca–Mg–HCO3 | Low median trace element, nitrogen compound, TDS values |
| C7 (N = 240) | SP, PW, WS | PC2 or PC2 and PC3 | 3–50 | Sand, sandstone, dolomite | Q, upper and middle Devonian | 410–490 | Ca–Mg–HCO3 | – |
| C8 (N = 93) | MW, WS | PC2 or PC2 and PC1 | 25–75 | Sandstone, dolomite | Upper and middle Devonian | 420–570 | Ca–Mg–HCO3 | Highest median As, Ba, Fetot, Si, NH4+ values (low SO42−, Cl−, NO3−) |
| Cluster (sample size) . | Dominant sampling source . | Positive PC scores . | Average deptha (m) . | Aquifer material . | Dominant aquifers . | Average TDS1 (mg/l) . | Median groundwater type . | Characteristics parameters . |
|---|---|---|---|---|---|---|---|---|
| C1 (N = 218) | MW, WS, SP, PW | PC1 and PC2 | 4–100 | Sandstone, sand, dolomite, till | Q, D3gj, middle Devonian | 520–700 | Ca–Mg–HCO3 | – |
| C2 (N = 213) | MW, WS, PW | PC2; PC1 or PC3 | 4–90 | Sandstone, sand, dolomite | Q, D3gj, middle Devonian | 400–500 | Ca–Mg–HCO3 | Highest median Al values |
| C3 (N = 223) | PW, SP, DR | PC2 and PC3 or PC2 and PC1 | 2–7 | Till, sand, dolomite | Q, D3pl-slp | 570–750 | Ca–Mg–HCO3 | Highest median Cd, Mn, Ni, Pb, U, Zn, NO3− values |
| C4 (N = 115) | WS, MW | PC1 and PC3 | 65–170 | Sandstone | Middle and lower Devonian | 780–1,520 | Ca–Mg–Na–Cl–SO4 | Highest median B, Br, Rb, Sb, Se, V values |
| C5 (N = 98) | MW, WS, SP | PC3 | 15–100 | Sandstone, dolomite, gypsum | D3pl-slp, D3gj | 800–2,050 | Ca–Mg–SO4 | Highest median Cu, F, Li, Sr values |
| C6 (N = 242) | PW, SP, MW | None or PC3 | 3–15 | Sand, sandstone | Q, D3gj, D2br | 170–300 | Ca–Mg–HCO3 | Low median trace element, nitrogen compound, TDS values |
| C7 (N = 240) | SP, PW, WS | PC2 or PC2 and PC3 | 3–50 | Sand, sandstone, dolomite | Q, upper and middle Devonian | 410–490 | Ca–Mg–HCO3 | – |
| C8 (N = 93) | MW, WS | PC2 or PC2 and PC1 | 25–75 | Sandstone, dolomite | Upper and middle Devonian | 420–570 | Ca–Mg–HCO3 | Highest median As, Ba, Fetot, Si, NH4+ values (low SO42−, Cl−, NO3−) |
aExpressed as 25th and 75th percentile.
MW, monitoring well; WS, water supply well; SP, spring; PW, project well (Levins & Gosk 2007); DR, drainage.