Parameters Minimum Maximum Average Standard deviation
pH 7.5 8.4 7.9 0.2
EC(° s/cm) 0.7 4010.0 2209.0 912.2
TDS(mg/L) 430.0 2955.0 1432.4 626.2
DO(mg/L) 0.0 6.8 1.61 1.36
DOC(mg/L) 0.0 11.2 4.3 2.2
Ca2+(mg/L) 28.0 123.0 59.3 19.8
Mg2+(mg/L) 15.0 119.0 73.2 30.3
Na+(mg/L) 107.0 460.0 293.5 90.8
K+(mg/L) 7.0 73.0 38.7 15.5
Total As(° g/L) 77.0 1469.1 450.4 314.3
Fe(mg/L) 0.1 5.1 0.8 1.1
NH4+(mg/L) 0.0 16.8 7.1 4.1
NO3-(mg/L) 0.0 2.8 0.5 0.6
NO2-(mg/L) 0.0 13.5 1.4 2.9
HCO3-(mg/L) 191.0 650.0 504.4 84.8
Cl-(mg/L) 19.0 802.0 391.9 215.6
SO42-(mg/L) 1.0 316.0 102.9 82.8
Table 1: Summary of aquitard groundwater quality in monitoring well YL7 during
1992-2005.