Table 1 Distribution of nitrate concentration in US Geological Survey wells by aquifer type and categories of land use in Lancaster, Lebanon, and Chester Counties, from 1976-2006
Well Location | Nitrate mg/L (NO3-N) | |||||
|---|---|---|---|---|---|---|
Aquifer | N | Median | Mean | Std. Dev. | Minimum | Maximum |
Piedmont and Blue Ridge crystaline-rock | 1676 | 3.00 | 4.35 | 4.88 | < .002 | 52.00 |
Piedmont and Blue Ridge carbonate rock | 1093 | 6.03 | 7.88 | 7.43 | 0.020 | 95.50 |
Early mesozoic basin | 469 | 3.77 | 4.96 | 5.28 | < .002 | 45.00 |
Valley and ridge carbonate rock | 241 | 11.00 | 13.60 | 13.39 | < .002 | 90.00 |
Valley and ridge | 134 | 1.02 | 2.12 | 2.86 | 0.010 | 16.64 |
Land use 1992 | N | Median | Mean | Std. Dev. | Minimum | Maximum |
Pasture | 1756 | 5.00 | 6.89 | 7.37 | < .002 | 90.00 |
Deciduous forest | 674 | 2.15 | 3.60 | 4.46 | 0.003 | 45.00 |
Row crop | 399 | 6.91 | 9.24 | 10.79 | 0.020 | 95.50 |
Low intensity residential | 289 | 3.68 | 4.49 | 4.91 | 0.003 | 52.00 |
Mixed forest | 173 | 2.50 | 3.81 | 3.84 | < .002 | 20.80 |
Commercial or industrial | 130 | 4.94 | 5.76 | 4.66 | 0.020 | 22.10 |
Evergreen forest | 121 | 3.63 | 4.85 | 4.37 | 0.003 | 21.50 |
High intensity residential | 21 | 5.95 | 5.09 | 2.47 | 0.690 | 9.23 |
Water | 17 | 3.72 | 4.61 | 5.39 | 0.020 | 22.00 |
Quarry mine gravel pit | 15 | 0.80 | 2.02 | 3.69 | 0.150 | 15.00 |
Transitional | 11 | 1.78 | 2.34 | 1.81 | 0.190 | 6.13 |
Urban grasses | 4 | 5.39 | 4.86 | 2.68 | 1.420 | 7.26 |
Woody wetland | 3 | 2.48 | 6.22 | 8.45 | 0.280 | 15.90 |
Overall | 3613 | 4.12 | 6.03 | 7.1 | < .002 | 95.5 |