Research Article
A Regional Scale Investigation on Groundwater Arsenic in Different Types of Aquifers in the Pearl River Delta, China
Table 1
Descriptive statistics of groundwater parameters in different types of aquifers.
| | Item | Total () | Granular aquifer () | Fissured aquifer () | Karst aquifer () | | Min | Max | Mean | SD | Min | Max | Mean | SD | Min | Max | Mean | SD | Min | Max | Mean | SD |
| | pH | 3.7 | 7.7 | 6.1 | 0.8 | 3.8 | 7.7 | 6.2 | 0.7 | 3.7 | 7.7 | 5.8 | 0.7 | 4.5 | 7.0 | 6.0 | 0.7 | | EC (μS/cm) | 22.0 | 6510.0 | 464.7 | 489.8 | 30.0 | 6510.0 | 562.0 | 542.0 | 22.0 | 2600.0 | 289.2 | 314.8 | 78.0 | 918.0 | 285.5 | 246.1 | | DO (mg/L) | 0.6 | 8.2 | 3.5 | 1.4 | 0.6 | 8.2 | 3.3 | 1.4 | 0.8 | 7.8 | 3.9 | 1.4 | 1.7 | 6.0 | 3.7 | 1.4 | | Eh (mV) | −200.0 | 330.0 | 75.8 | 83.4 | −34.0 | 298.0 | 66.9 | 79.7 | −200.0 | 330.0 | 89.0 | 86.8 | −7.0 | 262.0 | 126.3 | 97.2 | | TDS (mg/L) | 17.1 | 3733.9 | 368.2 | 396.3 | 29.5 | 3733.9 | 457.7 | 454.2 | 17.1 | 864.4 | 207.1 | 168.7 | 60.0 | 797.9 | 220.9 | 213.4 | | TH (mg/L) | 4.9 | 1040.8 | 135.3 | 124.0 | 6.9 | 1040.8 | 169.2 | 135.1 | 4.9 | 329.5 | 72.7 | 64.1 | 10.0 | 362.3 | 95.1 | 97.6 | | K+ (mg/L) | 0.2 | 119.9 | 18.3 | 19.9 | 0.4 | 119.9 | 21.2 | 20.6 | 0.3 | 116.8 | 13.3 | 17.7 | 0.2 | 30.0 | 10.6 | 10.8 | | Na+ (mg/L) | 0.5 | 1008.8 | 36.4 | 88.4 | 1.5 | 1008.8 | 47.2 | 108.2 | 0.5 | 85.5 | 17.5 | 17.6 | 1.8 | 47.4 | 13.4 | 12.7 | | Ca2+ (mg/L) | 1.6 | 262.5 | 42.4 | 37.5 | 2.0 | 262.5 | 52.8 | 40.0 | 1.6 | 114.8 | 23.2 | 21.8 | 2.4 | 122.6 | 30.9 | 33.2 | | Mg2+ (mg/L) | – | 118.5 | 7.0 | 11.7 | 0.2 | 118.5 | 8.9 | 13.8 | – | 42.2 | 3.5 | 4.3 | 0.7 | 13.6 | 4.3 | 4.0 | | (mg/L) | 2.9 | 748.1 | 126.8 | 134.2 | 2.9 | 748.1 | 161.5 | 146.8 | 3.0 | 426.8 | 63.4 | 73.2 | 3.0 | 368.5 | 82.3 | 103.6 | | Cl− (mg/L) | 2.2 | 2042.8 | 58.5 | 163.4 | 3.5 | 2042.8 | 76.0 | 201.1 | 2.2 | 122.3 | 27.6 | 27.1 | 5.3 | 57.3 | 21.7 | 16.5 | | (mg/L) | – | 324.3 | 30.5 | 37.8 | – | 324.3 | 39.1 | 42.0 | – | 132.4 | 14.1 | 20.7 | – | 75.8 | 25.4 | 28.3 | | (mg/L) | – | 333.5 | 31.4 | 35.3 | – | 333.5 | 32.6 | 36.7 | – | 153.9 | 30.1 | 33.5 | 0.6 | 53.5 | 19.8 | 19.4 | | (mg/L) | – | 33.20 | 0.44 | 2.18 | – | 33.20 | 0.62 | 2.68 | – | 4.73 | 0.12 | 0.54 | – | 0.08 | 0.02 | 0.03 | | (mg/L) | – | 9.86 | 0.63 | 1.48 | – | 9.86 | 0.82 | 1.65 | – | 8.36 | 0.26 | 1.03 | – | 3.35 | 0.44 | 0.98 | | F− (mg/L) | – | 1.29 | 0.13 | 0.15 | – | 1.29 | 0.15 | 0.17 | – | 0.61 | 0.09 | 0.10 | – | 0.37 | 0.09 | 0.11 | | I− (mg/L) | – | 1.62 | 0.04 | 0.12 | – | 0.66 | 0.04 | 0.08 | – | 1.62 | 0.03 | 0.18 | – | 0.03 | 0.01 | 0.01 | | (mg/L) | – | 60.00 | 1.04 | 4.74 | – | 60.00 | 1.55 | 5.85 | – | 2.40 | 0.13 | 0.37 | – | 1.12 | 0.14 | 0.33 | | Fe (mg/L) | – | 41.10 | 0.55 | 2.69 | – | 41.10 | 0.75 | 3.30 | – | 8.07 | 0.20 | 0.75 | – | 0.52 | 0.13 | 0.15 | | Mn (mg/L) | – | 3.41 | 0.23 | 0.48 | – | 3.41 | 0.30 | 0.55 | – | 2.84 | 0.11 | 0.30 | 0.01 | 0.21 | 0.06 | 0.06 | | Al (mg/L) | – | 6.83 | 0.20 | 0.61 | – | 6.83 | 0.21 | 0.68 | – | 3.14 | 0.19 | 0.52 | – | 0.20 | 0.08 | 0.06 | | As (mg/L) | – | 0.3030 | 0.0050 | 0.0243 | – | 0.3030 | 0.0072 | 0.0301 | – | 0.0210 | 0.0010 | 0.0027 | – | 0.0025 | 0.0004 | 0.0007 |
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SD: standard deviation; –: below the limit of detection.
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