Table 4.
Soil PTEs content statistics in freeze–thaw area of Tuotuo river
| As | Cd | Cr | Cu | Ni | Pb | Zn | Co | Mn | Ti | V | Sc | References | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| mg/kg | ||||||||||||||
| Tuotuo River freeze–thaw area | Minimum | 10.2 | 0.083 | 41.0 | 8.71 | 12.1 | 17.9 | 38.3 | 4.49 | 229 | 2231 | 33.2 | 3.92 | This study |
| Maximum | 157 | 2.18 | 110 | 87.2 | 48.4 | 584 | 582 | 17.0 | 1088 | 4024 | 118 | 16.1 | This study | |
| Mean | 32.0 | 0.29 | 66.0 | 17.3 | 27.8 | 49.2 | 88.5 | 9.18 | 515 | 3158 | 60.4 | 7.7 | This study | |
| Standard deviation | 23.1 | 0.24 | 11.9 | 7.77 | 7.51 | 52.0 | 57.7 | 2.57 | 155 | 472 | 15.8 | 2.3 | This study | |
| Median | 25.1 | 0.25 | 65.9 | 16.5 | 26.9 | 40.7 | 75.7 | 8.87 | 507 | 3098 | 58.1 | 7.4 | This study | |
| Coefficient variation | 72.2 | 79.8 | 18.0 | 44.8 | 27.0 | 106 | 65.2 | 28.0 | 30.1 | 14.9 | 26.3 | 29.8 | This study | |
| The risk screening values for China soil contamination (GB 15618–2018, pH > 7.5) | 25 | 0.6 | 250 | 100 | 190 | 170 | 300 | |||||||
| Geochemical baseline values of soil in Lhasa | 20 | 0.13 | 42 | 23 | 21 | 31 | 70 | 10 | 619 | 3320 | 67 | 9 | Cheng et al. (2014) | |
| Background values of soil in Tibet | 19.7 | 0.081 | 76.6 | 21.9 | 32.1 | 29.1 | 74 | 11.8 | 625 | 3400 | 76.6 | 10.2 | (1990) | |
| Chinese soils | 1.9 | 0.05 | 63 | 38 | 57 | 15 | 86 | 32 | 780 | 659 | 99 | 11 | Li (1994) | |
| Worldwide soils | 6.83 | 0.41 | 59.5 | 38.9 | 29 | 27 | 70 | 11.3 | 488 | 7038 | 129 | 11.7 | Kabata-Pendias (2011) | |
| Upper continental crust (UCC) | 4.8 | 0.09 | 92 | 28 | 47 | 17 | 67 | 17.3 | 774 | 3840 | 97 | 14.0 | Rudnick and Gao (2004) | |