Table 4: The content of heavy metals in four study areas (mg/kg).
| Cd | Cu | Ni | Pb | Cr | Mn | Co | Se | ||
| Pingdi | Content | 0.03-0.14 | 4.37-11.34 | 4.57-16.91 | 6.17-35.12 | 32.49-69.14 | 150.9-479.9 | 2.09-4.64 | 0.17-0.36 |
| Mean | 0.1a | 8.323a | 10.7a | 16.9a | 55.5b | 318.7ab | 3.57a | 0.24ab | |
| CV(%) | 47.42 | 35.11 | 47.09 | 76.35 | 29.49 | 42.17 | 30.28 | 35.11 | |
| Over limit rate(%) | / | / | / | / | / | / | / | / | |
| Puan | Content | 0.04-0.96 | 12.51-24.82 | 14.7-20.73 | 11.48-81.39 | 57.09-68.08 | 385.2-695.7 | 6.11-7.45 | 0-0.65 |
| Mean | 0.29ab | 15.45b | 16.48b | 26.23b | 61.5b | 585.5b | 6.68a | 0.31b | |
| CV(%) | 96.59 | 27.31 | 9.03 | 70 | 4.91 | 14.87 | 5.53 | 57.11 | |
| Over limit rate(%) | 16 | / | / | / | / | / | / | / | |
| Xingwen | Content | 0.1-0.23 | 11.21-18.24 | 17.31-26.3 | 0.64-0.91 | 15.9-18.87 | 185-351.2 | 9.5-13.2 | 0-0.36 |
| Mean | 0.17a | 12.8c | 19.48bc | 0.72cd | 17.22a | 260.6a | 10.85b | 0.18a | |
| CV(%) | 23.49 | 21.34 | 17.55 | 14.23 | 6.93 | 21.8 | 11.91 | 89.95 | |
| Over limit rate(%) | / | / | / | / | / | / | / | / | |
| Gulin | Content | 0.23-0.56 | 13.29-29.31 | 17.99-22.59 | 18.99-34.9 | 94.73-109 | 859-1721.1 | 9.56-13.35 | 0.5-1.16 |
| Mean | 0.43b | 22.14d | 20.3c | 25.3b | 102.5c | 1159.15b | 12.06c | 0.76c | |
| CV(%) | 23.54 | 28.79 | 6.67 | 4.55 | 17.47 | 26.38 | 8.79 | 33.61 | |
| Over limit rate(%) | 90 | / | / | / | / | 20 | / | 30 | |
Difference letters following mean values within the same column the same column indicate significant difference at p < 0.05 according to Duncan’s multiple range test.