Table 3 Average value of response factors, background value of heavy metals in regional soil and limitation of heavy metals in soil and food (mean ± SD, mg kg−1).
Sampling sites | Average value | Cd | Pb | Cu | Zn |
|---|---|---|---|---|---|
Maize | Total concentration in soil | 0.342 ± 0.177 | 25.794 ± 5.631 | 29.118 ± 3.515 | 66.633 ± 8.196 |
DTPA extraction in soil | 0.103 ± 0.054 | 1.847 ± 0.561 | 3.693 ± 0.616 | 8.293 ± 1.268 | |
Concentration in roots | 0.189 ± 0.098 | 0.273 ± 0.079 | 28.982 ± 3.852 | 59.782 ± 8.289 | |
Concentration in edible parts | 0.050 ± 0.029 | 0.088 ± 0.027 | 15.938 ± 2.266 | 50.232 ± 6.801 | |
Pakchoi | Total concentration in soil | 0.555 ± 0.157 | 33.965 ± 3.379 | 41.145 ± 10.172 | 98.87 ± 28.656 |
DTPA extraction in soil | 0.163 ± 0.053 | 2.847 ± 0.502 | 4.967 ± 0.999 | 12.087 ± 4.258 | |
Concentration in roots | 0.478 ± 0.128 | 1.217 ± 0.167 | 45.249 ± 10.536 | 96.06 ± 28.593 | |
Concentration in edible parts | 0.135 ± 0.043 | 0.218 ± 0.032 | 30.973 ± 7.857 | 83.682 ± 23.674 | |
Background value in regional soil42 | 0.084 | 25.8 | 24.0 | 63.5 | |
Risk screening values for heavy metals of farmland in China3 | 0.6 | 170 | 100 | 300 | |
Limitation of heavy metals for food in China43 | Maize | 0.1 | 0.2 | – | – |
Pakchoi | 0.2 | 0.3 | – | – |
