Table 3 Results of extractable heavy metals of rhizosphere soils, and the linear correlation coefficients (r 2) between metal concentrations in the edible part of the lettuces and extracted metals from soils by different extraction methods (S: control; SB: soil amended with B38; SC: soil amended with corn straw-derived biochar; SCB: soil amended with corn straw-derived biochar and B38; SP: soil amended with pig manure-derived biochar; SPB: soil amended with pig manure-derived biochar and B38) (n = 3).
Treatment | Extracted metal concentration (mg/kg) | r 2 | ||||||
|---|---|---|---|---|---|---|---|---|
S | SB | SC | SCB | SP | SPB | |||
DTPA | Cd | 0.88 ± 0.22 | 0.55 ± 0.06 | 0.48 ± 0.02 | 0.32 ± 0.05 | 0.45 ± 0.05 | 0.31 ± 0.08 | 0.84* |
Cr | 0.62 ± 0.07 | 0.38 ± 0.02 | 0.37 ± 0.02 | 0.33 ± 0.06 | 0.34 ± 0.04 | 0.38 ± 0.02 | 0.45 | |
Hg | 0.07 ± 0.02 | 0.04 ± 0.01 | 0.05 ± 0.01 | 0.04 ± 0.02 | 0.04 ± 0.02 | 0.03 ± 0.01 | 0.94** | |
Pb | 3.00 ± 0.13 | 2.61 ± 0.12 | 2.46 ± 0.17 | 2.17 ± 0.10 | 2.24 ± 0.13 | 2.00 ± 0.14 | 0.85* | |
M3 | Cd | 1.65 ± 0.08 | 1.38 ± 0.08 | 0.50 ± 0.09 | 0.48 ± 0.02 | 0.57 ± 0.03 | 0.40 ± 0.04 | 0.80 |
Cr | 6.10 ± 0.42 | 5.54 ± 0.56 | 5.70 ± 0.23 | 3.19 ± 0.21 | 5.32 ± 0.25 | 4.84 ± 0.13 | 0.25 | |
Hg | 0.08 ± 0.01 | 0.08 ± 0.02 | 0.07 ± 0.01 | 0.05 ± 0.03 | 0.07 ± 0.02 | 0.04 ± 0.02 | 0.49 | |
Pb | 2.41 ± 0.43 | 1.64 ± 0.32 | 1.01 ± 0.08 | 0.93 ± 0.08 | 1.03 ± 0.06 | 0.89 ± 0.03 | 0.93** | |
BCR1 | Cd | 1.53 ± 0.03 | 1.30 ± 0.12 | 1.38 ± 0.11 | 1.17 ± 0.08 | 1.37 ± 0.05 | 1.19 ± 0.04 | 0.63 |
Cr | 6.48 ± 0.07 | 6.18 ± 0.34 | 5.89 ± 0.18 | 5.14 ± 0.19 | 5.51 ± 0.26 | 4.71 ± 0.79 | 0.91** | |
Hg | 0.07 ± 0.02 | 0.07 ± 0.01 | 0.06 ± 0.02 | 0.06 ± 0.01 | 0.06 ± 0.02 | 0.05 ± 0.02 | 0.51 | |
Pb | 4.15 ± 0.11 | 2.75 ± 0.09 | 2.76 ± 0.03 | 1.19 ± 0.03 | 1.18 ± 0.22 | 0.99 ± 0.02 | 0.78 | |
