Immobilization of Cd, Zn, and Pb from Soil Treated by Limestone with Variation of pH Using a Column Test

Table 4

Results of sequential extraction of Cd, Pb, and Zn in soil sampled.

Fraction

Heavy metal (mg/kg)

Cd

Pb

Zn

F1^{a}

22.5 (27.2%)^{e}

1,395 (18.6%)^{e}

1,095 (22.8%)^{e}

F2^{b}

6.56 (7.95%)^{e}

548 (7.30%)^{e}

292 (6.06%)^{e}

F3^{c}

15.4 (18.6%)^{e}

4,074 (54.2%)^{e}

1,710 (35.6%)^{e}

F4^{d}

38.1 (46.2%)^{e}

1,495 (19.9%)^{e}

1,713 (35.6%)^{e}

Acid soluble fraction (soluble and exchangeable fraction and bound to carbonates). ^{b}Reducible fraction (bound to Fe/Mn oxides). ^{c}Oxidizable fraction (bound to organic matter and sulfides). ^{d}Residual fraction (aqua regia). ^{e}The values in parentheses are ratio of each extract to sum of each extraction.