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).
^bReducible fraction (bound to Fe/Mn oxides).
^cOxidizable fraction (bound to organic matter and sulfides).
^dResidual fraction (aqua regia).
^eThe values in parentheses are ratio of each extract to sum of each extraction.