Relationship between Cadmium Fractions Obtained by Sequential Extraction of Soil and the Soil Properties in Contaminated and Uncontaminated Paddy Soils

Table 3

Correlation between proportions of Cd chemical forms and soil properties^a.

Soil properties	Uncontaminated soils					Contaminated soils
	Exchangeable	Inorganically bound	Organically bound	Oxide occluded	Residue	Exchangeable	Inorganically bound	Organically bound	Oxide occluded	Residue
pH(H2O)	(−)
pH(KCl)	(−)	(+)				(−)	(+)
T-C						(−)		(+)
T-N						(−)		(+)
CEC						(−)	(+)	(+)
Ex-Ca						(−)	(+)			(+)
Ex-Mg						(−)	(+)
Ex-K
Base saturation	(−)						(+)
Available phosphate	(−)	(+)				(−)		(+)
PAC						(−)	(+)	(+)
Free iron oxide
Sand						(+)	(−)			(−)
Silt							(+)			(+)
Clay										(+)
Alo + 1/2 Feo^b						(−)	(+)	(+)

(+): positive correlation, (−): negative correlation, (), (), and ().
^bExtracted with acid oxalate.