Comparative Use of Soil Organic and Inorganic Amendments in Heavy Metals Stabilization

Table 4

Sequential extraction procedure of heavy metals from soil samples and operationally defined fractions.

Phase/association	Abbr.	Step	Operational procedure
Soluble—exchangeable	EX	1	30 mL 0.1 M CaCl2, shaken 16 h at room temperature
Organic matter—bound	OB	2	30 mL 0.5 M NaOH, shaken 16 h at room temperature
Carbonates—bound	CB	3	30 mL 0.5 M Na2EDTA, shaken 1h
Residual	RES	4	Estimated by summation of three fractions and the total content (acid digestion with hydrochloric, sulfuric, and nitric acids) [1]