EXTRACTABILITY OF POLLUTING ELEMENTS CD, CR, NI AND PB OF SOIL WITH 3 METHODS

A laboratory study was conducted to evaluate 3 different chemical methods in extracting Cd, Cr, Ni and Pb of soils with wide range in their properties. The methods studied were aqua regia, 0.5 N HNO3 and acid ammonium acetate-EDTA, pH 4.65 (AAAc-EDTA). The mean values of Cd, Cr, Ni and Pb extracted by aqua regia were 0.22, 53.2, 35.4 and 23.9 mg/kg [respectively]. The 0.5 N HNO3 extracted of the aqua regia extractable Cd on an average 77%, of Pb 54%, of Ni 8% and of Cr 3%. The respective percentages in case of the AAAc-EDTA extraction were 64% for Cd, 34% for Pb, 4.5% for Ni and 0.26% for Cr. Highest percentage of Cd and Pb were extracted of soils where the aqua regia extractable contents were highest. This may be considered as an indication that 0.5 N HNO3 and AAAc-EDTA could be successfully used in pollution studies.