Extraction by barium salts of heavy metals from two chilean soils

Abstract

Extraction of Cd,Cu, Ni and Zn by BaCl(Ba(ClO-4)2 solutions from El Recuerdo(Vertisol) and Puerto Octay (Andept)soils was used to measure the amounts of metals remaining extractable during a 60-d storage period under air-dry and wet conditions. The El Recuerdo soil with an original pH of 7.3 sorbed about twice the amounts of metals sorbed by the Puerto Octay soil with an original pH of 5.5. The percent of the sorbed metal that remained extractable was in the order of Cd > Ni > Zn > for El Recuerdo but Ni > Cd > Zn > Cu for for the Puerto Octay soils. The decrease in pH associated with metal sorption was greatest fo Cu which also showed the maximum fixation against extraction with Ba. The amounts of metals remaining extractable generally decreased with time, indicating that fixation reactions were essentially complete in 15 d in most cases and continued beyond the 15-d period in a few cases. The BaCl2 solution desorbed more Cd than Ba(ClO4)2 but this effect of anion was not shown for the other metals, which agrees with the fact that the other metals. Only small and inconsistent differences were found for storage in air-dry as compared to wet conditions.