Effects of calcium peroxide on arsenic uptake by celery (Apium graveolens L.) grown in arsenic contaminated soil.

The ability of calcium peroxide (CaO(2)) to immobilize As of contaminated soil was studied using pot and field experiments. In pot experiment, CaO(2) applied at 2.5 and 5 g kg(-1) significantly increased celery shoot weight and decreased shoot As accumulation, which was ascribed to the formation of stable crystalline Fe and Al oxides bound As and the reduction of labile As fractions in the soil. The labile As fractions were pH dependent and it followed a "V" shaped profile with the change of pH. In field experiment, the dose of CaO(2) application at 750 kg ha(-1) was optimal and at which the celery was found to produce the highest biomass (63.4 Mg ha(-1)) and lowest As concentration (0.43 mg kg(-1)). CaO(2) probably has a promising potential as soil amendment to treat As contaminated soils.