Immobilization of Pb by organic and inorganic phosphate and calcium sources in an acidic Pb-polluted soil amended with cow manure

Background: Chemical stabilization of heavy metals in acidic soil is one of the important points in environmental pollution. Thus, this research was conducted to investigate the effect of organic and inorganic amendments on lead (Pb) immobilization in the Pb-polluted soil. Methods: Treatments were consisted of applying cow manure (۰, ۱۵, and ۳۰ t/ha), and applying cow bone and phosphate rock (۵% (W/W)) in the Pb (۰, ۸۰۰, and ۱۶۰۰ mg Pb/kg soil)-polluted soil. The plant used in this experiment was canola. After ۷۰ days, the plants were harvested and soil and plant Pb concentration was measured using atomic absorption spectroscopy (AAS). Results: Applying ۱۵ and ۳۰ t/ha of cow manure in the Pb (۱۶۰۰ mg Pb/kg soil)-polluted soil significantly decreased the soil Pb concentration by ۱۴.۳ and ۱۷.۲%, respectively. For plant Pb concentration, it was increased by ۱۱.۸ and ۱۵.۱%, respectively. A significant decrease in plant Pb concentration was measured, when the soil under cultivation of the plant was amended with ۵% (W/W) phosphate rock powder. For the plants grown on the soil, which was amended with ۵% (W/W), the plant Pb concentration decreased by ۱۷.۶%. In addition, applying organic and inorganic amendment significantly decreased the bio-concentration factor (BCF), while the soil microbial respiration increased. Conclusion: The results of this study showed that applying ۱۵ and ۳۰ t/ha cow manure or calcium and phosphorus sources such as cow bone and phosphate rock powder (۵% (W/W) can decrease the soil Pb availability and prevent the Pb translocation from soil to plants.

Keywords:

Environmental pollution , Soil , Lead , Soil microbiology