Investigate the Effect of Organic and Inorganic Amendments on Lead and Cadmium Bioavailability in calcareous soils

Abstract

Background and purpose: Increasing agricultural activities and subsequently releasing pollutants from agricultural systems as well as expanding industries cause heavy metals (lead and cadmium) to enter the environment. Application of amendments are suitable methods for the inactivation of heavy metals in contaminated soils. Materials and methods: In order to study the effect of organic amendments (bichar 640 and 420) and inorganic amendments (zeolite, bentonite, leca and pumice) on bioavailability of Pb and Cd during incubation time in a calcareous soil, a factorial experiment was conducted in a completely randomized design with 3 levels of amendments application in soil (0, 1 and 5 %) in three replications. Bioavailability of Pb and Cd in soil was determined using DTPA and EDTA- extractable during 90- and 180-days incubation time. Results: Results showed that concentration of DTPA-extractable Pb and Cd increased during the time. Application of biochar 640, bentonite and zeolite (5%) decreased concentration of EDTA-extractable Pb during the incubation time. Application of biochar (1%) were the most effective treatment in decreasing Pb concentration EDTA-exchangeable. Application of the organic amendments (biochar 640 and biochar 420) and inorganic amendments (pumice, leca bentonite, and zeolite) increased concentration of EDTA-extractable Cd during the incubation time. Application of 5% of zeolite showed the lowest increasing concentration of EDTA-extractable Cd during the incubation time. Conclusion: Organic amendments were more efficient in immobilization of Cd and Pb than the inorganic amendments. These results might due to the high amount of organic carbon and cation exchange capacity of the organic amendments than the inorganic amendments.

Keywords

• organic and inorganic amendments
• bioavailability
• lead
• cadmium