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| Effects of combined passivating agents on remediation of Cd and Pb compound-contaminated soil |
| Received:July 09, 2018 |
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| KeyWord:soil;pakchoi;combined passivating agents;Cd-Pb compound pollution |
| Author Name | Affiliation | | ZHANG Di | School of Environmental Science, Nanjing Xiaozhuang University, Nanjing 211171, China | | DING Ai-fang | School of Environmental Science, Nanjing Xiaozhuang University, Nanjing 211171, China |
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| Abstract: |
| To understand the influence of combined passivating agents (nano-hydroxyapatite:mercaptobentonite:biochar=1:2:2) on the remediation of Cd and Pb compound-contaminated soil (Cd:0.89~1.37 mg·kg-1, Pb:441.9~707.8 mg·kg-1), using Cd-Pb contaminated soils collected from vegetable bases in Nanjing, a pot experiment was carried out to investigate the effects of different amounts of the combined passivating agents (0, 0.5%, 1%, 2.5%, and 5%) on the soil physical and chemical properties, contents of available Cd and Pb in the tested soils, and accumulation and translocation of Cd and Pb in pakchoi (Brassica chinensis L.). The results indicated that the application of combined passivating agents can effectively increase the soil pH and cation exchange capacity, and significantly decrease the contents of available Cd and Pb in the tested soils. Furthermore, the concentrations of Cd and Pb in the edible parts and roots of pakchoi decreased obviously. Compared with those in the control treatment, the maximum degrees of reduction for the Cd and Pb contents were 60.34%~63.83% and 81.84%~85.19%, respectively. The contents of Cd and Pb in the edible parts of pakchoi decreased by 64.44%~81.48% and 80.07%~82.98%, respectively. It was found that the bioaccumulation capacity of pakchoi was greater for Cd than that for Pb. The accumulation and translocation of Cd and Pb in pakchoi decreased significantly when the amount of passivating agent was 2.5%~5%. The application of combined passivating agents can significantly decrease the effectiveness of Cd and Pb in the tested soil, and thus decrease the accumulation of Cd and Pb in the edible parts of pakchoi. From the perspective of food safety, the recommended application rate for soil A was 5%, and that for soil B was 2.5%. |
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