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| Using thiolated palygorskite to remediate Cd-contaminated alkaline soil via rapid immobilization |
| Received:September 14, 2020 |
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| KeyWord:cadmium;immobilization;thiolated palygorskite;alkaline soil;pakchoi;lettuce |
| Author Name | Affiliation | E-mail | | HE Li-zhi | Key Laboratory of Original Environmental Pollution Control of MARA, Agro-Environmental Protection Institute, Ministry of Agriculture and Rural Affairs, Tianjin 300191, China | | | XU Ying-ming | Key Laboratory of Original Environmental Pollution Control of MARA, Agro-Environmental Protection Institute, Ministry of Agriculture and Rural Affairs, Tianjin 300191, China | | | SONG Chang-zhi | Key Laboratory of Original Environmental Pollution Control of MARA, Agro-Environmental Protection Institute, Ministry of Agriculture and Rural Affairs, Tianjin 300191, China | | | WU Yi-qian | School of Engineering and Technique, Tianjin Agricultural University, Tianjin 300384, China | | | HUANG Qing-qing | Key Laboratory of Original Environmental Pollution Control of MARA, Agro-Environmental Protection Institute, Ministry of Agriculture and Rural Affairs, Tianjin 300191, China | | | LIANG Xue-feng | Key Laboratory of Original Environmental Pollution Control of MARA, Agro-Environmental Protection Institute, Ministry of Agriculture and Rural Affairs, Tianjin 300191, China | liangxuefeng@caas.cn |
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| Abstract: |
| To investigate the applicability and potential of thiolated palygorskite as an immobilization amendment for Cd-contaminated alkaline soil, pot experiments were conducted with pak choi and lettuce as model plants cultivated in Cd-contaminated alkaline soil. These tests were combined with soil incubation experiments were conducted to investigate the rapid immobilization effect of thiolated palygorskite on the Cd in alkaline soil. Results showed that applications of thiolated palygorskite at dosages of 0.1%~0.3% could reduce Cd concentration by 81.44%~93.44% and 68.47%~85.63%, respectively, in the shoots and roots of pakchoi during its growth period. The Cd concentrations in the shoots and roots of lettuce decreased by 65.11%~92.18% and 57.77%~91.92%, respectively. The Cd concentration in the edible parts of the mature plants satisfied the maximum permitted level of the national standard, with another great advantage of thiolated palygorskite being a significant immobilization effect even at trace application dosages. Thiolated palygorskite can reduce DTPA (diethylene triamine pentaacetic acid)extractable Cd concentrations in the soil by 68.57%~84.10% in a rapid immobilization process that reached equilibrium at approximately 5 d; this could be fitted with second-order kinetics. Sequential extraction analysis showed that thiolated palygorskite quickly reduced the concentrations of exchangeable and carbonate-bound Cd in alkaline soil and significantly increased the concentrations of the easily reducible metal oxide-bound Cd, thereby promoting the transformation of Cd from active species to non-active fractions and thus reducing its accumulation in the edible parts of plants. Thiolated palygorskite also simultaneously inhibited Cd transport factor and biological accumulation coefficient in both pakchoi and lettuce. This study thus confirms that thiolated palygorskite is an efficient immobilization amendment with a good potential for application in Cd-contaminated alkaline soil. |
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