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| Screening of cadmium passivator and its effect on the availability of medium and trace elements |
| Received:April 20, 2021 |
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| KeyWord:passivator;cadmium;medium and trace element;availability |
| Author Name | Affiliation | E-mail | | XIAO Kun | College of Resources and Environment, Southwest University, Chongqing 400715, China
Chongqing Key Laboratory of Agricultural Resources and Environment, Chongqing 400715, China | | | TIAN Xiaohui | College of Resources and Environment, Southwest University, Chongqing 400715, China
Chongqing Key Laboratory of Agricultural Resources and Environment, Chongqing 400715, China | | | JIANG Zhenmao | College of Resources and Environment, Southwest University, Chongqing 400715, China
Chongqing Key Laboratory of Agricultural Resources and Environment, Chongqing 400715, China | | | WEI Shiqiang | College of Resources and Environment, Southwest University, Chongqing 400715, China
Chongqing Key Laboratory of Agricultural Resources and Environment, Chongqing 400715, China | sqwei@swu.edu.cn |
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| Abstract: |
| This study investigated the effectiveness of 18 different passivators on cadmium(Cd) activity and medium trace elements availability in order to screen for an efficient passivator that can effectively inactivate Cd, while only having a slight impact on trace elements availability. An indoor test method was used where the test soil was the typical purple soil in Chongqing City. The effectiveness of these common passivators on Cd was compared, and highly effective passivators were selected to further investigate their impact on the availability of iron, manganese, copper, and zinc at different concentrations. The results showed that the passivation effectiveness of Cd in naturally contaminated soil with efficiencies > 47% occurred in the following descending order: biochar > calcium oxide > calcium hydroxide > silkworm fence > humic acid > zeolite, as per the recommended dosage. Furthermore, the passivation effectiveness of Cd in highly polluted soils with efficiencies > 72% occurred in the following descending order: calcium oxide > silkworm fence > biochar > calcium hydroxide > humic acid > zeolite. Most of the inorganic passivators in this study decreased the availability of the medium trace elements during the passivation of Cd. However, humic acid and the silkworm fence were able to maintain or increase the availability of iron, manganese, copper, and zinc. Based on the influence of the passivator on the medium trace element availability, the recommended dosages of passivators were 3.2% zeolite, 1.5% humic acid, 2% biochar, 0.4% calcium oxide, 4% calcium hydroxide, and 4% silkworm fence. As such, it is recommended that the basic soil quality is considered and the available contents to supplement microelements are used; alternatively, other passivants may be utilized concurrently when applying passivation to treat heavy metal-contaminated soil. |
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