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| Effects of vermicompost on the migration and transformation of heavy metal cadmium in soil-rice systems |
| Received:January 31, 2020 |
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| KeyWord:vermicompost;cadmium;rice;paddy soil;accumulate |
| Author Name | Affiliation | E-mail | | ZHANG Xiao-xu | School of Environmental Science and Engineering, Yangzhou University, Yangzhou 225100, China | | | ZHANG Jia-wei | School of Environmental Science and Engineering, Yangzhou University, Yangzhou 225100, China | | | SUN Xing-xing | School of Environmental Science and Engineering, Yangzhou University, Yangzhou 225100, China | | | XU Yi-qun | School of Environmental Science and Engineering, Yangzhou University, Yangzhou 225100, China | | | XU Jian | School of Environmental Science and Engineering, Yangzhou University, Yangzhou 225100, China | xujian_yz@163.com | | ZHU Jing | School of Environmental Science and Engineering, Yangzhou University, Yangzhou 225100, China | |
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| Abstract: |
| To reduce Cd content in rice and to explore the effect of vermicompost(CV)on Cd absorption and accumulation in different crops of rice, a pot experiment was carried out to investigate the effects of CV on soil Eh value, pH value, fractionation of Cd in paddy soils, and Cd content in rice grains. The results show that CV can significantly reduce the Eh value of paddy soil. Moreover, it considerably reduced the pH of paddy soil at the tillering stage of rice. However, it had no significant effect after the crop entered the heading stage. The addition of CV changed the fraction of Cd in the crop. In the tillering stage, the environmentally active Cd content decreased significantly, except for the low addition of 6.3 g C·kg-1 soil. The larger the amount of CV added, the greater the decrease of Cd. In the heading stage of rice, an added CV of 41.3 g C·kg-1 soil had a significant reduction effect, and in the ripening stage, the content of Cd in each treatment group decreased drastically. The addition of CV significantly reduced the content of Cd in brown rice. The content of Cd in brown rice decreased by 48.08% when CV of 6.3 g C·kg-1 soil was added. When the amount of CV was increased to 16.3 g C·kg-1 soil, the Cd content of brown rice decreased to 0.157 mg·kg-1, meeting the national rice Cd control standard of less than 0.2 mg·kg-1. There was no significant difference in the content of Cd in brown rice among the groups with the increase in the amount of CV. The content of Cd in all parts of the rice plant decreased significantly in the whole growth period in 41.3 g C·kg-1 soil. While the Cd content showed no obvious pattern in the stem of the rice plant in the heading stage, the content of Cd in the roots, stems, and leaves of rice in other growth periods showed that the greater the amount of CV, the more obvious the effect. During the whole growth period, CV reduced the content of exchangeable Cd in the soil by decreasing the soil Eh, consequently reducing the amount of Cd absorbed by rice. |
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