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| Effects of the combined application of silkworm excrement and sepiolite on Cd bioavailability in rhizosphere soil and Cd accumulation in grains of rice |
| Received:December 05, 2020 |
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| KeyWord:silkworm excrement;combined passivation;polluted paddy fields in mining areas;bioavailability of rhizosphere Cd;enrichment extraction;grain Cd accumulation |
| Author Name | Affiliation | E-mail | | LIU Shun'ao | College of Agriculture, Guangxi University, Nanning 530004, China
Agricultural Resource and Environment Research Institute, Guangxi Academy of Agricultural Sciences, Nanning 530007, China | | | HU Junming | Agricultural Resource and Environment Research Institute, Guangxi Academy of Agricultural Sciences, Nanning 530007, China | jmhu06@126.com | | WU Hao | Environmental Protection Research Institute of Guangxi, Nanning 530223, China | | | LIN Dasong | Agro-Environmental Protection Institute, Ministry of Agriculture and Rural Affairs, Tianjin 300191, China | | | ZHANG Junhui | Agricultural Resource and Environment Research Institute, Guangxi Academy of Agricultural Sciences, Nanning 530007, China | | | LI Tingting | Agricultural Resource and Environment Research Institute, Guangxi Academy of Agricultural Sciences, Nanning 530007, China | | | WEI Xianghua | College of Agriculture, Guangxi University, Nanning 530004, China | xhwfd@gxu.edu.com | | JIANG Xin | College of Agriculture, Guangxi University, Nanning 530004, China
Agricultural Resource and Environment Research Institute, Guangxi Academy of Agricultural Sciences, Nanning 530007, China | | | LIU Bin | Agricultural Resource and Environment Research Institute, Guangxi Academy of Agricultural Sciences, Nanning 530007, China | |
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| Abstract: |
| Treatment of heavy metals in paddy field soil in mining areas is of great significance to rice food security. This study aimed to explore the ecological remediation effect of silkworm excrement combined with sepiolite on Cd-contaminated paddy soil in mining areas, and to clarify treatment effects on Cd bioavailability in rice rhizosphere soil, Cd enrichment in different parts of the plants, and rice safety. For in-situ soil remediation tests in the paddy field, early rice was treated with silkworm excrement + sepiolite(T1), silkworm excrement + sodium humate + sepiolite(T2), silkworm excrement(T3), and a control(CK) without any modifier, whereas late rice was subjected to the aging test to assess treatment effects. The gradient diffusion film(DGT) technique was used to study the bioavailability of Cd in rhizosphere soil of the paddy field, and the correlation between Cd accumulation in different parts of the rice plant and in the grains was evaluated. The results showed that the bioavailability of Cd in rhizosphere soil of Cd-polluted paddy fields was reduced by treatment with silkworm excrement and other materials. Compared with CK, the T1, T2, and T3 treatments decreased bioavailability significantly in early rice by 88.36%, 82.00%, and 74.18%, respectively, and by 29.71% in the T3 treatment of late rice. The combined application of silkworm excrement and sepiolite reduced Cd uptake by rice, and the Cd content in the roots, stalks, leaves, chaff, and grains of rice decreased by 31.71%~55.54%, 17.01%~84.60%, 18.21%~57.09%, 44.94%~49.69%, and 47.62%~53.84%, respectively. The combined application of silkworm excrement and sepiolite improved soil physical and chemical quality. Soil pH, electrical conductivity, and soil organic matter increased from 0.13 to 0.27, 16.45% to 121.54%, and 15.51% to 39.64%, respectively. The Cd content of rice grains reached the safety level in the experiment on the aging effect of sepiolite, and met the relevant standards of National Food Safety Standard Limits for Pollutants in Food(GB 2762-2017). The lasting effect on Cd-pollution in paddy field was the longest. The combined passivation of sepiolite and silkworm excrement can effectively prevent and control the transfer of Cd between soil and rice, and can be used as an applied technology for the ecological regulation of Cd pollution in paddy fields. |
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