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| Effects of water management and amendments with iron and silicon-rich material and biochar on cadmium uptake of different rice varieties and their preliminary mechanisms |
| Received:October 23, 2018 |
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| KeyWord:water management;iron-silicon material;biochar;rice variety;brown rice Cd |
| Author Name | Affiliation | E-mail | | LUO Xiao-li | School of Geography and Planning, Sun Yat-sen University, Guangzhou 510275, China | | | JU Lin | School of Geography and Planning, Sun Yat-sen University, Guangzhou 510275, China | | | YAO Ai-jun | School of Geography and Planning, Sun Yat-sen University, Guangzhou 510275, China
Soil Remediation Research Center of SYSU-Zhisheng, Guangzhou 510275, China | yaoaijun@mail.sysu.edu.cn | | LIU Chong | School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, China | | | YANG Yan-hua | School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, China
Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou 510275, China | | | CAO Jian | Soil Remediation Research Center of SYSU-Zhisheng, Guangzhou 510275, China | | | TANG Ye-tao | School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, China
Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou 510275, China
Soil Remediation Research Center of SYSU-Zhisheng, Guangzhou 510275, China | | | QIU Rong-liang | School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, China
Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou 510275, China
Soil Remediation Research Center of SYSU-Zhisheng, Guangzhou 510275, China | |
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| Abstract: |
| Safe food production on large areas of paddy soils that were polluted with Cd at low to medium levels is crucial for human health. The effects of three water management modes, drought(D), intermittent flooding(IF), and continuous flooding(CF)as well as the combined application of water management and amendments with iron and silicon-rich material(IS)and biochar(B)on Cd uptake by different rice varieties were investigated through a field experiment. The possible phytoexclusion mechanisms involved were discussed. The results showed that the Cd content in brown rice treated by CF from tillering to maturity stage was reduced by 0.2%~45.43% compared with IF treatment and by 37.67%~62.11% compared with D treatment. Under the three water management modes, the Cd content in the low cumulative brown rice cultivar G8 2168 was 35.03%~54.61% lower than that in the conventional variety. Under the conditions of the three modes of water management(D, IF, and CF), the contents of Cd in brown rice treated with IS amendment decreased by 64.26%, 55.74% and 38.14%, respectively, compared with that treated with only water management. The effect of the combined amendment IS+B was significantly weaker. The lowest Cd content in brown rice was obtained with the combined application of low cumulative rice varieties, continuous flooding, and IS. Furthermore, the content of Cd in rice root iron plaque varied depending on the water management mode in the following order D < IF < CF, while the content of Cd in root and brown rice showed the inverse pattern(D > IF > CF). This indicated that continuous flooding could promote the fixation of Cd by root iron plaque which acted as a barrier for Cd entering the rice plants. However, continuous flooding also decreased significantly the soil available Cd concentrations(extracted by 0.01 mol·L-1 CaCl2). Thus, both mechanisms contributed to reducing the Cd uptake by rice. Iron and silicon-rich material addition had no significant effect on the content of Cd fixed by root iron plaque. It reduced the rice Cd uptake mainly by significantly decreasing the Cd availability in the soil. Therefore, the combined application of a low Cd cumulative rice variety, continuous flooding and IS can guarantee safe rice production on paddy soils with low to medium Cd pollution. Planting low Cd-cumulative rice cultivars, coupled with continuous flooding during the critical growth stage are very important to limiting Cd uptake by rice. The application of amendments and low Cd cumulative rice varieties should be favored in seasons or areas with a water shortage. |
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