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Effects of iron-silicon material and biochar on soil Cd and As speciation and vegetable uptake under simulated acid rain condition
Received:March 19, 2018  
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KeyWord:iron-silicon material;biochar;acid rain;cadmium and arsenic;speciation,bioavailability
Author NameAffiliationE-mail
GUO Juan School of Geography and Planning, Sun Yat-sen University, Guangzhou 510275, China  
LUO Xiao-li 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 yaoaijun@mail.sysu.edu.cn 
YUAN Ming School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275  
LIU Chong School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275  
TANG Ye-tao School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275
Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou 510275, China 
 
QIU Rong-liang School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275
Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou 510275, China 
 
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Abstract:
      A greenhouse pot experiment was conducted to study the effects of individual or combined treatments of iron-silicon material (IS), chicken manure(CM) and its biochar pyrolyzed at 350℃(B350) and 700℃(B700) on the soil Cd and As speciation and vegetable uptake under simulated acid rain condition. The results showed that the simulated acid rain led to a significant decrease in soil pH and increase in bioavailable Cd and As content in soil. The addition of amendments increased soil pH of 0.41~1.34 unit. Combined treatments of IS and biochar decreased soil bioavailable Cd and As contents significantly. The simulated acid rain significantly inhibited the growth of vegetable and promoted the accumulation of As and Cd in the edible parts of the vegetable. The simulated acid rain also caused adverse effect on the remediation of individual IS, CM and biochar, while combined treatments of IS and biochar could effectively resist the adverse effect of acid rain. Chemical speciation analysis of heavy metals in soil showed that acid rain treatment significantly increased the water soluble and exchangeable Cd, reduced the organic-bound/sulfide Cd and residual Cd. With the addition of combined treatment of IS and BC700, the soil water soluble and exchangeable Cd decreased significantly, while the iron-manganese oxide-bound, organic sulfide-bound Cd and the residual Cd increased, resulting in a significant decrease in Cd bioavailability. Combined treatment of IS and BC350 can significantly reduce the proportion of non-specifically adsorbed As in soil. The combined treatments of iron-silicon and biochar can effectively mitigate the toxic effects of As and Cd in farmland soils under acid rain or acidified conditions.