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Effects of rice-husk-derived biochar on the morphological transformation of Cd and Zn in mining area soils polluted by heavy metals
Received:January 30, 2018  
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KeyWord:rice-husk-derived biochar;heavy metal contamination;Zn;Cd;chemical form
Author NameAffiliationE-mail
LI Hong-da College of Natural Resources and Environment, Northwest A & F University, Key Laboratory of Plant Nutrition and the Agri-Environment in Northwest China, Ministry of Agriculture, Yangling 712100, China  
LI Yan Agricultural Environmental Protection Monitoring Station, Xi'an 710003, China  
ZHOU Wei College of Natural Resources and Environment, Northwest A & F University, Key Laboratory of Plant Nutrition and the Agri-Environment in Northwest China, Ministry of Agriculture, Yangling 712100, China  
LÜ Jia-long College of Natural Resources and Environment, Northwest A & F University, Key Laboratory of Plant Nutrition and the Agri-Environment in Northwest China, Ministry of Agriculture, Yangling 712100, China ljlll@nwsuaf.edu.cn 
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Abstract:
      Understanding the agroecological effects of rice-husk-derived biochar would provide a reference for its rational application in the remediation of heavy-metal-contaminated soil in mining areas. In the present study, a pot trial was carried out to study the effect of the addition of different concentrations of rice-husk-derived biochar (0, 5, 10, 20, 50, 100 g·kg-1) on the pH and CEC levels and the morphological transformation of Cd and Zn in heavy-metal-polluted soil. The results indicated that the addition of rice-husk-derived biochar elevated the soil pH and CEC levels by 0.18~0.29 units and 32.89% (5.68 cmol·kg-1), respectively. In addition, the weak-acid-extractable Cd and Zn were reduced by 21.88% and 19.63%, respectively, and the oxidation states of Cd and Zn were reduced by 24.12% and 18.62%, respectively. The reducible fractions of Cd and Zn decreased by 13.72% and 8.97%, respectively, but the residual fractions of Cd and Zn increased by 115.56% and 39.45%, respectively, compared to those of the control treatments. Overall, the application of rice-husk-derived biochar elevated the soil pH and CEC and promoted transformation of the weak-acid-extractable, oxidizable, and reducible fractions of Cd and Zn into chemically stable residual fractions, which could positively reduce the bioavailability of heavy metals in heavy-metal-polluted soil near mining areas.