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Phytoexclusion and In-situ Immobilization of Cadmium in Vegetable Field in Sewage Irrigation Region
Received:May 08, 2014  
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KeyWord:phytoexclusion;immobilization;low-cadmium-accumulating cultivar;Brassica chinensis;sepiolite;bentonite;chicken manure
Author NameAffiliationE-mail
WANG Lin Department of Pollution Control, Agro-environmental Protection Institute, Ministry of Agriculture, Tianjin 300191, China
Key Laboratory of Original Agro-environmental Quality, Ministry of Agriculture, Tianjin 300191, China
Tianjin Key Laboratory of Agro-environment & Agro-product Safety, Tianjin 300191, China 
 
QIN Xu Department of Pollution Control, Agro-environmental Protection Institute, Ministry of Agriculture, Tianjin 300191, China
Key Laboratory of Original Agro-environmental Quality, Ministry of Agriculture, Tianjin 300191, China
Tianjin Key Laboratory of Agro-environment & Agro-product Safety, Tianjin 300191, China 
 
XU Ying-ming Department of Pollution Control, Agro-environmental Protection Institute, Ministry of Agriculture, Tianjin 300191, China
Key Laboratory of Original Agro-environmental Quality, Ministry of Agriculture, Tianjin 300191, China
Tianjin Key Laboratory of Agro-environment & Agro-product Safety, Tianjin 300191, China 
ymxu1999@126.com 
SUN Yue-bing Department of Pollution Control, Agro-environmental Protection Institute, Ministry of Agriculture, Tianjin 300191, China
Key Laboratory of Original Agro-environmental Quality, Ministry of Agriculture, Tianjin 300191, China
Tianjin Key Laboratory of Agro-environment & Agro-product Safety, Tianjin 300191, China 
 
LIANG Xue-feng Department of Pollution Control, Agro-environmental Protection Institute, Ministry of Agriculture, Tianjin 300191, China
Key Laboratory of Original Agro-environmental Quality, Ministry of Agriculture, Tianjin 300191, China
Tianjin Key Laboratory of Agro-environment & Agro-product Safety, Tianjin 300191, China 
 
DONG Ru-yin Department of Pollution Control, Agro-environmental Protection Institute, Ministry of Agriculture, Tianjin 300191, China
Key Laboratory of Original Agro-environmental Quality, Ministry of Agriculture, Tianjin 300191, China
Tianjin Key Laboratory of Agro-environment & Agro-product Safety, Tianjin 300191, China 
 
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Abstract:
      Phytoexclusion and in-situ immobilization are two common techniques for remediation of soil heavy metals. In this study, a field experiment was carried out to compare remediation efficiency of these two techniques and their combination in cadmium(Cd) contaminated vegetable field in sewage irrigation region. The effects of sepiolite, bentonite and chicken manure on growth and Cd accumulation of a common cultivar(Hanlv) and a low-cadmium-accumulating cultivar of Brassica chinensis(Chuantianhuizi) were examined and the mechanism of Cd immobilization was also explored by soil Cd fractionation. Applying chicken manure significantly increased shoot biomass of both cultivars, with maximal increases of 42.8% and 127.8% for Hanlv and Chuantianhuizi, respectively. Addition of clay minerals didn′t significantly increase shoot biomass of two cultivars. Combined applications of clays and chicken manure significantly decreased shoot Cd concentrations of the common cultivar, with a maximal reduction of 50.5%, causing shoot Cd concentrations lower than the China Food Safety Standard for Cd of 0.2 mg·kg-1(GB 2762—2012). In all immobilization treatments, the shoot Cd concentration of low-cadmium-accumulating cultivar was significantly lower than the maximum level permitted by GB 2762—2012. Addition of chicken manure significantly decreased available Cd concentrations in soil, with a maximal reduction of 37.0%, but clay additions didn′t decrease soil available Cd concentrations. Clays and chicken manure could promote transformation of exchangeable Cd into residual or organic bound fractions, resulting in significant reduction of Cd bioavailability. To sum up, planting low-cadmium-accumulating cultivar in combination with applications of clay and chicken manure could produce safe vegetables in Cd contaminated fields of sewage irrigation region.