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Effects of mixed chelators on the removal of heavy metals from contaminated soil and on the growth of plants
Received:February 02, 2020  
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KeyWord:soil washing;multi-heavy metal contaminated soil;mixed chelators;maize;Chinese cabbage
Author NameAffiliation
GUO Xiao-fang School of Environment and Safety, Taiyuan University of Science and Technology, Taiyuan 030024, China 
HAN Wei School of Environment and Safety, Taiyuan University of Science and Technology, Taiyuan 030024, China 
ZHAO Guo-hui School of Environment and Safety, Taiyuan University of Science and Technology, Taiyuan 030024, China 
ZHANG Gui-xiang School of Environment and Safety, Taiyuan University of Science and Technology, Taiyuan 030024, China 
HE Qiu-sheng School of Environment and Safety, Taiyuan University of Science and Technology, Taiyuan 030024, China 
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Abstract:
      Soil washing is an effective technology for the remediation of multi-metal-contaminated soil. This study investigated the changes in physicochemical properties, the concentration and fractions of heavy metals in the paddy field contaminated soil after using EDTA or mixed chelator(EDTA, GLDA, citric acid)washing. Subsequently, three types of crops were planted in the washed soil. The agricultural value of washed soil were evaluated by measuring the plant biomass and metal concentrations in the root and shoot of plants. The results indicated that the removal rates of Cd, Pb, Cu and Zn in soil by mixed chelator(MC)washing were 44.30%, 28.78%, 26.44% and 11.49%, respectively. The highest removal rate of heavy metals was obtained at the time of second washing. Thereafter, the removal rate decreased with the increase in washing times. Biomass of Chinese cabbage decreased in the washed soil, and the heavy metal concentrations in the Chinese cabbage increased in the washed soil. This suggested that the risk of heavy metals in the washed soil was high in vegetables such as Chinese cabbage. In comparison with the control, biomass of maize did not decrease, however, the concentration of Cd, Pb, and Zn in maize were significantly decreased in the washed soil. Moreover, shoots of the maize were safe for use in feed production. The available heavy metal contents in the MC-washed soil were lower than those in the EDTA-washed soil and had a low impact on the growth of the plant. Therefore, the MC is a useful and environmentally friendly chelator to remediate multi-metal-contaminated soil.