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Prediction model for cadmium concentrations in rice grain under the geochemical background of a cadmium anomaly area in Guangxi
Received:June 29, 2019  
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KeyWord:cadmium anomaly area;rice;stepwise multiple regression;fitting model;Guangxi
Author NameAffiliationE-mail
SONG Bo College of Environmental Science and Engineering, Guilin University of Technology, Guilin 541004, China  
WANG Fo-peng College of Environmental Science and Engineering, Guilin University of Technology, Guilin 541004, China  
ZHOU Lang College of Environmental Science and Engineering, Guilin University of Technology, Guilin 541004, China  
PANG Rui College of Environmental Science and Engineering, Guilin University of Technology, Guilin 541004, China  
WU Yong College of Earth Sciences, Guilin University of Technology, Guilin 541004, China  
CHEN Tong-bin College of Environmental Science and Engineering, Guilin University of Technology, Guilin 541004, China chentb@igsnrr.ac.cn 
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Abstract:
      To understand the effect of soil cadmium(Cd)on the Cd concentrations in rice grain a large-scale study was conducted in Guangxi under the geochemical background of a Cd anomaly area, rather than evaluating the Cd effect in an identified area. Stepwise multiple regression analysis was used to establish the prediction model for Cd content in rice grain under different Cd concentrations based on a total of 656 soil and rice samples. The results showed that soil in the study area was neutral(average pH value:6.8)and could be classified as mineral soil(organic matter mean:39.53 g·kg-1); the total Cd and available Cd content ranged from 0.078 to 7.893 mg·kg-1 and from 0.028 to 5.875 mg·kg-1, respectively. According to the "Food Safety National Standards for Contaminants in Foods"(GB 2762-2017), the over-standard rate of Cd in rice grain was 13.6%. The most suitable prediction models of different Cd concentration grades were:G1(<0.5 mg · kg-1):lg(Cd-G)=1.561-3.782 lg(pH)+1.825 DTPA-Cd; G2(0.5~1.0 mg · kg-1):lg(Cd-G)=5.145-0.280 pH-2.448 lg(OM)+ 1.039 lg (DTPA-Cd); G3 (1.0~2.0 mg·kg-1):lg (Cd-G)=1.074-0.208 pH-0.029 OM+0.589 DTPA-Cd; G4 (2.0-3.0 mg·kg-1):lg (Cd-G)=-0.897-0.026 OM+0.785 DTPA-Cd; G5(>3.0 mg·kg-1):lg(Cd-G)=0.791-1.322 lg(OM). In general, the Cd concentration in Guangxi was relatively high, resulting in a significant impact on the food safety of rice planting. These prediction models effectively describe the Cd content of rice grain in the study area, which could help to determine Cd accumulation in rice in the Cd anomaly areas of Guangxi.