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| Investigations on the derivation of a safe wheat-producing threshold of soil Cd content and classification of Cd contaminated wheat-producing areas in northern China |
| Received:October 02, 2020 |
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| KeyWord:Cd;bioconcentration coefficient;quantitative relationship;threshold level;classification of wheat-producing area |
| Author Name | Affiliation | E-mail | | GUAN Wei-dou | College of Natural Resources and Environment, Northwest A&F University, Yangling 712100, China | | | XIAO Ran | College of Natural Resources and Environment, Northwest A&F University, Yangling 712100, China | | | LI Rong-hua | College of Natural Resources and Environment, Northwest A&F University, Yangling 712100, China | rh.lee@nwsuaf.edu.cn | | LIU Xiang-yu | College of Natural Resources and Environment, Northwest A&F University, Yangling 712100, China | | | Pan Jun-ting | Key Laboratory of Non-point Source Pollution Control, Ministry of Agriculture and Rural Affairs, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, China | | | HUANG Yong-chun | Agro-Enviornmental Protection Institute, Ministry of Agriculture and Rural Affairs, Key Laboratory of Agricultural Product Quality Safety Environmental Factor Control, Tianjin 300191, China | nylab@126.com | | ZHANG Zeng-qiang | College of Natural Resources and Environment, Northwest A&F University, Yangling 712100, China | | | GUO Di | College of Natural Resources and Environment, Northwest A&F University, Yangling 712100, China | |
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| Abstract: |
| In this study, 147 soil and wheat sample pairs were collected from six wheat-producing areas in northern China using a point-topoint collection method. To clarify the quantitative relationship between the Cd content in wheat grains and soil physicochemical properties, pH, Cd content, soil organic matter(SOM), cation exchange capacity(CEC), and clay content(Clay) were analyzed. The quantitative relationships between the physicochemical properties of soil and bioconcentration coefficient(BCF) of Cd in wheat grains were investigated through linear correlation and multiple regression analysis methods. Furthermore, the classification of wheat-producing areas as suitable yield, restricted yield, forbidden yield, and the associated soil Cd thresholds was derived using the species sensitivity distribution method for the safe production of wheat in different proportions from each divided area. The results showed that the farmland soil and wheat samples from the study area had some safety risks. It was determined that 95.1% of soil and 47.6% of wheat grains exceeded the Cd limits of soil and food standards. The soil pH, SOM and Clay contents were significantly correlated with BCF, with correlation coefficients of -0.18(P<0.05), 0.14(P<0.05), and -0.53(P<0.01), respectively. The regression model based on soil pH, SOM, and Clay content accounted for 54% of the variation in BCF. Based on the soil characteristics in northern wheat-producing areas, three typical scenarios, 6.5 ≤ pH<7.5(SOM=15 g·kg-1, Clay=20%)、7.5 ≤ pH<8.5(SOM=30 g·kg-1, Clay=20%) 和 pH ≥ 8.5(SOM=20 g·kg-1, Clay=20%) were set; the soil Cd thresholds for the suitable yield of wheat-producing areas were 0.33, 0.41 mg·kg-1, and 0.64 mg·kg-1, respectively, while, the thresholds for the forbidden yield of wheat-producing areas were 1.93, 2.51 mg·kg-1, and 2.61 mg·kg-1, respectively. The area with soil Cd content in the range of the suitable yield threshold and the forbidden yield threshold could be considered restricted for the wheat-producing area's yield. |
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