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| Effects of cadmium content in soil and stem base on the risk of cadmium contamination in rice |
| Received:March 17, 2020 |
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| KeyWord:rice;cadmium;elevation;soil depth;growing seasons;risk |
| Author Name | Affiliation | E-mail | | HUANG Yong-chun | Key Laboratory of Original Agro-Environmental Pollution Prevention and Control, Agro-Environmental Protection Institute, Ministry of Agriculture and Rural Affairs, Tianjin 300191, China | | | ZHANG Chang-bo | Key Laboratory of Original Agro-Environmental Pollution Prevention and Control, Agro-Environmental Protection Institute, Ministry of Agriculture and Rural Affairs, Tianjin 300191, China | | | REN Xing-hua | Xiangtan Agricultural Science Research Institute, Xiangtan 411134, China | | | WANG Pei-pei | Key Laboratory of Original Agro-Environmental Pollution Prevention and Control, Agro-Environmental Protection Institute, Ministry of Agriculture and Rural Affairs, Tianjin 300191, China | | | WANG Chang-rong | Key Laboratory of Original Agro-Environmental Pollution Prevention and Control, Agro-Environmental Protection Institute, Ministry of Agriculture and Rural Affairs, Tianjin 300191, China | | | LIU Zhong-qi | Key Laboratory of Original Agro-Environmental Pollution Prevention and Control, Agro-Environmental Protection Institute, Ministry of Agriculture and Rural Affairs, Tianjin 300191, China | liuzhongqi508@163.com |
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| Abstract: |
| Changes in the content of total Cd and bioavailable Cd in soil at different elevations and seasons were studied to explore the key factors influencing the risk of rice Cd-contamination and to compare the effectiveness of different classification methods in reduction of rice Cd-contamination risk. The results showed that elevation, rice growing season and Cd content in deep soil (40~60 cm)had significant effects on the level of Cd-contamination in surface soil (0~20 cm). The Cd content in soil of low altitude area was significantly higher than that of high altitude area. The Cd content in deep soil was relatively stable (0.11~0.60 mg·kg-1), and the Cd content in surface soil fluctuated greatly (0.22~1.78 mg·kg-1). The total Cd content was closely correlated with the content of bioavailable Cd, but had little influence on the occurrence rate of low Cd rice (Cd ≤ 0.2 mg·kg-1). With the increase of Cd content in soil, the occurrence rate of medium Cd rice (0.2 mg·kg-1-1)decreased significantly, and the occurrence rate of high Cd rice (Cd>0.8 mg·kg-1)increased significantly, which led to a sharp increase in the risk of rice Cd over 0.2 mg·kg-1. In the plain and downland areas with an elevation of 26~90 m, the Cd content in rice was negatively correlated with the elevation of the producing area, and the bioavailable Cd content in the low elevation area was significantly higher than that in the adjacent high elevation area. Content of rice Cd was significantly and positively correlated with the Cd content in roots and stem base parts. When the Cd content in stem base was less than 4.0 mg·kg-1, only 8.8% samples had rice Cd content over 0.4 mg·kg-1, and the average rice Cd content in all samples was 0.20 mg·kg-1. When the Cd content in stem base was more than 9.0 mg·kg-1, nearly all samples showed high Cd content (>0.8 mg·kg-1). Therefore, risk of rice Cd over 0.2 mg·kg-1 will not efficiently decrease if rice production areas are classified based on the Cd content of surface soil which is easily affected by agricultural activities and ecological factors. Alternatively, classifying rice fields based on the Cd content in stem base can effectively reduce the risk of rice Cd over 0.2 mg·kg-1. |
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