| In order to understand the accumulation, migration, and transformation of heavy metals in soil and rice in Tongren, Guizhou Province, a total of 230 groups of paddy soil and corresponding rice samples were collected, and the physical and chemical properties of heavy metals and soil were tested. The rice samples were evaluated using the single-factor index method, and the safe planting zoning method was proposed in combination with soil environmental quality and food contaminant limits. The results showed that:① the average values of ω(As), ω(Cd), ω(Cu), ω(Hg), ω(Ni), and ω(Zn) in paddy soil were 12.94, 0.343, 30.53, 3.869, 30.32, and 110.0 mg·kg-1, respectively, when the pH was between 4.4 and 7.9. Among them, As, Cd, Hg, and Zn exceeded the standards of 11.7%, 10.9%, 53.0%, and 3.04% compared with the screening values in "Soil Pollution Risk Control Standards for Agricultural Land of Environmental Quality". ② The characterization values of ω(As), ω(Cd), ω(Cu), ω(Hg), ω(Ni), and ω(Zn) in rice were 0.056, 0.017, 1.445, 0.010, 0.215, and 17.59 mg·kg-1; compared with the national food safety standard (GB 2762-2017), the contents of As, Cd, and Hg in rice samples exceeded the standard by 15.7%, 3.04%, and 19.1%. As exceeded the standard point mainly distributed in Songtao County, and Hg was mainly distributed in Bijiang and Wanshan District. ③ The order of enrichment coefficient of rice was Zn > Cd > Cu > Hg > As=Ni, and the absorption and enrichment ability of rice for Zn was the strongest. ④ Most areas in the study area belong to the priority protection category. The safe utilization category is concentrated in the east of Tongren, whereas the strictly controlled category is scattered within Bijiang District, Wanshan District, and Jiangkou County. The study showed that there was heavy metal pollution in the soil in some areas of Tongren City, and the safe planting of rice also had certain risks. |
