Shanghai yufang yixue (Aug 2024)
Heavy metal pollution in rural soil and ecological risk in Wanzhou District, Chongqing
Abstract
ObjectiveTo analyze and assess the pollution levels of lead (Pb), cadmium (Cd), and chromium (Cr) in rural soils of Wanzhou District, Chongqing Municipality, and to provide data support for proposing relevant measures and suggestions.MethodsBased on the soil monitoring data from 2017 to 2021, the ecological risk assessment was conducted by applying the Soil Pollution Risk Control Standard for Agricultural Land of Soil Environmental Quality (for trial implementation) (GB 15168‒2018), the pollution index method and the potential ecological risk method.ResultsA total of 100 soil samples were collected, with pH values ranged from 3.50 to 8.30, and a mean value of 6.10. The mean values of Pb, Cd, and Cr in the soil were 25.2 mg·kg-1, 0.310 mg·kg-1, and 68.6 mg·kg-1, respectively. Except for Cr, the mean values of other elements exceeded the soil background values. Cd level had the largest coefficient of variation and uneven spatial distribution, with an overall exceedance rate of 30.0%. Pollution levels of Pb and Cr were generally at the alert level, while Cd was generally at a light pollution level. The proportion of Cd pollution levels was higher than that of Pb and Cr, and the difference was statistically significant (χ2=15.015, P=0.001). The Nemerow comprehensive pollution index in different townships ranged from 0.70 to 2.07, with a median value of 1.10, and was generally at a light pollution level. The potential ecological hazard risk of Cd was relatively high, and was generally at a mild level of hazard. The highest contribution rate in the comprehensive potential ecological hazard index was Cd, accounting for 84.1%.ConclusionThere is a certain degree of Cd pollution and mild ecological risk in rural soils of Wanzhou District. Monitoring and management of Cd pollution in rural soils of Wanzhou District, Chongqing Municipality, should be strengthened.
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