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| Characteristics and risk of heavy metals pollution in soils of the irrigation area of a large-scale pig farm: A case study of a pig farm in Chongqing, China |
| Received:December 29, 2017 |
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| KeyWord:soil;heavy metals;fraction distribution;pollution characteristics;ecological risk assessment |
| Author Name | Affiliation | E-mail | | YANG Lu | College of Urban Construction and Environmental Engineering, Chongqing University, Chongqing 400044, China | | | ZHANG Yu | China Municipal Engineering Xinan Design General Institute Co, Ltd, Chengdu 610081, China | | | ZHANG Zhi | College of Urban Construction and Environmental Engineering, Chongqing University, Chongqing 400044, China | zhangzhicqu@cqu.edu.cn | | LI Yu-jie | College of Urban Construction and Environmental Engineering, Chongqing University, Chongqing 400044, China | | | WENG Zhang-fan | College of Urban Construction and Environmental Engineering, Chongqing University, Chongqing 400044, China | | | SUN Lei | College of Urban Construction and Environmental Engineering, Chongqing University, Chongqing 400044, China | | | KONG Yuan | College of Urban Construction and Environmental Engineering, Chongqing University, Chongqing 400044, China | |
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| Abstract: |
| To evaluate the pollution characteristics and potential ecological risk of heavy metals in soil irrigated with piggery waste, 16 soil samples were collected from the irrigated area of a pig farm in Chongqing. The concentrations and fractions of Cu, Zn, Cd, and Pb in the soil samples were determined. Three assessment methods (Single-factor pollution index, Nemerow pollution index, Geoaccumulation index) were used to evaluate pollution characteristics of the heavy metals in the soil samples. The bioavailability and potential ecological risk of the heavy metals were measured based on fraction distribution of the heavy metals in the soil. The results showed that the average concentrations of Cu, Zn, Cd, and Pb in soil samples were 30.80, 91.33, 0.55 mg·kg-1, and 29.34 mg·kg-1, respectively. Although the average concentrations of the heavy metals exceeded the soil background values of Chongqing, they were all below their secondary standards for environmental quality of soils (GB 15618-1995). The variation coefficient of the heavy metals ranked as follows:Cd > Cu > Zn > Pb, and the variability of the Cd and Cu concentrations in the soil samples was high, with large variation coefficients. The content of Cd in some soil samples reached the level of medium pollution, whereas none of the soil samples was polluted by Cu, Zn, or Pb. The residual phase was the main fraction of Cu, Zn, and Pb, accounting for 85.52%, 68.40%, and 56.55%, respectively. Meanwhile, the main fraction of Cd was the reducible phase, which accounted for 52.65%. The bioavailability of the heavy metals ranked as follows:Cd > Zn > Pb > Cu. The bioavailable risk of Cd and Zn was higher than that of Cu and Pb. The results of individual potential ecological risk indicated that risk from Cu, Zn, Cd, and Pb in the soil samples was low, as calculated by the secondary standards for environmental quality of soils, whereas the ecological risk of Cd in the soil samples was medium, as calculated by the soil background value of Chongqing. In general, the ecological risk of the four heavy metals in the study area was low, according to the comprehensive potential ecological risk index. |
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