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| The characteristics and potential risk of heavy metals pollution in farmland soil of an agricultural land in the Three Gorges Reservoir area |
| Received:June 30, 2018 |
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| KeyWord:Three Gorges Reservoir area;farmland soil;heavy metals;Nemerow pollution index method;potential ecological risk index;risk assessment |
| Author Name | Affiliation | | WANG Jin-xia | Chongqing Vocational Institute of Engineering, Chongqing 402260, China | | LUO Le | Chongqing Vocational Institute of Engineering, Chongqing 402260, China | | CHEN Yu-cheng | Resource and Environment Sciences, Southwest University, Chongqing 400715, China | | HE Qing-ming | Taizhou University, Taizhou 225300, China | | ZHAN Ling-ling | Chongqing Vocational Institute of Engineering, Chongqing 402260, China |
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| Abstract: |
| In order to understand the characteristics and potential risks of heavy metal pollution in the agricultural activity areas of the Three Gorges Reservoir area, grids were placed within the study area and the center of each grid was chosen as a soil sampling point. Soil samples were collected at a distance from the soil surface, and a total of 82 soil samples were collected. Subsequently, the pollution levels of As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn in farmland soils were analyzed. In conjunction with the single factor pollution index, the Nemerow pollution index method, and the potential ecological risk index, the status of pollution and potential ecological risks in the study area were evaluated. The results showed that except for As, Hg, and Ni, the average values of the mass fractions of the other six heavy metals were all higher than their background values in the agricultural soil of the Three Gorges Reservoir area by 1.43~2.54 fold, thereby indicating the presence of different degrees of heavy metals accumulation of Cd, Cr, Cu, Hg, Pb, and Zn in the soil of the study area. In particular, the content at 12.20% of Cu sampling points exceeded the risk screening values for soil contamination of agricultural land in the Environmental Quality Standard for Soil. The PN values of the Nemerow comprehensive pollution index were Cu (1.01) > Cr (0.81) > Cd (0.62) > Zn (0.52) > Pb (0.45) > Ni (0.32) > As (0.29) > Hg (0.09), thereby indicating that the pollution level of Cu was light pollution, the pollution level of Cr was warning level, and that of the remaining six heavy metals was safety level. Nevertheless, in terms of the single potential ecological risk index (Eri), the average values were Hg (41.33) > Cd (36.71) > As (12.20) > Cu (6.54) > Pb (5.32) > Ni (4.72) > Cr (2.42) > Zn (1.14). Among them, the Eri value of Hg was above 40 and its risk level was medium, while the risk levels of other heavy metals were all low. In the study area, the comprehensive potential ecological risk index (RI) ranged from 68.57 to 143.57, with an average of 110.37. The comprehensive potential ecological risk level was low, but the RI values of 7.13% of soil samples were greater than 135 and were at a medium risk level. In summary, although the farmland soil in certain regions of the study area was contaminated by Cu at this stage, the overall risk of the soil in the study area was at a safe level and was in line with the Environmental Quality Standard for Soil for the production of agricultural products. The comprehensive potential ecological risk of heavy metals in the soil was low, and the potential ecological hazards mainly came from Hg and Cd. |
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