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Acta Prataculturae Sinica ›› 2022, Vol. 31 ›› Issue (10): 99-109.DOI: 10.11686/cyxb2021394

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Evaluation of soil heavy metal pollution under different land use patterns in the eastern Qilian Mountains

Ning-gang SAI(), Juan QI(), Yan-wei JIA, Mei-mei CHE, Juan-di YANG, Xiao-juan WANG, Chang-lin XU   

  1. Gansu Agricultural University,College of Pratacultural Science,Key Laboratory of Grassland Ecosystem,Ministry of Education,Lanzhou 730070,China
  • Received:2021-11-01 Revised:2021-12-13 Online:2022-10-20 Published:2022-09-14
  • Contact: Juan QI

Abstract:

In this study we measured the levels of seven heavy metals in soils under different land uses in the eastern Qilian Mountains. By comparison with the background levels of soil elements on the Qinghai-Tibet Plateau, the degree of soil heavy metal pollution and the overall potential ecological risk was evaluated using the Nemero comprehensive pollution index and potential ecological risk coefficient. It was found that the average values of the seven measured heavy metal elements were higher than the background values. The average levels of Zn and Ni was higher at 196.67 mg·kg-1 and 74.28 mg·kg-1, respectively, these values being 3.20 and 3.00 times higher, respectively, than background values. Thus, it was concluded that an enrichment phenomenon of soil heavy metal elements is occurring. The Nemero comprehensive pollution index averaged for all land use categories was 2.84, which is classed as the pollution level is moderat. For farmland, the average pollution index was highest at 3.10, which is classified as a severe pollution level. The grassland pollution index was 2.71, and the wetland was lowest at 2.49, both of which are considered moderate pollution levels. The average comprehensive potential ecological risk coefficient for all land types was 94.31, with the risk coefficient of farmland being the highest (101.90), while that of grassland was 92.22 and that of wetland was 73.29. The coefficient of variation for Zn in all soil types was the lowest. The coefficient of variation of Cd was the highest.

Key words: Qilian Mountains, soil pollution, heavy metals, ecological risk assessment