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The assessment of contamination levels of heavy metals in arable land soil is significant to the yields and qualities of crops. The assess methods of Index of Geoaccumulation (Igeo) and Set Pair Analysis (SPA) are applied to assess the farmland soil heavy metals, which are As, Hg, Cr, Cd and Pb, pollution levels. The results indicate although the concentrations of Cd in different soil samples is relative lower, the pollution levels of Cd in soils are highest among the five heavy metals. The assess results obtained by the Igeo and SPA were similar with each other, and the SPA is a comprehensive assess method. However, the Igeo concerned the single pollution levels of each trace element in soil.

The assessment methods of heavy metals pollution in soil, which are Set Pair Analysis, Index of Geoaccumulation and Principal Component Analysis, have commented in this study. Set Pair Analysis can obtain the comprehensive contamination levels of heavy metals in soil based on the distribution of contents of heavy metals in research soil. Similar with the SPA, the method of Principal Component Analysis can assess the comprehensive pollution levels of heavy meals in soil, and can identify the main pollution factor in soil based on the eigenvalues of principal components and the concentration of heavy metals in soil. The technique of Index of Geoaccumulation is a single factor assessing methods, which reflect the relative pollution levels of each trace element in study area objectively. The combination of comprehensive assessing methods and single factor analysis can reflect the real pollution conditions of heavy metals in soil well.