Soil Heavy Metal Pollution Evaluation Xianyangshi Different Old Apple

Shaanxi province is an important base of apple production in China, and the research of heavy metal pollution on apple trees has an important significance for soil pollution prevention of the base of apple trees and the apple industry development in the long term.Based on apple trees land field investigation in Xianyang. sample collection and indoor experiment and analysis, this paper takes use of a large number of experimental data and statistical analysis method to study the soil heavy metal elements and major elements of soil vertical distribution and variation of apple trees land in Xianyang.At the same time, with the Shaanxi province soil background value and black loessial soil background values for the standard, the application of the single factor index method, the Nemerow pollution index and the potential ecological risk index method are used to evaluate the degree of heavy metal pollution apple of trees land at different ages in Xianyang city, and the main conclusions and cognitions are described as follows:(1)In the soil of apple trees land in Xianyang, heavy metal element content in vertical distribution is obvious. The heavy metal element content in the upper part is high, and the content in the middle and lower part is low, which indicaties that the upper soil appeares the accumulation of heavy metals.(2) The changing rules of the content of soil heavy metals varying with the growth of tree’age is not obvious.That may be related to the early pollution of apple trees land cultivated before.(3) According to the Nemerow pollution index method and the method of potential ecological risk index, the soil of apple trees land in Xianyang have been polluted by heavy metal at different degrees. According to the Shaanxi province soil background values and black loessial soil background value evaluation, the apple trees at different age growth stages in the studied area are in low light pollution and potential ecological risk state.(4) Using different reference value evaluation of soil heavy metal environmental, its effect is different. The results evaluated by Nemerow pollution index and the potential ecological risk index methods are not influrenced, but sinificantly influrenced by the single factor index. With Shaanxi province soil background values for the standard,6sample plots were subjected to pollution of heavy metals such as Co, Cr, Cu, Mn, Ni, Pb, and the contamination level is light pollution. But all of these6sample plots were unpolluted by Zn element. Some samples are polluted by As element, and their contamination level is light pollution. With the Heilu soil background values for the standard,6sample plots were subjected to pollution of heavy metals such as Co, Cr, Cu, Mn, Ni, Pb pollution, and the contamination level is light pollution. All are not polluted by As element. Apart from the NO.2plot with18years is not polluted by Zn elements, other samples were subjected to pollution of Zn element, and the contamination level is light pollution.