Abstract:
The content of heavy metal in soil of the planting bases of Polygonum multiflorum as well as single pollution index and comprehensive pollution index were analyzed and evaluated based on soil testing of the two typical planting bases of Polygonum multiflorum in Guizhou——Chinese herb planting base in Wangsi town in Duyun city and the Polygonum multiflorum planting base in Longtang village in Shuangjing town, Shibing county. The results showed the average pH of soil in Duyun Polygonum multiflorum planting base was 5.5 while that in Shibing Polygonum multiflorum planting base 6.29, the average of the two pH being 5,73. The soil of these two bases were acid. For the former base, the average value of Cu、Zn、Co、As、Cr、Cd、Pb and Hg in soil were respectively 52.82, 202.70, 10.49, 31.45, 80.80, 0.48, 64.34 and 0.39 mg/kg and the heavy metal pollution condition is Cd > Hg > Pb > As > Zn > Cr > Cu > Co while for the later base, that of Cu、Zn、Co、As、Cr、Cd、Pb and Hg respectively 13.65, 65.31, 7.08, 23.19, 61.21, 0.35, 32.37 and 0.06 mg/kg and the heavy metal pollution condition Cd > As > Pb > Cr > Zn > Co > Hg > Cu.The Nemerow pollution index for evaluating the heavy metal pollution of soil in Duyun planting base and Shibing planting base respectively are 1.41 and 0.89, showing the former base is of the mild pollution and the later one still free of pollution. Among the heavy metal pollution factors of soil in these two bases, Cu、Co and Cr don't exceed the allowed standards and Cd is the most prevalent contaminant.