Contents and Its Characters of Heavy Metals with Tobacco-Growing Soils in Zhengan County of Remote Karst Agricultural Area

The 66 representative samples with tobacco-growing soils was collected in typical tobacco-producing county in Karst remote agricultural areas in order to study the contents and characteristics of heavy metals with tobacco-growing soils under county scale.The results showed that all the contents of Pb,Hg and Cr accorded with Grade Ⅱ,National Soil Environmental Standard,the sample numbers of As content which accorded with the Grade Ⅱ accounted for 98.5% of the total.The standard of the four metals contents was less than polluted standard.The sample numbers of Cd content,which accorded with the Grade Ⅱaccounted for 69.7%,and the numbers more than the Grade Ⅲ,National Soil Environmental Standard accounting for 10.1%,and so the part of tobacco-growing soils was polluted by Cd.The difference between contents of heavy metals with 3 different types of tobacco growing soils was bigger,the lime soil was the highest in the mean contents of Cd,Hg,As with 0.51 mg/kg,0.173 mg/kg,15.45 mg/kg respectively,and the paddy soil highest in the mean contents of Pb,Cr with 66.13 mg/kg,55.63 mg/kg respectively,and the yellow soils was in the middle in the metal.The contents of heavy metals with tobacco-growing soils was closely correlated with soil texture and soil particle diameter.The clay had positively significant correlation with Cd,As,Hg(r=0.333**,r=0.345**,r=0.289*), and the sand had negatively significant correlation with Hg,As(r=-0.286*,r=-0.245*).The environmental condition of heavy metals with tobacco-growing soils in remote Karst agricultural area was sound,but the control and management of Cd should be emphasized.