Abstract:Aimed to reveal the distribution characteristics of different land use types, six land use types were chosen, including citrus orchard (CO), forest land (FL), wheat dry land (WD), vegetable dry land (VD), vegetable greenhouse land (VG) and paddy land (PL) as the research objectives in the typical watershed in Three Gorges Reservoir region. The contents and distribution characteristics and pollution evaluation were all analyzed, the results showed that the order of Pb contents changed from high to low were VG, CO, PL, VD, FL and WD, the Cr contents changed from high to low were CO, VG, PL, VD, FL and WD, the Cu contents changed from high to low were VG, VD, CO, PL, FL and WD, the Zn contents changed from high to low were CO, VG, PL, WD, VD and FL and the Cd contents changed from high to low were VG, CO, WD, PL, VD and FL. Meanwhile, there existed obviously positive correlation between Pb content and Cr, Cu, Zn and Cd contents（p<0.01）, there also existed obviously positive correlation between Cr content and Cu, Cd contents（p<0.01）and there existed positive correlation between Cr content and Zn content（p<0.05）. The estimation of single pollution index of these five soil heavy metals, i.e., Pb, Cr, Cu, Zn, Cd contents of the six land use types changed from high to low were 0.06, 0.14, 0.15, 0.14 and 1.70. And the comprehensive pollution index was 0.91, the pollution degree belonged to guard line and the pollution level was the Ⅱ level—relative clean. Meanwhile, the order of the six land use type of soil heavy metals changed from high to low were VG, CO, VD, PL, WD and FL. The results of the potential ecological risk index indicated that the soil heavy metals Pb, Cr, Cu and Zn belonged to light ecological risk. However, the soil heavy metal of Cd belonged to middle ecological risk in the forest land, dry land of wheat and paddy land, Cd belonged to a bit strong ecological risk in the citrus orchard, vegetable dry land and vegetable greenhouse land. And the potential ecological risk index of these five soil heavy metals changed from high to low were Cd, Pb, Cu, Cr and Zn.
