Distribution of Farmland Heavy Metals and Pollution Assessment in Mining Area

130 soil samples from farmlands in Weibei dry-land mining area were collected and analyzed for the content of Cd,Cr,Cu,Pb,Zn. The results indicated that the average contents of Cd,Cu,Pb were higher than those of Shaanxi Province soil background,while Cr and Zn contents were lower than those. The geostatistical analysis results suggested that the heavy metal contents decreased from west to east,and had the highest contents all around cement factory. There were significantly positive correlation among Cd,Cr,Cu,Pb and Zn. The principal component analysis was applied to estimate the sources of heavy metals. Cd in factor 1 was associated with anthropogenic activities,whereas Cr in factor 2 was mainly controlled by parent material,Cu,Pb and Zn were affected by both two factors. The quality of soils were evaluated with pollution load index( PLI) and potential ecological risk index( PER),respectively. The results show that coal mine area was clean or slightly to moderately polluted,while the cement factory area was moderately polluted. Heavy metals in soil were ranked by pollution index as Cd,Pb,Cu,Cr,Zn.