Evaluation on Heavy Metal Pollution of Cropland Soils in the Upstream of the Bi River Using GIS

Taking the crop lands around Xinjing village in the upstream reaches of the Bi River as study area, this paper measured the contents of four heavy metals (Pb, Zn, Cd and As), evaluated the pollution degree using the pollution index and interpolated their spatial distribution by Kriging method in ArcGIS. The results indicated: (1) only the content of Cd exceeded background levels of soils, which was 9.53 times as GradeIIof GB15618. There is obvious spatial difference among heavy metals and the main contamination sources may be were external inputs. The frequency distribution and distribution the corresponding curves of the four kinds of heavy metals were not a normally distribution. (2) There are higher accumulations of heavy metals such as Cd, Pb, Zn and As in cropland soils. On the basis of the value of Integrated Pollution Index (PIN), was 7.01 which showed the degree of the heavy metal contamination the severe pollution in study area. Cd was the major one and severe pollution, which value of Single-factor Index (Pi) was 9.53; while the other heavy metals three were no pollution. (3) The content of heavy metals had differences in elevation. The riverside sample transect was polluted seriously, while the hill one was affected lightly. The content of heavy metals had the same trends but differed in kinds of heavy metals.