| The content of heavy metals As, Cd, Hg, Cr, Pb, Ni, Cu and Zn in 164 soil samples and 88 main crop samples from Yangling farmland were determined, and the accumulation of heavy metals was analyzed and evaluated by single factor index, Nemero index, geoaccumulation index and potential ecological hazards index. The spatial distribution of heavy metals was analyzed using ArcGIS software. The average contents of the above eight heavy metals in the soil samples were 15.67, 0.18, 0.08, 51.40, 27.34, 43.25, 28.08 mg·kg-1 and 79.32 mg·kg-1, respectively. Except for Hg and Cr, the average contents of all the other heavy metals exceeded the background values for Lou soil in the Guanzhong region of Shaanxi Province. The average contents of all eight heavy metals were below the soil pollution risk screening value of agricultural land. Sample exceeding rates of Cd and Cr were 10.98% and 3.05%, respectively.Other metals did not exceed control value. Potential ecological hazards indexes Eir of As, Cr, Hg, Pb, Ni, Cu and Zn in all soil samples were lower than 40, which was a slight risk. Eir values of Cd in soil samples ranged from 0.00 to 49.00, and the average value was 22.76±7.60. The soil numbers for Cd in moderate potential ecological risks were 3.66%. The average values of the above\|mentioned eight heavy metals in crops were 0.016, 0.019, 0.005, 0.108, 0.033, 0.090, 4.880 mg·kg-1 and 29.272 mg·kg-1, respectively, which were lower than the national food hygiene standard limit. There was no significant difference in the content of the same metal were found in grains, vegetables, and fruits, and the heavy metal pollution index MPI of the crop was 0.11. Nemero index for eight heavy metals was 0.89,meaning a warning range. Comprehensive potential ecological risk index RI=36.5, meant a slight ecological risk. Results of the research showed that the overall farmland soil in Yangling Demonstration Zone was still at a clean and safe level and belonged to the category of land that should be prioritized for protection. |