ENVIRONMENTAL CAPACITY OF HEAVY METALS IN FARMLAND SOILS IN YANQI BASIN, XINJIANG

For the further understanding of soil environmental capacity, a total of 191 farmland soil samples were collected from Yanqi Basin, and the concentrations of seven heavy metals (As, Cd, Cr, Cu, Ni, Pb and Zn) were identified. The characteristics and spatial distribution of heavy metal environmental capacity of farmland soils were analyzed based on GIS technology and the comprehensive capacity index. Results showed that: 1) the average concentrations of As, Cd, Cr, Cu, Ni, Pb and Zn in farmland soils in Yanqi Basin was under the limits of the risk values of National Standard of Agricultural Land Contamination (GB 15618—2018); 2) the average values of single environmental capacity index of heavy metals in farmland soils were ranked as: As > Cr > Ni > Cu > Pb > Cd > Zn. The environmental capacity of As was classified into the high capacity level, while Ni, Cr, Cu, Pb, Cd, and Zn into the medium capacity level; 3) the spatial distribution patterns of environmental capacity of seven heavy metals were different. The proportion of areas with different capacity was ranked as: medium capacity area > high capacity area > low capacity area > super capacity area > warning capacity area. Results of this study will provide scientific basis for protection and management of agricultural soil environmental quality in similar area.