This paper is the result of the mine environmental geological survey engineering.

Objective Xin Barag Youqi is located in hulun buir grassland, and mining activities are frequent. Understanding the sources and ecological risks of heavy metals of soil in this area is prerequisite for assessing environmental impact.

Methods We collected a total of 221 samples of ore, bed rock and soil, and tested contents of 7 elements (Cd, Cr, As, Hg, Ni, Pb and Zn). The pollution degree and distribution characteristics of heavy metals were evaluated by geoaccumulation index method and potential ecological risk index method. The sources of heavy metals in soil were determined by correlation analysis and principal component analysis.

Results It was found that the heavy metal pollution in the soil of Xin Barag Youqi is mainly mild, and Cd, Ni, As, Cr and Pb are polluted. The contaminated areas are located in Jiawula-Chagan Mining Area, Zhuan Ulanor, northwest shore of Hulun Lake and middle of the Krumlen River. Source analysis results shows that Cr、Ni and Hg are mainly from human activities, Cd, Zn and Pb are affected by both natural factors and human activities, and As is mainly from natural factors.

Conclusions In general, the ecological risk in Xin Barag Youqi is low, and Cd has the most prominent contribution to the ecological risk of the soil in this area, which should be taken seriously in soil quality monitoring.