This paper is the result of ecological geological survey engineering.

Objective In order to find out the pollution status of two heavy metals vanadium and cobalt in the surface soil (0- 20 cm) in Tongbai- Biyang area, 5521 topsoil samples were collected to analyze and determine the content of heavy metals V and Co.

Methods The distribution characteristics, ecological risk, health risk and influencing factors of V and Co in soil were studied by using the single-factor index method, geoaccumulation index method and human health risk assessment method.

Results The results show that the V and Co in the study area were distributed in patches, and the area with high V and Co content was mainly in the south of the area. By assessing the single-factor pollution index and the geo-accumulation index, we found that there were more Co samples than V ones, and some samples had both elements. The human health risk assessment results show that adults are at a higher risk than children. The non-carcinogenic risk index of all V samples for adults was more than 1, while 99.06% of that for children was more than 1. The main route of non-carcinogenic risk transmission was through respiratory inhalation. 32.95% of Co samples for adults were deemed not acceptable regarding non- carcinogenic risk, while the figure for children was 19.74%. The carcinogenic risk indexes for both adults and children were within acceptable ranges. And the southern part of the area presented high non-carcinogenic and carcinogenic risk indexes for adults and children.

Conclusions The content of V and Co in soil was affected by not only soil clay, pH value as well as iron and manganese oxides, but also human activities. Mining in the study area may be the main cause of V and Co soil pollution and health risks.