This paper is the result of environmental geolgical survey engineering.

Objective Inner Mongolia is abundant in mineral resources, however, mining activities are also accompanied by adverse effects on groundwater environment. Investigating the hydrogeochemical component characteristics, sources and potential health risks to humans of the mine pit-groundwater system of an iron mine has significant practical importance and scientific value.

Methods The hydrochemical origin of groundwater in the mining area were explored by means of Gibbs diagrams and ion proportion analysis. The distribution characteristics and sources of heavy metals in groundwater were investigated by multiple statistical methods, such as correlation analysis and principal component analysis.The distribution characteristics and sources of heavy metals in groundwater were investigated by multiple statistical methods, such as correlation analysis and principal component analysis. Additionally, the human health risk assessment of mine groundwater was carried out.

Results The groundwater in the study area mainly evolved from Ca-SO₄ type to Ca-HCO₃ type from mine to dry river. Shallow groundwater components are mainly controlled by water rock interaction, while evaporation concentration and atmospheric precipitation have little impact. The correlation analysis results show that heavy metals in the groundwater within the study area have homologous or associated relationships. The principal component analysis results indicate that the concentrations of heavy metal elements in the groundwater could be explained by two principal components. Ranked by the contribution rates, the principal components respectively represent mining activities and groundwater background value. Human health risk assessment results indicate that Fe, Ni, Pb and Al do not pose any health risk to local residents through ingestion of groundwater.

Conclusion The primary heavy metal pollutants in groundwater are Fe, Ni, Al and Pb. Although the current concentrations of these metals in groundwater are low, the results have shown an increasing trend from a distance to proximity to the mine, indicating that these metals have dispersed into the shallow groundwater surrounding the mine. It is recommended that the groundwater environmental quality should be monitored regularly during future mining activities.