Geochemical assessment of the distribution of mobile forms of heavy metals in oil-contaminated alluvial soils of the middle taiga subzone of Western Siberia

The article considers the content of mobile forms of heavy metals (HM) in oil-contaminated soils of the middle taiga subzone of Western Siberia. The studies were conducted for the upper soil horizons (0–20 cm) in various zones of anthropogenic impact (epicenter, impact zone, zone boundary) and in the background areas. The analysis results showed a significant excess of HM concentrations over the maximum permissible values (MPC) established by SanPiN 1.2.3685–21, as well as over background levels in oil-contaminated soils. The content of mobile forms of HM in the anthropogenic impact zone decreases in the following order: V > Mn > Ni > Cu > Pb > Zn. In the course of the work, correlations between the content of mobile forms of HM, organic carbon (Corg) and petroleum products (PP) were calculated, and the geo-accumulation coefficient (Igeo) and the total index of soil pollution (Zc) were determined. It was established that Zc values decrease naturally with distance from the pollution epicenter. All the studied zones are in the pollution range that requires monitoring and measures to reduce the anthropogenic impact. The elements Zn, Mn and V demonstrate consistently high Igeo and Zc values, which is associated with their increased technological activity. The revealed patterns emphasize the need to develop and implement comprehensive environmental protection measures to restore the ecological state of contaminated soils.