Heavy Metal Contamination and Vegetation Restoration Evaluation System in Mining Areas for Sustainable Ecosystem Management

Mining activities in arid and semi-arid regions have inflicted severe damage on the fragile grassland ecosystems. Undrained waste dumps in these areas are often covered with both prairie vegetation and substantial quantities of mining waste. Wind and rainfall further exacerbate the degradation of surrounding grasslands, intensifying soil erosion and deteriorating the ecological environment of coal mining zones. This issue has become a critical constraint on the sustainable development of the regional economy. Therefore, analyzing the characteristics of soil heavy metal pollution and establishing risk assessment indicators for vegetation ecological restoration in mining areas can provide a scientific basis for heavy metal pollution control, thereby promoting the sound and rapid development of the national economy. The analysis of heavy metal pollution characteristics in the mining area reveals that all heavy metal elements except lead (Pb) exhibited mild pollution; in particular, copper (Cu) pollution was widespread. Manganese (Mn) and zinc (Zn) pollution was generally concentrated within a 5[Formula: see text]km radius of the mining area, presenting as mild pollution. Additionally, mild Zn pollution was also detected in the northeastern region 4–8[Formula: see text]km away from the mining area. Comprehensive pollution index evaluation results indicate that mild heavy metal pollution in the mining area —except in the eastern and northeastern parts — primarily occurs within a 2[Formula: see text]km radius of the mine. Cluster analysis and principal component analysis yielded consistent results, indicating that chromium (Cr), copper (Cu), manganese (Mn), zinc (Zn) and lead (Pb) originated from identical sources. Risk assessment index analysis of the organic restoration target system confirms the effectiveness of artificial vegetation restoration technology. Vegetation can increase soil organic matter, alkali-hydrolyzable nitrogen and available phosphorus contents. Moreover, phytoremediation measures can significantly reduce soil heavy metal content (except for Pb), and the heavy metal content in soil after vegetation restoration can reach the level equivalent to that in the 10[Formula: see text]km buffer zone around the mining area.