Pollution, fractionation and potential risks of V and Cd in soils from stone coal mines in Heshan region, Yiyang City

This study investigates the mineral and soil characteristics of stone coal mine in southern China, focusing on metal pollution, chemical fractions, and associated risks. The research highlights significant enrichment of vanadium (V) and cadmium (Cd) in the stone coal. V is predominantly found in aluminosilicate minerals (83.7%), while Cd is exclusively associated with sulfide minerals (100%). In comparison to contaminated site soil, the form of V in paddy soil may change due to alternating dry and wet farming conditions, resulting in an increased proportion of reducible and oxidizing states. Additionally, Cd is released through sulfide weathering and migrates to deeper soils via acidic weathering solutions, posing high biological toxicity and mobility. Principal Component Analysis indicates that metal accumulation in the mining area is closely linked to natural geological factors, mining activities, and agricultural practices. The Geo-Accumulation Index (I_geo) and high hazard quotients (HQ) demonstrate severe cadmium pollution in the NB mine area (I_geo = 4.75) and potential non-carcinogenic risks from V for children (HQ > 1). These findings are crucial for ecological restoration efforts, promoting sustainable agricultural practices, and enhancing public health in areas impacted by mining activities.