Geochemical characteristics of metal(loid)s in forest soil profiles affected by Pb-Zn ore mining

The lead-zinc mining activities have an impact on the metal(loid)s content in the environment within the mining area. However, the influence of these activities on the soil environment at greater distances, such as 30 km away, has received less attention. Furthermore, previous investigations often failed to take into account factors such as topography and weathering in their analyses. The present study explored the influences of lead-zinc mining on the migrations of sulfophilic metal(loid)s in soils, by analyzing geochemical characteristics of forest soil profiles from different locations on Baohua Mountain near a lead-zinc mine in the Nanjing area, China. The results show that Cd, Pb, Zn and Sb enrich in shallow soil (0-15 cm), possibly due to mining. Hillslope and foothill soils exhibit distinct elemental distribution. Slope soils has higher Pb, Cd, Sb, In, Zn, Ni, Cu, Al, Fe, K, Mg, Ti, S, and TOC contents but lower Mn and Ca contents compared to foothill soil. Ni, Cd, Fe, Al, K, Mg, Si, Ti, Na, S and TOC distributions are similar in slope and foothill profiles, while Pb, Sb, Cu, Zn, In, Mn, Ca, P, pH, Av-In and Av-Pb distributions differed obviously. Foothill soils show notable Cd, Pb, Zn and Sb leaching migration at 0-25 cm layer, with exogenous Pb migrating vertically up to 25 cm. Stronger weathering and leaching influence Pb, Zn, Sb, In and Cu migration mainly in slope soil's sub-surface layer (10-25 cm), with Cd leaching more prominent and Pb migrating farther vertically than in foothill soils.