Effect of thermal treatment based on SSP5-8.5 climate scenario on the leachability of toxic metallic elements from amended mine soils

In situ stabilization methods using chemical amendments are widely applied to reduce the mobility of toxic metallic elements in abandoned mine soils. However, the long-term stability of amended soils under climate change–induced thermal stress remains uncertain. This study evaluated the effects of elevated temperature on the leaching behavior and stabilization efficiency of metallic elements in amendment-treated mine soils. Two mine soils were amended with limestone (LS) and steel slag (SS) and subjected to thermal aging at 90 °C for eight weeks, simulating accelerated weathering under the SSP5–8.5 climate scenario. Sequential extraction and batch leaching experiments were conducted to assess physicochemical transformations and the mobility of metallic elements. Thermal aging significantly increased the initial and cumulative leaching of Cu, Zn, As, and Cd compared with ambient conditions. Regression analysis identified Al and Fe as key geochemical regulators of metal mobilization under high-temperature stress, with Al hydrolysis–induced acidification enhancing the solubility of cationic elements and reductive dissolution of Fe oxides promoting As release. Although LS and SS treatments consistently reduced the leachability relative to unamended controls, elevated temperature partially weakened their stabilization efficiency. These findings demonstrate that climate-driven thermal stress can induce secondary mobilization of metallic elements through Al- and Fe-mediated processes, highlighting the need to assess the long-term durability of soil amendment–based remediation strategies under future extreme climate conditions.