A typical case study from smelter-contaminated soil: new insights into the environmental availability of heavy metals using an integrated mineralogy characterization.

Mineralogy was an important driver for the environmental release of heavy metals. Therefore, the present work was conducted by coupling mineral liberation analyzer (MLA) with complementary geochemical tests to evaluate the geochemical behaviors and their potential environmental risks of heavy metals in the smelter contaminated soil. MLA analysis showed that the soil contained 34.0% of quartz, 17.15% of biotite, 1.36% of metal sulfides, 19.48% of metal oxides, and 0.04% of gypsum. Moreover, As, Pb, and Zn were primarily hosted by arsenopyrite (29.29%), galena (88.41%), and limonite (24.15%), respectively. The integrated geochemical results indicated that among the studied metals, Cd, Cu, Mn, Pb, and Zn were found to be more bioavailable, bioaccessible, and mobile. Based on the combined mineralogical and geochemical results, the environmental release of smelter-driven elements such as Cd, Cu, Mn, Pb, and Zn were mainly controlled by the acidic dissolution of minerals with neutralizing potential, the reductive dissolution of Fe/Mn oxides, and the partial oxidation of metal sulfide minerals. The present study results have confirmed the great importance of mineralogy analysis and geochemical approaches to explain the contribution of smelting activities to soil pollution risks.