Mobility of metal(loid)s in roof dusts and agricultural soils surrounding a Zn smelter: Focused on the impacts of smelter-derived fugitive dusts

Abstract The mobility of Zn, Cd, Pb, Cu, and As was assessed in an atmospheric environment and soil system near a Zn smelter by performing sequential extraction as well as Pb isotopic and mineralogical analyses for fugitive and roof dusts and agricultural soils. Transmission electron microscopy observations with selected area electron diffraction patterns confirmed that micron-sized roof dusts originated from the Zn smelter. Both fugitive and roof dusts contained zincite, massicot, franklinite, anglesite, and willemite. The sequential extraction of the fugitive dust from the Zn smelter stacks showed that Zn, Cd, and Pb were predominantly bound to the exchangeable (FI), carbonate (FII), and reducible (FIII) fractions, whereas Cu and As were significantly associated with the residual (FV) fraction and had low mobility. The estimation of remobilized concentrations of Zn, Cd, and Pb bound to labile fractions (FI and FII) in the fugitive dust implied their severe environmental and human health risks. In contrast, the studied metal(loid)s in the roof dust had low mobility except for Pb, implying the insignificant risks of roof dusts, although anthropogenic dusts from the Zn smelter significantly impacted FV as well as the non-residual fractions based on the Pb isotopic compositions of geochemical fractions. Similarly, the mobility and bioavailability of the studied metal(loid)s were low in agricultural soils, except for Cd, suggesting a low adverse effect on crops cultivated in the soil. The decrease in labile Cd fractions with depth indicated that the agricultural soil did not retain anthropogenic Cd in the soil subsurface. The mineralogical investigation combined with sequential extraction revealed that the different mobility of Zn, Cd, and Pb between fugitive dusts, roof dusts and agricultural soils resulted from the different solubility of metal-bearing minerals, e.g., zincite, willemite, simonkolleite which were not detected in the residuals of the fugitive dust collected after FIII extraction.