The mechanistic understanding of potential bioaccessibility of toxic heavy metals in the indigenous zinc smelting slags with multidisciplinary characterization

Abstract

Smelting slags is a well-known industrial solid waste, while there were limited studies on the key factors controlling the potential health risks caused by these smelting slags. In this work, the metal bioaccessibility in the size fractionated–zinc smelting slags was examined using various In vitro assays, in combination with multidisciplinary methods. The results indicated that the bioaccessible fractions of heavy metals showed a significant difference, but no statistical difference among different particle sizes of the zinc smelting slags. The bioaccessible metal fractions in the gastric (GP) and gastrointestinal (GIP) phases were 0 (Cr) – 91.39% (Cd)) and 0 (Cr) – 47.80% (Ni). Among the studied metals, Cd, Cu, Mn, Pb and Zn were the most bioaccessible to human. The Pearson correlation analysis showed that the carbonate bound phases of heavy metals were responsible for their bioaccessibility in GP and GIP. Moreover, the combined results of multidisciplinary characterization also further implied that the solubility behaviors of toxic elements in the smelting slags were dominated by soluble metal bearing– mineral phases and absorbable Fe, Mn and Al–rich minerals and metal bearing–precipitates during SBRC extractions. Therefore, these study results provide a insight into the potential controls of metal bioaccessibility in the zinc smelting slags, which was of great significance from the aspects of their resource recycling and risk management.