Chemical and Mineralogical Evidence for Solubility and Mobility of Lead from Lead Mine-Affected Soils to Aqueous Environments

Abstract

The mobility of Pb binding in mine-affected soils to aqueous environments was studied using a combination of chemical and mineralogical methods. Leaching test was supplemented by mineralogical investigation of both soil samples and Pb mineral fractions using X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM). The level of Pb determined by ICP-MS showed maximum concentration of 2.550 ppm and 3225 mg/kg Pb, which is far higher than the World Health Organization (WHO) and Soil Guidelines Value (SGV) for water and soil, respectively. Thus, the leachability of Pb in the area established. Concomitantly, the potential release of Pb into the environment was further revealed by SEM XRD for mineralogical analysis of Pb forms and soil components. The results showed that Anglesite among the five lead-bearing phases observed was the most abundant pool of soil Pb and most soluble fraction. Thus, the geochemical partitioning, potential mobility and bioavailability of soil-associated Pb are established, which perhaps accounted for the transportation of Pb to nearby river water. However, XRD showed high proportion of quartz (81%), aluminosilicates (14%) and traces of feldspars, of which aluminosilicates perhaps cause the retention of some forms of Pb in the area.