Bioavailability and mobility of trace metals in phosphogypsum from Aqaba and Eshidiya, Jordan

Abstract

As, Cd, Cr, Cu, U, and Zn in Aqaba and Eshidiya phosphogypsum showed relative uniformity in particle size presented by coarse (>0.212 mm); medium (0.212–0.053 mm); and fine (<0.053 mm) in the stacks by age of deposition. Jordan phosphogypsum contains low concentrations of As, Cd, Cr, Cu, U, and Zn compared to those reported worldwide. The bioavailability and mobility of trace metals were estimated using aqua regia leaching experiments. Leaching results have shown that around 3% of the As, 1% of the Cd, 5% of the Cr, 9% of the Cu, 4% of the U, and 3% of the Zn are transferred to the surrounding aquatic environment and/or soils. Mobility of trace metals in phosphogypsum was classified into three degrees: elements with high mobility were Cu and U; those with moderate mobility were As and Zn; and those with low mobility were Cd and Cr. It can be concluded that As, Cd, Cr, Cu, U, and Zn were not only uniformly distributed in the stack, but they are not leached from the phosphogypsum stacks in any significant amount, and then they are not easily transferred to the surrounding aquatic environment and/or soils.