The partitioning of Sb in contaminated soils after being immobilization by Fe-based amendments is more dynamic compared to Pb

Abstract

Soils and sediments from shooting ranges can be heavily contaminated with metals and metalloids that can leach significant concentrations into the environment. To prevent trace element leaching, contaminated soils must be stabilized prior to deposition. Here, we present a geochemical study on the lability of Sb (oxyanion) and Pb (cation) in heavily contaminated shooting range soil after amendment with a Fe-rich slag in combination with either FeSO4 or an acidic contaminated organic soil. The treatment effect on leaching potential and chemical lability with time was tested in a column leaching experiment and by a diffusive gradient in thin film technology (DGT) experiment, respectively. Both treatments substantially reduced the Sb and Pb leaching, but the slag&FeSO4 was most effective. The DGT-lability of the slag&organic-soil treatment caused a 78% and 93% reduction in SbDGT and PbDGT, respectively. The slag&FeSO4 reduced the SbDGT and PbDGT by 90% and 98.5%, respectively. Application of slag&FeSO4 to the contaminated soil, increasingly immobilized Pb as time prevailed, leaving only an insignificant fraction geochemically labile. Antimony was comparably more labile with time. This outcome indicates that although the Sb leaching was effectively reduced, the Sb sorption to the amendments is weaker and that the sorbed Sb may remain geochemically labile beyond a few weeks of contact with the Fe-rich slag