Simultaneous mobilization of trace elements and polycyclic aromatic hydrocarbon (PAH) compounds from soil with a nonionic surfactant and [S,S]-EDDS in admixture: Metals

Abstract

This study evaluated the efficacy of soil washing with a nonionic surfactant (Brij98) in combination with a complexing reagent (ethylenediaminedisuccinic acid, [S,S]-EDDS) for the simultaneous mobilization of macro- and trace elements (MTEs) and PAH compounds from a field-contaminated soil. Soil fractionation studies indicated that an appreciable fraction of the Al, Ca, Cu, Fe and Mn was associated with the residual fraction but that much of the other trace elements (As, Cd, Cr, Ni, Pb and Zn) might be susceptible to soil washing. Ultrasonically aided mixing of the field contaminated soil with Brij98 and a sparing quantity (2mmol) of [S,S]-EDDS, simultaneously mobilized virtually all of the benzo[α]pyrene {B(a)P} and chrysene (CRY) and appreciable quantities of the trace elements (Cd, Cr, Mn, Ni, Pb, Zn) burdens. The recovery of both PAHs and trace elements were increased from the soil organic matter (SOM)-rich soil. This report concerns the fate of MTEs during soil washing. Multiple ultra-sonically aided washes (five or nine) with the same dosage of reagents mobilized virtually all of PAHs and decreased the levels of Cd, Cr, Ni, Pb and Zn to comply with recommended maxima. By contrast, the levels of As and Cu remained excessive after the treatments.