Effect of Aging and Wet-Dry Cycles on the Elimination of the Bioavailable Fractions of Cu and Zn in Contaminated Soils by Zero Valent Iron and Magnetic Separation Technique

Abstract

Anthropogenic activities are continually transforming the Earth’s surface and resulting in significant disturbances of ecosystem services including those provided by soil resources. However, advances in chemical, biological, and material sciences make it possible to develop both preventive and corrective solutions to soil pollution problems. Here we present the results of preliminary studies on the elimination of the bioavailable fraction of copper (Cu) and zinc (Zn) from contaminated soils, by taking advantage of enhanced corrosion of zero-valent iron (ZVI) particles and their strong magnetic characteristics to retrieve the formed heavy metal-ZVI complexes from treated soils. The 48-h Ceriodaphnia dubia acute toxicity assay and MetPLATE were used to assess the ability of the tested remediation approach to eliminate Cu and Zn toxicity as a function of soil types and contact time between metals and soils, with or without wet-dry cycles. In sandy soils, the toxicity associated with the water extractable Cu and Zn decreased by two orders of magnitude after treatment. In organic-rich soils, differences in the affinity of Cu and Zn for soil organic matter drove the observed toxicity removal trends, with Cu toxicity mitigation linked primarily to its high affinity for soil organic matter. Trends of the removal of Zn toxicity in organic-rich soil mimicked those observed in sandy soil, but with the removed toxicity units varying just within one order of magnitude.