Ecotoxicity Assessment of Four Oxidizing Agents for Remediation of BTEXs-Contaminated Soil

In this investigation, four classical chemical oxidizing agents—hydrogen peroxide (H₂O₂), Fenton reagent, sodium persulfate (Na₂S₂O₈), and potassium permanganate (KMnO₄)—were employed to remediate soils contaminated with BTEXs (benzene, toluene, ethylbenzene, and xylene). Simultaneously, ecotoxicity assays were integrated to comprehensively evaluate the consequences of the remediation efforts. The various oxidizing agents demonstrated efficient removal of BTEXs from the soil at appropriate concentrations. Post-remediation ecotoxicity evaluations indicated that H₂O₂ and KMnO₄ treatments had the least phytotoxic effects on soil. On the contrary, high doses of Fenton and Na₂S₂O₈ treatments significantly increased the phytotoxicity of the soil. Each of the four oxidative interventions led to a reduced survival rate among earthworms, with a particularly pronounced effect observed at high concentrations of Na₂S₂O₈. The oxidation of water-soluble substances in the soil by Fenton and Na₂S₂O₈ exerted a significant inhibitory impact on the luminous intensity of luminescent bacteria. Conversely, the remediation with KMnO₄ substantially alleviated the aquatic biotoxicity of soil leachate. This deleterious effect was mitigated by the application of low concentrations of H₂O₂ and Fenton. However, the utilization of KMnO₄ resulted in a significant reduction in the diversity of soil microbial communities.