Is Hydrogen Peroxide Decomposition Suitable for Remediating Gasoline-Contaminated Soils with Contrasting Properties?

Hydrogen peroxide (HP) decomposition (Fenton process) is indiscriminately used to remediate any soil polluted with organic pollutants. To assess the impact of HP on gasoline site remediation, two soils with contrasting textures and Fe contents were selected: Inceptisol (In) – high clay and total Fe; Spodosol (Sp) – low clay and total Fe (soluble Fe2+ was supplemented). Columns of undeformed soil samples were fortified with gasoline and submitted to HP remediation. Remediated soil and leachate samples were analyzed. Total gasoline reduction was lower in sandy (62%) than in clayey (85%) soil. Despite this relatively high reduction of gasoline, secondary environmental problems were significant. There was significant acidification of Sp. Hydrogen peroxide reactions reduced organic matter content (OM) on both soils: sandy Sp − 66% and clayey In − 22%. The quality of OM was also negatively impacted (humin degradation), especially in sandy Sp. Hydrogen peroxide promoted strong phytotoxicity on sandy Sp. The leachate of Sp was also negatively impacted by HP: increasing Mn and Al concentrations and severe Daphnia magna toxicity. The viability of remediation with HP of sandy soil and sediment must be carefully analyzed case by case. On the other hand, clayey and high total Fe soils and sediments that do not need the supplementation of acid Fe2+ solution can be recommended.