Accelerated remediation of pesticide-contaminated soil with zerovalent iron

High pesticide concentrations in soil from spills or discharges can result in point-source contamination of ground and surface waters. Cost-effective technologies are needed for on-site treatment that meet clean-up goals and restore soil function. Remediation is particularly challenging when a mixture of pesticides is present. Zerovalent iron (Fe0) has been shown to promote reductive dechlorination and nitro group reduction of a wide range of contaminants in soil and water. We employed Fe0 for on-site treatment of soil containing >1000 mg metolachlor, >55 mg alachlor, >64 mg atrazine, >35 mg pendimethalin, and >10 mg chlorpyrifos kg−1. While concentrations were highly variable within the windrowed soil, treatment with 5% (w/w) Fe0 resulted in >60% destruction of the five pesticides within 90 d and increased to >90% when 2% (w/w) Al2(SO4)3 was added to the Fe0. GC/MS analysis confirmed dechlorination of metolachlor and alachlor during treatment. Our observations support the use of Fe0 for ex situ treatment of pesticide-contaminated soil.