Reduction of soil contamination by cypermethrin residues using phytoremediation with Plantago major and some surfactants

BackgroundSurfactant-enhanced phytoremediation is an eco-friendly treatment for reducing soil contamination. Cypermethrin (CYP) is one of the most widely used pyrethroid insecticides against different pests, and its use causes soil contamination. The aim of this study was to investigate the removal of CYP from contaminated soil by Plantago major (PM) and some surfactants. For the first time, we documented the uptake and translocation of CYP from the soil and used some strategies to improve the effectiveness of this technology, which involved the use of various surfactants to solubilize the contaminant. In a pot experiment, four surfactants [liquid silicon dioxide (SiO2, 750mgL(-1)), 2-hydroxypropyl-beta-cyclodextrin (HP ss CD, 1%), humic acid (HA, 10mgL(-1)) and Tween 80 (Tw80, 9.2mgL(-1))] were used to facilitate the phytoremediation of CYP (10 mu gg(-1))-contaminated soil by PM.ResultsOur data showed that amending the soil with PM plus SiO2 significantly reduced the amount of CYP in the soil and highly increased the concentrations of CYP in the plant roots and leaves. The longest half-life value (t(1/2)) of CYP was in the sterilized soil treatment (24.8days), and the shortest was in the soil with PM amended with SiO2 (6.41days). The half-life value (t(1/2)) of CYP in soil with PM alone was 10.0days. Through in vitro experiments, a batch equilibrium technique showed that hydroxypropyl-ss-cyclodextrin (HP ss CD) is the best surfactant to most efficiently eliminate CYP from the soil. However, in the greenhouse experiment, the addition of SiO2 to soil cultivated with PM was more effective than the use of other solubility-enhancing surfactants in the removal of significant amounts of CYP (p>0.05) from the contaminated soil.ConclusionsThe integration of SiO2+PM is the best treatment and is recommended for minimizing plant contaminant contents in CYP-contaminated soil.