Selenium enhanced phytoremediation of diesel contaminated soil by Alternanthera philoxeroides

Using a 60-day pot culture experiment, we investigated the effect of selenium on phytoremediation of soil containing high-level diesel by Alternanthera philoxeroides (alligator weed). Diesel (20 g kg^-1) decreased the growth of A. philoxeroides and induced oxidative stress, as indicated by tissue levels of hydrogen peroxide (H₂O₂) and malondialdehyde (MDA). Adding Se (0.5 or 1.5 mg kg^-1) to diesel-treated soil alleviated oxidative stress and improved biomass production, and the low dose was as effective as the high dose. After 60 days, the reduction in rhizospheric soil diesel was 20.1 ± 0.55% without Se and 35.2 ± 3.6% with Se, showing a significant increase in efficiency. Again, the low Se dose was as effective as the high dose. These findings advance the field phytoremediation by demonstrating that Se, at 0.5 mg kg^-1, enhances removal and increases plant tolerance to petroleum hydrocarbons.