Selenium enhanced degradation of diesel by Erigeron annuus

Abstract

Diesel leakage is a global problem and high-level contamination cannot be removed by traditional phytoremediation because rhizospheric microorganisms are inhibited at high concentrations of petroleum hydrocarbons. Hence, we look for an exogenous substance that can increase the tolerance of phytoremediation systems to high concentrations of diesel. This study assessed the effects of selenium (0.5 mg Se kg−1 soil) on Erigeron annuus exposed to various levels of diesel (0, 15, 20, 25 g kg−1) during a 60-day pot-culture experiment. Response variables included biomass, photosynthesis parameters, antioxidant enzyme activity, and the degradation rate of diesel. Concentration-dependent decreases were found in biomass, chlorophyll content, and all photosynthesis parameters exposure, except for intercellular CO2 and non-photochemical quenching, which increased. Diesel exposure induced oxidative stress, producing concentration-dependent increases in catalase (CAT) and malondialdehyde (MDA), and a decline in superoxide dismutase (SOD). Addition of Se to soil reduced the toxic response of E. annuus to diesel, attributed to Se-enhanced antioxidant activity. In addition to increasing E. annuus tolerance to diesel, Se significantly increased the removal rate; 43.7 ± 13% in Se treated soil, compared to 37 ± 10% in the control. A low concentration of Se in soil enhances the removal of diesel from soil by Erigeron annuus. This enhancement is due to increased plant tolerance toward diesel, resulting in increased E. annuus biomass and photosynthesis. Se enhances the removal of soil diesel by E. annuus and can contribute to the ongoing effort to develop an effective phytoremediation system for soils highly contaminated by diesel.