Effects of surfactants on rhizodegradation of oil in a contaminated soil

Abstract

The effects of nonionic surfactants on degradation of engine oil in metal contaminated soil using Indian mustard (Brassica juncea) were investigated. Triton X-100 and Tween 80 were individually applied to test pots in which the soil had been earlier spiked with 500 mg kg⁻¹ of used engine oil, 500 mgkg⁻¹ of PbCl₂ and 50 mgkg⁻¹ of CdCl₂. For he application of Tween 80 to the soil, the fractions of rhizodegraded oil and the fractions of removed metals from the soil were well correlated. On the other hand, such a correlation did not exist between the fractions of rhizodegraded oil and the fractions of removed metals for the application of Triton X-100 to the soil. It was observed that Triton X-100 caused a significant decrease in basal soil respiration (BSR) which can be attributed to a reduction in microbial activity. This, in turn, resulted in a reduction of the rhizodegraded oil fraction. Tween 80 proved to be effective in the rhizodegradation of oil under aerobic conditions. Further, this surfactant seems to have the positive effect on the soil microbial population when viewed in terms of BSR.

Keywords:

• Rhizodegradation
• phytoremediation
• heavy metals
• engine oil
• surfactant
• basal soil respiration