Abstract

One of the prevalent soil contaminants in Nigeria is spent engine oil (SEO). This experiment aimed to evaluate how spent engine oil affected various heavy metals and mineral composition in the rhizosphere of Arachis hypogaea L. Concentrations of 0 (control), 100, 200 and 300 ml of SEO were used to pollute soil bags containing A. hypogaea plants, respectively. In the Botanic Garden of the University of Nigeria, Nsukka, they were put up in 9 repetitions in a completely randomized manner. The soil was tested for heavy metals and mineral components after three months of contamination. In a dose-dependent manner, the data revealed a significant (P 0.05) rise in pH, organic matter, and carbon. The concentrations of lead, zinc and iron increased drastically as the concentration of SEO increased, from 0.57 in the control to 1.89 with 300 ml effluent for lead, 1.66 to 1.73 (iron) and 0.95 to 1.48 mg/kg (zinc) according to heavy metal analyses. SEO application did not negatively alter soil texture, but it did greatly improve soil cation exchange capacity, nitrogen, accessible phosphorus, and other mineral nutrients, according to the study. In conclusion, despite heavy metal deposition, the groundnut plant's rhizosphere action may have improved the mineral contents of the soil. However, more research is needed to determine the metal uptake by the plant and its potential use in phytoremediation.

Key words: Arachis hypogaea, environmental pollution; heavy metals; phytoremediation; spent engine oil.