*1Rabiu, Halima Musa and *2Nande, Mas’ud Yusuf
*1Department of Biological Science, Faculty of Life Sciences, Bayero University Kano
*2Department of Biology, Faculty of Life Sciences, University of Maiduguri
*Corresponding author’s Email: masudnande@unimaid.edu.ng, doi.org/10.55639/607.020100133
ABSTRACT
Soil contamination from informal auto-mechanic workshop activities is an emerging urban environmental concern, as spent engine oil, lubricants, fuel residues, and metal-bearing wastes can alter soil physicochemical conditions and increase contaminant mobility, groundwater vulnerability, and human-exposure risks. This study assessed the physicochemical properties of hydrocarbon-impacted soils from selected auto-mechanic workshops in Kano Metropolis, Nigeria, and compared them with an uncontaminated control soil to evaluate workshop-related soil-quality alteration, nutrient imbalance, and metal enrichment. Soil samples were collected from three auto-mechanic workshops and one non-oil-contaminated control site. Particle-size distribution, pH, nitrogen, exchangeable cations, and exchangeable acidity were determined using conventional soil analytical procedures, while effective cation exchange capacity was calculated from exchangeable cations and exchangeable acidity. Electrical conductivity, organic carbon, and phosphorus were predicted from near-infrared spectra using the established CDA soil spectral library, whereas Zn, Mn, and Fe were quantified following microwave digestion using MP-AES. One-way analysis of variance was used to test significant differences among sampling locations at p ≤ 0.05, while Tukey’s pairwise comparison test was used for mean separation. The workshop soils differed clearly from the control soil. They were slightly more acidic, with pH values of 5.77–5.89 compared with 6.01 in the control. Electrical conductivity and organic carbon were higher in the workshop soils, ranging from 89.40 to 101.16 µS/cm and 1.21 to 1.23%, respectively, compared with 34.00 µS/cm and 0.38% in the control. In contrast, nitrogen, phosphorus, and potassium were lower in the workshop soils. The acid digestible (pseudo-total) concentrations of Zn, Mn, and Fe were also substantially higher in the workshop soils than in the control. The findings indicate that the sampled auto-mechanic workshop soils were characterized by chemical alteration, nutrient depletion, and relative metal enrichment compared with the control soil. The study provides site-specific baseline evidence supporting routine soil monitoring, proper waste-oil management, and improved environmental control of automobile-workshop activities.
KEYWORDS
Hydrocarbon
contaminated
soil,
Physicochemic
al properties,
Soil pollution,
Metal
enrichment.