The Ecological Impact of Used Petrochemical Oils on Soil Properties with Special Reference to Physicochemical and Total Petroleum Hydrocarbon Contents of Soils around Automobile Repair Workshops

Abstract

Soils around automobile repair workshops were analyzed for physicochemical, elemental, and hydrocarbon contents with a notion to assess the contamination level of the soils via petrochemicals mishandling. The soils were collected using standard analytical procedures, while their elemental contents were determined using bulk scientific atomic absorption spectrometry/atomic emission spectrometry techniques. Total petroleum hydrocarbons, which are known to be potential carcinogens and physicochemical parameters—pH, Cl⁻, CO₃ ²⁻, electrical conductivity, and organic matter contents—were determined using standard analytical techniques. Ten elements—Mn, Zn, K, Na, Cu, Fe, Ni, Cr, V, and Pb—were analyzed and detected and their concentrations, the enrichment factors, Pollution Index, and Geoaccumulation Index values were established. The concentrations of K, Mn, V, Cr, Ni, Pb, Zn, and Cu were higher in the oil-contaminated soils than those of other Nigerian soils, while the values of the physicochemical parameters (CO₃ ²⁻, Cl⁻, and electrical conductivity) followed the same trend. The results of the Geoaccumulation Index indicated that the soils were very heavily polluted with all the metals (Geoaccumulation Index values > 5), except V (4 < I_geo < 5) which heavily polluted and Pb (2 < I_geo < 3) which moderately polluted the soils. These results were corroborated by their values, which were excessive when compared with their tolerable limits. The total petroleum hydrocarbons of the soils were detected at high levels when compared with studies of similar settings. The overall results showed that the soils of the area were highly contaminated and might be detrimental to living existence.

Keywords:

• atomic absorption spectrometry
• atomic emission spectrometry
• element
• petrochemical
• physicochemical
• soil