Pollution indices and microbiological assessment of soil samples from motor parks around New Benin Market, Benin City, Nigeria

Abstract

This study was designed to assess the physicochemical, pollution level and microbiological quality of soil samples collected from motor parks around the busy New Benin Market. Four different motor parks were selected for the study including a control location. Atomic Absorbance Spectrophotometry, pour plate method were adopted in analyzing the physico-chemical, heavy metals and microbial flora of the top soils Result obtained for physiochemical analysis revealed pH and electrical conductivity of the soils ranged from 6.68±0.09 - 7.39±0.12 and 314.5±34.50 – 1598.5±157.50μS/cm respectively. Soil particle analysis revealed percentage composition of sand and silt ranged from 92.92±0.91 – 95.585±0.12 %. And 2.32±0.17 – 4.33±0.05 % respectively. The levels of Lead, Cadmium and Chromium 0.01±0.01 – 0.06±0.04 mg/g, 0.02±0.02 – 0.14±0.11 mg/g and 0.02±0.01 – 0.14±0.11 mg/g respectively. The ecological risk index in soil samples revealed that lead, cadmium and chromium concentrations in soil samples had no ecological risk (ERI<40). Pollution Load Index of soils ranged from 0.00229-0.00607. Potential ecological risk index (PERI) of soils ranged from 0.007-2.41. The Total heterotrophic bacterial counts and Total fungal counts of the soil samples ranged from 60.50±2.50 – 114.00±3.00 (×104 cfu/g) and 50.50±5.50 – 70.50±4.50 (×104 cfu/g) respectively. Identified bacteria were Klebsiella sp., E. coli, Enterobacter aerogenes, Aerobacter sp., P. mirabilis, Serratia sp., Bacillus sp. And Micrococcus sp. Predominant fungal isolates were species of Aspergillus, Trichoderma, Mucor and Penicillium. The contamination levels from the studied soil samples indicate relative low pollution; however, there is a call for environmental attention to avoid any possible escalation of pollution levels.