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ABSTRACT
Water is an essential resource for human activities such as drinking, irrigation and other activities. The physical, biological and chemical characteristics of water are necessary to ensure its sustainability. Beneku community located in Ndokwa East Local Government Area of Delta State, Nigeria plays host to a functional crude-oil drilling facility. This study was aimed at assessing the physicochemical and bacteriological properties of the Ase River and selected boreholes in the community. Beneku lies between Latitude 5ْ40ْN and 5ْ50ْN and Longitudes 6ْ15ْE and 6ْ30ْE. Three sampling sites were mapped out each from the river and borehole. River sampling sites were points A, B, C which represents the upstream, midstream and downstream portions which were 250 m apart. Borehole sampling sites were; A (sited close to the oil drilling site); B (within the community) and C (at the outskirts of the community). Triplicate samples were collected aseptically, labelled and transported immediately to the laboratory in an ice-packed box for experimental analysis. Physicochemical and bacteriological properties were examined using standard analytical microbiological techniques. The antibiotic sensitivity tests were done using the Kirby-Bauer disc method. The phenotypic virulence properties were evaluated using cultural methods. The results of the physicochemical properties of the Ase river revealed that the pH ranged from 6.11±0.02 - 6.47±0.10; total suspended solids (TSS) was 1.00±0.00 across all points; turbidity ranged from 3.00±0.00 - 3.63±0.18 (NTU); biological oxygen demand (BOD) ranged from 1.06±0.28 - 1.17±0.04 (mg/l) and electrical conductivity (EC) ranged from 4435.00±148.49 - 5810.00±650.54 (µS/cm). The physicochemical results of the borehole water samples revealed that pH values ranged from 6.40±1.12 - 6.75±0.78); EC ranged from 1894.00±214.00 - 4960±423.00 (µS/cm) and turbidity was 0.00±0.00 (NTU) across all points. The total hydrocarbon content of the river ranged from 0.24±0.02 – 0.32±0.04 (mg/l); and borehole values were insignificant across all points. The heavy metal contents of the river water showed that Pb, Zn, and Cu were found to be within FEPA limit while the values for Fe were above permissible limit. The Pb concentrations for borehole water were below detectable limits (BDL) for all sampling months. Copper (Cu) and Iron (Fe) were found in trace amounts in the borehole water. The total heterotrophic bacterial counts of the river water ranged from 61.50±3.54 - 250.00±14.14 (cfu/100ml). Borehole water had THBC range of 132.00±30.02 - 237.16±15.94 (cfu/100ml). Total coliform counts ranged from 31.50±2.12 cfu/100ml - 115.50±7.78 cfu/100ml (River). 79.17±14.85 cfu/100ml - 99.00±8.72 cfu/100ml (Borehole). The hydrocarbon utilizing bacterial counts ranged from 34.00±5.00 cfu/100ml - 140.00±10.00 cfu/100ml (River) and 36.67±7.64 cfu/ml - 56.67±5.17 cfu/ml (Borehole). Phenotypically and molecularly, the bacteria isolated and identified were: Bacillus subtillis, Pseudomonas aeruginosa, Escherichia coli, Enterobacter cloacae and Enterobacter aerogenes. The antibiotic susceptibility test revealed that all isolates were sensitive to gentamicin and ciprofloxacin, while resistance were observed for metronidazole and colistin with Bacillus subtilis showing greatest resistance. All bacterial isolates were observed to possess at least one of the phenotypic virulence properties evaluated in the study. The findings in this experiment revealed that the physicochemical parameters were within the WHO standard range, while the bacteriological tests revealed that the river and borehole water had high heterotrophic, coliform bacterial and hence, is unsafe for consumption, which calls for stringent measures which includes primary water purification practices be put in place to guarantee safe drinking water sources for residents of that community.
