Assessment of the Pollution Threat of Boreholes Located Around an Abandoned Dumpsite in Uyo Metropolis, Akwa Ibom State, Nigeria

Abstract

Aim: The study was aimed at assessing the heavy metal and microbial contamination levels of ground water located in an abandoned municipal dumpsite in Uyo metropolis. Study Design and Duration: The study was carried-out over a period of 3 months (September to November, 2017). Water samples were collected aseptically and preserved in an ice chest immediately after collection. Methodology: Water samples were collected from 4 boreholes; 3 boreholes around the Uyo abandoned dumpsite and from 1 control borehole. The collected samples were analysed for Pb, Cd, Cr and Hg using Atomic Absorbtion Spectrophotometer (AAS), while the microbial contents were analysed in microbiology laboratory according to the methods of Gerhardt. Results: The mean concentrations of Pb, Cd and Cr in the borehole water were 0.015 ± 0.011, 0.058 ± 0.067 and 0.083 ± 0.139 mg/L respectively. The Pb and Cd concentration varied significantly between the boreholes (p<0.05), while Cr varied insignificantly between the boreholes (p>0.05). The total coliform count (TCC) and yeast count (YC) varied significantly between the borehole (p<0.05), while total plate count (TPC) of bacteria varied insignificantly between the boreholes (p>0.05). Eschericha coli was not detected in the 4 borehole water samples, but TPC and TCC were observed in boreholes 2, 3, and 4. The TPC, TCC, E. coli, and YC in borehole 1 (control) were all within the Nigerian standard for drinking water quality (NSDWQ), and was deemed healthy for drinking. In general, borehole 2, 3, and 4 are unhealthy for consumption since majority of the microbial parameters and heavy metals studied were above the NSDWQ acceptable limit. Conclusion: Despite recently moving the dumpsite far from residential areas, the boreholes around the abandoned dumpsite are still contaminated and unsafe for drinking. Thorough treatment and regular monitoring of the boreholes is recommended as a strategy, to prevent outbreak of water borne diseases.