Assessment of Heavy Metal Status of Boreholes in Calabar South Local Government Area, Cross River State, Nigeria

Although, many heavy metals are necessary in small amounts for the normal development of the biological cycles, most of them become toxic at high concentrations. The major sources of heavy metal pollution in urban areas of Nigeria are anthropogenic, while contamination from natural sources predominates in the rural areas. The study examined heavy metal status of boreholes in Calabar South, Cross River of Nigeria. Four functional boreholes in the area were sampled. Result showed that the concentrations of iron (Fe), zinc (Zn) and Manganese (Mn) were within WHO maximum permissible limit with mean values of 0.065ml-1g, 0.015mgl-1 and 0.002mgl-1 respectively. The proportion of copper (Cu), chromium (Cr) and lead (Pb) in the sampled boreholes was zero, indicating the absence of these metals in the sampled boreholes. The absolutely low levels of heavy metal contents across the sampled boreholes showed they were not polluted and as such suitable for human consumption. The low content also revealed that boreholes in the area were located far away from dumpsites; soak away pits, automobile shops and other forms of heavy metal contaminants. In order to maintain quality status of boreholes in the area, routine monitoring and assessment of boreholes mostly the indiscriminate sinking of boreholes in the area by sanitary inspection officers was suggested.