Assessment of Contamination of Underground Water Sources in Enyigba Pb-Zn District, South Eastern Nigeria using Metal Enrichment and Pollution Indices

Author(s): Paulinus N. Nnabo

Samples were collected from four (4) underground water sources in Enyigba Pb-Zn mining district, near Abakaliki in southeastern Nigeria. The samples were acidified to stabilize the metals for periods more than four days without the use of refrigeration. The acidified water samples were analysed by a commercial laboratory at Projects Development Institute (PRODA), Enugu using Atomic Absorption Spectroscopy (AAS). The elements determined by this method are lead (Pb), zinc (Zn), copper (Cu), arsenic (As), cadmium (Cd), nickel (Ni), manganese (Mn) and cobalt (Co). The result and analysis showed that metal enrichment index (MPI) of As, Cd, Pb and Ni are very high in the groundwater samples, indicating high degree of contamination compared to WHO permissible limits. All these metals contributed to high degree of contamination based on metal pollution index (MPI). The calculated metal enrichment and pollution indices show values that indicate that under the prevailing conditions and environmental regulations in Nigeria, the Enyigba mining district would face major and hazardous discharges of these metals to other water sources in the area.

Metal Enrichment Index, Metal Pollution Index, Underground Water, Lead/Zinc Mines, Enyigba

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