Assessment Of Heavy Metal Contamination Of Water Sources From Enyigba Pb-Zn District South Eastern Nigeria

Abstract A total of thirty 30 water samples were collected from the Enyigba PbZn mining district to assess the contamination of the water sources as a result of mining of lead and zinc minerals in the area. This comprises of 12 samples of surface water 14 from mine ponds and 4 from underground borehole water. 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 of contamination factor showed that in surface water Cd had the highest concentration followed by As and Pb while Ni had the lowest. In mine ponds Cd also had the highest concentration and followed by Pb and As and Ni the lowest. In borehole water Cd has the highest concentration followed by Pb and As while Ni had the lowest concentration. Compared to WHO permissible limits the contamination of the heavy metals in all water sources are in order CdAsPbNiZnCu. In surface water the order is CdAsPbNiZnCu in mine ponds it is CdPbAsNiZnCu and in borehole water the order is CdAsPbZnNiCu. The calculated contamination factors show very high contamination status for Cd Pb and As. These levels of contamination and values indicate that under the prevailing conditions and environmental regulations in Nigeria the mining district would face major and hazardous discharges of these metals to the water sources.