The environmental and geochemical studies at Enyigba Pb-Zn mining district near Abakaliki South eastern Nigeria were undertaken to characterize the distribution of mobile heavy metals in rocks. A total of twenty-one (21) samples were collected from rock samples in the area. The distribution and determination of total concentration were estimated. The geochemical studies include sampling, partial leach test and chemical analysis for As, Cd, Ca, Co, Cu, Mn, Ni, Pb and Zn using UV-Spectrophotometer. The result revealed high concentration of some of the metals in the sampled media with decreasing concentrations with distance from known Pb/Zn mining sites for mostly Cd, Pb, As, and Ni. Their potential distribution and environmental risk were evaluated using enrichment and contamination factor. Indices of geoaccumulation, contamination and metal enrichment showed generally high values for Cd, As, Pb and Cu. compared with permissible limits and standard. Generally the concentration is in order: Cd > Pb > Cu > As > Co > Zn > Zn; for rock samples. Compared to permissible limits, the degree of enrichment is very high for Cd and moderate for Pb, and Cu in the rocks samples. Also the calculated contamination factor shows low to very high contamination status. 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 soil and water sources.

Hydrogeochemical evaluation of groundwater quality of Abakaliki and its environs was carried out on a scale of 1:25,000. The concentrations of selected metals in 25 groundwater samples namely Fe, Pb Zn, Cu, Mn, Co, Ni, Ba, Ag and Cd were determined using Atomic Absorption/emission Spectrophotometer (AAS) 205model. The pH of the sample were determined using a handheld digital pH meter 350 model. The pH values ranged from 6.1-7.0 indicating that the samples are slightly neutral. Analysis for physico-chemical parameters and variables (ANOVA) was done using standard methods. StatistiXL 1.5 was used for performing the grouping. Chemical analysis and various concentrations of the heavy metal loads show that the groundwater has little or no trace of Fe (0.01mg/l) Cu (0.03mg/l) Zn (0.02mg/l) Pb (0.01mg/l) and Co (0.02mg/l) contamination. The concentrations of Fe (0.03 mg/l) Pb (0.01 mg/l),Co(0.03mg/l) and Zn (0.02mg/l) were in compliance with WHO (2011) permissible standard for drinking water while the concentration of Cd ranged from 0.11mg/l to 0.14mg/l and silver 0.06 mg/l to 0.08 mg/l are far above World Health Organisation standards indicating that the area are moderately contaminated with Cd and Ag. The hydrogeochemical analysis carried out during this study stands as a guide to the best sustainable management of some contaminated aquifer systems of Abakaliki and environs. Statistical analysis of variance (ANOVA) revealed that Fe, Cu and Co were significant at P<0.05. The analysis reveals that the concentration of the various heavy metal load in the study area decreases away from the source point as in areas near to the Ricemill husk/cluster.

The present study was aimed to assess the levels of heavy metals in Abakaliki and its environs, south eastern Nigeria. A total number of 15 water samples (12 boreholes and 3 hand dug wells of groundwater points) were collected from different locations of the study area and analyzed for the concentration of heavy metals: As, Cd, Cu, Ni, Pb, and Zn using Atomic Absorption Spectrophotometer of Perkin-Elmer Analyst 100 Model. The pH of the water samples were determined using Hanna digital pH meter. The result of the analysis showed that water samples from the area have pH range of 6.0-7.8 which falls within the acceptable limit of WHO, 2008 standard permissible limit for portable water. The concentration of these metals in groundwater were found in the ranges of As (nil-2.40mg/l), Cd (0.06-0.41mg/l), Cu (nil-3.10mg/l), Ni (0.08-1.15mg/l), Pb (0.10-0.90mg/l) and Zn (nil-1.35mg/l). The result also revealed that some water samples in some locations such as Hausa quarters, off Onwe road, Azu-Ebonyi, Mechanic village, Ogoja road and Building Materials contained As, Cd, Cu, Ni and Pb that exceeded permissible limit recommended by WHO standard. It also showed that the distribution of these metals was found in both the two sources of waters sampled (borehole and hand dug well) in the area. The reason for these heavy metals in groundwater could be as a result of hydrochemical activities within the rock formations that bear the groundwater in the area. As a result, adequate hydro geological studies should be carried out when locating boreholes in the area for health reasons and domestic use.