SEASONAL VARIATION IN HEAVY METAL COMPOSITIONAL PROPERTIES OF GROUNDWATER RESERVOIRS IN AKWA-IBOM STATE OF NIGERIA FOR QUALITY EVALUATION

This work paints a ‘broad brush’ picture of the water quality of groundwater reservoirs with respect to heavy metals compositional properties before observable changes in the seasons of dry and wet periods. Thus, the underground water variation status of Akwa Ibom State of Nigeria, in West Africa, was evaluated with respect to heavy metal composition in its reservoirs, for consumptive safety validation. A total of 108 water samples were collected from the reservoirs through bore holes at nine research locations (three zones of three sub locations with twelve units), during two major periods of dry and wet seasons. These were analytically used to examine the existence levels of heavy metals of iron (Fe), zinc (Zn), manganese (Mn), cadmium (Cd), lead (Pb), copper (Cu), and chromium (Cr) in the water samples from the underground reservoirs of the studied area. The results were compared with the regulatory monitory water standard for quality evaluation. It was found that most of the heavy metals were within Nigerian Standard for Drinking Water Quality (NSDWQ) and World Health Organization (WHO) water safety limits. And, the variations were: Fe (-0.04 to 0.28), Zn (0.11 to 0.27), Mn (0.02 to 0.11), Cd (0.007 to 0.04), Pb (-0.11 to - 0.09), Cu (-1.92 to 0.05), and Cr (0.21 to 2.68). Treatment for improvement was recommended based on the findings.