Groundwater Assessment and Contaminant Migration in Fractured Shale Aquifers of Abakaliki

Abstract

Mineralization and mining activities in the Abakaliki area generate Metallic Trace Elements (MTEs) which disperses and contaminate the environment. This could have serious environmental and health effects both in the vicinity of the mines and offsite. The migration and transport of these MTEs have not been studied and could have an important role in the degradation of groundwater in the area. This study was undertaken to evaluate the levels of hydrogeological - parameters, pH, Electrical conductivity, groundwater levels in wells, and geochemical assessment of Mg, Ca, Cl , 2- SO , As, Cr, Mn, Pb, Cd, Fe, Hg, Ag, Ni, Se, Co, and Zn using atomic absorbtion spectrophotometric method. 4 Furthermore, the extent of the influence of fractures on the migration, flow direction and subsequent transport of contaminant in the fractured shales aquifers was done using geohydrological studies and field mapping. Result indicates that MTEs are transported in the saturated zone through fracture network which trends mainly in the NW – SE direction, this controls groundwater occurrence and hydrothermal mineralization in the area. The distribution of geochemical elements indicates higher concentrations in wells within the mining areas and downstream. This is be - 2- due to non connectivity of fractures; formations of water divide; and soil/ rock/ water interaction. Levels of Cl , SO , 4 As, Mn, Pb, Cd, Fe, Hg and Se in some wells are above the World Health Organization and Standard Organization of Nigeria guidelines for drinking water. No principal flow direction was indicated, but Northeasterly and Southeasterly groundwater flow vectors were observed. Conceptual models reveal predominance of recharge area in the central parts while the northern and southern parts form the discharge areas. This is useful for proper water resources and waste management planning. The hydrogeological and geochemical investigations show that the contaminants are geogenic rather than anthropogenic.

Publication Info:

Author: Obasi, P.N. ; Akakuru, O.C. , Nweke, O.M. and Okolo C.M.

Volume: 58

Issue: March

Published By: Journal of Mining and Geology Vol. 58(1) 2022. pp. 211 - 227, 2023-03-01