Ekwere, A. S. and Edet, A.
Concentration levels of selected potentially toxic trace elements (Fe, Mn, Pb, Ni, Cd, Cr) were determined for surface waters and ground waters of deep and shallow aquifers within the Precambrian basement of Oban massif (south-eastern Nigeria). The aim of this was to determine the source of the elements and assess indications of possible pollution. Statistical analysis (mean, range and standard deviation) indicates no significant variations across sampling seasons and concentration levels are within common ranges. Correlations, factor analysis and metal load classification indicates geogenic processes of weathering and leaching of basement rocks as major source of these elements.