Abstract

Nine surface water samples collected from springs and streams in Okhuokhuo area, southern Nigeria, were analyzed by gamma spectroscopy for natural (238U, 232Th and 40K) and man-made 137Cs radionuclides while the concentrations of 59 major, trace and rare earth elements were determined by inductively coupled plasma-mass spectrometry (ICP-MS). The results indicate that the activity concentrations of 238U and 232Th ranged from 0.64 to 0.80 Bq/L (averaging 0.71 Bq/L) and 0.91 to 1.45 Bq/L (averaging 1.17 Bq/L), respectively while 40K and 137Cs had activity concentration values below detection limit. The chemical compositions (Na, Mg, Ca, Mn, Fe, Ni, Cu, Zn, As, Se, Cd, Sb, Ba, Pb and U) and activity concentration values of 232Th, 40K and 137Cs are below the World Health Organization (WHO) permissible limit whereas that of 238U is slightly above the recommended limit. Varimax rotated Principal Component Analysis (PCA) revealed three hydrogeochemical processes operative in the surface water system. Factors 1 and 2 are related to the interactions of groundwater with the associated geological matrix while Factor 3 indicates anthropogenic processes within the study area.