Abstract:
This paper reports concentrations of γ-emitter radionuclides (40K, 137Cs, 210Pb, 226Ra, 228Ra, 228Th and 234Th)
and some metals (Al, Cr, Fe, Co, Ni, Cu, Zn, As, Sr, Cd, Sb, Cs, Pb, Th and U) in surficial sediments from the
Ankobra, Pra and Volta estuaries, in Ghana. Artisanal gold-mining in the Ankobra and Pra basins promoted
moderate enrichments of As, Sb, Cu, Cs and Cr in their estuarine sediments, with respect to the reference
background of the Volta Estuary. Radionuclide concentrations were in the range found in the Earth’s crust.
Present data do not support any conclusion on their potential enrichments due to gold-mining activities.
Radionuclide isotopic ratios revealed a transfer of 228Ra from sediments to the water column. Pearson correlation
coefficient matrices showed different patterns, which were reasonably understood after novel approaches: i)
inter-estuaries comparison of slopes in the linear regressions of element-concentrations vs Al, Fe and Cs; ii) study
of Al-normalized concentrations of elements; iii) excess 210Pb informing on local sedimentary conditions. The
metal enrichments observed in the Ankobra and Pra estuaries are associated with the Fe-rich compounds in
sulphide ores (such as FeAsS) transported along the river course and deposited in the estuary.