HYDROGEOCHEMISTRY AND ENVIRONMENTAL ISOTOPE INVESTIGATIONS OF THE NORTH DIAMARE PLAIN, NORTHERN CAMEROON

This paper discusses the results of environmental isotopes and major c hemical data for thirteen selected groundwater samples representative of the North Diamare Plain in the extreme north of Cameroon. The O-18 and H-2 concentrations for all the investigated groundwaters vary from -0.27 to -4.36 parts per thousand and from -7.1 to -26.6 parts per th ousand, respectively. In the conventional d(2)H-d(18)O diagram, the di stribution of data points indicates that most of the analysed groundwa ters have been affected by evaporation. Chemically, the groundwaters a re of mixed Ca-Na bicarbonate type, and display high concentrations of dissolved silica (84-116 mg l(-1)). As inferred from the saturation i ndex calculations and selected mineral stability diagrams, the groundw ater chemistry may be adequately explained by both the weathering of a lumino-silicate minerals and cation exchange between the groundwaters and clay minerals. (C) 1997 Elsevier Science Limited.