GEOCHEMICAL FRAMEWORK FOR WATER-QUALITY STUDIES IN SUB-SAHARAN AFRICA

The scope for using hydrogeochemical techniques in water quality studi es in Africa is reviewed as a background to a set of thematic papers. Water quality problems are emerging as a key issue in Africa either: i ) in view of the pressures of man-made pollution on finite resources; or ii) the existence of regions with naturally induced geological prob lems, for example fluoride endemic areas. Such natural problems are th e focus of this paper and the following topics were emphasised during a workshop in Sodere, Ethiopia: the need to determine natural baseline s as a means of recognizing anthropogenic pollution; the need for high quality samples and field data, but relatively basic analytical data; the use of chloride to assist in recharge estimation and water-balanc e studies; an understanding of depth stratification of water quality a s part of the design of well/borehole drilling programmes; the use of hydrogeochemistry in geothermal studies; the recognition of health and /or acceptabilty problems, especially for F, Fe, Mn, As, I and Al. Wat er quality standards for African countries need to be considered in th e context of local geochemical environments and some of the WHO limits , especially for major ions, may be unattainable owing to naturally hi gh total mineralization. Copyright (C) 1996 NERC.