EFFECTS OF MICROBIAL ACTIVITY ON THE HYDROCHEMISTRY AND SEDIMENTOLOGY OF LAKE LOGIPI, KENYA

Lake Logipi is a saline soda and alkaline lake which marks the northern termination of the Suguta River drainage system. It also receives waters from streams, possible seepage from Lake Turkana, and hot springs. Present hydrochemistry and sedimentology is controlled by numerous factors including seasonal variations, composition of incoming waters, water depth and, above all, bacterial activity. Given the scarcity of Ca2+ and Mg2+ in the lake waters, bacterial activity seems to intensify the alkalinization of the waters which inhibits the deposition of organic matter and leads to the genesis of a poorly organic, zeolitic mud that reaches 1.5 m in tickness in the deepest part of the lake. This black layer may be overlaid with thin crusts of trona and halite which prograde over the basin from its southern bank when the lake is drying out and which are dissolved in the lake waters during the rainy season.