Chemical composition of the small rivers of the north-western part of LakeTanganyika

The chemical composition of water in 13 small rivers of the north-western p art of Lake Tanganyika was studied over a 15-month period. The factors infl uencing the water chemistry were studied by cluster analysis. On the basis of major ion concentrations three groups of rivers could be identified. Ion ic differences between the groups depended on source altitude which was str ongly related to pH, water temperature, conductivity, nutrient content and weathering intensity of dolomite - and pyrite-containing bedrock. These res ults are in agreement with the riverine inputs of nitrogen to Lake Tanganyi ka calculated by Hecky et al. (1991), but are ca. 30% lower than their esti mated inputs of phosphorus and silicon.