Biogenic Silica Profiles in the Sediments of Large Tropical Lakes: Examples from East Africa
Profiles of the abundance or mass accumulation rate of biogenic silica in sediment cores can provide important insight into the past productivity of diatoms and the climatic influence on a lake basin through time. While primary production of diatoms in the overlying waters can influence the burial rate of diatoms, other factors need to be considered as well. The geochemical mass balance of dissolved silica in the lake system is one such factor that plays an important role in controlling the rate at which diatoms can be buried in the lake sediments. Examples are provided from Lake Malawi and Lake Victoria, East Africa, that demonstrate how the rates of input and outflow of dissolved silica are related to biogenicsilica profiles in the sediments, and how conclusions were drawn on past environmental conditions in these large tropical lakes.