Lake Natron

Lake Natron is a salt or alkaline lake in north Ngorongoro District of Arusha Region in Tanzania. It is in the Gregory Rift, which is the eastern branch of the East African Rift. The lake is inside the Lake Natron Basin, a Ramsar Site wetland of international significance. A small part of the lake is in Kenya. The lake is mainly fed by the Southern Ewaso Ng'iro River, which rises in central Kenya, and by mineral-rich hot springs. It is less than three metres (9.8 ft) deep. Its width depends on its water level. The lake is a maximum of 57 kilometres (35 mi) long and 22 kilometres (14 mi) wide. In the surrounding area rain is infrequent. Most of the rain occurs between December and May. The total rainfall is about 800 millimetres (31 in) per year. Temperatures at the lake are frequently above 40 °C (104 °F). High levels of evaporation have left behind natron (sodium carbonate decahydrate) and trona (sodium sesquicarbonate dihydrate). The alkalinity of the lake can reach a pH of greater than 12. The surrounding bedrock is made of alkaline, sodium-dominated trachyte lavas that were laid down during the Pleistocene period. The lavas have significant amounts of carbonate but very low calcium and magnesium levels. This has allowed the lake to concentrate into a caustic alkaline brine. The lake is home to a number of wading birds, notably flamingoes. They feed on small crustaceans that live in the lake. In some areas, all three species of Alcolapia can be found. Alcolapia are small fish. References