Threats to the salinity balance from increased siltation influxes will come from more projected logging in Natron watersheds and a planned hydroelectric power plant on the Ewaso Nyiro across the border in Kenya. The area around the salt lake is not inhabited but there is some herding and some seasonal cultivation. This has allowed the lake to concentrate into a caustic alkaline brine. The lavas have significant amounts of carbonate but very low calcium and magnesium levels. The surrounding bedrock is composed of alkaline, sodium-dominated trachyte lavas that were laid down during the Pleistocene period. The alkalinity of the lake can reach a pH of greater than 12. High levels of evaporation have left behind natron (sodium carbonate decahydrate) and trona (sodium sesquicarbonate dihydrate). Temperatures at the lake are frequently above 40 ☌ (104 ☏). The surrounding area receives irregular seasonal rainfall, mainly between December and May totalling 800 millimetres (31 in) per year. The lake is a maximum of 57 kilometres (35 mi) long and 22 kilometres (14 mi) wide. It is quite shallow, less than three metres (9.8 ft) deep, and varies in width depending on its water level. The lake is fed principally by the Southern Ewaso Ng'iro River, which rises in central Kenya, and by mineral-rich hot springs. Numerous near-white salt-crust "rafts" pepper the shallowest parts of the lake (inset). Fault scarps and the Gelai Volcano can also be seen. The lake is within the Lake Natron Basin, a Ramsar Site wetland of international significance.
It is in the Gregory Rift, which is the eastern branch of the East African Rift. Story by Kathryn Hansen.Lake Natron is a salt or alkaline lake located in north Ngorongoro District of Arusha Region in Tanzania. NASA Earth Observatory images by Joshua Stevens, using Landsat data from the U.S. And when the waters recede during the dry season, flamingos favor the area as a nesting site, as it is mostly protected from predators by the perennial moat-like channels and pools of water. Small, salty pools of water can fill with blooms of haloarchaea-salt-loving microorganisms that impart the pink and red colors to the shallow water. While the environment is too harsh for most common types of life, there are some species that take advantage of it.
The mixture moves through the ground via a system of faults and wells up in more than 20 hot springs that ultimately empty into the lake. Volcanoes, such as Ol Doinyo Lengai (about 20 kilometers to the south), produce molten mixtures of sodium carbonate and calcium carbonate salts. Evaporation usually exceeds that amount, so the lake relies on other sources-such as the Ewaso Ng’iro River at the north end-to maintain a supply of water through the dry season.īut it’s the region’s volcanism that leads to the lake’s unusual chemistry. In a non-El Niño year, the lake receives less than 500 millimeters (20 inches) of rain. In these images, you can see the deepest water along the perimeter of the lake bed, the location of lower-elevation lagoons. They show the lake on March 6, 2017, very early in the rainy season that runs from March to May. The Operational Land Imager (OLI) on Landsat 8 captured these natural-color images of Lake Natron and its surroundings. The lake is mostly inhospitable to life, except for a few species adapted to its warm, salty, and alkaline water.īut you don’t need to visit the lake in person to see its stunning, seasonal color. Not many people venture near the shores of Lake Natron in northern Tanzania.
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