Page 18 - How It Works - Book Of Amazing Answers To Curious Questions, Volume 05-15

Why is Lake Natron

so inhospitable?

Understand the natural phenomenon behind
Tanzania’s this colourful – and super salty – soda lake

ituated in Africa’s Great Rift was originally a much larger
Valley, Lake Natron’s bright freshwater lake, but as the hot, dry
S pink waters stand out in climate evaporated much of the
more ways than one. In addition to water, it shrank and became very
its eye-catching colour, the lake is salty. The water is also a very The lake’s salt crust changes colour
also hypersaline, meaning that it warm temperature at 40 degrees from red to pink or orange depending
on the microorganisms present
is supersaturated with salt. Celsius (104 degrees Fahrenheit),
Ash from the once volcanic but can sometimes reach a
mountains nearby has enriched the scolding 60 degrees Celsius (140
soil on the lake bed with natron, degrees Fahrenheit).
the chemical compound from The lake’s distinctive colour
which the lake gets its name. comes from the microorganisms
Natron consists mainly of sodium that thrive on the salt within, but
carbonate, a salt that dissolves in there aren’t many other creatures
the water to make it strongly that can survive these extreme
alkaline. This type of lake is known conditions. Only one species of fish,
as a soda lake, as its water has an the tilapia, is tough enough to live
extremely alkaline pH of between 9 in the lake, but most other animals
and 10.5. Acidic rain sometimes that venture into the water will die
reduces this value, but wet weather and become encrusted with salts
is erratic in the region. when water levels drop. The
Additional salts are also fed into natron, which was used in
the lake from nearby hot springs, Egyptian mummification, helps to
and because the lake has no outlet, preserve their bodies, causing eerie
it is all left behind as the water stone-like figures to occasionally
evaporates. In fact, Lake Natron wash up onto the shore.

The wonderful Most of the world’s lesser
wildlife of flamingos use Lake Natron
Lake Natron as their nesting site
One of the very few creatures that can
thrive at Tanzania’s hypersaline lake is the
flamingo. The birds take advantage of the
lake’s extreme conditions, which keep
their predators at bay. When the water
level is just right, salt islands are exposed
in the centre of the lake, providing the
perfect nesting site. If the lake is too dry,
predators are able to reach the young
birds, and if there is too much rain, the
nests can be flooded. The lake also
provides an abundant source of food, as
they feed on the blue-green algae, from
which pigments called carotenoids give Lake Natron is surrounded
the birds their bright pink colour. by freshwater wetlands
and salt marshes

18 How It Works