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Environment

Ethiopia's Salt Ponds May Contain One of the Few Places Life Cannot Survive on Earth

The Dallol pools are likely so hot, salty and acidic that even extremophile microbes are unable to enter.

By Nathaniel ScharpingDecember 4, 2019 9:00 PM
Dallol Header
Ethiopia's Dallol ponds, where conditions are so hot, salty and acidic that life cannot find a way. (Credit: Tanguy de Saint-Cyr/Shutterstock)

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In the salt pools of Dallol, in northern Ethiopia, life faces some of the most extreme barriers to survival anywhere on Earth. Not only are the colorful ponds hot and highly acidic, but they are located above a massive dome of salt, pushing salinity levels to 10 times those of the ocean or higher.

The combination of factors means that even extremophiles, bacteria adapted to harsh conditions, have trouble surviving. And new research hints that there are some places within Dallol where life simply cannot survive. Temperatures reaching above 200 degrees Fahrenheit, pH levels that dip below zero and hypersaline water create an almost unearthly trifecta that stymie even the hardiest microbes.

A team of researchers from France and Spain took samples from the ponds and surrounding areas over the course of two years and applied a battery of tests to look for signs of life. While some areas at Dallol saw a diversity of extremophile microbes, there were a few places where signs of life were entirely absent, they write in Nature Ecology & Evolution. Previous studies that indicated some microbes might live in these ponds were likely contaminated by bacteria on either the instruments or the scientists themselves, they say, or which blew in on the wind from elsewhere. 

Despite their hostile conditions, the ponds themselves are an impressionistic tableau of greens, yellows, reds and blues, which change constantly as new materials bubble upwards. Unlike the pools of Yellowstone, though, whose colors come from microbes, the Dallol ponds are tinted by the presence of various kinds of iron. The colors can change by the day as materials circulate, creating an ever-changing iridescent landscape — beautiful but deadly.

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