Earthshots: Satellite Images of Environmental Change

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» Salar de Atacama, Chile

If you like being connected to the world everywhere you go with a smartphone or other device, then you have a desolate salt flat in northern Chile to thank.

The salt flat is the Salar de Atacama, one of the largest sources of lithium, a key ingredient in rechargeable batteries. The rectangular shapes in these Landsat images indicate where lithium mining is taking place. The increasing use of smartphones, laptops, and electric cars that use lithium-ion batteries ensures an ever higher demand for the soft, silvery metal.

The salar is in Chile’s Atacama Desert, probably the driest place on the planet. Water leaves the salar only through evaporation, a process that leaves behind salts. The white color around the edge of the salt flat is clay and carbonate-rich material. The center of the salt flat consists of hard crusts of sodium chloride. Under this crust are brines that contain large amounts of lithium, potassium, magnesium, and boron.

Not completely devoid of a water source, the northern part of the basin is the San Pedro River delta. The San Pedro is an ephemeral stream, delivering small amounts of surface water to the basin from the north. The water originates from the Andes Mountains after infrequent storms. These flows form alluvial fans, visible around the fringes of the salt pan.

The scant vegetation appears red in these images, especially around springs at the northern edge of the salt flat. The salt flat itself covers about 3,000 square kilometers, almost the size of Yosemite National Park in California.

Salar is Spanish for “salt flat.”

Map of the featured area.


Some dry lakes have occasional inundations that partially dissolve the surface crusts. The center of the Salar de Atacama, however, is continually dry, so its surface is very rough.

An increasing number of evaporation ponds now sprawl across the salt flat. Large amounts of lithium-rich brine are pumped to the surface from up to 30 meters below the saline crust. Canals bring the brine to ponds for efficient evaporation in this dry, windy place. Potassium chloride, potassium sulphate, boric acid, magnesium chloride, and lithium chloride are left behind. The lithium chloride is treated with sodium carbonate to produce lithium carbonate, the primary ingredient in lithium-ion batteries.

The lithium concentration in the Salar de Atacama is the highest in the world. That, along with the fast evaporation rate, means the region has the planet’s largest deposit of economically recoverable lithium. Salar de Atacama has an estimated lithium content of 6.3 million tons.

The brine, which at first looks like dirty slush, is pumped to the surface and sent via canals to several evaporation ponds. The dry, windy climate makes for efficient evaporation and leaves behind concentrated salts, from which lithium can be extracted.

The ponds, which are about 10 feet deep, vary in color in the images because of varying amounts of salts in the water. The brighter ponds contain more concentrated salts. The deep blue ponds indicate more water content.

The lithium is reduced to a concentrate and then shipped by tanker truck to a refinery on the coast in Salar del Carmen. From there, it’s on to the rechargeable battery you depend on to power your smartphone.


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