03.11.2022, 09:37 66881

Salt Lake Colors, Kazakhstan

Images | earthobservatory.nasa.gov

An astronaut aboard the International Space Station (ISS) took this photograph of a chain of small lakes in the treeless grassland, or steppe, of western Kazakhstan. The colorful lakes lie a few meters below sea level. This part of Kazakhstan is a lowland that slopes toward the Caspian Sea-300 kilometers to the south-which is itself about 27 meters (90 feet) below sea level.

Small settlements (such as Kumankol) dot these semi-arid landscapes, but they can be difficult to discern in satellite and space station imagery. Hundreds of such pastoralist settlements are spread out across rural Kazakhstan. A major road crosses the bottom of the photo.

The Ashiozek River, marked by many meanders, brings water south to the lakes. The river spreads out into a small delta, and water flows through these branches to lakes Aralsor and Zhalnak and other depressions further south. (For scale, Lake Aralsor measures 15 kilometers, or 9.5 miles, wide in an east-west direction.) The margin of a vegetated dunefield is visible in the lower left corner; dunes often accompany such lakelets in this region.

Evaporation increases the salinity of the water in this region, allowing different species of salt-loving microorganisms to thrive. The different salinity and temperature in each lake influence the dominant microbe species that flourishes. Different microorganisms display varying colors, as varying lake water depth accentuates or softens the tones. Exposed salt-and not an active microbial community-may explain the brilliant white of the smaller lake bed at the lower right.

The phenomenon of colorful neighboring lakelets occurs in all semi-arid subtropical zones, as demonstrated by astronaut images of Lake Eyre in Australia and Etosha Pan in Namibia. Evaporation ponds on the margin of the Great Salt Lake (engineered pans used for salt production) show the same kind of variable color differences. In most cases, red and orange colors indicate higher salt concentrations and microbial activity than blue-hued water.

Source: NASA

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