Science behind the Similar Ridges on Salt Flats Worldwide

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• In a new study, researchers from Austria, Germany, and the U.K. have attempted an explanation for salt flats formations.

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• Salt flats across the world share a similar pattern of ridges that form in a patchwork of pentagons and hexagons.
• The pattern is always a meter or two across and occurs regardless of local environmental conditions, mineral chemistry, soil type, and other factors.
• These captivating patterns have been discovered as far apart as Bolivia, Chile, China, India, Iran, Tunisia, and the U.S.
• The findings have suggested that the salt always crenellates in these shapes and at these sizes, irrespective of the local environmental conditions.
• The findings are important to know the underlying mechanism because salt flats have significant effects on both humans and the climate.

What are Salt Flats?

• A salt flat is a natural landscape in which a large area of flat land is covered by salt. 
• It forms from a natural water body whose recharge rate is lower than the evaporation rate.
• Over time, all the water evaporates, leaving behind dissolved minerals, usually salts.
• The world’s largest salt flat is the Salar de Uyuni in Bolivia, which contains more than half of the planet’s lithium reserves.

Formation of Shapes

• The researchers have hypothesized that the salt on the surface is influenced by the salt flowing through the soil below.
• The salt penetrated deeper into the soil exactly below the ridges and remained shallow under the flat areas.
• The researchers have found that the salty groundwater flows deeper into the soil along vertical sheets below the ridges, not throughout.

Key Findings:

• If the rate of salt deposition on the surface is sufficiently high, the denser groundwater will sink down, and the less-saline, less-dense groundwater will rise to the top.
• Over time, there will be more saline groundwater rising up towards the surface through the convection cells than through other parts of the soil, resulting in the salt accumulating on the surface and forming the narrow ridges that make up the polygons.
• The computer model indicates that the subsurface convection is relatively insensitive to salt chemistry, and over time, the convection columns grew to have a stable width of 1-2 m.

Importance of the findings:

• The theory and results matter because winds blowing over salt flats carry some of the salt with them as particulate matter, causing significant respiratory problems.
• To mitigate the deleterious effects of salt flats, experts have recommended covering them in a shallow layer of water.
• Salt suspensions are important aerosols that reflect sunlight, and saline lakes around the world are shrinking, so more accurate climate models will need to better understand the sources of salt.

Source: TH