Why Is The Dead Sea So Salty?

Salt crystals on the Dead Sea coastline.

Also known as the Sea of Salt, the Dead Sea is a body of water that is situated in the Jordan Rift Valley and surrounded by Jordan, Israel, and the West Bank. Despite what its name might suggest, the Dead Sea is actually a landlocked salt lake as opposed to a true sea. Primarily fed by the Jordan River, the Dead Sea has a surface area of about 234 sq mi, a maximum depth of 978 ft, a length of approximately 31 mi, and a maximum width of about 9.3 mi. The Dead Sea is one of the world’s saltiest bodies of water, with a salinity of 34.2% in 2011. To put that figure into perspective, the salinity of the sea is at least nine times that of the ocean. Additionally, the Dead Sea is too salty to support plant or animal life, which makes its name appropriate. In some parts, especially the shores, the salt builds up so much that it is possible for a person to sit on top of the salt layer.

Source of High Salinity Level

The Dead Sea's salt comes primarily from nearby rocks that dissolve into the lake. These rocks dissolve due to the acidity in rainwater, which then creates ions from the dissolved rock particles. Most ions are chloride and sodium ions, which end up accumulating in the Dead Sea as salt. As more and more salt enters into the sea, the water reaches a point when it cannot dissolve any more salt, which is known as the saturation point. After the saturation point, excess salt settles on the seafloor. Experts estimate that the saturation and subsequent accumulation of solid salt start at about 300 ft.

In recent years, the salinity of the Dead Sea has increased as more and more water from the Jordan River becomes diverted for both domestic and agricultural use. As a result, there is less fresh water to dissolve the excess salt, making the lake even more saline. This diversion is combined with high temperatures in the region, which contribute to high rates of water evaporation from the lake. The mean average temperature in the summer ranges between 32 °C and 39 °C. By contrast, the amount of average rainfall received in a year is less than two inches.

These factors all contribute to a steady decrease in the size of the Dead Sea, and experts claim that the lake is receding by about three feet each year. Since the turn of the 20th century, it has receded by roughly 100 feet. However, it is crucial to note that even without water diversion and warming temperatures, the Dead Sea has naturally receded before. It is estimated that the Dead Sea almost completely dried up during an interglacial period approximately 120,000 years ago.

Freshwater Springs Underneath the Dead Sea

There are other interesting aspects of the Dead Sea beyond its unusually high salinity level. In 2011, during a scientific expedition with specialized diving equipment, scientists discovered freshwater springs below the sea. These springs were surrounded by colonies of microbes that suggest the highly saline lake can support certain forms of life.


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