The "gigantic" freshwater reserve found under the Atlantic Ocean (and what hopes it offers for arid areas of the planet)
The bottom of the Atlantic Ocean hides a treasure much more valuable than any pirate ship: fresh water.
Although it sounds strange, a group of geologists from Columbia University in New York, says that on the northeast coast of the United States lies almost 3,000 cubic kilometers of fresh water trapped in porous sediments under the salt water of the sea.
The finding, although surprising, was something that was already suspected. Experts believe that these types of freshwater deposits are abundant, but very little is known about their volumes and their distribution throughout the planet.
Scientists believe that this aquifer is the largest aquifer ever found. They call it "gigantic".
According to his calculations, the reserve runs from the coast of the state of Massachusetts to New Jersey and covers about 350 km of the Atlantic coast in that region of the United States.
If the reserve were on the surface, it would form a lake of about 40,000 km2.
What are these aquifers, how are they formed and why can they be promising for humans?
How did you find it?
To detect the water reserve, the researchers used electromagnetic waves.
One clue they already had is that in the 70s, some oil companies that drilled the coast did not extract oil but fresh water. The researchers, however, did not know if they were just isolated deposits or something much larger.
Now, to know the area in detail, from a ship they launched probes to measure the electromagnetic field in the depths.
Salt water is a better conductor of electromagnetic waves than fresh water, so by the type of low conductance signals they received, they could conclude that there was fresh water down there.
They also concluded that the deposits are more or less continuous, from the coastline to some 130km offshore. They are mostly between 180 meters and 360 meters under the ocean floor.
How did the water get there?
Geologists believe that fresh water could be stored there in two ways.
On the one hand, it is believed that during the end of the Ice Age, large amounts of fresh water were trapped in rocky sediments, something experts call "fossil water".
But recent research shows that the reservoirs probably also feed on rainfall and bodies of water that seep through the sediments in the earth and reach the sea.
Can you drink?
Researchers say that in general, aquifer water is sweeter near the coast and more salty as it enters the sea. That can mean that with the passage of time both types of water are mixed.
Terrestrial fresh water usually contains salt in amounts of less than one part per thousand. This is the same figure they found in the aquatic reserve near the coast. In its external limits, the aquifer reaches 15 parts per thousand. In comparison, seawater typically has 35 parts per thousand.
According to the geophysicist Kerry Key, co-author of the study, if you wanted to use the water from the more distant parts of the aquifer, it would have to be desalinated for most of its uses, but, in any case, the cost would be less than processing water from sea.
Key's study suggests that these reserves could be found in many other parts of the world, and could supply fresh water to arid places that urgently need it.
"We probably do not have to do that in this region," Key says in a statement. "But if we can show that there are large aquifers in other regions, that could represent a resource in places like Southern California, Australia or Africa."