00:00Salt gives a delicious taste to our chips and popcorn.
00:04But that's not all.
00:06It is used in household and industrial products,
00:09in cosmetics, fertilizers, water treatment and road asphalting.
00:14Every year, around 300 tons of salt are produced worldwide.
00:19But there is a problem.
00:21It's too much salt for our planet.
00:23You see, salt gradually rises to the surface
00:26from the oceanic rocks located deep down.
00:29And this process is quite balanced.
00:31Or it was, in the past.
00:33Man is disrupting this balance.
00:35Our demand keeps increasing
00:37and we throw too much salt into the soil,
00:39into the air and into the sea.
00:41And if this process continues uncontrollably,
00:44we could be faced with an existential threat.
00:47Yes, it's really serious.
00:49And a recent study by the University of Maryland confirms it.
00:53There is a phenomenon known as the natural salt cycle.
00:58It has existed for thousands of years.
01:00Salt rises naturally
01:02due to geological elevation
01:04and rock alteration.
01:06As a result, rocks disintegrate
01:09and release salt ions into the soil.
01:11Some of these ions are absorbed by plants and organisms.
01:15Others are carried by rivers
01:17that transport them to the oceans.
01:19Salt also penetrates the atmosphere
01:22through salt dust in dry regions
01:25and impurities in coastal regions.
01:28Salt is essential for man,
01:30animals and plants
01:32because our organism feeds on it.
01:34In short, we are a bit like electric systems
01:36controlled by salt.
01:38The soil needs salt to stay compact.
01:40Plants also need it in small quantities.
01:43It allows their metabolism to function properly
01:46to synthesize chlorophyll in sufficient quantities.
01:49However, an excess of salt is not a good thing.
01:52Nowadays, human activity disrupts the natural salt cycle
01:55because we bring it back to the surface of the planet
01:58much faster than before.
02:00This is the conclusion that researchers have come to
02:02after combining data from different sources,
02:05including the U.S. Geological Survey Mineral Annual Report
02:09and the world records on the composition of watercourses
02:12and salinity measurements.
02:15The main factor behind these changes
02:17is the extraction of the necessary salt,
02:19especially in the food industry.
02:21This is followed by acid rain,
02:23which accelerates rock alteration.
02:25These factors accelerate the production of salt
02:27on the surface of the planet.
02:29At present, the concentration of salt in the world is too high.
02:33The soil, plants and animals
02:35are not able to consume it completely.
02:38Worse still, some essential species
02:41cannot survive with this excess of salt.
02:44Their disappearance modifies biodiversity
02:46and could lead to the appearance of invasive species
02:49such as the common rose.
02:51This is a tall plant that invades coastal areas.
02:54There is also the zooplankton,
02:56an important oceanic species for the regulation of algae
02:59and which is extremely sensitive to salt.
03:02If this species begins to decline,
03:04it could disrupt global food networks.
03:07The excess of salt also turns agricultural lands into fridges.
03:11Recent reports have shown that
03:13about 13 million square kilometers of land
03:15are already affected.
03:17This is an area equivalent to four times the size of India.
03:21In some countries,
03:23huge areas become infertile because of this excess.
03:27In addition, excess salt is bad for health.
03:30Indeed, all this additional salt
03:32infiltrates underground waters,
03:34making them too salty for human consumption.
03:37This situation is particularly harmful
03:39to people who must follow a poor sodium diet.
03:43And I'm not just talking about table salt
03:45or sodium chloride.
03:46No.
03:47Other salts based on calcium and magnesium
03:49also infiltrate, generally,
03:51during the production of fertilizers and building materials.
03:54This gives us an awful chemical cocktail
03:56of different salts from various sources.
03:58And scientists do not yet know
04:00the effects that such a mixture can have on us,
04:03humans.
04:05Do you think it's time
04:07to reduce your salt consumption?
04:10Well, but do not completely eliminate it.
04:13In the 1930s,
04:15Dr. Robert Mackenz
04:17of the Department of Experimental Medicine
04:19at the University of Cambridge
04:21asked four volunteers
04:23to go completely salt-free for 10 days.
04:26They first had to sweat to evacuate the salt
04:28that remained in their bodies.
04:30Then, the scientist literally
04:32desalted everything they were allowed
04:34to eat and drink.
04:36Shortly after,
04:37the participants began to experience
04:39strange sensations.
04:41They realized that there was no longer much taste
04:43in what they were eating.
04:46The situation worsened.
04:48They began to feel tired,
04:51then they were quickly too exhausted
04:53to eat.
04:55They began to show signs of hyponatremia.
04:57This is when the sodium concentration
04:59in the blood is dangerously low.
05:01The blood cells thicken,
05:03the blood no longer managing to regulate
05:05the amount of water a cell must consume.
05:09If this problem is not treated,
05:11it can not only lead to epilepsy,
05:13but also have much worse consequences.
05:16At the end of the trial period,
05:18the participants received salty food.
05:21Miraculously,
05:23within a few minutes,
05:25they regained their sense of taste
05:27and their energy was restored.
05:29To tell the truth,
05:31all this is a bit terrifying.
05:33If this is what 10 days without salt means,
05:35imagine the disaster that would occur
05:37if there was no more salt at all.
05:39We would not last long,
05:41that's for sure.
05:43And it would be an endless drama,
05:45not only for us,
05:47but also for plants and animals.
05:49Because they need as much salt as we do.
05:51If our oceans suddenly lost all their salt,
05:53the underwater algae would disappear,
05:55which would reduce almost half
05:57the photosynthesis on the planet.
05:59The terrestrial plants would follow the movement.
06:01Shortly after the disappearance of salt,
06:03we would be confronted
06:05with a size problem.
06:07Too much carbon dioxide
06:09and not enough oxygen.
06:11Our climate would begin to fluctuate,
06:13with extremely hot and cold temperatures,
06:15and hurricanes would become
06:17incredibly powerful
06:19and destroy everything in their path.
06:21Fortunately, we still have salt in our stores,
06:23and its natural cycle
06:25could become more or less stable.
06:27Humanity knows
06:29and has been using salt since the dawn of time.
06:31It was used, for example,
06:33to make and preserve mummies
06:35in ancient Egypt.
06:37It was a product of value
06:39that was exchanged between the Phoenicians
06:41and other peoples of the Mediterranean.
06:43In ancient China,
06:45people knew more than 40 types of salt
06:47that they used for medicinal purposes.
06:49In medieval Europe,
06:51Venice became powerful
06:53thanks to its monopoly on salt.
06:55Its production and transportation
06:57favored the appearance of new cities
06:59and the construction of roads.
07:01Salzburg, the city of salt in Austria,
07:03is an excellent example of this.
07:05Today,
07:07salt continues to surprise us.
07:09For example,
07:11researchers from the Rosensteil School
07:13of Marine and Atmospheric Science
07:15at the University of Miami
07:17have recently discovered rare deep-water
07:19salmon pools in the Gulf of Aqaba.
07:21This is a northern extension
07:23of the Red Sea.
07:25These salty underwater lakes
07:27could reveal to us the secret
07:29of the formation of oceans
07:31millions of years ago.
07:33They could also give us clues
07:35about extraterrestrial life.
07:37Deep-water salmon pools
07:39are among the most extreme environments
07:41on Earth, and yet,
07:43despite their ultra-high salinity,
07:45their somewhat exotic chemistry
07:47and their total lack of oxygen,
07:49they are full of life.
07:51Researchers have even found
07:53bioactive molecules
07:55with potentially anticancer properties
07:57in the Red Sea.
07:59These oxygen-deprived pools
08:01are located near the coast
08:03and could contain information
08:05about tsunamis, earthquakes
08:07and sudden cruises
08:09that took place in the Gulf of Aqaba
08:11thousands of years ago.
08:13Salt even arrived in space.
08:15Finally, in a way.
08:17The Moon is like a comet
08:19that crosses the cosmos.
08:21Our natural satellite
08:23has a thin line of irradiated matter
08:25that our planet crosses
08:27directly once a month.
08:29However, according to a study
08:31published in the journal J.J.R. Planets,
08:33this lunar line
08:35would be made up of millions of sodium atoms.
08:37And as you already know,
08:39the chemical formula for salt
08:41is sodium chloride.
08:43These atoms
08:45are expelled from the lunar soil
08:47by meteorites, then pushed
08:49thousands of kilometers downstream
08:51by solar radiation.
08:53Several days a month,
08:55when the new moon is between
08:57the Earth and the Sun,
08:59the gravity of our planet
09:01drags this line of sodium
09:03into a long beam
09:05that wraps around our atmosphere.
09:07The line itself is harmless
09:09and invisible to the naked eye.
09:11But during these few days,
09:13the most powerful telescopes
09:15can detect the faint orange glow
09:17in the sky.
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