Find traces of mercury in the Mariana Trench – La Stampa


At about 9.7 kilometers below the surface of the Pacific Ocean, in the Mariana Trench, the deepest point on the planet, traces of anthropogenic pollution from mercury, a highly toxic substance, have been found. Experts from the Chinese University of Tianjin, who explored and analyzed the abyssal ocean waters, reported this during the Goldschmidt geochemistry conference. “It was a real surprise at such a deep depth, some previous studies had established that methyl-mercury can accumulate within a few hundred meters from the surface of the water, guaranteeing the safety of the marine fauna that inhabits the depths However, our research shows that this may not be true, “says Ruoyu Sun of the Chinese University of Tianjin.
“Mercury in ocean waters becomes methyl-mercury, the organic form of the element, which could be more dangerous due to a process known as ‘bioaccumulation’, whereby smaller fish feed on the toxic substance, which then it is assimilated by the larger animals that feed on small fish, until toxic substances reach our food chain “, explains the expert, adding that mercury can be implicated in environmental catastrophes and particularly harmful during the development of fetuses. “In Minamata, Japan, in the 1950s, for example, mercury caused severe neurological symptoms and birth defects for a large number of children. In 2016 and 2017, thanks to the use of water exploration vehicles deep, traces of this dangerous pollutant were found at 9.7 and 8.5 kilometers deep, in the Mariana Trench and in the Yap Trench, two of the most inaccessible places on Earth, “continues Sun.

Plastic in the Mariana Trench: the discovery at less than 10 thousand meters

“The isotopic footprint we found was unmistakable. Our results indicate that natural methyl-mercury at those depths is extremely rare, therefore what we found must be of anthropogenic origin,” comments the researcher. An American team, on the other hand, analyzed fish and crustaceans from the Mariana Trench and that of Kermadec near New Zealand, which reaches a depth of 10 km. “Our data indicate the presence of mercury in species that inhabit deep waters. The substance may have reached ocean animals due to rains,” says Joel Blum of the University of Michigan who led the expeditions. “Mercury is introduced into the environment from a variety of natural sources such as volcanic eruptions and forest fires, but anthropogenic activities, such as the combustion, extraction and production of coal and oil, are responsible for much of its diffusion, “comments Ken Rubin of the University of Hawaii. “Now, thanks to these studies, we know that mercury can reach even the most remote points on the planet. We have further confirmation of the profound impact that human activity can cause”, conclude the researchers.

What would the world be like without oceans? Animation on a scientific basis if a hole was opened in the Marianne Pit

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