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According to new research, unusual and abundant glassy spheres found in the sandy beaches near the Japanese city of Hiroshima are remnants of the 1945 atomic bomb explosion.
On August 6, 1945, an American bomber B-29 dropped an atomic bomb on Hiroshima. In an instant, some 80,000 people were killed. The explosion and subsequent fire storms destroyed an area of more than 10 square kilometers, damaging more than 90 percent of the city's buildings.
But what goes up must eventually come down. The new study published this week in the scientific journal Anthropocene constitutes "the first recorded and the first published description of the fallout resulting from the destruction of an urban environment by an atomic bombing," according to the authors of the new document. The works show that the nearby beaches of the Motoujina Peninsula in Hiroshima Bay are surprisingly covered with fallout debris up to a depth of about 10 cm.
Hiroshima City and Bay Area with location of the Atomic Bomb Hypocenter. (Image: M. A. Wannier et al., 2019 / Anthropocene)
Described as "aerodynamic size debris of millimeter size", these particles included glass spheroids, glass filaments and molten composite compounds. The debris reminiscent of the spherical particles found in the soil layer associated with the impact of the meteor that caused mass extinction 66 million years ago, as well as the particles found in the area where the states United States has tested the atomic bomb for the first time, according to the newspaper. author, geologist Mario Wannier. However, unlike these particles, those found near Hiroshima were filled with materials such as iron, steel and rubber.
"To the surprise of finding these particles, the big question for me was: you have a city and a minute later you have no city. The question was: "Where is the city – where is the material?" It's a treasure to have discovered these particles. It's an incredible story, "Wannier said in a statement from the Berkeley Lab.
In 2015, Wannier was sifting sand particles that he had pulled from a beach just outside the city of Hiroshima. He was looking for marine life, but the strange glassy spheres of the mixture reminded him of the particles found in 66-million-year-old Cretaceous-Paleogene (K-Pg) sediment samples. The glassy spheres had a diameter of between 0.5 millimeters and 1 millimeter. Some were merged and others were shaped like a tear. But unlike the spheroids extracted from K-Pg sediments, these particles contained a surprising diversity of materials coated with several layers of silica. Intrigued, Wannier returned to the area to collect more beach samples.
In every kilogram of sand taken from the beach on the Motoujina Peninsula, Wannier and his colleagues at the University of California at Berkeley found that spheroids and other unusual glass particles accounted for 0.6 to 2.5% of the total. the sample. Extrapolating this means that every square kilometer of beach to a depth of about 10 centimeters contains 2,300 to 3,100 tons of these particles. That is to say, the elements that once made up the city of Hiroshima.
Using both conventional and scanning electron microscopes, and with the help of Berkeley mineralogist Rudy Wenk, the researchers detected six distinct morphological particle types, ranging from clear glass to rubber-like substances. The team discovered traces of aluminum, silicon, calcium, carbon and oxygen, as well as traces of building materials such as pure iron and steel. The composition of these debris is consistent with materials that were common in Hiroshima at the time, including concrete, marble, stainless steel and rubber.
According to research, these particles formed under extreme conditions, in which temperatures reached 1830 degrees Celsius (3,330 degrees Fahrenheit). The tremendous explosion transformed the crushed materials into liquid, casting the melted materials into the sky. Once at high altitude, the various particles crashed, which resulted in the complex agglomerations observed by the researchers.
The authors of the new study admitted that some of this debris may have been caused by other processes, such as a fire at a nearby Mazda plant in 2004 and a local site where fireworks were reported. artifice are presented each year. That said, "no alternative scenario to the A bomb explosion can provide a consistent explanation for all of our observations," the authors noted in the new study, concluding that:
This study interprets the large volumes of fallout debris generated under extreme temperature conditions as products of aerial detonation by the Hiroshima Atomic Bomb of August 6, 1945. The chemical composition of the cast debris provides clues to their origin, particularly with regard to urban building materials. This study is the first published publication and the description of the fallout resulting from the destruction of an urban environment by an atomic bombing.
As indicated, similar spheroids were found at the Trinity test site in New Mexico. But these glasses, called trinitite, were devoid of the chemical compounds found in the samples taken near Hiroshima. As a result, the authors of the new study dubbed the new material "Hiroshimaites" because of its distinct and diverse chemical composition.
Researchers would like to explore the soils near Nagasaki to determine if there are similar particles.
Selected Image: Mr. M. A. Wannier et al., 2019 / Anthropocene
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