Found: Hiroshima Atomic Bombing Glass Fallout

The atomic bombing of the US military from Hiroshima on August 6, 1945 "was by far the worst event created by man," according to geologist Mario Wannier. "You have a city and a minute later you have no city." At least 70,000 people were killed by the initial impact; the final number of deaths, considering the radiation, could exceed 145,000. Wannier and his colleagues recently came across tiny remnants of this massive event on the beaches of the Motoujina peninsula in Japan. These glass particles formed as a result of the explosion and have since settled on the nearest beaches. They published their findings this week in the newspaper Anthropocene.

Wannier had studied beach debris from different areas in order to compare the health of different marine ecosystems, when some particles from the Motoujina Peninsula struck it as unusual. In addition to the particles generated by plants or animals, they were "aerodynamic, glassy and rounded" – they reminded him of what he had seen in Cretaceous-Paleogene (K-Pg) sediment samples, Geological marker of mass extinction cleared the dinosaurs about 66 million years ago. Research suggests that mass extinction was triggered by the impact of a meteorite, which would have projected crushed materials into the atmosphere, which then went back down into glass form.

But these particles of the Motoujina Peninsula were also very different from the K-Pg particles in several ways: some were rubbery, others had a multilayered glass shell. The variety reflected the wide range of materials present in the particles, identified by the electron microscope at the University of California at Berkeley. This beach is just an indication that the particles formed as a result of the Hiroshima bombing. An urban center presents a greater variety of materials, such as concrete, marble, stainless steel, and rubber, than a desert test site such as Trinity, New Mexico, where the first explosion nuclear power was tested. The resulting particles of this test, called trinitites, are much less diverse than what Wannier and his colleagues now call "Hiroshimaites". The presence of anorthite and mullite crystals in the particles, however, suggested that they had formed at temperatures warmer than 3,300 degrees Fahrenheit or 1,800 degrees Celsius.

Although this does not capture the magnitude of the destruction, researchers estimate that there are between 2,200 and 3,100 metric tons of particles per square kilometer of the beach (if sand has been measured since then). the surface and up to four inches below). Wannier says it's the first time that they've been studied in detail since the bombing, nearly 75 years ago.