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Asteroid impact acidified oceans: study

JAPANESE ANALYSIS:A Planetary Exploration Research Center team used a laser beam, plastic, tantalum foil and a rock to replicate the impact of an asteroid plowing into Earth


The space rock that smashed into Earth 65 million years ago, famously wiping out the dinosaurs, unleashed acid rain that turned the ocean surface into a witches’ brew, researchers said on Sunday.

Delving into the riddle of Earth’s last mass extinction, Japanese scientists said the impact instantly vaporized sulphur-rich rock, creating a vast cloud of sulphur trioxide (SO3) gas.

This mixed with water vapor to create sulphuric acid rain, which would have fallen to the planet’s surface within days, acidifying the surface levels of the ocean and killing life therein.

Those species that were able to survive beneath this lethal layer eventually inherited the seas, according to the study which did not delve into the effects on land animals.


It occurred when an object, believed to be an asteroid about 10km wide, whacked into the Yucatan Peninsula in modern-day Mexico.

It left a crater 180km wide, ignited a firestorm and kicked up a storm of dust that was driven around the world on high winds, according to the mainstream scenario.


Large species suffered especially: Dinosaurs, which had roamed the land for about 165 million years, were replaced as the terrestrial kings by mammals.




Critics say the collision was far likelier to have released sulphur dioxide than sulphur trioxide, the culprit chemical in acid rain. And, they argue, it would have lingered in the stratosphere rather than fallen back to Earth.

Seeking answers, a team led by Sohsuke Ohno of the Planetary Exploration Research Center in Chiba, Japan, set up a special lab rig to replicate — on a tiny scale — what happened that fateful day.



The team caused collisions ranging from 13 to 25 km per second (47,000kph to 90,000kph), and analyzed the gas that was released.

The research, reported in the journal Nature Geoscience, showed that sulphur trioxide was by far the dominant molecule, not sulphur dioxide.


The articles rapidly bound with the poisonous vapor to become sulphur acid “aerosols” that fell to the surface.



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