Over 250 million years ago, a mass extinction annihilated nearly all of Earth’s living species. Scientists have proposed many theories for why this occurred, and until now, the most widely accepted explanation for the event had been that volcanic eruptions burned through coal beds, releasing carbon dioxide and other fatal toxins into the environment.
But researchers at the University of Calgary in Alberta, Canada, have uncovered a potential new reason for the mass extinction: mercury.
The study, published in the academic journal Geology, notes that the mass extinction occurred during the time of greatest volcanic activity in the planet’s history. Mercury deposition rates in this period were up to 30 times higher than in today’s volcanic activity, the researchers found. Levels this high could have been catastrophic enough to wipe out life on the planet.
Normally, algae acts as a purifier of toxins.
“Typically, algae acts like a scavenger and buries the mercury in the sediment, mitigating the effect in the oceans,” says Dr. Hamed Sanei, lead author of the study. “But in this case, the load was just so huge that it could not stop the damage.”
The new research has the potential to change the way scientists view not only the Earth’s past, but also its future.
“We are adding to the levels through industrial emissions,” adds Dr. Benoit Beauchamp, another author of the study. “This is a warning for us here on Earth today.”
However, it also shows how the planet’s resiliency, as well as surviving life forms’ ability to adapt to harsh conditions.
“After the system was overloaded and most of life was destroyed, the oceans were still able to self-clean, and we were able to move on to the next phase of life,” Sanei says.