EDMONTON, Alberta, Jan. 6 (UPI) -- An extinction event 250 million years ago that killed nearly all marine species may have had a previously unsuspected chemical cause, Canadian researchers say.
Scientists at the University of Calgary said the extinctions, usually blamed on rapid climate change, also may have been caused by an influx of toxic mercury in the global ecosystem.
"No one had ever looked to see if mercury was a potential culprit. This was a time of the greatest volcanic activity in Earth's history and we know today that the largest source of mercury comes from volcanic eruptions," Steve Grasby, co-author of a paper published in the journal Geology, said.
"We estimate that the mercury released then could have been up to 30 times greater than today's volcanic activity, making the event truly catastrophic," he said.
The study is significant because it's the first time mercury has been linked to the cause of the massive extinction that took place during the end of the Permian period, researchers said.
"Geologists, including myself, should be taking notes and taking another look at the other five big extinction events," study co-author Benoit Beauchamp said.
During the late Permian period, the researchers suggest, the natural buffering system in the ocean became overloaded with mercury, contributing to the loss of 95 percent of life in the sea.
"Typically, algae acts like a scavenger and buries the mercury in the sediment, mitigating the effect in the oceans," lead author Dr. Hamed Sanei said. "But in this case, the load was just so huge that it could not stop the damage."
