Mercury behind earth's last extinction

Japan Herald (IANS) Friday 6th January, 2012

Scientists have singled out mercury as one of the major factors behind the earth's greatest extinction 250 million years ago, obliterating most marine and land species.

'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,' says Steve Grasby, adjunct professor at the University of Calgary, Canada and study co-author.

'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,' adds Grasby, also research scientist at Natural Resources Canada, the journal Geology reports.

Benoit Beauchamp, professor of geology at Calgary, says this 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.

'Geologists, including myself should be taking notes and taking another look at the other five big extinction events,' says Beauchamp, also study co-author, according to a university statement.

During the late Permian, 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,' says lead-author Hamed Sanei, research scientist at Natural Resources and Grasby's counterpart at Calgary university.

'But in this case, the load was just so huge that it could not stop the damage.'