Mercury to blame for the 'great dying'

Scientists probing ancient chemical deposits on the shores of a High Arctic lake have found that mercury was chiefly responsible for the 'great dying' that wiped out 90 per cent of the planet's species 250 million years ago.

Researchers from the University of Calgary and Geological Survey of Canada have discovered that mercury pollution 'overwhelmed' marine ecosystems, which contributed significantly to the global die-off at the end of the Permian age.

Steve Grasby, a University of Calgary researcher, said: "We estimate that the mercury released then could have been up to 30 times greater than today's volcanic activity."

The massive pulses of mercury and other chemical discharges were from a Siberian volcano, and were said to contribute significantly to a chain of events.

The findings come as oceanographers in the Arctic have discovered that the seabirds in the Southern Ocean have four times the mercury levels of aquatic birds elsewhere. The high levels are having detrimental effects on marine life, but the researchers have said many of the animals are evolving to cope with increased mercury.

Posted by Lauren Steadman