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Science/Tech See other Science/Tech Articles Title: Volcanic mercury contributed to mass global extinction Canadian scientists probing ancient chemical deposits on the shores of a High Arctic lake have shed new light on the greatest mass extinction in Earth history — the "Great Dying" that wiped out about 90 per cent of the planet's species 250 million years ago. Sampling layers of sediment on Nunavut's Axel Heiberg Island that contain fallout from a series of colossal volcanic eruptions in Siberia during that time, researchers with the University of Calgary and Geological Survey of Canada found evidence of enough mercury pollution to have "overwhelmed" marine ecosystems and contributed to the massive global die-off at the end the Permian age. "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," said federal geologist Steve Grasby, also a University of Calgary researcher and co-author of a paper on the Canadian discovery published in the latest issue of the journal Geology. "We estimate that the mercury released then could have been up to 30 times greater than today's volcanic activity," Grasby added in a summary of the study, calling the event "truly catastrophic" on a planetary scale. Fellow University of Calgary and GSC scientist Hamed Sanei, lead author of the Geology paper, told Postmedia News on Tuesday that the team's findings at Axel Heiberg's Buchanan Lake "complement" rather than contradict recent studies by Canadian and other research teams suggesting sudden and profound climate change caused the great Permian extinction event, which occurred about 20 million years before dinosaurs evolved. "We don't say mercury was the only culprit," Sanei said. "It was a chain of events — various things happened." But the massive pulses of mercury and other chemical discharges from the Siberian volcanoes had a "massive effect" on organisms around the world, he said. The continents formed a single mass, called Pangea, during the Permian era. At the time of the greatest volcanic activity, the area of ancient seabed that today forms the Buchanan Lake outcrop was "directly downwind" of the eruptions in present-day Siberia and "in the path of the destruction," Sanei noted. Mercury would have been deposited in the ocean via rain or snow, gradually accumulating in a marine environment that was also experiencing other severe chemical and climatic disturbances, he added. The mercury would "get into the organic cycle, form toxic compounds, get into the food chain and actually kill living cells," said Sanei. Sanei, Grasby and study co-author Benoit Beauchamp collaborated on a paper last year that first identified coal ash deposits at Buchanan Lake as direct evidence of the volcanic catastrophe underlying the Great Dying. And in November, another University of Calgary geoscientist, Charles Henderson, co-authored a study in the journal Science with colleagues in China that showed how the mass extinction unfolded as part of a "runaway greenhouse event" marked by widespread wildfires, ocean acidification and soaring temperatures. Read more: www.canada.com/technology.../story.html#ixzz1j7ExlYGJ Post Comment Private Reply Ignore Thread Top • Page Up • Full Thread • Page Down • Bottom/Latest
#1. To: Tatarewicz (#0)
Earth's Newest Island, Burped from a Volcano, Is a Keeper Earth's newest island is here to stay.
No, this story is wrong. Mercury is good for you, that's why we start pumping it into children the day they're born and continue it until the day they die. That's why we put it in our mouths as fillings in our teeth. Mercury is inert and safe. The only way mercury can be made dangerous is if a microgram of it is sealed in a small glass tube, called a CFL lightbulb, which is a weapon of mass destruction that is 100% lethal. |
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