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Increased Burning of Peatlands Boosts Mercury Emissions

Published by MAC on 2006-09-07

Increased Burning of Peatlands Boosts Mercury Emissions


7th September 2006

The boggy and cold peatlands of Alaska and northern Canada have long acted as atmospheric sponges, absorbing carbon and mercury from the atmosphere. But peatlands are becoming drier and burning more often, a new study finds, and toxic mercury is spewing back into the atmosphere, making its way to the land and waters of the northern hemisphere.

The study´s authors estimated global mercury emissions as 15-fold greater than previous studies that did not account for the vast amount of mercury stored in northern peat soils.

"With pervasive drying of peatlands, probably due to climate change, much of the carbon and mercury that took thousands of years to accumulate may simply go up in smoke," said Jennifer Harden, a U.S. Geological Survey researcher and co-author of the study. "It is important that researchers account for this increased mercury being unleashed into the atmosphere as we assess the possible effects of global warming."

The researchers reconstructed 20 years of mercury emissions and concluded that drought, water table, and fire severity governed as much as a 15-fold increase in mercury and carbon emissions across boreal forests in North America.

"Over a 20-year period from 1980 to 1999, fire-caused mercury emissions across the northern region averaged about 23 metric tons a year; during drought years, however, emissions approached industrial emissions of mercury in North America - about 210 tons of mercury per year," the study's authors said.

The research was published this week by American and Canadian scientists in the "Geophysical Research Letters."

They note that ongoing and projected increases in boreal wildfire activity due to climate change will increase atmospheric mercury emissions.

"While we´re being pretty careful to account for carbon emissions and energy-carbon feedbacks to global warming, perhaps our other eye should be on mercury, the toxic twin," Harden said.


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