Increasing Forest Fires Pump Mercury into the Air

As wildfires grow in number and strength worldwide, they are unleashing mercury that has polluted wetlands in the north since at least the dawn of the Industrial Revolution.

These infernos in the north of North America are releasing mercury at levels up to 15 times greater than fires elsewhere in the continent. The key, researchers note, is that climate change is making northern wetlands more vulnerable to burning.

Mercury can damage the brain and lead to birth defects. Normally, atmospheric circulation carries mercury spewed from industry northward, where it settles down, for instance, in cold wet soils in Alaska and Canada.

"Peat lands have done us a real service by locking up mercury before and during the entire Industrial Age," researcher Merritt Turetsky, an ecologist at Michigan State University in East Lansing, told LiveScience.

Over the past few decades, forest fires are burning more frequently and intensely. In 2004 and 2005, Alaska and western Canada saw the largest wildfire seasons in recorded history. Increasingly, northern forests and wetlands also are growing drier due to climate change, Turetsky said, leaving them more vulnerable to fires.