New research says restrictions on mercury in North America and Europe have significantly reduced atmospheric levels of the potent neurotoxin around the world, despite large emission increases in Asia.
University of Alberta researcher Vincent St. Louis, a co-author of a recently published paper, said the findings are a strong indication that regional environmental action can help and that countries don't have to all move at the same time to make a difference.
"We used to think we have to do something about this globally," he said Wednesday. "But it's sort of showing that, regionally, we can have some good impacts."
Mercury is a serious environmental contaminant. It's known to damage the lungs, muscles and even the brain. It persists in the environment and concentrates in animals higher up the food chain.
Scientists had previously thought that emissions of the naturally occurring element were stable or increasing, driven by Asia's growth in coal-fired power generation. But that didn't square with what researchers were finding in the atmosphere, where mercury levels have been declining at the rate of one or two per cent a year over wide swaths of North America and Europe.
"We were observing declines in mercury concentrations in the atmosphere, but when people were looking at emissions, they were saying emissions haven't really dropped off globally," said St. Louis.
He and his colleagues decided to take another look at how much mercury was actually entering the environment.
They found that recent research suggested growth in Chinese emissions had been overestimated, as had the amount of mercury released by small-scale gold mining in South America. Meanwhile, industries and governments in North America and Europe moved to sharply limit mercury emissions.
Companies started phasing out the use of mercury in manufactured products. Power generators turned to natural gas instead of coal. Many of those that didn't installed mercury scrubbers on their stacks. Equipment designed to remove other pollutants picked up some mercury as well.
The measures seem to have worked.
Recalculations found North American emissions actually fell by almost three-quarters between 1990 and 2010. In Europe, the drop was even more dramatic, at more than four-fifths.
Asian emissions, however, did increase by more than one-third.
But taken all together, mercury emissions around the world dropped by 30 per cent.
"That was one of the surprising things of this paper," St. Louis said.
The findings, he said, should offer encouragement to those dealing with difficult, global environmental problems.
"This is actually one of those good news stories. If we actually, actively, do something about reducing mercury emissions to the atmosphere, that results in less mercury being deposited to lakes."