Mercury Rising

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All that has been known for a while, but the game changer was the recent study of Northeastern songbirds. A group headed by Evers had been worried for some time that mercury's reach was greater than it seemed, particularly in the Northeast, which is downwind from the power plants of the Midwest and Canada. Mercury from those plants' smokestacks could find plenty of bacteria in water, leaves and sod to make the toxic conversion to methylmercury. Netting 178 species of songbirds and testing their blood and feathers, Evers found that all of them were indeed contaminated, some in concentrations exceeding 0.1 parts per million. That doesn't sound like much, but it's a lot higher than it ought to be, and it's surely on the rise. So far, the toxin hasn't disrupted the birds' reproductive cycle, but researchers fear that it will before long. What's more, if the birds are contaminated, so are other animals that eat the same diet--not to mention predators that eat the birds. Says Evers: "It creeps up the food chain and continues to biomagnify as it goes."

The wetlands study darkened the picture further. Marshes in Alaska and northern Canada are natural sinks for mercury, which chemically adheres to damp peat and readily converts to the methyl form. That is not a problem as long as the mercury stays put. But increasingly frequent droughts--a likely consequence of global warming--have led to increasingly frequent wildfires, causing wetlands to release centuries' worth of collected mercury in one toxic breath. "There's mercury that's been accumulating since the dawn of the Industrial Revolution," says ecosystems ecologist Merritt Turetsky of Michigan State University, who has been studying the problem. "During droughts, you get a meter-thick carpet of dry peat in some places, and all you need then is a match. Lightning usually provides that."

As global mercury levels rise, more and more species are being affected. A recent study by investigators at Denmark's Natural Environmental Research Institute showed that mercury measurable in the fur of Greenland polar bears is 11 times higher than it was in baseline pelts preserved from as early as the 14th century. This fall the National Wildlife Federation will release a survey of more than 65 recently published studies showing elevated mercury in more than 40 species, many of which had been thought to be in little danger. Some, including common loons and bald eagles, are already showing signs of behavioral and reproductive changes associated with mercury poisoning.

Cleaning up the mess is the responsibility of the species that made it, and that job starts with coal. The 440 coal-fired power plants in the U.S. produce about 48 tons of mercury a year--40% of the nation's total output, by some estimates. The Clinton Administration did not attack the problem until its final year, when it issued a proposal that would have required a 90% cut in power-plant mercury by 2008. President George W. Bush has discarded the Clinton rule in favor of a looser standard that would result in only a 70% reduction by as late as 2025. What's more, Bush weakened the Clean Air Act's new-source-review rule, which requires power-plant owners to install the best available pollution controls when they make major upgrades that result in increased emissions.