Poison ice

As the sea ice melts, a toxic stew of mercury and synthetic chemicals is
seeping into the Arctic food web, harming the area's people. We may be next.
By Elizabeth Grossman
April 30, 2008 | ARCTIC OCEAN -- Over 300 miles north of the Arctic Circle,
in the polar dark of a December morning, University of Manitoba Ph.D. student
Jesse Carrie is out on the frozen Beaufort Sea, collecting ice samples to
measure for mercury and pesticides. Lowered by crane from the deck of the
icebreaking research vessel the CCGS Amundsen, and accompanied by a rifle
bearer who keeps watch for polar bears, Carrie extracts ice cores and vials of
frigid water. Carrie is part of a $40 million International Polar Year scientific expedition, the first
ever to spend the winter moving through sea ice north of the Arctic
Circle. The expedition's labor-intensive work is essential to
understanding the impacts of global warming.
As the Amundsen cuts through ice across the top of the globe, Carrie and his
fellow researchers are uncovering evidence of a disturbing fallout of climate
change. They are finding toxic contaminants, some at remarkably high levels,
accumulating in this remote and visually pristine environment. Although there
are no industrial sources in the Arctic, residents of the Far North have some
of the world's highest levels of mercury exposure, some well above what the World Health Organization considers safe. High levels of
mercury -- a powerful neurotoxin -- are being found in Arctic marine wildlife,
including ringed seals and beluga whales, both staples of the traditional
Northern diet. Levels in Arctic beluga have increased markedly in recent years.
When coal is burned in power plants in the U.S.,
China
and elsewhere, mercury is released into the atmosphere. Airborne, mercury can
travel great distances before settling to the ground, or into lakes, rivers and
oceans. Air and ocean currents, propelled by weather patterns and storm
systems, sweep the mercury north. But the recent increases in Arctic mercury
outpace and cannot be explained by smokestack emissions alone, says Gary A.
Stern, a senior scientist with Canada's Department of
Fisheries and Oceans, professor at the University of Manitoba and co-leader
of the Amundsen expedition. Rather, signs point to global warming and other
disruptive impacts of climate change.
As temperatures rise, causing sea ice, permafrost and snow to melt, the
mercury that had been frozen in place is now being released, causing exposure
up and down the food web. "Climate change alters exposure in the north and
increases the system's vulnerability," says Robie Macdonald, a research
scientist with Canada's
Department of Fisheries and Oceans.
Yet the Arctic researchers are routinely recording a lot more than mercury.
They are seeing synthetic chemicals such as the brominated flame retardants
known as PBDE's (used in upholstery, textiles and plastics), as well as
perfluorinated and chlorine compounds. And while long banned in many countries,
lingering amounts of DDT and PCBs continue to turn up in people and animals in
the Far North. Of concern due to their persistence and ability to accumulate in
plant and animal tissue -- particularly the fat prevalent in Arctic animals --
these chemicals are also known to disrupt the endocrine hormones that regulate
reproduction and metabolism. Some are considered carcinogens.
Alaskan polar bears, for instance, have some of the highest levels yet found
in Arctic mammals of hexachlorohexane (HCH), a pesticide used to kill fungi on
food crops. Carrie's ice samples, collected hundreds of miles from any
agricultural sites, contain HCH. Polar bears also have some of the highest
recorded levels of perfluorinated compounds, chemicals used in waterproofing
and in fire and stain retardants. Indigenous people in both the Canadian and
Greenland Arctic have some of the world's highest exposures to these persistent
pollutants.
In the summer of 2007, Arctic sea ice reached a record low. Scientists
monitoring the 2008 winter ice pack suspect this year's summer ice may also be
remarkably low. As David Barber, Canada Research Chair in Arctic system science
at the University
of Manitoba, puts it,
"Well over a million years of all ecosystems evolved to take advantage of
this ice cover." With markedly less substantial sea ice cover, the
hemispheric system is being thrown off balance, prompting changes that are
increasing the load of contaminants in the Arctic.
As Stern explains, increased snowmelt, runoff and erosion in the Mackenzie River Basin
are also now washing naturally occurring mercury into the Beaufort
Sea. At the same time, disappearing sea ice leaves more water
exposed to sunlight, increasing the growth of marine microorganisms and tiny
plants like algae. This accelerates the process that turns mercury into its
highly toxic form called methylmercury, which accumulates in marine mammals and
fish traditionally eaten by residents of the Arctic.
"These changes are happening much faster than anticipated," Stern
says one morning on the Amundsen.
Decreasing sea ice is changing other dynamics of the Arctic ecosystem.
Seasonal climate changes are pushing some animals farther to find food and
prompting some to alter what and when they eat. "With climate shift
changing availability of ocean nutrients, some birds that used to fly 50 miles
to eat now have to fly 100," says Macdonald. "This means storing more
fat, magnifying -- or concentrating -- the contents of the fat, resulting in
stress to both birds and their chicks." Because fat cells serve as a
reservoir for many contaminants, when broken down to release energy, the toxics
are also released, exposing animals from within.
In addition, says Macdonald, "Migrating fish bring with them the
contaminants they've hoovered up in the ocean. When the fish spawn, they
release the contaminants." Similarly, fish-eating birds can take up these
pollutants that they then excrete. It's possible, he says, that animals
themselves might be adding to the transport of contaminants.
"The food web is quite important in terms of where contaminants are
found," says Derek Muir, a senior scientist in aquatic ecosystems research
with Environment Canada. Warmer temperatures and shorter ice
seasons -- in lakes as well as the Arctic Ocean
-- could alter what happens at the bottom of the food web in ways that affect
how contaminants move up the food ladder, he explains. "Warming,"
says Muir, "could deliver more contaminants up the food chain to top
predators, and result in high levels of contaminants in very remote
areas."
Because top predators are important traditional food for Arctic people,
humans are at the top of the food web. "There is absolutely no doubt of
exposure of pollutants with harmful effects to some groups," says Eric
Dewailly, professor of social and preventive medicine at Laval University,
who works with the International
Network for Circumpolar Health Research. There are local sources for some
metals and pollutants, but most of the persistent organic pollutants in the Arctic come "100 percent from the outside," he
says. Dewailly notes that because people are exposed to mixtures of
contaminants, it's hard to isolate the precise impact of a single one. However,
studies are now being conducted in Canadian Arctic communities to investigate
links between contaminants and cardiovascular, neurological, reproductive and
immune system.
Climate change is having another hazardous effect on indigenous people.
Warming temperatures have caused changes in ice conditions and migration
patterns that determine where people hunt and fish. In some northern
communities, these changes have begun to push people toward greater dependence
on supermarket food, which in remote Arctic villages can be extremely limited.
Research by Grace Egeland, Canada Research Chair in nutrition and health at McGill University,
shows that traditional Arctic foods tend to provide more protein, vitamins and
minerals than typically available local market food, which is usually higher in
carbohydrates, fat and sugar. "These people are feeling so many pressures
of transition that they're now at risk," says Egeland of the Arctic's indigenous communities. "There's a human
right to food without elevated contaminants," says Egeland. "Based on
what we know now, why wait to count the adverse events. Why wait until it's too
late?"
But what kind of action should be taken? Can the brakes be put on the
cascading impacts of climate change? "If we could slow it down we
would," says Barber of the shrinking sea ice. "But we can't do that
now; there's too much inertia in the system."
Can we reduce the impact of the pollutants? "We can control persistent
organic pollutants," says Muir. It's well documented that when hazardous
chemicals -- including mercury -- are taken out of use, environmental levels
decrease. And if affected populations are sufficiently healthy, they will
recover.
Yet the key to controlling these pollutants, says Muir, is knowing which are
persistent, toxic, likely to climb the food web and travel long distances. Muir
explains that of the 30,000 or so chemicals now in wide commercial use, only
about 4 percent are routinely monitored. Environmental and health impacts of
about 75 percent of them have not been studied at all. Meanwhile, these
invisible substances are moving to and through the Arctic.
And what happens in the Far North, says Stern, may well presage what's to come
farther south. "It's the canary in the coal mine," he says.