'We don't want to let the industrial polluters off the hook, but we now think climate change is the culprit' -- scientist Gary Stern
AMUNDSEN GULF, N.W.T. -- Increasing levels of toxic mercury found in beluga whales, seals and polar bears may be due to climate change instead of just pollution from the south, scientists studying the Canadian Arctic believe.
Federal technician Joanne Delaronde raises water sampler for mercury testing.
Mercury levels in the organs of large animals in the Western Arctic have quadrupled over the past 25 years, according to tissue samples taken from animals killed by Inuit hunters.
Concentrations of mercury in beluga whale livers have been observed as high as 50 micrograms per gram, which is 100 times higher than the level considered safe for humans to eat.
Up until recently, environmental geochemists believed industrial pollution from the south was the sole culprit, because mercury is belched into the atmosphere from smokestacks around the world.
The entire Arctic basin acts as a reservoir for the heavy metal, which is ingested by plants and small animals and then passes up the food chain until it's concentrated in large predators.
But recent research on Arctic contaminants suggests the rapid increase in mercury concentrations in whales, seals and bears has more to do with how those animals are feeding in an Arctic that's rapidly losing its summer ice.
"We don't want to let the industrial polluters off the hook, but we now think climate change is the culprit," says Gary Stern, the chief scientist aboard the Canadian Coast Guard research vessel Amundsen, an icebreaker overwintering in Arctic waters south of Banks Island in the Northwest Territories.
Working in a lab on board the ship, University of Manitoba and federal fisheries researchers are measuring mercury levels in the Western Arctic's air, water, snow and ice, as well as samples of plants and animals.
While trying to find the source of the rapidly increasing mercury levels at the top of the food chain, they've all but ruled out the atmosphere.
Although the amount of mercury in the Arctic is not natural -- centuries of burning coal and other fossil fuels have raised levels 10 times above pre-industrial concentrations -- atmospheric mercury in the North has not increased significantly since the 1990s.
Stern and other researchers now believe the increasing levels found in beluga whales are actually due to rising temperatures and disappearing sea ice, which have boosted the productivity of the northern seas by creating a warmer, brighter and more nutrient-rich environment for tiny plants and animals to grow.
According to the theory, new sources of food in an increasingly ice-free Arctic are forcing larger predators to change their feeding behaviour, creating more links in the Arctic food chain.
That means more mercury gets concentrated at the top of the food chain, even though the overall amount of mercury in the ecosystem has not increased very much.
"It looks like a mercury mystery, that's for sure," says Stern. "But those are not mutually exclusive conditions."
Despite the theory, Stern says it's still important for industrial polluters to reduce the amount of mercury they emit around the world, as it will take centuries for contaminant levels to go back to normal in the Arctic.
Mercury can exist in the environment in both an inert and toxic form, with the latter known to cause neurological problems in human beings.
This has huge implications for Inuit who continue to live off the land and hunt whales, seals and polar bears. But for now, the environmental geochemists are encouraging northern people to continue to hunt and fish instead of stocking up on Kraft Dinner.
"If they stopped eating the belugas and other traditional foods, it would be more detrimental than going to the store and buying processed food," says Stern, noting Inuit who switch to southern diets are prone to high rates of diabetes.
"We want them to continue to eat what they've always eaten, because the threat from contaminants is still less than the threat posed by processed food."
In other words, mercury-laden muqtuq is still better to eat than M&Ms. Maybe they ought to sell beluga whale skin in vending machines.
bartley.kives@freepress.mb.ca
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