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article imageThe high human cost of 'clean' energy — We can't undo what's done

By Karen Graham     Sep 8, 2015 in Environment
Methylmercury, a potent neurotoxin, has been found to be especially high in Arctic marine life, but until recently, scientists were unable to explain why. A new study found the neurotoxin is a by-product of global warming and melting sea ice.
While many governments are turning to hydroelectric power to mitigate the effects of global warming, new research into the high methylmercury levels in Arctic sea life has led to the finding that it's a by-product of global warming along with melting of sea ice in Arctic and sub-Arctic regions. These findings pose a serious risk to northern ecosystems.
The study by researchers with the Harvard John A. Paulson School of Engineering and Applied Science (SEAS) and the Harvard T.H. Chan School of Public Health began as a review of an environmental impact assessment for the Muskrat Falls hydroelectric dam in Labrador, Canada.
The new dam will flood a large region upstream from an estuarine fjord called Lake Melville. Most communities along the shores of Lake Melville are mainly made up of indigenous people, and they rely on the lake as a primary source of food. Additionally, two-thirds of Lake Melville is part of Nunatsiavut, the first autonomous region in Canada governed by Inuit.
The Muskrat Falls hydroelectric development on the lower Churchill River in Labrador includes constr...
The Muskrat Falls hydroelectric development on the lower Churchill River in Labrador includes construction of an 824 megawatt (MW) hydroelectric dam on the lower Churchill River in Labrador, and more than 1,500 km of associated transmission lines and infrastructure that will deliver electricity to homes and businesses in Newfoundland and Labrador.
Nalcor Energy
Lake Melville is a saltwater extension of Hamilton Inlet on the Labrador coast, and is the largest estuary in the province, primarily draining the Churchill River and Naskaupi River watersheds. In 2011, when the environmental assessment report was published predicting there would be no adverse downstream effects on Lake Melville, the Nunatsiavut Government contacted Elsie Sunderland, associate professor of environmental engineering and environmental health, asking for help.
Now, four years later, what started as a review grew into a multi-pronged investigation. Scientists now know how methylmercury accumulates in the ecosystem, and how it impacts humans who depend on the ecosystem for food and other resources.
"Clean energy benefits the entire world but the costs of hydroelectric power are often assumed entirely by the Aboriginal communities who live next to these developments," said Sunderland. "Our research highlights some of the costs to the community with the goal of helping them plan and adapt to the changes that are about to occur."
What's Happening in Happy Valley Goose Bay
Research started in 2012, when the team took a 10-day journey across Lake Melville on the fishing boat, What's Happening. They spent their time measuring baseline methylmercury levels. Amina Schartup, one of the co-authors of the study said, “We found more methylmercury in the water than our modeling could explain."
“All of the methylmercury from the rivers feeding into Lake Melville and from the sediment at the bottom of the lake couldn’t account for the levels in the water. There was something else going on here," she added. But it was the levels of methylmercury in plankton that drew their attention. It was peaking from one to 10 meters below the lake's surface.
The readings closely correlated with readings found in the central Arctic Ocean, and it then became a question of why there were such high concentrations of the neurotoxin in plankton in both systems. It all came down to the eating habits of plankton.
The answer has to do with a layer called "marine snow"
When freshwater and saltwater meet, like in an estuary, or when sea ice melts, the salinity will increase as the water deepens. This causes layers to form in the water column called stratification. Organic material that normally sinks to the bottom of the ocean reaches a neutral buoyancy, so it doesn't rise or fall.
Marine snow falls gently on to a coral-covered shipwreck explored in the Gulf of Mexico in 2012 by t...
Marine snow falls gently on to a coral-covered shipwreck explored in the Gulf of Mexico in 2012 by the NOAA Ship Okeanos Explorer.
NOAA
This layer is called "marine snow." As it collects other small floating pieces of debris, it concentrates, forming a feeding zone for plankton. The bacteria in this zone are all the while performing a complex chemical process, turning naturally occurring mercury into methylmercury, a deadly neurotoxin.
The research showed zooplankton were not particular in what they ate and actually went on feeding frenzies that could last for several weeks. This is how the accumulated methylmercury moved on up the food chain. “This system is incredibly efficient at accumulating methylmercury,” said Schartup.
The same research was applied to the area of the reservoir to be flooded upstream in the Churchill River. Tests showed methylmercury levels could increase by 25 to 200 percent. “It would be devastating,” said David Wolfrey, a conservation officer from Rigolet, a Nunatsiavut community on the far eastern edge of Lake Melville.
The Nunatsiavut Government is lobbying Nalcor Energy, the provincial energy corporation and the Provincial and Canadian governments, asking them to mitigate the downstream effects of the hydroelectric plant. “Scientists have a responsibility to understand and explain how environmental systems will react before they are modified,” Schartup said. “Because once the damage is done, you can’t take it back.”
This study was published in the journal Proceedings of the National Academy of Sciences on Sept. 8, 2015, and is entitled: Freshwater discharges drive high levels of methylmercury in Arctic marine biota
More about arctic marine life, methylmercury, potent neurotoxins, environmental impact report, Clean energy
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