Poison in Arctic and human cost of ‘clean’ energy [View all]

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http://news.harvard.edu/gazette/story/2015/09/poison-in-arctic-and-human-cost-of-clean-energy/

[font face=Serif][font size=5]Poison in Arctic and human cost of ‘clean’ energy[/font]

[font size=4]Hydroelectric energy may be more damaging to northern ecosystems than climate change[/font]

September 7, 2015

By Leah Burrows, Harvard Paulson School Communications

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The amount of methylmercury, a potent neurotoxin, is especially high in Arctic marine life but until recently, scientists haven’t been able to explain why. Now, research from the Harvard John A. Paulson School of Engineering and Applied Science (SEAS) and Harvard T.H. Chan School of Public Health suggests that high levels of methylmercury in Arctic life are a byproduct of global warming and the melting of sea-ice in Arctic and sub-Arctic regions.

To mitigate global warming, many governments are turning to hydroelectric power. But, the research also suggests that methylmercury concentrations from flooding for hydroelectric development will be far greater than those expected from climate change.

The research, published in PNAS, began as a review of the environmental impact assessment for the Muskrat Falls hydroelectric dam in Labrador, Canada. In 2017, the dam will flood a large region upstream from an estuarine fjord called Lake Melville.

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When fresh and salt water meet— in estuaries or when sea ice melts in the ocean— salinity increases as water deepens. This stratification allows fluffy organic matter that typically sinks to the bottom to reach a neutral buoyancy — meaning it can’t float up or down in the water column. This layer, called marine snow, collects other small settling debris and concentrates it into a feeding zone for marine plankton. The bacteria stuck in this zone are performing a complex chemical process that turns naturally occurring mercury into deadly and readily accumulated methylmercury.

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