Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Poison in the Arctic and the human cost of 'clean' energy


Hydroelectric energy may be more damaging to northern ecosystems than climate change

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.

Rigolet is on the shore of Lake Melville.

Credit: Prentiss Balcom

To mitigate global warming, many governments are turning to hydroelectric power but the research also suggests that flooding for hydroelectric development will put even more methylmercury into ecosystems than 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, which, in 2017, will flood a large region upstream from an estuarine fjord called Lake Melville. The majority of the lake lies in Nunatsiavut, the first autonomous region in Canada governed by Inuit. The predominantly indigenous communities along Lake Melville rely on the lake as a primary source of food.

When an impact report predicted no adverse downstream effects into Lake Melville from the flooding, the Nunatsiavut Government reached out to Elsie Sunderland, associate professor of environmental engineering at SEAS and environmental health at the Harvard Chan School, for help.

"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."

Sunderland and her team -- including lab manager Prentiss Balcom and postdoctoral fellow Amina Schartup, the paper's first author -- made their first trip to Lake Melville in 2012. They collected baseline methylmercury levels on a fishing boat called "What's Happening" -- which was exactly the question Sunderland and her team asked when the results came in.

"We found more methylmercury in the water than our modeling could explain," said Schartup. "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."

The team noted that the concentration of methylmercury in biota -- the plankton --peaked between 1 and 10 meters below the surface.

These findings closely matched findings from the central Arctic Ocean. The question was, why was there such a high concentration of methylmercury in biota in both systems?

The answer lay in the eating habits of plankton.

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.

Attracted to this layer of marine snow, the zooplankton go on a feeding frenzy that can last several weeks. In this time, methylmercury produced by the bacteria accumulates in biota and magnifies as it works its way up the food chain.

"This system is incredibly efficient at accumulating methylmercury," said Schartup.

This same system can be extrapolated to the Arctic, where freshwater from melting ice is mixing with salt water, Schartup said.

If this system is already a pro at magnifying methylmercury, what happens when methylmercury levels increase due to reservoir flooding upstream?

Sunderland and her team collected soil cores from the inland areas that are slated to be flooded for hydroelectric power in 2017. The team simulated flooding by covering the cores with river water. Within five days, methylmercury levels in the water covering the cores increased 14 fold. Estimated increases in methylmercury inputs from the Churchill River resulting from this pulse of methylmercury range from 25 to 200 percent.

That's the low estimate.

"We removed the litter layer and surface vegetation prior to saturating the cores, which is known to decrease methylmercury levels, " Sunderland said. "Without clearing that, the actual pulse of methlymercury to the Lake Melville ecosystem may be much greater."

For communities who rely on the ecosystem for food, like those along Lake Melville, the downstream effects of flooding for hydroelectric development could be devastating.

"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."

Leah Burrows | EurekAlert!

More articles from Earth Sciences:

nachricht UCI and NASA document accelerated glacier melting in West Antarctica
26.10.2016 | University of California - Irvine

nachricht Ice shelf vibrations cause unusual waves in Antarctic atmosphere
25.10.2016 | American Geophysical Union

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Etching Microstructures with Lasers

Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.

This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...

Im Focus: Light-driven atomic rotations excite magnetic waves

Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion

Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

How nanoscience will improve our health and lives in the coming years

27.10.2016 | Materials Sciences

OU-led team discovers rare, newborn tri-star system using ALMA

27.10.2016 | Physics and Astronomy

'Neighbor maps' reveal the genome's 3-D shape

27.10.2016 | Life Sciences

More VideoLinks >>>