by Marco Torres
November 09, 2016
Hydroelectric power is not clean at all.
In fact, Harvard University has found that over 90 percent of
potential new hydroelectric projects will increase concentrations of
methylmercury in the food chain.
...and Canada is forecasting 22 new
hydroelectric reservoirs in the coming years.
The study (Greenhouse Gas Emissions from Reservoir Water Surfaces - A New Global Synthesis) from Washington State University finds that methane, which is at least 34 times more potent than another greenhouse gas, carbon dioxide, makes up 80% of the emissions from water storage reservoirs created by dams.
more, none of these emissions are currently included in global
greenhouse gas inventories.
production of the bio-accumulative neurotoxin methylmercury (MeHg) is
stimulated in newly flooded soils by degradation of labile organic
carbon and associated changes in geochemical conditions.
Dozens of scientific inquiries and
studies on the
adverse effects of thimerosal, including
gastrointestinal abnormalities and immune system irregularities have
clearly shown that Thimerosal-Derived Ethylmercury
in vaccines is a mitochondrial
in human brain cells.
Methylmercury subject groups confirm that the metabolic pathway for mercury in the human and animal body consists in the reduction/conversion of the harmful methylmercury into a more harmful "inorganic" mercury which is tissue-bound, and long-term-toxic.
Hence, both the originating substance (methylmercury) and its conversion/reduction, inorganic mercury are found.
Impacts of Hydroelectric Power Development on Methylmercury
Exposures of Canadian Indigenous Communities)
published in Environmental Science & Technology has probabilistically modeled
peak MeHg enrichment relative to measured baseline conditions in
rivers to be impounded, downstream estuary, locally harvested fish,
wildlife, and local communities.
Results show a projected 10-fold increase in riverine MeHg levels and a 2.6-fold increase in estuarine surface waters.
MeHg concentrations in locally caught species increase 1.3 to 10-fold depending on time spent foraging in different environments.
The most visible and immediate impact of large-scale hydropower is from the reservoir behind the dam.
There's no getting around the fact that
you're drowning vast areas of land that was habitat for animals, and
was likely a storehouse of biodiversity, sequestering decent amounts
of carbon. You've also fragmented the habitat that remains.
There are ways of mitigating this, in some cases (not so much with large dams) in regards to wildlife, but some level of disruption is assured. Downstream, the changes in water flow that result from the water passing through the turbines, even if total volume is maintained, can lead to erosion, differences in oxygen levels and water warmth affecting animal populations.
This is all hard to quantify with a
single statistic, in part because the conditions vary from project
to project, but also because there are just so many areas of the
ecosystem impacted. As you can imagine though, these sort of
problems are greater with large-scale projects that community-level
The methylmercury moves into the water
and animals, magnifying as it moves up the food chain. This makes
the toxin especially dangerous for indigenous communities living
near hydroelectric projects because they tend to have diets rich in
local fish, birds and marine life.
The project will require the flooding of land bordering the Churchill River, upstream from an estuarine fjord called Lake Melville.
Elsie Sunderland and her team have been working in this region since 2012, conducting a multi-pronged investigation into how methylmercury accumulates in the ecosystem and how it may impact communities who rely on the ecosystem for food and resources.
To build the framework, the team collected extensive measurements of how different forms of mercury cycle through this ecosystem and formalized a mathematical model to forecast post-flooding methylmercury levels in the Churchill River and downstream estuary.
They then used measurements of levels of methylmercury in the food web and unique chemical tracers for where each food item, such as salmon or trout, obtained its methylmercury to project levels of the toxin in different species of fish and wildlife.
Finally, the team studied the diets and baseline methylmercury exposures of more than 1000 Inuit who live on Lake Melville’s shore to understand how changes in their food would affect individual exposures.
The team found that while there were large differences in exposure to methylmercury across the population, on average exposure to the toxin will double after the upstream area is flooded.
While some people are still below the U.S. Environmental Protection Agency’s (EPA) reference dose for methylmercury, any increase in exposure is associated with increased risks of cardiovascular disease and neurodevelopmental delays among children
The people at the highest risk of mercury exposure are those who eat locally caught wildlife nearly every day, especially river fish, where the increase of methylmercury is expected to be highest.
Pregnant women and children are especially at risk for health impacts of methylmercury.
People are exposed to methylmercury primarily through their diet, especially through the consumption of fish and other marine species, as well as through the consumption of rice when it is grown in a methylmercury-rich environment.
It's one reason advocacy arms of consumer reporting
advise women to avoid tuna.
In adults, elevated methylmercury
exposure can lead to neurological problems, such as memory loss and
tremors. Recent studies show that methylmercury exposures
can also lead to cardiovascular and immune effects.
The team applied the prospective framework to the 22 other proposed hydroelectric sites in Canada, plugging in publically available, site-specific data.
They found that 11 sites had equal or greater methylmercury concentrations relative to Muskrat Falls.