Coal ash selenium found in fish in N.C. lakes

February 7, 2017, Duke University
A coal-fired power plant on Sutton Lake, N.C. Fish in this lake and others that receive coal-ash effluents have been found to contain higher levels of the contaminant selenium. Credit: Jessica Brandt, Duke University

A new Duke University study has found high levels of selenium in fish in three North Carolina lakes receiving power plants' coal ash waste.

"Across the board, we're seeing elevated selenium levels in from lakes affected by coal combustion residual effluents," said Jessica Brandt, a doctoral student in environmental health at Duke's Nicholas School of the Environment, who led the study.

Selenium is a naturally occurring element that is concentrated in and other coal combustion residuals. Early life exposure can cause deformities, impaired growth and reproduction, and in extreme cases death in fish and aquatic invertebrates. Because selenium accumulates in the food chain, it also can be toxic to birds that eat aquatic animals containing high levels.

Brandt and her colleagues published their peer-reviewed study Feb. 6 in the journal Environmental Science & Technology.

They measured selenium levels in surface water, bottom-sediment waters and fish from three N.C. lakes—Sutton Lake near Wilmington, Mayo Lake near Roxboro, and Mountain Island Lake near Charlotte. The three lakes are, or until recently were, discharge sites for effluents from coal-fired power plants. Four types of fish tissue were analyzed: liver, muscle, ovary and testes.

The team also measured selenium in water, sediment and fish tissues in three similar lakes—Adger, Tillery and Waccamaw—with no such history of contamination. Samples were collected over a three-month period in spring 2015.

"Catastrophic releases of coal ash like the Dan River spill of 2014 get all of the attention, but there is ongoing, continuous contamination of aquatic ecosystems from hundreds of coal ash ponds across the country," Brandt said. "People fish in these lakes for recreation and subsistence purposes. We want to protect these public resources."

The EPA recently revised its selenium threshold criteria for aquatic health, and now places greater weight on concentrations in tissue rather than in water for evaluating ecosystem impacts.

"Selenium concentrations in surface water don't tell us as much about the risk of exposure to fish," Brandt explained.

Of the three coal ash discharge lakes tested in the new study, Sutton Lake had the highest levels of selenium. Eighty-five percent of all fish muscle samples examined there contained selenium levels above the EPA's threshold.

In Mayo Lake, 27 percent of muscle samples exceeded the EPA criteria.

Levels were below the EPA criteria in Mountain Island Lake.

North Carolina has new coal ash management rules in place to close coal ash ponds at some , Brandt noted. "But it will be important to continue monitoring sediments and fish tissues at these sites after the inputs are stopped," she said. "You have to look beneath the surface to understand how these problems persist over time."

The new study did not evaluate potential human health risks posed by the coal ash residual contamination.

Explore further: Coal ash ponds found to leak toxic materials

More information: Jessica E. Brandt et al, Selenium Ecotoxicology in Freshwater Lakes Receiving Coal Combustion Residual Effluents: A North Carolina Example, Environmental Science & Technology (2017). DOI: 10.1021/acs.est.6b05353

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8 comments

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24volts
not rated yet Feb 07, 2017
I don't know about the other two but Sutton lake was used only for cooling water for the steam condensers on the turbines.
pinguino
1 / 5 (2) Feb 07, 2017
Everything I have read before this indicated that not only is selenium not dangerous, it can protect against free radicals and extend life. It is routinely added to dietary supplements and multi-vitamin formulas. So why is it now being called dangerous?
Jeffhans1
5 / 5 (3) Feb 07, 2017
Everything I have read before this indicated that not only is selenium not dangerous, it can protect against free radicals and extend life. It is routinely added to dietary supplements and multi-vitamin formulas. So why is it now being called dangerous?


According to Wikipedia:
Although it is toxic in large doses, selenium is an essential micronutrient for animals. In plants, it occurs as a bystander mineral, sometimes in toxic proportions in forage (some plants may accumulate selenium as a defense against being eaten by animals, but other plants, such as locoweed, require selenium, and their growth indicates the presence of selenium in soil)

So in other words, like many things, you need a little bit, but too much will kill you.
gkam
3.5 / 5 (8) Feb 07, 2017
pinguino,most things are safe in low doses. Look up Kesterson Wildlife Refuge to see what Selenium does.
howhot3
5 / 5 (8) Feb 07, 2017
I hate to point to the obvious, but this is just another add-on to why we need to remove coal from the electric grid.
Whydening Gyre
5 / 5 (8) Feb 07, 2017
So in other words, like many things, you need a little bit, but too much will kill you.

As in all things - moderation...
Whydening Gyre
5 / 5 (6) Feb 08, 2017
I don't know about the other two but Sutton lake was used only for cooling water for the steam condensers on the turbines.

Even the simple modification of heat can effect the concentration and solubility of differing elements within water...
Captain Stumpy
4.6 / 5 (9) Feb 08, 2017
Everything I have read before this indicated that not only is selenium not dangerous, it can protect against free radicals and extend life. It is routinely added to dietary supplements and multi-vitamin formulas. So why is it now being called dangerous?
@pinguino
first off, as Jeffhans1 stated, read the wiki page: https://en.wikipe...Selenium

pay special attention to the label: toxicity
https://en.wikipe...Selenium#Toxicity

for a better understanding of it that may be easier for you to understand, consider Iodine
(when taken orally, elemental iodine is toxic) https://en.wikipe...Toxicity

but we need iodine to live, so it is a required nutrient
https://en.wikipe...cal_role

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