Several North Carolina lakes and rivers contain high levels of toxic compounds, a recent Duke study shows.
Researchers at the Nicholas School discovered that coal ash residue from coal-fired power plants contributes to high arsenic and selenium concentrations, among other toxic chemicals, in lakes and rivers. Coal ash effluents flow downstream from the power plants’ settling ponds to affect water sources. Researchers gathered more than 300 water samples from 11 lakes and rivers over an 18-month span. The contaminated sites include the Mountain Island Lake, which is a primary water source for residents in Charlotte. Several other sites also contain high levels of chemicals that exceed the Environmental Protection Agency’s guidelines for safe drinking water.
The findings of the study may prompt greater regulation and monitoring of coal ash effluents, said Avner Vengosh, professor of geochemistry and water quality at the Nicholas School and co-author of the study.
“What we found in North Carolina is a case study of the effects of coal ash in the United States—we want to see if any regulation arises from this data,” Vengosh said.
According to the study, approximately 600 U.S. power plants generate 130 million tons of coal ash residue annually, making it one of the largest industrial waste products in the country. But there is still little monitoring on coal ash residue since most regulatory measures—such as the Clean Air Act—have focused on reducing power plants’ emissions into the air, Vengosh noted.
The Clean Air Act is a federal law designed to control air pollution on a national level to protect the general public from exposure to airborne contaminants.
“The real issue is that there is no regulation of coal ash in the United States, and factories are not doing anything about it either,” Vengosh said. “We are saving the sky, but we are making the contamination in the water more severe.”
The breadth of the data allowed closer analysis of the effects of coal ash, said Heileen Hsu-Kim, assistant professor of civil and environmental engineering and co-author of the study. Samples were collected monthly from the Hyco and Mayo lakes for a year, which gave a sense of temporal variability in the chemical concentrations in the water.
High contaminant levels pose more of an ecological health concern, rather than a human health concern, Kim said. There are certain physiological changes that can arise in various fish organisms, such as deformation of the spine and effects on reproductive capabilities. The contaminants may cause subtle changes that change the makeup of the lake or river.
Vengosh has started working on a new project to find the source of the contaminants in the water.
“We are using isotope fingerprints to build the ‘smoking gun’ and to see the source of the contamination.” Vengosh said. “For example, if there is someone who says the contamination is coming from a different source, we can confirm it.”
Laura Ruhl, lead author of the study and assistant professor at the University of Arkansas at Little Rock, could not be reached for comment. The study was funded by the North Carolina Water Resources Research Institute.
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