Coal ash, a common and unregulated byproduct of coal-fired power plants, has been found to contain high levels of radioactive contaminants, placing at great risk the countless number of people who live near such dumps—including the thousands of North Carolina residents affected by the 2014 Dan River spill.
The study, led by scientists with Duke University and published in the September 2 edition of Environmental Science and Technology, found that "levels of radioactivity in the ash were up to five times higher than in normal soil, and up to 10 times higher than in the parent coal itself because of the way combustion concentrates radioactivity."
Researchers said their discovery raises concerns because coal ash, also known as fly ash, disposal sites are not yet regulated, nor are they monitored for radioactivity. "We don’t know how much of these contaminants are released to the environment, and how they might affect human health in areas where coal ash ponds and landfills are leaking," said Avner Vengosh, professor of geochemistry and water quality at Duke’s Nicholas School of the Environment.
According to the study, when coal is burned, naturally occurring radium isotopes "become concentrated in the coal ash residues, and the lead-210 becomes chemically volatile and reattaches itself to tiny particles of fly ash. This causes additional enrichment of radioactivity in the fly ash."
Vengosh noted that potentially airborne contaminants are less of a concern, because smokestack scrubbers keep them from escaping. However, if the contaminated byproduct is spilled or leaked from a holding pond, it may pose a hazard.
In February 2014, roughly 82,000 tons of toxic coal ash spilled from broken pipe leading from a holding pond owned by the nation's largest electricity company, Duke Energy, into North Carolina's Dan River. In that state alone, Duke currently stores more than 150 million tons of coal ash in 32 dumps at 14 power plants. However, such disposal sites are found near coal-fired power plants worldwide.
The study is the first comprehensive review of coal ash from all three major U.S. coal ash producing basins: the Illinois, Appalachian, and Powder River, which is in Wyoming and Montana. Ash in the Illinois basin was found to contain the highest levels of radioactivity.
The U.S. Environmental Protection Agency has passed a new set of rules regulating the disposal of coal ash, set to take effect in October.