Legacy of Coal Combustion: Widespread Contamination of Lake Sediments and Implications for Chronic Risks to Aquatic Ecosystems

Elevated
concentrations of toxic elements in coal ash pose human
and ecological health risks upon release to the environment. Despite
wide public concerns about water quality and human health risks from
catastrophic coal ash spills and chronic leaking of coal ash ponds,
coal ash disposal has only been partially regulated, and its impacts
on aquatic sediment quality and ecological health have been overlooked.
Here, we present a multiproxy approach of morphologic, magnetic, geochemical,
and Sr isotopic analyses, revealing unmonitored coal ash releases
over the past 40 to 70 years preserved in the sediment records of
five freshwater lakes adjacent to coal-fired power plants across North
Carolina. We detected significant sediment contamination and potential
chronic ecological risks posed by the occurrence of hundreds of thousands
of tons of coal ash solids mainly resulting from high-magnitude stormwater
runoff/flooding and direct effluent discharge from coal ash disposal
sites. The proximity of hundreds of disposal sites to natural waterways
across the U.S. implies that such contamination is likely prevalent
nationwide and expected to worsen with climate change.