Toxic coal ash leaching from lakes into the food chain

An analysis of fresh water sources in one US state has revealed a markedly wider and more persistent problem than thought. 

Toxic coal ash that has found its way from the air into lake bottom sediment is at a much greater risk of leaching into the food chain unchecked than previously understood, according to new research by Duke University. 

Focusing on five North Carolina lakes situated near coal power plants, the study has identified a significantly higher risk that ash deposited on surface water before making its way to the bed has the significant potential to spread toxins which then enter the aquatic food chain. 

While it has long been understood coal burning releases particles into the air which then return to Earth as ash, and this can settle on lakes, this latest investigation suggests the extent to which that happens has been grossly underestimated. The bottom sediment of any lake represents the complete historic record of everything that has fallen into it, so focusing on this gives a more accurate picture of how much coal has wound up in the water overall. 

‘Using our age-dating methods, we were able to go back in time, in some cases even before the coal plant was built, and reconstruct the history of the lakes,’ said Avner Vengosh, a Duke University Distinguished Professor of Environmental Quality at the Nicholas School of the Environment, who made clear the contaminants, which can be carcinogenic, are not locked into the sediment and there is clear evidence of leaching into the water, where it can be consumed by fish and other animals in the lake.

‘These are recreational lakes,’ said Zhen Wang, a PhD student at Duke Nicholas School of the Environment and the lead author of the study. ‘Some of them, like Hyco Lake, were originally built for the coal plant, but over the years, it has become very desirable real estate where people build their dream homes. It looks very pristine and beautiful, but if you dig in, you find piles of toxic coal ash.’

You can read the full Duke University study here. Earlier this week, Air Quality News reported on Northern Ireland’s Environment Minister ruling out a new ban on the sale and use of smoky coal in a blow to environmentalists. 

Image: Zoltan Tasi