UNIVERSITY PARK, Pa. — As Penn State researchers stood on the banks of Scalp Level Run, an acid mine drainage (AMD)-polluted stream in Cambria County, a scientific question formed: How is nature removing toxic metals from the drainage at a rate faster than any other tested waters in the state, under pH conditions deemed too low to do so?
For decades, cleanup efforts have involved raising the pH of AMD before using chemical oxidation to remove iron and other metals. And yet, at Scalp Level Run, the pollutants were being removed at a pH of around 3, and importantly, before entering the stream.
“We initially started this work because of an observation that was intriguing,” said Jennifer Macalady, associate professor of geosciences. “Some of these natural spring sites do a really good job of removing iron so that heavy metals can be treated more effectively, and that’s great because those metals are very toxic. Some AMD treatment methods are not effective because iron coats the treatment bed. Based on observations at Scalp Level Run, we wanted to see if there was a microbial component that was helping facilitate the removal of iron.”
The initial research that began nearly a decade ago sparked an interdisciplinary effort to better understand the important role microbiology plays in mitigating AMD, Pennsylvania’s largest non-point source water pollutant, impacting 2,500 miles of streams, according to the Department of Environmental Protection (DEP).