By Katie Demeria
Shenandoah Valley streams have seen a slower recovery from the damage of acid rain than those in the northeastern parts of the country. The explanation goes back 15,000 years.
Acid rain and its impact on the environment became a big issue in the 1980s and 90s, when studies were conducted to analyze how much acid deposition was collecting in streams and soil due to emissions in the air.
The Environmental Protection Agency worked to reduce those emissions, according to Holly Salazar, regional air resource coordinator with the National Parks Service. Those policies, such as the Clean Air Act, have largely reduced acid depositions.
"When we talk about air quality in Shenandoah, we have to talk about water, we talk about air, we talk about soils, we talk about plants, we talk about visibility -- air quality affects a lot of different things," Salazar said.
According to the Virginia Trout Stream Sensitivity Study, 2010 survey, conducted through the University of Virginia, "sulfur dioxide emissions from coal-fired power plants declined by 64 percent" between 1990 and 2009.
Many areas saw rapid improvements after those reductions. The Adirondack region in New York, for example, has seen significant improvements to the health of its ecosystems and forests, according to Salazar.
"But it's different in the southern portion of our region," she added.
Amy Riscassi, project coordinator for the Shenandoah watershed study at the University of Virginia, said a difference in the soils has a huge impact on how recovery takes place.
"The last glaciation did not reach us down here in this Appalachian region, it stopped somewhere in Pennsylvania," Riscassi said. "That had an effect on the soils."
The glaciers, Riscassi explained, scraped the older soil in the north until it was replaced with something newer 10,000 to 15,000 years ago. But without that process in the southern region, soil is much older and weathered, impacting its ability to absorb acid inputs from acid rain.
Because of that older soil, she continued, recovery is lagging. It retains acid better than new soil, so acid is still leaking into the waters and impacting streams even though emissions have decreased.
It is as though some Shenandoah streams are seeing the damage of acid rain slowly, so the nearby ecosystems must deal with that added acidification over a longer period of time.
Jalyn Cummings, air and water program manager with Shenandoah National Park, said the park is working hard to aid the ecosystem as the acid works itself out of the system. Most of the recovery, though, must take place naturally.
"And that could take decades in some of our watersheds, and it could take hundreds of years in some others," Cummings said.
The impact on the ecosystem, and especially fish, is a big question. According to Riscassi and Cummings, staying ahead on the research will help them find possible ways to mitigate the damage to those sensitive organisms.
Not only do episodic acidification events, which take place when acid leaks from the soil and enters the water, impact the water's ph level, it also changes the temperature, which can hurt sensitive fish.
Ensuring that no further harmful emissions increase the acid depositions is one of the most important things the general public can do to help the streams heal, according to Riscassi and Cummings.
"It's important to get out our story, and have our visitors and general public understand what it's going to take to let these watersheds heal from decades of acid deposition," Cummings said. "Nature takes time to heal."
Contact staff writer Katie Demeria at 540-465-5137 ext. 155, or firstname.lastname@example.org