EFFECTS OF ATMOSPHERIC ACID REDUCTION ON WATER CHEMISTRY OF THREE VIRGINIA TROUT STREAMS

Acid deposition from fossil fuel combustion has adversely affected streams in North America for more than four decades by emitting SOx and NOx gases into the atmosphere that go through free radical reactions and form sulfuric and nitric acid present in precipitation that falls into the streams. The acidification of streams causes the pH and ANC (acid neutralizing capacity) to fall, which leads to fauna and flora mortality. In order to address this, the U. S. Congress passed the Clean Air Act to reduce power plant emissions. SOx and NOx gases have been reduced by 76% and 68%, respectively between 1990 and 2015. We have intensively collected water chemistry data on three acid sensitive streams in the George Washington National Forest: Little Stony Creek, Mill Creek, and Mountain Run monthly since 1987. The purpose of this project is to ascertain if the reductions in acid deposition are being realized with a positive response within the streams. Little Stony shows a 25% reduction in sulfate with a corresponding decrease in hydronium ion of 58% (4.07 µeq/L to 1.70 µeq/L) and an ANC increase of 400% (-2.0 µeq/L to 6.0 µeq/L). Mill Creek there is a 26% reduction in sulfate with a corresponding decrease in hydronium ion of 52% (14.45 µeq/L to 6.92 µeq/L) and an ANC increase of 54% (-14.2 µeq/L to -6.6 µeq/L). Mountain Run has a 39% reduction in sulfate and a corresponding decrease of hydronium ion of 17% (26.92 µeq/L to 22.39 µeq/L) and 20% (-33.7 µeq/L to -27.0 µeq/L). All three streams show a positive response to the reductions in atmospheric acid but have not yet returned to pre-industrial age values.

Additional Abstract Information

Student(s): Kevin Pyszka

Department: Chemistry and Biochemistry

Faculty Advisor: Dr. Daniel Downey

Type: Oral

Year: 2017