Sequential sampling and analysis of precipitation in the Shenandoah Valley

Abstract

This research reports the establishment and operation of a developmental sequential rain sampler in the Shenandoah Valley. It also reports the results obtained from the rainwater analysis precipitation at and this the determination rural site is of whether the acidic or not. Rainwater collection was conducted sequentially and on an event basis from October 1982 to January 1983. Trajectory analysis was performed for each individual rain event to determine the probable source and path of the air mass that is precipitated. Continental type events, as compared to maritime events, were the predominant rain events in the Shenandoah Valley over the study period. The rainwater at the site proved to be slightly acidic with a volume weighted average pH of 5.05 and a pH range of 4.68 to 6.21. The sequential collection of the rainwater and its analysis indicated no definite pH trend within individual events. Most element concentrations tended to decrease or remain at a constant level as the rain event progressed. The sulfate ion was the predominant acid anion during the study period. Elevated ionic centrations alone within the rainwater, specifically sulfate and nitrate, did not correlate with rainwater acidity.