Chemical Composition of Precipitation and Watershed Samples Collected at Deep Creek Lake, Garrett County, Maryland - Final Report

摘要

The objective of the four-year study was to determine if acid deposition and acid stream drainage pose a significant threat to Deep Creek Lake, Maryland. The chemical composition of rain in the fourth year did not vary significantly from previous years. The annual volume-weighted mean pH of rain at the site is 3.9 - 4.0. Concentrations of hydrogen and sulfate ions are higher in summer rain, particularly for storms characterized by northwesterly winds. Summertime rain produces about 60 percent of the annual sulfate and hydrogen ion deposition at the site. The average lake water pH has remained stable during the four-year study. Acid input from Cherry Creek, impacted by geological acids, was about equal to the acid deposited directly on the lake surface by rain. During most of the year neutralization of geologic acid drainage by the bottom sediments of Cherry Creek Cove is rapid. A USGS investigation of the geology in the area found extensive alkaline rock outcroppings in the basin and underlaying the lake. It appears that concerns about rapid acidification of the lake are not well founded.