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Acid-rain induced changes in streamwater quality during storms on Catoctin Mountain, Maryland

Open-File Report 92-649

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Abstract

Catoctin Mountain receives some of the most acidic (lowest pH) rain in the United States. In 1990, the U.S. Geological Survey (USGS), in cooperation with the Maryland Department of the Environment (MDE) and the Maryland Department of Natural Resources (DNR), began a study of the effects of acid rain on the quality of streamwater on the part of Catoctin Mountain within Cunningham Falls State Park, Maryland (fig. 1). Samples of precipitation collected on the mountain by the USGS since 1982 have been analyzed for acidity and concentration of chemical constituents. During 1982-91, the volume-weighted average pH of precipitation was 4.2. (Volume weighting corrects for the effect of acids being washed out of the atmosphere at the beginning of rainfall). The pH value is measured on a logarithmic scale, which means that for each whole number change, the acidity changes by a factor of 10. Thus rain with a pH of 4.2 is more than 10 times as acidic as uncontaminated rain, which has a pH of about 5.6. The acidity of rain during several rainstorms on Catoctin Mountain was more than 100 times more acidic than uncontaminated rain.

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Additional publication details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Acid-rain induced changes in streamwater quality during storms on Catoctin Mountain, Maryland
Series title:
Open-File Report
Series number:
92-649
Year Published:
1992
Language:
English
Publisher:
U.S. Geological Survey
Publisher location:
Towson, MD
Contributing office(s):
Virginia Water Science Center
Description:
2 p.
Country:
United States
State:
Maryland
County:
Frederick
Other Geospatial:
Catoctin Mountain