Document Detail

Analysis of trends in episodic acidification of streams in western Maryland.
MedLine Citation:
PMID:  17874761     Owner:  NLM     Status:  MEDLINE    
In this study we report on changes in the magnitude and mechanisms of episodic acidification of a small acid-sensitive stream in western Maryland (U.S.) during the 1990s, a period in which wet sulfate deposition declined by 10-25% due to implementation of the Clean Air Act Amendments (CAAA) of 1990. We observed a relatively minor trend in the magnitude of episodic acidification over this period, as measured bytransient changes in acid neutralizing capacity (deltaANC) and minimum values of ANC (ANC(min)) during 22 events sampled prior to and following CAAA implementation. Any relationship to changes in atmospheric deposition appears to be confounded by large hydroclimatological variability between the two sampling periods. Nonetheless, results obtained prior to implementation of the CAAA indicated that the mechanism of episodic acidification was mostly attributable to flushing of accumulated sulfate from the watershed, whereas results obtained post-CAAA indicated domination by base cation dilution. This shift in the mechanism of episodic acidification is qualitatively consistent with hydrochemical theory, as well as with empirical results from surface waters in other regions where dramatic declines in sulfate deposition have taken place.
Kathleen M Kline; Keith N Eshleman; Raymond P Morgan; Nancy M Castro
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Environmental science & technology     Volume:  41     ISSN:  0013-936X     ISO Abbreviation:  Environ. Sci. Technol.     Publication Date:  2007 Aug 
Date Detail:
Created Date:  2007-09-18     Completed Date:  2007-10-10     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0213155     Medline TA:  Environ Sci Technol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  5601-7     Citation Subset:  IM    
University of Maryland Center for Environmental Science, Appalachian Laboratory, 301 Braddock Road, Frostburg, Maryland 21532, USA.
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MeSH Terms
Acids / analysis*,  chemistry
Rivers / chemistry*
Sulfates / chemistry
Water Movements
Reg. No./Substance:
0/Acids; 0/Sulfates

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