Record Display for the EPA National Library Catalog


OLS Field Name OLS Field Data
Main Title Mechanisms of Episodic Acidification in Low-Order Streams in Maine, USA.
Author Kahl, J. S. ; Norton, S. A. ; Haines, T. A. ; Rochette, E. A. ; Heath, R. H. ;
CORP Author National Park Service Cooperative Park Studies Unit, Knoxville, TN. ;Maine Univ. at Orono. ;Washington State Univ., Pullman. Dept. of Agronomy and Soils.;Corvallis Environmental Research Lab., OR.
Publisher c1992
Year Published 1992
Report Number EPA/600/J-92/399;
Stock Number PB93-121283
Additional Subjects Maine ; Streams ; Acidification ; Water pollution ; Water chemistry ; pH value ; Surface waters ; Air water interactions ; Air pollution ; Acid neutralizing capacity ; Saline water-freshwater interfaces ; Sulfur oxides ; Nitrogen oxides ; Coastal regions ; Salt balance ; Precipitation(Meteorology) ; Toxic substances ; Soils ; Deposition ; Reprints ; Episodic depressions
Library Call Number Additional Info Location Last
NTIS  PB93-121283 Most EPA libraries have a fiche copy filed under the call number shown. Check with individual libraries about paper copy. 06/08/1993
Collation 10p
In addition to decreases in base cations associated with increased discharge, four other factors contribute to episodic depressions in pH and acid neutralizing capacity (ANC) in low-order streams in Maine: (1) increases in NO3 concentrations; (2) increases in organic acidity; (3) increases in anion fraction of SO4 concentrations; and (4) salt-effect generated acidity from soil solutions. In conjunction with increased discharge, factors 1, 2, or 4 appear necessary to depress pH to less than 5. The chemistry of individual precipitation events is irrelevant to the generation of acidic episodes, except those caused by high loading of neutral salts in coastal regions. Increases in discharge, but not necessarily in dilution of solutes, in combination with the chronically high SO4 from atmospheric deposition, provide the antecedent chemical conditions for episodic acidification. Differences in antecedent moisture conditions determine the processes that control output of either ANC or acidifying agents to aquatic systems.