Mechanisms of episodic acidification in low-order streams in Maine, USA

Technical Report · Wed Jan 01 04:00:00 EST 1992

OSTI ID:6821791

Kahl, J S; Norton, S A; Haines, T A; Rochette, E A; Heath, R H

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 NO[sub 3] concentrations; (2) increases in organic acidity; (3) increases in anion fraction of SO[sub 4] 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.

• Research Organization: National Park Service, Knoxville, TN (United States). Cooperative Park Studies Unit
• OSTI ID: 6821791
• Report Number(s): PB-93-121283/XAB
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540320* -- Environment
Aquatic-- Chemicals Monitoring & Transport-- (1990-)
ACID NEUTRALIZING CAPACITY
ACIDIFICATION
AIR POLLUTION
CATIONS
CHALCOGENIDES
CHARGED PARTICLES
CHEMISTRY
COASTAL REGIONS
DEPOSITION
DEVELOPED COUNTRIES
DILUTION
IONS
MAINE
NITROGEN COMPOUNDS
NITROGEN OXIDES
NORTH AMERICA
OXIDES
OXYGEN COMPOUNDS
PH VALUE
POLLUTION
SOILS
SOLUTES
STREAMS
SULFUR COMPOUNDS
SULFUR OXIDES
SURFACE WATERS
USA
WATER CHEMISTRY
WATER POLLUTION