Atmospheric sulfur deposition, neutralization, and ion leaching in two deciduous forest ecosystems

Journal Article · · J. Environ. Qual.; (United States)

OSTI ID:6827612

Richter, D D; Johnson, D W; Todd, D E

In the 1981 water year, bulk precipitation was primarily a solution of dilute H/sub 2/SO/sub 4/, and SO/sub 4//sup 2 -/ was the dominant anion in throughfall and soil leachates in two eastern Tennessee deciduous forests. Ecosystem inputs of SO/sub 4//sup 2 -/, which included dry deposition of forest canopies, may have been up to 40% greater than input estimates based on atmospheric deposition sampling in open areas. Volume-weighted mean annual pH of bulk precipitation was 4.3; of throughfall 4.8; and of leachates from O2, A1, and B21 soil horizons about 6.0. At both sites, strong acids in precipitation were largely neutralized prior to rainfall's infiltration into mineral soil. Base cations that exchanged with H/sup +/ (hydrogen ions) in acid precipitation were almost entirely supplied by forest canopies and litter layers, and did not come directly from exchangeable mineral soil pools. Inputs of H/sup +/ from acid precipitation were equal to about 0.4% of the base cations that are biologically cycling and immediately available in these ecosystems. Although poorly quantified, mineral weathering and deep rooting will supply, over time, substantial amounts of additional base cations for biologic cycling. Both soils are base-poor Udults and classified as sensitive to acid rain, but the deposition, cycling, and soil data presented in this report indicate that leaching remains a process affecting cation reserves and soil development only over the very long term.

• Research Organization: Oak Ridge National Lab., TN
• DOE Contract Number: W-7405-ENG-26
• OSTI ID: 6827612
• Journal Information: J. Environ. Qual.; (United States), Journal Name: J. Environ. Qual.; (United States) Vol. 12:2; ISSN JEVQA
• Country of Publication: United States
• Language: English

Related Subjects

500200* -- Environment
Atmospheric-- Chemicals Monitoring & Transport-- (-1989)
510200 -- Environment
Terrestrial-- Chemicals Monitoring & Transport-- (-1989)
54 ENVIRONMENTAL SCIENCES
ACID RAIN
ATMOSPHERIC PRECIPITATIONS
CATIONS
CHARGED PARTICLES
CHEMISTRY
DEPOSITION
DISSOLUTION
ECOSYSTEMS
ENVIRONMENTAL EFFECTS
FEDERAL REGION IV
FORESTS
ION EXCHANGE
IONS
LEACHING
LEAVES
NORTH AMERICA
OXYGEN COMPOUNDS
PH VALUE
RAIN
SAMPLING
SEPARATION PROCESSES
SOIL CHEMISTRY
SOILS
SULFATES
SULFUR COMPOUNDS
TENNESSEE
TERRESTRIAL ECOSYSTEMS
USA