Acidification sources in red alder and Douglas fir soils - importance of nitrification
Precipitation, throughfall, forest floor, and soil leachate samples were monitored continuously in 1981 and 1982 in a N-poor douglas fir (Pseudotsuga menziesii (Mirb.) Franco) forest and a red alder (Alnus rubra Bong.) forest growing adjacently on a glacial soil in western Washington. The purpose of the study was to quantify the relative importance of atmospheric vs. natural sources of H input to forest soil acidification, and to determine the role of N transformation processes in the overall H balance of soils with different N status. Rainwater samples had an avg pH of 4.7 and annual H deposition via precipitation averaged 320 mol H ha yr . This was modest compared to internal H production associated with HCO3 and NO3 formation. In the soil under alder cover, which was naturally enriched in N through symbiotic N2-fixation, nitrification released up to 4500 mol H ha annually to the solution percolating through the upper part of the soil profile. In the N-poor soil no nitrification could be observed and N transformation processes had a minor influence on the soil H balance. The main internal acidification source in this case was H2CO3 dissociation releasing 420 mol H ha yr . In both instances, soil solutions appeared well buffered against these external and internal acidification sources, and few H leached below the 40-cm soil depth.
- Research Organization:
- Univ. of Washington, Seattle
- OSTI ID:
- 6294116
- Journal Information:
- Soil Sci. Soc. Am. J.; (United States), Journal Name: Soil Sci. Soc. Am. J.; (United States) Vol. 49:5; ISSN SSSJD
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
Atmospheric-- Chemicals Monitoring & Transport-- (-1989)
510200* -- Environment
Terrestrial-- Chemicals Monitoring & Transport-- (-1989)
54 ENVIRONMENTAL SCIENCES
ACID RAIN
ACIDIFICATION
ATMOSPHERIC PRECIPITATIONS
BUFFERS
CATIONS
CHARGED PARTICLES
CHEMICAL REACTIONS
CONIFERS
DISSOLUTION
ENVIRONMENTAL EFFECTS
FEDERAL REGION X
FORESTS
HYDROGEN IONS
HYDROGEN IONS 1 PLUS
IONS
LEACHING
NATURAL OCCURRENCE
NITRIFICATION
NORTH AMERICA
PH VALUE
PLANTS
POLLUTION SOURCES
POPLARS
RAIN
SEPARATION PROCESSES
SOILS
TREES
USA
WASHINGTON