pH buffering in forest soil organic horizons: relevance to acid precipitation

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

DOI:https://doi.org/10.2134/jeq1986.00472425001500030005x· OSTI ID:7026120

James, B R; Riha, S J

Samples of organic surface horizons (Oi, Oe, Oa) from New York State forest soils were equilibrated with 0 to 20 cmol HNO/sub 3/ kg/sup -1/ soil in the laboratory by a batch technique designed to simulate reactions of acid precipitation with forest floors. Each organic horizon retained a constant percentage of added H/sup +/ (67-96%) regardless of quantity added, and buffer capacities of the samples ranged from 18 to 36 cmol (H/sup +/)kg/sup -1/(pH unit)/sup -1/, an order of magnitude higher than those measured in underlying mineral horizons. Calcium was the dominant cation in unacidified equilibrium solutions, and its concentration changed the most in response to acidification of the soils. Aluminum contributed <1% to total cationic charge in solution and Fe concentration decreased upon addition of up to at least 5 cmol (H/sup +/) kg/sup -1/. From 38 to 70% of H/sup +/ removed by the soils was not balanced by increases in soluble Ca, Mg, K, Mn, Fe, Zn, Al, and Cu, and buffering by soluble organic and inorganic constituents accounted for 8 to 58% of H/sup +/ removal. Protonation of anions of weak organic acids in solution and solid phases probably accounted for this H/sup +/ removal without increasing cation concentrations. Because of H/sup +/ removal by forest floor organic horizons and the dominance of Ca in equilibrium solutions, potential impacts of acid precipitation on aluminum solubility of underlying mineral horizons of forest soils will be due more to Ca(NO/sub 3/)/sub 2/ and CaSO/sub 4/ in leaching water, rather than to direct effects of HNO/sub 3/ and H/sub 2/SO/sub 4/.

• Research Organization: Cornell Univ., Ithaca, NY
• OSTI ID: 7026120
• Journal Information: J. Environ. Qual.; (United States), Journal Name: J. Environ. Qual.; (United States) Vol. 15:3; ISSN JEVQA
• Country of Publication: United States
• Language: English

Related Subjects

510200* -- Environment
Terrestrial-- Chemicals Monitoring &amp; Transport-- (-1989)
54 ENVIRONMENTAL SCIENCES
ACID RAIN
ACIDIFICATION
ALKALI METALS
ALKALINE EARTH METAL COMPOUNDS
ALKALINE EARTH METALS
ALUMINIUM
ANIONS
ATMOSPHERIC PRECIPITATIONS
BENCH-SCALE EXPERIMENTS
CALCIUM COMPOUNDS
CATIONS
CHARGED PARTICLES
COPPER
DATA
ELEMENTS
ENVIRONMENTAL EFFECTS
EXPERIMENTAL DATA
FEDERAL REGION II
FORESTS
HYDROGEN
HYDROGEN COMPOUNDS
HYDROGEN IONS
INFORMATION
INORGANIC ACIDS
IONS
IRON
MAGNESIUM
MANGANESE
METALS
NEW YORK
NITRATES
NITRIC ACID
NITROGEN COMPOUNDS
NONMETALS
NORTH AMERICA
NUMERICAL DATA
ORGANIC ACIDS
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
PH VALUE
POTASSIUM
RAIN
REMOVAL
SOILS
SULFATES
SULFUR COMPOUNDS
TRANSITION ELEMENTS
USA
ZINC