Potential for buffering of acidic precipitation by mineral weathering in a forested entisol

Journal Article · · Soil Sci. Soc. Am. J.; (United States)

OSTI ID:6248116

Li, C S; Bockheim, J G; Leide, J E; Wentz, D A

Bulk precipitation, soil-water, and groundwater chemistry were monitored at Round Lake, a small, forested catchment receiving acidic precipitation (pH 4.6) in northwestern Wisconsin. The groundwater basin retained H ion and released nonhydrolyzable cations (NHC = Ca, Mg, Na, K) and Si. The percentages of plagioclase feldspar, hornblende, olivine, and augite increased with depth in soils from the catchment; quartz, orthoclase feldspar, and weathered mica decreased with depth. Thermodynamic stability indices estimated from water-quality and mineralogic data, and from the WATEQF chemical speciation model indicate that the soil-water and groundwater are undersaturated with respect to hornblende, chlorite, olivine, augite, plagioclase, and orthoclase feldspars and that these minerals may be undergoing dissolution. Minimally disturbed soil cores were leached with dilute H/sub 2/SO/sub 4/ and distilled water. When the pH of the extracting solution was greater than or equal to 4.5, Ca was released in the greatest amounts, followed by Si, Mg, K, Na, and Al. This ranking is similar to that for cations in groundwater. Leaching with a pH 3.0 solution released Si in the greatest amounts from the C horizon, followed by the Bw2, Bw1, and A + B/E horizons. This trend parallels the depth distribution of weatherable minerals in the very fine sand fraction. Results from the laboratory leaching study confirm the chemical modeling studies, indicating that mineral weathering can contribute to buffering within the groundwater basin at Round Lake.

• Research Organization: Univ. of Wisconsin, Madison (USA)
• OSTI ID: 6248116
• Journal Information: Soil Sci. Soc. Am. J.; (United States), Journal Name: Soil Sci. Soc. Am. J.; (United States) Vol. 52:4; ISSN SSSJD
• Country of Publication: United States
• Language: English

Related Subjects

510200* -- Environment
Terrestrial-- Chemicals Monitoring & Transport-- (-1989)
520200 -- Environment
Aquatic-- Chemicals Monitoring & Transport-- (-1989)
54 ENVIRONMENTAL SCIENCES
ACID NEUTRALIZING CAPACITY
ACID RAIN
ALKALI METALS
ALKALINE EARTH METALS
ALUMINIUM
ATMOSPHERIC PRECIPITATIONS
BUFFERS
CALCIUM
CHEMISTRY
DISSOLUTION
ELEMENTS
ENVIRONMENTAL EFFECTS
ENVIRONMENTAL QUALITY
FEDERAL REGION V
FORESTS
GROUND WATER
HYDROGEN COMPOUNDS
ION EXCHANGE
LAKES
MAGNESIUM
METALS
MINERALS
NORTH AMERICA
OXYGEN COMPOUNDS
PH VALUE
POTASSIUM
RAIN
SEMIMETALS
SILICON
SODIUM
SURFACE WATERS
THERMODYNAMICS
USA
WATER
WATER CHEMISTRY
WATER QUALITY
WEATHERING
WISCONSIN