Comparative study of inorganic and organic components of soil formation in two watersheds of Alabama

Conference · Mon Mar 01 00:00:00 EST 1993 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:6078503

Kornegay, C; Donahoe, R ^[1]

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1. Univ. of Alabama, Tuscaloosa, AL (United States). Dept. of Geology

Geochemical mass balances of two forested stream ecosystems in AL (Collier Creek watershed (CCw) and Choccolocco Creek watershed (ChC)) were calculated to evaluate soil formation as a solute source for stream water chemistry. For each watershed, X-ray diffraction (XRD) analyses of soil sampled to 48 inches of depth were compared to the XRD analyses of the weathered and unweathered rock samples collected along and within the stream channel to qualitatively determine the weathering products and possible weathering reactions. Petrographic and SEM data provided verification. Exact chemical compositions of the primary and secondary minerals were determined by electron microprobe analysis. Similar mineral species were identified in the rock samples of both watersheds. The dominant clay mineral species in the rock samples of both watersheds was kaolinite. The major source of calcium and additional source of bicarbonate in streamwater appears to be from the dissolution of calcite. Iron released by the weathering of chlorite and phengite is oxidized to form hematite and/or goethite in the weathered rock samples and at depths of two to three feet in the soil of both watersheds, explaining the deficiency of iron in the stream water chemistry. Alteration of chlorite in the soil of CCw appears to produce a mixed-layer chlorite/vermiculite, which requires slow weathering. These factors may be attributed to organic interaction. The phengitic illite in the ChC soil alters to a mixed-layer illite/vermiculite. ChC has streamwater higher in alkalinity, pH, and total dissolved solute concentrations than CCw because of differences in bedrock chemistry and alteration. The stream water chemistry in both watersheds appears to be influenced mainly by the inorganic weathering of the bedrock and soil formation.

• OSTI ID: 6078503
• Report Number(s): CONF-9304188-; CODEN: GAAPBC
• Journal Information: Geological Society of America, Abstracts with Programs; (United States), Vol. 25:4; Conference: 42. annual Geological Society of America (GSA) Southeastern Section meeting, Tallahassee, FL (United States), 1-2 Apr 1993; ISSN 0016-7592
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
ALABAMA
WATERSHEDS
SOIL CHEMISTRY
GEOCHEMISTRY
KAOLINITE
MINERALOGY
PETROGRAPHY
SCANNING ELECTRON MICROSCOPY
SOILS
STREAMS
WATER CHEMISTRY
WEATHERING
X-RAY DIFFRACTION
ALUMINIUM COMPOUNDS
ALUMINIUM SILICATES
CHEMISTRY
COHERENT SCATTERING
DEVELOPED COUNTRIES
DIFFRACTION
ELECTRON MICROSCOPY
GEOLOGY
MICROSCOPY
MINERALS
NORTH AMERICA
OXYGEN COMPOUNDS
SCATTERING
SILICATE MINERALS
SILICATES
SILICON COMPOUNDS
SURFACE WATERS
USA
580000* - Geosciences