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Mineralogical and Chemical Characteristics of Adirondack Spodosols: Evidence for Para‐ and Noncrystalline Aluminosilicate Minerals
Author(s) -
Johnson M. G.,
McBride M. B.
Publication year - 1989
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1989.03615995005300020030x
Subject(s) - imogolite , aluminosilicate , allophane , clay minerals , podzol , kaolinite , gibbsite , vermiculite , goethite , mineralogy , chemistry , geology , mica , glauconite , feldspar , soil water , adsorption , quartz , paleontology , biochemistry , organic chemistry , catalysis , soil science
Little is known about the para‐ and noncrystalline inorganic mineral phases in the soils of the northeastern USA. This research was conducted to obtain information on the chemistry, mineralogy, and reactivity of these materials in representative soils from this region. Using a combination of classical and nonclassical chemical and mineralogical methods, four Spodosols from Adirondack State Park, New York, were characterized. The principal clay‐sized layer silicates identified included: kaolinite, hydroxy‐interlayered vermiculite, and hydroxy‐interlayered smectite. These tended to be concentrated in E horizons. Minor amounts of clay‐sized feldspar and mica were also identified. Para‐ and noncrystalline materials were the most abundant constituents of the <2‐µm clay from B and C horizons. Up to 720 g/kg of the <2‐µm B horizon clay was para‐ or noncrystalline materials. In contrast, these materials, on average, accounted for only 65 g/kg in the E horizon <2‐µm clays. Reaction with NaF indicated that these materials have very high surface reactivities. Infrared spectrophotometry, Mössbauer, electron microscopy, and selective dissolution studies were used to characterize the <2‐ and <0.5‐µm clay fractions. Imogolite‐like materials, so called because of the lack of a characteristic imogolite doublet near 1000 cm −1 in the infrared, indicating poor development in the imogolite c‐axis direction, were identified in the <0.5‐µm clays from B and C horizons. Characteristic imogolite tubular morphology was not observed by electron microscopy. Mössbauer experiments indicated the presence of microcrystalline goethite and ferrihydrite; electron microscopy confirmed their presence. Para‐ and noncrystalline aluminosilicates appear to be a significant component of these soils; their high surface reactivities may have large influence on the chemical reactivity and physical characteristics of these soils.