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Water‐Dispersible Soil Organic‐Mineral Particles: II. Inorganic Amorphous and Crystalline Phases in Density Fractions of Clay‐Size Particles
Author(s) -
Spycher G.,
Young J. L.
Publication year - 1979
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/sssaj1979.03615995004300020018x
Subject(s) - amorphous solid , dissolution , particle size , organic matter , phase (matter) , particle (ecology) , chemical engineering , mineralogy , clay minerals , hydrogen peroxide , materials science , chemistry , geology , crystallography , organic chemistry , engineering , oceanography
Water‐dispersible clay‐organic particles from six epipedons and one Bh horizon were fractionated by density. After oxidation of organic matter in hydrogen peroxide, the amorphous particle phase was removed using a kinetic method and analyzed for Si, Al, and Fe. Light particles contained high levels of amorphous oxides and a poorly ordered phyllosilicate matrix. Heavy particles had low levels of amorphous oxides and a more crystalline matrix. A continuum in particle compositions and properties between the density extremes was observed and explained in terms of an aggregate model proposed in part I of the study. Molar silica to alumina ratios of the amorphous phase in particles ranged from 0.2 to 6.7. Low ratios (<1) occurred in particles from an Aquod Bh horizon and were attributed to organically complexed Al. The amorphous particle phase, mineral matter dissolving at a fast rate, was allophanic (low ratio) in two Andepts, and highly siliceous in an Argid. Intermediate ratios in other soils may have resulted in part from disordered phyllosilicates.