The chemical structure of highly aromatic humic acids in three volcanic ash soils as determined by dipolar dephasing NMR studies

Journal Article · Sun Jan 01 04:00:00 EST 1989 · Geochimica et Cosmochimica Acta; (USA)

DOI:https://doi.org/10.1016/0016-7037(89)90278-0· OSTI ID:7243004

Hatcher, P G ^[1]; Schnitzer, M ^[2]; Vassallo, A M; Wilson, M A ^[3]

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1. Geological Survey, Reston, VA (USA)
2. Agriculture Canada, Ottawa, Ontario (Canada)
3. CSIRO, New South Wales (Australia)

Dipolar dephasing {sup 13}C NMR studies of three highly aromatic humic acids, one from a modern soil and two from paleosols, have permitted the determination of the degree of aromatic substitution. From these data and the normal solid-state {sup 13}C NMR data the authors have been able to develop a model for the average chemical structure of these humic acids that generally correlates well with permanganate oxidation data. The models depict these humic acids as benzene di- and tricarboxylic acids interconnected by biphenyl linkages. An increasing degree of substitution is observed with increasing geologic age. These structures may be characteristic of the resistant aromatic part of the core of humic substances that survives degradation.

• OSTI ID: 7243004
• Journal Information: Geochimica et Cosmochimica Acta; (USA), Journal Name: Geochimica et Cosmochimica Acta; (USA) Vol. 53:1; ISSN GCACA; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
AROMATICS
CHEMICAL REACTIONS
CHEMISTRY
GEOCHEMISTRY
GEOLOGIC HISTORY
HUMIC ACIDS
IGNEOUS ROCKS
MANGANESE COMPOUNDS
MATHEMATICAL MODELS
MOLECULAR MODELS
MOLECULAR STRUCTURE
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC MATTER
OXIDATION
OXYGEN COMPOUNDS
PERMANGANATES
PHASE TRANSFORMATIONS
ROCKS
SOIL CHEMISTRY
SOILS
STRUCTURAL CHEMICAL ANALYSIS
TRANSITION ELEMENT COMPOUNDS
VOLCANIC ROCKS
VOLCANISM
WEATHERING