Molecular structure in soil humic substances: The new view

Journal Article · Thu Apr 21 04:00:00 EDT 2005 · Environmental Science and Technology

DOI:https://doi.org/10.1021/es050778q· OSTI ID:925419

Sutton, Rebecca; Sposito, Garrison

A critical examination of published data obtained primarily from recent nuclear magnetic resonance spectroscopy, X-ray absorption near-edge structure spectroscopy, electrospray ionization-mass spectrometry, and pyrolysis studies reveals an evolving new view of the molecular structure of soil humic substances. According to the new view, humic substances are collections of diverse, relatively low molecular mass components forming dynamic associations stabilized by hydrophobic interactions and hydrogen bonds. These associations are capable of organizing into micellar structures in suitable aqueous environments. Humic components display contrasting molecular motional behavior and may be spatially segregated on a scale of nanometers. Within this new structural context, these components comprise any molecules intimately associated with a humic substance, such that they cannot be separated effectively by chemical or physical methods. Thus biomolecules strongly bound within humic fractions are by definition humic components, a conclusion that necessarily calls into question key biogeochemical pathways traditionally thought to be required for the formation of humic substances. Further research is needed to elucidate the intermolecular interactions that link humic components into supramolecular associations and to establish the pathways by which these associations emerge from the degradation of organic litter.

• Research Organization: COLLABORATION - UCBerkeley
• DOE Contract Number: AC02-05CH11231
• OSTI ID: 925419
• Report Number(s): LBNL--59827
• Journal Information: Environmental Science and Technology, Journal Name: Environmental Science and Technology Journal Issue: 23 Vol. 39; ISSN ESTHAG; ISSN 0013-936X
• Country of Publication: United States
• Language: English

Related Subjects

08 HYDROGEN
ABSORPTION
HYDROGEN
MOLECULAR STRUCTURE
NUCLEAR MAGNETIC RESONANCE
ORGANIZING
PYROLYSIS
SOILS
SPECTROSCOPY