Imaging of Humic Substance Macromolecular Structures in Water and Soils
S. C. B. Myneni,
13*
J. T. Brown,
2
G. A. Martinez,
4
W. Meyer-Ilse
2
Humic substances (HSs) are the natural organic
polyelectrolytes formed from the biochemical weathering of plant and
animal remains. Their macromolecular structure and chemistry determine their role in biogeochemical processes. In situ spectromicroscopic evidence showed that the HS macromolecular structures (size and shape)
vary as a function of HS origin (soil versus fluvial), solution
chemistry, and the associated mineralogy. The HSs do not simply form
coils in acidic or strong electrolyte solutions and elongated
structures in dilute alkaline solutions. The macromolecular structural
changes of HSs are likely to modify contaminant solubility, biotransformation, and the carbon cycle in soils and sediments.
1 Earth Sciences Division,
2 Center for X-ray Optics, Lawrence
Berkeley National Laboratory, Berkeley, CA 94720, USA.
3 Department of Geosciences, Princeton University,
Princeton, NJ 08544, USA.
4 Agriculture
Experimental Station, University of Puerto Rico, Rio Piedras, PR 00928, USA.
*
To whom correspondence should be addressed. E-mail:
smyneni{at}princeton.edu
