| Main Title |
Investigation of the Electrostatic Properties of Humic Substances by Fluorescence Quenching. |
| Author |
Green, S. A. ;
Morel, F. M. M. ;
Blough., N. V. ;
|
| CORP Author |
Woods Hole Oceanographic Institution, MA. Dept. of Chemistry. ;Massachusetts Inst. of Tech., Cambridge. Dept. of Civil Engineering.;Environmental Research Lab., Athens, GA. Office of Research and Development. |
| Publisher |
1992 |
| Year Published |
1992 |
| Report Number |
EPA-R-815293; EPA/600/J-93/521; |
| Stock Number |
PB94-158821 |
| Additional Subjects |
Electrostatics ;
Humic acid ;
Fulvic acid ;
Environmental effects ;
Humus ;
Reprint ;
Decomposing organic matter ;
Cations ;
Photochemical reactions ;
Surface chemistry ;
Reaction kinetics ;
Environmental transport ;
Land pollution ;
Water pollution ;
Molecular weight ;
pH ;
Fluorescence quenching
|
| Holdings |
| Library |
Call Number |
Additional Info |
Location |
Last
Modified |
Checkout
Status |
| NTIS |
PB94-158821 |
Some EPA libraries have a fiche copy filed under the call number shown. |
|
07/26/2022 |
|
| Collation |
10p |
| Abstract |
A fluorescence quenching technique was employed to explore the electrostatic properties of fulvic acid (FA) and humic acid (HA). Cationic nitroxides were found to be up to 16 times more effective than neutral analogues in quenching the fluorescence of humic materials. The result is attributed to the enhanced Coulombic attraction of cations to the anionic FA or HA surface and is interpreted as an estimate of surface potential. Reduction of molecular charge at low pH and shielding of charge at high ionic strength produced diminished enhancements, consistent with this interpretation. High molecular weight fractions of HA have a higher apparent surface potential than lower molecular weight fractions, indicating that larger humic molecules may have an enhanced ability to bind metal ions. (Copyright (c) 1992 American Chemical Society.) |
