EPR Spectroscopy of Natural Organic Matter (NOM), Fractions of NOM, and Model Biogeochemical Electron Shuttles
EMSL Project ID
2119
Abstract
The first study of NOM by electron paramagnetic resonance spectroscopy (EPR), done over 40 years ago, reported that NOM showed paramagnetism. Since 1962, this paramagnetism has been attributed to stable organic free radicals associated with the presence of the quinone/hydroquinone redox couple.Over the last 20 years, there have been many studies on NOM by EPR spectroscopy. Studies in which the effects of variables such as NOM extraction procedures, temperature, hydrolysis and methylation of NOM, oxidation and reduction of NOM, and pH have on the EPR signal have all been reported. Most recently, an EPR study was done on NOM fractions that also concluded that the quinone/hydroquinone moieties are responsible for the redox activity of NOM.We have obtained electrochemical data on several NOM fractions and model NOM compounds and would like to correlate our results with EPR data. There are 4 types of information that can be obtained from EPR spectra: (i) radical concentration (ii) hyperfine structure (if any) (iii) width of the absorption line and (iv) g-values. This data will be combined with the electrochemical data already obtained to provide correlations between the NOMs electrochemical properties and NOMs free radical concentrations, for example.
Project Details
Project type
Exploratory Research
Start Date
2000-12-15
End Date
2002-09-03
Status
Closed
Released Data Link
Team
Principal Investigator