Spectroscopic correlations involving humic substance photochemical reaction rates

ENVR 164

Renee Dalrymple, rdalr9yo@umw.edu, Amy Carfagno, acarf2va@umw.edu, and Charles M. Sharpless, csharple@umw.edu. Department of Chemistry, University of Mary Washington, Fredericksburg, VA 22401
The photochemical production of singlet oxygen (1O2) has been studied for a variety of humic substance (HS) samples. A strong correlation exists between the 1O2 quantum yields and the ratio of the HS absorbance at 250 nm to that at 365 nm (E2/E3 ratio). The applicability of this correlation to predicting production rates in natural samples is presently being studied and the results will be presented. Experiments are also underway to investigate whether a similar correlation holds for the photochemical production of superoxide (O2-), an important precursor of hydrogen peroxide in natural waters. Interpreting the results in terms of a charge-transfer model for HS absorbance should help shed light on the molecular-level precursors in HS that interact with O2 to produce 1O2 and O2-.
 

General Papers
6:00 PM-8:00 PM, Wednesday, August 22, 2007 BCEC -- Exhibit Hall - B2, Poster

Division of Environmental Chemistry

The 234th ACS National Meeting, Boston, MA, August 19-23, 2007