Aquatic Sciences Meeting, Albuquerque 2001
| PC15 Photochemistry |
| Date: Thursday, February 15, 2001 |
| Location: Southwest Hall |
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| Stubbins, A, P, Ocean Research Group, University of Newcastle, Newcastle-upon-Tyne, United Kingdom, a.p.stubbins@ncl.ac.uk |
| Mopper, K, , Dept. of Chemistry, Washington State Univ. , Pullman, USA, |
| Aiken, G, R, USGS, Boulder, USA, |
| Kieber, D, J, State University of New York, College of Environmental Science and Forestry, Syracuse, USA, |
| Kitidis, V, , Ocean Research Group, University of Newcastle, Newcastle-upon-Tyne, United Kingdom, |
| Law, C, , Plymouth Marine Laboratory, Plymouth, United Kingdom, |
| Uher, G, , Ocean Research Group, University of Newcastle, Newcastle-upon-Tyne, United Kingdom, |
| Upstill-Goddard, R, U, Ocean Research Group, University of Newcastle, Newcastle-upon-Tyne, United Kingdom, |
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| CO PHOTOPRODUCTION FROM HUMIC SUBSTANCES IN SEAWATER AND FRESHWATER |
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| The photochemical reactivity of chromophoric dissolved organic matter (CDOM) in natural waters is a source of important trace gases (e.g. CO2, COS and CO). However, it is not known how the photoreactivity of humic substances (HS), a major component of CDOM, varies with source or is affected by the matrix. Sixteen HS isolated from diverse riverine, lake and marine environments were mixed with low CDOM seawater and deionized water (DIW) to a final concentration of 300 uM-C. Samples were irradiated in a solar simulator and analyzed for CO production and CDOM absorbance fading at 350nm. Unexpectedly, the photoreactivity of HS showed no matrix effects when CO photoproduction and absorbance fading in seawater and DIW were compared. CO production rates were ~4-45 nmol/L/h in both matrices, and absorbance losses were ~0.014-0.220 a/m/h. Both rates were strongly correlated to initial absorbance at 350nm and NMR aromaticity. Apparently, the presence of photoreactive species in the seawater matrix has no effect on HS reactivity from secondary photoreactions. Implications of these results are discussed with emphasis on the absence of matrix effects and in reference to field and laboratory work conducted with natural waters. |
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