Aquatic Sciences Meeting, Albuquerque 2001

SS02 Photochemical Reactions In Surface Waters: A Major Issue in the 21st Century? (Environmental Connections)

Date: Thursday, February 15, 2001, Time: 2:30:00 PM

Location: San Miguel

White, E, M, Ohio State University, Columbus, USA, white.575@osu.edu

Chin, Y, , Ohio State University, Columbus, USA, yo@geology.ohio-state.edu

PHOTOCHEMICAL PRODUCTION OF HYDROXYL RADICAL BY DISSOLVED ORGANIC MATTER

In natural aquatic systems, a potentially important source of photochemically generated hydroxyl radical (OH·) is dissolved organic matter (DOM). The degree to which OH· is produced by sunlight in nitrate-poor waters is dependent upon the types of organic matter present. In this study, the ability of various DOMs to photochemically produce OH· was investigated. Hydroxyl radical production rates (pOH·) were measured for a variety of isolated DOMs as well as for filtered freshwater samples. The DOMs studied span a range of geochemical endmembers, from solely algal derived materials to those substances originating from primarily terrestrial sources. Isolates were characterized by UV-vis and 13C-NMR spectroscopy. pOH· levels, measured using methanol as a probe and a xenon light source, ranged from 2.3 to 13.2 x 10-11 M-1s-1 per mg C/L. Typically, more aromatic DOM resulted in higher OH· production rates. Complexed iron may also play an important role in OH· production, but a poorer correlation was observed between pOH· and total iron.

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Aquatic Sciences Meeting, Albuquerque 2001

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