Aquatic Sciences Meeting, Albuquerque 2001

CS25 Organic Carbon Dynamics

Date: Wednesday, February 14, 2001, Time: 2:15:00 PM

Location: Acoma/Zuni/Tesuque

Macalady, D, L, Colorado School of Mines, Golden, CO, USA, dmacalad@mines.edu

McQuillan, A, J, University of Otago, Dunedin, New Zealand, JMcquillan@Alkali.otago.ac.nz

FTIR-ATR MEASUREMENTS OF NATURAL ORGANIC MATTER ADSORBED TO MINERAL SURFACES

Fourier Transform Infrared Spectroscopy with an attenuated total reflectance cell (FTIR-ATR) provided spectra of natural organic matter (NOM) adsorbed from natural waters onto synthetic hematite particles. The hematite was applied to the ATR crystal as a suspension of approximately 80 nanometer particles. The suspension was allowed to dry, leaving a thin film of hematite on the crystal surface. FTIR background spectra were obtained with pure water over the film. Upon passage of NOM solutions (10-40 mg C/L) over the surfaces, spectra of adsorbed NOM were obtained as a function of time and NOM concentration. Adsorbed NOM could be easily removed with passage of a basic solution (pH 11) over the surface. Differences in spectra were observed as a function of exposure time, NOM origin, and NOM concentration. This technique provides a potentially powerful tool for investigations of NOM-surface interactions for various mineral surfaces, the fractionation of solution phase NOM caused by interactions with mineral surfaces, and provides a means to identify differences among NOM samples based on the IR spectra of their adsorbed fractions.

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Aquatic Sciences Meeting, Albuquerque 2001

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