Session: Undergraduate Research Posters: Environmental Chemistry:

The optical properties of chromophoric dissolved organic matter (CDOM), the UV and visible light-absorbing component of dissolved organic matter (DOM), have been used extensively to determine levels, identify sources, and track transformations of DOM in natural waters. Traditional optical techniques are primarily based on steady-state absorbance and steady-state fluorescence measurements. For example, three-dimensional excitation and emission matrix (EEMs) fluorescence spectra have been used extensively to characterize CDOM in these systems. One of the challenges in interpreting EEMs is that fluorescent material from different sources can fluoresce in the same region of the EEM. For example, both terrestrial organics and oil products can fluoresce in the protein region of a typical EEM, leading to difficulty in using EEMs to study oil-impacted waters. Time-resolved fluorescence spectroscopy has the potential to differentiate between these fluorescent materials. A series of EEM and fluorescent lifetime measurements were made on a range of natural dissolved organic water samples and oil products to test the viability of using time-resolved fluorescence spectroscopy to better characterize DOM in natural waters. The results show promise with lifetimes of natural DOM like plant leachates being less than 10 ns and oil products typically having a lifetime component of greater than 20 ns.

Warren De Bruyn

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