Explore CWEST LabsAs former INSTAAR graduate student Rachel Gabor explained in her (successful – congrats Rachel!) Ph.D. defense, dissolved organic matter (DOM) matters.

DOM is found in waters everywhere giving a brown color, for example, to waters in bogs and swamps. In aquatic ecosystems, it can affect the way nutrients such as nitrogen and phosphorus are transported through watersheds. It can also affect the depth to which sunlight can penetrate lakes in sufficient intensities to allow photosynthesis to occur. Additionally, DOM acts as a sunscreen protecting fish, for instance, from ultraviolet radiation. In wastewater treatment, DOM can interact with chlorine to create disinfection byproducts.

DOM Lab Jess Ebert

INSTAAR graduate student, Jess Ebert, is using the Fluoromax-4 to analyze the fluorescence properties of samples from the H.J. Andrews Experimental Forest Long-Term Ecological Research site located in Oregon’s Cascade Mountains. Photo by Karen Cozzetto.

DOM is made up of numerous different chemicals, kind of like a soup explains Rachel.  In the Dissolved Organic Matter Characterization Lab, researchers use various instruments to provide information about the properties of the DOM, or the DOM ingredients if we continue with the soup analogy.  Because each location has different sources for DOM, each place will have its own particular DOM recipe.

The lab’s new Shimadzu 5000 Total Organic Carbon analyzer provides data on total DOM concentrations.  Investigators, explains INSTAAR graduate student Garrett Rue, also typically employ a series of detailed lab methods such as resin chromatography and size-excluding filtration, to isolate aspects of the DOM pool.  Researchers can then run either the whole sample or isolated fractions through the lab’s Agilent ultraviolet spectrophotometer, which provides information about the DOM’s absorption characteristics.  The lab’s two spectrofluorometers – a Fluoromax-3 and Fluoromax-4 – in combination with computer modeling provide data on DOM’S fluorescence characteristics.   This is how the DOM when exposed to certain wavelengths of light absorbs and then re-emits that light.  By understanding these different DOM traits, researchers can then gain a better understanding of the roles that DOM plays in aquatic environments and ecosystem.

Contacts: Dr. Diane McKnight, Lab Director - diane.mcknight@colorado.edu; Chris Florian, post-doctoral reseracher Christopher.Florian@Colorado.EDU, Garrett Rue, graduate student -garrett.rue@gmail.com 
Link: DOM Characterization Lab INSTAAR webpage