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Mar13
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more lessLinking Dissolved Organic Matter Composition with Photoreactivity Using High-Resolution Mass Spectrometry
Abstract
The composition of dissolved organic matter (DOM) determines its photochemical reactivity and ability to form photochemically produced reactive intermediates (PPRI). We collected water samples in the St. Louis River in the United States, which includes of variety of DOM sources and processing. Bulk characterization techniques, such as measurements of total organic carbon and ultraviolet-visible spectroscopy, show the quantity of DOM, apparent molecular weight, and aromaticity all decrease downstream in the system. Characterization at the molecular level using Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS) reveals that saturation of DOM generally increases downstream. Photochemical experiments measuring quantum yields for PPRI formation show that upstream samples are more efficient at producing hydroxyl radical (•OH), while downstream samples are more efficient at producing triplet DOM (3DOM) and singlet oxygen (1O2). Spearman rank correlations were used to correlate formula intensities, as determined by FT-ICR MS, to observed quantum yields for PPRI formation and to photodegradation rate constants of target contaminants (atorvastatin, carbamazepine, DEET, and venlafaxine). These analyses indicate that the more saturated DOM pool most strongly correlated to formation of 3DOM and 1O2 is the same pool of DOM correlated to photodegradation of atorvastatin, carbamazepine, and venlafaxine. In contrast, highly aromatic DOM formulas are strongly correlated to •OH formation and DEET photodegradation. Together, these results demonstrate how DOM composition affects photoreactivity and contaminant fate.
Bio
Associate Professor Christy Remucal (née Christina Renée Keenan) leads the Aquatic Chemistry group at the University of Wisconsin-Madison and is the Director of the Water Science and Engineering Laboratory. She is a faculty member in the Department of Civil & Environmental Engineering, the Environmental Chemistry & Technology Program, and the Limnology & Marine Science Program. She holds an MS (2004) and a PhD (2009) in Civil & Environmental Engineering from the University of California, Berkeley, and a BS (2003) in Environmental Engineering Science from Massachusetts Institute of Technology. Before joining the UW-Madison faculty, Christy completed a post-doc in the Institute for Biogeochemistry and Pollutant Dynamics at the Swiss Federal Institute of Technology.
TIME Friday, March 13, 2020 at 2:00 PM - 3:00 PM
LOCATION A230, Technological Institute map it
CONTACT Tierney Acott tierney-acott@northwestern.edu EMAIL
CALENDAR McCormick - Civil and Environmental Engineering