Wildfires serve an essential role in forested ecosystems by influencing nitrogen cycling, creating bio-reactive charcoal, and thinning accumulated fuel loads. However, surface water quality is also impacted by an increased transport of natural organic matter (NOM), most notably organic carbon and organic nitrogen, via overland runoff. The acuteness to water quality is largely attributed to the heating duration and temperature terrestrial NOM is exposed to during a wildfire. Although much of the carbon rich detritus in the O-horizon is mineralized during a burn event, A-horizon NOM experiences an increase in solubility due to heat induced physiochemical changes. The increase in NOM solubility not only effects a stream’s ecological functions, but also creates complications for downstream communities that rely on burned watersheds for water resources.  Disinfection byproducts (DBPs) are harmful halogenated compounds formed through reactions between NOM and chlorine during the disinfection phase of water treatment. Past research has found that formation potential (FP) of regulated carbonaceous DBPs (C-DBPs) and unregulated nitrogenous (N-DBPs) decreases and increases, respectively, with increasing burn severity. Moreover, our early results have found that five C-DBPs (CHCl<sub>3</sub>, CHCL<sub>2</sub>Br, DCAA, TCAA, 1,1,1-TCP) and two N-DBPs (DCAN, TCAN) exhibit higher FP at moderate burn temperatures (250-350 °C) in a controlled laboratory setting. These results suggest that communities affected by wildfires could experience a heightened risk of exposure to C/N-DBPs; most notably to unregulated and highly toxic N-DBPs.  As wildfire intensity and severity continues to rise as a result of climate change, there is impetus to understand wildfire’s continual effects on drinking water resources. Therefore, this project attempts to further our understanding of C/N-DBP FP as a function of burn temperature. Soils were collected from a variety of areas throughout Colorado’s Front Range and heated in a muffle furnace to simulate wildfire burning. The heat treated soils were leached into water and chlorinated to simulate the disinfection phase of water treatment. FP of Sixteen C-DBPs and four N-DBPs was measured with gas chromatography and electron capture detection (GC-ECD). Additionally, the hydrophobic and transphilic fractions of heat treated NOM were isolated through high performance liquid chromatography, chlorinated, and had C/N-DBP FP measured with GC-ECD.

Wildfires give rise to conditions encouraging disinfection byproduct formation

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.