Event Title

Wildfire and Water Quality: Using Fluorescence Spectroscopy to Predict the Biodegradability of Dissolved Organic Matter

Presenter Information

Leika Patch

Location

Logan Golf & Country Club, Logan, UT

Start Date

3-26-2019 5:00 PM

End Date

3-26-2019 7:00 PM

Description

Megafires are sweeping the western United States, increasing erosion and altering lateral transport of organic matter to surface waters. Burn-mobilized dissolved organic matter (DOM) could influence downstream nutrient loading and eutrophication, depending on DOM biodegradability. Though biodegradability is time-consuming to quantify with lab assays, there is some evidence that DOM biodegradability can be predicted with optical properties. In this context, we coupled incubation experiments with parallel factor analysis (PARAFAC) modeling of fluorescence data to characterize the reactivity and type of DOM present before and after a 610 km2 megafire in central Utah. We used samples spanning an extreme flow event to test the concentration-discharge relationships of DOM biodegradability and optical properties for burned and unburned catchments. We observed large shifts in both composition and biodegradability of DOM for all sites. However, burned catchments had DOM that differed substantially from unburned catchments, potentially due to increased interaction with mineral particles and altered sources due to combustion of surface vegetation. We discuss the reliability of optical properties for predicting DOM biodegradability and how these methods could help quantify biodegradable DOM fluxes that may trigger hypoxia or otherwise alter aquatic food webs.

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Mar 26th, 5:00 PM Mar 26th, 7:00 PM

Wildfire and Water Quality: Using Fluorescence Spectroscopy to Predict the Biodegradability of Dissolved Organic Matter

Logan Golf & Country Club, Logan, UT

Megafires are sweeping the western United States, increasing erosion and altering lateral transport of organic matter to surface waters. Burn-mobilized dissolved organic matter (DOM) could influence downstream nutrient loading and eutrophication, depending on DOM biodegradability. Though biodegradability is time-consuming to quantify with lab assays, there is some evidence that DOM biodegradability can be predicted with optical properties. In this context, we coupled incubation experiments with parallel factor analysis (PARAFAC) modeling of fluorescence data to characterize the reactivity and type of DOM present before and after a 610 km2 megafire in central Utah. We used samples spanning an extreme flow event to test the concentration-discharge relationships of DOM biodegradability and optical properties for burned and unburned catchments. We observed large shifts in both composition and biodegradability of DOM for all sites. However, burned catchments had DOM that differed substantially from unburned catchments, potentially due to increased interaction with mineral particles and altered sources due to combustion of surface vegetation. We discuss the reliability of optical properties for predicting DOM biodegradability and how these methods could help quantify biodegradable DOM fluxes that may trigger hypoxia or otherwise alter aquatic food webs.