Dissolved organic matter character across a wildfire affected stream network

There has been an increase in large, high severity wildfires in recent years, leading to potential landscape, hydrologic, and water quality impacts. In particular, there is increasing concern about the effects of wildfires on dissolved organic matter (DOM) due to its role in aquatic ecosystem health and drinking water treatment. While there’s evidence that wildfire can alter the chemical composition of DOM, there has been substantial variability in observations. We aim to increase our understanding of post-fire changes in DOM character by using excitation emission matrices (EEMs) data from high spatial resolution stream sampling. Following a large 2020 wildfire in Oregon, we sampled >120 stream sites across the fire affected stream network. Sampling was repeated across seasonal hydrologic conditions to capture variation in hydrologic pathways and organic matter sources. We will use spatial stream network models to explore seasonal and spatial patterns of DOM character across the basin and to understand factors contributing to variability in character metrics across the sub-basin. Our work will contribute to a mechanistic understanding of how wildfire impacts DOM sources and character, which is critical to predict wildfire effects on DOM and preserve aquatic ecosystem health and source water quality.

Primary Presenter: Katie Wampler, Oregon State University (katie.wampler@oregonstate.edu)

Authors:

Katie Wampler, Oregon State University  (katie.wampler@oregonstate.edu)

Kevin Bladon, Oregon State University  (kevin.bladon@oregonstate.edu)

Allison Myers-Pigg, Marine Sciences Laboratory, Pacific Northwest National Laboratory  (allison.myers-pigg@pnnl.gov)

Alan Roebuck, Marine Sciences Laboratory, Pacific Northwest National Laboratory  (alan.roebuck@pnnl.gov)