The 2022 wildfire season was significant. About 12,400 wildfires burned more than 650,000 acres across Texas. Time will tell what the 2023 season will bring, but the state has already entered spring wildfire season, which typically runs from February to April.
Forested areas are affected by wildfires more often and with greater intensity. Water from forested watersheds has historically met about half of the nation’s needs for drinking water. The heat from wildfires causes chemical reactions in soil, creating a type of organic matter called pyrogenic organic matter, which can impact those pristine water sources.
Thanks to a grant from the National Science Foundation, Texas A&M University researchers are studying these impacts, specifically the effect of pyrogenic organic matter on drinking water.
“Fuel for wildfires includes plant matter and soil organic matter,” said Dr. Garrett McKay, assistant professor in the Zachry Department of Civil and Environmental Engineering at Texas A&M and principal investigator. “Heat from wildfires induces a complex series of reactions that transform these structures into pyrogenic organic matter.”
The runoff of pyrogenic organic matter in wildfire-affected areas can negatively affect downstream water quality, aquatic biogeochemical processes and even water treatment plant operations.
McKay said previous research suggests that pyrogenic organic matter has a higher tendency to form highly toxic nitrogen-containing disinfection byproducts. And with studies also documenting the increasing frequency and severity of wildfires, it's vital to study the impacts of wildfires.
"I grew up hiking and skiing in the Sierra Nevada Mountain range in California. I also spent time in Colorado as a graduate student and postdoctoral researcher," McKay said. "Seeing the impacts of wildfires on these landscapes hits home."
His research group, Aquatic Chemistry Lab, is linking the chemical structure of organic matter with its reactivity in natural and engineered systems.
"Our preliminary study showed that the fluorescence quantum of pyrogenic organic matter is about 10 times higher than normal for natural organic matter," he said. "We think this has to do with the different chemical structures between these materials."
This grant is a collaboration with Dr. A. Peyton Smith, assistant professor in the soil and crop sciences department at Texas A&M, and Dr. Amanda K. Hohner, assistant professor in the civil engineering department at Montana State University.
The team will also perform high-frequency monitoring of a wildfire-impacted watershed using optical, solar-powered sensors that take readings in the field every 15 minutes, transmitting high-frequency water quality signatures. McKay obtained these sensors thanks to a Texas Water Resources Institute grant.