Stanford study examines the lasting effects wildfires have on soil, posing new problems

ByTim Didion and Drew Tuma KGO logo
Tuesday, June 4, 2024
Stanford study examines the lasting effects wildfires have on soil
A Stanford study identified toxic chemicals in soil impacted by wildfires, possibly slowing regrowth as toxic metal particles travel long distances.

STANFORD, Calif. (KGO) -- The grey smoky skies can be seen for hundreds of miles. But now researchers are on the trail of wildfire threats that are invisible to the naked eye. The result of intense heat, from wildfires burning longer and hotter.

"When we start getting really severe fires, we see a transformation where the really, really intense fires leave these lasting impacts on the soil," says Professor Scott Fendorf, Ph.D., of Stanford's Doerr School of Sustainability.

RELATED: Wildfires can unlock toxic metals from soil, Stanford study shows

Stanford study shows intense heat from wildfires can transform natural elements in soil into Chromium 6, a toxic metal believed to cause cancer.

Fendorf is leading a multi-year study. The team examined soils in forest areas that have been slow to recover from recent wildfires in the Sierra and elsewhere. Although early research has pointed to cycles of drought, Fendorf and his colleagues identified toxic concentrations of chemicals in the soil which could also be slowing regrowth.

"It really shows that it isn't just drought, that it really is a consequence of a number of toxins being produced that end up altering the soil along with physical changes that then retard ecosystem recovery," he explains.

Fendorf believes the chemical changes are driven by the intense heat from recent fires. In an earlier study, the team found the process can change certain naturally occurring metals into a toxic compound called Chromium 6. Now the team is working to learn how far the toxic particles might be able to travel. He says the results are still preliminary, but concerning.

MORE: Wildfires in Canada force evacuations as harmful smoke blows into the US

"We've started to reveal and others are recognizing, and that is that the travel distance distances for a lot of these aerosols, small particles can be quite pronounced and that as an example, the Canadian wildfires were bringing smoke down into New York, into Washington, D.C. and throughout the eastern seaboard, long distances from the fire centers," he says.

Stanford researcher Dr. Sharon Chinthrajah, M.D., studies pulmonary allergies and their effects on the immune system. She's concerned about the unknown levels of exposure.

"The total amount is what we're worried about absorbing whether that's through the skin, through our respiratory tract, through our eyes, right? Or ingesting it. So these are all important considerations that we need to think about," says Dr. Chinthrajah.

MORE: Most destructive California wildfires in history

Professor Fendorf says his team will be working through the current wildfire season, trying to develop threat models based on everything from geology to a fire's duration, to wind conditions. All in an effort to keep firefighters and others safer from toxic exposure, and an era of climate change.

Researchers say another key concern moving forward will be the safety of drinking water. And they're hoping to learn more about the effects of runoff from contaminated soils.

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