Wildfires may be emitting more carbon and toxic chemicals than assumed, by changing soil composition: Study

Wildfires may be releasing more global warming carbon dioxide and toxic chemicals than previously expected by changing the composition of the soil systems they burn, new research shows. Research has revealed this.

The charcoal-like remains of charred wood and other organic compounds, collectively known as black charcoal, give scientists hope There is a possibility that carbon dioxide cannot be captured for a long time.

“Black carbon from forest fires may actually be more easily converted to carbon dioxide by microorganisms than previously thought,” said co-author Doerr Sustainability at Stanford University. Scott Fendorf, a professor at the graduate school, said in a statement.

The researchers acknowledged that wildfires can benefit ecosystems in a number of ways, including increasing soil nitrogen content and the water solubility of organic carbon, promoting regrowth.

Nevertheless, the authors noted that recovery also depends on the presence of other chemicals called karrikins, since many seeds can only germinate if these molecules are present in sufficient quantities.

Wildfires, on the other hand, can also double soil concentrations of toxic chemicals called polycyclic aromatic hydrocarbons, triggering reactions that prevent revegetation. These effects may explain why trees are slow to recover after wildfires burn areas of the Rocky Mountains, the authors say.

To investigate how wildfires affect soil organic matter, researchers conducted an extensive review of recent relevant research, including data from laboratory-based simulations and field observations.

By taking this approach, the researchers were able to “combine organic and inorganic chemistry” rather than just looking at one area of ​​focus related to wildfires, said co-first author Claudia Avila. Says. Claudia Avila was a postdoctoral researcher at Stanford University at the time of the research and is now an assistant professor. He is at the University of San Diego.

“A better understanding of soil molecular mechanisms could help explain, for example, why drinking water from forest fire-affected watersheds suddenly becomes more toxic, or why forests don’t return. “It’s possible,” said lead author Thomas Borch of Colorado. The university’s soil chemists said in a statement:

The authors explained that one way wildfires contaminate watersheds is by converting metals into more dangerous forms that move through the environment and eventually reach water supplies.

For example, high levels of dangerous forms of chromium have been found in many burn sites. This is due to heat converting a naturally occurring harmless form of the metal. The study found that at sites where long-term fires heated the soil to high temperatures, contamination persisted for months until the next heavy rain event.

The authors expressed hope that the results of this study could inform future wildfire management strategies, thereby helping to reduce risks such as the release of toxic metals into drinking water supplies. .

“By identifying areas where chromium is likely to be released, for example, we can call for low-intensity prescribed burns, reducing the chance of high-intensity fires releasing toxins,” Avila says. he said.