Every year, an estimated four percent of the world's vegetated land surface burns, leaving more than 250 megatons of carbonized plants behind.
Every year, an estimated four percent of the world's vegetated land surface burns, leaving more than 250 megatons of carbonized plants behind. For the first time, a study by the University of Vienna has now recorded elevated concentrations of environmentally persistent free radicals (EPFR) in these charcoals - in some cases even up to five years after the fire. These EPFR may generate reactive substances, which in turn harm plants and living organisms. The research team led by Gabriel Sigmund and Thilo Hofmann analyzed charcoal samples collected from forest, shrubland and grassland fires in different climatic zones. The study is published in Nature Communications Earth & Environment.
Reactive oxygen species (ROS) cause oxidative stress at the cellular level. Research shows that this way, amongst others, they inhibit the germination capacity of plants, produce cytotoxins or exert toxic effects on aquatic invertebrates. Environmentally persistent free radicals (EPFR) are potential precursors of ROS because they can react with water to form these radical species. "Therefore, EPFR are associated with harmful effects on the ecosystem and human health," explains Gabriel Sigmund, the lead investigator of the study.
"Our study shows that these environmentally persistent free radicals can be found in large quantities and over a long period of time in fire derived charcoal," reports Sigmund, environmental geoscientist at the Center for Microbiology and Environmental Systems Science (CMESS) at the University of Vienna. In all 60 charcoal samples from ten different fires, the researchers detected EPFR in concentrations that exceeded those typically found in soils by as much as ten to a thousand times. Other than expected, this concentration remained stable for at least five years, as an analysis of charcoal samples showed which were gathered at the same location and over several years after a forest fire. "The more stable the environmentally persistent free radicals are, the more likely it is that they will have an impact on ecosystems over longer periods of time," explains Thilo Hofmann, co-author of the study and head of the research group.
Read more at: University of Vienna
In samples from ten different fires, the researchers detected EPFR in concentrations that exceeded those typically found in soils by as much as ten to a thousand times. Photo Credit: © Stefan Doerr