Wildfires don't just pollute the air, rain may turn its smoke into fertilizer
Wildfire smoke is usually discussed as an airborne pollutant and a threat to human health. But when smoke and rain coincide, nutrients released by burned landscapes rain back down. A new study finds that smoke-rain events can deliver large bursts of nitrogen, phosphorus and potassium—three nutrients essential to life—across ecosystems in the United States. As wildfires become more frequent, these…
Wildfires produce smoke that poses a threat to human health, but when that smoke encounters rain, nutrients released by the scorched land can be carried back down to ecosystems, according to a new study. Lead researcher Alexandra Ponette-González, an urban ecologist at the University of Utah, highlighted the importance of considering what falls from the atmosphere just as much as what goes up.
The study, published in the journal Global Change Biology, is the first to examine how wildfire smoke particles are transported to ecosystems through rainfall across the United States over multiple years. Researchers analyzed satellite-derived smoke observations and national rainfall data at 250 sites in 16 climate regions during 2014, 2020 and 2022.
Despite being infrequent, smoke-rain events delivered a significant portion of essential nutrients—nitrogen, phosphorus and potassium—to the study sites. Once dissolved in water, these nutrients become immediately available for uptake by plants and other organisms. Regions with the most smoke-rain events shifted over time, with the Upper Midwest, Northern Rockies, Southwest and Ohio Valley being the top hotspots in 2014, 2020 and 2022, respectively.
The findings demonstrate that wildfire emissions can be a substantial source of material deposited into ecosystems, but the ecological effects depend on the specific characteristics of the receiving ecosystem.
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