posted on 2024-02-23, 19:35authored bySierra Jech, Clifford Adamchak, Sean C. Stokes, Marin E. Wiltse, Jessica Callen, Jacob VanderRoest, Eugene F. Kelly, Eve-Lyn S. Hinckley, Holly J. Stein, Thomas Borch, Noah Fierer
Wildfires at the wildland-urban interface (WUI) are increasingly
common. The impacts of such events are likely distinct from those
that occur strictly in wildland areas, as we would expect an elevated
likelihood of soil contamination due to the combustion of anthropogenic
materials. We evaluated the impacts of a wildfire at the WUI on soil
contamination, sampling soils from residential and nonresidential
areas located inside and outside the perimeter of the 2021 Marshall
Fire in Colorado, USA. We found that fire-affected residential properties
had elevated concentrations of some heavy metals (including Zn, Cu,
Cr, and Pb), but the concentrations were still below levels of likely
concern, and we observed no corresponding increases in concentrations
of polycyclic aromatic hydrocarbons (PAHs). The postfire increases
in metal concentrations were not generally observed in the nonresidential
soils, highlighting the importance of combustion of anthropogenic
materials for potential soil contamination from wildfires at the WUI.
While soil contamination from the 2021 Marshall Fire was lower than
expected, and likely below the threshold of concern for human health,
our study highlights some of the challenges that need to be considered
when assessing soil contamination after such fires.