posted on 2024-01-26, 22:31authored byCarmen
M. Villarruel, Linda A. Figueroa, James F. Ranville
Wildfires at the wildland–urban interface (WUI)
are increasing
in frequency and intensity, driven by climate change and anthropogenic
ignitions. Few studies have characterized the variability in the metal
content in ash generated from burned structures in order to determine
the potential risk to human and environmental health. Using inductively
coupled plasma optical emission spectroscopy (ICP-OES) and inductively
coupled plasma mass spectrometry (ICP-MS), we analyzed leachable trace
metal concentration in soils and ash from structures burned by the
Marshall Fire, a WUI fire that destroyed over 1000 structures in Boulder
County, Colorado. Acid digestion revealed that ash derived from structures
contained 22 times more Cu and 3 times more Pb on average than surrounding
soils on a mg/kg basis. Ash liberated 12 times more Ni (mg/kg) and
twice as much Cr (mg/kg) as soils in a water leach. By comparing the
amount of acid-extractable metals to that released by water and simulated
epithelial lung fluid (SELF), we estimated their potential for environmental
mobility and human bioaccessibility. The SELF leach showed that Cu
and Ni were more bioaccessible (mg of leachable metal/mg of acid-extractable
metal) in ash than in soils. These results suggest that structure
ash is an important source of trace metals that can negatively impact
the health of both humans and the environment.