RAPID: Nanoparticulate metals released from wetland soils by wildfire

About This Grant

Wildfires are becoming more prevalent and are expanding out of wilderness areas and into the wildland-urban interface, including densely packed suburbs. The most devastating effects of these fires are apparent - the loss of homes, communities, and sometimes lives. Beyond the physical destruction, one unanswered question about the environmental impact of structure burning is whether fire liberates metal particles from household and structural components. Metals are found in everything from pipes to electronics to paints and pigments. Metals such as lead, copper, zinc, cadmium, and others can be toxic to the environment and humans. Once released, small metal particles can be transported by wind with subsequent deposition by rain and snow throughout different environments. The December 31, 2021 Marshall fire in Boulder County, Colorado burned more than 1000 structures, causing unknown effects on metal release to the surrounding environment. The research team at Colorado School of Mines will employ state of the art particle analysis techniques to determine if metal particles are present in ash samples from burned structures. If found, further analysis will determine whether the concentrations are significant and humans are at risk from toxicological effects. The potential for metals to be absorbed by human lungs will be assessed by leaching metals from the ash into simulated lung fluids. The project will provide essential information to increase understanding of fire-derived metals while furthering analytical capabilities. The research team will hold virtual and classroom forums involving the Boulder community aimed at educating the community on the findings of the research, sharing the health impacts of nanoscale particles, and providing hands-on experiments for students. The ash and smoke generated from the Marshall fire has the potential to be more harmful to both the environment and human health than materials generated from wildland fires. Specifically, the anthropogenic materials burned may lead to the presence of metal-containing nanoparticles (diameter < 100 nm) in the resulting ash and soot. The project goal over the next 12 months is to determine the amount of metal (Cu, Cd, Hg, Pb, Zn among others) present in nanoparticle form in ash and soot. The research team will collect samples from the area affected by the Marshall fire, focusing on ash from within burned homesites, nearby soils, and surface waters located downwind of the burned area. Samples collected in non-urban, upwind sites will serve as controls. This RAPID project will utilize the novel technique of single particle Inductively coupled plasma mass spectrometry (ICP-MS) to detect and quantify the nanoparticles present in deionized water suspensions. The research team will investigate effects of particle size on metal bioaccessibility by performing single particle ICP-MS analysis as part of dissolution experiments using simulated lung fluids. Timely analysis of the burned materials will advance knowledge of metal speciation in post-fire debris and may inform a responsible remediation effort with respect to human health and environmental impact. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.