Abstract

Introduction Wildfires can substantially alter soil geochemistry in fire-prone environments, yet their influence on inorganic nanoparticles (NPs) remains poorly constrained.Methods This study investigated nanoparticle dynamics following a wildfire in the Cantillana Reserve (central Chile) by combining field sampling, controlled combustion experiments, bulk geochemical analyses, and single-particle ICP-TOFMS.Results Fire exposure caused a marked increase in nanoparticle number concentration, reaching up to 1.4 & times; 109 particles per gram in ash-enriched soils, together with a shift from predominantly monometallic to multimetallic particles (e.g., Fe-Mn-Ti and Fe-Zn). Comparable patterns were observed in laboratory heating experiments, supporting temperature as a key control on elemental redistribution, reduction, and volatilization. Fire-affected samples also contained smaller nanoparticles enriched in Pb and Zn, suggesting enhanced post-fire metal mobility and potential environmental exposure. In addition, bimetallic nanoparticle ratios such as Fe/Mn and Fe/Zn may serve as geochemical indicators of wildfire severity.Discussion Overall, the results show that wildfire can strongly modify nanoparticle abundance and composition, and that nanoscale characterization provides useful insight into post-fire geochemical transformations.