Local honey reflects environmental changes in metal concentrations and lead isotope ratios during COVID-19 restrictions in Brussels, Belgium, and Vancouver, Canada

Effective methods for measuring sudden environmental changes are crucial for understanding how cities respond to shifts in human activity. This study examines atmospheric metal outputs during the COVID-19 restrictions using honey samples collected from three land use types in Brussels Capital Region (BCR), Belgium, and Metro Vancouver Regional District (MVRD), Canada to study changes as the result of restrictions. By comparing these cities with distinct sizes, ages, and structures, we assess how urban environments responded to pandemic-induced restrictions. We present honey samples, analyzed for metal concentration and Pb isotope ratios, to provide insights into the impacts of reduced human activity in different land use types. In BCR, significant increases of Al, Cd, Cr, Cu, Fe, Ni, Pb, Ti, and V were observed in suburban sites, while in MVRD, significant decreases of Cr, Pb, Sb, Ti, and V were observed in suburban sites. The increase in metal concentrations in BCR suburban sites indicates a shift in metal emission patterns due to changes in human activity during the restrictions. Conversely, the decrease in metal concentrations in MVRD suburban areas aligns with expectations of reduced pollution during restrictions. Pb isotope ratios of BCR vary more widely and do not show any spatial trends by land use, suggesting that Pb concentrations in BCR may be more homogenized. In MVRD, significant differences in ²⁰⁸Pb/²⁰⁶Pb were observed during the restrictions, wherein honey sampled from rural sites had more radiogenic (lower ²⁰⁸Pb/²⁰⁶Pb) Pb isotope ratios. This difference suggests that honey may be more sensitive to Pb isotope ratio changes in environments with a less extensive history of metal use, such as rural British Columbia. This research demonstrates the potential of honey as a biomonitor for sudden environmental shifts. This study contributes to a global geochemical honey database, enabling tracking of environmental trends across diverse urban settings worldwide.