Assessing magnetic properties of biomonitors and road dust as a screening method for air pollution monitoring

Particulate matter (PM) pollution is one of the world's most serious environmental challenges. Among PM components, atmospheric heavy metals (HMs) are considered one of the main pollutants responsible for causing significant negative impacts on human health, and ecological quality. This study aimed to assess environmental magnetism as a simple and rapid method that can be used to evaluate heavy metal contamination in urban areas from the relationships between magnetic properties and heavy metal concentrations. For this purpose, road dust and leaf samples of two common evergreen species (Cupressus lusitanica/Casuarina equisetifolia) were sampled simultaneously for 2 years at sites with different levels of traffic pollution. The results found significant statistical correlations between the magnetic properties and the chemical substances of the plants studied, as Fe, Cr and V showed an r ≥ 0.9 and Cr and Zn r ≥ 0.7 with χlf in C. equisetifolia. The frequency-dependent magnetic susceptibility was found to be between 0% and 14% for plants, and 0% and 2% for road dust, suggesting a rather dissimilar particle size distribution for plants, and a less important contribution from the more hazardous ultrafine superparamagnetic magnetite for both. Confirming that magnetic analyses can be used to distinguish different degrees of urban air pollution.