Magnetic Biomonitoring Using Native Lichens: Spatial Distribution of Traffic-Derived Particles

Abstract

Air pollution has become a subject of extensive study of several disciplines and it is identified as one of the most damaging factors for the ecosystem and human health. In urban areas, particle emission can be found in suspension and therefore a portion of them is inhalable for humans, or deposited on streets and several surfaces, including lichen’s thallus. We studied particulate matter (PM) (by traffic emission) accumulated in native lichens Parmotrema pilosum in order to carry out a magnetic biomonitoring over 2016 and 2017. For this purpose, the environmental magnetism method was complemented with inductively coupled plasma optical emission spectrometry, scanning electron microscopy, and geostatistical methods. The accumulated iron oxides on lichen’s thallus include potential toxic elements, such as Ba, Cr, Ni, and V. Fe-rich particles related to vehicle emissions correspond to (ultra)fine magnetite of inhalable sizes (PM2.5). Our results indicate a relation between concentration of magnetic particles and areas with high traffic, as well as the influence of rainfall on magnetic PM records. Magnetic biomonitoring is validated as a low-cost and complementary methodology to determine levels of air magnetic PM pollution in cities.