Combined magnetic, chemical and morphoscopic analyses on lichens from a complex anthropic context in Rome, Italy

Magnetic Emissions from Brake Wear are the Major Source of Airborne Particulate Matter Bioaccumulated by Lichens Exposed in Milan (Italy)

“…The results of bioaccumulation showed that Milan is quite homogeneously affected by high deposition loads of elements such as Cr, Cu, Fe, and Sb; some more spotted peaks emerged also for Pb. This outcome is consistent with other lichen biomonitoring studies in urban areas of Italy [37,[39][40][41][42]. The results are indicative of a common origin of pollutants from non-exhaust sources of vehicular traffic, such as brake abrasion.…”

“…The transplants markedly overlap the "brake" samples and fall at the lower right end of the cluster defined by the particles accumulated on leaves and filters, in a region of the plot falling in-between the theoretical trends for SD-MD and SD-SP pure magnetites, far from "diesel" and "gasoline" exhausts, which instead follow the theoretical trends for mixtures of single domain (SD) and multidomain (MD) magnetites. This result is at variance with the observations of [37] for combustion dusts accumulated by lichens exposed in an area subjected to arsons, where the magnetic mineralogy corresponded to magnetite-like minerals in PSD magnetic domain state/grain size, similarly to the diesel exhaust emissions in [32].…”

“…The range of the magnetic susceptibility values (7.8 to 35.8 × 10 −8 m 3 kg −1 ), when compared with previous studies on transplanted lichens, is indicative of a notable concentration of magnetic minerals and, consequently, of iron-rich bioaccumulated particles. Transplants of the lichen Pseudovernia furfuracea exposed for 4 months in a complex and heavily polluted area, ranged from 7.1 to 17.1 × 10 −8 m 3 /kg −1 [37]. Transplants of the same lichen species exposed for 2 months in an industrial area showed values in the range 0.4 to 7.4 × 10 −8 m 3 /kg −1 [46].…”

“…The shape and the recurrent inclusion of various elements other than Fe make these magnetic particles different from natural stoichiometric magnetite. Most morphologies were irregular, with rough and/or rounded and frictional surfaces, dissimilar to the spherical shapes of industrial fly ashes originated by the combustion of black and brown coal (e.g., [33][34][35][36]) or waste electrical and electronic equipment [37]. Figure 7 shows the relationships between magnetic susceptibility and element concentrations, along with the 95% credible intervals (95CIs) of the R 2 values.…”

Negative correlation between concentration of iron oxides and particulate matter in atmospheric dust: case study at industrial site during smoggy period

“…Magnetic properties of tree leaves as biocarriers of the deposited atmospheric dust have been investigated in relation to air pollution by many authors (Hofman et al, 2017;Jordanova et al, 2010b;Jordanova et al, 2003;Kardel et al, 2018;Kardel et al, 2011;Kardel et al, 2012;Maher et al, 2008;Matzka and Maher, 1999;Mitchell and Maher, 2009;Mitchell et al, 2010;Moreno et al, 2003;Rodriguez-Germade et al, 2014;Sagnotti et al, 2009;Zhang et al, 2006). There are also numerous studies on magnetic properties of tree needles (Jordanova et al, 2010;Lehndorff et al, 2006;Urbat et al, 2004), tree barks, rings or branches (Brignole et al, 2018;Chaparro et al, 2020;Vezzola et al, 2017;Wuyts et al, 2018;Zhang et al, 2009;Zhang et al, 2008), lichens, in situ or transplanted (Chaparro et al, 2013;Kodnik et al, 2017;Marie et al, 2016;Marie et al, 2018;Paoli et al, 2017;Salo et al, 2012;Winkler et al, 2019Winkler et al, , 2020, and moss and transplanted moss bags (Fabian et al, 2011;Limo et al, 2018;Salo et al, 2012Salo et al, , 2016aSalo et al, , 2016bMakinen, 2014, 2019;Vukovic et al, 2015a;…”