Magnetic studies of lichens on tree bark as air pollution biomonitors

MARCOS A.E. CHAPARRO; JUAN M, LAVORNIA; ANA M. SINITO

Tandil

Congreso; 2da. Segunda Reunión Bienal de la Asociación Latinoamericana de Paleomagnetismo y Geomagnetismo (LATINMAG); 2011

LATINMAG y UNCPBA

Several lichens were magnetically studied in order to explore their suitability as air pollution  biomonitors. The lichen (on tree bark) samples were collected in urban and industrial sites from Tandil city (Argentina), as well as control (clean) sites. This vegetation involves 11 species, 8 genus and 3 families. The magnetic properties of lichen samples were determined using rock-magnetic measurements: magnetic susceptibility, anhysteretic and isothermal remanent magnetisation. The results showed that magnetite-like minerals are the main magnetic carriers for all sites and samples. However, the concentration varies between clean and polluted sites. In addition, magnetic grain size distribution showed clear differences between sites. The sites affected pollution are  characterised by coarser magnetic grains (0.2-5 μm). The comparison of magnetic properties did not reveal important differences between species. Most of lichens seem to be suitable air pollution monitors, but a couple of them, i.e. Parmotrema pilosum, Punctelia hipoleucites and Dirinaria picta occur more frequently in the area.