Magnetic properties of Tillandsia recurvata L. and its use for biomonitoring a Mexican metropolitan area

ANA G. CASTAÑEDA MIRANDA; CHAPARRO MARCOS A. E; CHAPARRO MAURO A. E; BÖHNEL HARALD N.

ECOLOGICAL INDICATORS

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2016 vol. 60 p. 125 - 136

1470-160X

Some epiphytic species accumulate airborne particles and are suitable biological indicators for monitoringurban and industrial pollution. The species Tillandsia recurvata L. was studied as a monitor of air pollutionin an urban area from Mexico. Individuals were collected in 25 sites which are exposed to differentpollution degree and sources.The magnetic particle concentration, particle size, and mineralogy were determined and comparedwith chemical contents for all samples. The highest values of magnetic concentration dependent param-eters were observed in industrial and heavy traffic sites (e.g., mass specific magnetic susceptibility ofup to 171.5 × 10−8m3kg−1). In contrast, sites with low or without vehicular traffic reached low values(e.g., mass specific magnetic susceptibility of down to 1.8 × 10−8m3kg−1). The integrated magnetic anal-ysis (King?s and Day?s plots, remanent magnetization parameters and thermomagnetic measurements)revealed the presence of ferromagnetic minerals, mostly magnetite-like with fine grain sizes (0.1?1 m)and subordinate presence of high-coercivity minerals. Selected samples were observed by SEM and EDSanalysis and revealed the presence of Fe-rich particles, as well as trace elements, among others, As, Sb,S, Cr, Mo, V, Zn, Ba, Hg, Pt and Cu. Most of the elements detected by EDS were also quantified by ICP-MS measurements.Multivariate statistical analyses prove a high correlation between magnetic parameters and elements,as well as allow us classifying sites in clusters (fuzzy c-means clustering) with different pollution degree.These results demonstrate the usefulness of the species T. recurvata L. as a passive pollution monitor,with an affordable and immediate application. This species is abundant not only in Mexico, but also inother cities from America.