Urban and suburban's airborne magnetic particles accumulated on Tillandsia capillaris

Abstract

Air particle pollution is a current issue that can cause adverse problems to human health and the urban environment. A fraction of these emitted particles is magnetite and iron-rich materials, which may be accumulated by biological indicators and effectively characterized by environmental magnetism methods. Thus, we studied this emitted particle fraction using the epiphytic species Tillandsia capillaris growing in northwestern Argentina’s urban, suburban, and rural areas. The accumulated airborne magnetic particles’ properties revealed valuable information regarding potentially toxic elements, magnetic mineralogy, sizes, morphology, and concentration. Magnetite was detected in samples from all studied areas, and its remanent coercivity values (Hcr = 32.1 – 42.6 mT) in (sub)urban sites are similar to other reported cities in Latin America. The concentration of these airborne magnetic particles AMP varied between urban sites (mean and (s.d.) values of in situ magnetic susceptibility κis = 16.2 (9.4) ×10-6 SI, and specific magnetic susceptibility χ = 61.9 (31.4) ×10-8 m3kg-1) and suburban sites (κis = 13.9 (9.9) ×10-6 SI, and χ = 43.9 (32.2) ×10-8 m3kg-1), and it was distinctively higher than in clean sites. The spatial distribution of AMP was analyzed using a geostatistical model for the concentration-dependent magnetic parameter κis, which showed zones with high magnetic particle accumulation associated with vehicular traffic in the city and industrial emission in a suburban site. Among concentration-dependent magnetic parameters, the κis is recommended for magnetic biomonitoring because Tillandsia species’ individuals are not processed for laboratory measurements, preserving them and allowing us the possibility of measurements over time.