Magnetic Assessment of Transplanted Tillandsia spp.: Biomonitors of Air Particulate Matter for High Rainfall Environments

Abstract

Complementary methodologies in air quality monitoring, such as magnetic biomonitoring, are currently implemented since atmospheric particle pollution is a relevant problem for human health and ecosystems. We carried out magnetic biomonitoring using transplanted species of Tillandsia recurvata and T. usneoides to study their retention capacity of airborne magnetic particles AMP, the influence of precipitation, and magnetic properties. Plants of both epiphytic species were exposed for two, three and twelve months under uncovered and covered rain exposure conditions. The mass-specific magnetic susceptibility χ increases for both species over time, mean (s.d.) values of χ = 6.1 (6.4)–47.9 (37.6) × 10−8 m3 kg−1. The comparison of χ between exposure conditions suggests an insignificant rainfall influence on the accumulation/loss of magnetic particles in the studied plants. Magnetic parameters, scanning electron microscopy, and X-ray energy dispersive spectroscopy indicate the presence of magnetite and Fe-rich particles with sizes between <0.1 and 5 µm, a harmful particle category to human health. It is concluded that both species of the genus Tillandsia are efficient biological indicators of AMP and convenient for air particle pollution assessment in high-precipitation environments.