CONICET | Buscador de Institutos y Recursos Humanos

The presence of epiphytic plants in cities is helpful for air quality assessment. Their notable features as airborne pollutants biomonitors allow us to evaluate adverse pollution events. However, the distribution of native species in cities may be scarce and uneven, and the species exposition time is not controlled; hence transplants are often preferred. We present a novel in situ methodology of magnetic biomonitoring using transplants of Tillandsia capillaris and measurements of in situ magnetic susceptibility (κis). Complementary SEM-EDS analysis determined trapped particles' morphology and composition. We propose and develop a protocol for measuring κis directly on species to quantify (sub) micron-sized magnetite particles (Fig. 1). Measuring campaigns were carried out in two midsize cities in Argentina, i.e., Tandil (14 sites) and Olavarría (7 sites), 2-3 individuals of T. capillaris of 5-7 cm in size were transplanted in each site. A total of 53 specimens were measured with a portable susceptibility meter after various exposition periods. The κis value was calculated by averaging ten (n = 10) readings. Two measuring methodologies, a direct-contact measurement (DCM) and a petri-wood measurement (PWM) were tested for samples over time. The κis values presented higher standard deviation values for the DCM (s.d. = 1 x10-6 4 x10-5SI) than the PWM (s.d. = 0.4 x10-7 1 x10-6SI). The wide-range variations (by DCM) seem to be influenced by the sensor-to-plant contact. The PWM evidenced low dispersion results comparable to the instrument sensitivity (1 x10-7 SI). This knowledge is essential to develop more accurate protocols for in situ measurement methodologies, i.e. in situ magnetic biomonitoring, and to understand the epiphytic plants' behavior as biomonitors for air particle pollution.