Abstract
Air pollution affects human health and ecosystems all over the world. However, little attention is paid to its monitoring in tropics, mainly due to the high costs of automated monitoring systems. Biomonitoring may be an alternative, particularly for species of Tillandsia genus, although most species are not yet calibrated for this purpose. Therefore, 1) to determine the biomonitoring potential of T. juncea and T. schiedeana and, 2) to compare the sources and magnitudes of atmospheric pollutants at five urban parks and one rural site in a tropical metropolitan area in Mexico, we measured the elemental and isotopic composition of carbon (C) and nitrogen (N) of four Tillandsia species. The C content averaged 44.6 ± 0.5% (dry weight; p > 0.05). The N content ranged from 0.6 ± 0.1% for the rural site and 2.0 ± 0.1% for an urban site (p < 0.001). The lowest value of δ13C was − 15.9 ± 0.1‰ for T. usneoides for all urban parks, and the highest was − 14.3 ± 0.2‰ for T. juncea in the rural area (p < 0.001). The lowest δ15N of − 12.1 ± 0.2‰ was recorded for T. usneoides in the rural area, and the highest of − 0.5 ± 0.5‰ were recorded for T. schiedeana in one of the urban sites. The four species can be used as biomonitors of C and N emissions, since their specific variations reflect the source and concentration of these atmospheric pollutants. Furthermore, the tillandsias showed that pollution in the metropolitan area is different depending on the activity at each site.