<i>Tillandsia usneoides</i> for Atmosphere Composition Biomonitoring: A Cross-Validation Study

Tracking for particulate matter (PM) contamination is a tedious task that requires sophisticated samplers powered by electricity. Biomonitoring strategies have been developed to assess PM contamination. Among them, epiphyte plants are widely utilized due to their reliance on atmospheric inputs for nutrition. However, robust assessment of the effectiveness of such strategies remains limited. This study aimed to assess whether Tillandsia usneoides can accurately characterize PM contamination across four sites in a former French mining district over one year. Comparisons were made between (i) PM10 samplers capturing PM with an aerodynamic diameter < 10 μm and (ii) T. usneoides, which is assumed to accumulate all deposited particles (both wet and dry). The finding reveals that atmospheric composition measured by PM10 samplers and T. usneoides is consistent for 14 of the 27 elements analyzed. However, elements related to (micro)nutrients or those chemically similar to nutrients (Na, Rb, Sr), showed no significant or positive correlation. While epiphyte plants offer a cost-effective and efficient tool for (bio)monitoring PM composition, results involving elements playing a role in plant metabolism should be interpreted with caution. Further research should better highlight the mechanisms governing the complex interplays between PM properties, epiphyte microstructure, metabolic responses, and abiotic factors.