Comparative Bioaccumulation of Heavy Metals in Two Bioindicator Lichen Species: Implications For Air Quality Biomonitoring

Abstract

Atmospheric deposition of pollutants, such as heavy metals, has detrimental effects on human health and disrupts the balance of terrestrial ecosystems. Assessing metallic element pollution in the city of Djelfa can be achieved through lichen bioaccumulation, which constitutes an excellent tool for air quality biomonitoring. This study analyzes atmospheric metallic contamination in this region using two species of crustose epiphytic lichens, Xanthoria parientina (Xpa) and Physia aiplioide (Pai). The results reveal significant multi-source pollution, associated with road traffic, industrial activities, and incineration, with a marked presence of 16 heavy metals, including iron (Fe), bromine (Br), cobalt (Co), rubidium (Rb), barium (Ba), and arsenic (As). The comparative approach highlights the key role of the species in bioaccumulation: Xpa emerges as a more effective and sensitive bioindicator than Pai for monitoring metallic deposition, due to its higher accumulation capacity. The combined use of both species would thus allow for a more comprehensive and nuanced picture of air quality, distinguishing chronic contamination from acute pollution episodes.