Assessment of Pb and Mn Accumulation in Marrubium vulgare L. as a Bioindicator and Phytoremediation Candidate in Industrial and Urban Environments of Sétif (Algeria)

Heavy metal contamination has become one of the most critical environmental challenges affecting ecological integrity, soil functionality, and human health. Identifying native plant species capable of accumulating and tolerating toxic metals is, therefore, essential for improving environmental monitoring and supporting sustainable remediation strategies. In this study, we assess the bioaccumulation potential of Marrubium vulgare L., a widely distributed medicinal species, for lead (Pb) and manganese (Mn) across ten industrial and urban stations in Sétif (Algeria). Aerial plant tissues were collected and analyzed using Flame Atomic Absorption Spectroscopy (FAAS). Pb concentrations ranged from 138.82 to 582.54 mg/kg, while Mn levels varied from 3402.94 to 4402.55 mg/kg, both largely exceeding internationally certified limits for plant tissues. Statistical and multivariate analyses revealed pronounced spatial variability for Pb and a more uniform accumulation pattern for Mn, suggesting a combined influence of industrial emissions, vehicular traffic, and the natural geochemical background of the region. UPGMA clustering distinguished two major groups of stations corresponding to differing contamination intensities. Overall, the results confirm the strong capacity of M. vulgare to accumulate high metal loads, highlighting its reliability as a bioindicator of heavy-metal pollution and its promising potential in phytoremediation applications within semi-arid, anthropogenically impacted environments. This work provides relevant insights for environmental monitoring programs and supports the development of future ecological restoration and pollution-mitigation strategies.