Differentiating Natural Volcanic Baselines and Urban Signals in Artemisia and Calamagrostis of the Avacha Agglomeration (Kamchatka).

Establishing environmental reference ranges in volcanically active regions is challenging because lithogenic inputs can overlap with local anthropogenic signals. We evaluated the biomonitoring potential of unwashed above-ground tissues of Artemisia vulgaris and Calamagrostis purpurea in the Avacha agglomeration, Kamchatka, Russia. A total of 88 A. vulgaris and 62 C. purpurea composite samples collected from urban and natural sites in 2017-2023 were analyzed for Zn, Cu, Pb, and Cd by microwave plasma atomic emission spectrometry. Robust statistical approaches were compared to establish species-specific local screening baselines. The median ± 2 median absolute deviation method was selected for A. vulgaris, whereas the iterative 2σ method was selected for C. purpurea. A. vulgaris showed greater concentration variability and a broader range of pollution load index values in urban sites, consistent with greater responsiveness to local environmental heterogeneity. Principal component analysis indicated contrasting associations among Pb, Zn, Cd, and Cu that are consistent with different source-related contributions to the elemental burden. In contrast, C. purpurea showed limited separation between urban and natural sites and its pollution load index values did not provide a consistent urban-natural contrast. The findings support species-specific, locally derived screening baselines for vegetation monitoring in volcanic settings and identify A. vulgaris as the more informative of the two species for detecting localized deviations from regional background conditions.