Comparative Moss-Bag Biomonitoring of Multielement Signatures in Anthropogenic Underground Systems

Anthropogenic underground systems are challenging to monitor because restricted ventilation, particle retention, resuspension and spatial heterogeneity generate complex elemental patterns. We tested whether controlled active moss-bag biomonitoring supports comparative profiling of multielement signatures in the Historic Silver Mine in Tarnowskie Góry (TG) and the Boryszyn Loop of the Międzyrzecz Fortified Region (MRU). Pleurozium schreberi and Dicranum polysetum were co-deployed at 20 points per site for 90 days; formal between-system inference was restricted to 64 moss-bag samples from 32 underground exposure points. Profiles included Mn, Fe, Cu, Zn, Pb and Hg; Ni and Cd were excluded from continuous inference because of censoring. We analysed net concentration changes relative to corresponding initial values using PCA, PERMANOVA/PERMDISP, mixed-effects models, and Procrustes analysis, with sensitivity analyses based on final concentrations and dominant-element exclusion. Multielement signatures differed between MRU and TG for both biomonitors (PERMANOVA R² = 0.367 and 0.318; both p < 0.001), without significant dispersion differences. MRU showed a stronger Mn signal, whereas TG showed stronger Cu, Zn and Hg signals. Site discrimination persisted after simultaneously excluding Mn and Hg, and cross-species Procrustes correlations were 0.783 and 0.771. These results support moss-bag biomonitoring for comparative multielement profiling, while inference remains limited to deposition-related signals rather than direct source attribution.