Mosses are well-established bioindicators for atmospheric pollution due to their remarkable capacity to accumulate airborne contaminants. This study evaluates atmospheric heavy metal deposition in the Karabakh region (Azerbaijan) using Leucobryum glaucum as a bioindicator species. Two complementary biomonitoring approaches were applied: (A) passive sampling with native moss and (B) active moss bag exposure using commercially sourced material. Sampling was conducted across eight locations: Shusha, Karkijahan, Khankendi, Khojali, Asgaran, Vang, Kalbajar, and Agdere. Concentrations of Pb, Cd, Cu, As, and Zn were determined by inductively coupled plasma mass spectrometry (ICP–MS) following a 59-day exposure period.

The results revealed consistently higher heavy metal accumulation in native moss compared to moss bags, indicating its superior efficiency for long-term atmospheric monitoring. Elevated arsenic levels were observed in Karkijahan (3.50 mg kg⁻¹), while lead concentrations peaked in Agdere (0.82 mg kg⁻¹). Zinc and copper were notably higher in Shusha (89.6 mg kg⁻¹ and 378.5 mg kg⁻¹, respectively), identifying potential local pollution hotspots. These spatial variations likely reflect differences in emission sources, atmospheric transport, and local environmental conditions.

The study demonstrates the effectiveness of moss-based biomonitoring in assessing regional air quality and detecting heavy metal gradients. Such approaches provide an essential, cost-efficient tool for environmental surveillance and sustainable regional management. Future investigations should integrate long-term monitoring and species-specific calibration to improve quantitative accuracy and ecological interpretation.