Feathers of Feral Pigeons (Columba livia) as Bioindicators of Atmospheric Metal Pollution: A Pilot Study in Kazakhstan

Atmospheric metal pollution in urban ecosystems is a critical global issue. Feral pigeons (Columba livia) serve as effective bioindicators of ambient air quality. This pilot study evaluates their applicability across three contrasting regions in Kazakhstan: Ust-Kamenogorsk (non-ferrous metallurgy), Pavlodar (coal-fired power generation), and Bigash village (rural background). Concentrations of 14 metal(loid)s and 10 rare earth elements (REEs) in feathers were determined via ICP-MS/ICP-OES and analyzed using principal component analysis, hierarchical cluster analysis, and pollution indices. In Ust-Kamenogorsk, high contamination factor (Cf) values for Cd (26.0), Pb (41.2), and As (19.0) indicated ‘very high contamination’ from non-ferrous metallurgy. In Pavlodar, Cf values for Cd (5.0), As (5.0), and Cu (7.3) showed ‘considerable contamination’ linked to coal combustion and oil refining. The total Metal Pollution Index for Ust-Kamenogorsk (11.1) was 4.8 times higher than for Pavlodar (2.3). REE profiles showed a ‘dilution effect’ driven by industrial dust, except for gadolinium, for which a pronounced concentration peak was recorded in Pavlodar. Multivariate statistics confirmed the effectiveness of using pigeon feathers as an integrative tool to differentiate zones of high technogenic pressure. Overall, this pilot study lays the foundation for long-term biomonitoring of the urban environment in industrial centers of Kazakhstan with heavy pollution loads.