Long-term trends in water-soluble ions in aerosols at Urumqi Glacier No. 1: Evidence of increasing dust and alkalinity in Central Asia

Long-term monitoring of atmospheric aerosols is essential for understanding the interaction between natural processes and anthropogenic activities. This study analyzes a 20-year (2002–2022) dataset of water-soluble ions (WSIs) in aerosols collected at Urumqi Glacier No. 1 (UG1) in the eastern Tianshan Mountains, China. Significant increases in calcium ions (Ca 2+ ) and aerosol pH were observed, indicating enhanced dust deposition and a shift toward an alkaline atmospheric environment. Mann-Kendall trend analysis revealed a notable annual increase in Ca 2+ concentration (0.053 μg m -3 , p < 0.001), with Ca 2+ contributing up to 73% of the total ion content during dust-heavy periods (2013–2015 and 2020–2022). Backward trajectory analysis and ion balance calculations identified Central Asian deserts as primary dust sources, while other WSIs (e.g., SO 4 2- , NO 3 - , NH 4 + ) reflect contributions from anthropogenic emissions. These findings highlight the growing influence of transboundary dust transport and its implications for air quality, glacier dynamics, and environmental changes in high-altitude regions. • A 20-year analysis of water-soluble ions (WSIs) in aerosols at Urumqi Glacier No. 1 reveals notable trends in dust deposition and alkalinity. • Increased calcium ion (Ca 2+ ) levels, linked to Central Asian dust storms, indicate a shift towards alkaline aerosols. • Major dust events occurred from late 2013-2015 and 2020-2022, with Ca 2+ accounting for up to 73% of total ions during these periods.