Altitudinal and Seasonal Assessment of Precipitation Chemistry and Wet Deposition in the Vaz Research Forest, Northern Iran

This study examines the chemical composition of precipitation across altitudinal gradients in the Vaz Research Forest, northern Iran, from 1999 to 2003. Precipitation samples were collected at 300, 1000, 1600, and 2200 m above sea level. Concentrations of nitrate (NO₃⁻), sulfate (SO₄²⁻), chloride (Cl⁻), ammonium (NH₄⁺), calcium (Ca²⁺), and magnesium (Mg²⁺) and their wet deposition values were analyzed. Results indicate that annual wet deposition of most ions decreases with elevation, although anomalies at 1000 m suggest anthropogenic emissions. Precipitation remained slightly alkaline (pH > 7), while nitrogen deposition exceeded critical thresholds for sensitive ecosystems (Pardo et al., 2011; UNECE, 2022). These findings highlight the influence of local human activities on atmospheric chemistry.