A 25-Year Assessment of Aerosol Dynamics and Environmental Drivers in Iran’s Lakes and Wetlands

High levels of aerosols in aquatic systems are realized as indicators and agents of environmental degradation. It is imperative that the mechanisms of aerosol contamination in such sensitive habitats be understood for efficient water resource management and conservation of the ecosystem. This paper fills the gap by examining the spatiotemporal features of aerosol optical depth (AOD) over 27 wetlands and lakes in Iran for a 25-year (2000–2024) period. Monthly AOD values were combined with climatic and environmental variables, including wind speed, rain, evaporation, Palmer Drought Severity Index, enhanced vegetation index, normalized difference water index, soil salinity index, and water body coverage. Trend analysis was conducted using the Mann-Kendall test and Sen's slope estimator. The results demonstrated that aerosol concentrations increased by 51.9% over Iran's water bodies in winter, 55.6% in spring, 74.1% in summer, and 66.7% in autumn. On an annual scale, 55.6% experienced an increasing trend, with a significant increase in AODs over Parishan, Miankaleh, Sheedvar, and Gomishan wetlands, as well as Lake Urmia (Z > 1.96). The primary causes of aerosol pollution were identified through machine learning models as changes in: evaporation and rainfall in Parishan; water level and salinity in Gomishan; salinity and rainfall in Miankaleh; vegetation cover and decreased water level in Sheedvar. Based on the total Gini reduction, climatic factors contributed more significantly to air quality degradation in Parishan, Miankaleh, and Sheedvar wetlands (averaging 58%) compared to land-based drivers. Conversely, land-based factors were the primary contributors to air quality decline over Gomishan and Lake Urmia (averaging 68%). These findings are especially beneficial for comprehending the synergy between natural and anthropogenic drivers governing air quality over aquatic ecosystems.