Atmospheric Deposition as a Cross-Media Pathway for Aquatic Contamination: Occurrence, Transformation, and Ecological...

Atmospheric deposition is a major cross-media pathway by which contaminants enter aquatic environments, with significant implications for water quality and ecosystem integrity. This review synthesizes current knowledge on the sources, atmospheric transformation processes, deposition fluxes, and ecological and human health risks of atmospheric pollutants reaching water bodies, with an emphasis on linking sources, transformations, deposition, and impacts within a unified framework. Data from the Emissions Database for Global Atmospheric Research indicate that anthropogenic emissions are the dominant source, whereas pollutant fate is strongly shaped by solar radiation-driven photochemistry, ozone oxidation, and radical-mediated heterogeneous reactions that control secondary formation and modify pollutant composition, toxicity, and deposition behavior. Although the relative contribution of atmospheric deposition varies by region and pollutant class, available evidence shows that it accounts for 40%-60% of persistent organic pollutant inputs to rivers and lakes, ~20% of dissolved organic matter inputs to lakes and marshes, 5%-12% of microplastic inputs to the oceans, and up to 24.5% of inorganic compound inputs (e.g., SO_x and NO_x) to rivers and lakes. Once deposited, these contaminants can drive aquatic ecotoxicity and increase human exposure through inhalation, water use, and trophic transfer, contributing to both acute effects and chronic outcomes such as cancer, reproductive disorders, and organ damage. By integrating evidence across multiple pollutant classes, this review highlights atmospheric deposition as a unifying cross-media pathway linking emissions, transformation, aquatic contamination, and risk.