<p>Atmospheric deposition (AD) plays a critical role in nutrient inputs to ecosystems, especially in regions with extensive agriculture and growing environmental pressures. This study synthesizes published ion deposition data from four long-term monitoring sites in the Río de la Plata Basin, compiled from Carnelos et al. (Biogeochemistry, 144(3), 261–271, 2019, Water, Air, &amp; Soil Pollution, 235(187), 1–17, 2024,&#xa0;Atmospheric Environment, 345(January), 2025) and Michel et al. (RP RainNet: The Rio de la Plata atmospheric deposition network. 2010. Evaluation of a new collector design and first year’s results. Metting of the Americas.Iguazu, Brazil, 2010). Only peer-reviewed studies with standardized wet/dry deposition measurements and complete ionic analyses were included, ensuring comparability across sites. Eight major ions (Na⁺, Cl⁻, Mg²⁺, Ca²⁺, K⁺, SO₄²⁻, NO₃⁻, NH₄⁺) were analyzed at four long-term monitoring sites. The analysis revealed three distinct ion groups based on origin and deposition dynamics. Marine-derived ions such as Cl⁻ and Na⁺ dominated in coastal areas and were primarily deposited via rainout, reflecting long-range aerosol transport and cloud scavenging. Terrestrial ions including Ca²⁺, NH₄⁺, and NO₃⁻ were mostly deposited inland, with washout as the main or substantial pathway, and originated largely from soil dust, fertilizer volatilization, and combustion emissions. A third group, Mg²⁺, K⁺, and SO₄²⁻, exhibited intermediate behavior, with mixed or variable origins and balanced contributions from rainout and washout. Total deposition fluxes varied considerably by ion and site, ranging from as low as ~ 0.6&#xa0;kg&#xa0;ha⁻¹&#xa0;yr⁻¹ for Mg²⁺ to as high as ~ 21&#xa0;kg&#xa0;ha⁻¹&#xa0;yr⁻¹ for Cl⁻. The synthesis highlights the importance of regional emission sources, particularly agriculture, biomass burning, and fossil fuel use, and provides a novel framework for evaluating ion-specific deposition patterns in South America.</p>