Long-term variations of global antimony (Sb) deposition fluxes and their responses to China's clean air actions

As a priority pollutant designated by the U.S. Environmental Protection Agency (USEPA), antimony (Sb) poses significant risks to global human health. Although the Chinese government has implemented ambitious measures to reduce pollutant emissions, the effects of these actions on global Sb deposition remain unclear. In this study, we developed a global Sb emission inventory and firstly employed the Goddard Earth Observing System-Chemistry (GEOS-Chem) model to simulate Sb deposition fluxes across continents and oceans from 2013 to 2019. Global average total Sb deposition fluxes decreased from 5.8 ± 5.4 (continents) and 4.9 ± 4.6 (oceans) μg/m²/yr in 2013–4.4 ± 3.9 and 3.6 ± 3.1 μg/m²/yr, respectively, by 2019. Spatially, China experienced the most pronounced reduction (-64 μg/m²/yr), followed by India (-5 μg/m²/yr) and North America (NA: −3 μg/m²/yr). In contrast, Sub-Saharan Africa (SS) and Russia showed slight increases in Sb deposition during this period. Over oceans, the most significant declines occurred in East Asian seas, including the East China Sea (ECS: −95 μg/m²/yr) and the Japanese Sea (JS: −45 μg/m²/yr). To evaluate the influence of China's clean air actions, we conducted a sensitivity analysis. The results demonstrated that these measures effectively reduced Sb deposition in East Asia (particularly coastal oceans), with benefits scaling proportionally to emission reduction intensity. For regions farther from China, clean air actions still contributed measurably to local Sb deposition, though the impact diminished beyond a certain threshold (∼20 % emission reduction). These findings underscore the need for region-specific control strategies to mitigate Sb pollution globally.