Baseline atmospheric deposition of mercury in a caribbean industrial-coastal area: A case study from Cienfuegos Bay, Cuba

The Greater Caribbean remains a critical data gap in the understanding of global mercury (Hg) cycling, particularly in tropical coastal-industrial environments. To address this gap, this study provides the first long-term and spatially resolved assessment of atmospheric Hg deposition in Cuba, a signatory of the Minamata Convention. Deposition fluxes were measured at 14 sites across the industrial-coastal region of Cienfuegos between 2005 and 2018. Spatial analysis revealed pronounced heterogeneity, with hierarchical cluster analysis identifying four distinct deposition regimes ranging from regional background conditions to localized industrial hotspots. Temporal analysis at a reference station showed a significant increase in Hg deposition between 2005 and 2010 (p < 0.05), followed by stabilization after 2016, coinciding with major changes in local industrial activity, including cement production, thermoelectric power generation, and oil refining. A baseline for atmospheric Hg deposition in Cuba was established for 2016–2018 (median: 0.0314 μg Hg m −2 d −1 ; interquartile range: 0.0151–0.0486 μg Hg m −2 d −1 ). The results demonstrate that atmospheric Hg deposition in tropical coastal-industrial regions is strongly controlled by the superposition of regional background inputs and localized anthropogenic sources. These findings provide a critical baseline for evaluating emission reduction strategies under the Minamata Convention, contribute to reducing global data gaps in underrepresented regions, and support the improvement of Hg biogeochemical models. • First atmospheric Hg deposition baseline established for Cuba. • Hierarchical clustering showed four groups with clear Hg gradients. • Industrial reactivation increased Hg fluxes from 2005 to 2010. • Cement plant and power station areas identified as Hg hotspots. • Results support national compliance with the Minamata Convention.