Snow-Based Assessment of Atmospheric Trace Metal Deposition on the Sinop Coast (Türkiye): Source Signatures and Air-Quality Monitoring Relevance

Snow cover is an effective seasonal matrix for evaluating atmospheric deposition in coastal environments. This study assessed trace-metal deposition in snow samples collected from six stations along the Sinop coast, Türkiye, during a winter campaign in 2025. Twenty-six elements were measured by ICP-MS and interpreted using concentration ranges, multivariate statistics, enrichment factors, ecological-risk indices, and supplemental screening-level exposure metrics. Major marine and crustal elements varied widely: Na ranged from 1325.56 to 5222.58 µg L⁻¹, Mg from 223.43 to 727.86 µg L⁻¹, Ca from 671.42 to 6997.55 µg L⁻¹, and K from 195.45 to 3190.34 µg L⁻¹. Trace-metal levels were generally low, with Pb ranging from 0.50 to 1.38 µg L⁻¹, Cd from 0.05 to 0.13 µg L⁻¹, Hg from 0.05 to 0.06 µg L⁻¹, Cu from 3.69 to 7.89 µg L⁻¹, and Zn from 35.88 to 110.73 µg L⁻¹. Correlation and PCA patterns indicated mixed marine, lithogenic, and localized anthropogenic influences, especially through Na-Mg, Sr-Ca, Fe-Ti-Mn, and Zn-Cd-Pb associations. Pollution indices remained low, with HMEI values of 0.12–0.49, HMPI of 1.99–4.11, and RI below 150 at all stations. HI_total was also below 1 across the study area. Overall, the findings indicate a low winter atmospheric metal burden and demonstrate the usefulness of snow cover as a passive sampler for coastal air-quality monitoring in the Black Sea region.