Particle size dependence of alkali and alkaline Earth metal enrichment in marine aerosols from Bermuda

Three cascade impactor samples were collected from a 20‐m‐high tower on the southeastern coast of Bermuda. These samples were analyzed for Na, K, Ca, Mg, and Fe by atomic absorption spectrophotometry. When the alkali‐alkaline earth metal concentrations are corrected for a soil‐derived component, utilizing the atmospheric Fe concentrations, Mg, Ca, and Na are found to be present in the same relative abundances as in seawater for all particle sizes sampled. Potassium also shows no deviation from a bulk seawater composition for particles with radii greater than ∼0.5 μm. However, excess K above that expected from either a bulk seawater or soil source is observed on particles with radii less than ∼0.5 μm. While oceanic chemical fractionation processes during bubble bursting may be responsible for this excess small particle K, it is most likely due to long‐range transport of K‐rich particles of terrestrial vegetative origin.