Detecting high contributions of primary organic matter to marine aerosol: A case study

Using on‐line High‐Resolution Aerosol Mass Spectrometry, we report submicron organic marine aerosol plume concentrations peaking at 3.8 μg m−3. These concentrations are far greater than previously determined by off‐line techniques and can exceed typical terrestrial concentrations of organic aerosol. The organic mass comprised 77% of the total submicron non‐refractory mass and such plumes were associated with regions of high biological activity and moderately‐high wind speeds over the N.E. Atlantic. High‐resolution mass spectra analysis revealed a unique marine organic aerosol fingerprint, when compared to anthropogenic organic aerosol, and in particular, anthropogenic hydrocarbons. 37% hydrocarbon and 63% oxygenated hydrocarbon speciation was observed for the organic mass, indicating that at least 37% of the organic mass is produced via primary sea‐spray. The hydrocarbon and oxygenated hydrocarbon species were highly correlated (r > 0.99) suggesting a significant, if not dominant, fraction of the oxygenated component is also likely to be sea‐spray in origin.