Surface active organic material in air over the Mediterranean and over the eastern equatorial Pacific

Abstract

Airborne particulate material was collected on glass fiber filters with high-volume air samplers mounted aboard ships during July 1973, in the Ligurian Sea region of the Mediterranean Sea, and during February 1974, in the Pacific Ocean on a cruise from Panama to Ecuador via the Galapagos Islands. The filters were extracted with chloroform, and the lipid components of the extracts were converted to methyl esters for analysis by gas chromatography. Single fatty components in the range of 12–18 carbon atoms in length varied up to a maximum concentration of 50 ng/m3 of air when expressed as methyl esters. For the Pacific samples the concentration of total organic material extracted by chloroform ranged from 0.08 to 4.02 μg/m3 of air. In order to investigate the possibility of stabilization of fogs by organic chemical films, film pressure versus area isotherms were determined for the surface-active material recovered from each of the Pacific samples. There was not enough surface film-forming material found to coat the droplets of a hypothetical fog in the sampled air, but enough material was found to entirely coat the nuclei associated with a fog. Therefore the initial formation of a fog might be delayed because of a change in the wetability of the nuclei due to the surface film.