Organic films on natural waters: Their retrieval, identification, and modes of elimination

Air-water interfacial films were sampled and subjected to nondestructive analysis by multiply attenuated internal reflection (MAIR) infrared spectroscopy. A field program on Lake Chautauqua in western New York correlated the buildup of oily films over the lake surface with peak boating activity and demonstrated the rapid elimination of such pollutant layers by natural mechanisms. A laboratory program to assess the relative efficiencies of various processes for film degradation included studies of the influence of ultraviolet-visible irradiation, capillary-wave action, bacterial activity, and bubble breaking. Bubble breaking and its concomitant ejection of film fragments into the air was by far the most efficient process, especially when simultaneous irradiation accelerated the formation of polar moieties in the films. Chemical fractionation by this mechanism has also been demonstrated, with the more polar organic components and their associated inorganic elements being stripped from the interface preferentially. Thus, air-sea interfacial films are implicated in sea-to-air material transport and in the chemistry of marine aerosols.