Trace metals are enriched in the surface film (SF) in freshwater and marine environments as compared to bulk water. Contributions to the metal burden of the SF are derived both from atmospheric fallout and in-lake bubble-scavenging processes. A significant fraction of the Cu, Cd, Pb, and Zn in southern Lake Michigan SFs is derived from aerosol deposition. Geochemical analysis of aerosol, SF, and bulk water of Lake Superior strongly suggest that (1) most of the Fe, Mn, Ca, Pb, Cr, Zn, Cd, and Ni in the SF is derived from in-lake processes; and (2) enrichment of Cu, Pb, Zn, and Cd in lake aerosol is partially a result of bubble-bursting at the air-water interface. Estimated metal residence time in the SF may be on the order of minutes. Although the total quantity of metal in the SF represents a negligible fraction of the total water burden, the metal accumulation and enrichment at the air-water interface without geochemical/physical controls (i.e., precipitation, sedimentation) in a biologically-active regime suggests its importance in biotic uptake and possible direct introduction into the food chain.