Lake Michigan Surface Films: Fatty Acids and Aliphatic Hydrocarbons

摘要

Fatty acid and hydrocarbon contents have been measured in the particulate and dissolved phases of surface microlayer and subsurface water samples collected at 21 Lake Michigan sites. Microlayer concentrations are consistently higher than corresponding subsurface concentrations, and the surface enhancement of both fatty acids and hydrocarbons is greater than that of total organic matter. River-borne materials are important constituents of river mouth and nearshore lake environments as shown by concentration gradients which decrease with distance from shore. These materials are removed from the microlayer and subsurface water by settling particles and are partially replaced by lake-derived organic matter. Concentration ratios of surface-to-subsurface contents become greater towards open lake areas in response to physical factors favorable to microlayer maintenance. Petroleum hydrocarbons are present in some localities and are the result of land runoff and shipping activities.