A gas chromatographic method of analysis, applicable for all types of petroleum products, has been developed to measure the time dependent extent of evaporation from an oil slick on the open sea. Laboratory calibration tests show the method to have an uncertainty in evaporative weight loss of less than 1 percent. The method has been tested in the Santa Barbara Channel using oil from natural seeps at Coal Oil Point. Under sea state four conditions, this oil lost most of its volatile components in one to two hours. The resulting oil slick residue became sufficiently dense that it could easily enter the water column where it would be subjected to subsurface transport mechanisms. Sea surface roughness was observed to have a significant effect on the rate of evaporation.
1 Present affiliation is Oceanographic Services, Inc. Santa Barbara, California. (To whom correspondence should be addressed.)