ABSTRACT
The dispersed oil concentrations in sand from three San Francisco area beaches have been measured over a 143 day period following an 840,000 gallon bunker fuel spill in San Francisco Bay. The dispersed oil remaining within the beaches after cleanup was extensively weathered while visible oil globules exhibited only minor weathering. Elevated levels of chloroform-extractable material were observed at two sampling locations following the spill. The background levels of chloroform-extractable materials determined from log-normal distribution analysis were ten-fold higher on bay beaches than on ocean beaches. Laboratory experiments indicated that in a beach system evaporation, dissolution, and microbial degradation combine to remove the lower molecular weight fractions of bunker fuel. A major effect of the beach is to disperse the oil. This dispersal has been shown to greatly enhance the effect of dissolution on the composition of bunker fuel. While the effect of exposure to water on the composition of a bunker fuel slick is minimal, significant amounts of the lower ends of bunker fuel (which is highly dispersed) in a sand column are removed by dissolution.