Oil Spill-Source Correlation by Gas Chromatography: An Experimental Evaluation of System Performance

Abstract

ABSTRACT A simple gas chromatographic method correlates unknown oils in natural waters with possible source oils. Under the operating procedures involved, unique matches are generally achieved without miscorrelations, even when up to 15 oils of the same type (#2, #4, #6 fuel; crudes, etc.) are possible sources. Oil samples are quantitatively characterized by ratios of intensities corresponding to their contents of several components of known geochemical variability and resistance to weathering. The effects of weathering, sample types, and added spill control chemicals were determined by “blind” correlation of 35 artificially weathered oils, each with one of 17 possible sources. Oil type and weathering did not seriously influence spill-source matching success. The presence of highly similar source oils was the major performance-limiting factor. We determined the extent of this limitation, and thereby the probability of successful performance, for collections of oils from Greater New York Harbor products, and from Portland, Maine (crudes: 450 tankers/yr.). The probability that a unique correlation can be reached decreased with increase in the number of oils of the same type which were a priori possible sources and therefore candidates for matching; for the New York Harbor and Portland collections examined success rates were: 1–8 candidate oils, 100 percent; 14 oils, 50 percent; 22 oils, 27 percent.