Marine oil pollution index

A Marine Oil Pollution Index (MOPI) is presented to characterize the hydrocarbon burdens of marine tissues or sediments. The index incorporates the ratios of unresolved to resolved components, even n-alkanes to odd n-alkanes, and branched hydrocarbons to n-alkanes, plus the total recoverable aliphatic and aromatic hydrocarbon concentrations from gas chromatographic analysis, to yield a single value that can be used to compare the relative magnitude of oil contamination in a series of tissue or sediment samples. Several examples of tissue samples from the intertidal mussel Mytilus californianus are presented, along with results from the 1975-78 BLM Southern California Baseline Study and MMS-sponsored Georges Bank Monitoring Program, to demonstrate the usefulness of generating single index values for time-series or spatial trend analyses. MOPI values calculated for analyzed tissue samples reflect varying degrees of exposure, ranging from pristine to heavily petrogenic conditions. A MOPI value calculated for a drilling fluid sample containing diesel oil residues also reflects the heavily petrogenic contamination.