PAH refractory index as a source discriminant of hydrocarbon input from crude oil and coal in Prince William Sound, Alaska

Geochemical correlation and differentiation of hydrocarbons from crude oils and coals is difficult. The complex mixture of the hydrocarbon constituent s and the dynamic nature of these constituents in the environment as they w eather contribute to this difficulty. A new parameter, the polycyclic aroma tic hydrocarbon (PAH) refractory index, is defined here to help in this cor relation. The PAH refractory index is a ratio of two Of the most refractory constituents of most crude oils, namely triaromatic steranes and monomethy lchrysenes. These are among the most persistent compounds in oil after depo sition in the environment and thus: retain reliably the signature of the or iginal petroleum input. This index is utilized in Prince William Sound (PWS ) to differentiate three different oils, as well as to provide evidence tha t coal, not oil, is the dominant source of the PAHs which are prominent con stituents of marine sediments from PWS and the Gulf of Alaska. (C) 1999 Els evier Science Ltd. All rights reserved.