ABSTRACT
Fluorometry has been relied upon to provide a rapid assessment of oil dispersion in the water column, and various commercial fluorometers are available for in-situ usage. Concerns have been raised recently in regard to two issues of oil fluorometry: 1) existing commercial fluorometers might not be in the optimum range for oil detection, and 2) fluorometry alone might not be a sufficient indicator of oil dispersion at sea as weathered oils are likely to have too low fluorescence signatures for detection. Herein, two oils of different chemical properties (i.e., Alaska North Slope and Cold Lake Summer Blend dilbit) were selected at both fresh and insolation-weathered states. The oils were used to create both natural and chemical (i.e., using dispersant) dispersion in artificial seawater. For the latter, Corexit9500A was used at a dispersant to oil ratio (DOR) of 1:20. The fluorescence of the oils was measured at three loading concentrations using three commercial fluorometers and a fluorescence spectroscope (Horiba Aqualog) that scans the whole range of oil excitation-emission matrix. The results elucidate ranges of optimum performance for various in-situ fluorometers.