Relationship between pelagic tar,fluorescence and biological markers in the South Atlantic Ocean

Surface pelagic tar concentrations in the equatorial South Atlantic Ocean were low (< 0.001 to 14.6 mg m^?2). With one exception, concentrations were less than 0.5 mg m^?2. The tars were characterized by gravimetry, carbon isotopic composition, molecular compositions (gas chromatographically), sulphur content, total fluorescence spectra, and biological marker fingerprints. Most tars exhibited significant amounts of degradation. A total fluorescence technique was used to group the tars into two basic types. One type occurred at low concentrations and appeared to be due to chronic long-term oil pollution in the South Atlantic Ocean. The second group occurred at much higher concentrations and was associated with more coastal-influenced waters. Biological marker (triterpanes and steranes) fingerprints confirmed the fluorescence groupings. Carbon isotopic composition and pristane/phytane ratios exhibited few geographical trends.