Majdjnum Fluorescence Intensity 



Fluorescence Ratio (RI ) 



Wavelength (\) 



Fig. 2 . Summary of fluorescence analysisofsedimentextraclslrom the study 

 area. 



Polynuclear Aromatic Hydrocarbons (PAH's) 



Quantitative PAH deteiminations revealed that low levels 

 of PAH were detected throughout the study area. Generally 

 total PAH concentrations were less than 100 ppb (Fig. 7). The 

 highest PAH levels were detected in the deeper sections of 

 gravity cores (averages for all samples at a site were used to 

 produce regional maps)(Fig. 8). In general, relative regional 

 anomalies in fluorescence intensity. UCM, and PAH coincide. 

 Background PAH's, composed primarily of nonalkylated 

 analogues, have been ascribed to pyrogenic sources ( Kennicutt 

 & Comet, 1990). Thisisconsistent with much of the low level 

 PAH and fluorescence intensities reported here. Polynuclear 

 aromatic hydrocarbons compositions at locations with total 

 PAH in excess of 100 ppb are more indicative of natural 

 seepage. Macroseepage has been documented to the south and 

 southwest of the present study area. Both oil and condensate 

 seepage was detected and their general locations are consistent 

 with the regional variations observed in the present study 

 (Kennicutt et ai. 1990). 



Biomarkcr Analysis 



The previous reports of significant amounts of unique 

 biologically-derived aliphatic hydrocarbons in the eastern 

 Bering Sea was confirmed. Many of the sediment extracts 

 contain compounds previously identified as olefins. A tetraene 

 (Kovats Index |KI] = 2657). squalene (KI = 2895), and aC30 



bicyclic tetraene (KI = 3027) are believed to be due to inputs 

 from zooplankton and/or phytoplankton. These compounds 

 were detected at most locations though concentrations varied 

 widely. A suite of hopenes, moretanes, and pp-hopanes were 

 present at several locations and appear to represent a recent 

 background biological marker mixture. This background may 

 represent erosionally exposed, in place, sediments or materials 

 from the surrounding land masses that have been transported to 

 the site of deposition (i.e., recycled). The precursor 

 functionalized hopanoids and steroids representative of 

 unaltered biolipids were not determined by the analytical 

 methods utilized in this study. The hopanoid compounds most 

 likely represent early alteration products of biogenic lipids of 

 bacterial and/or algal origin. In contrast to these immature 

 markers, overprinting by 17a, 21 (i hopanes; diasteranes; and 

 steranes (oca and aPP) are evident at sites suspected of 

 containing mature, migrated petroleum (Table 1 ). These 

 mature biomarkers, which are only produced when temperatures 

 are substantially higher than in these near-surface sediments, 

 are present in extracts from a few stations (Table 1 ). These 

 mature petroleum hydrocarbons — derived from a much deeper, 

 higher temperature source — overprint the in situ biological and 

 "recycled" immature lipids. 



Conclusions 



Aliphatic and aromatic hydrocarbons were widely detected 

 at locations sampled in the Bering and Chukchi Seas. The 

 hydrocarbons are a mixture of marine biological debris (bacteria, 

 algae, zooplankton, phytoplankton), terrestrial plant biowaxes 



TABLE 1 



Presence (+, ++, +++) or absence (-) of selected 

 mature biomarkers in Bering Sea extracts. 



Core Triterpanes Steranes Monoaromatic Tiraromatic 

 # (m/z=191) (m/z = 217) Steranes Steranes 



(m/z = 253) (m/z = 231) 



++ 



295 



