heavily oiled samples exhibit an ALK/ISO ratio from 1.7 at station B to 

 2.7 at C, both in early November. Thus, even at the earliest sampling 

 period the petroleum hydrocarbons already exhibit an altered pattern. 



Hydrocarbon GC profiles from particulate material in the water 

 column in the region obtained from sediment trap deployments (see sec- 

 tion on sediment traps) indicate that the oil sampled in the water 

 during the first week in November also has been dramatically altered 

 (see Fig. 11.6), presumably due to microbial degradation. Even the 

 earliest trap samples obtained exhibit a degraded pattern (ALK/ISO = 

 1.0) and within 10 days all of the remaining oil dispersed in the water 

 column has been severely altered (ALK/ISO = 0.1). 



As previously mentioned, the gross hydrocarbon parameters indicate 

 that Mytilus remaining in the region have eliminated most of the initial 

 hydrocarbon burden 1 year after the spill and pre-spill levels are being 

 approached (Table 11.1). However, GC profiles (Fig. 11. 2G) of samples 

 taken from station C in October of 1978 still exhibit significant levels 

 of petroleum hydrocarbons albeit a degraded assemblage consisting mainly 

 of UCM material. 



11.3.1.2 Aromatic Hydrocarbons 



After receiving an initial hydrocarbon tissue burden at levels of 5 

 mg/g to 20 mg/g at the most heavily oiled stations, levels in Mytilus 

 decrease but remain at levels 100 times the background levels of the 

 gross parameters (Table 11.2) 7 months after the spill. One year after 

 the spill levels appear to approach background at all stations except 

 the most heavily impacted station, C. However, a close examination of 

 the gas chromatographic profiles of representative aromatic hydrocarbon 

 fractions throughout the year reveals that residual petroleum material 

 is still present in the tissues one year after the spill (Fig. 11.3). 

 Therefore the gross hydrocarbon parameters (Table 11.2) can be mis- 

 leading without a consideration of both the GC run and the detailed 

 aromatic hydrocarbon composition. The latter was determined by sub- 

 jecting a set of samples for combined gas chromatographic/mass spec- 

 trometric analysis and quantifying individual aromatic compounds which 

 are otherwise obscured in the GC run due to their low levels relative to 

 the entire suite of aromatic compounds. 



233 



