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SUGAR REEF 





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Figure 2-1. — Station sites at whkh water samples and bivalves were collected during cruises on 17 and 18 March 1978. The Ocean 250 



was grounded on Watch Hill Reef. 



Table 2-1. — Components of the Ocean 250 gasoline tentatively identified 

 by mass spectrometry. 



Peak number 



Molecular weight 



Compound 



1 



106 



C : -benzene 



2 



106 



C:-benzene 



3 



106 



C. -benzene 



4 



120 



C,-benezene 



5 



120 



Cj-benzene 



6 



120 



C, -benzene 



7 



120 



Cj-benzene 



8 



120 



Cj-benzene 



9 



120 



Ci-benzene 



10 



118 



Indane 



11 



134 



C. -benzene 



12 



128 



Naphthalene 



13 



142 



2-methyl naphthalene 



14 



142 



1 -methyl naphthalene 



15 



156 



C,-naphtha)ene 



small and interfered only slightly with analyses of the higher 

 molecular weight gasoline compounds. A comparison of the 

 analyses of the gasoline standard diluted in hexane with that of the 

 water-accommodated fraction of the gasoline taken through the 

 analytical procedure showed approximately 70% of the higher 

 molecular weight compounds (i.e., d-naphthalenes) and approx- 

 imately 50% of the lower molecular weight compounds (i.e., 

 C ; -benzenes) were returned. Average recovery for all compounds 

 was approximately 60%. The analyses of water samples in this 

 report, however, were not corrected for these losses in the analytical 

 procedure. 



Gas chromatograms of extracts from the water samples from 

 stations 3, 4, and 7 revealed a pattern of peaks that was qualitatively 

 similar to the patterns from the water-accommodated fraction and 

 the gasoline standards. The water-accommodated fraction, the 

 gasoline standard, and extracts from the station 7 water sample are 

 compared in Figure 2-3. There was, however, an apparent greater 



relative loss of some of the lower molecular weight compounds in 

 the water samples. Gas chromatograms of water samples from sta- 

 tions 1 and 1 1 showed no detectable gasoline compounds, and the 

 sample from station 2 showed only trace levels (Table 2-2). GC-MS 

 analyses of the compounds in water samples from stations 3, 4, and 

 7 showed that these compounds were alkylated benzenes, indane, 

 naphthalene, and alkylated naphthalenes (Table 2-1). 



Table 2-2. — Concentrations of gasoline range hydrocarbons in 

 water samples taken off Watch Hill Reef (Ocean 250 spill). 

 Concentrations were not corrected for losses during extraction 

 or chromatographic procedure. 



Water station no. 



Total gasoline hydrocarbons 

 (Cj-benzenes— Cj-naphthalenes) 



2 

 3 

 4 



7 

 11 



Background value 

 Trace levels (1.0 ppb) 

 3 ppb 

 10 ppb 

 12 ppb 

 Background value 



Extracts of shellfish showed gas chromatographic patterns 

 similar to those obtained from gasoline standards in most samples 

 (Fig 2-4), but interfering peaks were also prominent. GC-MS 

 analyses showed many identical spectra from peaks in extracts of 

 the Mercenaria mercenaria sample and from the gasoline standard. 



Discussion. — Experiments conducted to evaluate the analytical 

 method showed it could consistendy recover and measure most of 

 the gasoline present in water samples (Dimock et al. 1980). The sol- 

 vent peak on gas chromatograms obscured only a small number of 

 gasoline peaks, and procedural blanks showed that interfering 

 material was not introduced by the analysis. The average efficiency 

 of recovery for the procedure was 60%, although it was more effi- 

 cient in recovering the less volatile, higher molecular weight com- 



