marker compounds, the C3 dibenzothiophenes, and C3 and C4 phenanthrenes, 

 persist but the pyrogenic PAH compounds have replaced any AMOCO CADIZ 

 oil traces at Station 5 in L'Aber Wrac'h. 



The last sampling, June 1981, reveals total disappearance of 

 traces of AMOCO CADIZ aromatic marker compounds at stations 3, 5, and 



7. By June 1981 the only unequivocal presence of AMOCO oil is seen at 

 station 3 in lie Grande, although it has been extremely weathered. 

 Only pentacyclic triterpanes can be linked to the residual AMOCO oil. 

 GC patterns suggest that petroleum still affects stations 4, 6, 7, and 



8, but in only minor quantities relative to other inputs. 



Thus, for the most part, less than three and one half years has 

 been required to allow normal background inputs to resume their sedi- 

 mentary dominance at all but the most heavily impacted (in terms of 

 post cleanup oil concentrations) and lowest energy (i.e. most protected 

 from waves) environments (i.e. station 3 in the lie Grande). 



Further interpretive details are presented in Atlas et al. (1981). 



3.3 Offshore Sediments (Marchand, CNEXO) 



L'Aber Benoit Sediments (Courtot, U. West Brittany) 



In this phase of the analytical chemical program the levels, the 

 persistence, and the precise chemical nature of petroleum hydrocarbons 

 in the offshore sediments of the Bays of Morlaix and Lannion were 

 examined as well as those of L'Aber Benoit sediments (November 1978 

 only) . A summary of the samples analyzed appears in Table 7 and in 

 Fiqure 3.35. 



TABLE 7. AMOCO CADIZ chemistry program; 2. Offshore 

 surface sediments (Marchand) and Aber Benoit 

 sediments (Courtot) . 



Frequency: 



April 1978 6 



July 1978 14 



November 1978 13+7 



February 1979 13 



TOTAL 53 



Locations : 



Aber Benoit (November 1978) 

 Baie de Morlaix 

 Baie de Lannion 



GC/MS : 



Four Time Series (18 Samples) 



62 



