The degradations observed in these sediments results in : 



- the progressive disappearance of saturated hydrocarbons, principally 

 the normal paraffins ; 



- the disappearance of the light aromatic hydrocarbons ; 



- the oxidation of the polar compounds (esters, acids, etc...). 



The compounds which persist are : 



- the saturated polycyclic hydrocarbons and the heavy aromatics ; 



- sulfurous aromatic hydrocarbons of the thiophenic type ; 



- resins and asphaltenes, resulting in stable metal (nickel and vana- 

 dium) and sulfur contents. 



In the sediments samples in the area of the Aber, terrigenic de- 

 posits are superposed on the Amoco Cadiz crude, resulting in : 



- an increase in polar compounds — resins and asphaltenes. The in- 

 crease in asphaltene contents is due to the presence of pigment 

 (green) of chlorophyllaceous origin ; 



- the appearance of n-alkanes of odd carbon numbers (n-C25 through 

 n-C33) . 



The most striking evolution in the "chocolate mousse" samples is 

 the loss of light hydrocarbons due to evaporation and dissolution. 

 Volatile compounds under C14 were not considered in this report. 



The samples of polluted sand taken from the beaches a year after 

 the accident show a degradation phenomenon principally affecting the 

 saturated hydrocarbons, and among these, principally the n-paraffins. 

 There is an increase in the contents of polar compounds. But our in- 

 formation is not adequate to state at what point in the history of 

 these samples, the degradation was most intense. 



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