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baie 



DE MORLAIX 



FIGURE 5. Known coastal areas of oil accumulation in sediments. 



BAYS OF MORLAIX AND LANNION (JULY 1978 TO FEBRUARY 1979) 



A survey was undertaken from July 1978 to February 1979 to follow 

 oil degradation within bottom sediments of the Bays of Morlaix and 

 Lannion. In August 1978, specific sampling of some stations was made by 

 the BRGM (Bureau de Recherche Geologique et Miniere) . At these stations 

 (Fig. 6), several-meter-long cores were taken by vibracoring to 

 ascertain the vertical distribution of oil in sediments. 



Oil Pollution in Surface Sediments 



The sedimentary description of sediments coLlected from July 1978 

 to February 1979 is given by Beslier (1981) and Beslier et al. (1981) . 

 The weathering of hydrocarbons in some polluted samples was studied by 

 Boehm et al. (1981). In July 1978, the hydrocarbon concentrations 

 (determinations made on purified organic extracts) ranged from 8 ppm to 

 more than 1,500 ppm. Average concentrations are presented in Table 1. 

 Complete data are given by Marchand and Caprais (1981) . 



We also used the parameter of total hydrocarbons/organic carbon 

 (HC/OC) to demonstrate pollution of surface sediments. This ratio 

 (HC/OC x 10 ) ranged from 48 to 6,065. Marchand and Roucache (1981) 

 showed in a study of another oil spill in Brittany (BOHLEN wreck) that a 



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