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FIGURE 2. The program of analysis. 



hydrocarbons trapped in the subtidal sediments of the Aber Wrac'h was 

 followed from March 31, 1978 to October 22, 1979 at nine stations 

 (Fig. 3) in the estuary, taking into account the fairly pronounced 

 marine character of the environment and the sandy, muddy, or sandy/ 

 muddy nature of the sediments. 



Over a second period, from January 17, 1980 to June 24, 1980, 

 three study sites, Stations 5, 6 and 8, which were deemed representa- 

 tive of the different evolutionary patterns of the hydrocarbons, were 

 again put into operation. The studies undertaken at these three 

 stations only, are included in this report. To simplify the evolutions 

 observed in the Aber Wrac'h, the figures included here are limited to 

 samplings taken on March 31, 1978, November 22, 1978, June 20, 1979, 

 January 17, 1980, and June 24, 1980. 



Station 5 



A reduction was noted in the pollution of this station, situated 

 in the outer area of the Aber where the marine environment is parti- 

 cularly pronounced (Fig. 4). It was very slight, however, since the 

 concentrations observed in June 1980 were over 670 mg of hydrocarbons 

 per kilogram of sediment. This may be explained by the slightly muddy 

 character of the sediment. 



114 



