Station D, 



This site is subjected to a flowing stream which must have facilitated 

 the deposit of hydrocarbons in large quantity, since between 1978 and 1980, an 

 important increase was measured (95 g in 1978 to 230 g in 1980) . 



Station C« 



This site indicates that substantial biodegradation is in progress. 



Station A, 



In the FA fraction, we again notice the presence of organic compounds 

 which are neither linear nor substituted. The ratio FA 1978/FA 1980 is very 

 close to that of station Al. 



Stations B and E 



These are reference stations in the less polluted zone. Some remaining 

 pollution is visible, indicating that the dam was not able to prevent oil from 

 spreading to this side of the bridge. In 1980 at B_, the chromatogram of the 

 FA fraction did not indicate petroleum type, and there was a return to normal 

 levels. At E. in 1980, some minor petroleum pollution remained. 



Station A 3 



There are large variations in the hydrocarbon concentrations, primarily 

 at the sediment surface. Two separate samplings in 1980 (5 mm depth) yielded 

 0.27 g and 15 g of oil. However, at -10 cm, the values became equal to 0.50 

 g. The analysis of the 15-g fraction shows that linear and substituted 

 hydrocarbons have disappeared. 



Our results are in good agreement with those noted by biologists. The 

 less polluted zones are returning to a normal state, but a seemingly important 

 residue remains in very polluted sites after linear, substituted, and light 

 aromatic hydrocarbons have disappeared. 



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