31-03-78 



L 



22-11-78 



20 - 06 - 79 



17- 1-80 



3331 



Ll%, 



M_J^O, 



% 



24 6 80 



'-jU^i 



"X 



CG 



STATION G 

 FIGURE 12. Evolution of the saturated hydrocarbons. 



Examination of the chromatograms of the "saturated" fractions 

 shows a quantity of biogenic hydrocarbons of terrestrial origin which 

 is not negligible, and which is characteristic of the upstream sta- 

 tions on the Aber which receive large quantities of deposits from the 

 soils. The distribution of n-alkanes is in fact typical of that ob- 

 served in the extracts from recent sediments in the predominance of 

 odd-carbon-numbered n-alkanes from n-C25 through n-C35 (Fig. 16). 



These quantities of biogenic hydrocarbons present in the ali- 

 phatic hydrocarbons are demonstrated in the ratio R29-31 developed 



124 



