STUDIES OF HYDROCARBON CONCENTRATIONS AT THE ILE 

 GRANDE AND BAIE DE LANNION STATIONS POLLUTED 

 BY THE WRECK OF THE AMOCO CADIZ 



Henri Dou, Gerard Giusti, and Gilbert Mille 



Laboratoire de Chimie Organique A, Associe au CNRS 

 n°126, Centre de St. Jerome 

 13397 Marseilles Cedex 13, France 



INTRODUCTION 



A study of the hydrocarbon concentrations in district no. 7 has been made 

 since December 1978 in collaboration with the Marine Station of Endoume (Mes- 

 dames Vacelet, Plante, and Lecampion) . The first series of analyses was made 

 outside of the CNEXO-NOAA framework, while our second study was supported by 

 them. Results of the two studies are herein combined. 



METHODS 

 Nature of the Samples 



Samples were collected at sites indicated in Figure 1. Sample sites A, 

 D, and F are located in a very polluted zone; B, C, and E are located in a 

 zone where the pollution level is lower since a dam was erected under the 

 bridge to prevent the spreading of oil. Subscripts indicate specific areas 

 samples: 1 - marsh, 1 = tidal creek, and 3 = upper mud flat (see Figs. 1 and 

 2). 



Samples were collected in December 1978, March 1979, November 1979, and 

 May 1980, using a plexiglass corer (ID = 26 mm). The 5 mm superficial layer 

 was subsampled with a steel spatula. Sediments were immediately frozen, flown 

 to Marseilles, and kept at -30 C. 



Analytical Techniques 



To yield the maximum amount of information, we have chosen the systematic 

 soxhlet extraction following Farrington's method. This method is expensive 

 and time-consuming but, for the biologists, it is the only one which gives 

 satisfactory results. Moreover, reproducibility was tested several times and 

 was found to be satisfactory. 



To avoid the very long separation of alumina- or silica-packed columns, 

 we developed a micromethod of separation using Sep-Pak of Waters. This rapid 

 technique is described in Analytica Chemica Acta. The general analytical 

 scheme is as follows: 



101 



