A year-long study of these animals together with supportive measurements 

 from surface sediment and sediment trap samples will be the means to 

 determine the chemical fate of oil from this spill and propose a des- 

 criptive model for the behavior of the oil after the spill. 



11.2 Methods 

 11.2.1 Sampling 



Sampling was carried out by the Swedish scientists from the Asko 

 Laboratory, University of Stockholm, and the Swedish Water and Air 

 Pollution Research Institute (IVL) as part of their ecological impact 

 study. Sampling of Mytilus were obtained periodically from eight of the 

 stations in the study area indicated in Figure 11.1 (B, C, D, E, F, G, 

 I, J). Baseline chemical information was obtained by sampling at 

 stations C, D, and G prior to the oil's landfall. A reference station J 

 adjacent to the biological laboratory on Asko Island was sampled in 

 October of 1978 after it became apparent that the original reference 

 site G was indeed impacted by the oil. 



Macoma samples were obtained in grab or dredge samples taken at 

 nine soft-bottom stations shown in Fig. 11.1 (C, D, 2, 5, 6, 7, 8, 15, 

 20). Station 15 was chosen as the reference station not believed to be 

 impacted by the Tsesis spill. 



At each station at least 5 grams wet weight of Mytilus and Macoma 

 tissue were obtained. Individual specimens measured from 1 to 3 cm and 

 each sample for analysis consisted of 10 to 60 individuals. Samples 

 were frozen after collection and transported using dry ice for preser- 

 vation. 



Sediment traps (see section 4.2.3.5 for details) were deployed at 

 three stations in the area (II, IV, V). Sediment samples were collected 

 as described in section 6.2.1. The collected material was stored frozen 

 prior to analysis. 



11.2.2 Sample Analysis 



Once in the laboratory the shells of the frozen samples were rinsed 

 with distilled solvent. The specimens were then shucked, tissues com- 

 bined and weighed and added to 50 ml Teflon capped centrifuge tubes. 



221 



