390 



R. J. Barsdate et al. 



soaked with oil were found some 20 m from the polygon. Through late 

 June and early July, 1971, some floating oil was still visible (Figure 9-1) 

 and the oil odor was evident. By mid-July, the thin film of oil surrounding 

 the heavy accumulation along the west side had changed from a typical oil 

 slick to a thin brown scum. At the same time, the thick accumulations 

 began to sink, and became attached to the plant litter in the Carex bed. 



A rough determination of the quantity of oil remaining in July 1971 

 revealed that at least half of the oil was still present. This was measured 

 from aerial and ground observations of the area covered by the heavy 

 accumulation of oil, the oil slick, and the light scum. Samples were then 

 taken 0.5 m to either side of the division between the light and the heavy 

 accumulation to obtain an average weight of oil for each area. 

 Approximately 150 m^ of the total area was covered with oil weighing 

 greater than 2 kg m "^ and about 190 m^ with oil weighing less than this. 

 These values included the oil attached to the vascular plants and litter. 

 This attached oil made collection and extraction of the oil very difficult so 

 there may well be a large error associated with this estimate. Certainly a 

 lot of the oil was still present nearly 1 year after the spill, for a minimum 



E 

 u 



a 



« 



O 



10 



e 



7 6 5 4 3 2 10 



Distance From Shore, m 



FIGURE 9-2. Temperature (°C) and oxygen concentrations (mg O2 

 liter') in Ponds E and C, 23 July 1970. 



