401 



6 



Figures 8a and 8b show the condition of the metallic end of the drum. 

 The mud line runs between the two arrows from upper right to lower left of 

 Figure 8a, the portion to the upper left having been buried in the bottom 

 sediments. The corroded area in the center of the metallic end is shown in 

 Figure 8b. This appearance is typical of a painted steel surface in the early 

 stages of seawater corrosion. The small white streaks near the lower rim of 

 the metallic end as seen in Figure 8a were the only macroscopic biological 

 growths that were found attached to the drum. They were sampled and 

 identified as polychaete tubes under separate contract by Dr. Donald Reish of 

 California State University. 



There was very little corrosion below the mud line. Where corrosion did 

 take place, it appeared to be highly localized as in Figure 9. Instead of 

 being spread uniformly over the surface, the corrosion took place in the form 

 of broad shallow pitting (see arrows) . It is estimated that the depth of 

 attack was 0.2 to 0.5 mm. As there were no corrosion products associated with 

 these pits upon recovery of the drum, one can only assume that the products 

 were scraped off as the drum dragged along the bottom. This is a reasonable 

 assumption as this portion of the drum was below the mud line prior to 

 recovery. 



3.2 Chemical Analysis 



The pH of the corrosion products was measured with pH indicating paper at 

 several locations both above and below the mud line. The pH was generally 



