INTRODUCTION 



An anaerobic environment devoid of oxygen and where marine 

 sulfate-reducing bacteria flourish and produce hydrogen sulfide is 

 found in many parts of the world's oceans. These areas are usually 

 found in places where circulation of oxygenated seawater is restricted 

 or reduced such as in harbors and bays (especially in bottom mud) and 

 in basins (bottom waters of the Black Sea). In an anaerobic environ- 

 ment, the sulfate-reducing bacteria utilize sulfates and sulfites in 

 the absence of oxygen during their metabolic process leading to the 

 formation of hydrogen sulfide (rotten egg smell). The anaerobic 

 corrosion of metals exposed in such an environment is widespread 

 and destructive. For example, it is reported that extensive corrosion 

 and deterioration is experienced by pipes, pumps, storage tanks, steel 

 pilings in harbors, mooring chains of buoys, ship hulls, and painted 

 surfaces of metals in such an environment. >' J 



To obtain additional knowledge about what will happen to materials 

 exposed in bottom sediments containing hydrogen sulfide, materials 

 other than metals were exposed in the bottom mud. Reported herein 

 are the test results obtained on various plastic materials, synthetic 

 and natural fiber ropes, electrical cable insulating materials, and 

 a Douglas fir panel which had been exposed in the bottom sediment 

 of Port Hueneme Harbor for a period of one year. 



MATERIALS AND METHOD 



For the long-term exposure tests in the bottom sediments contain- 

 ing hydrogen sulfide, 6x12 inch plastic specimens of varied thicknesses 

 were placed in a rack as shown in Figure 1. The specimens were held 

 in place by four molded, grooved polyethylene insulators and were 

 separated from each other by one inch. The center divider and end 

 plates were titanium alloy 75-A. The rods through the insulators 

 were nickel-copper alloy 400 fastened with nuts and washers of the 

 same composition. Polyvinyl chloride (PVC) washers were used between 

 the metal washers and the end plates. Prior to placing the 6 x 12 

 inch plastic panels in the titanium rack, each specimen (listed in 

 Table 1) was weighed and then tested for hardness with a Durometer 

 Type D or Type A-2 in a temperature and humidity controlled room 

 (75°F, 20%RH). Rope specimens (nylon, polypropylene, polyester, 

 manila, and cotton) with eye-splices were placed around the titanium 

 rack in such a way that the center section of the ropes would be 

 embedded in the mud. The eye-splices were placed in each rope specimen 



MBL/WHOI 



03D1 DDMDE3S 



