Deep-Ocean Biodeterioration of Materials - Six Months at 6,000 Feet
2007
Muraoka, James S.
The note reports the data obtained after exposing metallic and nonmetallic specimens for 6.3 months on the floor of the Pacific Ocean at a depth of 6,000 feet (Test Site 1). The test specimens were attached to a Submersible Test Unit (STU) that was emplaced August 7, 1968 and retrieved on February 12, 1969. Preliminary examination of the specimens was made aboard ship, and the final examination, tests, and analyses were performed at the Naval Civil Engineering Laboratory. Typical fouling organisms such as barnacles, bryozoa, and mussels were not found on test panels exposed at 6,000 feet, but the surfaces of plastics, metals and ropes were coated with a thin film of microbial slime. Untreated wood and ropes made of natural fibers (cotton and manila) were severely damaged by microorganisms and molluscan borers. Plastic panels which were in direct contact with wood were also affected by the wood borers. Strangely, extensive borer damage to wood panels was restricted to a narrow area extending from the mud-line to a distance of one or two feet above it. Certain chemically treated wood, certain plastics, rubber, and glass were resistant to biodeterioration. Ropes made of polyethylene and polypropylene increased in tensile strength after exposure at 6,000 feet. A limited study on the corrosion of carbon steel and aluminum alloy helped to confirm a long held suspicion that microorganisms might play a role in the corrosion of metals in the ocean.
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