Marine environment temperature

The marine environment is highly aggressive. Materials in marine service are constantly exposed to water, corrosive salts, strong sunlight, extremes in temperature, mechanical abuse, and chemical pollution in ports. This climate is very severe on ships, buoys, and navigational aids, offshore stmctures such as drilling platforms, and faciUties near the shore such as piers, locks, and bridges. 

Three factors influence the rate of corrosion of metals—moisture, type of pollutant, and temperature. A study by Hudson (1) confirms these three factors. Steel samples were exposed for 1 year at 20 locations throughout the world. Samples at dry or cold locations had the lowest rate of corrosion, samples in the tropics and marine environments were intermediate, and samples in polluted industrial locations had the highest rate of corrosion. Corrosion values at an industrial site in England were 100 times higher than those found in an arid African location. 

Spores may be transferred from soil and plants to the sea via rainwater, causing the prevalence in coastal waters of the same C. botulinum types as on the land. Such a correlation was observed in Great Britain, where the type B predominates both in soil and in bottom sediments. Similarly, 71% of fish and bottom-sediment samples collected in southern France were contaminated with type B, while C. botulinum type E was found only in 9.6% of samples (Each et al., 2002). However, it is commonly believed that non-proteolytic type E is characteristic for the marine environment. A distinguishing feature of type E strains is the ability to grow in low temperatures (about 3°C), which are typical for bottom layers of seas and oceans. Moreover, the bottom sediments provide anaerobic conditions for the outgrowth of Clostridium. Therefore, the marine environment promotes C. botulinum type E distribution. This has been further supported by the rate of fish and seafood contamination fish and seafood isolated in many countries are most frequently contaminated with C. botulinum type E (Dodds, 1993 a,b). Furthermore, epidemiological studies have shown that the majority of botulism cases linked to fish and seafood consumption reported between 1950 and 1996 in the U.S. were caused by C. botulinum type E (Centers for Disease Control and Prevention 1998). C. botulinum type F,... 

Fig. 3. The shapes of oxygen isotope zones associated with alteration about sub-volcanic intrusive complexes in a sub-marine environment reflect the local strain, yet still retain zoning systematics. Sizes of intrusions and high-temperature zones correlate approximately with total district tonnage of VMS...

Keith, M. L., and Parker, R. H. Local variation of 13C and 180 content of mollusc shells and the relatively minor temperature effect in marginal marine environments. Mar. Geol. 3, 115-129 (1965). 

Helmke, E., and H. Weyland. 1991. Effect of temperature on extracellular enzymes occurring in permanently cold marine environments. Kieler Meeresforschungen Sonderheft 8 198-204. 

Mg-rich chlorites do not seem to form readily in low-temperature marine environments. Mixed-layer chlorite-vermiculites form fairly easily in magnesium-rich environments but complete development of the brucite sheets must be considerably more difficult. Mixed-layer chlorite-vermiculite is the predominant clay in the Lower Ordovidian limestones and dolomites of southern United States, usually over a thousand feet thick and extending over 500,000 square miles, yet very little chlorite is present (Weaver, 1961a). These mixed-layer clays and others like them appear to have formed on extensive tidal flats where the clays were exposed to alternating evaporitic... 

An alkaline marine environment high in H2S and HS" is favorable for incorporation of sulfur into organic matter HS" is an aggressive nucleophile. Such conditions also would have been favorable for the formation of polysulfides and elemental sulfur. All of these species, either alone or in combination, are expected to have played a role in the incorporation of sulfur into the vegetable debris that ultimately formed Rasa coal. Many of these species are known to be reactive with hydrocarbons at mild temperatures. Elemental sulfur reacts with hydrocarbons to form organosulfur compounds, including thiophenes at mild temperatures (28,29). Polysulfides react with conjugated ene carbonyls at room temperature to form thiophenes and other sulfur heterocycles (30). ... 

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