Sea water contamination

Steam-turbine lubricants Lubricants in steam turbines are not exposed to such arduous conditions as those in engines. The main requirement is for high oxidation stability. However, they may be exposed to aqueous condensate or, in the case of marine installations, to sea water contamination, so they have to be able to separate from water easily and to form a rustpreventing film on ferrous surfaces, and it is usual to employ rust inhibitors. The problem of tin oxide formation on white-metal bearings is associated with the presence of electrically conducting water in lubricants and can be over-come by keeping the lubricant dry . 

The water content of system and heavy duty crankcase oils can generally be maintained below 0.2 and 0.5%, respectively. If water is detected, the first priority is to establish and correct the source of contamination. This is particularly true for sea water contamination because severe corrosion can occur very rapidly. 

Much of our discussion will centre on the diffnsion of chlorides into concrete as that is the major problem in most parts of the world either dne to marine salt spray or use of deicing salts. However, the cast in chlorides mnst not be overlooked especially when they are part of the problem. This often happens in marine conditions where sea water contaminates the original concrete mix and then diffnses into the hardened concrete. 

With the possible exception of systems using sea water, estuarial waters, and/or industrially contaminated waters for cooling, condi-... 

Water condition (sandy, oily, etc.) and t pe (river, canal, harbor, sea). The contaminating chemicals and/or minerals should be identified. Type of water treatment. 

Constancy of composition The validity of these arbitrary conversions depends on the constancy of the ratios of the various dissolved salts. It is a remarkable and important fact that, except where there is gross dilution or contamination, the relative proportions of the major constituents of sea water are practically constant all over the world. 

In sea-water systems such attack may occur under dead barnacles or shellfish, the decomposing organic matter assisting corrosion. Pitting is most likely to occur in polluted in-shore waters, particularly when hydrogen sulphide is present. In such contaminated waters non-protective sulphide scales are formed and these tend to stimulate attack. 

Tests by Clark for the Corrosion Sub-committee of the American Welding Society were carried out at severe marine and industrial sites. After four years, the greatest protection to steel was given by sprayed aluminium coatings combined with aluminium vinyl paint in the following environments id) sea air, ib) sea-water immersion, (c) alternate sea-water immersion and exposure to air (tidal conditions) and id) industrial atmospheres contaminated with sulphur compounds. 

These observations contrast with some of the results obtained in natural waters. In the experiments where contaminated sediments were equilibrated with Lake Michigan water for a number of days, the Pu(IV) that was on the sediments and was transferred to the water was oxidized to Pu(V), with the oxidation occurring either during or after desorption (15). The studies in the Irish Sea near Windscale show that although no more than 1 percent of the waste effluent stream is oxidized plutonium, approximately 5 percent of the plutonium released leaves the area in the currents of the Irish Sea as oxidized plutonium. Most of the plutonium, therefore, must be oxidized fairly rapidly in sea water. 

Desalination of sea water, or purification to eliminate dangerous ionic contaminants from industrial waste water involves important technological, scientific and financial risks. Most of them are related to the development of cheaper smart membranes that can mimic biological membranes. 

Leoni [366] observed that in the extraction preconcentration of organochlo-rine insecticides and PCB s from surface and coastal waters in the presence of other pollutants such as oil, surface active substances, etc., the results obtained with an absorption column of Tenax-Celite are equivalent to those obtained with the continuous liquid-liquid extraction technique. For non-saline waters that contain solids in suspension that absorb pesticides, it may be necessary to filter the water before extraction with Tenax and then to extract the suspended solids separately. Analyses of river and estuarine sea waters, filtered before extraction, showed the effectiveness of Tenax, and the extracts obtained for pesticide analysis prove to be much less contaminated by interfering substances than corresponding extracts obtained by the liquid-liquid technique. Leoni et al. [365] showed that for the extraction of organic micro pollutants such as pesticides and aromatic polycyclic hydrocarbons from waters, the recoveries of these substances from unpolluted waters (mineral and potable waters) when added at the level of 1 xg/l averaged 90%. 

Thus the application of the conceptual model to monitoring data shows an existence of the ecological risk of river waters entering in the Caspian Sea. This is connected with (a) loss or leaching of DDT and HCH residues with relatively low transformation from LPA, (b) possible secondary risk of water contamination by POCs desorbed from bottom sediments, and (c) POCs content in aquatic ecosystems at toxic concentrations for the most sensitive organisms. 

Picer et al. [49] described a method for measuring the radioactivity of labelled DDT contaminated sediments in relatively large volumes of water, using a liquid scintillation spectrometer. Various marine sediments, limestone and quartz in sea water were investigated. External standard ratios and counting efficiencies of the systems investigated were obtained, as was the relation of efficiency factor to external standard ratios for each system studied. 

Seafood may naturally contain small amounts of various PAHs, absorbed from the sea water. The aquatic environment is contaminated with PAHs due to oil spills, incomplete combustion of fossil fuels, industrial and urban effluents, extraction from creosoted wharfs and pilings, as well as from biosynthesis by plants and marine microorganisms. 

Contamination of system with process water, sea water, or condensate water... 

Titanium. Unlike other metals, titanium normally does not pit, is not susceptible to stress corrosion, is free from local corrosion under fouling organisms, is free from impingement and cavitation attack at velocities which attack copper-base alloys, and is not susceptible to sulfide attack in contaminated sea water. Experiments with water velocities at 20 to 50 feet per second show no attack on titanium. 

The use of sacrificial anodes for protection of the heads of the heat exchanger may not be so effective in brackish water. The water may be very corrosive because of pollution or contamination, even when the salinity is relatively low. More anodes, with closer spacing, normally are needed to give sufficient protection in brackish water than in sea water. 

Robertson, D. E. Role of Contamination in Trace Element Analysis of Sea Water. Anal. Chem. 40, 1067 (1968). 

PCB organic compounds found as soil and water contaminants continue to grow each year. They include polychlorinated biphenyls (PCBs), phenols, cyanides, plasticizers, solvents, and numerous industrial chemicals. PCBs were historically used as coolants in electrical transformers and are also known by-products of the plastic, lubricant, rubber, and paper industries. They are stable, lipophilic, and break down only slowly in tissues. Because of these properties they accumulate to high concentrations in fish and waterfowl in 1969 PCBs were responsible for the death of thousands of birds in the Irish Sea. 

Hydrolysis can explain the attenuation of contaminant plumes in aquifers where the ratio of rate constant to flow rate is sufficiently high. Thus 1,1,1-trichloroethane (TCA) has been observed to disappear from a mixed halocarbon plume over time, while trichlo-roethene and its biodegradation product 1,2-dichloroethene persist. The hydrolytic loss of organophosphate pesticides in sea water, as determined from both laboratory and field studies, suggests that these compounds will not be long-term contaminants despite runoff into streams and, eventually, the sea (Cotham and Bidleman, 1989). The oceans also can provide a major sink for atmospheric species ranging from carbon tetrachloride to methyl bromide. Loss of methyl bromide in the oceans by a combination of hydrolysis... 

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