Air pollution near harbors and inland seas is going to be an urgent problem for marine plants.
In this paper, some elemental experiments for exhaust emission controls of marine diesel engines are discussed, such as;
1. Techniques of NO_x measurements in the case of high water concentration.
2. Exhaust emission characteristics affected by injection timing, exhaust valve timing, and inlet air temperature.
3. Effects of fuel-water emulsion introduced into the combustion chamber.

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In recent years, industrial waste matters and wastes which are discharged from daily life have become enormous in quantity and disposed volume of these wastes to the seas are abruptly increasing. As the result, the demolition of natural environment has been expanding to the seas.
In such condition, the counterplot should be considered as a world-wide, important problem.
Under the fact that control of waste discharging of the ships to the seas has been intensified ever more, it is necessary to have a sewage treatment plant on board which conform to the rule requirement.
In the paper, information on treatment plants concerning sewage are dealt with, that is, Type, Characteristic, Construction, etc. (i.e. holding tank, discharge type, non-discharge type) and also requirements from various regulatory agencies such as Japanese Government, IMCO and U.S.C.G.

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The fundamental tests are made on adhesion of oil to study the properties of rotating disc type oil remover and quantity of remained oil on the tank wall of oil tanker.
In the tests of rotating disc the data are taken for the quantity of oil adhered in a moment to the disc plate under the many conditions. On the other hand the remained oil at after enough time is measured on the surface of steel plate having every size and poses, especially the effect of volatility is considered in crude oil.
In both tests it is found out that the quantity of oil adhered to the disc is affected by the viscosity of the oil itself.

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Light refined oil products, such as naphtha, gasoline, kerosene and gas oil have been included among the objects of the “International Convention for Prevention of Pollution from Ships, 1973” by IMCO. However, there have been few studies on the dispersion and weathering processes of these oils.
The purpose of the paper are an experimental estimation of evaporation rates and solubilities of the light oils in closed separatory funnels and an open water tank, and a quantitative analysis of optical characteristics of thin oil films on water surface.
The higher values of evaporation rate from oil slicks are obtained in order of naphtha, gasoline, kerosene, crude oil (Iranian light) and gas oil on the same conditions of air velocity, air temperature and water temperature.
It is indicated from gas chromatography analysis that the aqueous fractions mainly consist of light parafin and light aromatic hydrocarbons. In the open water tank system, the contents of dissolved fractions into water phase are estimated to be almost the same order for gasoline, kerosene and crude oil, and have a tendency of increasing as a decrease of the air velocity.
From the study on reflectivity and the result of observing the colour of oil film under daylight, it is shown that the“silvery sheen”state corresponds to the first occurrence of an optical interference in the colour range of blue violet.

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The purpose of this study is to develop a devices which is possible to be carried promptly to the scene of oil spillage, by a tugboat usually available in the port area, and withdraw spilled oil at sea. The study was made during 3 years from 1973 to 1975.
In this oil-spill removal devices, an oil guide fence picks up and gathers spilled oil, a suction float and a pump to absorb it, and a rough oil-water separator and remove oil from the oil-water mixture.
The features of the suction float are that it is an oil-proof, all-weather rubber float which is inflated by low pressure air, and a light aluminum suction box hanging down, which moves in the same motion as the float. The extremely good synchronization of the float and suction box was confirmed by the experiment of suction capability, conducted at sea.
It also has a stabilizer wing which is given floating power by pulling, and keeps the depth of suction nozzle always at a regular level, against changes of recovering speed. And its effectiveness was also confirmed by the experiment.
A centrifugal separating system was adopted as thr rough oil-water separator.

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In 1972, one year prior to the 1973 Intergovernmental Maritime Consultative Organization (IMCO) Convention, a special committee made up of representatives from the Ministry of Transportation, Japan Ship's Machinery Development Association, shipbuilders, and oil/water separator manufacturers launched a three-year research/development program to devise an improved load-on-top (LOT) system. The system, designed to automatically monitor, record, and control the rate and amount of oil discharge at sea, was completed in 1975 following exhaustive tests at Nagasaki Technical Institute of Mitsubishi Heavy Industries, and installed in the “ALRIYADH, ” a 237, 000 tdw Mitsubishi-built Japanese tanker. The system for this particular ship application was designed with two 100 t/ h-capacity oil/water separators, two kinds of oil content meters, monitoring instrument, etc., and in 1976 put to full-scale shipboard tests four times during the ship's ballasted voyages between Japan and Middle East. The shipboard test showed that the improved load-on-top system could completely satisfy the oil discharge standards adopted by the 1973 IMCO Convention and, at the same time, provided valuable clues to the further refinement of the system. With its basic design for tanker application now completed, the improved load-on-top system can readily be installed in tankers.

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When tanks are washed with waterjets of tank cleaning machines, an electrically charged mist is generated by Lenard Effect, and it spreads uniformly throughout the tank. Mean charge density in tanks produced by washing with clean seawater is about 10^-8 C/m³.
However, the charge in the mist might be increased considerably by the use of the very high capacity fixed machine, recirculated wash water (contains oil), hot wash water (above 60°C), chemicals.
The calculated value of the maximum space potential in large tank is about 40 kV. This potential exceeds the hazardous value 25 kV.
A discharge from an unearthed object to earth is suspected as a possible source of incendive spark in tank. Example of possible unearthed conductor is a slug of water produced by the washing process.
The test of possibility of creating water slug shows that the very high capacity fixed washing machine is able to produce dangerous water slugs, on the other hand, with the portable type of washing machine no such water slugs can be detected.

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The disposition of petroleum was managed to sulphuric ash used of sulphuric acid and to watery solution, Zinc, Lead and Copper contents contained in it were analysed by the apparatus of Anodic Stripping Voltammetry (ASV) used of mercury electrode.
The number of analytical sample was crude oil 44 samples, Heavy oil 9 samples and marine weathering oil 15 samples.
We conclude from the analysis of them described above that: -
(1) in crude oils, content of Zinc include 0-16 ppm, Lead is 0-5 ppm, Copper is 0-3 ppm, but we could not recognize the result being characterized by the place of origin.
(2) in heavy oils, there is not little relation between the property to metal contents.
(3) in marine weathering oils, metal contents have a tendency to be enriched respectively.
However, we conclude that analysis of metal contents in petroleum is exceedingly available, with the object of discrimination about identity of oil samples.

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