at the time of loading. Any oil found on beaches would then be analyzed, and the ship of origin identified. ties: Such tracer chemicals would have to have the following proper b. They must be identifiable in concentrations like 107, C. d. that only a few pounds are required for each tanker load, yet they must not occur naturally in any kind of oil, except in much lower concentrations. They must not be soluble in sea water. There must be enough combinations available to mark each of the roughly 4000 tankers now in use. This requires at least 12 different tracer chemicals. One suggestion for such a tracer scheme is described in Appendix A. An alternative method which has been proposed is to not bother to identify the source of any pollution which occurs, and to pay for the cleaning costs through an insurance scheme to which all ships are required to contribute, thus spreading the costs over the whole oil transportation industry (Ref. 8). The contributions would be calculated as a function of how much oil a particular ship carried, and its route. This would encourage a self-policing attitude by the ship operators, in order to reduce the insurance costs. 5. Shore Facilities A necessary adjunct to any system requiring tankers to bring the residue of cleaning operations or dirty ballast into port will be facilities for disposal on shore. In some cases, if a refinery is present, the residue can be processed and the oil recovered. Otherwise there must be some sort of dump available. At present, only a limited number of crude oil loading ports have such facilities, and the volumes which can be handled are small. The ship would therefore be required to retain the waste material on board until it arrived at a refinery or a port with disposal facilities where it could be discharged. This would probably mean some increase in operating expense. B. POLLUTION FROM OTHER SOURCES Possible defenses against the other sources of oil pollution have mostly already been mentioned in connection with tankers. For pollution from natural seepage, continuous deposition of bacteria might help. For pollution from accidents, the discussion under Sections A-2c and A-2d is applicable. The pollution from sunken tankers is probably not very important, but it is perhaps possible to locate the tankers and pump out the oil. This may even be economically rewarding, and it would at least be a test of the Navy's developing underwater technology. The sunken tankers of interest are all on the continental shelf, and hence not in deep water. The location problem should therefore be relatively easy, particularly since the rough location already exists in Navy records from World War II. In Section II it was noted that the amount of pollution from ballasting fuel tanks with sea water in ordinary ships is almost comparable to that from tankers. The long-term cure here is probably to design ships with separate fuel and ballast tanks. For the short term, it may be useful to attempt to separate the oil remaining in the fuel tanks from the sea water ballast prior to discharge of the ballast. If this could be done, the water could be discharged (up to a point where some given acceptable amount of oil is present) and the oil retained in the fuel tanks, to be mixed with the new oil which is to be loaded for fuel. Unfortunately, the most obvious method of separation, namely gravity, is difficult because fuel oils now in use have a specific gravity of 0.998 (Ref. 1). But perhaps some other separation technique could be invented. Aside from this, it is unlikely that much can be done about ordinary ships. Prohibiting the discharge of oily ballast water at sea or in harbors is possible only if facilities exist to dispose of it on shore, or under controlled conditions. But the number of nontankers operating all around the world and the number of ports in use are so large that such facilities in useful numbers would be quite expensive to construct. C. DATA REQUIREMENTS Finally, as remarked in the Introduction, a world-wide study to provide some reliable numbers on both the source and amount of oil pollution would be highly desirable. What is needed is, among other things: 1. 2. An estimate of how much oil/year comes ashore on the entire An estimate of how long the oil has survived in the sea 3. A survey of natural seeps, both as to location and flow 4. 5. rates. A survey of offshore drilling to see whether there really is pollution from this source. A survey of tanker operations to see how many tankers do in fact dump polluted ballast into the sea. ACKNOWLEDGMENT The study activities of Robert Gomer and S.C. Wright were very helpful in the preparation of this paper. Valuable comments were contributed by Freeman Dyson, Henry Kendall, Bernd Matthias, and Allen Peterson, along with Boyd Ladd and Edward Wenk, Jr., of the National Council on Marine Resources and Engineering Development. REFERENCES 1. J.E. Moss, "Oil Pollution in the Sea," American Petroleum 2. 3. 4. 5. 6. 7. 8. Institute, 1963. This report is by far the most detailed and complete survey of the pollution problem that we came across. S.E. Morison, "History of United States Naval Operations in World War II," Volume I. New York Times, June 11, 1967. Also Reference 1. World Almanac, 1967. E.C. Holmes, "Offshore Activities of the Petroleum Industry," J.V. Dennis, "Oil Pollution Survey of the U.S. Atlantic Coast," "A Proposal for Limiting Oil Contamination from Tankships," Oberheim Associates, June 5, 1967. 15 |