[Advances in Marine Biology] Advances in Marine Biology Volume 8 Volume 8 || The Problem of Oil Pollution of the Sea

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<ul><li><p>M u . 7nur. Bid., Vol. 8, 1970, pi). 21.5 -306 </p><p>THE PROBLEM OF OIL POLLUTION OF THE SEA </p><p>A. NELSON-SMITH Department of Zoology, University College of Xwansea, </p><p>Swansea, Wales </p><p>I. Introduction . . .. .. .. .. .. * . 11. Sources and Control . . .. .. . . . . .. </p><p>A. Tanker Operation and General-cargo Shipping . . 3. Harbours and Marine Terminals . . . . . . C. Coastal Industry and Other Sources . . . . . . </p><p>111. Properties of Petroleum Oils .. .. .. .. A. Physico-chemical Characteristics . . .. .. B. I3ehaviour of Spilt Oil on Sea and Shore C. Detection and Identification . . . . ,. * . </p><p>IV. Effects of Oil Pollution . . . . .. . . .. A. Mode of Action and Toxicity of Oils . . .. .. B. Effects on Marine Comrnunities .. .. .. C. Carcinogenesis . . .. . . . . .. .. D. Rehabilitation of Oiled Birds . . . . .. .. E. Public Amenity and the Tourist Industry . . . . </p><p>V. Removal of Spilt Oil . . .. . . .. . . .. B. Dispersal, Sinking and Recovery at Sea . . .. C. Problems in Cleansing Shores . . .. . . .. </p><p>VI. Conclusions and Prospects . . .. . . .. .. </p><p>. . . . </p><p>A. Bacterial Degradation and Other Biological Processes </p><p>D. Mode of Action and Toxicity of Solvcnt-emulsifiers </p><p>VII. References .. .. .. . . . . . . </p><p>.. </p><p>. . </p><p>. . </p><p>.. </p><p>.. </p><p>.. </p><p>.. </p><p>. . </p><p>. . </p><p>. . </p><p>.. </p><p>.. </p><p>.. </p><p>. . </p><p>. . </p><p>.. . . .. .. . . . . .. </p><p>. . 215 </p><p>.. 219 . . 219 </p><p>. . 224 </p><p>.. 230 </p><p>.. 234 .. 234 </p><p>.. 236 </p><p>.. 240 </p><p>.. 243 </p><p>. . 243 </p><p>.. 258 </p><p>.. 262 </p><p>. . 263 </p><p>.. 264 </p><p>. . 266 .. 266 </p><p>.. 271 ,. 214 . . 280 .. 288 . . 290 </p><p>I . INTRODUCTION The Report from the Select Committee on Science and Technology </p><p>(1968) points out that oil pollution is referred to (as " slime ") in the Book of Genesis and by Herodotus. Such natural seepages still occur in petroleum-producing areas, but elsewhere, oil pollution of the sea results mainly from its transport or use as a fuel by shipping. Possibly the first account of this was by Jonas Hanway who in 1754 complained of leakages from wooden petroleum-barges in the Caspian Sea (Hawkes, 1961); a century later, these barges were still creating a pollution problem on the Volga. </p><p>The first widespread use for petroleum products was in lamps, where mineral oil began t o replace vegetable or whale oil in the mid- </p><p>215 </p></li><li><p>216 A. NELSON-SMITH </p><p>nineteenth century. It was shipped in barrels carried in the hold, like whale oil or any other liquid cargo, but even so was liable to spillage as with the schooner " Thomas W. Lawson )', wrecked on the Isles of Scilly in 1907 with the loss of her cargo of two million gallons of crude oil (Parslow, 1967a). Steamers did not at first engage in the petroleum trade for fear of fire, so the first true tankers were sailing vessels fitted out with wing tanks. The Anglo-American Oil Company's " Daylight )', one of the most successful, sailed on into 1921, although the steam- tankers " Gluckauf " and " Bakuin " entered the Batoum oil-service in 1886. At much the same time, the internal-combustion engine and the steam-turbine were invented. The Royal Navy turned t o oil-firing for the turbine-driven Tribal-class destroyers in 1908, while the first sea- going motor-ship '' Vulcanus )' was launched in 1910. </p><p>Much of the early pollution of European coasts was by fuel from the bilges and bunker-tanks of oil-fired or motor ships, whose numbers were increasing rapidly. Crude oil was mostly processed in petroleum- producing regions and tankers carried the refined products, many of which were clean light oils. The shipping lanes converging on the English Channel are the busiest in the world, so that the degree of pollution already became sufficient to prompt the passage in 1922 of the Oil in Navigable Waters Act, which prohibited the discharge of oil or oily water in British territorial waters. The United States followed with the Oil Pollution Act of 1924. In 1926 an international conference in Washington recommended the establishment of coastal zones 50-150 miles wide in which the discharge of oil should be prohibited ; agreement could not be reached, but the zones were recognized voluntarily by the shipowners' associations of many Western nations. The scheme formed the basis of a Convention drawn up by the League of Nations in 1935 but after the withdrawal of Germany, Italy and Japan from the League, this Convention could not be ratified and the outbreak of war in 1939 prevented further action. </p><p>I n 1938, world petroleum production was 278 million tons ; western Europe consumed 36 million tons of oil, of which the British share was 11 million tons. Rate of consumption was enormously accelerated by the 1939-45 war and subsequent industrial expansion, until by 1967 world production had reached 1 828 million tons and Britain alone consumed 85 millions tons (Select Committee, 1968 ; British Petroleum CO., 1968). During this period, the contribution made to world production by Middle East oilfields grew from nearly 4% to over 27% (Fig. 1). By 1960, the growth of the European market and the political instability of the Middle East and other oil-producing regions made it economically and politically prudent to build refineries at the point of </p></li><li><p>217 </p><p>FIG. 1. Main oil shipments to western Europe-A, from 1963 to early 1967 ; R, in late 1967. The width of tho arrows is proportional to the tonnage carried. Compare with similar maps by the Ministry of Transport (1953) and IMCO (1964); after British Petroleum Review-( 1967). </p></li><li><p>218 A . NELSON-YMITII </p><p>consumption. Thus not only was there a great increase in the sea- transport of oil ; there was a basic change in its nature. Large tankers entering European waters now carry crude oil, while refined products (whose spillage creates less of a pollution problem) are carried overland or in small coastal tankers. </p><p>Recent governmental efforts to control oil pollution of the sea have been reviewed in a US. State Deyt. Report (1959) and by Barclay- Smith (1958, 1967). Various meetings of naturalists and wildfowlers in 1952 were followed by the appointment of the Faulkner Committee, which reported the next year (Ministry of Transport, 1953). I n 1954 an international conference in London drew up a Convention which, like that of 1935, prohibited the discharge of oil within specified coastal zones. The United Kingdom was the first to ratify the Convention, passing the Oil in Navigable Waters Act of 1955; by 1958, having been ratified by ten nations, the Convention came into force. I ts admini- stration passed to the Intergovernmental Maritime Consultative Organization (IMCO) when that body was formed by the United Nations in 1959. The United States ratified the Convention in 1961, after a further international conference in Copenhagen. </p><p>Amendments to the 1958 Convention extending the prohibited zones (to include, for example, the entire Baltic and North Seas) and regulating further classes of vessel were proposed at an IMCO conference in 1962 and eventually came into force in 1967 (IMCO, 1962, 1967) ; but by this time " Torrey Canyon " had been stranded off the coast of Cornwall, bringing to a head the apprehension felt in many quarters about the operation of increasingly large tankers. Proposals discussed at subsequent IMCO meetings include regulations governing the con- struction, navigation and routeing of tankers as well as measures directly concerned with pollution prevention and control (Goad, 1968). Legal problems arising from the " Torrey Canyon " incident, sum- marized by Marshall (1967; see also Edwards, 1968) were discussed at, an International Legal Conference on Marine Pollution Damage con- vened by IMCO in Brussels during November 1969. Procedures were laid down by which a coastal nation might act if a casualty on the high seas threatened to cause severe pollution. A Convention was drafted placing strict liability for compensation upon the owners of an oil- carrying ship from which the cargo escapes or is discharged. As an interim arrangement, nearly 60% of the world tanker fleet had already subscribed to the TOVALOP plan, which from October 1969 provided for much of the cost of cleaning up an oil spill to be covered by the owners, encouraging them to take quick action in minimizing the resultant damage. </p></li><li><p>THE PROBLEM O F OIL POLLUTION O F THE SEA 219 </p><p>11. SOURCES AND CONTROL A. Tanker operation and general-cargo shipping </p><p>The largest and most dramatic spillages of oil a t sea have resulted from the collision or stranding of tankers. It has been argued that the current trend towards very large bulk carriers should reduce this risk, because fewer voyages are necessary to keep any one refinery or tank- farm supplied. Nevertheless, in the three years ending with April 1967, 91 tankers went aground and 238 were involved in collision. 19% of the groundings and 9% of the collisions resulted in cargo spillage-a total of 39 incidents. I n the first five months of 1968, a further 39 tankers were involved in various accidents, not all resulting in oil-spills (Brockis, 1967; Select Committee, 1968). When a large tanker is damaged, it is obvious that she is potentially capable of losing a great deal of oil ; modern design trends do little to minimize this possibility. Before the 1939-45 war, typical tankers carried 10 000-12 500 tons of cargo at speeds up to 12 knots. To meet wartime demands, American shipyards went into mass-production of the T2 tanker, carrying some 16 500 tons at a sustained speed of 144 knots. For some years after the war, this type formed the backbone of tanker fleets before it was ousted by " supertankers " (as they were called in the early 1950s) of about 24 000 tons. </p><p>Tankers are constructed on a basic plan of three longitudinal series of tanks ; in the T2 and related designs, these were about 36 ft long. After the closure of the Suez Canal in 1956, even larger and faster tankers became economically desirable ; the implications of their deviation from earlier designs are reviewed in the Batelle-Northwest Report (1967). To reduce hull weight and simplify the plumbing, alternate wing-tank divisions became swash bulkheads (incomplete divisions which merely reduce cargo movement) ; in later designs this practice was extended to the centre tanks. Many recently-built vessels of 40 000-60 000 tons have tanks which are effectively 80-100 ft long. A greater capacity (and larger tanks) can be incorporated in older tankers by the process of " jumboizing ", in which a new and larger centre-section is inserted between the original bows and stern, which contain expensive machinery, crew-quarters, etc. Many T2 tankers were enlarged in this way, although the best-known example is now ( ( Torrey Canyon ", which " grew " from 67 000 to 118 000 tons. The capacity of today's '( supertankers "in the 100 000-500 000 tons range is obtained by increasing draught and breadth rather than length, so that a tank only three times as long as those in the T2 design may con- tain fifty times as much oil-the entire cargo of a pre-war tanker. Some </p></li><li><p>220 A. NELSON-SMITH </p><p>dry-cargo bulk carriers of over 100 000 tons, designed for alternative oil-carrying service, lack even the longitudinal bulkheads. Doubt has been cast on the seaworthiness of some such designs if more than one compartment should be damaged. I n these circumstances, the simplifi- cation of pumping arrangements reduces flexibility in the control of cargo, while the development of better anti-corrosion treatments permits the use of thinner plating, which is less resistant to violent impacts. </p><p>Although they are capable of high speeds, all but the very largest of modern tankers still have a single screw for reasons of economy. Their manceuvrability in narrow waterways is necessarily restricted. For example, Torrey Canyon was making about 16 knots when she struck Pollard Rock and would otherwise have required at least 2 miles to come to a dead stop; other supertankers require as much as 7 miles (Wiebe, following Edwards, 1968). The turning circle of such tankers ranges from one-half to over 2 miles. Of course, modern navigation aids should compensate for this (see Kluss, 196813). Although she lacked a Decca Navigator, Torrey Canyons radar had a range of 40 miles. Had she been following a prescribed course, as all civil aircraft are required to do, she would have avoided disaster. Traffic separation is already observed, on a voluntary basis, in the Strait of Dover and other regions of high traffic density; its operation is dis- cussed by Dilling (1968). However, the 40 000-ton tanker Anne Mildred Brravig was rammed by a small coaster in fog off the Elbe estuary in 1966 when proceeding on a faultless course. The collision was entirely the responsibility of the coaster, yet such small craft would not be subject to the proposed controls (see Brockis, 1967). Further preventive and remedial measures are discussed in a U.S. Congress Committee Report (1967). </p><p>Measures which can be taken to control pollution after accidental damage has occurred depend, of course, on the severity of the accident. A tanker still having her own power may be able to move off towards repair facilities or the open sea and might well have surplus tank capacity into which she could pump oil from the damaged compart- ment. Even when a stranded vessel is stuck fast, it is rarely necessary to jettison oil overboard in order to avoid immediate disaster. Unfortu- nately, the value of the ship is invariably much greater than that of the cargo and current salvage contracts provide no reward for the avoidance of pollution. The possibilities of pumping the cargo into an empty tanker standing off the wreck were well demonstrated when the Esso Margarita successfully received over 15 000 tons of the 18 000 tons of fuel-oil carried by the General Colocotronis , which ran onto a </p></li><li><p>THE PROBLEM O F OIL POLLUTION O F THE SEA 221 </p><p>reef in the Bahamas in March 1968 (Spooner and Spooner, 1968; Fig. 2). However, it is often impossible for vessels of suficient capacity to approach as close as this ; transfer of cargo becomes unacceptably slow, especially if the stricken tanker has lost the use of her pumps. Holds- worth (1968) and Kluss (1968b) discuss the equipment and methods </p><p>FIG. 2. Esso Margarita (foreground; 1 1 000 dwt) unloading fuel-oil from the * General Colocotronis (18 000 dwt), stranded on a reef off Eleuthera (Bahamas). Three-quarters of her cargo was safely removed, after which she was hauled off and sunk in deep water (photo : Frederic Maura). </p><p>available for salvaging the cargo in these circumstances, but weather conditions may, in any case, make such lightening impossible. Alter- natives listed by Holdsworth include gelling, freezing and burning. Gelling is now feasible ; the material of choice is slow setting and thus does not require mixing. The process is expensive, but may be cheaper than clearing up the spill. Freezing would require a vast amount of energy and might lead to the brittle fracture of an already weakened </p></li><li><p>222...</p></li></ul>