Using Oil Spill Dispersants on the Sea (1989) / Chapter Skim
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1 Use of Oil Dispersants: History and Issues
1 Use of Oil Dispersants: History and Issues
Pages 6-27
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From page 6... ...
These issues are discussed generally in this chapter and in more detail in later chapters. REASONS FOR TREATING OIL SPILLS Aesthetic and Ecological Damage Introduction of petroleum into the marine environment is a direct consequence of the production and transportation of crude of!
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From page 7... ...
The increased risk of a major of} spill was displayed dramatically when the first major tanker catastrophe the Torrey Canyon spin occurred. Public outcry from the Torrey Canyon spin and similar incidents stimulated development of a variety of response techniques to contain or remove spired oil before it could harm property or the environment.
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From page 8... ...
Contamination can close a commercial shellfish bed for years, resulting in a considerable financial loss to shellfish producers. In some regions of the world- such as Bermuda, several Caribbean islands, and the Middle East desalination plants provide an important source of drinking water for the surrounding sea.
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From page 9... ...
Indeed, a human health concern is that cleanup crews can receive doses of toxic fumes high enough to cause nausea and possibly other health effects. POTENTIAL SOURCES OF SPILLED OIL The worldwide input of petroleum to the marine environment was estimated by the National Research Council (1985)
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From page 10... ...
in the Gulf of Mexico in 1979 and 1980. Apart from oil discharges caused by military action in the Persia~n Gulf, the incidence of major tanker spills elsewhere has been dramatically reduced from 1974 to 1986 (Table 1-2~.
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From page 11... ...
Most spills are small and most spilled of! volume comes from only TABLE 1-2 Number of Oil Spills From Tankers Worldwide, 1974-1986 Barrels Year 50-5,000 >5,000 1974 92 26 1975 98 23 1976 67 25 1977 66 20 1978 57 24 1979 56 36 1980 50 13 1981 50 5 1982 45 1983 53 11 1984 25 7 1985 29 8 1986 23 7 SOURCE: International Tanker Owners Pollution Federation Ltd.
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From page 12... ...
. These spills are usually not treated with dispersants nor cleaned up by mechanical means.
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From page 13... ...
(67 percent of the total volume)
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From page 14... ...
Coast Guard, 1987. Mechanical Containment, Recovery, or Removal Mechanical means for oil spill mitigation include barriers (booms)
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From page 15... ...
HISTORY AND ISSUES TABLE 1-3 Cleanup Control Options and Their General Application Cleanup Operations and Options Application Water Under- Along- Shore Surface water shore line Containment and diversion Major options Booms Sorbent booms Surface-collecting agents Water jets Air jets Other possibilities Air barriers Gelling Viscoelastic additives Underwater containment Removal x x x x x x x x x x x Major options Skimmers x Sorption x x Sorbent booms x Biodegradation x x Other possibilities Burning x Sinking x Dispersants x x Cleanup of stranded oil Major options Flushing x Beach cleaning x Manual x x x Vegetation cropping x x Organism x rehabilitation Other possibilities Substrate removal x x Burial x Sandblasting x Steam cleaning x Natural Cleansing x x x 15 Full containment using a boom cannot be assured unless max~mum water speed at right angles to the boom is less than 1 kn. In faster currents, the barrier must be placed at an angle to the current to guide the floating oil toward slower current areas.
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From page 16... ...
Some of these devices have successfully recovered oil in seas higher than 4 ft. In large spills, the effectiveness the percent of surface oil removed by treatment has been low for mechanical cleanup systems; for example, possibly 10 percent during the Bloc Iblowout (Teal and Howarth, 1984~.
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From page 17... ...
Natural Removal Oil left alone is eventually removed from water surfaces and shorelines by a variety of natural means, including evaporation, photooxidation, solution, physical dispersion, sedimentation on particulate matter, and biological degradation. Although these natural processes may be slow, possibly as long as several years, they are generally conceded to be environmentally acceptable, and in some cases may be preferable to using active countermeasures.
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From page 18... ...
Rationale for Dispersant Use An initial reason for using dispersants is to respond to public and governmental concerns by preventing potential damage to birds, fish, marine mammals, and other natural resources; fouling of shorelines and boats; and contamination of drinking water sources. Dispersing an of!
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From page 19... ...
Logistics Application of dispersants can be accomplished more quickly than recovery of spired of} by mechanical means. Aerial spraying of chemical dispersants is usually the preferred method of application to use at sea, because it is more efficient and provides a wider range of coverage than application from boats.
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From page 20... ...
into the water column and lowering its concentration and the time of exposure of gametes, developing embryos, and larvae that dweD on or near the surface. Dispersant use may also limit the damage to sensitive nearshore nursery waters, especially if of} is effectively dispersed in areas remote (i.e., where natural processes can treat oil)
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From page 21... ...
of crude of} that spired from the tanker Torrey Canyon off the English coast in 1967. The extreme toxicity of these agents to marine life was attributed primarily to alky~pheno!
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From page 22... ...
Concerns about the environmental impact of dispersants stimulated considerable research in Canada, Europe, and the United States in the 1970s and 1980s. The Conference of the American Society for Testing and Materials (ASTM)
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From page 23... ...
Additional extensive experimental and developmental work on aerial spraying was done in Canada and the United States in the 1970s and 1980s (Cormack and Parker, 1979; Lindblom and Barker, 1978; Nichols and Parker, 1985; Ross et al., 1978~. Helicopter spraying systems were also developed in the late 1970s and were used to spray dispersants on the stick from the Rasbah 6 blowout along the coast of Saudi Arabia in 1980 (Martinelli, 1980; van Oudenhoven, 1983)
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From page 24... ...
Is the biological impact of dispersed oil greater or less than that of untreated oil? Using Chemical Dispersants to Remove Oil From the Surface of the Water Developing optimum techniques for applying dispersants under various conditions requires an understanding of the numerous factors affecting oil dispersion.
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From page 25... ...
The following are discussed in detail later in this report: the physical and chemical interaction of oil and dispersants to reduce interfacial tension (Chapter 2, "Composition of Dispersants") , slick structure, sea state, turbulent mixing of of} droplets in the subsurface water column (Chapter 2, "Fate of Oil Spilled on Open Water" and "Behavior of Oil-Dispersant Mixtures")
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From page 26... ...
Factors Affecting Toxicity of Chemical Dispersants and Dispersed Oil As discussed in later chapters, there is a wide diversity of use of chemical dispersants for the control of oil spills in various countries. A range of opinion exists concerning the biological effects resulting from the use or proposed use of chemical dispersants.
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From page 27... ...
· Is there need to further refine and standardize toxicity testing in laboratory studies? · Does chemical dispersion increase or decrease the amount of oil that attaches to solids in the water column and the amount of of!
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