This paper describes equipment and techniques for responding to oil spills. Various techniques for the containment, cleanup and recovery of oil spills are examined; advantages and disadvantages of each are considered. Along with providing insight for oil spill response, this paper discusses environmental factors which can contribute to the success or failure of a cleanup operation.

" Oil is the life blood of our modern industrial society. It fuels the machines and lubricates the wheels of the world’s production. But when that vital resource is out of control, it can destroy marine life and devastate the environment and economy of an entire region…. The plain facts are that the technology of oil-- its extraction, its transport, its refinery and use-- has outpaced laws to control that technology and prevent oil from polluting the environment…" (Max, 1969). Oil in its many forms has become one of the necessities of modern industrial life. Under control, and serving its intended purpose, oil is efficient, versatile, and productive. On the other hand, when oil becomes out of control, it can be one of the most devastating substances in the environment. When spilled in water, it spreads for miles around leaving a black memory behind (Stanley, 1969).

Oil spills, no matter large or small, have long been of concern to pollution control authorities in this country. Due to its destructive nature, once an area has been contaminated by oil, the whole character of the environment is changed. When it has encountered something solid to cling to, whether it be a beach, a rock, the feathers of a duck or gull, or a bather’s hair, it does not readily let go (Stanley, 1969). By its nature oil on water is a seeker. Consequently, oil slicks on water seem to have an attraction for water birds. Once a bird settles on the oil mass its feathers become soaked with oil. This result in death by drowning through loss of buoyancy, ingestion of oil, loss of body heat, and inability to fly-- which would result in starvation or make them targets for predators. When surface feeding fish swim into the floating oil, their bodies and gills become coated with oil, which in most cases would result into death. If death does not result from such contact, their bodies absorb the taste and odor of the oil, which would make them unfit for human consumption for a long time. As the oil moves towards the land it could bring death to marine life that inhabit the shallow, near shore areas (Stanley, 1969).

The possible effects of pollution upon our recreational areas must also be considered. The usefulness of beaches for recreation suddenly ends. Snow-white cruisers and sailboats will show a dark smear at the waterline; small children after playing on the beach come home with oily feet; swimmers are coated with oil patches which cling to their skin and their hair (Stanley, 1969). In addition to aesthetic and ecological concerns, one must also consider the economical concerns. Coastal regions can suffer economically from damage done by oil spills to recreation areas, harbors and vessels, and commercial shellfish grounds. During summer months, beaches along the coasts of most maritime countries are crowded with people on weekend outings and vacations. Thus, there is considerable economic incentive in coastal recreation areas to protect beaches from spills or to clean them up quickly (National Research Council, 1989).

Many factors- local currents, weather, water temperatures and the composition of the oil itself, among others – affect the degree of long-term environmental damage from big oil spills (Maclean, 1993). Crude oil shipped in tankers varies from light oils similar to gasoline, to heavy compounds that resemble asphalt. Lighter elements evaporate quickly while heavier ones spread out on waves and ocean currents and sink. Heavy oil is more likely to be deposited in shorelines and can be extremely difficult to clean up if it washes onto soft, absorbent sand (Maclean, 1993). Moreover, heavy oils are largely insoluble, forming coherent masses, which float on the surface or become stranded on the shore, and can thus cause damage at a considerable distance from their point of release (Nelson, 1971). The heavy oil that eventually sinks can cover bottom-dwelling species, such as crabs, with a thick film and damage feeding and breeding species

There are countless opportunities for oil to get out of control. Many are due to mechanical failure of the equipment, or due to human carelessness and mistake. There are risks implicated in the materials involved and the means of transporting the oil. The risks involve terminals, loading docks, refineries, tankers, freighters, pipelines, tank cars, trucks, filling stations, just to name a few (Stanley, 1969). In addition, sea pollution may result from the production, refining, and distribution patterns, which have been, developed to meet ever-increasing fuel demands. Since the world’s main petroleum producing areas do not coincide with the areas of greatest consumption, the transportation of petroleum has increased with consumption. In addition, the changing pattern of refining location has significantly increased the proportion of crude products moved over greater distances. This change has resulted in an increased chance of sea pollution by persistent oil. This increasing movement and storage of products has also increased the risk of inland water contamination (Jaggar, 1971).

Pollution of the environment by oil can occur almost anywhere at any time. Some recent examples are 1) Gulf War—January 1991 at the Kuwaiti and Saudi Arabian coast. 240 million gallons of light Arabian crude was spilled, 2) Huntington Beach, California February 1990 more than 9,500 barrels of crude oil spilled into marine waters , 3) Exxon Valdez—March 24, 1989 Prince William Sound, Alaska. 10.8 million gallons of Alaskan heavy crude oil was spilled. Exxon spent over $6.2 billion cleaning up the spill, but scientists say that nature might have done a better job on its own. There are still some deposits of oil under rocks, and 4) Amoco Cadiz—March 17,1978 the English Channel. 68.7 million gallons of light Arabian crude oil was spilled. The spill contaminated beaches, polluted the fishery and killed the wildlife in marshes along France’s Brittany coast. The local fishery has returned to pre-spilled levels, but there are still globes of oil-soaked sand on the beaches (Maclean, 1993).

Cleaning up an oil-contaminated area is time-consuming, difficult, and very costly. The term costly does not only refer to the amount of money needed for the clean up, but it also refers to the destruction of fish and other wildlife, damage to property, contamination of public water supplies, and many other losses. These losses may extend for months or years (Stanley, 1969). In addition to the above concerns, the increased size of oil tankers, density of waterborne traffic, and offshore petroleum production operations strongly recommends advance planning for prevention and control of oil spillage accidents, and for the development of defensive measures in the event accidents do occur (Swift et al.,1969). It must be emphasized that a key element in any effort aimed at limiting the consequences of a major oil spillage incident will be the ability to rapidly respond with preventive measures. Therefore, contingency planning and the establishment of an advisory system become extremely crucial (Swift et al., 1969).

It is important to look at the current state of technology of containment and control of major oil spillage on water, and the various techniques for the recovery of the oil. Each technique should be examined and its advantages and disadvantaged must be considered. In addition, environmental factors, which can contribute to the success or failure of a cleanup operation, must also be examined.

Discussion:

Containment, Cleanup, and Recovery of Oil Spills:

There are three major options for responding to oil spills: mechanical containment and collection; use of chemical dispersants; and natural removal (no cleanup action). Countermeasures that are less widely used or have major limitations are burning, sinking, absorption and enhanced biodegradation. In determining the best possible countermeasure for a given situation, availability and applicability must be compared to potential environmental damage (National Research Council, 1989).

Mechanical Recovery:

Mechanical recovery is the transfer of oil from the water surface to some transportable form of temporary storage by the help of booms to contain or divert oil, skimmers or sorbents to recover or remove it from the water surface, hoses, and pumps (Institute of Petroleum, 1975). Performance of any of these equipment, however, can be severely limited by oceanic conditions and weather, including currents, waves, and wind, and by the nature of the oil slick (National Research Council, 1989).

Although spilled oil may emanate from a small localized source, it can rapidly spread to cover large area of water. How thick the resulting slick would be depends on the amount of time the oil spends on the surface, the type of oil spilled, and its viscosity at the ambient temperature. A principal factor in removing oil expeditiously and effectively by mechanical means is the thickness of the oil spill. The rate of oil recovery by any mechanical device decreases with decreasing oil thickness. Thus rapid response with coordinated use of oil-containment booms, skimmers, transfer pumps, temporary storage and auxiliary craft all deployed and operated by a skilled team of men is what is required for the recovery to be successful.

For effective oil recovery, equipment must be employed at appropriate locations. Typical locations were recovery equipment is used are 1) exposed waters of the open sea, 2) the more sheltered waters of narrows and estuaries and of harbor entrances, 3) rivers, and 4) enclosed waters of harbors and lakes. In order for mechanical recovery to be successful, all its components must be employed effectively by a team of skilled men. The team of workers must be trained in how booms and skimmers work, and to know where and under what circumstances they operate the best.

Figure 1. Typical Oil Recovery Operation (Institute of Petroleum, 1975)

BOOMS:

A boom is a floating barrier used to contain oil, they are mechanical barriers, which extend above and below the water surface. They are used to: 1) divert oil spills to areas where cleanup can be performed, 2) contain and concentrate spilled oil, and 3) protect environmentally sensitive areas threatened by oil spills (Robert et al., 1989). Although the size, shape, and materials of construction vary, booms generally have four basic components. As shown in figure 2 most booms include 1) a means of flotation, such as a air-filled compartment or solid float, 2) a freeboard section which extends above the water surface and prevents oil from flowing over the top of the boom, 3) a skirt which extends below the surface to keep oil from escaping beneath the boom, and 4) a tension member which gives the boom strength to withstand forces exerted by currents, waves, and winds.

Figure 2. Conventional Boom Components (Robert, J.M. and Associates, 1989)

In addition, for maximum result, booms must have the appropriate physical characteristics. Flexibility is the ability to follow the water surface. If flexibility is low, it is possible for the oil to be lost beneath the boom when its drought is reduced by waves. If the freeboard is inadequate oil and water may splash. Booms cope better with a long swell than with a short shop as they follow the water surface more satisfactorily with the former (Institute of Petroleum, 1975). In addition, booms must be strong enough to withstand operational stresses and a certain amount of rough handling and they must have sufficient draught to avoid loss of oil beneath the submerged portion. The fabric of the boom must be resistant to oil and sunlight. It should also be of the form that is readily cleansed. The fabric should not take too many storage places on board a ship or stored in land, and it must be rapidly deployed (Institute of Petroleum, 1975).

Booms are grouped into four categories: offshore, harbor, calm water, and fire containment. Offshore booms are used to contain oil in the open sea and are designed to withstand 9-12 ft. waves. Harbor booms are used at offshore drilling sites, terminals, and other near-shore facilities. Calm water booms are small, lightweight, and designed for oil spill containment in shallow near-shore water. Fire containment booms are used in calm water conditions to ensure that a thick layer of oil is maintained for burning (Robert et al., 1989).

Environmental conditions effect boom operation. Booms must operate satisfactorily under the prevailing wind and wave conditions, but the problems associated with deploying it safely and expeditiously under adverse conditions must be taken into account. Most booms cannot provide effective oil spill containment in currents above 1 knot. Current velocity of 0.3 m/s normal to a boom can be considered as the upper limit for the retention of oil. These currents will cause oil to escape under the boom’s skirt. In areas where the water current is above 1 knots, booms can be used to divert oil to areas where the current is lower and containment can be achieved. Wind is another factor which affects boom performance. Unless the boom is securely anchored form both sides, strong winds may cause it to move back and forth. This results in splashing of the oil over the boom (Robert et al., 1989).

Besides the environmental factors, one must take into consideration the possible locations for boom layout. Complex arrangements for laying out booms are not easy under emergency conditions, therefore certain amount of contingency preparation is desirable. The sites chosen should not be where critical velocity for the collection of oil is likely to be exceeded. For example narrowest sections of a river have the highest velocity, even though less boom is used. Wider sections with good access to the bank and having beds of good holding quality for anchors are most desirable. Booms that are not anchored or operated in the free-floating mode might be attached to a boat at each end to maneuver the boom in order to contain and concentrate the oil.

Because oil spills occur in inconvenient locations and that awkward journeys are involved in getting equipment to the site, booms, mooring and other gear should be no heavier or bulkier than necessary. For spills on inland waters or reservoirs, light booms weighing less than 1.5 kg/m must be used. For a spill at the sea or on estuaries heavier booms weighing more than 7 kg/m are employed. Considerable length of boom maybe needed to contain an oil spill thus most booms are made in unit lengths, which can be coupled together prior to or during deployment.

Rapid assembly and development of booms is essential, but recovery is a less urgent matter. Most booms are best recovered after towing to sheltered waters or to a harbor. One way is to beach them at high tide and then deflate them and/or dismantle them when tide recedes. Another way is to use a roller system which maybe a preferred method for recovering inflatable booms especially at sea. After recovery, booms must be cleaned of oil, simple booms are cleaned easier than ones with complicated sections.

One way of cleaning booms is by housing down and scrubbing them with emulsifiers. Another method is to use solvents. Storage of booms merits careful consideration because most booms are likely to spend most of their life in storage. Compactness in storage is associated with gas or air-filled booms, which can be deflated when not in use. Booms of fabric construction that are kept in cool storage and protected from direct sunlight can be expected to have a storage life about 10 years. Regular inspection is desirable, and the booms should be inflated at intervals to check for air leaks or damage in storage (Institute of Petroleum, 1975).

Barriers prevent the oil to become less thin, but also pack the oil into a thick layer with minimum amount of water. However there are disadvantages to booms that is they are cumbersome to assemble, deploy or repair. Maintenance effort may be considerable if weather conditions are not quite calm, and cost is considerable (Institute of Petroleum, 1975).

Skimmers:

At the heart of any mechanical oil spill recovery system is some device for removing the layer of oil form the water surface refer to figure 3. For optimal results the device no matter of what type must remain in the oil water interface and continue to operate there. Skimmers are used for the recovery of the oil (Institute of Petroleum, 1975). Skimmers must be brought very quickly to the scene of the incident to deal with the oil before it has spread out into a thin layer. Since it is virtually impossible to predict with any degree of certainty where an incident will take place, this implies that: 1) the equipment must be either air transportable, 2) it must be sufficiently cheap that a large number can be available at each of the most vulnerable places so that in the event of an incident, the nearest equipment would have a relatively small distance to move from its base, or 3) it must be a large equipment designed for high speed sea operation which must be at all times ready to set out (Institute of Petroleum, 1975).

Generally skimmers are transported to the scene of oil spillage. However, the majority of skimmers do not call for special transport arrangements. On land, those that are small in size and are easy to manhandle can readily be carried and transported by road on conventional vehicles, usually together with other items such as cable, hoses, couplings, pumps, and etc. For larger skimmers, specialist vehicles are needed. On the sea, small skimmers are easily carried below deck on a suitable vessel, as the size increases they are more treated as deck cargo (Institute of Petroleum, 1975).

All skimmers work most efficiently on a relatively thick and continuous layer of oil but, as they operate, they necessarily deplete this layer in their immediate vicinity. Therefore, either oil must be kept coming to the skimmer or the skimmer must be moved into an undepleted area. The first method relies on the water current and the arrangement of the booms, the later suggests maneuvering of the skimmer. Skimmers built into self-powered crafts are the most maneuverable, and to a large extent independent of other vessels for power supplies and temporary storage for recovered oil. Other skimmers must rely on a mother vessel for power supplies and storage of recovered oil. Power supply cables, oil delivery hoses and mooring lines between such skimmer and the mother ship have to cross the boom and may be deployed either under or over it. This method is liable to deform the boom and allow oil to escape (Institute of Petroleum, 1975).

Skimmers are grouped by removal capacity. Large skimmers remove oil at a rate more than 200 T/hr, medium skimmers remove oil at a rate of 50 T/hr and the small skimmers remove less than 10 T/hr 3. If the equipment has a self-contained reservoir for the collected oil, the capacity of this container may limit the removal rate unless it can readily and quickly be emptied into temporary storage or into a vehicle or ship to take it away (Institute of Petroleum, 1975).

Environmental factors must also be considered when dealing with skimmers. For instance, wave height effects the operability of skimmers. Equipment intended for use in calm waters is small. For sheltered waters and on the open sea it must include devices, which will deal with oil at a reasonable rate. Moreover, majority of skimmers suffer form interference from trash, seaweed and most devices have some means incorporated for preventing this. Trash is most damaging where it can enter pipes, valves, and pumps. Trash can also build up at the water surface near the unit and prevent oil from being pulled towards the skimmer and thus give a low oil recovery rate (Institute of Petroleum, 1975). Skimmers can be cleaned relatively easily using dispersants, but these materials interfere with the pick-up capability of skimmers that rely upon adhesion to metal or other surfaces, and should therefore not be used if the skimmer is to be deployed at the same incident (Institute of Petroleum, 1975).

 Figure 3. Typical Skimmer Device (Robert, M.J. and Associates, 1989)

 
Temporary Storage:

Few skimmers are large enough to contain all the oil recovered and there is therefore a need to transfer oil to a larger container for removal and disposal away from the site of the recovery operation (Institute of Petroleum, 1975). Oil containment and recovery is an urgent operation which should not be held up while problems associated with the ultimate disposal of the recovered oil are solved. Even where the disposal means has been agreed it is very seldom possible to transfer recovered oil there directly or continuously. Some form of temporary storage is required, usually a buffer between continuous skimming and intermittent removal to disposal (Institute of Petroleum, 1975).

In selecting suitable temporary storage equipment, the most important factor is the location of oil recovery operation. If recovery is being operated essentially from a beach or riverbank, temporary storage is likely to be land-based with ultimate removal probably by road refer to figure 4. A variety of containers placed on the ground have been used as temporary storage for recovered oil and water. Two such tankers are skid-mounted road tankers or collapsible tanks. In other circumstances, storage and removal will be water-borne and will involve the use of tankage in or on a vessel. For temporary storage at the sea the containers used have to be robust enough to withstand sea conditions. For water based recovery operations, coastal tankers or large self-propelled tank-barges are recommended (Institute of Petroleum, 1975).

For reliable storage, temporary storage must be tough and resistant to puncturing by rocks or other obstacles. If the storage is freestanding, it must be strong enough to contain the weight of the recovered oil. On the other hand, if it is on the deck of a vessel, the added weight of the recovered oil must not imperil the stability of the vessel (Institute of Petroleum, 1975).

In considering the problems involved in dealing with oil spills, there is a natural tendency to concentrate attention on the major items of equipment and to overlook the other equipment that seemingly plays only a support role. For example items such as a portable generator and lights for use at night, fencing to keep away livestock and sightseers, various length of rope, and clean-up rags. The mechanical recovery of oil would not be possible in the absence of such supporting items.

 Figure 4. Shoreline Temporary Oil Storage (Robert, M.J. and Associated, 1989)

Chemical Dispersant:

Most oils spilled on water rapidly spread into a slick, with thickness form several millimeters down to one micrometer depending on the oil type and the area available for spreading. Wind-driven waves and other turbulence can break up the slick, producing more or less spherical droplets ranging in size from a few micrometers to a few millimeters. Sometimes, these droplets can be stabilized by natural surface-acting agents (surfactants) present in the oil or contributed by the sea-surface microlayer. These surfactants stabilize the droplets by orienting in the oil-water interface with the hydrophobic part of the surfactant molecule in the oil phase and the hydrophilic part in the water phase, thereby diminishing the interfacial tension (National Research Council, 1989). Chemicals of various types are available for this purpose and have been known by a variety of names, including dispersants, detergents, solvent/emulsifiers, emulsifying agents, etc. (Jaggar, 1971). Applying chemical dispersants to an oil slick greatly increases the amount of surfactant available and can reduce oil-water interfacial tension to very low values. The interface stabilized by the surfactant, permits droplets to survive despite frequent collision with adjacent droplets (Peter, 1995).

The key components of a chemical dispersant are one or more surface-active agents, or surfactants—sometimes called "detergents." They contain molecules with both water-compatible (hydrophilic) and oil-compatible (hydrophobic) portions, the mechanism of chemical dispersion is shown in figure 5. Most chemical dispertants also contain a solvent to reduce viscosity and facilitate dispersal (National Research Council, 1989).

 Figure 5. Mechanism of Chemical Dispersion (National Research Council, 1989)

An initial reason for using dispesants is to respond to public and governmental concerns by preventing potential damage to the birds, fish, marine mammals, and other natural resources; fouling of shorelines, and contamination of drinking water sources. Dipersing an oil spill will make is less visible, and may reduce its economic an ecological impact—provided the water volume, which it disperses into, is great enough. If the oil is dispersed into small volume of water with poor circulation, the ecological impact may in fact be increased (National Research Council, 1989). Dispersants may be especially valuable when other countermeasures fail, for example an open-sea spill is moving onshore, but waves are too high to permit the use of booms and skimmers, the use of dispersants is the best choice. Another example is if tidal currents are so strong that oil would be carried under a boom, resurface, and threaten a sensitive area chemical dispersants are used instead.

Application of dispersants can be accomplished more rapidly than recovery of spilled oil by mechanical means. Aerial spraying of chemical dispersants is usually the preferred method of application to use at sea, since it is more efficient and allows for a wider range of coverage than application from boats. However, prior to application of dispersants, its impact on the habitats being sprayed upon must be examined. Although, marine ecosystems, such as salt marshes, mangroves, and coral reefs, and bird nesting areas are extremely sensitive to damage by oil, the use of dispersants raises questions about the relative environmental effects dispersed oil. Thus dispersants may be applied when it is judged that the impact of dispersed oil on organisms, habitats, and ecological processes will be less than that of oil alone. Accurate exposure assessment for surface and subsurface oil is critical to estimating the hazards of dispersed oils to seabirds, whose protection is a major reason for dispersant use over open water (National Research Council, 1989). Two situations which may warrant dispersant use are: 1) a large spill in the bowhead whale migration corridor during late August and early September and 2) oil slicks threatening a shoreline containing a large bird population (Robert et al., 1989). However, dispersants when effectively used will aid in the recovery of oil, and also enhance the rate of biodegradation of oil by nature (National Research Council, 1989).

Shoreline Cleanup & Natural Cleanup:

If oil strands on a shoreline, attempts are usually made to remove it using mechanical means, by flushing, by manual pickup, or by physically removing the substrate. In most cases, shoreline cleanup is expensive and may be environmentally damaging. However, the only method for cleaning and restoring public beaches and accessible shorelines near fisheries and industrial areas is removal of oil (National Research Council, 1989). Natural removal is another method for dealing with spilled oil. Oil left alone is eventually removed form water surfaces and shorelines by different natural means, including evaporation, photooxidation, physical dispersion, sedimentation, and biological degradation. These processes may take several years, but are considered acceptable for remote areas (National Research Council, 1989).

Burning:

Burning is defined as the process of burning an oil spill on land or water. In order for oil on water to burn, the slick must be relatively fresh and at least 3 mm thick. Since volatile components in the oil begin to evaporate as soon as the spill occurs, the potential for burning decreases with time. Depending on wind speed and temperature, as much as 50% of an oil slick can evaporate in 24 hours or less. Once this occurs, it may be impossible to ignite the oil remaining on the water surface. In addition, burning at the sea surface is not generally effective due to the rapid transfer of heat to the water (Swift et al., 1969). However, where spilled oil cannot flow well, as in the Arctic and on ice, there has been effective use of burning as a cleanup technique (National Research Council, 1989).

Fresh oil slicks, which have sufficient thickness, can be ignited by matched, burning rags, air deployable igniters, and lasers. Burning produces a tarry residue, which could be difficult to clean up. Under optimum burn conditions, about 10% of the oil will remain on the water as burn residue. Burning also creates black smoke, which could violate air quality control regulations and present a health hazard for nearby communities (Robert et al., 1989).

Burning may not be prudent near populated areas, because it produces a variety of toxic chemicals which may adversely affect human health and welfare. For example, soot and polynuclear aromatic hydrocarbons created by burning can cause cancer and mutations in living tissue. Along with these items, the smoke may also contain zinc, vanadium, lead, nickel, or other metals which were in the oil. It is important to recognize that the combustion products from burning can travel great distances before falling to earth. In view of the environmental risk associated with burning, this response technique should not be used for large spills without permits form federal, state and local agencies responsible for air quality control (Robert et al., 1989).

Sinking:

The addition of chalk or treated sand has been used or proposed as a means of sinking oil. However, sinking is seldom completely effective initially, and some oil tends to resurface. Moreover, oil that sinks to the bottom contaminates benthic life and degrades more slowly than when floating, dispersed, or dissolved in water (National Research Council, 1989). A large number of powdered and granulated materials of high density are available which, if distributed over the oil, will absorb it and sink it. There are difficulties, of course, in applying light powdery materials in open-sea, such as windy conditions. A more serious drawback is that many sinking materials do not render the oil permanently immobile and release of the oil, causing re-pollution after some time, can normally be expected (Jaggar, 1971).

Absorption:

There are numerous compounds and materials available to collect oil slicks. Four types of collecting agents have been identified as having been either demonstrated or suggested for oil slick recovery. These are: 1) floating absorbents such as straw and sawdust, 2) plastic or other polymeric materials such as polyurethane foam, 3) gelling agents, and 4) demulsifiers. Most of the floating absorbents are inexpensive and can be readily disposed of by either burning or burial. However, recovery of oil values form these absorbents are not easily accomplished. The use of plastic or other polymeric materials offers and excellent solution to the problem, since no residues are left on the ocean bottom and large quantities of oil can be reclaimed for subsequent use (Swift et al., 1969).

Absorption is applied as an aid to the manual removal of small spillage of light fluid oils, which are otherwise difficult to deal with. They have to be applied liberally and as they do not have strong oil retention properties, and care must be taken in the disposal of the oil-soaked agglomerte, preferably by scooping it into containers (Nelson, 1971).

Enhanced biodegradation:

Constituents of oil degrade naturally when attacked by bacteria, algae, protozoa, and marine fungi. Enhancement of biological degradation has been proposed using specially chosen bioengineered microbes. However, microbes that degrade hydrocarbons are readily available everywhere in nature, except in polar waters where the rates of breakdown are very slow and variable. It does not appear necessary in most cases to enhance their action (National Research Council, 1989).

Conclusion:

To be effective, an oil spill recovery operation must be seen as a whole. Form the time that a spill is reported until the operation is completed, all the various activities must be fully coordinated. For this, a skilled and well-practiced team is invaluable. Such a team knows its terrain, knows where equipment of all kinds is stored or is available, knows whom to contact for further information or material, and knows what to do without delay. It is evidently not possible to define beforehand all the circumstances of an expected spillage. However, it is possible to identify in general terms the problems of deployment and operation which will arise despite the individuality of spills that specify the details in each case. Since an oil spill usually spreads quickly and in doing so rapidly escalates the scale of the recovery problems, speed of action is crucial. An accurate assessment of the situation is required as soon as possible. This should always include an aerial reconnaissance for all but the most local spills and is preferably carried out by trained observers in a helicopter. Knowledge is required of the source of the oil, estimates of the amount that has already leaked and of the possible maximum amount of oil at risk, and a summary of the present position of the slick. An assessment is also needed of relevant factors such as currents and tides, state of the sea, the weather forecast, depths of water, possible obstacles, and so on- clearly an appraisal that can only be made through experience and local knowledge. Mechanical containment and recovery provide the appropriate cleanup method, but the choice of which equipment to use is a crucial factor in the cleanup process. A team needs to know what equipment is at its disposal, and what are the limits of the equipment’s utility (Institute of Petroleum, 1975).

A sound administrative structure is also essential to ensure that teams are properly established, that their responsibilities and lines of communication are clear, and that adequate pre-planning and practice is undertaken. Pre-planning includes such activities as defining suitable sites for placing and mooring booms, evaluating equipment and the associated manpower requirements. Oil spills cannot be stopped, but one can hope that through adequate preparation, oil spills and be effectively contained and recovered thus minimizing its effect on the environment.
 

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Max, N.E. 1969. Oil pollution and the law. Washington, D.C.: The Bureau of National Affairs, Inc.

National Research Council. 1989. Using oil pollution dispersants on the sea. Washington, D.C.: National Academy Press.

Nelson, A.N. 1971. Effects of oil on marine plants and animals. London: Institute of Petroleum.

Peter Lane. 1995. The use of chemicals in oil spill response. MI: Ann Arbor.

Robert, J.M. and Associates. 1989. Oil spill response guide. New Jersey: NOYES DATA Corporation.

Stanley, E.D. 1969. Oil pollution: Problems and policies. Washington, D.C.: The Bureau of National Affairs, Inc.

Swift, W.H, . C.J. Touhill, W.L. Templeton, and D.P. Roseman. 1969. Oil spillage prevention, control, and restoration—state of the art and research needs. Washington, D.C.: The Bureau of National Affairs, Inc.

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