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It might seem incongruous that a research focused organisation such as the International Union for Pure and Applied Chemistry would pay attention to an issue as pragmatic as oil spills. After all, an oil spill tends to be viewed as a very practical matter, its issues characterised by loss of a valuable commercial product, damage to the environment, high costs of clean up, high legal liabilities, and very much media attention. Oil spills are not generally considered a pure or even applied chemistry issue. However, this would be a very short-sighted interpretation. Effectively every element of an oil spill, whether environmental, physical, operational or legal, is related to the complex chemistry of the oil and its breakdown products released to the environment. Indeed, it would be safe to say that if petroleum were a simple chemical product, the difficulties inherent in clean up of an oil spill would be much reduced, no matter what the origin or cause of the spill. The chemical nature of oil is directly related to the fate and environmental impacts of spilled oil, whether on water or on land, and to the effectiveness of the diversity of countermeasures which might be deployed. While evaluation of the effects of spilled oil on the environment receives much attention in forums with a biological or toxicological focus, which often do take into consideration chemical factors, the complex topic of the chemistry of oil spills in direct relation to countermeasures is examined more rarely. The various chapter in this document discuss a diversity of oil spill countermeasures, and target the chemical and consequently physical behaviour of oil which determines its characteristics at the time of the spill. While oil spills occur in fresh and salt waters, and on land, marine oil spills remain the larger issue - there tends to be more oil spilled, environmental problems are more complex, and countermeasures are more difficult to implement. The following papers generally reflect and review the current state of knowledge in their topic area, and are representative of the most recent surge in research and development activities, stimulated particularly by the Exxon Valdez spill in Prince William Sound, Alaska in 1989. It appears that oil spill research undergoes cycles of interest, activity and funding, linked to key oil spills. Previously, the Torrey Canyon spill in the English Channel off Land's End, in the United Kingdom in 1967 provided general incentive for research and development, as did the Amoco Cadiz spill off the coast of Brittany, France in 1978. Other oil spills, such as the 1968 Santa Barbara Channel, California spill, or the Braer spill off the Shetlands in 1993, among others, have also stimulated specific areas of research and development on the basis of issues that arose in their particular spill scenario. The articles in this publication have been contributed by recognised international experts in the spill response field, and have received the benefit of peer review. The articles are representative of the major categories of oil spill response research, spanning a wide range of technologies, supportive knowledge and experience, to include reviews of: This collection of review articles concludes with an evaluation of oil spill response technologies for developing nations, appropriately so since that is where much of the oil development and production currently occurs in the world. One area which has seen much recent expansion is that of the essential linkage between detailed understanding of spilled oil physical/chemical properties and the effectiveness of response countermeasures. Crude oils and oil products are known to differ greatly in physical and chemical properties and these tend to change significantly over the time course of spilled oil recovery operations. Such changes have long been recognised to have a major influence on the effectiveness of response methods and equipment, which increases the time and cost of operations and risk of resource damage. All countermeasures are influenced, whether sorbents, booms, skimmers, dispersants, burning of oil and so forth. The incentive is for a rapid and accurate method of predicting changes in oil properties following spill notification, which could be used in both the planning and early phases of spill response, including an initial specific selection of an effective early countermeasure. In later stages of the response, more accurate planning for clean up method and equipment deployment would shorten response time and reduce costs. An additional benefit would be more effective planning for recall of equipment not needed, as well as potentially decreasing the risk of natural resource damage and costs due to more effective spilled oil recovery. The concept of "Windows of Opportunity" for oil spill response measures has been derived from multiple investigations in industry and government research organisations. Although dispersants have been used to date in almost one hundred large spills world-wide, government approval for dispersant use has long been inhibited by a lack of understanding of the factors determining the operational effectiveness of dispersants, and the environmental trade-offs which might need to be made to protect sensitive areas from spilled oil. Recent advances in chemical dispersant development, formulation of low toxicity dispersants with broader application, and better understanding of dispersant fate and effects have combined to a more ready acceptance of this countermeasure by many, although not yet all, regulatory authorities throughout the world. In addition to the category of dispersants, chemical countermeasures include many diverse agents, such as beach cleaners, demulsifiers, elasticity modifiers and bird cleaning agents, each with a unique and specialised role in clean up activities. However, the concerns for the use of these 'alternative chemicals' relate to the interpretation and application of toxico-ecological data to the decision process. If in the future the ecological issues concerning chemical treating agents can be further successfully resolved, the oil spill response community will have an increased range of options for response. However, extensive laboratory and field testing is required in many instances for new chemical dispersant materials and demulsifiers to improve the effectiveness of these materials on weathered oils and water in oil emulsions. The acceptance of in situ (i.e. 'on site') burning of spilled oil has been limited by valid operational concerns about the integrity of fireproof booms, the limited weather window for burning due to the rapid emulsification of oils, the need to develop methods for the ignition of emulsified and weathered oils, and public concerns about the toxicity of the smoke generated during burning. However, burning provides an option, another tool in the tool-box, for the responder called in to combat an oil spill. Burning decreases the amount of oil that must be collected mechanically, thus reducing cleanup costs, storage, transportation, and oily waste disposal requirements. It also would decrease potential contact with sensitive marine and coastal environments and consequently reduce the potential for associated damage costs. Laboratory and field studies over the last ten years have addressed essential information requirements for feasibility, techniques, and effectiveness, as well as health and safety. The results of research in situ burning has led to its acceptance in a number coastal jurisdictions throughout the world, prompting the response industry to purchase and position in situ burning equipment and train its operators to use this alternative technology in approved regions. Although not a direct recovery measure in itself, the application of remote sensing to oil spill response assists in slick identification, tracking, and prediction, which in many instances is an early requirement for effective response. An inadequate ability to see spilled oil seriously reduces effectiveness of oil spill response operations. Conversely, good capability to detect spilled oil, especially areas of thick oil, at night and other conditions of reduced visibility could more than double response effectiveness and greatly enhance control of the spill to minimise damage, especially to sensitive shorelines. Advances have been made in both airborne and satellite remote sensing. It has become possible to move from large and expensive to operate airborne systems to small aircraft, more widely available and practical for spill response operators. Also, the limitations in delayed data processing and information communication are being overcome by development of systems operating in functional real-time, which is essential for enhanced response capacity. Spill detection using satellites has also advanced markedly since 1989, with the ongoing intention to provide coverage of oil spill areas as early warning, or when flying by aircraft is not possible. An early useful application was an ERS-1 satellite program for detection of oil slicks, launched in 1992. More recently, spill detection capability has been developed for the Canadian Radarsat satellites, ERS-2 and a few other satellite programs. The topic of bioremediation of spilled oil, that is, to use microbes to assist in clean up, is a corollary to the deployment of traditional countermeasures. It had not seen much operational or regulatory support until the Exxon Valdez spill, where it was initiated as a spill mitigation method, establishing bioremediation as a major oil spill R&D area. Bioremediation of oil spills was defined as being one of three different approaches: enhancement of local existing microbial fauna by the addition of nutrients to stimulate their growth; 'seeding' the oil impacted environment with microbes occurring naturally in that environment; and, inoculating the oil impacted environment with microbes not normally found there, including genetically engineered bacterial populations. Research emphasis and regulatory countenance has been predominantly on the first approach. Evaluation of operational utility of is continuing to identify conditions under which bioremediation can be used in an environmentally sound and effective manner, and to make recommendations to responders for the implementation of this technology. The issue of hydrocarbon toxicity has been examined in petroleum refinery and petrochemical workers for more than a decade, and experimentally in test animals for a much longer period. However, there has been little specific information available on the effects of oil spills on human health, neither for oil spill response workers nor for incidentally exposed individuals. More recently, as reviewed in an article on human health effects in this publication, some reports have been published of skin irritation and dermatitis from exposure of skin to oil during cleanup, as well as nausea from inhalation of volatile fractions. Although there are to date no epidemiological studies of exposure by oil spill workers to petroleum hydrocarbons, the matter is drawing increasing attention. One of the more important issues surrounding the choice and extent of application of oil spill countermeasures is knowledge about the ecological effectiveness of such response, that is, the balance point between continuation of clean up activities and letting the environment take care of its own eventual recovery. It is the last point which has driven much of the discussions and research associated with the concept of 'how clean is clean', or, how much cleanup is enough or too much. The results of such diverse research efforts are being used increasingly and successfully to link spilled oil chemistry to countermeasures practices and equipment. The advances are being integrated into more effective response management models and response command systems. In summary, applied chemical research and development has actively contributed to an enhancement in oil spill response capability. Nonetheless, it seems that the pace of oil spill research and countermeasures development is slowing. The decrease is at least temporally associated with a decline in the frequency and magnitude of oil spills in recent years. Spill statistics gathered by organisations such as the publishers of the Oil Spill Intelligence Report, show that world-wide oil spill incidence and volume have continued to decline since the time of the Exxon Valdez spill event (see the Oil Spill Intelligence Report publication " International Oil Spill Statistics: 1997 ", Cutter Information Corp.). It is probably not coincidental that the amount of funding available for oil spill research and development, from both government and private industry sources, has declined similarly. In that context, the following articles are more a statement of currently accepted knowledge and practice, rather than being a 'snapshot in time' of intense ongoing research activities. The articles serve to capture the applied chemistry knowledge and experience of practitioners in a complex field, application of which remains essential for the development of improved oil spill countermeasures, and their effective use in real spill situations.

This paper presents an integrated scientific and engineering strategy to improve and bring planning and decision-making for marine oil spill response to a higher level of knowledge. The most efficient, environmentally preferred, and cost effective spill response is dependent on the following factors: chemistry of the spilled product, quantity, location, response time, environmental conditions, and effectiveness of available response technologies at various degrees of oil weathering. Time windows is a highly targeted process, in which the selection of response technologies will be more efficient, cost effective, technically correct, and environmentally sensitive and appropriate. The strategy integrates dynamic oil weathering data and performance effectiveness data for oil spill response technologies derived from laboratory, mesoscale, and experimental field studies. Performance data has been developed from a wide range of viscosities of different weathering stages of transported oils into a dynamic oil weathering database to identify and estimate time periods, called "technology windows-of-opportunity." In these windows, specific response methods, technologies, equipment, or products are more effective during clean-up operations for specific oils. The data bases represent the state of the art for response technologies and research in oil spill response. The strategy provides a standard foundation for rapid and cost effective oil spill response decision-making, and is intended for use by local, state, federal agencies, response planners, clean up organizations (responders), insurance companies, tanker owners, and transporters. It provides policy, planners and decision-makers with a scientifically based and documented "tool" in oil spill response that has not been available before.

Introduction: A "Boom" is a floating mechanical barrier used to control the movement of substances that float according to ASTM F-818 Standard Terminology Relating to Spill Response Barriers. (ASTM, 1994). Since oil has been transported by sea, accidental spills have occurred from time to time, but only since the 1960's has its spillage along coastlines or within harbor areas caused enough public concern to demand that it be removed immediately. Large disasters, such as the grounding of the " Torrey Canyon " and the Santa Barbara drilling platform blowout, put pressure on the oil producing community to prevent spillage and to develop procedures and equipment to recover the spills that did occur. Experimental booms were introduced in the early 1960's but it wasn't until later in the decade that their manufacture became commercially viable. Relatively crude booms to contain or control the spread of spilled oil were developed and some were assembled on site. Logs were tied together with old conveyor belting nailed between the ends; oil drums were strapped to plywood sheets connected with rubber or fabric; canvas was sewn over fishing floats knotted along a line. Although these booms were relatively effective in calm water when a small volume of oil was spilled, most of them were cumbersome to maneuver and they quickly failed when waves or current were present. Spills in the early 1970's, along with growing environmental awareness, prompted legislators, both national and local, to require that the responsible parties clean up their act. Worldwide entrepreneurial spirit spawned several dozen small manufacturing enterprises to meet local and, in some cases, international demand for cheap efficient booms. In the mid 70's, several events happened which shaped the spill response industry and started the evolution leading to the better products and response techniques which we use today. The Arab Oil Embargo of 1973 raised the price of a barrel of oil to the point that the cost of the product lost in a spill became relevant. U.S. governmental agencies, including E.P.A., M.M.S., and Coast Guard developed regulations that fined the spillers of even small amounts of oil. Money was spent by government and the oil industry on research and test facilities to understand the limits and differences of boom designs, resulting in improved performance. Oil terminals in most major harbor areas pooled their resources and formed local and regional oil spill response cooperatives (Etkin, 1991). The U.S. Navy, being a large buyer of booms, contacted the American Society of Testing and Materials (ASTM) to see if they had any people working on the subject of spill response products in general and specifically on standardization of boom connectors. They did not, so they issued an invitation to the industry at-large to form a committee to write standards on that subject. Committee F-20 was born. It took ten years to publish F-962 Standard Specification for Oil Spill Response Boom Connector , but along the way, over 40 consensus Standards (ASTM, 1994) have been published to aid users and manufacturers alike in the selection of spill response products and guidelines for their use. This chapter will discuss the types of booms available today, the problems associated with their use under various environmental conditions, special products for unusual situations, and also thoughts regarding future developments.

Introduction: The purpose of any oil spill response is to minimise the damage that could be caused by the spill. Dispersants are one of the limited number of practical responses that are available to respond to oil spills at sea. When oil is spilled at sea, a small proportion will be naturally dispersed by the mixing action caused by waves. This process can be slow and proceed to only a limited extent for most situations. Dispersants are used to accelerate the removal of oil from the surface of the sea by greatly enhancing the rate of natural dispersion of oil and thus prevent it from coming ashore. Dispersed oil will also be more rapidly biodegraded by naturally occurring microorganisms. The rationale for dispersant use is that dispersed oil is likely to have less overall environmental impact than oil that persists on the surface of the sea, drifts and eventually contaminates the shoreline. The development of modern dispersants began after the Torrey Canyon oil spill in 1967. Many lessons have been learned since that spill, and consequently the modern dispersants and application techniques in use today have become an effective way of responding to an oil spill. For example, the dispersant response to the Sea Empress spill in 1996 demonstrated that dispersants can be very effective and prevent a much greater amount of environmental damage from being caused (6). This chapter describes the chemistry and physics of dispersants, planning and decision-making considerations, and finally their practical application and operational use in oil spill response.

Introduction: The use of in situ burning as a spill response technique is not new, having been researched and used for a variety of oil spills since the late 1960s. In general, the technique has proved effective for oil spills in ice conditions and has been used successfully to remove oil spills in ice-covered waters resulting from storage tank and ship accidents in Alaska, Canada and Scandinavia. Although there have been numerous incidents of vessel oil spills that inadvertently caught fire, the intentional ignition of oil slicks on open water has only been seriously considered since the development of fire-resistant oil containment boom beginning in the early 1980s. The development of these booms offered the possibility of conducting controlled burns in open water conditions. In situ burning operations using these booms have been conducted at three spills in the last decade: a major offshore tanker spill, a burning blowout in an inshore environment, and a pipeline spill into a river. In situ burning of thick, fresh slicks can be initiated very quickly by igniting the oil with devices as simple as an oil-soaked sorbent pad. In situ burning can remove oil from the water surface very efficiently and at very high rates. Removal efficiencies for thick slicks can easily exceed 90%. Removal rates of 2000 m3/hr can be achieved with a fire area of only about 10,000 m2 or a circle of about 100 m in diameter. The use of towed fire containment boom to capture, thicken and isolate a portion of a spill, followed by ignition, is far less complex than the operations involved in mechanical recovery, transfer, storage, treatment and disposal. If the small quantities of residue from an efficient burn require collection, the viscous, taffy-like material can be collected and stored for further treatment and disposal. There is a limited window of opportunity for using in situ burning with the presently available technology. This window is defined by the time it takes the oil slick to emulsify; once water contents of stable emulsions exceed about 25%, most slicks are unignitable. Research is ongoing to overcome this limitation. Despite the strong incentives for considering in situ burning as a primary countermeasure method, there remains some resistance to the approach. There are two major concerns: first, the fear of causing secondary fires that threaten human life, property and natural resources; and, second, the potential environmental and human-health effects of the by-products of burning, primarily the smoke. The objective of this chapter is to review the science, technology, operational capabilities and limitations and ecological consequences of in situ burning as a countermeasure for oil spills on water. The main focus of this section is on marine oil spills in open water conditions. The use of in situ burning for spills in ice conditions is dealt with in another chapter. Much of the content of this chapter is updated from an in-depth review of in situ burning produced for the Marine Spill Response Corporation (MSRC) in 1994 (ref. 1). Interested readers are encouraged to refer to the original report for fully-referenced details of the summary presented here. The MSRC report is available from the American Petroleum Institute in Washington, DC.

Mechanical countermeasures for oil spill response have various effectiveness and operational limitations under certain spill situations. This has led to an interest in and use of alternative treatment methods. This chapter reviews the potential utility of one such group, non-dispersant chemical countermeasures, in controlling the adverse impacts from marine oil spills. The types of non-dispersant chemical countermeasures presented here include: herding agents, emulsion treating agents, solidifiers, elasticity modifiers, and shoreline cleaning agents. Each countermeasure group is discussed separately to provide a definition, mechanism of action, and effectiveness and environmental considerations for the group. Where ever possible, examples are given of countermeasure use during an actual spill. In addition to the groups mentioned above, a few other treating agents are briefly described under the section "Miscellaneous Agents" to illustrate other, less prominent types of chemical countermeasures. Non-dispersant chemical countermeasures appear to have discrete response niches , i.e., situations where the countermeasures are well-suited and offer potential benefits. The key is matching conditions for optimal effectiveness with the appropriate incident-specific characteristics and window of opportunity. The practical aspects of logistics are not addressed because, if their potential utility can be demonstrated, the resolution of these issues would follow.

The interaction of micron-sized mineral particles with stranded oil reduces its adhesion to solid surfaces, such as sediments or bedrock. The net result is the formation of stable, micron-sized, oil droplets that disperse into the water column. In turn, the increase in surface area makes the oil more available for biodegradation. Oil and Fine-particle Interaction ("OFI") can explain how oiled shorelines are cleaned naturally in the absence of wave action in very sheltered coastal environments. Fine-particle interaction can be accelerated during a spill response by relocating the oiled sediments into the surf zone. This has been achieved successfully on two occasions to date: the Tampa Bay response in Florida, and the Sea Empress operation in Wales. Sediment relocation also causes physical abrasion by the hydraulic action of waves so that the processes of fine-particle interaction and surf washing usually occur in combination on open coasts.

The separation of water from oil that is collected in any oil spill recovery operation is a continuing and necessary requirement during every stage of the effort. Its importance is reflected in the cost of transport and storage of large volumes of oily water, the salvage value of separated oil and the added labor costs associated with long-term recovery operations. This paper addresses the effects of weathering and emulsion generation which increase the problems normally associated with water extraction. Separation theory, practical separation technology and recommendations for the future direction of research and development are presented.

Introduction: Remote sensing is useful in several modes of oil spill control, including large area surveillance, site specific monitoring and tactical assistance in emergencies. Remote sensing is able to provide essential information to enhance strategic and tactical decision-making, potentially reducing incidence of spills by providing a deterrent factor, decreasing response costs by facilitating rapid oil recovery and ultimately minimising impact. Marine oil spills can be separated into two categories of relevance to the type of remote sensing technology which might be used to detect and respond to the incident. A first category is non-accidental discharges, which can include incidental losses from vessels due to hull or equipment leaks, as well as oil discharged intentionally during deballasting and tank-cleaning activities. While these non-accidental discharges tend to be small in themselves, they are frequent and contribute much more to the overall introduction of oil to the marine environment than accidental spills, and are of increasing international regulatory concern. Accidental spills are much less frequent, but typically involves much larger releases of oil. Such oil spills are high profile events for which rapid and effective emergency response is needed to contain and recover the spilled oil. In many countries, an appropriate and effective response capability is required by law, such as demanded by the Oil Pollution Act of 1990 in the US, as well as by recent amendments to the Canada Shipping Act in Canada. There is a growing recognition that using remote sensing, especially airborne, to aid cleanup response efforts can mitigate the effects of oil on the environment, as well as reduce cleanup costs. Airborne remote sensing sensing in the support of spill response operations has a mixed level of interest by spill responders when viewed globally. In the US, for instance, airborne remote has had varying degrees of success in meeting operational expectations, and thus is not yet fully integrated into national, regional and area response plans and operations. By comparison, the record of successful use in the UK, for instance, is such that remote sensing support is contracted by the UK Coast Guard on a stand-by basis and used routinely when a significant spill occurs. As another example, airborne remote sensing technologies are now being adopted by the Australian Maritime Safety Authority to support its spill response actions. Low altitude aircraft have proven to be the most effective tactical method for obtaining information about spills and assisting in spill response. Combined with accurate oil drift computer model forecasting, these two methods were the primary strategic tools used for environmental response planning during the IXTOC-1 and Arabian Gulf spills, although less useful for guiding tactical operations (Pavia and Payton, 1983; Cekirge et al., 1992). Conversely, essential tactical support was provided by aerial remote sensing for the application of dispersants, a major spill response in the Sea Empress spill in Southwest Wales (Harris, 1997; Lunel et al., 1997). Currently, the use of imaging satellites for spill response is restricted because of limited spatial resolution, slow revisit times and often long delays in receipt of processed image data. The topic of oil spill monitoring by imaging satellites has been reviewed by Bern (1993a,b). There are significant advances being made, however, to increase resolution and coverage, as well as in the speed of image product delivery. Sensing oil on water by satellites appears best suited for routine surveillance purposes. There are synergisms in protecting the environment and property from oil spills which can be achieved by an integrated approach which draws on the remote sensing advantages of airborne and satellite imaging technology. There are many potential users of such remote sensing information, in government and private sector organisations. Government authorities use such information in surveillance, for example in the North and Baltic Seas, detecting spills when they occur and for identification of the spiller, which could be a vessel discharging illegally. Many government organisations also maintain an organised oil spill response capability, which would be supported by remote sensing information in oil spill response operations. The private sector includes the primary oil industry operating globally, and oil transporters, which carry responsibility and potential liability in the event of a spill. Other potential users are oil spill response organisations which might offer a sub-contracted remote sensing capability to their clients. Other private sector groups include the insurers for the shipping industry, who are directly and immediately interested in keeping both the costs of the response and oil spill impact damage as low as possible. The news media is a additional potential user, interested in quality graphical representation of the oil spill, as is true for any disaster event.

Introduction: This chapter addresses chemical aspects of occupational health and marine oil-spill response and is restricted to exposures to crude oil in its various forms. Thus in-situ burning of oil is included, but ancillary chemicals such as surfactants or bioremediation agents are not. The content of this chapter is largely based on the literature published after 1985, the date of a comprehensive review conducted by Politzer et al . [1985] for the American Petroleum Institute, and on a review carried out for the Marine Spill Response Corporation early in 1993 [Holliday and Park, 1993]. Concern about health and safety is a normal part of every oil spill. In general, safety is easier to understand and address than are concerns about exposure to crude oil and other chemicals which might be used in the response. At one level, human exposure can be addressed through the enforcement of very conservative requirements for the use of personal protective equipment (PPE). In the real world, however, conditions at a spill site make the use of such equipment inconvenient or even hazardous, and so the goal becomes to balance the risk from exposure with the appropriate level of PPE. While oil-spill cleanup is a comparatively new aspect of occupational-health practice, and dates from the formalization of response measures by companies and national and international agencies (something that occurred over the last 30 years), exposure to crude oil itself is a "mature" occupational-health matter. Workers have been exposed, both by inhalation and dermally, to the effects of crude oil for the past century. The exposure of response workers during the early phases of the oil-spill response can be likened to that experienced by oil-well-drilling crews and, to a lesser extent, by oil-well-maintenance personnel or fighters of oil-well fires. In contrast, exposures in the later stages of the cleanup are less clearly related to occupations within the oil industry. The crude oil will have been altered by weathering, and exposure to cleanup chemicals (e.g., dispersants, bioremediation agents) will become relatively more prominent. Such substances are beyond the scope of this chapter, and in any event, few data are available on the compositions or mammalian toxicity of dispersants. Although there are frequent references to toxicity in connection with dispersants, these invariably seem to refer to ecotoxicity. Human hazard does not appear to be an issue. For example, in a recently published paper entitled, "Effectiveness and safety of biosurfactants as agents of oil spill response" [Lepo et al., 1997], "safety" refers to possible toxicity to crustaceans and fish.

Introduction: In the aftermath of an oil spill, what should drive the cleanup response and when is it reasonable to stop cleaning? Further, which of the diversity of oil spill clean-up technologies as described in other chapters of this volume might be employed most effectively to achieve this elusive goal? These are complex questions involving chemical, ecological, socio-economic and political considerations and there are no simple answers. It is important to identify and build consensus for recommended clean-up protocols. These recommendations should be based on the considerable experience that has accumulated over the past 30 years. It is the intent of this paper to identify key points and issues with respect to ecological aspects, bearing in mind that these in turn commonly relate to socio-economic aspects.

Introduction: The use of chemical and biological agents (e.g. dispersants and bioremediation agents, respectively), as well as certain physical oil removal techniques (e.g. high-pressure, hot-water applications to oiled shorelines) during oil spill response operations requires consideration both of the gross effectiveness of such oil removal/displacement techniques and of the ecological impact of the response technique. Accordingly, the intent of response technology optimization requires the identification of suitable response agents, their application strategies, determination of mass oil removal effectiveness, and efficient coordination of alternative response strategies with conventional measures, all compared with traditional mechanical collection methods and evaluation or relative response ecological impacts. These issues often need to be examined in an experimental setting in order to acquire information required to make more effective decisions during oil spill response and cleanup operations. Controlled field studies that are designed to identify optimal response and clean-up strategies, while valuable for realism, are expensive and often difficult to implement because of regulatory barriers (Reilly et al., 1994)). Conversely, results from small scale laboratory testing do not incorporate sufficient environmental realism (variables and scale) to permit confident predictions about real-world situations. However, bounded and partly enclosed outdoor experimental units, or 'mesocosms', can closely simulate natural aquatic environments (Odum, 1984). Such test systems provide a simulation of real-world exposure without the costs of a controlled-release field study. Mesocosms can serve to bridge the gap between large-scale field experiments, with their inherent control difficulties, laboratory experiments which can be statistically replicated but suffer from a lack of environmental realism (Rodgers et al., 1996). Mesocosms have strengths and weaknesses depending upon system design. Therefore, the type of ecological research to be conducted will dictate the choice of mesocosm design. The following discussion presents design requirements and scientific considerations for mesocosm simulations of marine environments impacted by oil spills. Two existing mesocosm systems for marine oil spill ecological research in both pelagic and nearshore environments are reviewed in some detail - the Marine Ecosystem Research Laboratory (MERL) in Narragansett, Rhode Island, and the Coastal Oil-Spill Simulation System (COSS), in Corpus Christi, Texas.

Over the last 20 years, the development of operational procedures to accelerate the natural biodegradation rates of oil spilled on shoreline environments has been the focus of numerous research programs. As a result, bioremediation has been demonstrated to be an effective oil spill countermeasure for use in cobble, sand beach, salt marsh, and mudflat environments. Today, studies are directed towards improving the efficacy and evaluating the ecological impacts of available bioremediation agents and/or procedures. This review describes the latest developments in bioremediation strategies and their key success factors.

This chapter describes the state of knowledge regarding the most applicable countermeasures to deal with oil on, in or among ice. Countermeasures are discussed in the context of seasonal variations in ice conditions and observations of oil fate and behaviour in a variety of different situations. The behaviour of oil spilled in ice covered waters is governed largely by the ice concentration in the case of broken ice, and the processes of encapsulation and subsequent migration in the case of solid (fast) ice). Each season presents different drawbacks and advantages for spill response. During freezeup and breakup, drifting ice and limited site access tend to restrict the possible response options and significantly reduce recovery effectiveness. Mid-winter, although associated with long periods of darkness and cold temperatures, provides a stable ice cover that not only naturally contains the oil nearshore within a relatively small area but also provides a safe working platform for oil recovery and transport. For the case of spills under or on fast ice, there are a range of effective countermeasures options which can result in very high recovery effectiveness. Countermeasures to deal with spills in moving pack ice are much more limited and likely to result in highly variable recovery values depending on a variety of natural conditions and logistics constraints.

Introduction: Orimulsion is a fuel consisting of natural bitumen dispersed in fresh water (26% to 30%) which is stabilised (as a bitumen-in-water emulsion) by the addition of a small quantity of surfactant. The process of creating Orimulsion turns semi-solid bitumen with a viscosity of 10,000 mPas into a mixture with a viscosity of 450 mPas. The composition of Orimulsion makes it, at first consideration, seem an unlikely fuel. The combination of modern emission control, independence from the fluctuations in world crude oil prices and proven reserves of 1.27 trillion barrels (Middle East crude reserves are estimated at only 267 billion barrels) make this a significant energy source for the future. The typical composition of Orimulsion is given in Table 1. Orimulsion is clearly destined for increased consumption around the world and, with this, will inevitably come an increased risk of spillage and a requirement for appropriate spill control technologies. However, unlike conventional crude or fuel oils, we have no past spills or documented experiences to exploit. The development of containment and recovery systems must therefore rely on limited examinations of the product, and its fate and behaviour.

It has been estimated that some 6 million tonnes of crude oil is routinely transported by tankship around the world's oceans on a daily basis. Despite the introduction of stringent operating and safety regimes there remains the possibility of an incident occurring that could threaten the waters and shorelines of countries that are in the vicinity of these routes. Shipboard and international contingency plans assume a level of preparedness which may be limited in some of the countries that lay along these shipping lanes. Although the probability of significant oil pollution incidents occurring whilst the vessel is on the high seas is m minimal, they have occurred, some with considerable impact on the areas concerned. Whilst the majority of countries have some form of mutual aid and agreements in place and a number have access to equipment stockpiles, there are still a significant number of areas where there is heavy reliance on local resources. This paper addresses ways in which countries with limited resources can best be prepared for an oil spill and some of the challenges, which this entails.