Most Devastating Human Caused Environmental Disasters Biology Essay


The Exxon Valdez oil spill occurred in the Prince William Sound, Alaska, on March 24, 1989. It is considered one of the most devastating human-caused environmental disasters ever to occur at sea. As significant as the Valdez spill was, it ranks well down on the list of the world's largest oil spills in terms of volume released. However, Prince William Sound's remote location (accessible only by helicopter and boat) made government and industry response efforts difficult and severely taxed existing plans for response. The region was a habitat for salmon, sea otters, seals and seabirds. The vessel spilled 10.8 million U.S. gallons (about 40 million litres) of Prudhoe Bay crude oil into the sea, and the oil eventually covered 1,300 square miles (3,400 km) of ocean. This research report will discuss the cleanup, the damage, and the results of the biggest oil spill in United States history.


During the 1960's the oil industry established the Alyeska consortium made up of the Seven Sister Oil companies. They began construction on the Alyeska pipeline in order to transport the crude extracted from remote regions of Alaska's North Slope to Port Valdez where it could be loaded into oil tankers and delivered to the hungry 48 states below. The Exxon Valdez, after receiving 53 million cargo of crude, pulled away from the Valdez pipeline terminal at 9:26 P.M., on its 28th trip out of the sound since its construction in 1986. The trip to Long Beach California, its destination, was to take five days and a half days.

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The Exxon Valdez is one of the largest vessels on water. Almost a thousand feet long, it moves with tremendous force through the water. At its top speed of 15 miles per hour it would take 3 miles for it to come to a halt. On board that night was Captain Joseph Hazelwood, a harbor pilot, and third mate Gregory Cousins. Once the harbor pilot had safely guided the huge vessel through Valdez Narrows and past Rocky Point he departed, and left the tanker in the command of Captain Hazelwood.

Although the weather that night was conducive to traveling, some small icebergs (growlers) had drifted into the sound from the Columbia Glacier. Captain Hazelwood radioed to the Coast Guard station that he would be changing course in order to avoid the growlers. Growlers are chunks of ice from glaciers which make a growling sound when knocked against the ship's hull. The captain received permission to move into the northbound lane. Before retiring to his cabin, Captain Hazelwood instructed his third mate Gregory Cousins to steer the vessel back into the southbound lane once it passed Busby Island. Although Cousins did give the instructions to the helmsman to steer the vessel to the right, the vessel was not turning sharply enough and at 12:04 a.m. the vessel hit Bligh Reef. It is not known whether Cousins gave the orders too late, the helmsman did not follow instructions properly, or if something was wrong with the steering system of the vessel.

The impact was so forceful that it ripped through its cargo tanks, spilling tons of oil into the sound so quickly that it created waves of oil three feet above water level. Hazelwood, attempting to get the vessel loose from the reef did not phone the Coast Guard until twenty minutes after the collision, finally gave up maneuvering the vessel nearly two hours later.

All told, over 11 million gallons of oil leaked out into the Prince William Sound creating the worst oil spill in American history. One of the conditions on which the Trans Alaska Pipeline was constructed was that Alyeska submit an oil spill response plan. According to that plan, Alyeska would be at the site with response equipment within five hours of the spill. However, at the time of the Valdez spill, little of the oil-containment equipment was ready and the barge which should have much of the equipment already on it sat nearly empty. It would be ten hours before clean up crews would arrive, at this point the oil slick had spread for miles.

The weather was also uncooperative for an effective early clean up. Additionally, waters were too calm to use oil clean-up chemicals called "dispersants" which are sprinkled on the water by airplane. Dispersants break up the oil and work best in rough seas where they spread and foam, like dishwater soap. When the seas finally started behaving, the skies were much too stormy for planes to fly and spread dispersants. By the third day, the slick had covered 100 square miles and was spreading. There were simply not enough containment booms to prevent the oil from spreading. The amount of oil was overpowering.

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Perhaps the most interesting, effective, and technologically advanced method of clean up is bio-remediation. This is a process whereby the chemicals nitrogen and phosphorous are sprayed on oil contaminated soil and rocks. These chemicals then act as a catalyst to the growth of micro-organisms naturally protecting the environment which break down oil. This technique could actually double the speed of natural oil removal.

The purpose of this research report is to discuss the Exxon Valdez oil spill from several different aspects.  In a broad sense it did tremendous amounts of damage to Prince Williams Sound, but that was only the beginning.  The spill affected the ocean, the animals, prevention for future oil spills, response competence, and created awareness for these problems throughout the world.  We will explain the reason the spill occurred, what affects it had on the ecosystem, what has been done to solve the problem, and why it was the most exposed and studied environmental tragedy.

Examine the aim and objectives of Exxon Mobil Corporation.

Exxon Mobil Corporation is committed to being the world's premier petroleum and petrochemical company. They continuously achieve superior financial and operating results while adhering to the highest standards of business conduct. These unwavering expectations provide the foundation for their commitments to those with whom they interact:


Exxon Mobil Corporation is committed to enhancing the long-term value of the investment dollars entrusted to us by their shareholders. By running the business profitably and responsibly they expect their shareholders to be rewarded with superior returns. This commitment drives the management of their company.


Exxon Mobil Corporation success depends on their ability to consistently satisfy ever-changing customer preferences. They pledge to be innovative and responsive, while offering high quality products and services at competitive prices.


The exceptional quality of their workforce is a valuable competitive edge. To build on this advantage they will strive to hire and retain the most qualified people available and maximize their opportunities for success through training and development. They are committed to maintaining a safe work environment enriched by diversity and characterized by open communication, trust, and fair treatment.


Exxon Mobil Corporation pledge to be a good corporate citizen in all the places we operate worldwide. They will maintain the highest ethical standards, obey all applicable laws and regulations, and respect local and national cultures. Above all other objectives, they are dedicated to running safe and environmentally responsible operations.

To be successful, ExxonMobil must be at the leading edge of competition in every aspect of our business. This requires that the Corporation's substantial resources - financial, operational, technological, and human - be employed wisely and evaluated regularly.

While they maintain flexibility to adapt to changing conditions, the nature of their business requires a focused, long-term approach. They will consistently strive to improve efficiency and productivity through learning, sharing and implementing best practices. They will be disciplined and selective in evaluating the range of capital investment opportunities available to us. They will seek to develop proprietary technologies that provide a competitive edge.

They will achieve their goals by flawlessly executing their business plans and by strictly adhering to these guiding principles along with their more comprehensive Standards of Business Conduct.

Carefully observe the oil and refinery industrial processes and operations.

The oil refining process are once discovered, drilled and brought to the earth's surface, crude oil is transported to a refinery by pipeline, ship or both. At the refinery, it is treated and converted into consumer and industrial products.

Three major refinery processes change crude oil into finished products:




Separation - heavy on the bottom, light on the top

The first step is to separate the crude oil into its naturally occurring components. This is known as separation and is accomplished by applying heat through a process called distillation.

Separation is performed in a series of distillation towers, with the bottom product from each tower feeding the next. A furnace in front of each distillation tower heats and vaporizes the crude oil mixture. The vapor and liquid mixtures is then fed into the bottom section of the tower. The feed section is the hottest point in the distillation tower and can reach as high as 750 degrees Fahrenheit.

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Components that are still liquid at this elevated temperature become the tower's bottom product. Components that are in vapor form rise up the tower through a series of distillation stages. The temperature decreases as the vapors rise through the tower and the components condense.

The "yield" from a distillation tower refers to the relative percentage of each of the separated components; know as "product streams". This will vary according to the characteristics of the crude being processed. Because a liquid's boiling point decreases at lower pressures, the final distillation steps are performed in a vacuum to maximize liquid recovery. Products from the distillation tower range from gases at the top to very heavy, viscous liquids at the bottom. In all cases, these product streams are still considered "unfinished" and require further processing to become useful products.

Conversion - cracking and rearranging molecules to add value

Distillation separates he crude oil into unfinished products. However, the products do not naturally exist in crude in the same proportions as the product mix consumers demand. The biggest difference is that there is too little gasoline and too much heavy oil naturally occurring in crude oil. That is why conversion processes are so important. Their primary purpose is to convert low valued heavy oil into high valued gasoline.

All products in the refinery are based on the same building blocks, carbon and hydrogen chains, which are called hydrocarbons. The longer the carbon chain, the heavier the product will be. Converting heavier hydrocarbons to lighter hydrocarbon can be compared to cutting a link on a steel chain to make two smaller chains. This is the function of the Fluidized Catalytic Crackers (FCCs), Cokers and Hydrocrackers. In addition to breaking chains, there are times when we want to change the form of the chain or put chains together. This is where the Catalytic Reformer and Alkylation are necessary. Specialized catalysts are of critical importance in most of these processes.

The FCC is usually the key conversion unit. It uses a catalyst (a material that helps make a chemical reaction go faster, occur at a lower temperature, or comtrol which reactions occur) to convert gas oil into a mix of Liquified Petroleum Gas (LPG), gasoline and diesel. The FCC catalyst promotes the reaction that breaks the heavier chains in the right place to make as much gasoline as possible. However, even with the catalyst, the reactions require a lot of heat; therefore the FCC reactor operates at about 1,000 degrees Fahrenheit.

The Heaviest material in the refinery is Vacuum Tower Bottom (VTB) or "resid". If allowed to cool to room temperature, it would become a solid. Some resid is actually sold into the paving asphalt market as a blend component. Resid is too heavy and has too many contaminants to process in the FCC. The Delayed Coker is used to convert this heavy material into more valuable products. The delayed coker uses high temperature to break the hydrocarbon chains. Delayed coking reactions are less selective than FCC reactions. Delayed coking also produces a relatively low valued petroleum coke as a by-product.

In some refineries, the FCCs and Delayed Cokers are supplemented by Hydrocracking. Similar to the FCC, the Hydrocracker uses high temperature and a catalyst to get the desired reactions. In Hydrocracking, the catalyst stays in one place and the gas oil passes over the catalyst, whereas in the FCC the catalyst is much finer and moves together with the gas oil. The catalyst compositions differ. In Hydrocracking, the reactions take place at high temperatures in the presence of high concentrations of hydrogen. The Hydrocracker produces products with low sulfur levels. The light liquid product can be sent directly to Catalytic Reforming and the other liquid products can be blended directly into jet fuel and diesel.

The conversion processes that have been discussed up to this point have focused on reducing the length of some hydrocarbon chains. However, there are other hydrocarbon chains that are too short. Butane is produced as a byproduct of other conversion units. The Alkylation Unit (Alky) takes two butanes and combines them into a longer chain using a catalyst.

The last conversion process is Catalytic Reforming. The purpose of the reformer is to increase the octane number of gasoline blend components and to generate hydrogen for use in the refinery hydrotreaters. The same length carbon chains can have very different octane numbers based on the shape of the chain. Straight chains, or paraffins, have a relatively low octane number, while rings, or aromatics, have high octane numbers. At high temperatures and in the presence of hydrogen, the catalyst will "reform" paraffins into aromatics, thus the name catalytic reforming. Some of the aromatics produced are sent to petrochemical manufacturers, where they are converted to plastics and fabrics.


Once crude oil has been through separation and conversion, the resulting products are ready for purification, which is principally sulfur removal. This is done by Hydrotreating, a process similar to Hydrocracking but without converting heavy molecules into lighter ones. In Hydrotreating, unfinished products are contacted with hydrogen under heat and high pressure in the presence of a catalyst, resulting in hydrogen sulfide and desulfurized product. The catalyst accelerates the rate at which the sulfur removal reaction occurs. In each case, sulfur removal is essential to meeting product quality specifications and environmental standards. Other units in the refinery remove sulfur, primarily in the form of hydrogen sulfide, through extraction, which is a second method of purification. Whether through hydrotreatment or extraction, desulfurization produces hydrogen sulfide. Sulfur recovery converts hydrogen sulfide to elemental sulfur and water. The residual sulfur is sold as a refinery by-product.

End Products, Modern refinery and petrochemical technology can transform crude oil into literally thousands of useful products. From powering our cars and heating our homes, to supplying petrochemical feedstocks for producing plastics and medicines, crude oil is an essential part of our daily lives. It is a key ingredient in making thousands of products that make our lives easier - and in many cases - help us

Oil refining process chart

Evaluate the risks in all areas that lead to the oil spill disaster and pollution.

There are multiple factors have been identified as contributing to the oil spill disaster and pollution.

Exxon Shipping Company failed to repair the Raycas radar system, which would have indicated to the third mate an impending collision with the Bligh reef. The third mate failed to properly maneuver the vessel, possibly due to fatigue or excessive workload. Exxon Shipping Company also failed to supervise the master and provide a rested and sufficient crew for Exxon Valdez.

In light of the above and other findings, investigate reporter Greg Palast stated in 2008 "Forget the drunken skipper fable. As to captain Joe Hazelwood, he was below decks, sleeping off his bender. At the helm, the third mate never would have collided with Bligh Reef had he looked at his RAYCAS radar. But the radar was not turned on. In fact, the tanker's radar was left broken and disabled for more than a year before the disaster, and Exxon management knew it. It was just too expensive to fix and operate. Exxon blamed Captain Hazelwood for the grounding of the tanker. Other factors as below:

The oil industry promised, but never installed, state-of-the-art iceberg monitoring equipment.

Exxon Valdez was sailing outside the normal sea lane to avoid small iceberg thought to be in the area.

The 1989 tanker crew inspections in Valdez were not done, and number if staff were reduced.

Tanker crews were not told that the previous practice of the Coast Guard tracking ships out to Bligh reef had ceased.

Lack of available equipment and personnel hampered the spill cleanup.

Critically identify the consequences of all the hazards of the oil spill disaster.

There are four impact of the oil spill disaster. Impact on fauna, impact on fishing, impact on humans and impact on follow up.

Impact on fauna

Between 3,700 and 5,800 mammals of 9 different species were affected by the pollution. 300 cases of direct mortality of seals were reported, mainly caused by breathing in volatile fractions of the oil. Some 2,800 otters died of smothering, ingestion of oil and hypothermia. 14 of the 36 killer whales counted in the sound before the spill disappeared between 1989 and 1990. Considerable efforts were made to direct deer and bears towards unpolluted areas to prevent them from consuming contaminated substances. No less than 71 species of seabirds were affected. Guillemots were especially heavily hit, with some 22,000 corpses collected. The total number of seabirds killed by the oil spill is estimated at between 250,000 and 350,000. The bald eagle, emblem of the United States of America, was no exception: 153 corpses were recovered. Some 1,630 alive oiled birds were sent to 4 rehabilitation centres and 837 of them were released after treatment. The cost of this operation was estimated at $25.3 M (over $30,000 per saved bird). A very high invertebrate mortality rate was recorded around the oil tanker during the 2 weeks following the spill: almost all crustaceans disappeared and other invertebrates became rare. Heavy losses were incurred by certain species living on the foreshore, in particular winkles and limpets. Several thousand dead fish were observed during the same period, a relatively low impact in comparison to other groups. However, few fish escaped non-lethal effects, such as erosion of fins and/or the accumulation of oil in the gills and reproductive organs.

Impact on fishing

Fishing in Alaska involves some 12,000 fishermen. Landings in the fishing harbours of Prince William Sound reached $174 M in 1987, almost 6% of the American market. The herring fishing season opens at the beginning of April and represents an annual sum of around $14 M. The pink salmon fishing season opens in June/July and brings in some $33 M on a yearly basis. Immediately after the spill, the Alaskan Governor issued a fishing ban for Prince William Sound to prevent cutting back the populations of fish which had survived the pollution. 4,000 jobs in the fishing industry were affected. A risk assessment study on consumer health was carried out based on the analysis of hundreds of samples of fish and molluscs. The risk of cancer connected to the consumption of sea produce from areas affected by the oil spill appeared to be negligible. This data did not however satisfy everyone: the year following the spill, a study conducted to assess changes in eating habits within the native population reported a significant decrease (from 31% to 77%) in the consumption of seafood in 10 of the 15 villages studied. During the second and third year following the spill, subsistence fishing resumed in all but a few families.

Impact on humans

One year after the spill, a study assessed the frequency of psychiatric symptoms and the association of these symptoms with the level of exposure to the oil spill and to clean-up operations. Exposure was significantly associated with the occurrence of general anxiety, post-traumatic stress syndrome and depression. These results showed that the hypothesis of a link between the oil spill and an increase in psychiatric problems within the population living in the affected areas was plausible. Women and natives of the polluted area seemed to be the most at risk.

Impact on follow up

Prince William Sound is lined with a rugged coastline punctuated with numerous fjords, islands and reefs. The affected area is considered to be ecologically sensitive. The Exxon Valdez Oil Spill Trustee Council (EVOSTC), created the summer following the spill, aimed to contract and coordinate environmental follow-up, impact assessment and restoration of damages inflicted on the environment. In 1994, it adopted a 5-fold plan of action:

surveillance of the main resources and species affected

restoration of sites

protection of habitats

management of a long term reserve fund

scientific coordination, administration and communication.

A large number of studies were thus conducted within this framework. Only seals, killer whales and otters were studied on a long term basis, as the state of their populations was considered a major concern. The year of the incident, the reproduction of bald eagles recorded a failure rate of 85% for heavily or moderately polluted areas, compared to 55% for lightly polluted to unpolluted areas. This rate returned to normal in 1990. It finally became evident that the spill had not significantly affected the population. As for species of commercial value, studies mainly concentrated on herring and pink salmon, highlighting a drastic fall in the return of adult salmon in 1990 and in the herring population in 1993.

What are the improvements and changes in the management systems so to prevent the disaster from happening?

In the aftermath of the Exxon Valdez accident, ExxonMobil redoubled its long-time commitment to safeguard the environment, employees and operating communities worldwide. To improve oil-spill prevention, ExxonMobil has, for example:

Modified tanker routes

Instituted drug and alcohol testing programs for safety sensitive positions

Restricted safety-sensitive positions to employees with no history of substance abuse

Implemented more extensive periodic assessment of ExxonMobil vessels and facilities

Strengthened training programs for vessel captains and pilots and

Applied new technology to improve vessel navigation and ensure the integrity of oil containment systems

 In the event a spill occurs, we also have improved our response capability. For example:

ExxonMobil is a founding member of every major oil spill response center worldwide

There are over 1,000 ExxonMobil employees involved in oil spill response teams worldwide

We hold frequent, extensive oil spill drills at various ExxonMobil locations around the world and

We have developed and applied new spill-detecting technology.

Prevention is the principal defense against oil spills. The old adage that an ounce of prevention is worth a pound of cure remains valid: the best way to protect the environment is to prevent spills from occurring in the first place. This truth is vividly evident in the enormous costs of the Exxon Valdez oil spill.

Although both government and industry have critical roles to play, prevention of oil spills cannot be accomplished without industry action to safeguard oil transport. Industry immediately should review all elements of the oil transportation and distribution system for vulnerabilities that could lead to serious oil spills. It is industry's responsibility to ensure that facilities and equipment are properly designed, safely operated, and correctly maintained.

Industry already has taken steps in an attempt to reduce the risks of oil spills. The American Petroleum Institute has undertaken a review of industry operations and will report a recommended program in three months. The review will examine manning of ships, as well as preparedness and response issues. The major owner companies of the Alyeska Pipeline also have announced plans to improve the industry's ability to prevent oil spills in Alaskan waters.

Human error is a major factor in many types of accidents. Any comprehensive prevention program must address human error through better training and equipping of personnel, safety programs, and steps to ensure that constant vigilance is exercised by management. For example, legislation, regulation, and studies under consideration address ways to prevent drug and substance abuse in the workplace. Prevention of such abuse is especially important for vital transportation services.

Government also must take steps to help prevent oil spills. Federal and state agencies currently are conducting investigations to address the cause of the accident. These investigations will examine whether navigation controls were adequate. They will look into licensing of the captain and crew and issues of negligence, liability, and criminal violation. Results from these investigations can have an important impact on preventing future oil spills.


The disaster of the Exxon Valdez reminds us that the oil business has long been a hazardous, dangerous and potentially messy one, fraught with uncertainties and the possibility for catastrophe, the echoes of which reverberate even today in the Gulf of Mexico, 4400 miles and 21 years away.

Oil firms like Exxon should realize that the effects of a single oil spill can be devastating for people, animals, marine life, and the environment for a long, long time. Considering this, the managers of oil firms should be aware of the recommendations and suggestions like that government bodies and non-profit environmental organizations give in this regard. This is the ethical and professional responsibility of all oil firms, especially those that transfer oil in bulk volumes. A proper system should be made to educate all concerned employees about the consequences of oil spills on humans, animals, and environment. Similarly, all employees should know how they can play their part in preventing oil spills. This should be given top priority and formal training should be given to employees regarding this matter. Finally, the top management should personally administer the implementation of oil spill prevention strategies and actions.

One more thing is that although firms have contingency plans, they rarely practically test such plans. It is necessary to test contingency plans to see if they are still effective or not. In addition, as technological and environmental changes occur, such plans should be revised accordingly to reflect the latest techniques that can be used to control oil spills. The recommendations of government and non-profit environmental organizations should be utilized here too. Oil spill prevention and control procedures must be formally defined by oil firms as these steps will more likely stop oil spills from happening.