Saturday, 29 January 2011

Oil Spills

REVISION May 1, 2000
Tarred beaches, dead and dying wildlife, damaged fisheries, contaminated water supplies. These are the short-term effects of an oil spill. In the long-term, toxic materials from oil can remain in the water and on the land for many years. They can build up in the food chain to lethal levels, and destroy or disrupt and area's ecosystem.
How Oil Spills Occur: Petroleum is used as a vehicle fuel, heating source for homes and industry, for electricity generation, and as a feedstock for the chemical industry. Because of the huge demand for oil, enormous quantities are moved from production areas to where the oil is used. Oil is pumped from the ground, refined, transported and stored. There are many steps in this process during which oil can spill from well heads, drill rigs, tankers, pipelines and storage tanks. Oil may leak from ocean-going ships during accidental and deliberate spills. Spills can happen on land or water when oil is incorrectly handled, there are railway or truck accidents, tankers or barges collide, the insides of tankers are washed, and when natural oil deposits seep.
Sometimes when people change the oil in their cars, they dump the used, dirty oil on the ground or down the storm sewer. The rain carries the oil with the metals and particles from the car engine into streams and creeks. If you added up all the oil dumped on the ground in a year, it would equal or surpass a serious oil tanker spill.
Natural Seepages: Not all spills are man-made. Crude oil is made by the earth from decayed plants and animals which lived millions of years ago. Oil has been in the environment for a long time. Some oil lies below the ocean floor and can seep into the ocean through cracks. As much as 1.5 million barrels of oil may enter the ocean from natural seeps each year. When these leaks occur, as when spills occur, natural organisms and chemical processes act to break down the oil over time. This process is called natural bio remediation.
What Happens When Oil Spills: When oil spills and mixes with water it can contaminate drinking water, kill fish and poison wildlife. Just one quart of oil may pollute up to 150,000 gallons of water! Oil is harmful to shellfish, finfish, marine mammals and waterfowl who live near the spill. Oil spills are ugly and are expensive to clean up. In addition, damage to fisheries places a hardship on those who make their living by fishing.
When oil enters the ocean it quickly begins to change and disperse. Though oil is toxic, it becomes less so with time. Winds and waves help spread and disperse the oil. Some oil will evaporate. Some will form into tar balls and sink to the bottom where they may remain for a long time, slowly releasing hydrocarbons into the water. Bacteria in the water attack and digest the oil. If people act quickly after the spill, they can scoop up some of the oil and stop it from causing worse damage to the environment.
Effects on the Food Chain: Each tier of the marine food chain can be affected by an oil spill. Oil floating on the water may contaminate plankton (very small, swimming or floating plants and animals). When small fish eat these plankton, they also eat the oil. Bigger fish, bears and humans who eat these fish will ingest oil too. Marine animals and birds can eat oil or it can get on their fur and feathers. When oil gets on a bird's feathers, the feathers lose their insulation capability and the bird can't adjust its body temperature and dies. Oil may obstruct the germination and growth of marine plants.
Cleaning Up Oil Spills: It is important to act fast to clean up an oil spill and prevent the oil from spreading to a bigger area. Spills can happen the open seas, close to shores, or in lakes, streams and rivers. Spills on land can contaminate groundwater or streams. How the spill is cleaned up depends on where it happened. In smaller bodies of water oil does not spread as much and cleanup is easier.
Oil floating on the surface can be held away from the shore by booms and cleared with skimmers. Booms are barriers that extend about three feet below the water surface. They are anchored near the shoreline. Booms intercept and contain the oil. Skimmers, such as vacuum machines or oil absorbent plastic ropes, are placed inside the boom to scoop up the oil. Booms and fences are often of little use in the open seas. They cannot contain a spill when there are big waves or strong currents. Once the oil is whipped into a froth called a mousse, skimming is difficult. Sometimes chemicals are used to speed the disposal of the oil into small globules that are more easily eaten by microorganisms.
When oil reaches the shoreline, it can be cleaned in several ways:
  • Manual pickup - hand tools are used to collect and bag oily materials. This method improves the appearance of the beaches.
  • Tarmat breakup / removal - tarmats, which are thick asphalt-like coverings of oil, are slow to degrade, can be broken with hand tools and then scattered or collected.
  • Tilling/raking - Oil that is under the surface is exposed by using a rake to turn over the topsoil. Raking or tilling helps in natural degradation or bioremediation (discussed below).
  • Spot washing - hand-held high pressure washing tools are used to remove small accumulations of oil. The runoff water is then collected.
Sometimes these techniques cannot remove all the oil trapped under rocks or in beach sediments. A technique called bioremediation has worked to remove underlying oil. Bioremediation involves covering the oiled area with "fertilizers" that contain microorganisms, like bacteria. These microorganisms speed the natural degradation processes already at work. It is thought that the more microorganisms at work, the faster the oil will be removed. Bioremediation is less disruptive to the environment than other techniques. It simply improves on nature's own way of destroying oil.
Several serious oil spills have brought attention to the damage that can result from oil spills. Three spill are discussed below.
The Persian Gulf War: Although the war in the Middle East in the early months of 1991 was brief, it left behind a damaged environment. Huge quantities of oil (2.5 to 4 million barrels) were dumped into the Persian Gulf. It was the largest oil spill in history. The oil may have destroyed or severely disrupted the area's marine ecosystem. The oil covered some 600 square miles of sea surface and blackened 300 miles of coastline. The waters of the Gulf contain coral reefs, mangrove swamps, and beds of sea grass and algae, as well as birds, sea turtles, fish and marine mammals. All these plants and animals were affected by the oil. Mangrove swamps and other kinds of wetlands are very sensitive to oil because their root systems are above water and can become coated or clogged with oil.
Because this oil spill happened during a time of war, clean-up actions were delayed. Efforts were made to protect a few delicate areas. If action could have been taken earlier, less oil would have gotten into the water. Booms and skimmers were set up and used to protect some areas. People from all over the world went to the area to help with the cleanup.
The Exxon Valdez: The worst spill in U.S. history occurred in March 1989 when the supertanker, Exxon Valdez, ran aground in Prince William Sound, Alaska. About 11 million gallons (260,000 barrels) of oil spilled from the tanker. It spread out to 900 miles of shoreline. This shoreline and neighboring islands are home to deer, bears, seals, otters, whales, birds and fish, and other plants and animals.
This was the first large spill in an enclosed, cold body of water. These conditions made clean-up very difficult. The oil slick spread quickly. Chemical dispersants could not be used because the seas were too calm for them to be effective. Then high winds drove the oil into a mousse. In the months following the spill, workers collected more than 36,000 oiled birds and more than 1,000 sea otters. The number killed was several times the number found. Some people say that it will be 20 to 70 years before the seabird population fully recovers. Cleanup costs of this spill exceeded $2 billion. The cleanup involved more than 10,000 people, several hundred boats and aircraft, and special equipment.
The Monongahela River Spill: About a million gallons of oil accidentally spilled into the Monongahela River in Western Pennsylvania when an above-ground oil storage tank collapsed January 2, 1988. In a matter of seconds, a 30 foot wave of heavy oil surged over containment barriers and spilled into the river, threatening the water supplies of more than a million people living downriver. Swift action was necessary to safeguard these water supplies. Thousands of feet of booms were used to contain the oil as workers pumped it into barges and tanker trucks. Even with this massive cleanup effort, eight water suppliers in three states were forced to shut their intake for a few days.
Oil Spill Laws: Many governments have laws regulating oil spills. In the United States, spills of oil and other chemicals must be reported to the National Response Center at 1-800-424-8802 so action can be taken to contain the spill and clean it up to reduce pollution. Many states and local governments have similar laws.
We may not know for years, if ever, how much damage oils spills cause. Sometimes we don't know a lot about the area where the spill occurred. This makes it hard to know what affect the oil had. Finding ways to prevent the spills from occurring is important. In the United States, oil storage tanks are regulated to try to prevent future leaks. The USEPA regulates Underground Storage Tanks (USTs) and requires replacement of old tanks, corrosion protection for new tanks and pipes, and leak detection systems for tanks. After the Monongahela spill, some governments, such as Pennsylvania, passed laws requiring Aboveground Storage Tanks (ASTs) to be inspected and built to modern technical standards to reduce future leaks.
The U.S. Congress enacted the Oil Pollution Act of 1990 which makes the Marine Spill Response Corporation (MSRC) the official response group for oil spills from oil tankers. The bill also requires that oil tankers have double hulls by the year 2010. Although these double hulls are expensive, it is believed they will keep oil from escaping into the ocean. Some large oil companies are now building ships with double hulls. The law also provides money for quick response teams in the 10 U.S. Coast Guard districts.
What You Can Do: It may seem like you cannot do anything to stop oil spills. But you can. If you see an oil spill, report it to the government as soon as possible. Less oil is used when people conserve energy by driving smaller cars, using public transportation or alternatively-fueled vehicles or other ways of travel, like walking and bicycling. Instead of dumping used car oil on the ground or down a sewer, people can take the oil to certain service stations to be disposed of properly or recycled. If you change you own oil in you car, make sure you place a container on the ground under the engine to catch any spills. An old cookie sheet works well. Also, people can conserve energy in their homes, too.
If everyone used less oil, fewer tankers would sail the seas. This could reduce the risk of oil spills.