Oil Spills
Oil is one of the world's most important fuels. Its uneven distribution on the planet, however, forces its transport over the high seas and through pipelines to distant lands. This inevitably results in accidents, some massive and some small, during drilling and transporting. In 1967 the 118,285-ton supertanker Torrey Canyon, carrying oil from Kuwait, caused the world's first massive marine oil spill off the coast of England.
Oil spills are a dramatic form of water pollution—visible, immediate, and sometimes severe. The sight of dead and dying otters and birds covered with black film arouses instant sympathy, and the bigger the spill, the more newsworthy it is. While it is true that oil can have a devastating effect on marine life, the size of the spill itself is often not the determining factor in the amount of damage it causes. Other factors include the amount and type of marine life in the area and weather conditions that would disperse the oil. Despite its drama, however, worldwide pollution from tanker spills is a relatively minor source of marine pollution. It represents a small fraction of the oil released to the environment worldwide when compared to industry sources, non-tanker shipping releases, and oil seepage from natural sources.
When the Exxon Valdez ran into a reef in Prince William Sound, Alaska, in March 1989, eleven million gallons of oil spilled into one of the richest and most ecologically sensitive areas in North America. A slick the size of Rhode Island threatened fish and wildlife. Otters died by the thousands, despite efforts by trained environmentalists and local volunteers to save them. Oil-soaked birds lined the shores, only to be eaten by larger predator birds, which then succumbed to dehydration and starvation because the ingested oil destroyed their metabolic systems.
OCEAN POLLUTION ACT OF 1990.
In response to the Exxon Valdez disaster, Congress passed the Oil Pollution Act of 1990 (OPA; PL 101–380). The majority of the OPA provisions were targeted at reducing the number of spills and reducing the quantity of oil spilled. Among its provisions were the creation of a $1 billion cleanup-damage fund (the money comes from a tax on the petroleum industry), advance planning for controlling spills, stricter crew standards, and the requirement that new tankers have double hulls. When equipped with two hulls, if the tanker's exterior hull is punctured, the interior hull holding the oil may still remain intact. (The Exxon Valdez was not double-hulled.) The law requires older tankers to be fitted with double hulls by 2010. The OPA also:
- Compels the use of escort tugboats in certain harbors to assist tankers.
- Requires standards for tank levels and pressure-monitoring devices to detect leaks in cargo tanks.
- Requires the Coast Guard to establish minimum standards for overfill devices to prevent overfill oil spills. (An overfill oil spill is the result of too much oil being pumped into a tanker during a transfer from a facility to a tanker or between two tankers. On occasion, overfill spills have involved large quantities of oil.)
The issue of continuing danger from older, single-hulled oil tankers on the seas was highlighted in testimony before the U.S. Senate Committee on Commerce, Science, and Transportation on January 3, 2003. Robert N. Cowen, senior vice president and chief operating officer of Overseas Shipholding Group, Inc., spoke of the need for the United States to prevent these vessels from trading to the United States. Cowen described the November 19, 2002, sinking of the oil tanker Prestige (which was carrying 77,000 tons of heavy fuel oil) off the coast of Spain. He pointed out that cargo from the Prestige continues to wash up on the coastline of Galicia, Spain, where it pollutes sensitive fishing grounds. In addition, the cargo is washing ashore in the Landes region near Bordeaux, France. Moreover, Cowen stated that the governments of Spain, France, and Portugal have moved to ban substandard tonnage from their waters. According to Cowen, the United States continues to allow these older tankers to come into United States waters to trade. Cowen asked the Senate to ensure that restrictions are enacted to prevent older, single-hulled vessels from trading to the United States.
DECLINES IN OIL SPILLS.
Declines in oil spills are being seen on a global scale. The International Tanker Owners Pollution Federation data show that between 1970 and 1979 the incident rate for large spills (more than 5,000 barrels) from the worldwide tanker industry was 24.2 spills per year. Between 1980 and 1989 that rate dropped to 8.9 spills per year. From 1990 to 1999 the global spill rate declined further, to 7.3 spills per year.
The decline in oil spills in the United States is even more dramatic. About ten million barrels (420 million gallons) of oil per day are delivered into the United States by ship. According to the U.S. Coast Guard, the incident rate of large spills in the United States since 1991 has been 0.5 spills per year. There were no large spills in U.S. waters in the period 1991 to 2000 (the latest data available).
The Coast Guard data also show that the amount of oil spilled by tankers has decreased dramatically. The total amount spilled in U.S. waters in 1990 was about 115,000 barrels; from 1991 to 2000 the total number was less than 8,000. In 1997 the number of barrels of oil spilled was the lowest ever since the Coast Guard began keeping its records in 1973. More than three-fourths of the 1997 spills were less than ten gallons—less than a car's fuel tank holds.
Although oil tanker spills are highly visible cases of pollution entering the oceans, the EPA estimated that only about 5% of the oil entering marine waters is the result of oil tanker spills. The Coast Guard estimates conclude that water and sewage treatment plants in the United States discharge twice as much oil each year as oil tankers spill. Other sources of oil entering marine waters include the oil from street runoff, industrial liquid wastes, recreational boats, commercial fishing vessels, and intentional discharge from ships flushing their oil tanks.
CLEANING UP OIL SPILLS.
Left alone, oil spills will eventually disappear as natural processes break down the oil. (See Figure 6.9.) If nothing is done, oil will "weather" naturally. Turbulent wave action and sunlight will break it down both chemically and physically. Within twenty-four to forty-eight hours, the most toxic portions of the oil will evaporate, posing less of a threat to wildlife. As the oil breaks up into smaller droplets, it is more easily attacked and digested by naturally occurring microbes, which will break it down into harmless substances. Human intervention to speed up this process can be more or less successful, depending on the spill size, its location, and the weather conditions. There are two basic approaches to cleaning up oil spills: use of dispersants and use of bioremediation agents. Two important differences exist in the way they work. One difference is the mechanism by which they clean up the oil. The other is where and how they are used. Recent research suggests that the best solution may be to use both techniques depending on the characteristics of the site.
Dispersants are products that are applied to the water surface to break up surface oil slicks and facilitate the movement of oil particles into the water column. Dispersants bind to oil on the water surface so that the oil can mix and disperse into the water, similar to the way grease and oil on dirty dishes bind to detergent so that the oil and grease can be washed away in rinse water. Scientific evidence suggests that dispersed oil is broken down more quickly than undispersed oil. This is believed to be caused by the increase in the total surface area of the oil in a slick due to dispersants breaking the slick up into small droplets and making it more vulnerable to breakdown by natural processes such as weathering and biodegradation (breakdown by microbes).
Bioremediation is the process by which microbes eat oil molecules by breaking down their long hydrocarbon chains. Bioremediation agents are almost always applied to residual oil on shorelines for long-term cleanup situations. Usually, heavy oil is first removed before bioremediation is attempted. Bioremediation agents act to speed up the biodegradation of the petroleum molecules, a process that would occur naturally anyway.
There are three types of bioremediation: nutrient enrichment, use of genetically engineered microorganisms
FIGURE 6.9
Schematic of physical, chemical, and biological processes that break down oil
Although genetically engineered microbes have been successfully used under controlled conditions in ground-water and other land-based hazardous waste sites, there has been no scientifically validated demonstration of their successful use in oil spill cleanup. The reported success of this approach in the aftermath of the explosion of the tanker Mega Borg off the Texas coast in 1990 has not been scientifically substantiated. Many scientists believe that the fire associated with this tanker explosion was the primary factor in the rapid breakdown and disappearance of the spill.
A new bioremediation technique that is gaining credibility is increasing the availability of oxygen to the naturally occurring oil-eating microbes. Oxygen availability is increased through the addition of special chemicals or tilling the oiled substrate. Tilling breaks the oiled surface into smaller units and increases the exposure of these surfaces to the air (oxygen), making the oil more vulnerable to microbe attack.
Marine Debris
Marine debris is trash and garbage floating on the ocean or estuaries and washed up on beaches. Beaches and shorelines of U.S. estuaries and oceans are littered with debris carried to shore by the wind and tides. The effects of marine debris can be both costly to coastal communities and very dangerous to humans and aquatic life.
According to NOAA's online Ocean Report (http://www.publicaffairs.noaa.gov/oceanreport/index.html), marine debris is a major problem on beaches and in coastal waters, estuaries, and oceans. The report states that 80% of debris is washed, blown, or dumped from shore, while 20% is from recreational boats, ships, fishing vessels, and ocean platforms. The problem is exacerbated by the fact that most marine debris, such as cigarette butts, soda cans, plastic bags, and fishing gear, is man-made and slow to degrade. Some studies have shown that marine debris threatens more than 265 different species of marine and coastal wildlife through entanglement, smothering, and interference with digestive systems.
Certain types of marine debris, such as broken glass and medical waste wash-ups, can pose a serious threat to public health, causing beach closures and swimming advisories and robbing coastal communities of significant tourism dollars.
NOAA's Ocean Report cited these reasons for the persistence of marine debris:
- Implementation of effective marine debris control measures is currently hampered by a lack of consistent monitoring and identification of sources of debris.
- Implementation and enforcement of local anti-litter regulations and management of debris entering and exiting sewer systems are inadequate to effectively address the marine debris problem.
- Marine debris can be the result of small-scale pollution by individuals who consider their discharges or littering to be of negligible impact compared with large-scale polluters. However, the cumulative impact of continuous, small-scale pollution can be dramatic.
- Plastic makes up about 60% of the debris found on beaches. The increase in the use of various kinds of plastic as durable, lightweight packaging has heightened the need for proper management and disposal.
MEDICAL WASTE.
Trash that is washed up with the tide routinely litters beaches on both sides of the North American continent. In the summers of 1988 and 1989, medical refuse, such as syringes and blood vials, was found on ocean and estuarine beaches along many areas of the East Coast. Occurring about the same time as the growing public concern over AIDS and other needle-transmitted diseases, these occurrences provoked a public outcry for action. In response, Congress passed the 1988 Medical Waste Tracking Act (PL 92–532). The Act holds producers of medical waste accountable for safe disposal of the waste, or they risk penalties of up to $1 million in fines and five years in prison.
In 1990 the Agency for Toxic Substances and Disease Registry (ATSDR), a division of the U.S. Department of Health and Human Services, concluded that medical waste presents little danger to the general public. According to Dr. Maureen Lichveld, senior medical officer at the agency and coordinator for the research project, hospital medical wastes disposed of in the oceans represented no particular risk. The most pressing concern for future medical waste disposal comes from in-home health-care products used by people with chronic diseases, outpatient AIDS victims, and nursing homes. Subsequent studies by the Marine Conservancy, a private environmental group, indicated that medical waste accounts for only 0.01% of all waste washed up on the nation's beaches.
CRUISE SHIPS.
In July 1999 Royal Caribbean, one of the world's largest cruise lines, pleaded guilty in federal court to dumping oil and hazardous chemicals in U.S. waters and lying about it to the Coast Guard. They agreed to pay a record $18 million fine for polluting waters. This was in addition to the $9 million in criminal fines the company agreed to pay in a previous plea agreement. Six other cruise lines have pleaded guilty to illegal waste dumping since 1993 and have paid fines of up to $1 million. These cases have focused attention on the difficulties of regulating the fast-growing cruise-line industry, as most major ships sailing out of American ports are registered in foreign countries.
The luxury associated with cruise ships generates a lot of waste, much of which is reportedly disposed of through ocean dumping. In response to a petition from the Blue-water Network in 2000 on behalf of fifty-three organizations committed to protecting the oceans, the EPA is currently assessing cruise-ship discharges to U.S. waters. Among other things, the petition asks the EPA to:
- Quantify the volume of all waste streams such as sewage, garbage, fuel, and medical wastes from large passenger vessels and assess the adequacy of existing regulations to control the waste streams.
- Provide scientific assessment of the effects of the wastes on water quality, the marine environment, and human health.
- Identify options for a comprehensive monitoring, record keeping, and reporting regulation for all pollutants discharged into U.S. waters and wastes offloaded at U.S. ports from large passenger vessels.
- Evaluate the effect of repealing the National Pollutant Discharge Elimination System permit exemption for cruise ships and requiring them to have discharge permits.
In March 2001 the Central Council of Tlingit and Haida Indian Tribes of Alaska passed the resolution Object to Cruise Ship Dumping of Pollutants in Southeast Alaska Waters. The resolution cited a contamination threat to subsistence foods from cruise-ship wastes. The petition asked the federal and state governments to prohibit all discharges within twelve miles of the Alaska shore, require all cruise lines to have discharge monitoring devices, and to prohibit ships caught illegally discharging from entering southeast Alaskan waters.
PLASTICS.
Plastics such as bags, containers, bottle caps, and beverage carriers are dumped daily from oceangoing vessels, commercial and recreational fishing boats, offshore oil and gas platforms, and military ships. Other types of plastic debris—factory wastes, sewer overflows, illegal garbage dumping, and human littering—come from land sources. An estimated two million sea birds and 100,000 marine animals die each year as a result of ingesting or becoming entangled in plastic.
Another concern is commercial fishing nets. Once made of natural materials, these nets are now made mainly of durable, nondegradable plastic. When they are lost or discarded in the water, they pose a floating hazard to seals, dolphins, whales, and diving birds, which can become entangled in the nets. In 1988, thirty-one nations ratified an agreement making it illegal for their ships to dump plastic debris, including fishing nets, into the ocean. As part of that agreement, the United States enacted the Marine Plastics Pollution Research and Control Act (PL 100–220), effective in 1989. Among other regulations, the act imposed a $25,000 fine for each violation.
Plastic pellets are the raw materials that are melted and molded to create plastic products. About sixty billion pounds of resin pellets are manufactured in the United States annually. The two primary ways that these pellets enter water are direct spills during cargo handling operations at ports or spills at sea, and storm-water discharges that carry the pellets from industrial sites. Plastic pellets may persist in the water environment for years, depending on the resin type, the amount and types of pellet additives, and how the pellets react to sunlight, wave action, and weathering. Although pellets have been found in the stomachs of wildlife, primarily seabirds and sea turtles, their effects have not been clearly demonstrated to be harmful.
Since 1991 the Society of Plastics Industries, Inc. (SPI), the major national trade association for manufacturers who make about 75% of the plastic products in the United States, has been working with the EPA to identify and minimize the sources of plastic pellet entry into water. In July 1991 the SPI instituted Operation Clean Sweep, an industry-wide education campaign to encourage members to adopt the SPI 1991 Pellet Retention Environmental Code and the 1992 Processor's Pledge aimed at committing the U.S. plastics industry to total pellet containment. As of 2005 the Operation Clean Sweep mission remained "to help every plastic resin handling operation implement good housekeeping and pellet containment practices to work towards achieving zero pellet loss" (http://www.opcleansweep.org/overview/, 2005).
GHOST FISHING.
Another important problem has been termed "ghost fishing." This is the entrapment of fish and marine mammals by lost or abandoned nets, pots, fishing line, bottles, and other discarded objects. When marine creatures are entangled in old six-pack beverage binders, or caught in abandoned fishing nets, they suffer and may die.
Ocean Dumping
In 1972 Congress enacted the Marine Protection, Research, and Sanctuaries Act (MPRSA; PL 92–532) to prohibit the dumping into the ocean of material that would unreasonably degrade or endanger human health or the marine environment. The MPRSA applies to waters within 200 miles of the U.S. coast and was amended in 1988 to prohibit dumping industrial waste and sewage sludge into the ocean. As a result, ocean dumping today is confined to material dredged from the bottom of water bodies in order to maintain navigation channels and berthing areas. According to information available on the EPA Web site in 2005, several hundred million cubic yards of sediment are dredged from waterways, ports, and harbors each year, and approximately 20% of this material is disposed of in the ocean. The remainder of the sediments are disposed of in inland waters, upland areas, or confined disposal areas adjacent to shorelines, or are used beneficially.
The MPRSA authorizes the EPA to assess civil penalties of up to $50,000 for each violation, as well as criminal penalties (seizure and forfeiture of vessels). For dumping of medical wastes, the Act authorizes civil penalties of up to $125,000 and criminal penalties of up to $250,000 and five years in prison, or both.
Dredging
Every year, millions of tons of materials are dredged from freshwater river channels and harbors, as well as estuarine channels and coastal harbors, to clear or enlarge navigational channels, to maintain ship-berthing areas, to facilitate recreational boating, or for development purposes. Dredged material (spoil) may be clean sand and sediment, or it may contain concentrations of pesticides, metals, and other toxic chemicals, depending on where the dredged material originated. During the dredging process or when the dredged spoil is placed overboard, some pollutants that have settled into the sediment may be released into the water at the disposal site. Dredged spoil disposal is closely regulated by both the U.S. Army Corps of Engineers and the EPA, who require testing of spoil for contaminants prior to disposal.
Disposal of dredged spoil is a difficult problem. Although many environmental groups prefer land-based disposal to overboard disposal (placement of dredged materials in the ocean or other water body at a distance from the dredging location), land-based disposal is frequently not an option. Land adjacent to waterways is usually the most expensive land in the area because of its desirability for development, or it may be wetland and cannot be disturbed or filled.
Land-based disposal sites require large tracts of land where bermed or leveed containment areas can be built to hold the dredged spoil. Berms and levees are raised earthen structures used to form holding areas for dredged spoil. Depending on the composition of the spoil, the dredged material may take ten or more years to "dewater" (dry out) so that the berms can be dismantled and the land used for another purpose, or the containment pond converted to another use, such as fish ponds for aquaculture. Even if the land is available, many communities object to having the disposal area with its eight- to twenty-foot levees, claiming it is unsightly and lowers property values. Transporting dredged spoil (a slurry mud that is about 98% water) any distance to a land-based site, unless it can be pumped to the location, is prohibitively expensive and may require additional dredging to obtain access for the transport barges.
In many cases, ocean- and land-based disposal sites are not economically available to river and estuary sites that require dredging. Two techniques that are being used more often in these areas are artificial containment islands and wetland construction or rehabilitation. Island construction is frequently used where shipping channels need to be maintained through repeated dredging at five- to ten-year intervals, and the "island" site is used over a long time, or when the spoil is badly contaminated with toxic substances. In other cases, clean spoil is used to rebuild eroded islands. When filled and dewatered, island sites may become recreational areas or wildlife refuges, particularly nesting islands for birds. All island sites require extensive construction of costly bulkheads and other containment devices.
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