Oil in the Ocean: Spills, Natural Seepage and Ships

Home | Category: Ocean Environmental Issues


massive oil platform off Brazil

Oil spills can cause big maritime disasters but the effects are often relatively temporary. The oceans are big enough so that most pollution and oil spills are eventually dispersed. Oil platforms some distance from shore offer a refuge for many marine organisms. Platforms and sunken ships create artificial reefs.

“Petroleum input” is the term used to describe the leakage of oil into the sea whether from oil spills, leaky ships or natural seepage, The total global petroleum input is thought to be about 380 million gallons a year. Much of the input off the United States comes from natural seeps. Approximately 20,000 oil spills are reported in the U.S. every year. Most are small and don’t draw much attention. Only a small number require more than $1 million to clean up.

“The oil industry has vastly improved it record avoiding oil spills. Matt Ridley wrote in The Times: The number and collective size of oil spills (over 7,000 tonnes) has declined in each of the last four decades, from 25 large spills and over 250,000 tonnes a year in 1970-1979 to three spills and about 20,000 tonnes a year in 2000-2009: that is a drop of more than 90 percent.”[Source: Times of London]

“The severity of an oil spill is often determined based on the volume of oil released into the environment. But in terms of the damage caused a lot of factors come into play: distance of the spill from the coast; ocean currents; wind directions; weather; chemistry of the oil; water temperatures and ocean hydrodynamics. Even though the Exxon Valdez is ranked the 37th worst oil spill in terms of oil released it was very damaging to the environment because the spill was close to shore and the area was home to lot of aquatic life. Another large spill, the break up of the Braer off the coast of Scotland in 1993, was twice as large, releasing 25 million gallons crude, but had relatively little known impact on the sea because the oil dispersed quickly and the oil itself — Norwegian light crude — was very light and not very greasy.

Ann Hayward-Walker, who worked on the Exxon Valdez incident, told Times of London: “All oil spills are emotional events” and said the response is often dictated as much by public and media calls for actions and politics rather than science and rational thought. She pointed out that when there is a forest fire firefighters are not distracted by concerns over how the problem was caused, who caused it and whether clean up efforts were causing more damage than the incident itself.

Impact of Oil on Marine Life

20120517-Oil-spill.jpg Oil spills are harmful to marine birds and mammals as well as fish and shellfish. Oil destroys the insulating ability of fur-bearing mammals, such as sea otters, and the water repellency of a bird's feathers, thus exposing these creatures to the harsh elements. Without the ability to repel water and insulate from the cold water, birds and mammals will die from hypothermia. [Source: NOAA]

Juvenile sea turtles can also become trapped in oil and mistake it for food. Dolphins and whales can inhale oil, which can affect lungs, immune function and reproduction. Many birds and animals also ingest oil when they try to clean themselves, which can poison them.

Fish, shellfish, and corals may not be exposed immediately, but can come into contact with oil if it is mixed into the water column — shellfish can also be exposed in the intertidal zone. When exposed to oil, adult fish may experience reduced growth, enlarged livers, changes in heart and respiration rates, fin erosion, and reproduction impairment. Fish eggs and larvae can be especially sensitive to lethal and sublethal impacts. Even when lethal impacts are not observed, oil can make fish and shellfish unsafe for humans to eat.

Following an oil spill, there are specialists and veterinarians to deal with oiled wildlife. These experts are trained on how to clean oil from animals, rehabilitate them, and return them to the environment.

Oil Seep

An oil seep is a natural leak of crude oil and gas that migrates up through the seafloor and ocean depths. Naturally occurring oil seeps from the seafloor are the largest source of oil entering the world ocean. In fact, they account for nearly half of the oil released into the ocean environment every year. [Source: NOAA]

Seeps occur when crude oil leaks from fractures in the seafloor or rises up through seafloor sediments, in much the same way that a freshwater spring brings water to the surface. NOAA's Office of Response and Restoration (OR&R) is interested in oil seeps because they are predictable places to observe oil behavior. In Santa Barbara, California, where many natural seeps are found, OR&R trains aerial observers, calibrates trajectory models, and performs other tasks to determine how weather, wind, tides, and currents affect oil movement.

oil seep off California

When an oil spill occurs in an area with many naturally occurring seeps, responders may have a hard time telling the difference between spilled oil and seep oil. The difference is important because the environmental impacts of oil are determined not only by the amount of oil released into the environment, but also by the type of oil and the speed at which it will disperse. Natural seeps release oil slowly over time, allowing ecosystems to adapt, whereas oil spills from human activities like commercial oil transport can quickly release oil in quantities that overwhelm an ecosystem.

Nonetheless, all oil seeps impact the marine environment. Oil can be toxic to sea life like fish, sea stars, shrimp, and seabirds, with their impacts largely concentrated in the immediate area around a seep. OR&R tracks naturally occurring oil seeps, helps distinguish oil seeps from production-platform leaks and other spills, and works with partners like the U.S. Coast Guard and the U.S. Fish and Wildlife Service to enhance techniques like oil fingerprinting to determine where oil originates.

Intentional Dumping of Massive Amounts of Oil by Ships

According to an investigation by the Washington-D.C.-based Outlaw Ocean Project, a nonprofit journalism organization, every three years, ships intentionally dump more oil than the Exxon Valdez and BP spills combined. Ian Urbina wrote: On August 2013, Chris Keays, a newly hired engineer on an American cruise ship, the Caribbean Princess, knew immediately that something was amiss in the massive vessel’s engine room. The Scotsman was a low-level engineer who had just graduated from nautical school and had signed up for what he believed was his dream job aboard the 952-foot ocean liner, one of the largest passenger ships on the planet. The famed ship was a floating village, with a mini golf course, a casino, an outdoor movie theater and 19 decks, with room for more than 3,000 passengers and roughly 1,000 crew members. [Source: Ian Urbina, The Outlaw Ocean Project, Yahoo News, November 1, 2022]

Venturing into an unfamiliar section where he did not typically work, Keays saw an illegal device known in the industry as a “magic pipe.” From his marine studies in Glasgow, Scotland, Keays knew exactly what he was looking at. Several feet long, the pipe stretched from a nozzle on a carbon filter pump to a water tank. Its magic trick? Making the ship’s used oil and other nasty liquids disappear. Rather than storing the highly toxic effluent and unloading it at port, as the ship was legally required to do, the pipe was secretly flushing the waste into the ocean, saving the ship’s owner, Carnival Corporation, millions of dollars in disposal fees and port delays. Keays used his cellphone to take shaky video and pictures of the pipe, as well as photographs of the engine-room computer screen that showed how discharges were being manipulated.

Cruise liners, like most large ships, burn massive amounts of the dirtiest fuel on the market. Before it is used, the fuel is filtered and spun to remove water, debris and chemical impurities, a process that produces what is called engine sludge. Disposing of this especially toxic waste is costly. Cruise liners also produce millions of gallons of oily water. This is the runoff of lubricants and leaks that drip from a ship’s many diesel generators, air compressors, main propulsion engines and other machines and that drain into the ship’s bilge tanks. Other liquid wastes accumulate too. “Black water” refers to sewage from hundreds of toilets flushing day in and day out. “Gray water” comes from washing dishes and clothing for the thousands of passengers aboard or from the slimy food scraps and grease from the ship’s galleys and restaurants. Some of these liquids can be released into the ocean after light treatment, but ship engineers are responsible for ensuring that none of the nastiest fluids get discharged. Sometimes, though, these engineers and their companies resort to magic pipes to make those fluids disappear.

In subsequent court papers, Carnival called the Caribbean Princess an isolated case. But oil logs from the company’s other ships, also disclosed in court records, indicated that oil dumping was a widespread practice and that on occasion, engineers on other Carnival ships tricked the monitoring equipment by pulling in the same volume of saltwater to replace the liquids they dumped.

On the Caribbean Princess, the company had installed three separate machines to monitor and collect waste oil, well beyond what was required by law. Carnival often pointed to the additional machines as proof of its commitment to environmental stewardship. Meanwhile, onboard engineers had devised systems to bypass each of the three monitors. After discovering these ruses, federal prosecutors wrote that Carnival, whose income in 2016 was roughly $2.7 billion, had a “high consciousness of guilt.” In 2016, a federal judge levied a $40 million fine against the company, the largest penalty of its type in nautical history.

Oil Spill Trajectories

During the threat of an oil spill, responders need to know where that spilled oil will go in order to protect shorelines with containment boom, stage cleanup equipment, or close areas for fishing and boating. In order to answer these questions, NOAA oceanographers use specialized computer models to predict the movement of spilled oil on the water surface. They predict where the oil is most likely to go and how soon it may arrive there. During a major spill response, trajectory maps are created to show predictions for the path of spilled oil. [Source: NOAA]

Trajectory maps are produced using a NOAA-developed computer model called GNOME (General NOAA Operational Modeling Environment), which helps to predict the movement of oil. GNOME can forecast the effects that currents, winds, and other physical processes have on the movement of oil in the ocean. During an oil spill, this model is updated daily based on field observations, aerial surveys, and new forecasts for ocean currents and winds.

In addition to showing oiled locations and potential beached oil on a trajectory map, oceanographers will also include an uncertainty boundary on the map to indicate other locations where oil potentially could be located. This uncertainty boundary is necessary to account for differences in models as well as changes in currents and winds.

Cleaning Up Oil Spills

Booms are employed to contain oil and protect beaches, shores and wetlands. Skimmers skim oil off the surface. They are slow, don’t work well in large waves, and have little impact on large spills. Dispersants — which break up the oil and make it easier for natural bacteria in the sea to consume it “are the main chemical weapon. They are usually sprayed from planes which can quickly get the oil spill and cover a large area. There have been many erroneous reports of dispersant causing everything from bleeding rectums and blue lips to spontaneous combustion. [Source: The New Yorker]

A massive oil spill can really muck up a coastline, as scientists learned during EXXON Valdez oil spill in remote Prince William Sound, Alaska, in March 1989. In the wake of that disaster — one of the worst U.S. spills in history — responders took shovels and hoses in hand. Since that time, many new techniques have been developed that are now used routinely in coastal cleanups. NOAA experts help to evaluate trade-offs and best practices in oil spill response tools, techniques, and technologies. Much has been learned about the tricky business of removing oil from open water since the April 2010 BP Deepwater Horizon incident in the Gulf of Mexico. [Source: NOAA]

The following are different tools used for shoreline spill cleanup: 1) Shoreline Flushing/Washing: Water hoses can rinse oil from the shoreline into the water, where it can be more easily collected. 2) Booms: Long, floating, interconnected barriers are used to minimize the spread of spilled oil. 3) Vacuums: Industrial-sized vacuum trucks can suction oil from the shoreline or on the water surface. 4) Sorbents: Specialized absorbent materials act like a sponge to pick up oil but not water. 5) Shoreline Cleaners & Biodegradation Agents: Chemical cleaners that act like soaps may be used to remove oil, but require special permission. Nutrients may be added to help microbes break down oil. 6) Burning: Also referred to as "in situ burning," freshly spilled oil can be set on fire, usually when it's floating on the water surface and sometimes on oiled marsh vegetation, in order to effectively remove it. 7) Manual Removal: Cleanup crews using shovels or other hand tools can pick up oil from the shoreline. This method is used especially when heavy machinery cannot reach an oiled shore. 8) Mechanical Removal: When there is access, heavy machinery, such as backhoes or front-end loaders, may be used. Responding to Oil Spills at Sea The following graphic describes a few methods used to respond to oil spills that occur in the open ocean:

1) Dispersion: Chemical dispersion is achieved by applying chemicals designed to remove oil from the water surface by breaking the oil into small droplets. 2) Burning: Also referred to as "in situ burning," this is the method of setting fire to freshly spilled oil, usually while still floating on the water surface. 3) Booms: Booms are long, floating barriers used to contain or prevent the spread of spilled oil) 4) Skimming: Skimming is achieved with boats equipped with a floating skimmer designed to remove thin layers of oil from the surface, often with the help of booms.

Lightering is the process of removing oil or other hazardous chemicals from a compromised vessel to another vessel to prevent oil from spilling into the surrounding waters. Lightering is not possible in all oil spill scenarios. It depends on many factors including the type of oil that is spilled. As time passes, the oil can become more viscous, or thicker, and therefore more difficult to pump. This can, in turn, make lightering difficult, if not impossible. While there are benefits to removing oil in this way, there can also be accidents and spills that result from lightering. Lightering is also used to transfer cargo between vessels of different sizes like a barge and a bulker or oil tanker to reduce the vessel's draft in order to enter port facilities.

Impact of Cleaning Up Oil Spills on Sea Life

The primary dispersant used in the BP Gulf oil spill was Corexit 9500, whose seven main ingredients are found in things like headache medicines, ice cream bars and hair conditioners. Sorbitan monooleate, for example, is an ingredient in shampoos and juices, Hydrotreated light-petroleum is used in air fresheners. Studies in which marine animals are exposed to chemicals for 96 hour to see how they react show dipserants are far less toxic than oil. [Source: The New Yorker]

Impact of Deepwater Horizon spill in 2010

After the oil spill in the Gulf of Mexico in 2010 the government tested dozens of samples of flesh from fish and shrimp caught in the region. The tests begin with a sniff — trained experts smell the flesh, testing for crude or the Windex-like odor of chemical dispersants. Then, the samples are tested chemically for oil; there is no chemical test for dispersants. Of the 3,500-plus samples taken during the spill, officials say none contained enough oil or dispersant to be harmful to people. [Source: David A. Fahrenthold and Juliet Eilperin, The Washington Post, August 16, 2010]

Experts say fish and shrimp don't tend to absorb dispersants and that their bodies tend to break down the toxic components of oil. The chief worry about oil-tainted food is not that it will kill unsuspecting diners. Peter Kramer of the World Wide Fund for Nature told the Washington Post even if such food wound up on a plate, it would smell so oily that diners probably wouldn't eat it. "If, however, you manage to choke it down, then the most common reaction would be a nausea or vomiting reaction."

Investigating Underwater Oil Spills

Marla Valentine, an ecologist at Oceana, an international NGO dedicated to ocean conservation, has used remote-controlled underwater drones to investigate underwater oil damage such as that that occurred after the BP spill in 2010. The New Yorker reported: Valentine ordered the probe down into the midnight zone. The framework entered the water, and feedback on one of the monitors showed the temperature dropping. The readings were normal until eleven hundred meters, when the oxygen levels dipped sharply. “This is a pretty clear oxygen anomaly here,” Valentine said. The probe fluoresced chemicals in the water, revealing the presence of hydrocarbon molecules. It appeared that the team had found a plume. [Source: The New Yorker, May 14, 2011]

“What we’ve noticed is that much of the hydrocarbons that emanated from the BP leak ended up in the thousand-to-twelve-hundred-meter water depth,” Valentine told me. He looked at the anomaly again. “This is very typical for dissolved hydrocarbons,” he said. “Not typical for the ocean.”

When the probe was back on deck, the scientists drew water from the cannisters with large plastic syringes. The word “plume” was scientifically accurate, but the amounts of hydrocarbons in the samples were invisibly minute. In the syringes, the water was frigid and crystal clear.

Research in the Gulf has in many ways been encouraging. At the shoreline, pockets of oil will certainly linger. Although certain species may be at severe risk from the remaining oil, many others, such as sea turtles, do not seem to be under great threat, and the marsh as a whole does not appear to be ecologically devastated. All told, the spill killed fifty-six hundred birds, a dismaying number, but a small fraction of the quarter million that died in the Exxon Valdez spill. Oysters have suffered gravely, though this appears to be from the

Potential impact of an oil spill on the Sargassum Sea ecosystem

Letting Nature Take Care of Oil Spills

Often the best course of action is to do nothing and let nature takes its course.Matt Ridely wrote in The Times: “After most big oil spills, scientists are pleasantly surprised by how quickly the oil disappears and the marine life reappears. This is true even in Alaska, where the sheltered waters, low temperatures and abundant wildlife conspired to make the slick damaging and persistent. The National Oceanic and Atmospheric Administration says on its website: What scientists have found is that, despite the gloomy outlook in 1989, the intertidal habitats of Prince William Sound have proved to be surprisingly resilient.' A scientist who led some of the research into the Exxon Valdez says that Thoughts that this is going to kill the Gulf of Mexico are just wild overreactions'. [Source: Matt Ridely, The Times, July 19, 2010]

“When the Braer went aground off Shetland in 1993 and spilled 85,000 tonnes of oil, storms quickly dispersed the oil, so the effect on most of the local wildlife was barely measurable. As one scientific report drily noted, after running through a list of undetected effects on birds, shore life and seabed creatures, five otters were found dead in the oil spill area. However, three of these were killed by vehicles, one was recovered before the oil could have reached it and the cause of mortality of the fifth did not appear to be oil contamination.' (One of the road kills was allegedly caused by a television crew's car.)

This rapid recovery was also a signature of the last big Gulf rig spill, the Ixtoc 1 disaster off Mexico in 1979. Although the number of turtles took decades to recover, much of the rest of the wildlife bounced back fairly rapidly. 'To be honest, considering the magnitude of the spill, we thought the Ixtoc spill was going to have catastrophic effects for decades', Luis Soto of the National Autonomous University of Mexico told a newspaper this year. 'But within a couple of years, almost everything was close to 100 percent normal again.' The warm waters and strong sunshine of the Gulf of Mexico are highly conducive to the chemical decomposition of oil by 'photo-oxidation', and are stuffed full of organisms that actually like to eat the stuff - in moderation.

“Indeed, the sea floor in the Gulf is rich in 'cold seeps' -- communities of tube worms and other organisms that live off oil naturally seeping from beneath the seabed. (The annual flow of oil through such seeps is about half the total spill.) Hundreds of these clusters of clams and tube worms have been found since the 1980s in the deep waters of the Gulf of Mexico, living off the microbes that eat the oil.

Image Sources: U.S. Department of Energy; Wikimedia Commons

Text Sources: New York Times, Washington Post, Los Angeles Times, Times of London, The Guardian, National Geographic, The New Yorker, Time, Newsweek, Reuters, AP, AFP, Wall Street Journal, The Atlantic Monthly, The Economist, Global Viewpoint (Christian Science Monitor), Foreign Policy, U.S. Department of Energy, Wikipedia, BBC, CNN, NBC News, Fox News and various books and other publications.

Last updated February 2023

This site contains copyrighted material the use of which has not always been authorized by the copyright owner. Such material is made available in an effort to advance understanding of country or topic discussed in the article. This constitutes 'fair use' of any such copyrighted material as provided for in section 107 of the US Copyright Law. In accordance with Title 17 U.S.C. Section 107, the material on this site is distributed without profit. If you wish to use copyrighted material from this site for purposes of your own that go beyond 'fair use', you must obtain permission from the copyright owner. If you are the copyright owner and would like this content removed from factsanddetails.com, please contact me.