What is being done to respond to the spill?
Presently, two simultaneous response methods are being used:
The first response method is to stop the release of oil. This is being attempted through the use of remotely operated vehicles (ROV) to activate anti-blowout devices at the wellhead. If this is not successful, other strategies are being prepared, including capturing the oil directly above the leaking pipeline using a large containment chamber and pumping the oil to barges on the surface. A final, permanent solution that is in progress, but will take several months to complete, is to drill relief wells in the same oil reservoir to relieve pressure.
The second response method being used is to remove or disperse the oil that has already been released to prevent it from reaching shore. There are many potential methods available, including in situ burning, sorbents, herding, chemically dispersing, booming off sensitive areas, and mechanical removal. In situ burning, dispersants and booms are currently being used as the primary removal tools.
What is in situ burning?
An in situ burn is the burning of oil at or near the site of the spill. This is done by containing large portions of the spill and igniting them. This is effective at removing large quantities of oil from the water column, but there are risks. These burns create a lot of smoke and residual product, and environmental trade-off should be examined.
What are Dispersants?
Dispersants are a chemical used to break up oil spills and disperse them into the water column. While this is effective at breaking up surface slicks to prevent oiling of birds and beaches, it transfers the oil into the water column and can increase the risk for underwater species.
Dispersants are most effective when the following conditions exist:
- Deep water: the deeper the water, the more the dispersed oil can dilute, the less dangerous it becomes.
- Wind & Waves: These chemicals need to mix with the oil on the surface. This is done through waves and winds creating turbulence.
- Oil Type: Oils that are more viscous are the ideal candidates for dispersants, as they have a tendency to stick together on the surface. Crude oils (what is being spilled from the well) and fuel oils for ships are dispersant candidates.
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What are booms?
Since oil floats on the surface, it can be directed through the use of booms. Booms are long floating barriers used to contain oil to a certain area, or to protect areas from spreading oil (beaches, wildlife reserves, water intakes, etc.). These booms are effective in calm waters with little disturbance on the surface. When employed with skimmers, they can be used to contain and remove oil from the water surface.
In what conditions can in situ burning be used as a response tactic?
In situ burning can be a very effective cleanup method. Under prime conditions removal efficiencies can exceed 90%, however, this method has many limitations including:
- Minimum thickness of oil required (1 mm for volatile, fresh crude, 10 mm for residual fuel oils)
- Oil must be contained to prevent spreading of burning oil
- The wind must not exceed 20 knots and seas should not exceed 2-3 feet
- There must be good visibility so that the burn can be monitored from aircraf
General Shoreline cleanup strategy:
Various shoreline cleanup methods are discussed below. Alternative methods are chosen depending on the shoreline type and amount of oil.
Beach washing and cleaning:
Sandy beach cleanup is relatively easy to cleanup. Beach cleanup typically involves physically removing oil and/or oiled sand or sediment. Oiled rocky beaches are more difficult to cleanup because physical removal is typically not feasible. Washing rocks using high-pressure sprayers and surfactants will remove oil from the rocky shorelines.
Vegetation clearing and in-situ burning:
It is difficult to remove oil from vegetation within salt marshes. Two commonly used methods are vegetation clearing and in situ burning. When oil has entered a salt marsh and coats the vegetation clearing the impacted vegetation will be the most feasible solution. The vegetation will grow back within a few seasons because the root structure remains unharmed. In situ burning relies on the same concept as vegetation clearing, protecting the root structure. If there is a thick enough layer of oil in the marsh it can be burned as a cleanup method.
Under certain conditions, oil can degrade naturally. Since oil is an organic substance, some bacteria are able to use oil as food source, resulting in a significant degradation of oil in the environment. This can be a long process that may take many years to complete, and requires a great deal of monitoring, but it generally is less destructive to sensitive environments than many other forms of remediation in small spill events. Occasionally, natural degradation of oil can be sped up through the addition of nutrients in a process called enhanced bioremediation. Supplementing nutrients increases the amount of bacteria present, and thus increases the overall degradation rate of the oil. This may reduce the time required for full remediation. Unfortunately, successful bioremediation of oil in onshore environments is difficult and requires extensive monitoring, and success is not guaranteed.
Oil-Mineral Aggregate (OMA)
One method available to responders is the injection of fine
mineral particles , usually clay, into the oil plume. The
particles attach to the bulk oil, increasing its density.
When enough particles have been added, the density becomes
greater than seawater, forcing the oil to sink to the bottom
of the ocean, rather than float to the surface. For more
information, consult this report:
What endangered species are at risk from this spill?
The inshore Gulf of Mexico is home to many threatened and endangered species, including the Gulf Sturgeon, Smalltooth Sawfish, Dusky, Night and Tiger Sharks, Nassau and Warsaw Grouper, as well as five species of sea turtles (Kemp’s Ridley, Hawksbill, Green, Loggerhead and Leatherback). Although many marine mammals frequent the Gulf of Mexico, they typically remain offshore in deeper waters.
How will this affect the many bird species that inhabit the Gulf of Mexico?
The Gulf of Mexico is home to many nesting and sea birds, many of whom can potentially be affected by the Mississippi canyon spill, including the brown pelican, which was only removed from the endangered species list in 2009. Other species that may be potentially affected include beach nesting terns and gulls (Caspian Tern, Royal Tern, Sandwich Tern, Least Tern, Laughing Gull, Black Skimmer, Beach nesting shorebirds, American Oystercatcher, Wilson's Plover, Kentish (Snowy) Plover, Reddish Egret, and large wading birds (Roseate Spoonbill, Ibises, Herons, Egrets).
For more information about the potential effects of this spill on birds in the gulf, visit:
What effects would landfall of the spill have?
The Gulf coast contains approximately 60% of the marsh land in the U.S., and is important habitat for numerous species. This marshland is already threatened by subsidence, oil and gas exploration related damage (i.e., trenching for pipelines), and wetlands loss due to development. Landfall of the spill will result in oiling of coastal marshlands, potentially resulting in significant effects on flora and fauna.
How will this affect the commercial fishing industry?
The extent to which this affects the commercial fisheries will depend upon the amount of oil spilled and efficacy of cleanup efforts. The Deepwater Horizon spill will likely affect the Menhaden fishery, where the Gulf of Mexico provides up to one-third of the nations Menhaden, which is a common source of fish oil and fish meal. The Gulf of Mexico is also important spawning site for Atlantic Bluefin Tuna, whose larvae spend most of their time at the surface, and are susceptible to oil slicks. The affect of the spill on the commercial fishing industry has yet to be determined, however, the large extent of the spill is likely to significantly restrict fishing activities in the area.
How important is the Gulf of Mexico to the U.S. shellfish industry?
The U.S. obtains approximately 70% of its shrimp and oysters from Gulf of Mexico waters. If these species are exposed to oil, they may become tainted and may curtail the harvest, significantly impacting the U.S. supply.
How has this affected Gulf of Mexico Oil Production?
As of April 30, current oil production in the Gulf of Mexico has not been affected. However, President Obama’s Press Secretary David Axlerod announced that there will be no more drilling on new leases until the cause of the blowout has been determined. It should be noted, however, new drilling on currently owned leases has not been affected.
What is the Oil Spill Liability Trust Fund (OSLTF)?
A fund established by the Oil Pollution Act of 1990 in order to fund response, restoration, and research and development related to oil spills. The responsible party (RP) of an oil spill is responsible for paying up to $75 million of the response and restoration costs, when this amount is exceeded funding from the OSLTF is used. The OSLTF is funded by an 8 cent per barrel tax on imported or processed oil in the US.