On September 3, , the ton failed blowout preventer was removed from the well and a replacement blowout preventer was installed. In May , BP admitted they had "discovered things that were broken in the sub-surface" during the "top kill" effort. Oil slicks were reported in March  and August ,   in March  and October ,    and in January The USCG initially said the oil was too dispersed to recover and posed no threat to the coastline,  but later warned BP and Transocean that they might be held financially responsible for cleaning up the new oil.
In January , BP said that they were continuing to investigate possible sources of the oil sheen. Chemical data implied that the substance might be residual oil leaking from the wreckage. If that proves to be the case, the sheen can be expected to eventually disappear. Another possibility is that it is formation oil escaping from the subsurface, using the Macondo well casing as flow conduit, possibly intersecting a naturally occurring fault, and then following that to escape at the surface some distance from the wellhead.
If it proves to be oil from the subsurface, then that could indicate the possibility of an indefinite release of oil. The oil slick was comparable in size to naturally occurring oil seeps and was not large enough to pose an immediate threat to wildlife. The fundamental strategies for addressing the spill were containment, dispersal and removal. In May , a local native set up a network for people to volunteer their assistance in cleaning up beaches.
Boat captains were given the opportunity to offer the use of their boat to help clean and prevent the oil from further spreading. To assist with the efforts the captains had to register their ships with the Vessels of Opportunity, however an issue arose when more boats registered than actually participated in the clean up efforts - only a third of the registered boats.
This coalition gained significant influence in the clean up of the oil spill to try and gain some control over the situation. Booms extend 18—48 inches 0.
9 of the Biggest Oil Spills in History
The Louisiana barrier island plan was developed to construct barrier islands to protect the coast of Louisiana. The plan was criticised for its expense and poor results. For a time, a group called Matter of Trust, citing insufficient availability of manufactured oil absorption booms, campaigned to encourage hair salons, dog groomers and sheep farmers to donate hair, fur and wool clippings, stuffed in pantyhose or tights, to help contain oil near impacted shores, a technique dating back to the Exxon Valdez disaster. The spill was also notable for the volume of Corexit oil dispersant used and for application methods that were "purely experimental.
A analysis conducted by Earthjustice and Toxipedia showed that the dispersant could contain cancer-causing agents, hazardous toxins and endocrine-disrupting chemicals. The dangers are even greater when poured into the source of a spill, because they are picked up by the current and wash through the Gulf.
Repeated or excessive exposure Underwater injection of Corexit into the leak may have created the oil plumes which were discovered below the surface. In late , a study from Georgia Tech and Universidad Autonoma de Aguascalientes in Environmental Pollution journal reported that Corexit used during the BP oil spill had increased the toxicity of the oil by 52 times.
The three basic approaches for removing the oil from the water were: combustion, offshore filtration, and collection for later processing.
According to EPA 's report, the released amount is not enough to pose an added cancer risk to workers and coastal residents, while a second research team concluded that there was only a small added risk. Oil was collected from water by using skimmers. In total 2, various skimmers were used. Many large-scale skimmers exceeded the limit. After the well was captured, the cleanup of shore became the main task of the response works.
Two main types of affected coast were sandy beaches and marshes. On beaches the main techniques were sifting sand, removing tar balls, and digging out tar mats manually or by using mechanical devices. Dispersants are said to facilitate the digestion of the oil by microbes. Mixing dispersants with oil at the wellhead would keep some oil below the surface and in theory, allowing microbes to digest the oil before it reached the surface.
Various risks were identified and evaluated, in particular that an increase in microbial activity might reduce subsea oxygen levels, threatening fish and other animals. Several studies suggest that microbes successfully consumed part of the oil. Valentine, a professor of microbial geochemistry at UC Santa Barbara , said that the capability of microbes to break down the leaked oil had been greatly exaggerated.
Genetically modified Alcanivorax borkumensis was added to the waters to speed digestion. The first video images were released on 12 May, and further video images were released by members of Congress who had been given access to them by BP. Exceptions for these restrictions were granted on a case-by-case basis dependent on safety issues, operational requirements, weather conditions, and traffic volume.
Local and federal authorities citing BP's authority denied access to members of the press attempting to document the spill from the air, from boats, and on the ground, blocking access to areas that were open to the public. In one example, the U. Coast Guard stopped Jean-Michel Cousteau 's boat and allowed it to proceed only after the Coast Guard was assured that no journalists were on board.
The CBS crew was told by the authorities: "this is BP's rules, not ours," when trying to film the area. On 15 April , BP claimed that cleanup along the coast was substantially complete, but the United States Coast Guard responded by stating that a lot of work remained. Using physical barriers such as floating booms, cleanup workers' objective was to keep the oil from spreading any further. They used skimmer boats to remove a majority of the oil and they used sorbents to absorb any remnant of oil like a sponge. Although that method did not remove the oil completely, chemicals called dispersants are used to hasten the oil's degradation to prevent the oil from doing further damage to the marine habitats below the surface water.
The State of Louisiana was funded by BP to do regular testing of fish, shellfish, water, and sand. Initial testing regularly showed detectable levels of dioctyl sodium sulfosuccinate, a chemical used in the clean up. Testing over the past year reported by GulfSource. A study of the effects of the oil spill on bluefin tuna funded by National Oceanic and Atmospheric Administration NOAA , Stanford University , and the Monterey Bay Aquarium and published in the journal Science , found that the toxins from oil spills can cause irregular heartbeats leading to cardiac arrest. Calling the vicinity of the spill "one of the most productive ocean ecosystems in the world", the study found that even at very low concentrations "PAH cardiotoxicity was potentially a common form of injury among a broad range of species in the vicinity of the oil.
The scientists said that their findings would most likely apply to other large predator fish and "even to humans, whose developing hearts are in many ways similar. The oil dispersant Corexit , previously only used as a surface application, was released underwater in unprecedented amounts, with the intent of making it more easily biodegraded by naturally occurring microbes. Thus, oil that would normally rise to the surface of the water was emulsified into tiny droplets and remained suspended in the water and on the sea floor.
Pelican eggs contained "petroleum compounds and Corexit".
Christopher Haney, Harold Geiger, and Jeffrey Short, three researchers with extensive experience in environmental monitoring and post-spill mortality assessments, over one million coastal birds died as a direct result of the Deepwater Horizon spill. These numbers, coupled with the National Audubon Society scientists' observations of bird colonies and bird mortality well after the acute phase, have led scientists to conclude that more than one million birds ultimately succumbed to the lethal effects of the Gulf oil spill. In July , it was reported that the spill was "already having a 'devastating' effect on marine life in the Gulf".
BP officials deny that the disease conditions are related to the spill, saying that dolphin deaths actually began being reported before the BP oil spill. Before the spill there were an average of strandings per year; since the spill the number has jumped to roughly In , tar balls continued to wash up along the Gulf coast     and in , tar balls could still be found in on the Mississippi and Louisiana coasts, along with oil sheens in marshes and signs of severe erosion of coastal islands, brought about by the death of trees and marsh grass from exposure to the oil.
In , researchers found that oil on the bottom of the seafloor did not seem to be degrading,  and observed a phenomenon called a "dirty blizzard": oil in the water column began clumping around suspended sediments, and falling to the ocean floor in an "underwater rain of oily particles. A bluefin tuna study in Science found that oil already broken down by wave action and chemical dispersants was more toxic than fresh oil. On 12 April , a research team reported that 88 percent of about baby or stillborn dolphins within the spill area "had abnormal or under-developed lungs", compared to 15 percent in other areas.
The study was published in the April Diseases of Aquatic Organisms. The study is run by the National Institute of Environmental Health Sciences , and will last at least five years. Mike Robicheux, a Louisiana physician, described the situation as "the biggest public health crisis from a chemical poisoning in the history of this country. Following the 26 May hospitalization of seven fishermen that were working in the cleanup crew, BP requested that the National Institute for Occupational Safety and Health perform a Health Hazard Evaluation.
Tests for chemical exposure in the seven fishermen were negative; NIOSH concluded that the hospitalizations were most likely a result of heat, fatigue, and terpenes that were being used to clean the decks. Review of 10 later hospitalizations found that heat exposure and dehydration were consistent findings but could not establish chemical exposure.
Gulf Oil Spill | Smithsonian Ocean
NIOSH personnel performed air monitoring around cleanup workers at sea, on land, and during the application of Corexit. Air concentrations of volatile organic compounds and PAHs never exceeded permissible exposure levels. A limitation of their methodology was that some VOCs may have already evaporated from the oil before they began their investigation. In their report, they suggest the possibility that respiratory symptoms might have been caused by high levels of ozone or reactive aldehydes in the air, possibly produced from photochemical reactions in the oil.
NIOSH did note that many of the personnel involved were not donning personal protective equipment gloves and impermeable coveralls as they had been instructed to and emphasized that this was important protection against transdermal absorption of chemicals from the oil.
Heat stress was found to be the most pressing safety concern.
Workers reported that they were not allowed to use respirators, and that their jobs were threatened if they did. A survey of the health effects of the spill on cleanup workers reported "eye, nose and throat irritation; respiratory problems; blood in urine, vomit and rectal bleeding; seizures; nausea and violent vomiting episodes that last for hours; skin irritation, burning and lesions; short-term memory loss and confusion; liver and kidney damage; central nervous system effects and nervous system damage; hypertension; and miscarriages".
James Diaz, writing for the American Journal of Disaster Medicine , said these ailments appearing in the Gulf reflected those reported after previous oil spills, like the Exxon Valdez. Diaz warned that "chronic adverse health effects, including cancers, liver and kidney disease, mental health disorders, birth defects and developmental disorders should be anticipated among sensitive populations and those most heavily exposed". Diaz also believes neurological disorders should be expected.
Two years after the spill, a study initiated by the National Institute for Occupational Safety and Health found biomarkers matching the oil from the spill in the bodies of cleanup workers. These studies also showed that the bodies of former spill cleanup workers carry biomarkers of "many chemicals contained in the oil". A study that investigated the health effects among children in Louisiana and Florida living less than 10 miles from the coast found that more than a third of the parents reported physical or mental health symptoms among their children.
The parents reported "unexplained symptoms among their children, including bleeding ears, nose bleeds, and the early start of menstruation among girls," according to David Abramson, director of Columbia University's National Center for Disaster Preparedness. Women who suffered a high degree of economic disruption as a result of spill were significantly more likely to report wheezing; headaches; watery, burning, itchy eyes and stuffy, itchy, runny nose.