The oil spill in the Gulf of Mexico During 2010 it is the largest environmental disaster to have occurred in the United States, as a result of the explosion, fire and shipwreck of the semi-submersible platform Deepwater horizon in charge of the company British Petroleum (BP).
The platform extracted oil at a depth of 5,976 m, in the Macondo well, located north of the Gulf of Mexico 75 km off the coast of Louisiana, in the exclusive economic zone of the United States..
The spill lasted for more than 100 continuous days, from April 20, 2010, when the platform explosion occurred, until August 5 of that same year, when the well was finally sealed..
Investigations have revealed that this incident occurred due to decision-making that prioritized speed and cost reduction during the oil extraction process..
It is estimated that almost 5 million barrels were discharged into the waters of the Gulf, with dire effects on wetland ecosystems and marine biodiversity. However, the real effects of this spill have yet to be assessed..
Among the mitigation actions that were taken into account during the spill, and the following days, the direct collection and burning of crude oil, the washing of wetlands and chemical dispersants stand out..
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Investigations carried out after the wreck of the platform reveal a set of wrong actions based on speeding up processes and reducing costs, violating industry guidelines and ignoring safety tests.
At the time of the accident, the Macondo well exploitation program was 43 days late, which translates into an additional $ 21.5 million, nothing more for the rental of the rig. Probably, economic pressures forced a set of wrong decisions that unleashed a great catastrophe.
According to a report on the causes of the incident, there were errors in the process and in the quality of the cementing at the bottom of the well, which allowed the hydrocarbons to enter the production pipeline. In addition, there were failures in the fire control system, which should have prevented the gas from igniting..
The explosion and subsequent fire on the platform caused the death of 11 people belonging to the technical staff that operated on the platform. Deepwater horizon.
In its totality, the oil spill was estimated at 4.9 million barrels, discharged at a rate of 56 thousand barrels per day, which reached an area of 86,500 to 180,000 kmtwo.
According to the US Federal Fish and Wildlife Service, the states most affected by the oil spill were Florida, Alabama, Louisiana, Texas and Mississippi.
The impact on Mexican coasts was also reported.
The effect of the oil spill from the Macondo well on the vegetation of the wetlands includes both acute short-term damage and chronic damage that is evident in a longer period of time..
The main acute damage in marshes occurs when plants suffocate due to anoxic conditions created by multiple coatings of oil. With the death of the vegetation, its function in containing the substrate ceases, the soil collapses, floods and there is no replacement of plants..
During the month of November 2010, the Federal Fish and Wildlife Service of the United States identified 1,500 kilometers of coastline with the presence of crude oil. Ecosystems of marshes, mangroves and beaches were affected.
A 2012 study on the composition of the microbial community of wetlands impacted by the spill showed a decrease in the population size of anaerobic aromatic degraders, sulfate reducers, methanogens, nitrate to ammonia reducers and denitrifiers..
In this sense, the results of the research indicate that the effects of the spill influenced the structure of the populations involved in the biogeochemical cycles of nutrients. These alterations show a possible deterioration in the environmental benefits of the wetlands affected by the spill..
The birds of the Gulf of Mexico were affected by the oil spill in the Macondo well mainly due to loss of buoyancy and the properties of their plumage as thermal insulation in cases where their bodies were covered with oil, and due to ingestion of crude through food.
Investigations by the US Fish and Wildlife Service in mid-November 2010 counted 7,835 birds affected by the oil spill..
Of the total, 2,888 specimens were covered in oil, of which 66% were dead, 4,014 showed evidence of internal contamination due to ingestion of crude oil, of which 77% did not survive, and 933 individuals died, whose level of contamination was unknown..
These values are an underestimate of the real numbers, as they do not include migratory bird data.
Mammals affected by the spill include both those that inhabit the marine environment and those that are distributed in terrestrial habitats influenced by the spill, with marine mammals being the most vulnerable.
Marine mammals such as dolphins and sperm whales were affected due to direct contact with crude oil that cause skin irritations and infections, poisoning from ingestion of contaminated prey and inhalation of petroleum-derived gases..
The US Federal Fish and Wildlife Service, as of early November 2010, had identified 9 live mammals, of which 2 were covered in oil. Of these only 2 were returned to freedom. 100 dead individuals were also captured, of which 4 were covered in crude oil..
Among the affected reptiles, six species of sea turtles stand out. Of 535 turtles captured alive, 85% were covered in oil, of these 74% were cared for and released alive. Of 609 individuals collected dead, 3% were covered in crude oil, 52% had crude oil remains, and 45% had no obvious traces of external contamination..
Corals in the Gulf were also affected by the oil spill. Exposure to oil and chemical dispersants caused the death of coral colonies and in other cases caused damage and physiological stress marks..
The fish affected in the spill are mainly the pale sturgeon (endangered species) and the gulf sturgeon (threatened species). Damage can occur from ingesting crude directly or through contaminated plankton. Crude oil is also known to alter the heart development of these animals.
Contact with oil can contaminate plankton, which forms the basis of the food chain of coastal wetland and marine ecosystems.
In a first phase, efforts focused on capturing oil in open waters with the use of barriers, with the aim of preventing it from reaching the coasts, from where it is much more difficult to extract..
Through this method, 1.4 million barrels of liquid waste and 92 tons of solid waste were collected..
This method consists of setting fire to masses of crude oil accumulated on the surface. It is considered one of the most effective techniques when removing the most toxic compounds from oil, such as aromatic compounds..
During the days after the spill, 411 oil burns were carried out on the surface of the water, thereby controlling 5% of the oil spilled..
Chemical dispersants are a mixture of surfactants, solvents and other chemicals, which, like soap, act by breaking the oil into small droplets, which are then distributed in the water column and can be degraded by microorganisms..
It is estimated that 8% of the spilled oil was dispersed using this method.
BP applied amounts of chemical dispersants that exceeded those allowed. In addition, they applied it both on the ocean surface and at the underwater level, even though the latter procedure was in a phase of experimental tests to evaluate its collateral effects..
Chemical dispersants have a harmful effect on marine life, so many authors think that in this case “the remedy may be worse than the disease".
On the one hand, it consumes oxygen in large quantities causing large anoxic areas, which cause the death of phytoplankton, affecting the base of the trophic chain. On the other hand, it is known that the molecules of the chemical dispersant are accumulated in the tissues of living organisms..
The long-term effects of the use of chemical dispersants to mitigate the effects of the Gulf of Mexico spill on marine life have yet to be assessed..
During the days of the spill, actions were focused on gathering information on the presence of oil on the coast. While the spill continued, collecting oil and cleaning wetlands was considered a secondary task due to the risk of recontamination..
Therefore, for more than 100 days, only large volumes of crude oil were removed from beaches and salt marshes, but not extensively cleaned. Thus, wetland cleanup was taken as a priority once the well was sealed and the spill stopped..
The main methods used to clean marshes and mangroves were mechanical harvesting and washing, given the environmental sensitivity of these ecosystems..
This technique included the manual collection of crude oil remains. It can be done with the help of shovels, rakes, vacuum cleaners and other equipment. It was used mainly on sandy beaches, from where 1,507 tons of oil were removed..
This technique was used to remove the remains of crude oil from the swamps. It consists of doing a low pressure wash to push the oil to areas where it can be aspirated.
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