Tuesday, 7 September 2021

Divers looking for source of oil spill find broken pipelines in the Gulf of Mexico.

Divers searching for the source of an oil slick that appeared on the Gulf of Mexico in the wake of Hurricane Ida have found three broken pipelines on the seabed to the south of the city of New Orleans. The oil was first observed on Wednesday 1 September by an aerial survey caried out by the National Oceanic and Atmospheric Administration, with additional footage being taken from a helicopter chartered by the Associated Press the next day. This prompted a clean-up operation by Talos Energy, who previously leased  Bay Marchand, Block 5, the area where the slick appeared, and Clean Gulf Associatesa nonprofit oil-spill response cooperative hired by Talos to help with the operation. Now divers from Clean Gulf have identified a broken 30 cm diameter pipeline with oil leaking from it, plus two further broken 10 cm pipelines, which are not currently leaking, but which may have contributed to the spill. Talos Energy do not believe that these pipelines were part of their operation, as their records show all seabed pipelines operated by the company were removed when their activities ceased in 2017. If this is correct, then it is unclear who the pipelines belonged to.

Satellite image showing an oil slick to the south of Port Fourchon, Louisiana, on 2 September 2021. Maxar Technologies/AP.

Hurricane Ida made landfall in Louisiana on Sunday 29 August 2021, and bringing with it high winds and flooding which led to more than 50 deaths on the eastern United States.  However, the fact that the death toll was not much higher has been hailed as a vindication of the billions of dollars that have been invested in the levee system protecting the city of New Orleans following the catastrophic damage caused by Hurricane Katrina sixteen years ago. The city, which was directly in the path of the storm, suffered wind damage as it was battered by 240 km per hour winds, but only a limited amount of flooding. A plan to evacuate large parts of New Orleans in the event of it being hit by another major hurricane was not put into place because of the rapidity with which the storm formed, developing over the Caribbean Sea only four days before making landfall as the fifth largest storm ever to hit the US coast.

The storm also caused flooding at the Phillips 66 Alliance Refinery, which is beside the Mississippi River to the south of New Orleans, where a sheen has subsequently been observed on the water, implying that some leaking has occurred here to, although the refinery was shut down ahead of the storm, which should have prevented any major incident.

Tropical storms, known as hurricanes in the Atlantic and eastern Pacific, are caused by solar energy heating the air above the oceans, which causes the air to rise leading to an inrush of air. If this happens over a large enough area the inrushing air will start to circulate, as the rotation of the Earth causes the winds closer to the equator to move eastwards compared to those further away (the Coriolis Effect). This leads to tropical storms rotating clockwise in the southern hemisphere and anticlockwise in the northern hemisphere. These storms tend to grow in strength as they move across the ocean and lose it as they pass over land (this is not completely true: many tropical storms peter out without reaching land due to wider atmospheric patterns), since the land tends to absorb solar energy while the sea reflects it.

The formation of a tropical cyclone. Natural Disaster Management.

Despite the obvious danger of winds of this speed, which can physically blow people, and other large objects, away as well as damaging buildings and uprooting trees, the real danger from these storms comes from the flooding they bring. Each drop millibar drop in air-pressure leads to an approximate 1 cm rise in sea level, with big tropical storms capable of causing a storm surge of several meters. This is always accompanied by heavy rainfall, since warm air over the ocean leads to evaporation of sea water, which is then carried with the storm. These combined often lead to catastrophic flooding in areas hit by tropical storms.

The formation and impact of a storm surge. eSchoolToday.

Many officials in the US, including President Joe Biden, have linked Hurricane Ida directly to global warming, noting that the average storm hitting the US today does seven times as much damage as in the 1970s, that 'hundred year' storms now happen several times a decade, and that states formerly to the north of the hurricane zone are now regularly hit by these storms.

Oil spills are potentially harmful to marine life in a variety of ways. Most obviously it can coat the outside of organisms, causing damage to external structures such as the feathers of Birds and fur of Mammals, as well as smothering many marine invertebrates and plants. It also contains a variety of chemicals which can be directly toxic upset the hormonal balance of many animals. Oil also impedes the feeding of marine organisms, coating both food and feeding organs, but provides an excellent food source for Bacteria, which can lead to Eutrophication events - dramatic increases in Bacteria numbers, which then use all the oxygen in the water, leading other organisms to asphyxiate.

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