What is oil spill, different types, causes & effects

Oil spills, not a very common term but a serious form of environmental pollution. While we are trying to explore every kind of environmental issues oil spills is one major area which we should not omit. Thus dealing with what is oil spill, its different types, causes, effects and moreover the worst 10 oil spills that have been happened in the World.

What is Oil Spill?

As the word suggest, it is the release or escape of oil into the sea or any other water body. In other words, oil spills can be defined as contamination of water bodies due to spilling of oil due to negligence of humans or an accident. This term oil spills is generally associated with marine oil spills where the oil is released directly to the deep sea.  The oil spills include any type of crude oil or any type of distilled oil like kerosene, lubricating oil, diesel fuels, gasoline, hydraulic oil and jet fuels. This oil spill can be a few gallons to millions of gallons. The costs incurred in cleaning of these spills are enormous and it can take months and years. The oil spill act was passed in 1990 and further revised in 1994 to prepare and prevent oil spills.


  • Class A oil :
    Class A oil is the most toxic oil. It is light and spreads quite easily. It has a very strong smell. This type of oil soaks into the soil and easily mixes with water. Crude oil, jet fuel and gasoline come under class A oil. This adversely affects the marine life and humans.
  • Class B oil :
    Class B oil are less toxic than compare to class A oil. These are non sticky oils which can cause long term contamination and are highly inflammable. Kerosene, heating oil and low quality crude oil come under this category.
  • Class C oil :
    Class C oil are thick and heavy oil that do not penetrate or dilute into water and soil quickly. They produce a sticky film on the surface and cause severe contamination. Variants of crude oil, bunker B and bunker C oil come under this category.
  • Class D oil :
    Class D oil is considered solid oils. These are the least toxic oils that harden when heated. The cleaning up of this oil is impossible.
  • Non petroleum oil :
    Non petroleum oil is thin type of oil that penetrates into the soil and water easily and cause severe damage. Synthetic oils derived from animal and plant fat comes under this category.
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  1. Natural causes : some of the oil spills occur due to natural causes. Sometimes oil may seep out from the bottom of oceans when sedimentary rocks degradate due natural process at the bottom of the ocean floor.
  2. Human causes : oil spills due to various man made reasons like
    • negligence and lack of awareness
    • lack of proper technology
    • leakage during transportation and storage
    • lack of proper maintenance of oil vessels
    • due to accidents


  • Effects on marine life : oil spills have negative impact on the marine animals. Since most of the oil floats in water, the sunlight absorbing capacity of the water decreases. Thus, the oxygen withholding capacity and the percentage of oxygen in water decreases. This affects the marine animals as there is less oxygen in water. Due to water pollution, immunity of the marine animals reduces leading to its death. The reproductive capacity of the females diminishes due to pollution which will lead to extinction of the species. Marine mammals like whales and dolphins also get affected as the oil clogs their blowholes making it impossible for the animals to breathe. Their ability to communicate also gets affected due to oil spills. Most of the plants get affected due to oil spills and they vanish from the ocean bed. This affects the global food chain.
  • Effect on environment : oil spills is serious environmental pollution. A lot of toxins are flushed into the atmosphere and soil. When oil is spilled, the soil absorbs it. This in turn mixes with the water table below. The natural vegetation, agriculture, plants, shrubs and even trees get affected as they absorb this toxic water from beneath. Thus the whole are become unsuitable due to infertility. The natural habitat of the birds, their nesting and breeding grounds gets disrupted due to oil spills on the ground. This oil can be deadly to the flying birds also. The birds sometimes get coated with oil which makes them vulnerable to hypothermia (fluctuations in body temperature) and reduces the ability to fly. The pray also gets coated with oil which when consumed by the birds causes damage to the internal organs leading to death.
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  1. Gulf war oil spill- 1,360,000 – 1,500,000 tones (8million barrels) in the year 1991.
  2. Ixtoc oil well- 454,000 tones was spilled due to explosion of oil well in the year 1979 in Gulf of Mexico
  3. Atlantic empress- 287,000 tones were spilled when this oil tanker collided with another ship in 1979 in Caribbean Sea.
  4. Fergana valley- 285,000 tones were spilled on land in the year 1992.
  5. Nowruz oil field- 260,000 tones were spilled when a tanker collided in 1983 during first gulf war.
  6. ABT summer- 260,000 tones were spilled due to leakage in the year 1991 in Angolan coast.
  7. Castillo de bellver- 252,000 tones were spilled due to explosion of the oil tanker in 1983 in Cape Town.
  8. Amoco Cadiz- 223,000 tones were spilled when a ship sank in the year 1978 in France.
  9. The haven- 145,000 tones were spilled due to explosion in 1991 in Italy.
  10. The odyssey- 132,000 tones were spilled when an oil tanker split into two in 1988 in Nova Scotia.

Our planet earth has large reserves of oil underneath. These have to be wisely used without wastage and spillage. A lot of permanent damage is caused to the environment and marine life due to negligence and accidents. This can only be prevented by creating awareness among people who work in the industry and use of proper advanced technology.  cleaning up of oil spills is near to impossible and it can take years. Many factors need to be considered like amount of oil spilled, type of water, temperature and depth of water and the type of oil spilled and so on. All these toxins can prove to be fatal. Oil spills occur frequently. As per the reports, eight million barrels are wasted and spilled every year due to negligence and accidents. Majority of the spills occur in water which affects the marine life as a whole. This pollution is life taking and cannot be reversed. Some of the common methods used foe cleaning oil spills are by using biological agents or bioremediation, controlled burning that causes reduction of oil in water, by using dispersants that dilute oil, dredging, skimming and solidifying. Some of the equipments used during the process of cleaning are biological agents, vacuums, sorbets, shovels and booms and skimmers.

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