Unforgettable oil spills
The term “oil spill” does not simply mean the presence of hydrocarbons in the marine environment. It refers to a violent spillage concentrated in a specific area, surpassing the natural assimilation capacities of the surrounding environment. Like other phenomena, oil spills have their world records. Accidents involving oil tankers rank top in number, but not in quantity, where they come after acts of war and eruptions on offshore wells.
It is not however necessary for a spill to be record-breaking in terms of volume to mark history. For instance, the Exxon Valdez oil spill in Alaska, which attracted considerable media coverage, is today by far the most expensive spill in history, with some 2.5 billion Dollars spent on clean-up and compensation of victims, plus a fine of 4 billion Dollars which the Exxon group appealed.
Symbolic images of the Amoco Cadiz oil spill (Brittany, France)
The 20 unforgettable oil spills (estimations)
Sources: produced using data from Cedre, Cutter Information Corp., and the Institut Français du Pétrole
However the Exxon Valdez oil spill “only” involved 40,000 tonnes of crude oil. More recently, with a 20,000 tonne spill of heavy fuel oil, the Erika disaster provoked reactions from the general public similar to those caused 21 years earlier by the 227,000 tonnes of crude oil spilled by the Amoco Cadiz. Three years later, the 64,000 tonnes of heavy fuel oil spilled by the Prestige off the coast of Galicia hit some of the areas previously affected by the Erika and brought post-Erika emotions back to life..
What causes an oil spill to mark history is a combination of its size, the specific geographical location and the political context in which the response unfolds.
Discharging oil at sea is not totally prohibited
The International Maritime Organization has set the authorised concentration of oil in discharge from tankers and non tankers in the open sea at 15 parts per million (ppm).
In sensitive maritime zones (known as “special” zones), discharge from oil tankers is prohibited. Discharge of propulsion fuel and lubricating oil is authorised for non-tankers within the 15 ppm limit. All discharge is banned in the Antarctic special zone.
National regulation can set the thresholds
for discharge of hydrocarbons in the water by classified industrial plants, within limits determined according to the natural assimilation capacity of the surrounding environment. These regulations vary from one country to another.