Monday, June 21, 2010


I found this very interesting site that provided a student guide to oil spills.  In Nigeria spills are commonplace at the Niger River Delta. This also support my theory in a previous post about making the Mississippi Delta the focal point of oil collection and decontamination.

What happens after a spill occurs?

Response teams often protect sensitive areas with booms (floating barriers) and help oiled wildlife by cleaning birds and fur-bearing mammals with detergent. The most common cleanup techniques are outlined below:
  • Containment and recovery: Surround the oil with booms and recover the oil (for cleaning and reuse) with skimmers. Skimmers separate oil from the water by:
    • centripetal force -- water is heavier than oil and spins out further so the oil can be pumped out
    • lifting oil on a conveyor belt off the water surface; or
    • wringing out the oil that clings to oleophilic (oil-attracting) rope mops.
    This technique is the most widely used as it is least destructive, but it is only 10-15% efficient under even the best circumstances.
  • Sorbents: Remove oil with absorbent sponges made from diaper-like substances. Some sorbents are made from natural materials -- straw, grasses, coconut husks, or wood chips.
  • Dispersants: These are chemicals that act like detergents to break oil up into tiny droplets to dilute the oil's effect and to provide bite-sized bits for oil-eating bacteria that occur naturally, particularly in areas that have had a history of oil spillage.
  • Burning: Burning is usually 95-98% efficient, but does cause black smoke. The smoke is not more toxic than if the oil were burned as intended in fuels. One gallon of oil burned this way creates the same pollutants as three logs in a fireplace or woodstove.
  • Bioremediation: Enhancing natural biodegradation by natural oil-eating bacteria by providing them with needed fertilizers or oxygen.
  • Shoreline cleanup: High-pressure hosing to rinse oil back into water to be skimmed up. This usually does more harm than good by driving the oil deeper into the beach and by killing every living thing on the beach. This was used extensively after the Exxon Valdez spill due to public and state pressure to make the beaches "look clean again," despite the known risks. Areas left alone to be weathered by winter storms were shown to be cleaner and harboring more life than those cleaned by high-pressure washing. (Short term aesthetic considerations should not override the more basic longer term ecological considerations in rehabilitating a beach.)
  • Do nothing: Particularly in open ocean spills, cleanup is difficult and not efficient. Wave action and photo-oxidation (from sun) helps to break oil down.

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