Urhobo Historical Society thanks
Oil
Spill Intelligence Report, Arlington, MA, U.S.A. for this report and for
permiting it to be distributed.
This
summary was designed to provide background information for students and
members of the general public on spill-related topics. You may copy and
distribute this information freely provided that the source is attributed
as Oil Spill Intelligence Report, Arlington, MA, U.S.A.
For
more information about the Oil Spill Intelligence Report newsletter, contact
the Client Services department by phone at 781/641-5125, by fax at 781/648-8707,
or by e-mail at dcrowley@cutter.com.
This fact sheet was written
with students and the general public in mind. You may distribute this information
freely provided that the source is attributed as Oil Spill Intelligence
Report, Arlington, MA, U.S.A.
Every year 100 million US gallons
of oil spill. This is equal to 100 school gymnasiums:
Typical school gymnasium = 45' X 45' X 66'
= 133,650 cubic feet
1 cubic foot = 7.481 gallons
Gym holds 999,387 gallons (almost 1 million gallons).
The biggest spill ever occurred
during the 1991 Persian Gulf war when about 240 million gallons
spilled from oil terminals and tankers off the coast of Saudi Arabia. The
second biggest spill occurred over a ten-month period (June 1979 - February
1980) when 140 million gallons spilled at the Ixtoc I well blowout
in the Gulf of Mexico near Ciudad del Carmen, Mexico. But even all the
oil spilled during the Persian Gulf spill is only about 1/3 of what the
US uses in one day!
The Exxon Valdez spill
in Alaska was approximately 11 million gallons. That spill was only
about the 35th largest in the world, though it was the largest in the US.
It came from a huge supertanker that was about the size of 15 gyms in length
X 4 gyms wide X 2 gyms deep (which held 66 million gallons).
Why does all
that oil spill?
We use a lot of oil and it
needs to be transported. The US uses 710 million gallons per day. In fact,
every 22 minutes, the US uses up what spilled in the Exxon Valdez spill.
The world uses 2.73 billion gallons (2,730 gyms full) per day.
Every day 31.5 billion
gallons of oil are at sea being transported. But not all spills come from
tankers. Some comes from storage tanks, pipelines, oil wells, tankers and
vessels cleaning out tanks.
What is all that
oil used for?
Fuel (for transportation and
factories)
Electricity generation
Machinery
Asphalt
Heating
Wax (crayons, candles)
Medicines
Ink
Plastics
Fertilizers
Pesticides
Paints/varnishes
How does it spill?
Accidents: often through carelessness
Sometimes unavoidable events:
weather, earthquakes
Intentional spills: terrorists,
war, vandals, dumping
What happens
to oil when it spills?
Oil generally floats because
it is lighter than water.
A good experiment to do
here is to add vegetable oil, which acts like crude oil, to food-colored
water in a large, clear plastic soda bottle with a cap. Shake it and watch
how the oil always settles on top.
30-40% evaporates in the
first 24-48 hours; these are the most poisonous (toxic) portions, as well
as the portions that are the most soluble, and flammable.
Oil tends to float and spread
out into a very thin film on the water surface...usually only about 0.1
mm thick...then spreads even thinner to a sheen, which is one tenth or
one one-hundredth of this. Sheens are often seen as rainbow-like or silvery
in puddles in parking lots.
It is very rare for oil
to sink. It needs to adhere to heavier particles such as sand, algae, or
silt to sink. An exception is a kind of oil used for burning in electric
utility plants. This oil can actually sink in water since it is heavier
than water.
What are the
environmental impacts?
These impacts are very often
grossly exaggerated in the public media. Environmentalist groups have been
notorious in spreading misinformation about environmental effects. Nevertheless,
oil can have a significant impact on marine larvae, birds and mammals in
particular, and to a lesser extent on fish.
Some components of oil are
toxic if exposure occurs within the first two days of a spill (1 part per
million [ppm], i.e. one gallon in one million gallons, can be toxic to
invertebrate larvae; 1000 ppm for fish). Oil on feathers hinders the water-repellancy
of the bird. Oil on fur takes away its insulating capacities.
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.
Who else might
be affected by an oil spill?
Fishing industry, resorts and
recreation areas, water supplies for drinking and industry.
What about prevention?
Since cleanup after an oil
spill is so ineffective and so difficult, and does not always fully rehabilitate
affected areas, prevention is most important. Effective prevention
plans might include:
improved piloting; training
of ship and tanker crews
training of storage and pipeline
facility crews
enforcing pollution rules at
sea
building more spill-resistant
vessels
maintaining vessels and pipelines
preparing for spill response
through effective training, planning (contingency planning), and practice
drills.
What can students
do?
Don't spill used motor oil.
Return used oil to a service station for proper disposal at a facility
that will clean and recycle the oil. Reduce usage of fuels, electricity,
and plastics.
