definition 112 causes, effects and control measures of

CASE STUDY

One of the worst oil spill disasters that have

occurred is that of the Exxon Valdez. On 24

th

march 1989 the Exxon Valdez, a tanker more

than three football fields wide went off

course in a 16 kilometer wide channel in

Prince William Sound near Valdez in Alaska.

It hit submerged rocks, creating an environ-

mental disaster. The rapidly spreading oil slick

coated more than 1600 kilometers of shore-

line killing between 300,000 and 645,000

water birds and a large number of sea ot-

ters, harbor seals, whales and fishes. Exxon

spent $ 2.2. billion directly on the clean-up

operations. However some results of the

cleanup effort showed that where high pres-

sure jets of hot water were used to clean

beaches coastal plants and animals that had

survived the spill were killed. Thus it did more

harm than good. Exxon pleaded guilty in

1991 and agreed to pay the Federal Gov-

ernment and the state of Alaska $ 1 billion

in fines and civil damages. This $8.5 billion

accident might have been prevented if Exxon

had spent only $22.5 million to fit the tanker

with a double hull-one inside the other. Such

double hulled vessels would be less likely to

rupture and spill their contents. The spill high-

lighted the need for marine pollution pre-

vention.

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Environmental Studies for Undergraduate Courses

is another source of pollution. Accidental oil spills

from large transport tankers at sea have been

causing significant environmental damage.

Though accidents such as the 

Exxon Valdez get

worldwide attention, much more oil is released

as a result of small, regular releases from other

less visible sources. Nearly two thirds of all ma-

rine oil pollution comes from three sources: run-

off from streets, improper discharge of

lubricating oil from machines or automobile

crankcases and intentional oil discharges that

occur during the loading and unloading of tank-

ers. Oil tankers often use sea water as ballast to

stabilize the ship after they have discharged their

oil. This oil contaminated water is then dis-

charged back into the sea when the tanker is

refilled.