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Oil Spill

Water pollution

One of the most serious forms of water pollution has
most often used in the connection with losses of crude
oil, or petroleum, to marine environment. Best known
among these are the big tankers wrecks such as the
torrey canyon and the Exxon Valdez, the former spilling
860, 000 (107, 000 tons) of oil off the coast of
Cornwall, England, in 1967, and the latter some 240,000
barrels (30,000 tons) into Prince William Sound, Alaska,
in March 1989. The largest was some 2,160,000 barrels
(270,000 tons) resulting from the collision of two
tankers.

Oil discharged into the marine environment will be
degraded by physical, chemical and biological processes.
Evaporation of the oil occurs rapidly, with the violate
components evaporating off in approximately 24 hours.
The remaining heavier fraction of oil will be dispersed in
to the water as droplets, which will eventually be broken
down by bacteria and other micro-organisms. In some
cases water-in-oil emulsion will form, creating what is
known as "chocolate mouse" at the surface. The rates of
the above processes will be determined by weathers, sea
state, temperature and the oil type.

Then what happens?

Environment pollution

Oil floats on salt water (the ocean) and usually floats
on fresh water (rivers and lakes). Very heavy oil sometimes
sinks in fresh water, but this happens very rarely. Depending
on the circumstances, oil spills can be very harmful to
marine birds and mammals, and also can harm marine
animals. You may have seen dramatics pictures of oiled birds
and sea otters that have been affected by the oil spills.
Many birds also ingest (swallow) the marine animals and
died.

Have many reefs been damaged by spills?

Unfortunately, many past spills in coral reef
environments have been poorly documented, especially
those dating back several decades. Reviewing oil spills
from the Pacific, Caribbean, and Arabian regions, we
know that some events have caused destructive, long-
lasting impacts, while others have caused little long-
term impact to corals.
One comprehensive studied spill occurred at Bahia Las
Minas, Panama in April, 1986. An estimated 60,000-100,000
barrels of medium weight crude oil spilled into the waters of
the bay, causing widespread lethal and sub-lethal effects to
coral. In contrast, in the Arabian (Persian) Gulf Spill in
January 1991, the largest oil spill in history, an evaluated
6.3 million barrels of oil were released. Given the magnitude
of this release and the coral reef impacts noted at other
tropical spills, there were dire recognition of severe impacts
to reefs in Kuwait and Saudi Arabia. However, to date, the
extent of coral reef damage directly attributable to the
Gulf Spill has been remarkably minor.