Environmental Engineering Reference
In-Depth Information
9.3
Impact of Oil Spills on
Environment and Society
solution. Polar fraction increases and aromatic
fraction decreases in petroleum when subjected
to photochemical oxidation under sunlight (Dutta
and Harayama
2000
). Biodegradation of crude
oil also results in similar changes in its composi-
tion, with loss of saturated and aromatic hydro-
carbons and relative increase in polar fractions
(Head et al.
2006
).
Nature of oil (physical and chemical proper-
ties) and natural conditions (water, temperature,
weather, and topography of surrounding area)
prevailing at the time of oil spill influence the
weathering and biodegradation of oil. Oil spills
contaminate drinking water, disrupt food chain,
endanger public health, destroy natural resourc-
es, and disrupt economy. Thus, it is of utmost im-
portance to develop
in situ
strategies for cleanup
of marine oil spills (Fig.
9.1
).
Flora and fauna as well as the topography of the
surrounding areas bear the brunt of oil spills. An-
imals may be smothered in oil and killed or seri-
ously injured soon after coming in contact with
oil. However, many other effects of oil spills are
more subtle and long lasting.
Aquatic animals like turtle, seal, walrus, and
dolphin which live close to the shore, endanger
themselves when they consume oil-contaminated
prey. Kelps and sea grasses are often used for
food, shelter, and nesting by birds and aquatic
animals. These are destroyed by oil contamina-
tion, thus affecting their reproductive cycle and
nursing of the young. Direct physical contact
of oil with fur of mammals causes loss of their
insulating properties, leading to hypothermia-
induced death. Feathers also lose their architec-
ture as well as their insulating properties, which
help birds in keeping warm, flying, and floating,
when in contact with oil. Seepage of oil onto the
surface of eggs often seals their pores and pre-
vents gaseous exchange leading to the death of
the embryo. Aquatic mammals and birds often
starve to death when they refuse to eat oil-stained
unpleasant-smelling prey (EPA
1999b
).
Coral reefs, which serve as nurseries for fin-
gerlings of fish, are often smothered in oil and
risk exposure to toxic substances in oil. Tidal
flats, sheltered beaches, salt marshes, and man-
grove forests harbor rich biodiversity, which on
exposure to oil, gets disturbed, damaged, and de-
stroyed (EPA
1999b
).
Human activities like fishing, aquaculture,
recreational activities, tourism industry, and
human health are adversely affected because of
oil spills. Fishing and shellfish fishing are often
closed to prevent catching oil-tainted fish. Severe
economic losses are incurred by tourism indus-
try and operators of recreational activities (scuba
diving, angling, and boating). Water is often used
for cooling purposes in nuclear desalination,
and power plants. These industries risk intake of
oiled water into their piping and machinery. Per-
sonnel engaged in containment of oil spills risk
ill health by inhaling or touching oil products and
9.2
What Are Oil Spills?
Accidental or incidental release of liquid petro-
leum hydrocarbon into the environment (marine
or inland) due to human activity is called oil spill.
During Gulf War (1991), retreating Iraqi forces
opened valves of oil wells and pipelines and set
them to fire in a bid to slow down onslaught of
invading American forces. An estimated 240-
360 million ga of crude oil flowed into Persian
Gulf. This exacted little damage to the marine eco-
system as per a report by the Intergovernmental
Oceanographic Commission at UNESCO. Deep-
water Horizon/BP oil spill (2010) caused by well-
head blowout at the Deepwater Horizon oil rig is
the most devastating and the largest marine oil
spill. The explosion at the rig killed 11 men work-
ing on the platform and injured 17 others. It spilled
220 million ga of oil into the Gulf of Mexico, caus-
ing extensive damage to gulf's fishing and tourism
industry. Though Exxon Valdez oil spill (1989) is
the second largest oil spill in the USA, it is notable
because it led to serious reexamination of policies
and framework for oil spill cleanup in the country.
It occurred in Prince William Sound, Alaska, when
Exxon Valdez, an oil tanker, ran aground, releas-
ing 10.8 million ga of crude oil, which impacted
1609 km of Alaskan coast. Table
9.1
lists some of
the largest oil spills in the world.
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