This document discusses oil pollution and oil spills, including their impacts and management. It provides details on the types and transportation of petroleum oil, how oil spills occur, and the fate of spilled oil. It also examines several case studies of major oil spills throughout history, including impacts to marine life and ecosystems. Finally, it covers options for preventing and recovering from oil spills, such as designing safer tankers, training crews, responding to spills, and using booms, skimmers, and dispersants.

1. Oil pollution and oil spills
Impacts and Management
Source: Ecology of Aquatic Management, Chris Frid and Mike Dobson
(2002), pp 143-178

2. Petroleum Oil/ Crude oil
• Petroleum oil is a dark colored, mixture of flammable
hydrocarbons with different molecular weights. It is found in
liquid form in special geographic locations in the world in
underground pockets in the earth’s outer layer of rocks.
• Oil producers ship around 3 billion tones of petroleum oil per
year around the world for refinement.
• Crude oil is transported in oil tankers; they are huge ships that
can carry more than 200,000 tons of oil in one go.

3. A modern oil tanker

4. Modern oil tankers
A cargo ship

5. Oil spills and Oil slicks
• During oil transportation some oil is discharged from tankers either accidentally or
deliberately. This is called oil spills.
• Oil spills produce oil slicks.
• These oil slicks are carried away by winds and currents
• Oil spills and oil slicks cause oil pollution and sea water contamination.
When spilt on the
sea, oil tends to
form a slick on the
surface
Tanker is wrecked
into two halves

6. Fate of an oil spill
• Oil in the spill mixes with sea water and forms an emulsion at the surface. This
emulsion is called “chocolate mousse”.
• Small amount of the mousse is dissolved in sea water.
• Oil droplets begin to weather off by the volatilization and the photoxidation of
lighter volatile substances.
• Oil droplets thicken and become denser and tarry with time and sink to the sea
bed.
• Often, the tar accumulate debris forming tar balls, which may eventually be
cast ashore.
• The oil is slowly broken down naturally by aerobic bacteria where the rate is
dependent on the supply of oxygen and nutrients, i.e. nitrates and phosphates.

7. Biggest Oil Spills in
History

8. How It Happened:
An ill-maintained tanker exploded and later sunk off the coast of Italy. The accident killed
6 people. The Italians attempted to tow the Haven to shore, but failed, and the 820 ft-long
vessel sunk off the coast of Genoa. Today it is believed to be the largest shipwreck in the
world and is a popular tourist destination for divers.
The Cleanup:
Immediately after the incident, Italian authorities scrambled to fight the fire and control the
spread of the spillage using 6 miles of inflatable barriers that were submerged below the
water surface around the vessel. The rest of the surface oil was sucked up using vacuums.
M/T Haven Tanker, 1991
Location: Genoa, Italy
Gallons: 42 million

9. How It Happened:
In November 1988 the Liberian tanker Odyssey, virtually full to the brim with North Sea
crude oil, broke in two and sunk in the North Atlantic 700 miles off the coast of Nova Scotia.
It also caught fire as it sunk.
The Cleanup:
Because the incident took place so far from the coastline, the oil was expected to dissipate
naturally and no clean up response was conducted.
Odyssey , 1988
Location: 700 nautical miles off the coast
of Nova Scotia, Canada
Gallons: 43 million

10. How It Happened:
The tanker Amoco Cadiz ran aground off the coast of Brittany after its steering failed in a
severe storm. Its entire cargo of 246,000 tons of light crude oil was dumped into the roiling
waters of the English Channel.
The Cleanup:
Cleanup efforts were foiled by strong winds and heavy seas and less than 3300 tons of
dispersants were used. Within a month of the spill, 200 miles of the French shoreline was
contaminated with oil, which had the grim consequence of killing off more marine life than
any other oil spill at the time. Vacuum trucks and agricultural vacuum units were used to
suck up some of the oil, although a lot of it was simply removed by hand.
Amoco Cadiz, 1978
Location: Off Brittany, France
Gallons: 68.7 million

11. How It Happened:
The Castillo de Bellver caught fire about 70 miles northwest of Cape town, South Africa, on
August 6, 1983. The blazing tanker was abandoned and drifted offshore until it eventually
broke in half. The stern capsized and sank into the deep ocean, with some 110,000 ton of
oil remaining in its tanks. The bow section was sunk in a controlled explosion.
The Cleanup:
Cleanup was minimal. There was some dispersant spraying, but the environmental
consequences were small. About 1500 gannets gathered on a nearby island, were oiled,
but the impact on local fish stocks was minimal.
Castillo de Bellver, 1983
Location: Off Saldanha Bay, South Africa
Gallons: 78.5 million

12. How It Happened:
While en route to Rotterdam, the fully loaded tanker, ABT Summer, experienced an explosion
onboard and caught fire while it was 900 miles off the coast of Angola, leaking its payload
into the ocean. Surrounded by a growing oil slick that spanned 80 square miles, the tanker
burned for 3 days before sinking.
The Cleanup:
While no one can say how much of the oil sank or burned off, most of the oil is thought to
have been broken up by high seas at little environmental cost, thanks to the incident’s
offshore location.
ABT Summer, 1991
Location: Off the coast of Angola
Gallons: 80 million

13. How It Happened:
During the Iran-Iraq War, an oil tanker crashed into the Nowruz Field Platform in the Persian
Gulf and knocked it askew, damaging the well underneath. The oil well then leaked about
1500 barrels a day, but because it was in the center of a war zone, seven months went by
before it was fixed.
The Cleanup:
Norpol, a Norwegian company, used booms and skimmers to stem the spread of oil.
Nowruz Oil Field, 1983
Location: Persian Gulf
Gallons: 80 million

14. How It Happened:
Nearly 88 million gallons of oil spilled from an oil well in Fergana Valley, one of Uzbekistans’s
most active energy and oil-refining areas. While the spill didn’t get much press at the time,
it is the largest inland spill ever reported.
The Cleanup:
The ground absorbed this spill, leaving nothing for cleaning crews to tackle.
Fergana Valley, 1992
Location: Uzbekistan
Gallons: 87.7 million

15. How It Happened:
On July 1979, the Aegean Captain and the Atlantic Empress, two full supertankers, collided
off the coast of Tobago in the Caribbean Sea, precipitating the largest ship-sourced oil spill
in history. Both vessels began to leak their crude oil and caught fire. The Atlantic Empress
was towed out to sea until it exploded 300 nautical miles offshore. 26 people were killed.
The Cleanup:
The response to the incident included firefighting efforts and the use of dispersants to treat
the oil that spilled over the course of the accident and then while the Atlantic Empress was
towed away. Luckily, only minor shore pollution was reported on nearby islands.
Atlantic Empress, 1979
Location: Trinidad and Tobago, West Indies
Gallons: 88.3 million

16. How It Happened:
In June 1979, an oil well in the Bay of Campeche collapsed after a pressure
buildup sparked an accidental explosion. Over the next 10 months about 140
million gallons of crude spouted into the Gulf of Mexico from the damaged oil
well.
The Cleanup:
In order to slow down the flow of oil from the damaged well, mud, steel, iron
and lead balls were dropped down its shaft. Half the oil burned when it reached
the surface and a third evaporated. Dispersants were also sprayed over 1100
square miles of oil slick. Skimmers and boomers were placed in the water to
protect the bays and lagoons of the Barrier Islands.
Ixtoc 1 Oil Well, 1979
Location: Bay of Campeche, Mexico
Gallons: 140 million

17. How It Happened:
On April, 20, 2010, the Deepwater Horizon drilling rig exploded due to a methane gas release
from the well, immediately killing 11 and injuring 17 platform workers. The vessel burned for
almost two days and sank. The open well continued to leak oil into the Gulf until July 15, 2010.
The Cleanup:
As of August 2010, the clean up efforts are still underway. Approximately 75% of the oil is
unaccounted for. By July 30, more than 1.8 million gallons of dispersant were released into
the Gulf. By June 28, BP removed 890,00 barrels of oil liquid and burned about 314,000
barrels of oil. It is believed a large amount of the missing oil is lingering in subsurface layers of
the Gulf.
The clean up effort will continue for many years.
Deepwater Horizon, 2010
Location: Gulf of Mexico
Gallons: 206 million

18. Deleberately inflicted
by the Iraqi forces !!
How It Happened:
As Iraqi forces retreated from Kuwait during the first Gulf War, they opened the valve
of oil wells and pipelines in a bid to slow American troops. The result was the largest oil spill
history has seen, spanning an area just larger than the size of the island of Hawaii.
The Cleanup:
Coalition forces managed to seal off some of the open pipelines using smart bombs, but
most recovery efforts had to wait until after the war. Together with vacuum trucks about
58.8 million gallons of oil was recovered from the Gulf.
Gulf War, 1991
Location: Kuwait
Gallons: 240 to 336 million

19. During crude oil
extraction
water or CO2
is pumped in
for maximum oil
extraction

20. The Exxon Valdez oil spill, 1989
Alaska
• The Exxon Valdez oil spill occurred in Prince William Sound, Alaska, on
March 24, 1989. Spilled 260,000 to 750,000 barrels (41,000 to 119,000 m3)
of crude oil.
• It is considered to be one of the most devastating human-caused
environmental disasters. The Valdez spill was the largest ever in U.S. waters
until the 2010 Deepwater Horizen oil spill, in terms of volume released. The
oil was enough to fill a football stadium.

21. Case study:
Exxon Valdez – after effects of the oil spill
This 1989 crude oil spill occurred in the most biological active season
(March is spring to the northern hemisphere)
More than 1,900 kilometres of coast oiled
3,500 to 5,500 sea otter died
200 harbour seals died
144 species of dead birds collected
Estimated bird loss ranges from 260,000 to 580,000
60 to 70% colony reduction in Common and Thick-billed Murres

22. Intertidal habitats of the Prince William Sound showed surprisingly good recovery.
Many shorelines that were heavily oiled became clean in 1997 and appeared much
as they did before the spill. There are, however, still oil vestiges 10 years later the
oil spill.
Case study:
Exxon Valdez – Oil Reduction in Intertidal Shorelines

23. Global TREND IN OIL SPILLS

24. Impacts of a Major Oil Spill
1. Destroys Marine Life
2. Destabilizes Marine Communities
3. Degrades Shore Amenities
4. Harms Economic Activities
5. Impacts Human Welfare

25. 1. How does the oil spill destroy
Marine Life?
1. The aromatic fractions and the heavy metals in
oil are so toxic. If ingested lead to direct toxic
effects and mortality of birds and mammals.
2. Upon ingestion, oil chemically attacks the lipid
in the cell membranes of the gut epithelium. It
begins to die and slough off causing mortality to
birds and mammals.
3. Clean-up activities damage the marine life by
crushing and removing from the habitat.
4. Sea birds are oiled at the sea surface, loose their
insulation and either drown when they become
waterlogged, get hypothermia or die from oil
ingestion while trying to preen.
Marine birds and otters

26. 5. Oil can sink to the ocean floor and destroy the habitats of
benthic animals.
6. Oil can react with oxygen in the air to form acids that are
carried by wind and eventually fall back to the ground as acid
rain.
7. Oil washes up on beaches, coral reefs and marshes, and
threaten those habitats and the wildlife species there.
8. Sea turtles, whales, fish, otters and other animals can become
oil-soaked and die.
9. Dear, bears, wolves, dogs, and cats can die from eating oil-
soaked beach plants and animal carcasses.

27. 2. How does the oil spill
Destabilizes Marine
Communities and Populations?
Case study: Torrey Canyon wreck in the UK.
Rocky shore community of Cornwall were heavily
contaminated with oil.
Eg. Grazing gastropods and barnacles in rocky
shore were vulnerable to oil pollution
- gastopods were prevented from grazing by the
covering of oil,
- Barnacles ingested oil residues during filter-
feeding and suffered toxic effects.
Both groups were also highly sensitive to
dispersants and detergents that were used in the
clean-up.

29. • The gastropods were ‘key stone species in the
rocky shore community’
• In the absence keystone gastropods, the shore
soon exhibited a ‘green flush’ where the rocks
became covered with algae.
• It took nearly ten years for the damaged rocky
shore to recover to its former state.
• Therefore the ecological balance of a marine
community is shifted as some species in the
community are totally lost while others survive
with only limited mortality due to oil pollution.

30. A classification of the sensitivity of the natural
environment to oil spills
Shore type Sensitivity
Exposed rocky shores Least sensitive- High natural dispersion
Eroding wave cut platforms
Fine grained sand beaches
Coarse grained sand beaches
Exposed, compacted tidal flats
Mixed sand and gravel beaches
Gravel beaches
Sheltered rocky coasts
Sheltered tidal flats
Salt marshes and mangroves
Coral reefs Most sensitive- highly sensitive biota

31. 3. How does the oil spill Degrade
Shore Amenities?
1. Oil on the water’s surface can catch on
fire and pollute the air.
2. Contamination of coastal amenity areas
lead into public disquiet and concern
regarding impacts to boating, sun-
bathing, swimming, angling and other
recreational pursuits.
The degree of impact to recreation is
largely based on the season it occurred.
Summer being the highest impact period
due to recreation and tourism.

33. 5. How does the oil spill
Harm Economic Activities?
1. Oil can be tasted at very low
concentrations, giving contaminated
food a ‘taint’ and making it
unpalatable. Therefore, even if no
mortality occurs, fish caught near a
spill (open sea or aquaculture pond)
may be unmarketable.
2. Tourism, hotel and restaurant
businesses, dive and fishing charters,
rentals, marine operations could be
affected.
3. Frequently, the media press exaggerate
the impacts so that economic losses can
be massive beyond the actual.

34. 6. How does the oil spill
harm the Human Welfare?
A spill’s impact to human welfare is often
under-rated. Coastal communities, and
public in general, are deeply passionate
about a safe, clean marine environment.
There is no tolerance for accidental spills
of oil of any quantity. As such a marine oil
spill accentuates this passion, often beyond
rationale thinking.
During an incident, public stress and
anxiety prevail over the long-term
economic uncertainty of lost welfare. In
addition, a large influx of spill money can
divide a communities from those the
volunteer from their “hearts” and those the
offer their services for a “fee”.

35. Management of oil pollution
Basically, two options;
• Prevention
• Recovery

36. 1. Prevention
1. Design safer oil tankers.
Double lined bottom instead of single metal layer.
Separate compartments for oil storage. In a double-
hull tanker, the cargo tanks are separated from the
ships outer hull to protect against the impact of an
accident.
2. Thorough training of tanker crews.
–Develop better emergency procedures.
–Improve navigation skills.

37. 3. The petroleum industry should work closely with
government agencies, universities and research centers to
combat the menace of oil spill incidents.
4. Prepare a coastal Inventory and Shoreline Oil Sensitivity
Mapping. When a spill occurs, Canada utilizes the Shoreline
Cleanup and Assessment Team (SCAT) process adopted
from Alaska to determine when and how each individual
shoreline will be cleaned based on geomorphological,
ecological and archaeological factors.

38. • There are four basic options for dealing with
an oil spill
1. Monitor only
2. Disperse
3. Contain and recover
4. Shore clean-up methods
2. Recovery

39. 1. Monitor only
• This allows for natural dispersion to occur by
currents and waves.
• The best environmentally friendly option.
• However, the press and the public often see
this option as an attempt of the oil polluter and
the authorities to save money by doing
nothing.

40. 2. Disperse
• Oil slick is broken up to small droplets
creating a greater surface area for natural
weathering and biodegradation.
• Ships towing breaker boards
• Spraying Chemical dispersants
manually or by low flying aircrafts

42. Booms are giant Styrofoam logs wrapped in plastic that act like a floating fence.
Then vacuum up spilled oil with skimmer boats. A skimmer is a boat with special
equipment that collects oil from the surface of calm waters.
About 10-15% of the spill could be recovered preventing further damage.
Effective only in the quite seas
1. Contain the spill with oil booms and skimming the spill
3. Contain and recover

44. 4. Clean-up method
• Many methods are available here.
• In a shore, clean-up will damage more than the damage caused by the oil
pollution.
• Properties of Oil that Affect Cleanup
1. Viscosity
A measure of a fluid’s resistance to flow. The hotter a fluid, the more easily it
flows. Oil spilled in the cold waters of Alaska spreads slower than oil spilled
off the warm coast of South America.
2. Density
A measure of how heavy a substance is in a fixed amount of volume. Many
oils float on top of water because they are lighter than water.
3. Absorptivity
A measure of how easily a fluid is absorbed, or soaked up, by a different
material. Engineers use absorbent pillows to soak up spilled oil.

45. 1. Physical removal of oil from a beach by scrape
blades and suction pumps

46. 2. Bioremediation of oil spills
Biodegrade the oil by spreading microbes on beaches.

47. Bioremediation
1. Initially oil cleaning bacteria were produced by genetic engineering. – Not very effective
though.
2. Several naturally occurring Pseudomonas bacteria were used next under aerobic conditions ,
and their growth was enhanced by spraying nitrogen and phosphorous plant fertilizers.
3. The number of bacteria increased significantly and the oil spill was degraded by fully
cleaning the beach.

48. 3. Absorb the oil with sawdust, straw, foam chips, or
other oleophilic sorbents.
4. Use chemicals to disperse the oil into small droplets
and let it drift out to sea.
5. Beach washing with detergents
6. Steam jetting
7. Low or high pressure washing.
8. Removal of oiled substrata/biota
Heavily oiled sand could be bulldozed
Macro-algal fronds that trapped oil are cut and
sent for disposal

49. Cleaning oiled birds and animals
This is not always successful. The birds are weak from
struggling in the oil and may be ill from digesting oil while
trying to clean their feathers.

51. Though a high number of
individual animals may have
been killed, the actual initial
impacts to communities
(populations) of salmon, sea
otters, harbour seals and sea bird
was low. Indications show that
wildlife species populations
have recovered within their
natural range of variability.
End of lecture