Transcript Causes, Fate & Effects of Spilled Oil

Causes, Fate and Effects
of Spilled Oil
OPRC Level 3
Overview
OPRC Level 3
• Sources and Causes
• Fate and Behaviour
• Effects and Issues
• Case Studies
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Oil Inputs To The Marine Environment
OPRC Level 3
Land based
Scrapping ships
Tanker operations
Marine terminals
Tanker accidents
Non tanker accidents
Non tanker operations
(bilges & fuel oil)
Natural Atmosphere
Offshore production
Total= 2.35 Mt
Dry docking
Transportation
Source: IMO estimates
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Number Of Spills > 700 Tonnes
OPRC Level 3
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1970-79:
Spills per Year
10 Year Average
25.2 spills per y ear
on average
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25
20
1980-89:
9.3 spills per y ear
1990-99:
on average
15
7.8 spills per y ear
on average
2000-03:
3.5 spills per y ear
on average
10
5
0
1970
1972
1974
1976
1978
1980
1982
1984
1986
1988
1990
1992
1994
1996
1998
2000
2002
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Quantities Of Oil Spilt
OPRC Level 3
650
600
Atlantic Empress
C astillio de Bellver
ABT Summer
2 8 7 ,0 0 0 tonnes
2 5 2 ,0 0 0 tonnes
2 6 0 ,0 0 0 tonnes
550
500
450
(0 0 0 's of tonnes)
400
350
Khark V
8 0 ,0 0 0 tonnes
300
250
Exxon Valdex
Prestige
3 7 ,0 0 0 tonnes
7 7 ,0 0 0 tonnes
200
150
Erika
2 0 ,0 0 0 tonnes
100
50
1970
1972
1974
1976
1978
1980
1982
1984
1986
1988
1990
1992
1994
1996
1998
2000
2002
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Incidence of Spills by Cause 1974-2003
OPRC Level 3
<7 Tonnes
7-700 Tonnes
>700 Tonnes
Total
OPERATIONS
Loading/Discharging
2812
326
30
3168
548
26
0
574
1177
55
0
1232
Collisions
167
274
95
536
Groundings
228
212
114
554
Hull Failures
572
88
43
703
85
11
29
125
Other/unknown
2175
143
24
2342
TOTAL
7764
1135
335
9234
Bunkering
Other operations
ACCIDENTS
Fire & Explosions
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Loading / Discharging Oil
OPRC Level 3
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Bunkering Operations
OPRC Level 3
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Grounding
OPRC Level 3
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Collision
OPRC Level 3
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Spill Risk Factors
OPRC Level 3
• Quantity of oil transported
• Local navigation features:
–
–
–
–
traffic density
weather and sea conditions
visibility
water depth and nature of seabed
• Operations in progress:
– entering / leaving port
– loading / unloading / bunkering oil
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Oil Types
OPRC Level 3
• Crude oil
• Some refined products:
– Gasoline (petrol)
– Diesel
– Bunker C
– Lubricating oils
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Persistent and Non-persistent Oils
OPRC Level 3
Persistent
Non persistent
– many crude oils
– kerosene
– heavy products
– diesel oil
including fuel oil
– petrol
– lubricating oils
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Properties of Oil
OPRC Level 3
• Specific gravity / o API: density
• Viscosity: resistance to flow
• Pour point: temperature below which oil
does not flow
• Volatility: propensity to evaporate
• Asphaltene content: propensity to
emulsify
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Fate and behaviour of Spilled Oil
OPRC Level 3
Major processes:
• Drifting/movement
• Spreading
• Evaporation
• Emulsification
• Dispersion
Minor processes:
• Biodegradation
• Dissolution
• Photo-oxidation
• Sedimentation
• Shoreline interaction
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Fate of Oil Spilled at Sea
OPRC Level 3
evaporation
fragmentation
stranding
emulsification
spread
dispersion
biodegradation
sedimentation
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Relative Importance of weathering Processes
over Time
OPRC Level 3
0
Hours
1
10
Day
102
Week
103
Month
104
Year
Evaporation
Dissolution
Photo-oxidation
Biodegradation
Sedimentation
unstable
emulsion
Emulsification
Stable “mousse”
Dispersion
Spreading
Processes Over Time
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Main Effects of Weathering Processes
OPRC Level 3
EVAPORATION
•Reduction in volume
•Changes in oil properties
DISPERSION
•Reduction in volume
•Enhances biodegradation
EMULSIFICATION
•Increase in volume
•Change in properties and
colour
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Drifting at Sea
OPRC Level 3
3% wind
marina
time A
time B
100%
current
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Effects of Spilled Oil
OPRC Level 3
Impacts caused by:
• Toxic effects
• Physical effects
continued .
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Effects of Spilled Oil
OPRC Level 3
• Sensitive
environments(eg
mangroves, marshes,
mud flats)
• Tourism and leisure
activities
• Birds and marine
mammals
• Industry and water
intakes
• Fishing and
aquaculture
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Sensitive Environments
OPRC Level 3
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Birds and marine mammals
OPRC Level 3
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Tourism and Leisure Activities
OPRC Level 3
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Fishing and aquaculture
OPRC Level 3
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Industry and water intakes
OPRC Level 3
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Policy Issues
OPRC Level 3
•
•
•
•
•
•
Handling the media
Fishing bans
Bathing bans
Health risks to public and workers
Perceptions of damage
Environmental damage / monitoring
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Braer – United Kingdom, 1993
OPRC Level 3
• 84 000 tonnes of light crude oil
• High level of natural dispersion
• Relatively little clean-up/response
required
• Major impact on fisheries and
aquaculture
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OPRC Level 3
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Erika – France, 1999
OPRC Level 3
• 15 000 tonnes very persistent heavy fuel
oil
• Oil stranded over a long distance
• Difficult to observe from the air
• Highly viscous emulsion
• Problems: clean-up, access, disposal
• Impacts: fisheries, aquaculture, amenities
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OPRC Level 3
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Prestige – Spain, 2002
OPRC Level 3
• Cargo of 77,000 tonnes of heavy fuel
oil; unknown quantities released
• 800 km of Spanish beaches affected
plus impact on French coasts
• Significant oiling of coasts and waste
disposal problems
• Large impact on fishing
• Lesser impacts on aquaculture and
tourism industries
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OPRC Level 3
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OPRC Level 3
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Key Messages
OPRC Level 3
• Vast majority of spills are small (<7 t)
• Catastrophic tanker spills are rare
• Properties of spilt oil change over time:
this affects response options
• Oil spills can have a major impact on:
– Sensitive environments
– Tourism and leisure activities
– Industry, fishing and aquaculture
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