Oil spill dispersant article

CONTENTS
PREFACE ................................................................................................................................................................................... 3
INTRODUCTION ...................................................................................................................................................... 4
EFFECTS OF OIL SPILLS ............................................................................................................................ 4
OIL SPILL RESPONSE ....................................................................................................................................... 5
PRINCIPLE OF USING DISPERSANTS ............................................................................. 6
HOW DISPERSANT WORK .................................................................................................................... 7
WHAT DISPERSANT DO AND CANNOT DO ..................................................... 8
Spilled oil properties................................................................................................................................................ 9
Oil weathering .............................................................................................................................................................. 9
Dispersant type, application method and treatment rate ............................................... 10
THE ‘PROS’ AND ‘CONS’ OF DISPERSANT USE ........................................... 11
THE DISPERSANT DEBATE .................................................................................................................. 13
Case study 1
The Torrey Canyon oil spill
fi rst use of detergents on a massive scale .......................................................................... 13
After the Torrey Canyon .................................................................................................................................... 13
Oil spills in the 1970s, 80s and 90s ......................................................................................................... 15
The ecological effects of spilled oil ......................................................................................................... 15
The “fi sh versus birds” debate ..................................................................................................................... 18
Case study 2
The Braer oil spill - an example of natural dispersion of oil............................. 20
Exposure and toxicity ........................................................................................................................................... 19
Biodegradation of dispersed oil .................................................................................................................. 23
PLANNED USE OF DISPERSANTS ........................................................................................... 24
Quantifying the risk of using dispersants ......................................................................................... 24
NEBA (Net Environmental Benefi t Analysis) ............................................................................... 24
Comparing the outcomes of different response methods ............................................ 24
Case study 3
The Sea Empress oil spill - the use of oil spill dispersants ................................ 25
CONCLUSIONS ............................................................................................................................................................ 26
Putting dispersant use in the context of other options..................................................... 26
Concerns over dispersed oil........................................................................................................................... 26
Identifying the real unknowns and the real potential risks............................................. 26
Reassuring people that possible concerns have already been considered..... 27
SUGGESTIONS FOR FURTHER READING ............................................................... 27
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