Case Histories - A

ABT SUMMER (Off Angola, 1991)

On 28th May 1991, while en route from the Gulf terminal at Kharg Island, Iran to Rotterdam the tanker ABT SUMMER, fully laden with a cargo of 260,000 tonnes of Iranian heavy crude oil, experienced an explosion and a fire about 900 miles off the coast of Angola. Five of the 32 crew members on board died as a result of the incident.

A large slick covering an area of 80 square miles spread around the tanker and burnt fiercely. The ship burned for three days before it sank on 1st June and subsequent efforts to locate the wreckage were unsuccessful.

It is not clear how much of the oil sank or burned. However, as the incident occurred very far off-shore, most of the oil was expected to be broken up by high seas with little or no environmental impact.

Selected Bibliography

Hooke, N. (1997) Maritime casualties, 1963-1996.  2nd edition, LLP Limited, London

Oil Spill Intelligence Report, 30 May 1991 & 6 June 1991


CEDRE - Case history


AEGEAN SEA (Spain, 1992)

Smoke over La CorunaOn 3 December 1992 the Greek OBO carrier (ore/bulk/oil) AEGEAN SEA, laden with 80,000 tonnes of North Sea Brent crude oil, ran aground during heavy weather while approaching the port of La Coruna on the Galician coast, North West Spain.  The vessel broke in two and caught fire.  Ship and spilled cargo burned for several days, causing dense clouds of black smoke to threaten the city of La Coruna, leading to a temporary mass evacuation.

The forward section of the AEGEAN SEA sank in shallow water some 50 metres from the coast.  The stern section remained largely intact and was found to contain 6,500 tonnes of remaining cargo and 1,700 tonnes of bunker fuel which was eventually pumped ashore by salvors. 

Strong winds over the first five days helped to disperse much of the light crude naturally, but also hampered recovery of oil at sea.   Attempts at recovering oil from natural collecting points on-shore were more successful. 

The quantity of oil spilt was estimated at about 74,000 tonnes, much of which either dispersed at sea or was consumed by the fire on board the vessel. Spilt crude oil also impacted rocky shores, small sandy beaches and a salt marsh/mud flat area. In total, over 300km of shoreline were contaminated to varying degrees. Manual cleaning of shorelines began in late December and continued sporadically for several months.  Collected oily waste was delivered to a local ceramics factory for disposal.

A variety of commercially important species, including mussels, were tainted and a comprehensive fishing and harvesting ban was imposed to protect a thriving fishing and mariculture industry.

Selected Bibliography

Hooke, N. (1997). Maritime casualties, 1963-1996. 2nd edition, LLP Limited, London

Pastor, D., Sanchez, J., Porte, C. and Albaigés, J. (2001). The Aegean Sea Oil Spill in the Galicia Coast (NW Spain). I. Distribution and Fate of the Crude Oil and Combustion Products in Subtidal Sediments. Marine Pollution Bulletin 42: 895 – 904.

Porte, C., Biosca, X., Sole, M., Pastor, D. and Albaigés, J. (1996). The Aegean Sea Oil Spill One Year After: Petroleum Hydrocarbons and Biochemical Responses in Marine Bivalves. Marine Environmental Research 42: 404 – 405.


CEDRE - Case History

International Oil Pollution Compensation Funds (IOPC Funds)


AMOCO CADIZ (France, 1978)

AMOCO CADIZThe tanker AMOCO CADIZ ran aground off the coast of Brittany on 16 March 1978 following a steering gear failure. Over a period of two weeks the entire cargo of 223,000 tonnes of light Iranian and Arabian crude oil and 4,000 tonnes of bunker fuel was released into heavy seas. Much of the oil quickly formed a viscous water-in-oil emulsion, increasing the volume of pollutant by up to five times. By the end of April oil and emulsion had contaminated 320km of the Brittany coastline, and had extended as far east as the Channel Islands.

Strong winds and heavy seas prevented an effective offshore recovery operation. All told, less than 3,000 tonnes of dispersants were used. Some chalk was also used as a sinking agent, but with the consequence of transferring part of the problem to the sea bed. The at-sea response did little to reduce shoreline oiling. A wide variety of shore types were affected, including sandy beaches, cobble and shingle shores, rocks, seawalls and jetties, mudflats and saltmarshes. Removal of bulk free oil trapped against the shore using skimmers proved difficult, largely due to problems with seaweed and debris mixed with the oil. Greater success was achieved with vacuum trucks and agricultural vacuum units, although much of the free oil was simply removed by hand by more than 7,000 personnel (mainly military). A considerable portion of the oil that did come ashore eventually became buried in sediments and entrapped in the low energy salt marshes and estuaries.

At the time, the AMOCO CADIZ incident resulted in the largest loss of marine life ever recorded after an oil spill. Two weeks after the accident, millions of dead molluscs, sea urchins and other benthic species washed ashore. Although echinoderm and small crustacean populations almost completely disappeared from some areas, populations of many species had recovered within a year. Diving birds constituted the majority of the nearly 20,000 dead birds that were recovered. Oyster cultivation in the estuaries ("Abers") was seriously affected and an estimated 9,000 tonnes were destroyed because of contamination and to safeguard market confidence. Other shell and fin fisheries as well as seaweed gathering were seriously affected in the short-term, as was tourism. Cleanup activities on rocky shores, such as pressure-washing, as well as trampling and sediment removal on salt marshes caused biological impacts. Whilst rocky shores recovered relatively quickly, the salt marshes took many years. Failure to remove oil from temporary oil collection pits on some soft sediment shorelines before inundation by the incoming tide also resulted in longer-term contamination. Numerous cleanup and impact lessons were learned from the AMOCO CADIZ incident, and it still remains one of the most comprehensively studied oil spills in history.

Selected Bibliography

Bellier, P. and Massart, G. (1979). The Amoco Cadiz oil spill cleanup operations - an overview of the organisation, control and evaluation of the cleanup techniques employed. Proceedings of the 1979 Oil Spill Conference, 141-146. API Publication No. 4308. American Petroleum Institute, Washington, DC, USA

NOAA (1978). The Amoco Cadiz oil spill: A preliminary scientific report. A National Oceanic and Atmospheric Administration and Environmental Protection Agency special report, Washington DC, USA

Spooner, M.F. (editor) (1978). The Amoco Cadiz oil spill. Special edition of Marine Pollution Bulletin 9 (7). Pergamon Press, Oxford and New York

Conan, G., d'Ozouville, L., and Marchand, M. (1978). Amoco Cadiz - preliminary observations of the oil spill impact on the marine environment. One day session, Amoco Cadiz, Brest, France, 7 June 1978. Le Centre National pour l'Exploitation des Oceans, Paris, France


CEDRE - Case History


ARGO MERCHANT ran aground on Nantucket Shoals, off Massachusetts, USA, on 15 December 1976, and over the next month spilled her entire cargo (28,000 tonnes) of Venezuelan No 6 fuel oil and cutter stock. Storms broke up the tanker after grounding, and attempts to pump the oil into another vessel failed. In-situ burning was attempted on two occasions, but the slick failed to remain alight.

Winds during the spill period were offshore from Massachusetts, and as a result no oil from ARGO MERCHANT ever reached the shoreline and no coastal impact was reported. Hydrocarbon contamination of the bottom sediments was restricted to an area immediately around the wreck, and apparently was short-lived. The bulk of the spill formed large 'pancakes' and sheens on the surface; these were carried offshore over the continental shelf and into the prevailing North Atlantic circulation pattern. The cutter stock, which was mixed with the fuel oil to improve handling, entered the water column. Despite its relatively high potential toxicity, there was little evidence of impact on the marine fauna or phytoplankton. The accident occurred at the time when the fewest potential effects on pelagic organisms would be expected; a period of low productivity in the water column, with few fish eggs and larvae present. Oiled birds were seen near the wreck, and though total mortalities are difficult to evaluate, it was concluded that the spill probably had little effect on the coastal and marine bird populations off the New England coast. The outcome of the ARGO MERCHANT oil spill appears to have been fortunate in several respects: - the winds were almost continuously offshore, preventing the oil from coming on the beaches; the density of the oil was low enough so that it did not sink and contaminate the bottom, and the spill occurred in the winter when the biological activity, productivity, and fishing activities are relatively low.

Selected Bibliography

Winslow, R. (1978). Hard aground: The story of the Argo Merchant oil spill. W.W. Norton & Company Inc, New York, USA

Grose, P.L. & Mattson, J.S. (editors) (1977). The Argo Merchant oil spill: A preliminary scientific report. Govt Print. Off. [for] Department of Commerce, National Oceanic and Atmospheric Administration, Washington, DC, USA

Center for Ocean Management Studies (1978). In the wake of the Argo Merchant. Proceedings of a Symposium, 11-13 January 1978. University of Rhode Island, USA


ATLANTIC EMPRESS (West Indies, 1979)

On 19 July 1979 two fully loaded VLCCs (very large crude carriers), the ATLANTIC EMPRESS and AEGEAN CAPTAIN, were involved in a collision approximately 10 miles off Tobago during a tropical rainstorm. Both vessels began leaking oil immediately after the collision and both caught fire.  Several crewmen lost their lives.

The fire on board the AEGEAN CAPTAIN was brought under control and the vessel was eventually towed to Curacao where its remaining cargo was discharged. The still blazing ATLANTIC EMPRESS was towed further out to sea on 21 and 22 July.  A week later, when 300 nautical miles offshore, a large explosion caused severe damage to the vessel; it began to list and eventually sank on 2 August.

The response to the incident involved a significant fire-fighting effort and use of dispersants to treat the oil that was spilled during the original incident and while the vessel was being towed.

An estimated 287,000 tonnes of oil was spilled from the ATLANTIC EMPRESES, which makes this the largest ship-source spill ever recorded.  No impact studies were carried out, so it is not known what quantity of oil was burned or sank.  Only very minor shore pollution was reported on nearby islands.   

Selected Bibliography

Hooke, N. (1997) Maritime casualties, 1963-1996.  2nd edition, LLP Limited, London




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