ABSTRACT
Between 60,000 and 65,000 tons of the Amoco Cadiz oil came ashore along approximately 70 km of the shoreline of Brittany during the first few weeks of the spill (March 16–30, 1978). A prevailing westerly wind pushed the oil against west-facing headlands and into shoreline embayments as it moved east. A wind reversal in early April moved the oil in the opposite direction, contaminating previously untouched areas and transporting the oil as far southwest as Pointe du Raz (southwest of Brest). At the end of April, the total volume of oil onshore was reduced to approximately 10,000 tons but by that time more than 300 km of shoreline had been contaminated.
The details of oil erosion and burial were determined by resurveying 19 permanent beach profiles established during the first few days of the spill. These stations, plus an additional 147 beach observation stations, were revisited one month after the spill.
Coastal processes and geomorphology played a major role in the dispersal and accumulation of the oil once it came onshore. For example, oil accumulated at the heads of crenulate bays and on tombolos (sand spits formed in the lee of offshore islands). Local sinks, such as scour pits around boulders, bar troughs (runnels), marsh pools, and joints and crevasses in rocks, tended to trap oil.
Classification of the coastal environments of the Amoco Cadiz oil spill site, according to an oil spill vulnerability index (scale of 1–10 on basis of potential oil spill damage), revealed a good correlation with earlier findings at the Metula and Urquiola oil spill sites. For example, exposed rocky coasts and wave-cut platforms (stations 1 and 2) were cleaned of extremely heavy doses of oil within a few days. Sheltered rocky coasts (station 8), sheltered tidal flats (station 9) and estuarine marsh systems (station 10) proved to be the most vulnerable of all coastal environments to oil spill damage. These observations provide encouragement and incentive to continue to apply the vulnerability index to areas in the United States threatened by potential oil spills. The Brittany coastline is particularly analogous to the coastline of Maine and parts of southern Alaska.
Aspects for Priority Protection Assessment of Abiotic Components to Oil Exposure