The objectives of this field experiment were to observe the behavior and measure the residence times of crude oil and mousse applied to a wide range of shorelines. The range of residence times measured (from 3 days to more than 1 year), depended on the energy level, drainage, and sediment textural gradients. As would be expected, self-cleaning was generally faster on more exposed or waterlogged sandy beaches than on sheltered, muddy shores. Wet weather, the presence of microflora, and burial by sediments all affected the ease of visual identification of oil. Estimates of residence times from hydrocarbon analysis were therefore longer than those based on visual survey, except where large, immobile pebbles were oil coated. However, the two estimates produced a similar rank order of residence time. Mousse treatments resulted in more patchy oil distribution and less deep but more variable infiltration than did the crude oil. Visible contamination by the mousse was longer lasting and more obvious. Some oil treatments increased the firmness of the surface sediments and may thus have increased oil residence time. Poor drainage provides hydrological protection for sediments by limiting oil adherence and penetration, which is more or less independent of sediment type, compaction, and degree of exposure. Agreement with a published vulnerability index was otherwise good.

This content is only available as a PDF.