There is no doubt that in the case of oil spills, the old adage 'prevention is better than cure' has never been truer. However, with ever increasing oil exploration and distribution, the opportunities for spills are now greater than ever. Many spills result from human error and from severe weather conditions. However, economic factors also come into play. There is no doubt that in the case of tanker spills, many could be prevented if all tankers were built with double hulls. Several incidences where such ships have run aground and gashed their hulls without spilling any oil bear testament to this.
Various measures are used for the protection of beaches from oil pollution, when it occurs. Permanent and temporary floating booms and barriers may be used to prevent entry of oil into inlets and estuaries. In Sullom Voe in Shetland, where there is a massive oil terminal, such barriers are kept permanently on station at the various arms of the loch, ready for deployment. Temporary booms were used in the Exxon Valdez disaster to prevent the entry of oil to salmon hatcheries. Spilt oil may also be impounded with booms and skimmed up. All such booms are often rendered ineffective by waves or currents.
It is now generally accepted that there is no single clean-up method appropriate for all spills. Each spill is different and careful assessment is needed before deciding on a course of action (IPIECA, 1991; IMO/IPIECA, 1996). The action taken must be capable of significantly reducing the recovery time of the shore to below that which natural weathering will achieve. Sometimes cleaning may be undertaken for economic and amenity reasons rather than for the wildlife alone.
Even in recent incidents, clean-up operations have sometimes increased the impacts and extended the recovery time for marine populations. These have usually been where aggressive techniques such as the use of high-pressure hot water (e.g. Exxon Valdez spill) and excessive use of dispersants (e.g. Torrey Canyon) have been used. These methods often kill off key species that have survived the initial oiling. However, even attempts to use non-aggressive mechanical clean-up methods can be damaging when used inappropriately. When attempting to clean mangrove areas, long-term damage has often been done by the heavy vehicles needed to get into the area.
Mechanical clean-up methods can sometimes be used to remove bulk oil and these generally cause little damage provided they can be used with minimal trampling, and may also prevent further pollution from mobile oil. Suction pumps collect oil from gullies, and rockpools or from trenches dug to collect it. Straw bales and a variety of absorbent materials can be used to mop up small areas of surface oil. A privately developed 'mat' sandwich of straw, which can be unrolled onto the surface of the water, is being used very successfully for small spills, especially in fresh water. Low-pressure flushing with water at ambient temperature washes shores, with little physical damage to marine life but requires booms, skimmers and a large team to collect the oil. Oiled weed and other debris can be collected by hand and oil-saturated sand dug up and dumped elsewhere.
Chemical dispersants have been much used for beach cleaning, especially on British shores. They soon make the beach more pleasant for human enjoyment, but have often proved much more damaging to intertidal organisms than the oil itself. Modern dispersants have low toxicity and may sometimes be appropriate for shore clean-ups. Nowadays they are more usually used on offshore slicks to prevent their coming ashore. They may, however, cause the oil to disperse into the water column, sink and affect the benthos. Even so, dispersants might be used, for example, to prevent oil entering a sensitive mangrove area whilst accepting there might be some detrimental effects to nearby coral reefs (IPIECA, 1992; 1993).
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