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Autor: anton • December 3, 2010 • 873 Words (4 Pages) • 321 Views
There was absolutely devastating damage to the ecosystems of Alaska caused by the Exxon Valdez tragedy. The crude oil covered a huge area of 460 miles in total, with 1300 miles of affected coastlines. 200 of these miles were affected very heavily. Over 11000000 gallons of oil escaped from the tanker and devastated the wildlife, mainly marine.
Carcasses of organisms killed by oil usually sink to the floor of the ocean, so no-one knows how many organisms were killed. Estimates soar at 250000 sea birds, 2800 sea otters, 300 harbor seals, 250 bald eagles, up to 22 killer whales and billions of salmon and herring eggs. The food webs were understandably disrupted, with all levels of consumers and producers being affected. The oil created a film over the water, through which neither oxygen nor light could penetrate. Without enough light, the producers in the environment could not photosynthesize, depriving all the organisms in the vicinity of food. The consumers could not breathe if they lived underwater, with the oil blocking the oxygen from the water. With so many eggs being destroyed, the populations of those fish are still recovering.
After the spill on March 24, a trial burn was conducted. A suitably uninhabited area was surrounded by a fireproof boom and lit. The burn worked relatively successfully, but weather conditions (i.e. storms) prevented any more burns during the clean up. After the burn, mechanical help was called in, with ships trailing massive booms and skimmers. The skimmers were not readily available for 24 hours after the spill however, and got clogged by the thick oil and kelp. The thickness and weight of the oil also made transporting it to permanent storage areas difficult. Dispersants were also trialed (i.e. chemicals which separated the oil as does detergent) but due to the lack of dispersants available in Alaska (only 15 000L), the lack of boats, aeroplanes and helicopters and the lack of waves to mix the chemicals with the oil, this method was soon abandoned also. Boats resorted to sucking up weathered oil, and resigned themselves to unclogging their skimmers, as these were the most effective ways of removing the oil from the water.
It soon became apparent that with every 6 hour tide cycle, oil was washing from beach to beach and ruining the on-water cleanup efforts. Authorities quickly came to the decision that cleanups on shore were necessary. At first workers used fire hoses, which shot out highly pressurized hot water, cleaning the beach quite effectively. It was then considered that the hot water may be doing more harm than good, by killing small organisms in the water. A different method had to be adopted. The large deposits of oil near the low-tide line were tilled, mainly my machinery, and then flooded by hoses placed up above the high-tide level. The hoses had multiple holes along them, and sucked water from the sea, in turn releasing it to flood the oil. The oil then floated into the water, where it was caught by several layers of booms. It was then scooped up, sucked up or absorbed with special materials.
There have been multiple oil spills in and around Australia.