History Other / History Of Oil Spills In Australia
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Autor: anton 03 December 2010
Words: 873 | Pages: 4
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. Luckily, none of these have been extremely devastating, especially not to the extent of the Exxon Valdez tragedy. The first of these spills occurred in 1970, March 3rd. The tanker Oceanic Grandeur grounded in Torres Strait while carrying 55,000 tonnes of Sumatran (Indonesian) crude oil while bound for Brisbane. Estimates total at about 1,100 tonnes of oil spilt. Due to a very strong current, booms could not practically be used. It was decided that dispersants would be used, and worked quite effectively, with stronger chemicals being added closer to the tanker and less toxic chemicals to areas closer the shoreline. Miraculously, there was very little, if any, affect to the environment. A new legislation was passed however soon after, serving to arm Australia with proper oil spill response equipment.
The next major oil spill to occur in Australia requiring cleanup was the spill by the Al Qurain on the 28th of July 1989. An approximate 184 tonnes of oil escaped into a harbor when the tanker caught on a wharf knuckle. A boom was spread over the entrance of the harbor, and wind helped keep the oil in the south-east corner. Before equipment arrived, straw was used as an absorbent, but clogged up the retrieval devices used later (skimmers and vacuums). Polypropylene absorbents were then used with success. Later on high pressure water jet systems were brought in to clean the last of the oil. No environmental damage took place whatsoever.
Many other spills have occurred around Australia's coast since then. Some include the spills from the Nella Dan, Korean Star, Arthur Phillip, Sanko Harvest, Kirki, Era, Iron Baron, Mobil Refinery and Laura D'Amato.
The oysters are natural water filters. They ca filter up to 50L of water every day, and absorb the heavy metals and toxic wastes in the water such as cadmium, lead, chromium and pesticides, as well as things like copper and zinc which are needed in very minute amounts in organisms. Scientists can measure the amounts of heavy metal pollution in the water by measuring the amounts of heavy metals in the oysters.
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