Crude oil pollution of the sea, coastal waters and shores is becoming more common nowadays. The main cause is spillage from oil tankers, offshore oil wells and the various sea going vessels. In the recent oil spillage disaster in 1989, the supertanker Exxon Valdez struck a reef, pouring 50 million litres of crude oil into the waters of prince William sound, Alaska. Innumerable life forms perished, and despite rescue efforts, more than 100,000 birds and 1000 sea otters died. Oil drenched about 20,000 kilometers of shoreline. Cleaning up and rehabilitation programmes cost over a thousand million dollars.
When oil spillage occurs, the crude oil floats on waters and spreads. The volatile components soon evaporate, leaving a viscous oil slick. Wave action causes the oil slick to form a sticky heavy emulsion. Further, wind, wave and bacteria action break up and slick into smaller portions that may become washed ashore.
Crude oil is toxic, affecting the lungs, liver and kidneys in animals. Oil covered animals usually suffocate. Oiled birds often cannot fly to their feeding and nesting grounds. The feathers also loose their insulating property. In addition , the birds poison themselves by trying to clean their feathers. Many oil covered birds reach their nests and contaminate their young and eggs.
Generally, a large oil spillage devastates the ecosystem in the area and poisons the various habitats for years. Fish and bird population are often badly damaged. Beaches become unusable until they are cleaned up. Fishermen in the area are badly affected as the fished, their sources of income , are destroyed.
Cleaning up oil spills is extremely expensive. Chemical dispersants are sprayed in the oil mass to break it up into tiny droplets that mix with water. Skimmers using adsorbents and pumps collect the oil From These waters. The oil on beaches is washed to the waters edge with high pressured water sprays and mopped up or collected by skimmers. Many ecologist feel that these efforts end up by destroying more marine life, especially those in the tidal and intertidal zones.
Oil eating bacteria are also used to clean spilled oils. In the Alaskan disaster, oil covered beaches were sprayed with a special nitrogen phosphorus fertilizer that stimulated the growth of the normally occurring oil eating bacteria in the environment. This method was found to be quite effective in cleaning up the oil mess on the beaches.
