Contamination of sea water due to an oil pour, as a result of an accident or human error is termed as oil spill. Oil is among the most important energy sources in the world and because of its uneven distribution, it is transported by ships across the oceans and by pipelines across the lands. This has resulted in several accidents in the past while transferring the oil to vessels, during transportation, breaking of pipelines, as well as while drilling in the earth’s crust. While massive and catastrophic spills receive most of the attention, smaller and chronic ones occur on a regular basis. These spills contaminate the coasts and estuaries and can cause serious health problems to human beings.
Oil is a mixture of hydrocarbon compounds, which are the decayed remains of marine animals and plants, died and drifted to the bottom. For the past 600 million years, under intense pressure and temperatures, these remains changed into complicated hydrocarbons called petroleum. Crude oil is a mixture of gas, naphtha, kerosene, light gas, and residuals, which causes hazardous health effects if consumed by any life forms.
It is estimated that approximately 706 million gallons of waste oil enter the ocean every year, with over half coming from land drainage and waste disposal; for example, from the improper disposal of used motor oil. Offshore drilling and production operations and oil spills or leaks from ships or tankers typically contribute less than 8 percent of the total. The remainder comes from routine maintenance of ships, hydro carbon particles from onshore air pollution.
How does oil impact marine life? Oil destroys the insulating ability of fur-bearing mammals, such as sea otters, and the water repellency of a bird's feathers, thus exposing these creatures to the harsh elements. Without the ability to repel water and insulate from the cold water, birds and mammals will die from hypothermia. Many birds and animals also ingest oil when they try to clean themselves, which can poison them. Fish and shellfish may not be exposed immediately, but can come into contact with oil if it is mixed into the water column. When exposed to oil, adult fish may experience reduced growth, enlarged livers, changes in heart and respiration rates, fin erosion, and reproduction impairment. Oil also adversely affects eggs and larval survival.
Oil Spills and the Shoreline
If oil waste reaches the shoreline or coast, it interacts with sediments such as beach sand and gravel, rocks and boulders, vegetation, and terrestrial habitats of both wildlife and humans, causing erosion as well as contamination . Waves, water currents, and wind move the oil onto shore with the surf and tide. Beach sand and gravel saturated with oil may be unable to protect and nurture normal vegetation and populations of the substrate biomass . Rocks and boulders coated with sticky residue interfere with recreational uses of the shoreline and can be toxic to coastal wildlife.
Oil spills present the potential for enormous harm to deep ocean and coastal fishing and fisheries. The immediate effects of toxic and smothering oil waste may be mass mortality and contamination of fish and other food species, but long-term ecological effects may be worse. Oil waste poisons the sensitive marine and coastal organic substrate, interrupting the food chain on which fish and sea creatures depend, and on which their reproductive success is based. Commercial fishing enterprises may be affected permanently. Wildlife other than fish and sea creatures, including mammals, reptiles, amphibians, and birds that live in or near the ocean, are also poisoned by oil waste. The hazards for wildlife include toxic effects of exposure or ingestion, injuries such as smothering and deterioration of thermal insulation, and damage to their reproductive systems and behaviors. Long-term ecological effects that contaminate or destroy the marine organic substrate and thereby interrupt the food chain are also harmful to the wildlife, so species populations may change or disappear. Coastal areas are usually thickly populated and attract many recreational activities and related facilities that have been developed for fishing, boating, snorkeling and scuba diving, swimming, nature parks and preserves, beaches, and other resident and tourist attractions. Oil waste that invades and pollutes these areas and negatively affects human activities can have devastating and long-term effects on the local economy and society.