Components Of Crude Oil example essay topic

Pollution People have long used the sea as a dump for our wastes. Most of the pollution dumped into the ocean comes from human activities on land. Marine pollution is defined as the introduction into the ocean by humans of substance or energy that changes the quality of the water or affects the physical, chemical, or biological environment. There are different types of pollution. One of them is natural pollutants. An example would be a volcanic eruption which can produce immense quantities of carbon dioxide, methane, sulfur compounds, and oxides of nitrogen.

Excess amounts of these substances produced by human activity may cause global warming and acid rain. No one is sure to what extent we have contaminated the ocean. By the time the first oceanographers began widespread testing, the Industrial Revolution was well underway and changes had already occurred. Traces of synthetic compounds have now found their way into every oceanic corner. Pollutants cause damage by interfering directly or indirectly with the biochemical processes of an organism.

Some pollution-induced changes may be instantly lethal; other changes may weaken an organism over weeks or months, alter the dynamics of the population of which it is a part, or gradually unbalance the entire community. Oil is a natural part of the marine environment. Oil seeps have been leaking large quantities of oil into the ocean for millions of years. The amount of oil entering the ocean has increased greatly in recent years, however, because of our growing dependence on marine transportation for petroleum products, offshore drilling, near shore refining, and street runoff carrying waste oil from automobiles. Oil reaches the ocean in runoff from streets or as waste oil poured down drains, into dirt, in trash destined for a landfill. Every year more than 908 million liters of used motor oil finds its way into the ocean.

Motor oil that has been used is more toxic than crude oil or new oil because it has developed carcinogenic and metallic components from the heat and pressure within internal combustion engines. Spills of crude oil are generally larger in volume and more frequent than spills of refined oil. Most components of crude oil do not dissolve easily in water, but those that do can harm the delicate juvenile forms of marine organisms even in minute concentrations. The remaining insoluble components from sticky layers on the surface that prevent free diffusion of gases, clog adult organisms feeding structures, kill larvae, and decrease the sunlight available for photosynthesis. Another type of pollution in the ocean is sewage. 98% of sewage is water.

Sewage treatment separates the fluid component from the solids, treats the water to kill disease organisms and reduce the levels of nutrients, and release it into an ocean or a river. What remains is called sewage sludge, which is a semisolid mixture of organic matter containing bacteria and viruses, toxic metal compounds, synthetic organic chemicals, and other debris. It is digested, thickened, dried, and shipped to landfills, burned to generate electricity, or dumped into the ocean. The liquid effluent wanders from its outlet and circulates with currents, but sludge and other insoluble residues may stay near the outfall or dump site for years. The amount of wastewater and sewage sludge increased by 60% in the 1990's. Until 1992 almost 2 billion liters of partially treated sewage poured into Boston Harbor every day.

A new sewage treatment plant opened in that year, 22 years after the deadline mandated by the US Clean Water Act. About the same amount of treated sewage pours from outfall pipes extending about 5 miles out to sea from the coast at Los Angeles. Treatment plants in southern California are sometimes overwhelmed after heavy rainstorms, and raw sewage enters the ocean in large quantity. Rain or shine, area around San Diego Harbor are often so contaminated with sewage from the city of Tijuana, Mexico, that anyone who enters the water runs the risk of bacterial or viral infection. Electrical generating plants use seawater to cool and condense steam.

The seawater is returned to the ocean about 6 degrees Celsius warmer, differences that overstress marine organisms in the effluent area. Some recent power plant designs minimize environmental impact by pumping colder water from further offshore, warming it to the temperature of the seawater surrounding the plant site, and then releasing it. This method minimizes the impact on the surrounding communities, but it still shocks those eggs, large, plankton, and other organisms that are sucked through the power plant with the cooling water.