Pollution

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.