What Causes Ocean Pollution?

By Salome Chelangat on May 23 2018 in Environment

Plastic seen floating in the ocean.
Plastic seen floating in the ocean.

What Causes Ocean Pollution?

Pollution is defined as the process of introducing harmful or poisonous substances into the natural environment. Ocean pollution is therefore defined as the introduction of toxic materials such as plastic, oil, chemicals, agricultural waste, and industrial waste into the ocean waters. There can be several causes of ocean pollution, but the leading causes include sewage, toxic chemicals from industries, nuclear waste, thermal pollution, plastics, acid rain, and oil spillage.


Sewage is defined as the wastewater and its component excrements that are transported in the sewer system. Sewage is mostly comprised of the human waste from toilet flushing, dirty water from bathing and even animal waste. Most of the wastes find their way into the ocean waters through the sewer systems. Some of the substances that are in the sewage waste are harmful and contribute greatly to ocean pollution. These substances may cause serious health problems to the aquatic creatures once they consume them.

Industrial Chemicals

Another major pollutant is the chemicals from industries and from the fertilizers and other farm products that are carried by run-off water into the ocean waters. Many industries dump their waste materials and chemicals into the ocean waters. These chemicals pollute the ocean by altering the pH level of the waters. Most aquatic plants and animals cannot survive in adverse pH levels.

Nuclear Waste

Another major ocean pollutant is the nuclear waste, which is mostly produced from industrial, medical, and also scientific procedures that use radioactive material. The common industries that produce nuclear waste include power stations, the military, and the reprocessing plants. This radiation enters the food chain through kelp and plankton, and once the marine animals consume these plants they become contaminated.

Thermal Pollution

Thermal pollution is the lowering of water quality by any method that tends to change the water temperature. Thermal pollution occurs when power plants and manufacturing companies release hot water into the water streams and oceans and thus causing a change in temperature by raising the temperatures higher. The sudden change in temperature causes reduction in the oxygen supply and this greatly affects the ecosystem composition. Aquatic plants and other organisms that are adapted to a certain temperature range get killed abruptly by the sudden change in temperature by a process known as thermal shock.


Plastic pollution mainly involves the accumulation plastic in the ocean waters and thus causing adverse effects on marine organisms. Marine organisms are affected by the plastics through direct ingestion of the plastic wastes and also through exposure to chemicals that are within the plastics.

Acid Rain

Acid rain is not a major cause of ocean pollution, but it also contributes to water pollution. Erupting volcanoes, fossil fuels, rotting vegetation, and nitrogen oxides when released into the atmosphere react with water and other substances in the air to form sulphuric and nitric acid. The wind blows these chemicals across the atmosphere, and when it rains, these chemicals find their way into the marine waters. Acid rain makes water acidic and thus destroys the marine life as most aquatic organisms cannot survive in acidic conditions.

Oil Spills

Oil spillage is another primary cause of ocean pollution in that the oil forms a layer on the water preventing oxygen circulation. Lack of oxygen in the ocean waters results in the destruction of marine life over a long period. Therefore, it is necessary to prevent these pollutants from entering the oceans to protect the marine animals and plants.

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