Ocean Pollution Causes

Vijayalaxmi Kinhal
Water Polution

Wastes of all kinds have been dumped into the oceans instead of being treated or recycled. After decades of this policy, it is not surprising that ocean pollution levels have reached alarming proportions.

Oil Industry Contributions

The oil industry is responsible not only for the occasional large-scale oil spills, which prove catastrophic, but also for pollution that occurs on a regular basis. The National Oceanic Atmospheric Adminstration (NOAA) notes that natural oil seepage counts for a 45% of oil pollution in the ocean and is sometimes confused with human sources. However, 55% is caused by people.

  • Oil Spill
    Extraction of oil from the deep sea beds can cause 3% of the oil spillage. Accidents during production are a major factor here. The Deepwater Horizon Spill is one such example.
  • Transportation of oil by ships and pipes along with associated accidents and the malfunctioning that occur are responsible for 12% of oil pollution at sea. Sometimes a small crack in the pipe leaks many thousands of gallons of oil unnoticed under-water as was the case in the 2017 Louisiana oil spill.
  • Land-based activities are the major source of human oil spills, and account for 37% of it. This occurs when oil is used to make energy, or as fuels in vehicles. Leaks from cars and during repair all ultimately end up in the ocean. You may not realize it, but when you pour oil down the sink in your home, it can end up causing ocean pollution. Some people even intentionally dump oil into the ocean.

Industrial Dumping and Manufacturing

Land-based activities, like dumping, account for 80% of ocean pollution, points out National Oceanic and Atmospheric Administration (NOAA). Legal dumping was outlawed in 1972, by the international Marine Protection, Research, and Sanctuaries Act (MPRSA), which was also passed by the USA, according to EPA (Ocean Dumping). However, illegal dumping goes on as not all countries around the world enforce this Act strictly. Even though dumping is restricted, ocean currents move the old pollutants around the globe. In the USA by 1970, the materials dumped into the oceans were:

  • Dredged material - 38 million tons
  • Industrial waste - 4.5 million tons
  • Construction and demolition waste - 0.5 million tons

Nuclear Waste

Radioactive barrel in the ocean

MarineBio considers nuclear waste dumped into the sea a separate issue from other industrial dumping because of the hazards it poses, and because it remains active for decades. While some of these nuclear wastes are produced at sea by nuclear submarines reactors, most are land based nuclear wastes disposed off in the ocean. In the U.S., 55,000 containers of nuclear waste were dumped at three sites between 1946 to 1970.

Thermal Pollution

Water used for cooling during power production in coal and nuclear plants is released into the sea. Sometimes these liquids are warm and can raise the temperature of the ocean water, known as thermal pollution. Delicate ecosystems that cannot survive at higher temperatures may be wiped out entirely.

Acid Rain

A more subtle result of manufacturing is acid rain. Chemicals are released into the atmosphere and pollute the air, and when they are condensed acid rain is formed. The phenomena affects the coastal waters more than the open seas due to proximity to land and sources of pollution points out Woods Hole Oceanographic Institution.

Agriculture Causes

Farming and agriculture may seem far removed from ocean problems. Farmland is usually far inland and in landlocked places, such as the Midwestern United States. However, when it rains, chemical fertilizers and pesticides are washed into the rivers and streams that eventually flow into the ocean.

Nutrient Pollution

When the farm wastes enter local water bodies and oceans, chemicals nitrogen and phosphorus are added, causing nutrient pollution says the EPA. The addition of these chemicals acts as a fertilizers helping "overgrowth of algae". They consume all the available oxygen in the water, so other plant and animal life die. In coastal areas, this creates vast dead zones.

The largest dead zone off the U.S. coast in the Gulf of Mexico measured 8776 square miles in the summer of 2017. Nitrogen and phosphorus are found in high concentrations in fertilizers, from farm and gardens, but are also present in detergents and soaps from homes, and run-off that carries gases released through burning fossil fuels in vehicles and factories.

Litter and Trash

Few things can dampen the mood of your romantic sunset walk on the beach more than seeing a plastic bottle wash up onto shore. Of all the materials littered in the oceans, plastic is the major pollutant and accounts for 70% of the garbage. This litter could come from many sources.

Land Sources

This can happen due to littering on land and when the trash reaches oceans by entering streams and rivers. Ninety percent of plastic wastes are discharged by 10 long rivers flowing through some densely populated areas in Asia and Africa. Plastic, like plastic bags, is especially dangerous to marine life because it disintegrates into tiny pieces and is often ingested.


At times people litter the beaches, or the litter washes up on beaches from the oceans. Ocean Conservancy conducted beach clean-ups around the world, and reported that the ten most collected objects were cigarette butts, plastic beverage bottles, bottle caps, food wrappers, plastic grocery bags, plastic lids, plastic straws, glass beverage bottles, plastic bags and foam food containers (pg. 15).


Ships dump their trash while out at sea. Twenty percent of the pollution comes from sea, writes Ocean Health Index, including trash. Though ocean liners make up only 1% of the ships, they produce 25% of the waste from ships. This is domestic, cooking, operational, and sewage wastes. Although it is generally banned in the U.S., many third world countries dump their local trash directly into the ocean, either along the shore or by ship.

Sewage Pollution

Although it's hard to imagine raw sewage being dumped into the ocean, it happens on a regular basis. The oceans are vast and can break down this vile liquid, but it still causes many adverse effects on marine life.

  • Sewage discharge
    Sewage: Sewage includes "black water" from toilets and also water from laundry, food preparation and sinks, referred to as "gray water". Many times the sewage is discharged into the sea without being treated. Every year, 3 to 10 billion tons of untreated sewage waste from the U.S. ends up in rivers and from there into oceans.
  • Chemicals: Besides the sewage, there are also the toxic cleaning products and other household substances that are flushed down the sink finding their way into the ocean. Sometimes, sludge from sewage treatment is also dumped into the ocean. Consider what happens when it rains and all the grime from the streets is washed into the sewer system, which could eventually wash out to sea. This also contributes to nutrient pollution.

Fortunately, sewage dumping has dropped from 18 million tons in 1980, to 12 million tons in the 1990s, due to MPRSA according to MarineBio.

Mining at Sea

Mining for rare metals like copper, cobalt, gold, silver, nickel, platinum occurs in oceans from reserves deep under the ocean beds or from the ocean bed surface according to Phys.org. Oceans cover around 70% of the earth surface and therefore have more mineral resources than on land. Ocean mining causes many problems.

  • The main concern is the plumes of dust particle and toxic chemicals that are released during mining.
  • The mining operation is a source of light and noise pollution that disrupts marine life.

Deep sea mining is a relatively new threat to the ocean, and can be more disastrous than mining on land for the ecosystems and its associated flora and fauna according to Huffington Post.

Causes of Oceanic Noise Pollution

Another form of oceanic pollution that is receiving attention is noise pollution.

  • Shipping and seismic surveys with air guns for natural resource exploration can be very loud.
  • Man-made noise is also disrupting natural channels of communication among animals, points out Scientific American.

Besides these acute sources of noise, long -term exposure to low levels of sound can stress marine animals just as it does humans.

Ocean Pollution Eventually Affects Everyone

It may not seem like pollution that exists in the middle of the ocean would have much of an effect an individual's life, but it will all eventually wash up onto shore or fall as rain through the process of evaporation and condensation. People who love animals, enjoy seafood, or like to take trips to the beach should understand ocean pollution causes, and even more importantly, become part of the solution.

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Ocean Pollution Causes