Marine Pollution or Ocean Pollution

What is Marine or Ocean Pollution?

Marine pollution, ocean pollution or sea pollution is said to occur when toxic & harmful substances, debris, garbage or trash enters ocean or sea. Marine pollution is now a matter of concern all around the globe. The pollution is growing vigorously without any measure to prevent it and disturbing the marine ecosystem. Harmful chemicals and trash are the two main reasons that are spreading marine pollution at an unbelievable rate. Statistics show that 80% of the pollution is derived from the land. Industrial and residential waste, floating plastic, windblown debris and agricultural runoff are some of the other reasons for marine pollution. Marine pollution is often confused and mixed with other similar terms. Marine pollution, ocean pollution, sea pollution all are of similar kind and these terms are used interchangeably. Broadly all of these can be clubbed under water pollution.

Oceans are the most valuable resources of the Earth that cover almost 70% of the planet. The oceans rule the weather, nourish the world, maintain the ecosystem, purify the air and supports aquatic life. The ocean is the home of many marine mammals, animals starting from microscopic algae, small fishes to the blue whale. Yet the oceans are bombarded with pollution almost every day. All the waste and harmful chemicals enter the river which leads to the sea. So they are the ultimate endpoint of dumping of pollution that we produce on land.

Dangerous emissions of carbon, leakage of oil, constant noise, and plastic are some of the pollutants that are dominating the waters of the sea. As a result of pollution, the health of the sea is degrading at an unbelievable rate. Some of the plastic waste that we dump ends up on the beaches across the globe while some are eaten by the animals by mistaking them as their food.

Marine Pollution - Ocean Pollution

The lethal metals that are discharged into the water are consumed by animals. And therefore, there is a huge change in their tissues, reproduction, behaviour, biochemistry, and growth due to metal consumption. In this article, we are going to discuss the causes and effects of marine pollution, and policies or laws that have been surpassed to prevent it.

Related: Types of Pollution, Environmental Education, Importance of environmental education

Different Types of Marine Pollution

Some of the most common types of marine pollution are:

  1. Eutrophication
  2. Acidification
  3. Toxins
  4. Plastic Pollution


Eutrophication is the increase in the chemical compounds in the ecosystem due to the presence of excessive phosphorus and nitrogen. Rivers containing fertilizers, human and livestock wastes, chemicals, and many harmful elements dump themselves into the ocean. This results in the creation of hypoxia and dead zone.

The southern coast of the US, East Asia, West Europe, and Japan- all these areas are identified with 375 hypoxic zones. Due to eutrophication, there is a huge production of algae that consumes all the oxygen of the surface, resulting in the death of mammals and fish in the ocean.

According to a study in 2008, it has been found that the accumulation of reactive nitrogen in the ocean is more dangerous than the accretion of Carbon Dioxide in the environment.

The only solution for eutrophication is to refurbish the population of oysters and shellfish in the sea. Oysters consume algae, reduces the level of nitrogen and filter out all the solids present in the water. Shellfish enhance the water quality by reducing all the phytoplankton lost due to denitrification.


The ocean absorbs carbon dioxide from the environment. Due to an increasing level of this carbon dioxide, oceans are becoming highly acidic. This is a cause of concern as the structures like corals that are made up of calcium carbonate will get dissolved and will affect the capability to form shells by the fish.

Sea absorbs almost 25% of the global carbon dioxide level and half the release of anthropogenic carbon. Rising ocean acidification will weaken the ability to sink carbon giving rise to more global warming.

Another reason for marine acidification is methane clathrate which will be released due to excessive ocean temperature. In 2004, almost one and five million cubic km of the ocean floor are covered with this gas. This number is equal to 500 to 2500 Gt carbon. Now you can imagine where this is going.


Innumerable toxins like PCBs, TBT, DDT, heavy metals, radioactive wastes, dioxins, furans, and pesticides do not disintegrate speedily in the ocean. These toxins mount up inside the tissues of many aquatic animals through a process called bioaccumulation. Bioaccumulation results in many deformations and unnatural death of the organisms.

Plastic Pollution

Plastics are gathering in the ocean since the end of World War II and now contain 80% of the ocean debris. It is estimated that the total mass of the plastic present in the entire marine world is nearly about 100,000,000 tonnes!

Anything made of plastic, especially plastic bag can entangle oceanic creatures, restricting the movement, causing starvation, suffocation, infection and ultimately resulting in a painful death. Debris of plastics tends to gather at the center of the ocean. The north pacific gyre has collected so much plastic that the zone is almost 21 times the size of Texas City.

Additives used in plastic materials are more deadly in the ocean than the land. They enter the body of the organisms and disrupt the endocrine system. It can also suppress the reproduction and immune system of the body.

Microplastics are also equally harmful as plastics. Due to their small size of less than 5 mm, they are mainly used in face scrubs, cleansers and hand soaps. The microbeads are harmful to filter feeders as they can swallow this plastic and become sick.

Different causes of Ocean & Marine Pollution 

In several ways, the input sources of marine pollution into the ecosystem can be identified.  Point source pollution and other major source of pollution are explained below. There are various types of inputs for the pollution and some of these are:

  1. Direct Discharge of waste
  2. Land Runoff or surface runoff
  3. Pollution by ship
  4. Pollution through atmosphere
  5. Pollution due to mining in the deep sea
  6. Acidification of the oceans
  7. Underwater noise
  8. Trash and debris in the ocean
  9. Offshore mining

Direct Discharge of Waste 

Industrial chemicals are discharged from the urban sewage into the rivers which in turn get submitted to the sea. It can be in the form of plastics or hazardous chemicals. China, Indonesia, Sri Lanka, Egypt, Nigeria, the Philippines, Vietnam, Thailand, Malaysia, and Bangladesh are the major emitters of plastic waste into the ocean.

Mining of different metals like gold, copper, coal, etc is another cause of marine pollution. Minerals like copper, when get mixed in the water, can alter the life development of coral polyps. According to a report by USEPA, 40% of the water bodies in the western USA are contaminated due to mining.

Land Runoff

Runoff due to the construction of buildings and infrastructure carries particles laden with nitrogen, phosphorus, heavy metals, carbon, petroleum, and minerals. When the runoffs are eliminated in the water, it gives birth to phytoplankton and algal blooms. These algae use up all the oxygen (a situation called hypoxic) leading to the death of fish, dolphins, and turtles.

Pollution by Ship

Oil spills by ships are one of the major reasons for marine pollution globally. Crude oil contains PAH (Polycyclic Aromatic Hydrocarbons) is very difficult to remove and remain in the marine environment for years.

Tankers discharging oil tank’s ballast water, disposal of engine oil from the down sewers, and leaking pipelines are the chief poignant of marine pollution. Sometimes cargo ships intentionally discharge harmful and illegal chemical wastes into the ocean in spite of violation of foreign and domestic regulations.

According to statistics, almost 10000 containers are lost during storms under the sea causing noise pollution and multiplication of harmful algae and invasive species.

Pollution through the Atmosphere

Plastics bag and dust are blown by the atmosphere into the sea. Dust from different desserts like Sahara, Gobi, and the Taklamakan is blown towards the Atlantic and the Pacific Ocean.

However, nowadays, global warming is raising the temperature of the atmosphere due to which carbon dioxide levels are also increasing. High levels of CO2 are making the oceans acidic in nature. As a result of this, the marine ecosystem is getting disturbed

Pollution Due to Mining in the Deep Sea

This is the recent mineral retrieval process from the bottom of the ocean floor. It generally takes place around polymetallic nodules or extinct and active hydrothermal vents. These types of vents are present around 1400 to 3700 meters beneath the surface of the sea. Precious metals like manganese, gold, copper, silver, and zinc are mined through the vents by the use of hydraulic pumps and are brought to the surface.

Acidification of the Ocean

When a fossil is burnt, not only the surrounding air is polluted but oceans get contaminated too. Right now the sea is absorbing a quarter portion of all carbon emissions created by the human race. This is generating a change in the pH balance of the water and thus leading to acidification of the ocean. The oceans are now acidifying at a much faster rate than the past 300 million years.

According to a study it is estimated that by the end of the year 2060 if we continue to emit our current percentage of carbon, then ocean waters will be 150 times more acidic than it is right now. This will affect many marine animals like shellfish, coral, clams, oysters, and mussels. These types of animals need calcium carbonate to produce their skeletons and shells. But when the acidic level rises due to a low carbonate level, a threat is posed to the life of these marine life and coral reefs.

According to Manado and Monaco Declarations, many pressing global concerns will rise due to increasing temperatures and acidification of the ocean, resulting in the weak ocean carbon sink. Also, a report of NOAA scientists shows that 4 miles of the continental shelf area of the Pacific in North America has a large portion of acidic water. This is the most critical zone of the Pacific as most of the marine animals are born or lives here.

Underwater Noise

Sound waves in the water travel much faster in water than in the air. Many animals like dolphins, cetaceans, and whales rely on sound to mate, navigate or find their food. But due to a mounting bombardment of noise pollution in the ocean, the undersea acoustic setting is altered and killing many species.

Between 1950 and 1975, the noise intensity at one point in the Pacific Ocean is enhanced by ten decibels that are tenfold increase in the intensity. Loud noise forces the animals to communicate louder than the normal tone, a condition called Lombard Vocal Response. Sometimes their voices are hidden by anthropogenic sounds. These unheard voices might be a sign of warnings, net bubbling or suffocation. The loud vibration under the sea destroys the cilia hairs of Coelenterates. Moreover, damaged hair cells, missing bent, missing stereocilia, and kinocilia are some of the harmful effects when marine animals are exposed to high sound waves.

Trash Debris in the Ocean

The major source of marine pollution is the plastic pollution. Grocery bags, plastic bags, drinking straws, containers for food, perfumes, medicines, and water bottles made of plastic will stay in the atmosphere for millions of years. According to research, almost 8 million metric tons of plastic will not biodegrade for the next 400 years. Instead, they will remain in the environment polluting the beaches, entangling and affecting marine organisms.

It is estimated that almost 80% of the plastic litter in the ocean are from the land carried to the sea through sewers, drains or via natural calamities. Turtles consume plastics that look like a jellyfish when submerged in water. They have a system in their body which can prevent any slippery food to escape. When plastic enters the throat of the turtles, it will block the passage resulting in either infection or starvation.

Also oil from the ships, toxic chemical discharges from factories, sewage overflow from the systems of water treatment plants, agricultural runoffs and some of the reasons for marine toxin pollutants.

Offshore Mining

Oil and Gas industry are constantly drilling the bed of the seafloor, thus emitting high levels of toxic by-products, greenhouse gases, and thousand liters of spills. In 2010, 1.8 million gallons of toxins are released into the Gulf of Mexico by BP Deepwater Horizon. This oil remains as it is till date without any measure to remove it from the ocean surface.

Rules and Regulations to Control Marine Pollution

The following Acts and Regulations are passed to control marine pollution all over the world.

  • Federal Water Pollution Act was signed in 1948 to control marine pollution in the USA
  • The Council on Environmental Quality has passed the Marine Protection, Research, and Sanctuaries Act in 1972 to control dumping into the ocean
  • In the year 1973 and 1978, a treaty called MARPOL 73/78 was signed to manage pollution by the oil vessels
  • In 1982, UNCLOS was founded to control and restrict the number of pollutants and toxins from all the ships that come internationally
  • United Nation’s 14 Goal – Life Below Water focuses on reducing the marine pollution (United Nations)

People are becoming more aware of global warming and doing their part to reduce it. Many countries are now focusing on public awareness and taking action to reduce the use of plastics. In 2018, a report by the United Nations shows that more than 65 countries across the world have banned the use of plastic items. However, it is every person’s responsibility to maintain the basic cleanliness and not to pollute the environment. It is ‘we ourselves’ who can bring this change to the environment and get the marine pollution stopped.

Some facts and figures about marine pollution

  1. Oceans cover over 75% of the Earth surface. They are home to over 99% of the living space on the planet by volume.
  2. Oceans remains unexplored to a great extent. They contain nearly 0.2 million identified species but actual figures might be much more.
  3. Over 40% of the oceans are affected due to pollution, reduced fisheries, loss of coastal habitats. Most of the reasons for such large loss remains human activities.
  4. Oceans not only supports large number of species but also absorbs as much as 30% of the carbon dioxide produced by human activities.
  5. More than 3 billion people depend directly or indirectly on oceans. Market value of marine and coastal resources is over 3 trillion USD.
  6. Only 12 % of oil is spilled by the ships into the ocean. Almost 3 times more oil is dumped into the sea every year from the road, drainage pipe, and river runoffs.
  7. There is a total of 5 garbage patches in the ocean around the world. The largest of them is the Great Pacific Garbage Patch which contains 1.8 trillion trash and covers twice the area of Texas City.
  8. 70% of the garbage sinks to the bottom of the seafloor which we are unable to clean
  9. According to research by scientists, 146 hypoxia low oxygen zones are present in 2004. In 2017, a dead zone nearly the size of New Jersey was detected in the Gulf of Mexico.
  10. Noise pollution is damaging the cells of invertebrates like jellyfish and anemones. These are a vital source of food for sharks, tuna, and sea turtles.
  11. Every year we dump 8 million metric tons of plastic into the ocean. By 2050, if this rate of dumping of plastic continues, then plastic will outweigh all the fish inside the oceans.

The fate of the oceans depends upon us and the governments. We believe the daily activities of every individual will help in the degradation of sea pollution. Reduction in the home runoff, no use of plastic or cleaning up of the nearest waterway will slow down ocean pollution.

Related: Strategic Environmental Assessment (SEA), environmental degradation, Environmental Sustainability, Sustainable Development Goals

Tags: Marine Pollution, Water Pollution, Ocean Pollution, Sea Pollution, Plastic Pollution, Aquatic life, aquatic pollution, Marine pollution Facts, Aquatic life, underwater pollution