How Oceans Act As Natural Pollution Filters

Oceans are a vital natural resource, covering more than 70% of the Earth's surface and performing essential functions like regulating the weather, cleaning the air, and providing sustenance and livelihoods for millions of people. Unfortunately, human activities have led to the degradation of ocean health, primarily through pollution. The majority of marine pollution originates from land-based sources, including runoff from farms, sewage, and industrial waste, as well as direct dumping of trash and chemicals. Plastic pollution is a significant concern, with single-use plastic items like bags, bottles, and packaging making up a large proportion of marine debris. In addition to the physical hazards of plastic waste, the oceans also absorb carbon emissions from human activities, leading to increased acidification and changes in water chemistry that threaten marine life and human health.

Plastic pollution

The ocean, covering more than 70% of the Earth, is among the most valuable natural resources. It is home to most of the life on Earth, from microscopic algae to the blue whale, the largest animal on the planet. However, human activities have led to the ocean being bombarded with pollution. Plastic pollution is a pressing environmental challenge of our time, impacting the health of the ocean and its ecosystems.

Microplastics are a significant part of the marine plastic pollution problem because they can mimic fish eggs and other tiny organisms, leading to consumption by sea life. Once microplastics reach the ocean, they are nearly impossible to filter out without causing significant damage to marine life, so they become a permanent feature of the ecosystem. Plastic debris in the ocean also accumulates pollutants and transports them through ocean currents. Research shows that marine life that ingests plastics coated with pollutants can absorb these pollutants into their bodies.

The majority of marine debris (80%) comes from land-based sources, including trash and debris from construction, ports, marinas, commercial and industrial facilities, and trash blown out of garbage containers, trucks, and landfills. The remaining 20% comes from ocean-based sources, such as overboard discharges from ships and discarded fishing gear. Food containers and packaging are the largest components of municipal solid waste.

Addressing plastic pollution is crucial to safeguarding ecosystems and preserving biodiversity. It also helps prevent the proliferation of microplastics through the food chain, protecting human health. While recycling may not be an economically viable option for all plastic waste, reducing the use of plastic packaging and disposable products can help mitigate plastic pollution. Governments and industries must work together to implement large-scale, systemic changes to tackle this global issue effectively.

Nutrient pollution

Nitrogen and phosphorus enter the oceans through various human activities, including agriculture, aquaculture, and atmospheric nutrient deposition. Agricultural fertilisers, human sewage, and farm animal manure are significant sources of these nutrients. Burning fossil fuels, such as in car engines, also releases nitrogen-containing compounds into the atmosphere, which eventually find their way into the sea. Industrial operations, transportation, and coal power plants are additional contributors to nitrogen pollution.

The impact of nutrient pollution is exacerbated by other human activities, such as climate change, overfishing, and ocean acidification. Climate change increases river runoff, leading to higher levels of nutrient pollution. Overfishing reduces the number of algae-eating organisms, allowing algal blooms to grow larger. Ocean acidification, caused by the ocean's absorption of carbon dioxide, further stresses marine life.

To address nutrient pollution, it is crucial to reduce nutrient inputs into coastal marine ecosystems. This involves implementing regulations and incentives to decrease agricultural pollution, as well as restoring habitats like mangroves and marshes that can act as natural filters. Additionally, better monitoring of nutrient pollution on a global scale is necessary, along with the development of integrated solutions that involve ecosystem management.

The consequences of nutrient pollution are severe, with over one-third of shellfish-growing waters in the United States adversely affected. It poses a threat to the shellfish industry, which is vulnerable to ocean acidification and nutrient pollution, and can result in economic losses for coastal communities.

Nonpoint source pollution

Oceans are the endpoint for much of the pollution produced on land, whether from sources near the coast or far inland. One of the biggest sources of ocean pollution is nonpoint source pollution, which occurs as a result of runoff. Nonpoint source pollution is defined as any source of water pollution that does not meet the legal definition of "point source" in the Clean Water Act. Point sources refer to confined conveyances or discrete sources from which pollutants are discharged, such as pipes, ditches, tunnels, or vessels.

The effects of nonpoint source pollution are significant and can render river and ocean water unsafe for both humans and wildlife. It can lead to beach closures after rainstorms and negatively impact shellfish-growing waters, with over one-third of these waters in the United States affected by coastal pollution. Nonpoint source pollutants can cause water to become cloudy, hindering aquatic organisms' ability to see and feed properly. It can also damage fish gills and the breathing of aquatic insects, as well as reduce sunlight penetration, affecting plant growth. Additionally, sediments carried by nonpoint source runoff can contain metals and toxic chemicals, further degrading water quality.

Addressing nonpoint source pollution is a complex and costly endeavour. Agencies like the National Oceanic and Atmospheric Administration (NOAA) work with federal and state partners to monitor, assess, and limit this type of pollution. Efforts include developing nonpoint source pollution control plans for coastal states and implementing programs to address and mitigate the impacts of nonpoint source pollution on aquatic ecosystems.

Oil spills

Large oil spills are major environmental disasters that can have long-lasting impacts. They tend to happen when pipelines break, big oil tanker ships sink, or drilling operations go wrong. Oil spills can also occur during the transportation of oil by ship or pipeline to a refinery, or when removing crude oil from underground. Accidents involving tankers, barges, pipelines, refineries, drilling rigs, and storage facilities are the most common causes of oil spills. Even recreational boats can release oil into the water or in marinas.

When oil spills into the ocean, it can harm sea creatures, make seafood unsafe to eat, and ruin beaches. Oil spills can affect plants and animals in two main ways: fouling or oiling, and oil toxicity. Fouling or oiling occurs when oil physically harms a plant or animal. For example, oil can coat a bird's wings and leave it unable to fly, or it can strip away the insulating properties of a sea otter's fur, putting it at risk of hypothermia. The degree of oiling often impacts the survival chances of the affected animal.

Oil is also toxic and contains many different compounds that can cause severe health problems in marine life, including heart damage, stunted growth, immune system effects, and even death. The impact of an oil spill depends on its timing, duration, and the number and types of organisms affected. Large spills in the deep ocean with little bird life may have less effect on seabirds than smaller spills in critical habitats with high numbers of birds. Additionally, spills that occur during breeding or migration seasons will have a greater impact on bird populations.

Chemical contamination

Oceans are a sink for chemical pollutants, and these contaminants will remain in the oceans for years or even centuries. Oceans absorb about a quarter of all man-made carbon emissions, which increases the pH of surface waters, leading to acidification. This problem is worsening, with oceans acidifying faster than they have in 300 million years.

Nonpoint source pollution, resulting from runoff, is a significant contributor to ocean chemical contamination. It can originate from septic tanks, vehicles, farms, livestock ranches, and timber harvest areas. This type of pollution can make river and ocean water unsafe for humans and wildlife, leading to beach closures after rainstorms. Point source pollution, on the other hand, comes from a single source, such as an oil or chemical spill, and while it occurs less frequently, it can have a substantial impact.

The oceans are also contaminated with pesticides such as DDT, which has been banned or restricted in most developed nations due to its detrimental effects on the environment and human health. However, its unregulated use in underdeveloped countries continues to contaminate marine waters. Additionally, perfluoroalkyl substances (PFAS), used in manufacturing non-stick cookware, stain-repellent carpets, water-repellent clothing, and firefighting foam, have caused extensive contamination of surface waters and groundwater. PFAS compounds have entered the oceans in substantial quantities and are now part of the marine food chain.

The impact of chemical contamination on marine life and human health is significant. Microplastics and nanoplastics containing manufactured chemicals can enter the tissues of marine organisms, including seafood consumed by humans. Pollutants such as methylmercury and PCBs have been linked to adverse health effects in infants, including brain damage, reduced IQ, and increased risks for autism and learning disorders. Sun cream contamination is also an emerging concern, especially for sensitive habitats such as coral reef systems.

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