Brian Barton
Marine pollution is a pressing issue that poses a threat to marine wildlife, ecosystems, and human health. It refers to the introduction of harmful substances, such as chemicals and trash, into the ocean and coastal areas. These pollutants come from a range of sources, including land-based activities, marine transportation, atmospheric deposition, and ocean mining. The accumulation of marine debris, such as plastic pollution, nutrient runoff, toxins, and noise pollution, has detrimental effects on marine life and ecosystems. The consequences of marine pollution are far-reaching, impacting the environment, human health, and economic structures worldwide. With the majority of pollution originating from human activities, addressing this issue requires a combination of preventative measures, improved waste management, and global efforts to reduce the use of single-use plastics and disposable items.
| Characteristics | Values |
|---|---|
| Definition | "The introduction by man, directly or indirectly, of substances or energy into the marine environment … which results or is likely to result in such deleterious effects as harm to living resources and marine life." (UNCLOS, 1982) |
| Types | Marine debris, plastic pollution (including microplastics), ocean acidification, nutrient pollution, toxins, underwater noise, chemical pollution, sewage, urban and industrial runoff, atmospheric pollution |
| Sources | Land-based activity (80%), marine transportation, air pollution, inland mining, oil spills, ships, ballast, bilge, fuel tanks, nonpoint source pollution (e.g. cars, boats, farms, construction), point source pollution (e.g. oil spills, chemical spills, faulty factories, water treatment systems), agricultural runoff, urban wastewater, industrial discharge, sewage discharge, urbanization, land use |
| Effects | Harm to marine life and ecosystems, negative health outcomes in humans, economic impacts on industries and livelihoods (e.g. fisheries, tourism), oxygen depletion leading to dead zones, endocrine disruption, reduced reproduction rates, impact on coral health |
| Solutions | Prevention (e.g. reducing plastic use, choosing organic fertilizers), cleanup (although challenging for some items), regulations and bans on disposable plastic items |
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What You'll Learn
Marine debris
The majority of marine debris is plastic, which accounts for around 80% of all marine debris. Plastic is particularly problematic as a pollutant because it does not easily biodegrade and can persist in the environment for hundreds of years. Some materials, such as biodegradable plastics, may only break down under specific conditions not found in the ocean. As a result, plastics tend to accumulate in the ocean, collecting in large "patches" in ocean gyres, or swirling ocean currents. These patches are made up of flecks of microplastic that pepper the ocean surface and below.
Common types of plastic marine debris include plastic bags, bottles, food wrappers, balloons, cigarette butts, bottle caps, polystyrene, and fishing gear such as nets and lines. These items can be harmful to marine life, as animals can become tangled or injured by the debris, or mistake it for food. Small organisms may ingest microplastics, absorbing the chemicals into their tissues. These toxins can then move up the food chain, eventually reaching humans through seafood consumption, leading to potential health issues.
Efforts to address marine debris include prevention and cleanup initiatives. The NOAA Marine Debris Program in the US, for example, supports projects that raise awareness, prevent debris from entering the ocean, and remove existing debris from shorelines and coastal areas. Internationally, laws and policies have been adopted to reduce marine pollution, and countries have enacted regulations to limit or ban disposable plastic items.
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Plastic pollution
Marine plastic pollution is a severe and growing problem, with plastic accounting for 80% of marine debris. It is caused by both land-based and sea-based activities, with the former being the dominant contributor. Land-based sources include litter, trash, and debris from construction, ports, marinas, commercial and industrial facilities, and trash blown out of garbage containers, trucks, and landfills. Ocean-based sources include overboard discharges from ships and discarded fishing gear.
The presence of plastic in the ocean has detrimental effects on marine life. Marine animals, such as fish, seabirds, and mammals, can become entangled in plastic debris, leading to injuries, starvation, suffocation, and even death. Additionally, they may mistake plastic for food and ingest it, causing obstruction in their respiratory and digestive tracts. The ingestion of plastic has been observed in various species, including turtles, seabirds, and whales.
The impact of plastic pollution extends beyond the immediate harm to marine life. Floating plastics in the oceans can accumulate pollutants and transport them through ocean currents. These pollutants can be absorbed by marine life that ingests plastics, leading to the transfer of toxic chemicals up the food chain, eventually reaching humans who consume seafood.
Addressing plastic pollution requires a combination of prevention and cleanup efforts. Prevention involves reducing the use of disposable and single-use plastic products and improving waste management practices. Cleanup methods include trapping plastic particles at river mouths before they enter the ocean and targeting ocean gyres, where floating plastics tend to collect.
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Ocean acidification
Marine pollution is a combination of chemicals and trash, most of which comes from land sources. It includes plastic pollution, nutrient pollution, toxins, and underwater noise. Ocean acidification is a type of marine pollution that is affecting the entire world's oceans, including coastal estuaries and waterways.
When CO2 is absorbed by seawater, a series of chemical reactions occur, resulting in an increased concentration of hydrogen ions. This increase causes the seawater to become more acidic and leads to a decrease in the availability of carbonate ions. Carbonate ions are important building blocks for structures such as sea shells and coral skeletons. As ocean acidification increases, the availability of carbonate ions decreases, making it more difficult for calcifying organisms such as oysters, clams, sea urchins, corals, and mollusks to build and maintain their shells and other calcium carbonate structures.
A lower ocean pH has potentially harmful effects on marine organisms. Scientists have observed reduced calcification, lowered immune responses, and reduced energy for basic functions such as reproduction. Ocean acidification can also impact marine food chains and ecosystems that many people rely on for food and livelihoods, such as fishing and tourism.
One of the solutions to address the root cause of ocean acidification is to reduce carbon dioxide emissions, which is a primary objective of climate change mitigation measures.
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Nutrient pollution
In agriculture, the use of chemical fertilisers and animal manure contributes to nutrient pollution. When excess nutrients from these sources enter waterways, they stimulate the growth of phytoplankton and algae, leading to algal blooms. These blooms can be toxic to marine life and humans, causing oxygen depletion in the water and resulting in the death of marine organisms. Eutrophication, as this process is called, also leads to reduced water clarity and the loss of critical habitats such as coral reefs, seagrass meadows, and mangrove forests.
The consequences of nutrient pollution are severe and far-reaching. It disrupts delicate marine ecosystems, destroys habitats, and leads to oxygen depletion, creating "dead zones" where marine life struggles to survive. These issues are further exacerbated by climate change and other human activities. To address nutrient pollution, it is essential to reduce nutrient inputs into coastal marine ecosystems through better monitoring and management practices, including restoring habitats such as mangroves and marshes that can help remove nutrients from water before they reach the sea.
While challenging, it is crucial to address the multifaceted problem of nutrient pollution to protect marine life, maintain biodiversity, and safeguard human health. This requires a collaborative effort involving scientists, policymakers, and the public to implement effective solutions.
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Chemical contamination
Marine pollution is a pressing issue that poses a threat to marine life, ecosystems, and human health. Chemical contamination, also known as nutrient pollution, is a significant contributor to this crisis. This type of pollution arises from human activities, particularly the use of fertilisers and agricultural practices, which cause the runoff of chemicals into waterways that eventually reach the ocean.
The runoff of nutrients, specifically nitrogen and phosphorus, from intensive agriculture and fertiliser use, is a primary concern. This excess of nutrients promotes the growth of harmful algal blooms, which have detrimental effects on both wildlife and humans. When these dense algal blooms die off, their decomposition leads to severe oxygen depletion in the water, creating "dead zones" where marine life struggles to survive. This, in turn, impacts fisheries and tourism, affecting local economies.
Moreover, chemical contamination in marine environments includes a range of toxic substances. These toxins include crude oil and petroleum products, pesticides, pharmaceuticals, and personal care products. Even chemicals banned decades ago, like polychlorinated biphenyls (PCBs), still persist in high concentrations in deep-sea creatures. These chemicals accumulate in the food chain, resulting in contamination levels in larger animals that are significantly higher than in the surrounding water.
In addition to the direct impact on marine life, chemical contamination also poses risks to human health. Small organisms ingest toxins, which are then passed on to larger predators, including seafood consumed by humans. This transfer of toxins can lead to long-term health issues, cancer, and birth defects. For instance, mercury, carried down to the ocean's surface, is absorbed by phytoplankton and transferred up the food chain, resulting in high mercury levels in larger fish like swordfish.
Furthermore, chemical pollution extends beyond the contamination of water. Atmospheric pollution, where objects are carried by wind into the ocean, contributes to chemical contamination. This includes single-use plastics, which take hundreds of years to biodegrade, and styrofoam containers. Additionally, mining activities can release minerals and pollutants into nearby waterways, with copper being a common industrial pollutant that interferes with the development of coral polyps.
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Frequently asked questions
Marine pollution is the introduction of harmful substances or energy by humans into the marine environment, which results in harmful effects on marine life and ecosystems.
Marine pollution can be categorised into three main types: direct discharge of waste into the oceans, runoff into the waters due to rain, and pollutants released from the atmosphere. Common types of marine debris include plastic items, such as shopping bags, bottles, and fishing gear, as well as chemicals like nitrogen and phosphorus, which can cause harmful algal blooms.
Marine pollution comes primarily from land-based sources, with 80% of the pollution originating on land due to human activities. This includes littering, poor waste management, storm winds, and runoff from agricultural and industrial activities. Oil spills from ships and mining activities can also contribute to marine pollution.
Marine pollution has far-reaching consequences, damaging the environment, the health of organisms, and economic structures worldwide. It can harm or kill marine animals through ingestion or entanglement, and it can also interfere with navigation safety. Pollutants can accumulate in the food chain, impacting the health of marine species and humans who consume seafood.
