Bronte Wells
Marine pollution is a pressing issue that poses a threat to the health of our planet, with billions of pounds of trash and debris entering the ocean each year. Eighty percent of this pollution comes from land-based sources, such as runoff pollution from farms, sewage systems, and industrial waste. Single-use plastics are a significant contributor, with plastic debris transforming marine areas into a plastic soup, leading to the choking and poisoning of marine life. Other sources include ship pollution, deep-sea mining, and atmospheric pollution from wind-blown debris. These pollutants have severe consequences for marine ecosystems, human health, and the environment, with long-term impacts on marine life, water quality, and climate regulation.
| Characteristics | Values |
|---|---|
| Plastic waste | Single-use plastic items, such as bags, bottles, and packaging, are abundantly used and dumped into the marine environment. Plastic debris can take hundreds of years to decompose and is often ingested by marine life, causing choking and potential large-scale impact on the ecosystem. |
| Chemical contamination | Human activities, such as the use of fertilizers and pesticides on farms, lead to the runoff of chemicals into waterways that eventually flow into the ocean. Increased concentrations of chemicals, including nitrogen and phosphorus, promote the growth of toxic algal blooms, which can harm both marine life and humans. |
| Industrial waste | Dangerous toxins and industrial chemicals are often dumped into water bodies due to their ease of disposal. These toxins accumulate in the fatty tissues of aquatic fauna, leading to reproductive issues and biomagnification up the food chain, ultimately reaching humans through seafood consumption. |
| Agricultural waste | Agricultural activities, including the use of fertilizers and animal waste, contribute to ocean pollution. Excess nutrients, such as nitrogen-rich compounds, can lead to eutrophication, causing explosive growth of algae and other microorganisms that deplete oxygen levels and disrupt the ocean ecosystem. |
| Oil spills | Ship pollution, including oil spills, is a significant source of ocean pollution. Crude oil is highly toxic to marine life and challenging to clean up. Oil spills also block sunlight from reaching aquatic flora and contribute to coral reef bleaching and habitat destruction. |
| Mining | Deep-sea mining and inland mining activities release pollutants into the ocean. Mining for materials such as copper and gold can interfere with the life cycles of marine organisms. Additionally, mining can cause physical damage to the ocean floor, increasing the region's toxicity and leading to leaks and corrosion. |
| Sewage | Septic system failures and poorly managed sewage infrastructure can result in the release of polluting substances and toxins directly into the ocean through rivers and drainages. |
| Atmospheric pollution | Objects from inland areas, including natural debris (dust, sand) and human-made debris (trash, plastic), can be blown by the wind over long distances and end up in the ocean. These items can remain suspended in ocean currents for years, entangling or being ingested by marine life. |
| Noise pollution | Noise from transportation and other human activities can interrupt the balance of marine life, causing clashes in ecosystems that have already been damaged by pollution. |
What You'll Learn
Plastic pollution
Plastics do not fully biodegrade but can persist for hundreds of years, exacerbating the long-term environmental impact. They undergo photodegradation when exposed to the sun, but this process is inhibited by water. As a result, plastic debris in the ocean disintegrates into smaller and smaller pieces, even down to the molecular level, making it challenging to remove. These microplastics are then ingested by marine organisms, from zooplankton to larger fish, leading to toxic substances entering the food chain and potentially impacting human health.
The sources of plastic pollution in the ocean are predominantly land-based, accounting for up to 80% of marine pollution. Land-based sources include runoff pollution, atmospheric pollution, and industrial and agricultural waste. Rivers and drainages carry sewage, polluting substances, and industrial and agricultural waste directly into the ocean. Atmospheric pollution occurs when objects, including plastic debris, are blown by the wind over long distances and end up in the ocean.
Additionally, ocean-based sources contribute to plastic pollution. Ship pollution, including lost cargo and oil spills, is a significant factor. Ghost nets, or abandoned fishing nets, entangle marine animals and continuously trap and kill them through a process called ghost fishing. Plastic waste from countries with inadequate waste management, such as China, Indonesia, and the Philippines, also contributes significantly to ocean plastic pollution.
To address plastic pollution, urgent global action is required. This includes improved waste management, plastic reduction strategies, and enhanced international cooperation. Individuals can contribute by reducing their use of single-use plastics, opting for reusable alternatives, and supporting environmental organizations working to combat plastic pollution.
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Industrial and agricultural waste
Agricultural Waste
Agriculture accounts for 70% of water withdrawals worldwide and plays a major role in water pollution. Farms discharge large quantities of agrochemicals, organic matter, drug residues, sediments, and saline drainage into water bodies. Soil erosion, nutrient loss, bacteria from livestock manure, and pesticides are the primary stressors on water quality. Increased levels of nitrogen and phosphorus from fertiliser and manure can stimulate algal blooms, leading to hypoxic conditions that are harmful to aquatic life. Algae blooms also affect the recreational use of local streams, downstream reservoirs, and estuaries.
Excessive sedimentation from erosion can overwhelm aquatic ecosystems, smother breeding areas, and degrade coastal and marine ecosystems, including coral reefs. Bacteria and nutrients from livestock and poultry manure can cause shellfish bed closures and affect drinking water supplies. Pesticide runoff poses risks to aquatic life, fish-eating wildlife, and drinking water sources.
A new class of agricultural pollutants, including veterinary medicines (antibiotics, vaccines, and growth promoters), has emerged in the last two decades. These pollutants move from farms through water to ecosystems and drinking water sources. Fish excreta and uneaten feeds from fed aquaculture also diminish water quality.
Industrial Waste
The ocean is threatened by a variety of polluting industries, including deep-sea mining, desalination, marine renewables, sand mining, submarine cables, and dredging and dumping. Offshore oil and gas production, which represents roughly 30% of global production, has a wide-ranging impact on marine habitats and wildlife. Noise pollution, spills, and habitat damage are some of the consequences of this industry.
Shipping is responsible for approximately 3.1% of global greenhouse emissions and contributes to pollution through dumped and spilled oil and waste, ballast water discharges, ship strikes, noise pollution, and dredging for shipping channels.
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Oil spills
Crude oil is extremely toxic to marine life and often proves fatal. It can directly suffocate sea creatures, including birds, sea mammals, fish, algae, and coral. Ingesting oil can also be harmful to animals, and it can damage their habitats and reproductive rates, hindering the long-term recovery of animal populations. Oil spills can also cause power plants and other utilities that draw on or discharge into seawater to shut down.
Cleanup operations for oil spills are challenging, and no entirely satisfactory method has been developed. Responses typically aim to contain the oil and remove enough of it to allow economic activity to resume and the natural recovery of the marine environment to take over. Floating booms can be used to contain the oil and prevent it from spreading, while skimming involves using various mechanisms to physically separate the oil from the water and place it into collection tanks. Sorbents such as straw, volcanic ash, and polyester-derived plastic shavings can also absorb oil from the water. In situ burning, or setting fire to an oil slick, can burn the oil away at sea, but this can cause air pollution and is only suitable in low wind conditions. Chemical dispersants can be used to dissipate oil slicks, but these have been shown to increase toxic hydrocarbon levels in fish.
While cleanup technologies have improved, preventing oil spills and reducing their impact on the marine environment remains a critical challenge.
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Land-based pollution
Industrial and agricultural waste is another major form of land-based pollution. The release of toxic chemicals and industrial waste into the ocean can have devastating effects on marine life and ecosystems. These toxins can accumulate in the tissues of aquatic organisms, leading to biomagnification as they move up the food chain, eventually reaching humans through seafood consumption. Additionally, the presence of nitrogen-rich fertilisers, animal wastes, and sewage can trigger explosive growths of algae and other microorganisms, further disrupting the ocean ecosystem and depleting oxygen levels in the water.
Plastic pollution is another significant form of land-based pollution. Single-use plastic items, such as shopping bags, bottles, and packaging, are commonly littered or improperly disposed of, making their way into oceans through rivers and storm drains. These plastics can take hundreds of years to decompose, breaking down into microplastics that are ingested by marine organisms, leading to choking and internal chemical contamination. Microplastics have been detected in various marine species, including plankton and whales, and can ultimately end up in the human food chain.
Another often overlooked source of land-based pollution is atmospheric pollution. Objects from inland areas, such as dust, sand, debris, and trash, can be carried over long distances by the wind and end up in the ocean. These items, particularly plastic debris, can remain suspended in ocean currents for years, entrapping or being ingested by marine animals.
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Mining
Secondly, mining produces large quantities of waste rock and tailings, which are often stored above ground. These waste materials contain harmful substances such as acid-generating sulphides, heavy metals, and other contaminants. Acid Mine Drainage (AMD) is a significant issue, as it occurs when sulphides in exposed rocks react with air and water, producing sulphuric acid. This acid can then be carried off the mine site by rainwater, ending up in nearby water sources, severely degrading water quality and killing aquatic life. Heavy metal contamination is another serious problem, with metals such as arsenic, cobalt, copper, and lead leaching into water sources and causing further pollution.
Additionally, the discharge of dredging spoils, marine litter, and cooling or ballast waters associated with mining activities can directly impact ocean ecosystems. The extraction process can increase seawater temperatures and reduce oxygen levels, affecting midwater ecosystems that connect deep-sea and shallow ecosystems and absorb carbon from the atmosphere.
Deep-sea mining, in particular, has emerged as a potential solution to meet the growing demand for critical minerals required for renewable energy technologies. However, it is not without its risks. The potential release of carbon dioxide trapped in the seabed, noise pollution, and light pollution from mining operations could all disrupt delicate marine ecosystems and lead to biodiversity loss. While regulations are being developed to govern deep-sea mining, there are still concerns about its environmental impacts, and some call for a moratorium until these are fully understood.
Overall, while mining is a significant contributor to sea pollution, there have been improvements in mining practices, and the development of clean mining technologies and strict environmental regulations provides hope for a more sustainable future.
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Frequently asked questions
Eighty percent of marine pollution comes from land-based sources, with single-use plastics being a major contributor.
Plastic waste is particularly harmful as it can take hundreds of years to decompose. Plastic debris can choke marine life, and when exposed to sunlight and ocean waves, it breaks down into microplastics, which are ingested by small organisms and make their way up the food chain.
Other significant sources of sea pollution include agricultural and industrial waste, oil spills, chemical contaminants, sewage, and ship pollution.
Sewage systems can fail, allowing waste to drain directly into the ocean. This introduces harmful toxins, chemicals, and nutrients that reduce oxygen levels and harm marine life and ecosystems.
Individuals can make small changes, such as reducing single-use plastic consumption, using organic fertilizers, and supporting initiatives that promote clean energy and proper waste management practices.
