Ocean Pollution: Which Ocean Suffers More?

The ocean comprises about three-quarters of the Earth's surface, and it is classified into five distinct areas: the Pacific, Atlantic, Indian, Southern (Antarctic), and Arctic Oceans. Every area of the ocean is polluted, and the type of pollution varies. For instance, some water pollution starts as air pollution, which settles into waterways and oceans. Rainwater and agricultural runoff carry pollutants such as fertilisers, pesticides, and herbicides into the water. Oil spills and freight tanker accidents are also significant sources of ocean pollution. However, the Pacific Ocean is the most polluted ocean, with 2 trillion plastic pieces, and one-third of the plastic found in this ocean circulates in the North Pacific Gyre, also known as the Great Pacific Garbage Patch.

Plastic pollution

The majority of the garbage entering the ocean each year is plastic. Single-use plastic bags, water bottles, straws, and containers do not biodegrade but persist in the environment for extended periods, polluting beaches, entangling marine life, and being ingested by various species. Plastic debris has even been discovered at the bottom of the deepest ocean trenches, highlighting the extent of the issue.

The sources of plastic pollution are diverse, with 80% of marine litter originating from land-based sources, including those far inland, and making its way to the ocean via storm drains, sewers, and other pathways. A 2021 study revealed that 44% of plastic debris in rivers, oceans, and shorelines consisted of items related to takeout meals, such as bags, bottles, and containers. The production and disposal of plastic materials have turned our planet into a dumping ground for an alarming array of plastic debris, with an estimated 19-23 million tonnes of plastic waste leaking into aquatic ecosystems annually.

The impact of plastic pollution on marine life is severe. Marine mammals, such as whales and turtles, can become entangled in plastic debris, leading to injury or death. Additionally, they may mistake plastic for food, ingesting items like plastic bags and bottle caps. This ingestion of plastic introduces harmful substances into their bodies, as plastics can concentrate pollutants up to a million times their level in seawater. Microplastics, in particular, pose a significant threat as they can be consumed by small marine organisms, leading to the proliferation of plastics through the food chain.

Addressing plastic pollution is crucial for safeguarding ecosystems, preserving biodiversity, and promoting a sustainable future. While individual actions, such as reducing plastic consumption and participating in local clean-up efforts, are important, large-scale systemic change led by governments and industries is necessary to tackle this global issue effectively.

Chemical contamination

Marine pollution is a pressing issue, with the ocean absorbing approximately a quarter of all anthropogenic carbon emissions, leading to acidification and a rise in pH levels. Chemical contamination, a significant aspect of marine pollution, occurs when human activities introduce harmful substances into the ocean. This contamination can have detrimental effects on marine ecosystems, wildlife, and even human health.

Agricultural activities, such as the use of fertilizers and pesticides, result in chemical runoff that flows into waterways and ultimately reaches the ocean. This nutrient pollution increases the concentration of chemicals like nitrogen and phosphorus, promoting the growth of toxic algal blooms that harm wildlife and disrupt local industries. Additionally, pesticides like DDT, which have been banned or restricted in developed nations, continue to be used in underdeveloped countries, posing a significant threat to both environmental and human health.

Another source of chemical contamination is the release of industrial chemicals, such as those found in manufacturing, pharmaceuticals, and personal care products. These chemicals can enter the ocean through runoff, sewage, and ineffective water treatment systems. For example, perfluoroalkyl substances (PFAS) are used in the manufacture of non-stick cookware, stain-repellent fabrics, water-repellent clothing, and firefighting foam. PFAS chemicals are highly persistent and have contaminated surface waters and groundwater, eventually making their way into the ocean and incorporating themselves into the marine food chain.

The impact of chemical contamination extends beyond the immediate ecological consequences. Pollutants like methylmercury and PCBs have known adverse effects on human health, especially for vulnerable populations in low-income countries, small island nations, and indigenous communities. Exposure to these contaminants, through the consumption of contaminated seafood, can lead to brain damage, reduced IQ, and increased risks for developmental disorders in infants.

Addressing chemical contamination in the oceans requires a multifaceted approach. It involves implementing stricter regulations on the use and disposal of chemicals, improving waste management practices, and advocating for climate policies that prioritize the health of marine ecosystems. Additionally, public education and individual actions, such as reducing plastic consumption and participating in local waterway cleanups, can collectively contribute to mitigating chemical contamination in our oceans.

Noise pollution

Marine animals, such as whales, dolphins, and porpoises, are highly dependent on underwater sound for their survival. They use sound to navigate, communicate, find food, locate mates, and avoid predators. The loud noises generated by human activities interfere with these essential activities, resulting in serious, and sometimes fatal, consequences. For example, noise pollution can cause hearing loss in marine mammals, impacting their ability to survive in the ocean.

One of the primary sources of ocean noise pollution is shipping. The propellers, hull vibrations, and diesel engines of ships produce low-frequency sounds that overlap with the frequency range used by whales and other marine mammals. As a result, the sound levels in the ocean significantly increase when a vessel passes by, particularly in well-travelled routes, coastal areas, and near ports and harbors. This increase in noise pollution can disrupt the social networks of whales and impede their reproductive success.

Underwater blasts, sonar, and seismic surveys are also significant contributors to ocean noise pollution. Sonar, for example, has been found to alter the feeding behavior of endangered blue whales. Even at lower sound levels, the presence of sonar caused the whales to stop feeding, increase their swimming speed, and move away from the sound source. This can have far-reaching impacts on the health and population of these whale species.

Additionally, marine dredging, used to deepen or widen channels for ships, can also increase sound levels in the ocean. The intense noise generated by this activity can reach up to 180 dB re 1µPa @ 1 m and an intensity of 500 Hz. Oil and gas activities, such as drilling and the placement of offshore structures, contribute to underwater noise pollution as well, with their machinery and propellers generating sounds of up to 135 dB re 1µPa @ 1 m and intensities up to 100 Hz.

To address the issue of ocean noise pollution, international institutions and organizations like the International Ocean Noise Coalition (IONC) are advocating for regulations and precautions in the creation of anthropogenic ocean noise. There is a growing recognition of the threat that noise pollution poses to marine wildlife, and researchers are working to understand the full extent of the damage caused by humanity's growing acoustic footprint in the oceans.

Fossil fuel emissions

Oceans absorb a significant portion of the world's carbon emissions from the burning of fossil fuels, currently estimated at 25%. This figure has been increasing, with a fourfold increase in ocean carbon uptake from 1994 to 2007 compared to the period from the start of the Industrial Revolution in 1800 to 1994. As a result, the pH of the ocean's surface waters has increased by an estimated 30% since the Industrial Revolution, leading to ocean acidification. If greenhouse gas emissions continue to rise, ocean surface waters are projected to become nearly 150% more acidic by the end of the century. This will have significant impacts on marine ecosystems and the economies that depend on them.

The burning of fossil fuels releases hazardous air pollutants such as sulfur dioxide, nitrogen oxides, particulate matter, carbon monoxide, and mercury. These pollutants contribute to air pollution, which can then lead to acid rain, eutrophication, crop and forest damage, and adverse effects on wildlife and human health. Additionally, the extraction, transportation, and refining of fossil fuels carry the risk of oil spills, which can have devastating consequences for marine environments, wildlife, and coastal communities.

Oil spills can result in the contamination of water bodies, destroying habitats, eroding shorelines, and impacting beaches and parks. One example of the harmful effects of oil spills is the Deepwater Horizon oil spill in the Gulf of Mexico in 2010, which resulted in the death of marine life and had long-lasting ecological and economic consequences for the region.

Furthermore, the fracking process used in fossil fuel extraction can lead to water pollution. Fracking requires a substantial amount of water, and the resulting wastewater can be toxic, containing substances like arsenic, lead, chlorine, and mercury. These contaminants can pollute groundwater and drinking water sources, posing risks to both environmental and human health.

In addition to the direct impacts on water quality, fossil fuels are also a major contributor to plastic pollution in oceans. Over 99% of plastics are derived from fossil fuels, and a significant portion of the 300 million tons of plastic waste generated globally each year ends up in the oceans. Plastic pollution in oceans has severe consequences for marine life, as it can be ingested or lead to entanglement, disrupting the natural habitats and food chains of various species.

To address the issue of fossil fuel emissions and their impact on ocean water pollution, there have been efforts to transition towards more sustainable practices. For instance, the NRDC (Natural Resources Defense Council) has played a crucial role in halting offshore drilling and seismic blasting in the Arctic and Atlantic Oceans, advocating for the protection of marine ecosystems and fisheries that support billions of people worldwide.

Land-based sources

Marine pollution is one of the greatest threats to the health of the world's oceans, and about 80% of it comes from land-based sources. These sources include plastic pollution, agricultural runoff, industrial and municipal waste, marine litter, and oil spills.

Plastic pollution is a significant contributor to land-based marine pollution. Single-use plastic items such as bags, water bottles, straws, and containers do not biodegrade and can persist in the environment for hundreds of years. These plastics end up in the ocean, polluting beaches, entangling marine life, and being ingested by marine animals, causing harm or even death. Plastic debris has been found in all oceans, from the surface to the deepest trenches.

Agricultural runoff is another major land-based source of marine pollution. Fertilizers, pesticides, and other chemicals used in agriculture can wash into nearby water bodies and eventually make their way into the ocean. These chemicals can cause algae blooms, create dead zones, and harm marine life. Additionally, nutrients from aquaculture and tourism sources also contribute to nutrient waste in coastal waters.

Industrial and municipal waste also play a role in land-based marine pollution. Industrial discharges can release a range of pollutants, including heavy metals, chemicals, and untreated wastewater into water bodies, which eventually flow into the ocean. Municipal waste, such as litter and sewage, can also find its way into the ocean through storm drains, sewers, and rivers, contributing to the formation of garbage patches.

Oil spills are another significant form of land-based marine pollution. While they may occur at sea, they often originate from onshore or land-based sources, such as oil drilling, transportation, or storage facilities. These spills can have devastating and long-lasting effects on marine ecosystems, wildlife, and coastal communities.

Addressing land-based marine pollution is complex due to the variety of substances and activities involved, as well as the potential impact on a state's economic and industrial development. However, efforts are being made to combat this issue. The Regional Seas Programme, for example, works with member states to implement region-specific strategies to tackle both land- and sea-based sources of pollution. Additionally, the United Nations Environment Programme (UNEP) has established guidelines, such as the Montreal Guidelines, to provide a framework for protecting the marine environment from land-based pollution.

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