Ocean Pollutants: Earth's Structure Under Threat

Marine pollution is a combination of chemicals and trash, most of which comes from land sources. It results in damage to the environment, the health of all organisms, and economic structures worldwide.

The two main types of marine pollution are chemical contamination and trash. Chemical contamination, or nutrient pollution, occurs when human activities, such as the use of fertilizer on farms, lead to the runoff of chemicals into waterways that ultimately flow into the ocean. The increased concentration of chemicals in the coastal ocean promotes the growth of algal blooms, which can be toxic to wildlife and harmful to humans.

Marine trash includes all manufactured products, most of which are plastic, that end up in the ocean. These products are often single-use plastics, such as shopping bags and beverage bottles. Marine trash poses dangers to both humans and animals. Fish become tangled and injured in the debris, and some animals mistake items like plastic bags for food and eat them. Small organisms feed on tiny bits of broken-down plastic, called microplastics, and absorb the chemicals from the plastic into their tissues.

Marine pollution has multiple negative impacts on marine ecosystems, and these impacts are exacerbated by global climate change. Petroleum-based pollutants reduce photosynthesis in marine microorganisms that generate oxygen. Increasing absorption of carbon dioxide into the seas causes ocean acidification, which destroys coral reefs, impairs shellfish development, and increases the toxicity of some pollutants.

Nonpoint source pollution: Runoff from farms, septic tanks, vehicles, boats, and other sources can carry agricultural fertilisers and pesticides into the ocean

Nonpoint source pollution is a major contributor to the contamination of the ocean. Nonpoint source pollution refers to the contamination of water bodies from diffuse sources, such as runoff from farms, septic tanks, vehicles, and boats. These sources can carry agricultural fertilisers and pesticides into the ocean, affecting both the structure and health of marine ecosystems.

Fertilisers and pesticides from farms can be carried into the ocean through runoff. This can lead to an increase in harmful algal blooms, which can have toxic effects on marine life and disrupt the marine food chain. For example, increased levels of nitrogen and phosphorus from fertilisers can stimulate algal blooms, leading to hypoxic (low oxygen) conditions that are harmful to aquatic life.

Septic tanks can also contribute to nonpoint source pollution. Failing septic systems can release bacteria, viruses, and nutrients into the environment, which can contaminate nearby water bodies and pose risks to human health.

Additionally, vehicles and boats can release oil, grease, and toxic chemicals into the ocean. These pollutants can have detrimental effects on marine life and disrupt the natural balance of marine ecosystems.

The impact of nonpoint source pollution on the ocean is far-reaching and can have long-lasting effects on both the structure and health of marine ecosystems. It is important to address these sources of pollution to mitigate their effects on the ocean and protect the planet's delicate marine ecosystems.

Point source pollution: Discharge from faulty or damaged factories or water treatment systems

Point source pollution is defined by the U.S. Environmental Protection Agency (EPA) as "any single identifiable source of pollution from which pollutants are discharged, such as a pipe". Factories and sewage treatment plants are two common types of point sources. Factories, including oil refineries, pulp and paper mills, and chemical, electronics and automobile manufacturers, typically discharge one or more pollutants in their discharged waters (called effluents). Some factories discharge their effluents directly into a waterbody. Others treat it themselves before it is released, and still, others send their wastes to sewage treatment plants for treatment. Sewage treatment plants treat human wastes and send the treated effluent to a stream or river.

Another way that some factories and sewage treatment plants handle waste material is by mixing it with urban runoff in a combined sewer system. Runoff refers to stormwater that flows over surfaces like driveways and lawns. As the water crosses these surfaces, it picks up chemicals and pollutants. This untreated, polluted water then runs directly into a sewer system.

When it rains excessively, a combined sewer system may not be able to handle the volume of water, and some of the combined runoff and raw sewage will overflow from the system, discharging directly into the nearest waterbody without being treated. This combined sewer overflow (CSO) is considered point source pollution, and can cause severe damage to human health and the environment.

Large farms that raise livestock, such as cows, pigs and chickens, are other sources of point source pollution. These types of farms are known as concentrated animal feeding operations (CAFOs). If they do not treat their animals' waste materials, these substances can then enter nearby waterbodies as raw sewage, radically adding to the level and rate of pollution.

To control point source discharges, the Clean Water Act established the National Pollutant Discharge Elimination System (NPDES). Under the NPDES program, factories, sewage treatment plants, and other point sources must obtain a permit from the state and EPA before they can discharge their waste or effluents into any body of water. Prior to discharge, the point source must use the latest technologies available to treat its effluents and reduce the level of pollutants.

Air pollution: Dirt, top soil, and silt from fields or construction sites can run off into waterways, harming fish and wildlife habitats

Air pollution is a complex mixture of toxic metals, plastics, manufactured chemicals, petroleum, urban and industrial wastes, pesticides, fertilizers, pharmaceutical chemicals, agricultural runoff, and sewage.

Dirt, topsoil, and silt from fields or construction sites can run off into waterways, harming fish and wildlife habitats. This is due to the fact that silt is a fine-grained soil that can be washed into streams after heavy rainstorms. This can clog the gills of fish and other macro-invertebrates, causing them to suffocate and die. It also impacts the amount of sunlight that can penetrate the water, which is necessary for aquatic plants to photosynthesize.

Additionally, dirt can be coated with harmful pollutants like herbicides, pesticides, fertilizers, and oil. These pollutants can kill plants and insects in the stream. Fertilizers can also cause algal blooms, which disrupt the natural balance in the stream and deplete the oxygen supply.

Noise pollution: Human-generated noise can alter the underwater acoustic landscape, harming marine species

Noise pollution in the ocean is a growing issue, with human activities such as shipping, boating, and energy exploration increasing noise levels in coastal and offshore habitats. These rising noise levels can have detrimental effects on marine life, impacting their ability to communicate, find prey, and navigate their surroundings.

• Interference with communication and vital cues: Marine species rely on sound for vital functions such as finding prey, locating mates, and avoiding predators. Noise pollution can interfere with these acoustic signals, hindering their ability to communicate and receive important environmental cues.
• Hearing loss and behavioural changes: Very loud noises can cause hearing loss in marine mammals and even lead to death. Additionally, foreign sounds can disrupt their natural behaviour, causing them to move away from their usual habitats or alter their feeding and anti-predatory behaviours.
• Physiological changes and increased stress: Noise pollution can induce physiological changes in marine mammals, such as increased stress levels and changes in metabolism.

Noise pollution can have far-reaching impacts on the ocean's ecosystem. By disrupting the natural acoustic landscape, it can alter the behaviour and distribution of marine species, leading to changes in population dynamics and food webs. This, in turn, can affect the ocean's biodiversity and the overall health of marine ecosystems.

Mitigating noise pollution

To reduce the impact of noise pollution on marine life and the ocean's structure, it is essential to implement measures such as:

• Reducing propeller noise from ships
• Mitigating the sounds of sonar equipment, seismic air guns, and construction activities
• Developing quieter technologies

Oil spills: Oil spills from boats, airplanes, cars, trucks, and lawn mowers can linger in the ocean for decades, causing irreversible damage to marine ecosystems

Oil spills from boats, airplanes, cars, trucks, and lawn mowers can have a devastating impact on marine life and ecosystems, causing irreversible damage that can last for decades. Oil spills occur when crude oil is released into the environment due to human activity, often during the transportation, use, or acquisition of oil. While some spills are small, others are major, such as the Deepwater Horizon spill in the Gulf of Mexico in 2010, which released over 134 million gallons of oil into the ocean.

Oil spills can affect marine life in a variety of ways. Oil can coat the feathers and fur of animals, reducing their ability to maintain body temperature and affecting their natural buoyancy, causing them to drown. It can also smother smaller species of fish and invertebrates, and impact their ability to breathe or see. Oil spills can disrupt the breeding and reproduction of marine animals, contaminating nests on shore and affecting the viability of eggs. Additionally, the toxic chemicals in oil can cause internal damage to animals through ingestion or inhalation, leading to organ damage and gastrointestinal issues.

The impact of oil spills on marine birds is particularly severe. Birds are highly likely to ingest oil as they preen themselves, and oil-coated birds often lose their ability to fly and escape danger. It is estimated that less than 1% of oil-covered birds survive, even with medical attention. Seabirds are also among the most affected by oil spills, as they are found on the sea surface or shorelines, where oil accumulates.

The effects of oil spills can be long-lasting, with toxic chemicals remaining in the ocean for years and sinking to the seafloor, poisoning the sediment. This can impact the food sources for marine life, making them less available or of poorer quality. Restoration efforts after oil spills can be time-consuming and costly, and even the most advanced cleanup methods only remove a fraction of the oil.

Oil spills have far-reaching consequences, not only for marine life but also for the environment, society, and the economy. They can lead to social unrest, as people are upset by the harm caused to marine life and call on governments to take action. Oil spills can also result in a decrease in tourism and negatively impact industries such as fishing and shrimping, which rely on thriving populations of marine life.

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