Human Pollution's Impact On Our Ocean Ecosystems

Human pollution of the ocean is a pressing issue that poses a clear and present danger to human health and well-being. It is estimated that over 3 billion people are at risk of the harmful effects of ocean pollution, which include hormonal issues, reproductive issues, and damage to the nervous system and kidneys.

Ocean pollution is caused primarily by human activities, with over 80% of ocean pollution coming from land-based sources, such as runoff, rivers, atmospheric deposition, and direct discharges. The most visible component of ocean pollution is plastic debris, which is rapidly accumulating and killing marine life. However, it is the invisible chemicals, particles, metals, and biological toxins that have been shown to have the most significant impact on human health.

Coal combustion is the major source of mercury pollution in the oceans, which can cause developmental issues and increase the risk of heart disease and dementia in adults. In addition, the textile industry is a key player in ocean pollution, with toxic wastewater discharge and microplastic pollution.

To address ocean pollution, it is recommended to ban coal combustion and single-use plastics, improve waste management, reduce agricultural runoff, and expand marine protected areas.

Mercury pollution

Mercury is a heavy metal that cycles through the atmosphere, water, and soil in various forms to different parts of the world. Mercury pollution is a global problem, and awareness has been raised on an international action plan to minimize anthropogenic mercury emissions and clean up mercury pollution. Mercury is released through both natural and anthropogenic processes. Natural processes are mainly geogenic, such as volcanic activities and land emissions through the soil. Volcanoes release mercury from underground reservoirs upon eruption.

Anthropogenic emissions alone have increased mercury concentration in the environment by threefold. The main anthropogenic sources of mercury emission are artisanal and small-scale gold mining, fossil fuel burning, and primary production of non-ferrous metals. Mercury can enter the ocean in different ways, such as atmospheric deposition, rivers, estuaries, sediments, and hydrothermal vents. Once in the ocean, mercury can undergo many reactions, including redox reactions, adsorption processes, methylation, and demethylation.

Mercury can bioaccumulate in marine food chains in the form of highly toxic methylmercury, which can cause health risks to human seafood consumers. Most human exposure to mercury is from eating contaminated fish and shellfish. Mercury consumption can result in loss of peripheral vision, weakened muscles, impairment of hearing and speech, and deteriorated movement coordination. Infants and developing children are at an even higher risk, as mercury exposure inhibits proper brain and nervous system development, damaging memory, cognitive thinking, language abilities, attention, and fine motor skills.

Plastic waste

The dangers of microplastics to human health are still largely unknown. However, studies have found that toxins in plastics cause several health issues, including cancers, immune system problems, and congenital disabilities.

Microplastics also threaten the lives of birds and other beings that depend on oceanic life forms for their food. Most of the time, these beings suffer from ingesting plastic or suffocation.

Additionally, plastic waste in the ocean can smother coral colonies, preventing light from reaching the phototrophic organisms that build reefs. It can also cause physical damage to reefs.

Harmful algal blooms

The most common type of HABs in the United States are produced by cyanobacteria, which are bacteria that perform photosynthesis. Some, though not all, types of cyanobacteria can produce dangerous cyanotoxins. The most frequently reported type of bloom-forming cyanobacteria is Microcystis.

HABs occur both naturally in the environment and as a result of human activities, but the latter are vastly increasing the frequency, prevalence, and toxicity of HABs. The following are some of the main freshwater algal bloom causes:

• Nutrient pollution, such as nitrogen and phosphorus, which are found in agricultural fertilizers and lawn care products, which wash out into our waterways.
• Warm water gives cyanobacteria a competitive advantage. These bacteria grow faster than more benign algae in higher temperatures, and once a bloom forms, a feedback loop can be triggered.
• Slow-moving or stagnant water can also become thermally stratified, meaning that a layer of warm water, which favors algal blooms, floats on top of cooler water.
• Climate change is both increasing the frequency and duration of droughts in many parts of the country and intensifying extreme storms. Periods of drought interspersed with strong precipitation increase runoff from agricultural lands, lawns, and other sources, leading to higher nitrogen levels in rivers—and therefore harmful algal blooms.
• Burning fossil fuels, deforestation, and land development are increasing the amount of carbon dioxide in the atmosphere. This fuels harmful algal blooms because cyanobacteria can feed on the carbon dioxide not only present at the surface of a water body but also dissolved in the water.
• Climate change and more severe droughts also modify the flow regime in freshwater bodies and can increase competition for ever-scarcer freshwater supplies.
• Inadequate water treatment facilities can compromise water quality and threaten public health, and disrupt or even shut down treatment plants.
• HABs can also be costly in economic terms. HABs can result in reduced tourism, closed beaches and shellfish beds, and decreased catch from recreational and commercial fisheries. Experts estimate that HABs cost the U.S. economy at least $82 million a year.

Oil spills and chemical wastes

When oil is released into the ocean, it forms a thin oil slick that spreads rapidly across the water's surface. This oil slick can kill wildlife, destroy habitats, and contaminate critical resources in the food chain. Oil spills can also have severe economic impacts, forcing the closure of fisheries, reducing tourism, and disrupting navigation routes.

One of the most well-known oil spills in recent history was the Deepwater Horizon oil spill in the Gulf of Mexico in 2010, which resulted in the release of more than 134,000 barrels of oil. This spill had devastating consequences for marine life and the local economy.

In addition to oil spills, chemical wastes are also a significant source of ocean pollution. These wastes include mercury, plastic waste, manufactured chemicals, agricultural runoff, and biological threats like harmful algal blooms. Mercury, a toxic metal, is released into the ocean primarily through coal combustion and small-scale gold mining. Plastic waste, which makes up about 80% of marine pollution, breaks down into microplastics that are ingested by marine life and can enter the human food chain.

Chemical wastes from industrial sources and runoff from land can also contaminate water supplies and the food chain. These toxic chemicals, such as oil, mercury, lead, pesticides, and other heavy metals, can have harmful effects on human health, including hormonal issues, reproductive problems, and damage to the nervous system and kidneys.

To address the issue of oil spills and chemical wastes, organizations like the National Oceanic and Atmospheric Administration (NOAA) provide scientific expertise, data, and assistance to help respond to and mitigate the impacts of these incidents.

Microplastics

The effects of microplastics on human health are not yet well understood, but there is a high level of uncertainty about their potential hazard. Studies have shown that microplastics can cause biochemical and structural damage, with noticeable dysfunctions of the intestine, liver, and excretory and reproductive systems. They can also enhance the toxic effects of other pollutants, such as organophosphates, phthalates, and sodium dextran sulfate.

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