Ocean Pollution: Coasts Suffer Most

Ocean water is most polluted near coasts due to human activities such as fossil fuel burning, offshore drilling, and plastic pollution. The majority of pollutants entering the ocean come from human activities along coastlines, with nonpoint source pollution from runoff being a significant contributor. This pollution includes plastic waste, sewage, oil, heavy metals, and chemical spills, which harm marine life and ecosystems. Additionally, noise pollution from human activities like naval sonar testing and offshore drilling can disrupt marine wildlife behaviour and drive species towards extinction. The impact of coastal pollution is widespread, affecting marine life, human health, and coastal economies dependent on marine resources.

Nonpoint source pollution from runoff, septic tanks, farms, etc

Nonpoint source (NPS) pollution is the leading cause of water quality issues, and it is a significant contributor to ocean water pollution near coasts. Unlike pollution from industrial or sewage treatment plants, NPS pollution comes from various diffuse sources, including runoff from land, precipitation, atmospheric deposition, drainage, seepage, or hydrologic modification. As rainfall or snowmelt moves over and through the ground, it picks up and carries natural and human-made pollutants, depositing them into coastal waters.

Runoff

Runoff is one of the biggest sources of NPS pollution. It includes stormwater runoff from residential, commercial, and agricultural areas, as well as construction sites, automotive facilities, and forestry operations. When rainwater or snowmelt flows over these surfaces, it can pick up pollutants such as oil, grease, chemicals, fertilisers, and sediment, carrying them into nearby water bodies.

Septic Tanks

Septic tanks can also contribute to NPS pollution. If a septic tank is not properly maintained or if it fails, sewage can leak into the surrounding soil and groundwater. From there, it can eventually make its way into coastal waters, contaminating them with harmful bacteria and nutrients.

Farms

Agricultural practices can have a significant impact on NPS pollution. Farmland can be a source of runoff, especially if it has been treated with pesticides, herbicides, or fertilisers. Animal waste from farms can also contaminate water sources, leading to high nutrient levels that can cause harmful algal blooms. Additionally, irrigation practices can impact water quality, as agricultural stormwater discharges and return flows from irrigated agriculture are not considered point sources and are often exempt from regulation.

To address NPS pollution from these sources, it is essential to implement best management practices and take positive steps to reduce their impact. This includes proper waste disposal, minimising the use of chemicals, and adopting sustainable farming practices. By working together with various agencies and programs, such as NOAA's Coastal Zone Management Program, we can develop effective plans to control and reduce NPS pollution near coastal areas.

Point source pollution from oil spills, chemical spills, etc

Ocean water is most polluted near coasts due to point-source pollution, which is contamination from a single source. This includes oil spills, chemical spills, wastewater discharge, and illegal dumping. Oil spills, in particular, have devastating effects on marine life and coastal economies. When oil is spilled into the ocean, it spreads quickly, coating animals and plants and leading to poisoning or suffocation. The toxic chemicals from oil spills can sink to the seafloor, poisoning the sediment and affecting sedimentation rates, which are crucial for the food sources and habitats of some animals.

Oil spills frequently occur where oil is drilled, transported, or used, including offshore drilling platforms and pipelines. For example, in 2015, a pipeline leak in California left crude oil along beaches and contaminated critical marsh and wetland habitats. Similarly, in 2010, the Deepwater Horizon oil spill in the Gulf of Mexico released over 134 million gallons of oil, impacting the coastline and marine life, including bottlenose dolphins, even years later.

In addition to oil spills, chemical spills and other point-source pollution contribute to the problem. Contaminants such as chemicals, nutrients, and heavy metals are carried from farms, factories, and cities into bays, estuaries, and eventually the sea. This type of pollution can have long-lasting effects on the environment and human health, with contaminated water causing approximately 1.8 million deaths in 2015, according to a study published in The Lancet.

To address point-source pollution, organizations like the National Oceanic and Atmospheric Administration (NOAA) in the United States play a crucial role. NOAA's experts evaluate the impact of spills, track contamination, and design restoration projects to help the ocean recover. They also work to recover funds from responsible parties and provide science-based expertise to support decision-making during emergency operations.

Plastic pollution from single-use plastic bags, bottles, etc

Plastic pollution is a pressing issue that requires global cooperation and concerted action. It is primarily caused by the improper disposal and mismanagement of single-use plastic items such as bags, bottles, and other disposable products. These items, designed for temporary convenience, have a lasting and detrimental impact on the environment, particularly coastal and marine ecosystems.

Single-use plastic bags, bottles, and other disposable items contribute significantly to plastic pollution in the ocean. The production and consumption of plastic have increased exponentially, with humans generating over 400 million metric tons of plastic annually. While less than 0.5% of this plastic ends up in the ocean, the amount that does is still substantial, with an estimated 1-2 million tons of plastic entering marine environments each year.

Rivers are the primary conduits for transporting plastic from land to sea. During storms and heavy rainfall events, the amount of plastic entering waterways can increase significantly. Coastal cities in middle-income countries are particularly vulnerable to becoming plastic emissions hotspots due to their proximity to rivers and coastlines, as well as inadequate waste management infrastructure.

Once in the ocean, plastic can remain in coastal waters for years before being carried out to the open sea by rotating ocean currents called gyres. These gyres create massive circular currents that trap floating plastic for decades or even centuries. The most well-known gyre is the Great Pacific Garbage Patch, located between Hawaii and California. It is estimated to be twice the size of Texas and is primarily composed of plastic from land-based sources and fishing activities.

The presence of plastic in the ocean has devastating consequences for marine life and ecosystems. Marine animals, such as seabirds, sea turtles, seals, and other mammals, ingest plastic or become entangled in it, leading to injuries and death. Additionally, floating plastic can transport invasive species, threatening marine biodiversity and the food web. Microplastics, which are tiny plastic particles, have also become ubiquitous in the marine environment, finding their way into the food chain and posing risks to human health.

To address plastic pollution from single-use plastic bags, bottles, and other disposable items, a multifaceted approach is necessary. It involves improving waste management practices, particularly in middle-income countries. This includes reducing plastic consumption, promoting recycling and proper disposal, and advocating for policy changes that regulate plastic as a hazardous pollutant. Individuals can make a difference by reducing their use of single-use plastics, reusing and recycling plastic items, and supporting initiatives that address plastic pollution.

Noise pollution from high-intensity sonar, seismic blasts, etc

Ocean water is most polluted near coasts due to human activities along coastlines. Noise pollution is one of the many types of pollution that affects the ocean, and it is primarily caused by human activities such as commercial shipping, oil exploration, seismic surveys, offshore wind turbine installation, and military sonar. These activities generate excessive and unnatural underwater sounds that can have detrimental effects on marine life.

High-intensity sonar and seismic blasts are significant contributors to noise pollution in coastal areas. Sonar (SOund Navigation And Ranging) is a technique used to detect objects underwater by emitting pulses of sound and analysing the returning echo. Military vessels, submarines, airplanes, and helicopters often use active sonar, which can reach extremely high volumes of up to 235 decibels. This level of noise can interfere with the echolocation abilities of marine mammals like whales and dolphins, which they use to communicate, navigate, feed, and find mates. The interference from sonar noise can lead to altered feeding behaviours, displacement of dolphin populations, and even mass strandings of whales on beaches.

Seismic blasts are another major source of noise pollution. In the context of ocean exploration, seismic surveys involve the use of powerful airguns that blast loud sounds towards the seafloor at regular intervals, such as every 10 or 16 seconds. These blasts are used to map the ocean floor and locate oil and natural gas deposits. The noise from these blasts can be extremely loud, exceeding 180 decibels, and can cause severe damage to the internal organs of marine creatures, including giant squid. Additionally, the frequent occurrence of these blasts can contribute to a chaotic and stressful underwater environment for marine life.

The impact of noise pollution from high-intensity sonar and seismic blasts extends beyond the immediate acoustic effects. The excessive noise interferes with the natural behaviours of marine animals, disrupting their communication, navigation, and feeding patterns. It can also cause physiological stress responses and impair their coordination and hearing abilities. In some cases, loud noises can lead to haemorrhaging in the heart and brain of certain species within a few hours of exposure.

Furthermore, noise pollution can result in direct injuries and fatalities among marine mammals. Whales and dolphins may panic and attempt to escape the source of the noise too quickly, leading to strandings or decompression sickness from surfacing too rapidly. The increased background noise in coastal waters also affects a variety of species, from tiny shrimp to larger marine mammals. As human activities in coastal regions continue to generate excessive noise, the peaceful marine environment becomes disrupted, posing challenges to the survival and reproductive success of many species.

Ocean acidification from absorption of carbon emissions

Ocean water is most polluted near coasts due to human activities along coastlines and far inland. Nonpoint source pollution, which occurs as a result of runoff from sources like septic tanks, vehicles, farms, and livestock ranches, is a significant contributor. Point source pollution, such as oil or chemical spills and discharge from faulty factories, also affects coastal areas. Additionally, plastic pollution, microplastics, and marine debris are prevalent in coastal areas, impacting marine life and the environment.

Now, let's focus on the topic of ocean acidification from the absorption of carbon emissions:

The ocean absorbs a significant portion of the carbon dioxide (CO2) released into the atmosphere, currently absorbing about 29-30% of global CO2 emissions. This absorption leads to ocean acidification, which is a growing environmental concern. Ocean acidification refers to the increase in the acidity of ocean waters due to the absorption of CO2. When CO2 is absorbed by seawater, it undergoes a series of chemical reactions, resulting in the formation of carbonic acid and an increased concentration of hydrogen ions, leading to a decrease in pH levels.

The impact of ocean acidification is far-reaching and has significant ecological and economic consequences. Ecologically, ocean acidification poses a threat to marine life, especially shellfish and other organisms that rely on carbonate ions to build their shells and survive. Species such as clams, mussels, crabs, and corals are directly affected by the changing chemistry of seawater. The increasing acidity also disrupts the sensory range of marine wildlife, impacting their foraging, mating, and other vital behaviors.

Economically, ocean acidification affects important sectors such as fisheries and tourism, with potential losses in the shellfish industry of over $400 million annually by 2100. Coastal communities that depend on shellfish and other marine resources for their livelihood and cultural identity are particularly vulnerable. Additionally, ocean acidification hinders the ocean's ability to absorb CO2, exacerbating the challenges posed by climate change.

To address ocean acidification, it is crucial to reduce carbon emissions from the burning of fossil fuels and implement adaptation solutions. Researchers are exploring ways to minimize the impact of ocean acidification on oyster hatcheries and studying the potential of growing seaweed to slow down this process. The understanding of ocean acidification and its effects is an active area of research, with organizations like the IAEA's Ocean Acidification International Coordination Centre (OA-ICC) dedicated to facilitating collaboration and communication on this global issue.

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