What is Ocean Pollution?
Oceans are the largest water bodies on the planet Earth. Over the last few decades, surplus human activities have severely affected marine life on the Earth’s oceans. Ocean pollution, also known as marine pollution, is the spreading of harmful substances such as oil, plastic, industrial and agricultural waste and chemical particles into the ocean. Since oceans provide the home to wide variety of marine animals and plants, it is the responsibility of every citizen to play his or her part in making these oceans clean so that marine species can thrive for a long period of time.
Mining for materials such as copper and gold is a major source of contamination in the ocean. For example, copper is a major source of pollutant in the ocean and can interfere with the life cycles of numerous marine organisms and life.
According to National Geographic,
“Many ocean pollutants are released into the environment far upstream from coastlines. Nitrogen-rich fertilizers applied by farmers inland, for example, end up in local streams, rivers, and groundwater and are eventually deposited in estuaries, bays, and deltas. These excess nutrients can spawn massive blooms of algae that rob the water of oxygen, leaving areas where little or no marine life can exist.”
Various Causes of Ocean Pollution
There are various ways in which pollution enters the ocean. Some of them are:
1. Sewage
Pollution can enter the ocean directly. Sewage or polluting substances flow through sewage, rivers, or drainages directly into the ocean. This is often how minerals and substances from mining camps find their way into the ocean.
The release of other chemical nutrients into the ocean’s ecosystem leads to reductions in oxygen levels, the decay of plant life, a severe decline in the quality of the seawater itself. As a result, all levels of oceanic life, plants and animals, are highly affected.
2. Toxic Chemicals From Industries
Industrial and agricultural waste is another most common form of wastes that are directly discharged into the oceans, resulting in ocean pollution. The dumping of toxic liquids in the ocean directly affects the marine life as they are considered hazardous and secondly, they raise the temperature of the ocean, known as thermal pollution, as the temperature of these liquids is quite high. Animals and plants that cannot survive at higher temperatures eventually perish.
3. Land Runoff
Land runoff is another source of pollution in the ocean. This occurs when water infiltrates the soil to its maximum extent and the excess water from rain, flooding or melting flows over the land and into the ocean.
Often, this water picks up man-made, harmful contaminants that pollute the ocean, including fertilizers, petroleum, pesticides and other forms of soil contaminants. Fertilizers and waste from land animals and humans can be a huge detriment to the ocean by creating dead zones.
4. Large Scale Oil Spills
Ship pollution is a huge source of ocean pollution, the most devastating effect of which is oil spills. Crude oil lasts for years in the sea and is extremely toxic to marine life, often suffocating marine animals to death once it entraps them. Crude oil is also extremely difficult to clean up, unfortunately meaning that when it is split; it is usually there to stay.
In addition, many ships lose thousands of crates each year due to storms, emergencies, and accidents. This causes noise pollution (excessive, unexpected noise that interrupts the balance of life, most often caused by modes of transportation), excessive algae, and ballast water. Often times, other species can also invade an ecosystem and do harm to it by interrupting the life cycles of other organisms, causing a clash of nature that has already been damaged by the overflow of pollution.
5. Ocean Mining
Ocean mining in the deep sea is yet another source of ocean pollution. Ocean mining sites drilling for silver, gold, copper, cobalt, and zinc create sulfide deposits up to three and a half thousand meters down into the ocean.
While we have yet the gathering of scientific evidence to fully explain the harsh environmental impacts of deep-sea mining, we do have a general idea that deep sea mining causes damage to the lowest levels of the ocean and increase the toxicity of the region. This permanent damage dealt also causes leaking, corrosion and oil spills that only drastically further hinder the ecosystem of the region.
6. Littering
Pollution from the atmosphere is, believe it or not, a huge source of ocean pollution. This occurs when objects that are far inland are blown by the wind over long distances and end up in the ocean. These objects can be anything from natural things like dust and sand to man-made objects such as debris and trash. Most debris, especially plastic debris, cannot decompose and remains suspended in the ocean’s current for years.
Animals can become snagged on the plastic or mistake it for food, slowly killing them over a long period of time. Animals who are most often the victims of plastic debrisinclude turtles, dolphins, fish, sharks, crabs, sea birds, and crocodiles.
In addition, the temperature of the ocean is highly affected by carbon dioxide and climate changes, which impacts primarily the ecosystems and fish communities that live in the ocean. In particular, the rising levels of Co2 acidify the ocean in the form of acid rain.
Even though the ocean can absorb carbon dioxide that originates from the atmosphere, the carbon dioxide levels are steadily increasing and the ocean’s absorbing mechanisms, due to the rising of the ocean’s temperatures, are unable to keep up with the pace.
Devastating Effects of Ocean Pollution
1. Effect of Toxic Wastes on Marine Animals
The oil spill is dangerous to marine life in several ways. The oil spilled in the ocean could get on to the gills and feathers of marine animals, which makes it difficult for them to move or fly properly or feed their children. The long term effect on marine life can include cancer, failure in the reproductive system, behavioral changes, and even death.
2. Disruption to the Cycle of Coral Reefs
Oil spill floats on the surface of the water and prevents sunlight from reaching to marine plants and affects the process of photosynthesis. Skin irritation, eye irritation, lung and liver problems can impact marine life over a long period of time.
3. Depletes Oxygen Content in Water
Most of the debris in the ocean does not decompose and remain in the ocean for years. It uses oxygen as it degrades. As a result of this, oxygen levels go down. When oxygen levels go down, the chances of survival of marine animals like whales, turtles, sharks, dolphins, penguins for a long time also goes down.
4. Failure in the Reproductive System of Sea Animals
Industrial and agricultural wastes include various poisonous chemicals that are considered hazardous for marine life. Chemicals from pesticides can accumulate in the fatty tissue of animals, leading to failure in their reproductive system.
5. Effect on Food Chain
Chemicals used in industries and agriculture get washed into the rivers and from there are carried into the oceans. These chemicals do not get dissolved and sink at the bottom of the ocean. Small animals ingest these chemicals and are later eaten by large animals, which then affects the whole food chain.
6. Affects Human Health
Animals from impacted food chain are then eaten by humans which affects their health as toxins from these contaminated animals get deposited in the tissues of people and can lead to cancer, birth defects or long term health problems.
Marine pollution occurs when harmful effects result from the entry into the ocean of chemicals, particles, industrial, agricultural and residential waste, noise, or the spread of invasive organisms. Eighty percent of marine pollution comes from land. Air pollution is also a contributing factor by carrying off pesticides or dirt into the ocean. Land and air pollution have proven to be harmful to marine life and its habitats.[1]
The pollution often comes from nonpoint sources such as agricultural runoff, wind-blown debris, and dust. Pollution in large bodies of water can be aggravated by physical phenomena like wind driven Langmuir circulation and their biological effects. Nutrient pollution, a form of water pollution, refers to contamination by excessive inputs of nutrients. It is a primary cause of eutrophication of surface waters, in which excess nutrients, usually nitrates or phosphates, stimulate algae growth. Many potentially toxic chemicals adhere to tiny particles which are then taken up by plankton and benthic animals, most of which are either deposit feeders or filter feeders. In this way, the toxins are concentrated upward within ocean food chains. Many particles combine chemically in a manner highly depletive of oxygen, causing estuaries to become anoxic.
When pesticides are incorporated into the marine ecosystem, they quickly become absorbed into marine food webs. Once in the food webs, these pesticides can cause mutations, as well as diseases, which can be harmful to humans as well as the entire food web. Toxic metals can also be introduced into marine food webs. These can cause a change to tissue matter, biochemistry, behaviour, reproduction, and suppress growth in marine life. Also, many animal feeds have a high fish meal or fish hydrolysatecontent. In this way, marine toxins can be transferred to land animals, and appear later in meat and dairy products.
In order to protect the ocean from marine pollution, policies have been developed internationally. There are different ways for the ocean to get polluted, therefore there have been multiple laws, policies, and treaties put into place throughout history.
History[edit]
Although marine pollution has a long history, significant international laws to counter it were not enacted until the twentieth century. Marine pollution was a concern during several United Nations Conventions on the Law of the Seabeginning in the 1950s. Most scientists believed that the oceans were so vast that they had unlimited ability to dilute, and thus render pollution harmless.
In the late 1950s and early 1960s, there were several controversies about dumping radioactive waste off the coasts of the United States by companies licensed by the Atomic Energy Commission, into the Irish Sea from the British reprocessing facility at Windscale, and into the Mediterranean Sea by the French Commissariat à l'Energie Atomique. After the Mediterranean Sea controversy, for example, Jacques Cousteau became a worldwide figure in the campaign to stop marine pollution. Marine pollution made further international headlines after the 1967 crash of the oil tanker Torrey Canyon, and after the 1969 Santa Barbara oil spill off the coast of California.
Marine pollution was a major area of discussion during the 1972 United Nations Conference on the Human Environment, held in Stockholm. That year also saw the signing of the Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter, sometimes called the London Convention. The London Convention did not ban marine pollution, but it established black and gray lists for substances to be banned (black) or regulated by national authorities (gray). Cyanide and high-level radioactive waste, for example, were put on the black list. The London Convention applied only to waste dumped from ships, and thus did nothing to regulate waste discharged as liquids from pipelines.[2]
Pathways of pollution[edit]
There are many ways to categorize and examine the inputs of pollution into marine ecosystems. Patin (n.d.) notes that generally there are three main types of inputs of pollution into the ocean: direct discharge of waste into the oceans, runoff into the waters due to rain, and pollutants released from the atmosphere.[3]
One common path of entry by contaminants to the sea are rivers. The evaporation of water from oceans exceeds precipitation. The balance is restored by rain over the continents entering rivers and then being returned to the sea. The Hudson in New York State and the Raritan in New Jersey, which empty at the northern and southern ends of Staten Island, are a source of mercury contamination of zooplankton(copepods) in the open ocean. The highest concentration in the filter-feeding copepods is not at the mouths of these rivers but 70 miles (110 km) south, nearer Atlantic City, because water flows close to the coast. It takes a few days before toxins are taken up by the plankton.[4]
Pollution is often classed as point source or nonpoint source pollution. Point source pollution occurs when there is a single, identifiable, localized source of the pollution. An example is directly discharging sewage and industrial waste into the ocean. Pollution such as this occurs particularly in developing nations. Nonpoint source pollution occurs when the pollution comes from ill-defined and diffuse sources. These can be difficult to regulate. Agricultural runoffand wind blown debris are prime examples.
Direct discharge[edit]
Pollutants enter rivers and the sea directly from urban sewerage and industrial waste discharges, sometimes in the form of hazardous and toxic wastes, or in the form of plastics.
In a study published by Science, Jambeck et al (2015) estimated that the 10 largest emitters of oceanic plastic pollution worldwide are, from the most to the least, China, Indonesia, Philippines, Vietnam, Sri Lanka, Thailand, Egypt, Malaysia, Nigeria, and Bangladesh.[5]
Inland mining for copper, gold, etc., is another source of marine pollution. Most of the pollution is simply soil, which ends up in rivers flowing to the sea. However, some minerals discharged in the course of the mining can cause problems, such as copper, a common industrial pollutant, which can interfere with the life history and development of coral polyps.[6] Mining has a poor environmental track record. For example, according to the United States Environmental Protection Agency, mining has contaminated portions of the headwaters of over 40% of watersheds in the western continental US.[7] Much of this pollution finishes up in the sea.
Land runoff[edit]
Surface runoff from farming, as well as urban runoff and runoff from the construction of roads, buildings, ports, channels, and harbours, can carry soil and particles laden with carbon, nitrogen, phosphorus, and minerals. This nutrient-rich water can cause fleshy algae and phytoplankton to thrive in coastal areas; known as algal blooms, which have the potential to create hypoxic conditions by using all available oxygen. In the coast of southwest Florida, harmful algal blooms have existed for over 100 years.[8] These algal blooms have been a cause of species of fish, turtles, dolphins, and shrimp to die and cause harmful effects on humans who swim in the water.[8]
Polluted runoff from roads and highways can be a significant source of water pollution in coastal areas. About 75% of the toxic chemicals that flow into Puget Sound are carried by stormwater that runs off paved roads and driveways, rooftops, yards and other developed land.[9] In California, there are many rainstorms that runoff into the ocean. These rainstorms occur from October to March, and these runoff waters contain petroleum, heavy metals, pollutants from emissions, etc.[10]
In China, there is a large coastal population that pollutes the ocean through land runoff. This includes sewage discharge and pollution from urbanization and land use. In 2001, more than 66,795 mi² of the Chinese coastal ocean waters were rated less than Class I of the Sea Water Quality Standard of China.[11] Much of this pollution came from Ag, Cu, Cd, Pb, As, DDT, PCBs, etc., which occurred from contamination through land runoff.[11]
Ship pollution[edit]
Ships can pollute waterways and oceans in many ways. Oil spills can have devastating effects. While being toxic to marine life, polycyclic aromatic hydrocarbons (PAHs), found in crude oil, are very difficult to clean up, and last for years in the sediment and marine environment.[12][page needed]
Oil spills are probably the most emotive of marine pollution events. However, while a tanker wreck may result in extensive newspaper headlines, much of the oil in the world's seas comes from other smaller sources, such as tankers discharging ballast water from oil tanks used on return ships, leaking pipelines or engine oil disposed of down sewers.[13][page needed]
Discharge of cargo residues from bulk carriers can pollute ports, waterways, and oceans. In many instances vessels intentionally discharge illegal wastes despite foreign and domestic regulation prohibiting such actions. An absence of national standards provides an incentive for some cruise liners to dump waste in places where the penalties are inadequate.[14] It has been estimated that container ships lose over 10,000 containers at sea each year (usually during storms).[15] Ships also create noise pollution that disturbs natural wildlife, and water from ballast tanks can spread harmful algae and other invasive species.[16]
Ballast water taken up at sea and released in port is a major source of unwanted exotic marine life. The invasive freshwater zebra mussels, native to the Black, Caspian, and Azov seas, were probably transported to the Great Lakes via ballast water from a transoceanic vessel.[17] Meinesz believes that one of the worst cases of a single invasive species causing harm to an ecosystem can be attributed to a seemingly harmless jellyfish. Mnemiopsis leidyi, a species of comb jellyfish that spread so it now inhabits estuaries in many parts of the world, was first introduced in 1982, and thought to have been transported to the Black Sea in a ship's ballast water. The population of the jellyfish grew exponentially and, by 1988, it was wreaking havoc upon the local fishing industry. "The anchovy catch fell from 204,000 tons in 1984 to 200 tons in 1993; sprat from 24,600 tons in 1984 to 12,000 tons in 1993; horse mackerel from 4,000 tons in 1984 to zero in 1993."[16] Now that the jellyfish have exhausted the zooplankton, including fish larvae, their numbers have fallen dramatically, yet they continue to maintain a stranglehold on the ecosystem.
Invasive species can take over once occupied areas, facilitate the spread of new diseases, introduce new genetic material, alter underwater seascapes, and jeopardize the ability of native species to obtain food. Invasive species are responsible for about $138 billion annually in lost revenue and management costs in the US alone.[18]
Atmospheric pollution[edit]
Another pathway of pollution occurs through the atmosphere. Wind-blown dust and debris, including plastic bags, are blown seaward from landfills and other areas. Dust from the Sahara moving around the southern periphery of the subtropical ridge moves into the Caribbean and Florida during the warm season as the ridge builds and moves northward through the subtropical Atlantic. Dust can also be attributed to a global transport from the Gobi and Taklamakan deserts across Korea, Japan, and the Northern Pacific to the Hawaiian Islands.[20]
Since 1970, dust outbreaks have worsened due to periods of drought in Africa. There is a large variability in dust transport to the Caribbean and Florida from year to year;[21] however, the flux is greater during positive phases of the North Atlantic Oscillation.[22] The USGS links dust events to a decline in the health of coral reefs across the Caribbean and Florida, primarily since the 1970s.[23]
Climate change is raising ocean temperatures[24] and raising levels of carbon dioxide in the atmosphere. These rising levels of carbon dioxide are acidifying the oceans.[25] This, in turn, is altering aquatic ecosystems and modifying fish distributions,[26] with impacts on the sustainability of fisheries and the livelihoods of the communities that depend on them. Healthy ocean ecosystems are also important for the mitigation of climate change.[27]
Deep sea mining[edit]
Deep sea mining is a relatively new mineral retrieval process that takes place on the ocean floor. Ocean mining sites are usually around large areas of polymetallic nodules or active and extinct hydrothermal vents at about 1,400 – 3,700 meters below the ocean's surface.[28] The vents create sulfide deposits, which contain precious metals such as silver, gold, copper, manganese, cobalt, and zinc.[29][30] The deposits are mined using either hydraulic pumps or bucket systems that take ore to the surface to be processed. As with all mining operations, deep sea mining raises questions about environmental damages to the surrounding areas.
Because deep sea mining is a relatively new field, the complete consequences of full-scale mining operations are unknown. However, experts are certain that removal of parts of the sea floor will result in disturbances to the benthic layer, increased toxicity of the water column, and sediment plumes from tailings.[29] Removing parts of the sea floor disturbs the habitat of benthic organisms, possibly, depending on the type of mining and location, causing permanent disturbances.[28] Aside from direct impact of mining the area, leakage, spills, and corrosion would alter the mining area's chemical makeup.
Among the impacts of deep sea mining, sediment plumes could have the greatest impact. Plumes are caused when the tailings from mining (usually fine particles) are dumped back into the ocean, creating a cloud of particles floating in the water. Two types of plumes occur: near-bottom plumes and surface plumes.[28] Near-bottom plumes occur when the tailings are pumped back down to the mining site. The floating particles increase the turbidity, or cloudiness, of the water, clogging filter-feeding apparatuses used by benthic organisms.[31]Surface plumes cause a more serious problem. Depending on the size of the particles and water currents the plumes could spread over vast areas.[28][32] The plumes could impact zooplankton and light penetration, in turn affecting the food web of the area.[28][32]
Types of pollution[edit]
Acidification[edit]
The oceans are normally a natural carbon sink, absorbing carbon dioxide from the atmosphere. Because the levels of atmospheric carbon dioxide are increasing, the oceans are becoming more acidic.[34][35] The potential consequences of ocean acidification are not fully understood, but there are concerns that structures made of calcium carbonate may become vulnerable to dissolution, affecting corals and the ability of shellfish to form shells.[36]
Oceans and coastal ecosystems play an important role in the global carbon cycle and have removed about 25% of the carbon dioxide emitted by human activities between 2000 and 2007 and about half the anthropogenic CO2 released since the start of the industrial revolution. Rising ocean temperatures and ocean acidification means that the capacity of the ocean carbon sink will gradually get weaker,[37]giving rise to global concerns expressed in the Monaco[38] and Manado[39] Declarations.
A report from NOAA scientists published in the journal Science in May 2008 found that large amounts of relatively acidified water are upwelling to within four miles of the Pacific continental shelf area of North America. This area is a critical zone where most local marine life lives or is born. While the paper dealt only with areas from Vancouver to northern California, other continental shelf areas may be experiencing similar effects.[40]
A related issue is the methane clathrate reservoirs found under sediments on the ocean floors. These trap large amounts of the greenhouse gas methane, which ocean warming has the potential to release. In 2004 the global inventory of ocean methane clathrates was estimated to occupy between one and five million cubic kilometres.[41] If all these clathrates were to be spread uniformly across the ocean floor, this would translate to a thickness between three and fourteen metres.[42] This estimate corresponds to 500–2500 gigatonnes carbon (Gt C), and can be compared with the 5000 Gt C estimated for all other fossil fuel reserves.[41][43]
Eutrophication[edit]
Eutrophication is an increase in chemical nutrients, typically compounds containing nitrogen or phosphorus, in an ecosystem. It can result in an increase in the ecosystem's primary productivity (excessive plant growth and decay), and further effects including lack of oxygen and severe reductions in water quality, fish, and other animal populations.
The biggest culprit are rivers that empty into the ocean, and with it the many chemicals used as fertilizers in agriculture as well as waste from livestock and humans. An excess of oxygen-depleting chemicals in the water can lead to hypoxia and the creation of a dead zone.[4]
Estuaries tend to be naturally eutrophic because land-derived nutrients are concentrated where runoff enters the marine environment in a confined channel. The World Resources Institute has identified 375 hypoxic coastal zones around the world, concentrated in coastal areas in Western Europe, the Eastern and Southern coasts of the US, and East Asia, particularly in Japan.[44] In the ocean, there are frequent red tide algae blooms[45] that kill fish and marine mammals and cause respiratory problems in humans and some domestic animals when the blooms reach close to shore.
In addition to land runoff, atmospheric anthropogenic fixed nitrogen can enter the open ocean. A study in 2008 found that this could account for around one third of the ocean's external (non-recycled) nitrogen supply and up to three per cent of the annual new marine biological production.[46] It has been suggested that accumulating reactive nitrogen in the environment may have consequences as serious as putting carbon dioxide in the atmosphere.[47]
One proposed solution to eutrophication in estuaries is to restore shellfish populations, such as oysters. Oyster reefs remove nitrogen from the water column and filter out suspended solids, subsequently reducing the likelihood or extent of harmful algal blooms or anoxic conditions.[48] Filter feeding activity is considered beneficial to water quality[49] by controlling phytoplankton density and sequestering nutrients, which can be removed from the system through shellfish harvest, buried in the sediments, or lost through denitrification.[50][51]Foundational work toward the idea of improving marine water quality through shellfish cultivation to was conducted by Odd Lindahl et al., using mussels in Sweden.[52]
Plastic debris[edit]
Marine debris is mainly discarded human rubbish which floats on, or is suspended in the ocean. Eighty percent of marine debris is plastic – a component that has been rapidly accumulating since the end of World War II.[53] The mass of plastic in the oceans may be as high as 100,000,000 tonnes (98,000,000 long tons; 110,000,000 short tons).[54]
In a study published by Environmental Science & Technology, Schmidt et al (2017) calculated that the Yangtze, Indus, Yellow River, Hai River, Nile, Ganges, Pearl River, Amur, Niger, and the Mekong "transport 88–95% of the global [plastics] load into the sea."[55][56]
Discarded plastic bags, six pack rings, cigarette butts and other forms of plastic waste which finish up in the ocean present dangers to wildlife and fisheries.[57] Aquatic life can be threatened through entanglement, suffocation, and ingestion.[58][59][60] Fishing nets, usually made of plastic, can be left or lost in the ocean by fishermen. Known as ghost nets, these entangle fish, dolphins, sea turtles, sharks, dugongs, crocodiles, seabirds, crabs, and other creatures, restricting movement, causing starvation, laceration, infection, and, in those that need to return to the surface to breathe, suffocation.[61]
Many animals that live on or in the sea consume flotsam by mistake, as it often looks similar to their natural prey.[62] Plastic debris, when bulky or tangled, is difficult to pass, and may become permanently lodged in the digestive tracts of these animals. Especially when evolutionary adaptions make it impossible for the likes of turtles to reject plastic bags, which resemble jellyfish when immersed in water, as they have a system in their throat to stop slippery foods from otherwise escaping.[63] Thereby blocking the passage of food and causing death through starvation or infection.[64][65]
Plastics accumulate because they don't biodegrade in the way many other substances do. They will photodegrade on exposure to the sun, but they do so properly only under dry conditions, and water inhibits this process.[66] In marine environments, photodegraded plastic disintegrates into ever-smaller pieces while remaining polymers, even down to the molecular level. When floating plastic particles photodegrade down to zooplankton sizes, jellyfish attempt to consume them, and in this way the plastic enters the ocean food chain.[67][68]
Many of these long-lasting pieces end up in the stomachs of marine birds and animals,[69] including sea turtles, and black-footed albatross.[70] In a 2008 Pacific Gyre voyage, Algalita Marine Research Foundation researchers began finding that fish are ingesting plastic fragments and debris. Of the 672 fish caught during that voyage, 35% had ingested plastic pieces.[71]
Plastic debris tends to accumulate at the centre of ocean gyres. The North Pacific Gyre, for example, has collected the so-called "Great Pacific Garbage Patch", which is now estimated to be one to twenty times the size of Texas (approximately from 700,000 to 15,000,000 square kilometers). There could be as much plastic as fish in the sea.[72] It has a very high level of plastic particulate suspended in the upper water column. In samples taken in 1999, the mass of plastic exceeded that of zooplankton (the dominant animal life in the area) by a factor of six.[53][73]
Midway Atoll, in common with all the Hawaiian Islands, receives substantial amounts of debris from the garbage patch. Ninety percent plastic, this debris accumulates on the beaches of Midway where it becomes a hazard to the bird population of the island. Midway Atoll is home to two-thirds (1.5 million) of the global population of Laysan albatross.[75] Nearly all of these albatross have plastic in their digestive system[76] and one-third of their chicks die.[77]
Toxic additives used in the manufacture of plastic materials can leach out into their surroundings when exposed to water. Waterborne hydrophobic pollutants collect and magnify on the surface of plastic debris,[54] thus making plastic far more deadly in the ocean than it would be on land.[53] Hydrophobic contaminants are also known to bioaccumulate in fatty tissues, biomagnifying up the food chain and putting pressure on apex predators. Some plastic additives are known to disrupt the endocrine system when consumed, others can suppress the immune system or decrease reproductive rates.[73]
Floating debris can also absorb persistent organic pollutants from seawater, including PCBs, DDT, and PAHs.[78] Aside from toxic effects,[79]when ingested some of these affect animal brain cells similarly to estradiol, causing hormone disruption in the affected wildlife.[70] Saido, a chemist with the College of Pharmacy, conducted a study in Nihon University, Chiba, Japan, that discovered, when plastics eventually decompose, they produce potentially toxic bisphenol A (BPA) and PS oligomer into the water.[80] These toxins are believed to bring harm to the marine life living in the area.
A growing concern regarding plastic pollution in the marine ecosystem is the use of microplastics. Microplastics are little beads of plastic less than 5 millimeters wide, and they are commonly found in hand soaps, face cleansers, and other exfoliators. When these products are used, the microplastics go through the water filtration system and into the ocean, but because of their small size they are likely to escape capture by the preliminary treatment screens on wastewater plants.[81] These beads are harmful to the organisms in the ocean, especially filter feeders, because they can easily ingest the plastic and become sick. The microplastics are such a concern because it is difficult to clean them up due to their size, so humans can try to avoid using these harmful plastics by purchasing products that use environmentally safe exfoliates.
Toxins[edit]
Apart from plastics, there are particular problems with other toxins that do not disintegrate rapidly in the marine environment. Examples of persistent toxins are PCBs, DDT, TBT, pesticides, furans, dioxins, phenols, and radioactive waste. Heavy metals are metallic chemical elements that have a relatively high density and are toxic or poisonous at low concentrations. Examples are mercury, lead, nickel, arsenic, and cadmium. Such toxins can accumulate in the tissues of many species of aquatic life in a process called bioaccumulation. They are also known to accumulate in benthic environments, such as estuaries and bay muds: a geological record of human activities of the last century.
- Specific examples
- Chinese and Russian industrial pollution such as phenols and heavy metals in the Amur River have devastated fish stocks and damaged its estuary soil.[82]
- Wabamun Lake in Alberta, Canada, once the best whitefish lake in the area, now has unacceptable levels of heavy metals in its sediment and fish.
- Acute and chronic pollution events have been shown to impact southern California kelp forests, though the intensity of the impact seems to depend on both the nature of the contaminants and duration of exposure.[83][84][85][86][87]
- Due to their high position in the food chain and the subsequent accumulation of heavy metals from their diet, mercury levels can be high in larger species such as bluefin and albacore. As a result, in March 2004 the United States FDA issued guidelines recommending that pregnant women, nursing mothers and children limit their intake of tuna and other types of predatory fish.[88]
- Some shellfish and crabs can survive polluted environments, accumulating heavy metals or toxins in their tissues. For example, mitten crabs have a remarkable ability to survive in highly modified aquatic habitats, including polluted waters.[89] The farming and harvesting of such species needs careful management if they are to be used as a food.[90][91]
- Surface runoff of pesticides can alter the gender of fish species genetically, transforming male into female fish.[92]
- Heavy metals enter the environment through oil spills – such as the Prestige oil spill on the Galician coast and Gulf of Mexico which unleashed an estimated 3.19 million barrels of oil[93] – or from other natural or anthropogenic sources.
- In 2005, the 'Ndrangheta, an Italian mafia syndicate, was accused of sinking at least 30 ships loaded with toxic waste, much of it radioactive. This has led to widespread investigations into radioactive waste disposal rackets.[94]
- Since the end of World War II, various nations, including the Soviet Union, the United Kingdom, the United States, and Germany, have disposed of chemical weapons in the Baltic Sea, raising concerns of environmental contamination.[95][96]
- The Fukushima Daiichi nuclear disaster in 2011 caused radioactive toxins from the damaged power plant to leak into the air and ocean. There are still many isotopes in the ocean, which directly affects the benthic food web and also affects the whole food chain. The concentration of 137Cs in the bottom sediment that was contaminated by water with high concentrations in April–May 2011 remains quite high and is showing signs of very slow decrease with time.[97]
Underwater noise[edit]
Marine life can be susceptible to noise or the sound pollution from sources such as passing ships, oil exploration seismic surveys, and naval low-frequency active sonar. Sound travels more rapidly and over larger distances in the sea than in the atmosphere. Marine animals, such as cetaceans, often have weak eyesight, and live in a world largely defined by acoustic information. This applies also to many deeper sea fish, who live in a world of darkness.[98] Between 1950 and 1975, ambient noise at one location in the Pacific Ocean increased by about ten decibels (that is a tenfold increase in intensity).[99]
Noise also makes species communicate louder, which is called the Lombard vocal response.[100] Whale songs are longer when submarine-detectors are on.[101] If creatures don't "speak" loud enough, their voice can be masked by anthropogenic sounds. These unheard voices might be warnings, finding of prey, or preparations of net-bubbling. When one species begins speaking louder, it will mask other species voices, causing the whole ecosystem to eventually speak louder.[102]
According to the oceanographer Sylvia Earle, "Undersea noise pollution is like the death of a thousand cuts. Each sound in itself may not be a matter of critical concern, but taken all together, the noise from shipping, seismic surveys, and military activity is creating a totally different environment than existed even 50 years ago. That high level of noise is bound to have a hard, sweeping impact on life in the sea."[103]
Noise from ships and human activity can damage Cnidarians and Ctenophora, which are very important organisms in the marine ecosystem. They promote high diversity and they are used as models for ecology and biology because of their simple structures. When there is underwater noise, the vibrations in the water damage the cilia hairs in the Coelenterates. In a study, the organisms were exposed to sound waves for different numbers of times and the results showed that damaged hair cells were extruded or missing or presented bent, flaccid or missed kinocilia and stereocilia.[104]
Adaptation and mitigation[edit]
Much anthropogenic pollution ends up in the ocean. The 2011 edition of the United Nations Environment Programme Year Book identifies as the main emerging environmental issues the loss to the oceans of massive amounts of phosphorus, "a valuable fertilizer needed to feed a growing global population", and the impact billions of pieces of plastic waste are having globally on the health of marine environments.[105]
Bjorn Jennssen (2003) notes in his article, "Anthropogenic pollution may reduce biodiversity and productivity of marine ecosystems, resulting in reduction and depletion of human marine food resources".[106] There are two ways the overall level of this pollution can be mitigated: either the human population is reduced, or a way is found to reduce the ecological footprint left behind by the average human. If the second way is not adopted, then the first way may be imposed as the world ecosystems falter.
The second way is for humans, individually, to pollute less. That requires social and political will, together with a shift in awareness so more people respect the environment and are less disposed to abuse it.[107] At an operational level, regulations, and international government participation is needed.[108] It is often very difficult to regulate marine pollution because pollution spreads over international barriers, thus making regulations hard to create as well as enforce.[109]
Without appropriate awareness of marine pollution, the necessary global will to effectively address the issues may prove inadequate. Balanced information on the sources and harmful effects of marine pollution need to become part of general public awareness, and ongoing research is required to fully establish, and keep current, the scope of the issues. As expressed in Daoji and Dag's research,[110] one of the reasons why environmental concern is lacking among the Chinese is because the public awareness is low and therefore should be targeted.
The amount of awareness on marine pollution is vital to the support of keeping the prevention of trash from entering waterways and ending up in our oceans. The EPA reports that in 2014 Americans generated about 258 million tons of waste, and only a third was recycled or composted. In 2015, there was over 8 million tons of plastic that made it into the ocean. The Ocean Conservancy reported that China, Indonesia, Philippines, Thailand, and Vietnam dump more plastic in the sea than all other countries combined.[111] Through more sustainable packing this could lead to; eliminating toxic constituents, using fewer materials, making more readily available recyclable plastic. However, awareness can only take these initiatives so far. The most abundant plastic is PET (Polyethylene terephthalate) and is the most resistant to biodegradables. Researchers have been making great strides in combating this problem. In one way has been by adding a special polymer called a tetrablock copolymer. The tetrablock copolymer acts as a laminate between the PE and iPP which enables for an easier breakdown but still be tough. Through more awareness, individuals will become more cognizant of their carbon footprints. Also, from research and technology, more strides can be made to aid in the plastic pollution problem.[112][113]
In 2018 a survey of Global Oceanic Environmental Survey (GOES) Foundation find that the ecosystem in seas and oceans can collapse in the next 25 years what would fail the terrestrial ecosystem and end the life on earth as we know them. The main causes: Plastic pollution, Ocean acidification, Ocean pollution. For prevent that scenario from happen, we need a total single use plastic ban, ban on wood burning, planting as many trees as possible, " pollution-free recycling of electronics and by 2030 all industries to be zero toxic discharge." "special protection and perservation of peat bogs, wetlands, marshlands and mangrove swamps to ensure carbon dioxide is absorbed from the atmosphere.[114][115]"
Laws and policies[edit]
- In 1948, Harry Truman signed a law formerly known as the Federal Water Pollution Control Act[116] that allowed the federal government to control marine pollution in United States of America.
- In 1972, the Marine Protection, Research, and Sanctuaries Act of 1972 was passed by the Council on Environmental Quality which controls ocean dumping.[117][117]
- In 1973 and 1978, MARPOL 73/78 was a treaty written to control vessel pollution, especially regarding oil. In 1983, the International Convention for the Prevention of Pollution from Ships enforced the MARPOL 73/78 treaty internationally.[118]
- The 1982 United Nations Convention on the Law of the Sea (UNCLOS) was established to protect the marine environment by governing states to control their pollution to the ocean. It put restrictions on the amount of toxins and pollutants that come from all ships internationally.[119]
What Causes Ocean Pollution?
Pollution is defined as the process of introducing harmful or poisonous substances into the natural environment. Ocean pollution is therefore defined as the introduction of toxic materials such as plastic, oil, chemicals, agricultural waste, and industrial waste into the ocean waters. There can be several causes of ocean pollution, but the leading causes include sewage, toxic chemicals from industries, nuclear waste, thermal pollution, plastics, acid rain, and oil spillage.
Sewage
Sewage is defined as the wastewater and its component excrements that are transported in the sewer system. Sewage is mostly comprised of the human waste from toilet flushing, dirty water from bathing and even animal waste. Most of the wastes find their way into the ocean waters through the sewer systems. Some of the substances that are in the sewage waste are harmful and contribute greatly to ocean pollution. These substances may cause serious health problems to the aquatic creatures once they consume them.
Industrial Chemicals
Another major pollutant is the chemicals from industries and from the fertilizers and other farm products that are carried by run-off water into the ocean waters. Many industries dump their waste materials and chemicals into the ocean waters. These chemicals pollute the ocean by altering the pH level of the waters. Most aquatic plants and animals cannot survive in adverse pH levels.
Nuclear Waste
Another major ocean pollutant is the nuclear waste, which is mostly produced from industrial, medical, and also scientific procedures that use radioactive material. The common industries that produce nuclear waste include power stations, the military, and the reprocessing plants. This radiation enters the food chain through kelp and plankton, and once the marine animals consume these plants they become contaminated.
Thermal Pollution
Thermal pollution is the lowering of water quality by any method that tends to change the water temperature. Thermal pollution occurs when power plants and manufacturing companies release hot water into the water streams and oceans and thus causing a change in temperature by raising the temperatures higher. The sudden change in temperature causes reduction in the oxygen supply and this greatly affects the ecosystem composition. Aquatic plants and other organisms that are adapted to a certain temperature range get killed abruptly by the sudden change in temperature by a process known as thermal shock.
Plastics
Plastic pollution mainly involves the accumulation plastic in the ocean waters and thus causing adverse effects on marine organisms. Marine organisms are affected by the plastics through direct ingestion of the plastic wastes and also through exposure to chemicals that are within the plastics.
Acid Rain
Acid rain is not a major cause of ocean pollution, but it also contributes to water pollution. Erupting volcanoes, fossil fuels, rotting vegetation, and nitrogen oxides when released into the atmosphere react with water and other substances in the air to form sulphuric and nitric acid. The wind blows these chemicals across the atmosphere, and when it rains, these chemicals find their way into the marine waters. Acid rain makes water acidic and thus destroys the marine life as most aquatic organisms cannot survive in acidic conditions.
Oil Spills
Oil spillage is another primary cause of ocean pollution in that the oil forms a layer on the water preventing oxygen circulation. Lack of oxygen in the ocean waters results in the destruction of marine life over a long period. Therefore, it is necessary to prevent these pollutants from entering the oceans to protect the marine animals and plants.
What Causes Ocean Pollution?
There can be several causes of ocean pollution, but the leading causes include sewage, toxic chemicals from industries, nuclear waste, thermal pollution, plastics, acid rain, and oil spillage.
What are the effects of marine pollution?
by Penna Sparrow
It is very difficult to account for all the marine life and schools of fishes found in the ocean due to the size of oceans and the number of organisms found in them. Even though there have been studies and many of these go scientifically unknown and unaccounted for though there has been concentrated studies and researches that have been done in small areas of the ocean along with few test groups.
There are over 46,000 pieces of plastic that are floating in every square mile of the ocean found near the Northeast coast of the United States, as per the journal Review of Research of the Marine Academy’s Oceanography. These plastics end up contributing to the death of 1,00,000 marine mammals and millions of sea birds every year. In a report of New York Times on one Galapagos Island there was a serious drop of a rare species of Iguana from 25,000 to 10,000 due to an oil spill that occurred off the coast of the island in the year 2001.
The president of the Marine Conservation Biology Institute, Elliott Norse discovered plastic in the stomachs of 300 Albatross chicks on Midway Island which is 1600 kms away from the nearest land area. There was a massive British petroleum oil spill in the Gulf of Mexico. This was covered by the Center for Biological Diversity for a year. They had made some exceptional observations. They had reported around 82,000 birds of 102 species were either harmed or killed in it. Adding to the death toll were 6,165 sea turtles, 25,900 marine mammals and uncountable number of fishes were there too. By 2010 these statistics reached up to 658 sea birds, 279 sea turtles, 36 sea mammals and countless fishes.
Effects of Marine Pollution
Disruption of Coral Reefs
The oil spill keeps floating on the surface of the water. This thick layer above the surface of the water prevents sunlight from reaching marine flora and fauna. This leads to serious consequences to plant life by cutting down the process of photosynthesis. There are health problems that arise from the prolonged effect of oil spills. These can be seen in the form of skin irritation, eye irritation, lung and liver problems have a worsening impact on the marine life.
Reproductive System failure of Marine animals
Industrial & agricultural wastes have many impurities in them which contains hazardous chemicals that are no lesser than poisons for the marine organisms. The chemicals from the chemical pesticides accumulate in the fat tissues of the animals and disrupt the reproductive system. These substances that accumulate in the organisms stay in them for a really long time.
Depletes Oxygen Content of the Ocean
It has been observed that most of the debris that is deposited in the ocean does not decompose easily and they has a long life cycle and remain in the ocean for years at a stretch. The worst consequence of this debris being in the ocean for so long is as they degenerate, they keep consuming more and more oxygen from the ocean water. This hampers the present oxygen content of the water and reduces the oxygen level to a very petty amount, barely sufficient to maintain the ocean ecology. The reduced levels of oxygen raises a question on the survival of marine animals and mammals like sharks, dolphins, penguins, whales and turtles and the rate of survival is deplorably reduced as well.
Effect on Food Chain
There are numerous chemicals that being used in the agricultural fields and as well as in the industries. These chemicals often get washed away and flow into the rivers. These rivers then carry them to the Oceans in turn. These chemicals are unable to dissolve into the ocean water and remain suspended. Then they slowly sink to the bottom of the ocean floor. These chemicals are then ingested by the many small animals that survive within the ocean environment. Then these small animals are eaten by larger animals and then gradually moving up the food chain these chemicals get bio-accumulated and manifest as serious problems.
Effects of Toxic Wastes
Oil spills causes havoc in the marine environment and gives rise to some serious troubles. The oil spilled in the ocean water gets into the feathers of sea birds and gills of marine animals. This jeopardises with their ability to move or fly properly and handicaps their ability to feed their young ones. The effects of this are evident is diseases like cancer, failure of the reproductive system or can even cause death.
Effects on Human Health
Animals that already under the threat and influence of the chemically influenced food chain are then eaten by the human beings as well. The toxins that are present within these animals are then transferred through the food chain into humans as well. The human beings get contaminated with these toxins as they get deposited in their tissues. These then result to cancer, birth defects or even long term health problems.
Our ocean and the array of species that call it home are succumbing to the poison of plastic. Examples abound, from the gray whale that died after stranding near Seattle in 2010 with more than 20 plastic bags, a golf ball, and other rubbish in its stomach to the harbor seal pup found dead on the Scottish island of Skye, its intestines fouled by a small piece of plastic wrapper.
According to the United Nations, at least 800 species worldwide are affected by marine debris, and as much as 80 percent of that litter is plastic. It is estimated that up to 13 million metric tons of plastic ends up in the ocean each year—the equivalent of a rubbish or garbage truck load’s worth every minute. Fish, seabirds, sea turtles, and marine mammals can become entangled in or ingest plastic debris, causing suffocation, starvation, and drowning. Humans are not immune to this threat: While plastics are estimated to take up to hundreds of years to fully decompose, some of them break down much quicker into tiny particles, which in turn end up in the seafood we eat.
The following photos help illustrate the extent of the ocean plastics problem.
Ocean Plastics
A sea turtle found in the Pacific Ocean had this debris in its stomach, according to The Ocean Cleanup, a foundation.
The Ocean Cleanup Foundation
Research indicates that half of sea turtles worldwide have ingested plastic. Some starve after doing so, mistakenly believing they have eaten enough because their stomachs are full. On many beaches, plastic pollution is so pervasive that it’s affecting turtles’ reproduction rates by altering the temperatures of the sand where incubation occurs.
A recent study found that sea turtles that ingest just 14 pieces of plastic have an increased risk of death. The young are especially at risk because they are not as selective as their elders about what they eat and tend to drift with currents, just as plastic does.
Plastics
A dead albatross chick found on Midway Atoll in the Pacific Ocean with plastic debris in its stomach.
U.S. Fish and Wildlife Service
Plastic waste kills up to a million seabirds a year. As with sea turtles, when seabirds ingest plastic, it takes up room in their stomachs, sometimes causing starvation. Many seabirds are found dead with their stomachs full of this waste. Scientists estimate that 60 percent of all seabird species have eaten pieces of plastic, a figure they predict will rise to 99 percent by 2050.
Ocean plastics
A dolphin with a plastic bag trailing from its fin swims in the Fernando de Noronha Archipelago in Brazil.
João Vianna
While dolphins are highly intelligent and thus unlikely to eat plastic, they are susceptible to contamination through prey that have ingested synthetic compounds.
Plastic in our oceans affects creatures large and small. From seabirds, whales, and dolphins, to tiny seahorses that live in coral reefs……
Ocean plastics
A seahorse wraps its tail around a plastic cotton swab near Sumbawa Island, Indonesia.
Courtesy of Justin Hofman
... and schools of fish that reside on those same reefs and nearby mangroves.
Ocean plastics
A plastic band restricts the growth of a blue-striped grunt fish in the Caribbean Sea.
Karen Doody/Stocktrek Images
Plastic waste can encourage the growth of pathogens in the ocean. According to a recent study, scientists concluded that corals that come into contact with plastic have an 89 percent chance of contracting disease, compared with a 4 percent likelihood for corals that do not.
Unless action is taken soon to address this urgent problem, scientists predict that the weight of ocean plastics will exceed the combined weight of all of the fish in the seas by 2050.
Simon Reddy directs The Pew Charitable Trusts’ efforts to prevent ocean plastics.
Marine pollution has been an ever-present problem since the advent of large-scale agricultural activity and industrialization. However, significant laws and regulations at an international level to tackle the problem came only in the mid-twentieth century. During United Nations Conventions on the Law of the Sea in the early 1950s, the various stakeholders come together to deliberate and formulate laws pertaining to marine pollution. Till mid-twentieth century the majority of the scientists maintained that oceans were vast enough to be able to dilute the amount of pollution being drained into them, thus, considering pollution harmless to the marine life.
Causes of Marine Pollution
The marine environment becomes polluted and contaminated through various sources and forms. Major sources of marine pollution are the inflow of chemicals, solid waste, discharge of radioactive elements, industrial and agricultural effluents, man-made sedimentation, oil spills, and many such factors. The majority portion of the marine pollution comes from the land that contributes to 80 percent of the marine pollution, air pollution also carries pesticides from farms and dust into the marine waters. Air and land pollution is a major contributor to the growing marine pollution that is not only hampering the aquatic ecology but also affecting the life on land. The non-point sources like wind-blown debris, agricultural runoff, and dust become the major source of pollution. Apart from these, factors like land runoff, direct discharge, atmospheric pollution, pollution caused by ships, and deep sea mining of natural resources contribute heavily.
Types of Marine Pollution
Eutrophication
When there is an excess of chemical nutrients mainly nitrates and phosphates in the water, it leads to eutrophication or nutrient pollution. Eutrophication decreases the level of oxygen, reduces the quality of water, makes the water inhabitable for fish, affects the breeding process within the marine life and increases the primary productivity of the marine ecosystem.
Acidification
Oceans act as a natural reservoir for absorbing the carbon dioxide from the Earth’s atmosphere. But, due to rising level of carbon dioxide in the atmosphere, the oceans across the world are becoming acidic in nature, as a consequence, it leads to acidification of oceans. Researches and scientists have not been able to uncover the potential damage ocean acidification may have on the Earth’s atmosphere. But, there is a strong concern that acidification might lead to dissolution of calcium carbonate structures, that can affect the shell formation in shellfish and also the corals.
Toxins
There are persistent toxins that do not get dissolved or disintegrate with the marine ecosystem rapidly. Toxins such as pesticides, DDT, PCBs, furans, TBT, radioactive waste, phenols, and dioxins get accumulated in the tissue cells of the marine lifeforms and lead to bioaccumulation hampering the life underwater and sometimes leads to a mutation in aquatic life forms.
Plastics
The ever-growing dependence of human population on plastic has filled the oceans and the land, it consists of 80 percent of the debris found in the oceans. Plastic dumped and found in the oceans are dangerous for the marine life forms and wildlife, as sometimes it strangles and chokes them to death. The rising levels of plastic dumps found in the oceans are suffocating, ingesting, and entangling the life underwater as well as above it.
Effects of Marine Pollution
The contamination of water by excessive nutrients is known as nutrient pollution, a type of water pollution that affects the life under water. When excess nutrients like nitrates or phosphates get dissolved with the water it causes the eutrophication of surface waters, as it stimulates the growth of algae due to excess nutrients. Most of Benthic animals and plankton are either filter feeders or deposit feeders take up the tiny particles that adhere to potentially toxic chemicals. In the ocean food chains, such toxins get concentrated upward. This makes estuaries anoxic as many particles combine chemically depletive of oxygen.
When the marine ecosystem absorbs the pesticides, they are incorporated into the food webs of the marine ecosystem. After getting dissolved in the marine food webs, these harmful pesticides causes mutations, and also results in diseases, which can damage the entire food web and cause harm to the humans. When toxic metals are dumped or flown into the oceans through drains, it engulfs within the marine food webs. It affects the biochemistry, reproduction process, can affect the tissue matter These can cause a change to tissue matter, biochemistry, behavior, reproduction, and suppress and alter the marine life’s growth. Marine toxins can be transferred to several animals feeding on the fish or fish hydrolysate as a meal, toxins are then transferred to dairy products and meat of these affected land animals.
Steps to Prevent Marine Pollution
Stop using plastic and littering garbage as they not only choke up the drains but also releases into the oceans.
Ensure that chemicals mentioned above are not used anywhere near the streams of water and try cutting down on the usage of such chemicals.
For farmers, they need to switch from chemical fertilizers and pesticides and move towards the usage of organic farming methods.
Use public transport and reduce the carbon footprint by taking small and substantial measures that will not help in reducing the pollution from the environment but will ensure a safe and healthy future for the upcoming generations.
Prevent from any oil or chemical spill in the oceans and if in case there is an oil or chemical spill near you volunteer and help in cleaning out the ocean water.
Volunteer or initiate beach clean up activities and spread awareness about the same in the nearby vicinity.