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Tuesday, May 21, 2019

Plastic pollution

From Wikipedia, the free encyclopedia

Plastic pollution in Ghana, 2018
 
Plastic pollution is the accumulation of plastic objects (e.g.: plastic bottles and much more) in the Earth's environment that adversely affects wildlife, wildlife habitat, and humans. Plastics that act as pollutants are categorized into micro-, meso-, or macro debris, based on size. Plastics are inexpensive and durable, and as a result levels of plastic production by humans are high. However, the chemical structure of most plastics renders them resistant to many natural processes of degradation and as a result they are slow to degrade. Together, these two factors have led to a high prominence of plastic pollution in the environment. 

Plastic pollution can afflict land, waterways and oceans. It is estimated that 1.1 to 8.8 million metric tons (MT) of plastic waste enters the ocean from costal communities each year. Living organisms, particularly marine animals, can be harmed either by mechanical effects, such as entanglement in plastic objects or problems related to ingestion of plastic waste, or through exposure to chemicals within plastics that interfere with their physiology. Humans are also affected by plastic pollution, such as through disruption of various hormonal mechanisms. 

As of 2018, about 380 million tons of plastic is produced worldwide each year. From the 1950s up to 2018, an estimated 6.3 billion tons of plastic has been produced worldwide, of which an estimated 9% has been recycled and another 12% has been incinerated. In the UK alone, more than 5 million tonnes of plastic are consumed each year, of which only an estimated one-quarter is recycled, with the remainder going to landfills. This large amount of plastic waste inevitably enters the environment, with studies suggesting that the bodies of 90% of seabirds contain plastic debris. In some areas there have been significant efforts to reduce the prominence of plastic pollution, through reducing plastic consumption and promoting plastic recycling.

Some researchers suggest that by 2050 there could be more plastic than fish in the oceans by weight.

Types of plastic debris

There are three major forms of plastic that contribute to plastic pollution: microplastics as well as mega- and macro-plastics. Mega- and micro plastics have accumulated in highest densities in the Northern Hemisphere, concentrated around urban centers and water fronts. Plastic can be found off the coast of some islands because of currents carrying the debris. Both mega- and macro-plastics are found in packaging, footwear, and other domestic items that have been washed off of ships or discarded in landfills. Fishing-related items are more likely to be found around remote islands. These may also be referred to as micro-, meso-, and macro debris. 

Plastic debris is categorized as either primary or secondary. Primary plastics are in their original form when collected. Examples of these would be bottle caps, cigarette butts, and microbeads. Secondary plastics, on the other hand, account for smaller plastics that have resulted from the degradation of primary plastics.

Microdebris

Microdebris are plastic pieces between 2 mm and 5 mm in size. Plastic debris that starts off as meso- or macrodebris can become microdebris through degradation and collisions that break it down into smaller pieces. Microdebris is more commonly referred to as nurdles. Nurdles are recycled to make new plastic items, but they easily end up released into the environment during production because of their small size. They often end up in ocean waters through rivers and streams. Microdebris that come from cleaning and cosmetic products are also referred to as scrubbers. Because microdebris and scrubbers are so small in size, filter-feeding organisms often consume them.

Primary microplastics, a type of microdebris, known as Nurdles enter the ocean by means of spills during transportation or from land based sources. These micro-plastics can accumulate in the oceans and allow for the accumulation of Persistent Bio-accumulating Toxins such as DDT and PCB's which are hydrophobic in nature and can cause adverse health affects.

A 2004 study by Richard Thompson from the University of Plymouth, UK, found a great amount of microdebris on the beaches and waters in Europe, the Americas, Australia, Africa, and Antarctica. Thompson and his associates found that plastic pellets from both domestic and industrial sources were being broken down into much smaller plastic pieces, some having a diameter smaller than human hair. If not ingested, this microdebris floats instead of being absorbed into the marine environment. Thompson predicts there may be 300,000 plastic items/km2 of sea surface and 100,000 plastic particles/km2 of seabed. International pellet watch collected samples of polythene pellets from 30 beaches from 17 countries which were then analysed for organic micro-pollutants. It was found that pellets found on beaches in America, Vietnam and southern Africa contained compounds from pesticides suggesting a high use of pesticides in the areas.

Macrodebris

Plastic debris is categorized as macrodebris when it is larger than 20 mm. These include items such as plastic grocery bags. Macrodebris are often found in ocean waters, and can have a serious impact on the native organisms. Fishing nets have been prime pollutants. Even after they have been abandoned, they continue to trap marine organisms and other plastic debris. Eventually, these abandoned nets become too difficult to remove from the water because they become too heavy, having grown in weight up to 6 tons.

Decomposition of plastics

Plastics themselves contribute to approximately 10% of discarded waste. Many kinds of plastics exist depending on their precursors and the method for their polymerization. Depending on their chemical composition, plastics and resins have varying properties related to contaminant absorption and adsorption. Polymer degradation takes much longer as a result of saline environments and the cooling effect of the sea. These factors contribute to the persistence of plastic debris in certain environments. Recent studies have shown that plastics in the ocean decompose faster than was once thought, due to exposure to sun, rain, and other environmental conditions, resulting in the release of toxic chemicals such as bisphenol A. However, due to the increased volume of plastics in the ocean, decomposition has slowed down. The Marine Conservancy has predicted the decomposition rates of several plastic products. It is estimated that a foam plastic cup will take 50 years, a plastic beverage holder will take 400 years, a disposable nappy will take 450 years, and fishing line will take 600 years to degrade.

Persistent organic pollutants

It was estimated that global production of plastics is approximately 250 mt/yr. Their abundance has been found to transport persistent organic pollutants, also known as POPs. These pollutants have been linked to an increased distribution of algae associated with red tides.

Effects on the environment

The distribution of plastic debris is highly variable as a result of certain factors such as wind and ocean currents, coastline geography, urban areas, and trade routes. Human population in certain areas also plays a large role in this. Plastics are more likely to be found in enclosed regions such as the Caribbean. It serves as a means of distribution of organisms to remote coasts that are not their native environments. This could potentially increase the variability and dispersal of organisms in specific areas that are less biologically diverse. Plastics can also be used as vectors for chemical contaminants such as persistent organic pollutants and heavy metals.

Plastic Pollution as one of the cause of Climate change

In 2019 a new report "Plastic and Climate" was published. According to the report plastic wiil contribute Greenhouse gases in the equivalent of 850 million tons of Carbon dioxide (CO2) to the atmosphere in 2019. In current trend, annual emissions will grow to 1.34 billion tons by 2030. By 2050 plastic could emit 56 billion tons of greenhouse gas emissions, as much as 14 percent of the earth’s remaining carbon budget.

Effects of plastic on land

Chlorinated plastic can release harmful chemicals into the surrounding soil, which can then seep into groundwater or other surrounding water sources and also the ecosystem of the world. This can cause serious harm to the species that drink the water. 

Landfill areas contain many different types of plastics. In these landfills, there are many microorganisms which speed up the biodegradation of plastics. The microorganisms include bacteria such as Pseudomonas, nylon-eating bacteria, and Flavobacteria. These bacteria break down nylon through the activity of the nylonase enzyme. Breakdown of biodegradable plastics releases methane, a very powerful greenhouse gas that contributes significantly to global warming.

Effects of plastic on oceans

In 2012, it was estimated that there was approximately 165 million tons of plastic pollution in the world's oceans. One type of plastic that is of concern in terms of ocean plastic pollution is nurdles. Nurdles are manufactured plastic pellets (a type of microplastic) used in the creation of plastic products and are often shipped via cargo ship. Many billions of nurdles are spilled into oceans each year, and it has been estimated that globally, around 10% of beach litter consists of nurdles. Plastics in oceans typically degrade within a year, but not entirely. In the process, toxic chemicals such as bisphenol A and polystyrene can leach into waters from some plastics. Polystyrene pieces and nurdles are the most common types of plastic pollution in oceans, and combined with plastic bags and food containers make up the majority of oceanic debris.

One study estimated that there are more than 5 trillion plastic pieces (defined into the four classes of small microplastics, large microplastics, meso- and macroplastics) afloat at sea.

The litter that is being delivered into the oceans is toxic to marine life, and humans. The toxins that are components of plastic include diethylhexyl phthalate, which is a toxic carcinogen, as well as lead, cadmium, and mercury. 

Plankton, fish, and ultimately the human race, through the food chain, ingest these highly toxic carcinogens and chemicals. Consuming the fish that contain these toxins can cause an increase in cancer, immune disorders, and birth defects.

The majority of the litter near and in the ocean is made up of plastics and is a persistent pervasive source of marine pollution. According to Dr. Marcus Eriksen of The 5 Gyres Institute, there are 5.25 trillion particles of plastic pollution that weigh as much as 270,000 tons (2016). This plastic is taken by the ocean currents and accumulates in large vortexes known as ocean gyres. The majority of the gyres become pollution dumps filled with plastic.

Sources of ocean-based plastic pollution

Almost 20% of plastic debris that pollutes ocean water, which translates to 5.6 million tons, comes from ocean-based sources. MARPOL, an international treaty, "imposes a complete ban on the at-sea disposal of plastics". Merchant ships expel cargo, sewage, used medical equipment, and other types of waste that contain plastic into the ocean. In the United States, the Marine Plastic Pollution Research and Control Act of 1987 prohibits discharge of plastics in the sea, including from naval vessels. Naval and research vessels eject waste and military equipment that are deemed unnecessary. Pleasure crafts release fishing gear and other types of waste, either accidentally or through negligent handling. The largest ocean-based source of plastic pollution is discarded fishing gear (including traps and nets), estimated to be up to 90% of plastic debris in some areas.

Continental plastic litter enters the ocean largely through storm-water runoff, flowing into watercourses or directly discharged into coastal waters. Plastic in the ocean has been shown to follow ocean currents which eventually form into what is known as Great Garbage Patches. Knowledge of the routes that plastic follows in ocean currents comes from accidental container drops from ship carriers. For example, in May 1990 The Hansa Carrier, sailing from Korea to the United States, broke apart due to a storm, ultimately resulting in thousands of dumped shoes; these eventually started showing up on the U.S western coast, and Hawaii.

Land-based sources of ocean plastic pollution

Estimates for the contribution of land-based plastic vary widely. While one study estimated that a little over 80% of plastic debris in ocean water comes from land-based sources, responsible for 0.8 million tonnes (790,000 long tons; 880,000 short tons) every year. In 2015, Jambeck et al. calculated that 275 million tonnes (271,000,000 long tons; 303,000,000 short tons) of plastic waste was generated in 192 coastal countries in 2010, with 4.8 to 12.7 million tonnes (12,500,000 long tons; 14,000,000 short tons) entering the ocean - a percentage of only up to 5%.

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.

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."

A source that has caused concern is landfills. Most waste in the form of plastic in landfills are single-use items such as packaging. Discarding plastics this way leads to accumulation. Although disposing of plastic waste in landfills has less of a gas emission risk than disposal through incineration, the former has space limitations. Another concern is that the liners acting as protective layers between the landfill and environment can break, thus leaking toxins and contaminating the nearby soil and water. Landfills located near oceans often contribute to ocean debris because content is easily swept up and transported to the sea by wind or small waterways like rivers and streams. Marine debris can also result from sewage water that has not been efficiently treated, which is eventually transported to the ocean through rivers. Plastic items that have been improperly discarded can also be carried to oceans through storm waters.

Plastic pollution in the Pacific Ocean

North Pacific Subtropical Convergence Zone

In the Pacific Gyre, specifically 20°N-40°N latitude, large bodies with floating marine debris can be found. Models of wind patterns and ocean currents indicate that the plastic waste in the northern Pacific is particularly dense where the Subtropical Convergence Zone (STCZ), 23°N-37°N latitude, meets a southwest-northeast line, found north of the Hawaiian archipelago.

In the Pacific, there are two mass buildups: the western garbage patch and the eastern garbage patch, the former off the coast of Japan and the latter between Hawaii and California. The two garbage patches are both part of the great Pacific garbage patch, and are connected through a section of plastic debris off the northern coast of the Hawaiian islands. It is approximated that these garbage patches contain 100 million tons of debris. The waste is not compact, and although most of it is near the surface of the pacific, it can be found up to more than 100 feet deep in the water.

Research published in April 2017 reported "the highest density of plastic rubbish anywhere in the world" on remote and uninhabited Henderson Island in South Pacific as a result of the South Pacific Gyre. The beaches contain an estimated 37.7 million items of debris together weighing 17.6 tonnes. In a study transect on North Beach, each day 17 to 268 new items washed up on a 10-metre section. The study noted that purple hermit crabs (Coenobita spinosus) make their homes in plastic containers washed up on beaches.

Plastic pollution in tap water

A 2017 study found that 83% of tap water samples taken around the world contained plastic pollutants. This was the first study to focus on global drinking water pollution with plastics, and showed that with a contamination rate of 94%, tap water in the United States was the most polluted, followed by Lebanon and India. European countries such as the United Kingdom, Germany and France had the lowest contamination rate, though still as high as 72%. This means that people may be ingesting between 3,000 and 4,000 microparticles of plastic from tap water per year. The analysis found particles of more than 2.5 microns in size, which is 2500 times bigger than a nanometer. It is currently unclear if this contamination is affecting human health, but if the water is also found to contain nano-particle pollutants, there could be adverse impacts on human well-being, according to scientists associated with the study.

However, plastic tap water pollution remains under-studied, as are the links of how pollution transfers between humans, air, water, and soil.

Effects on animals

Plastic pollution has the potential to poison animals, which can then adversely affect human food supplies. Plastic pollution has been described as being highly detrimental to large marine mammals, described in the book Introduction to Marine Biology as posing the "single greatest threat" to them. Some marine species, such as sea turtles, have been found to contain large proportions of plastics in their stomach. When this occurs, the animal typically starves, because the plastic blocks the animal's digestive tract. Sometimes Marine mammals are entangled in plastic products such as nets, which can harm or kill them.

Entanglement

Sea turtle entangled in a ghost net
 
Entanglement in plastic debris has been responsible for the deaths of many marine organisms, such as fish, seals, turtles, and birds. These animals get caught in the debris and end up suffocating or drowning. Because they are unable to untangle themselves, they also die from starvation or from their inability to escape predators. Being entangled also often results in severe lacerations and ulcers. In a 2006 report known as Plastic Debris in the World's Oceans, it was estimated that at least 267 different animal species have suffered from entanglement and ingestion of plastic debris. It has been estimated that over 400,000 marine mammals perish annually due to plastic pollution in oceans. Marine organisms get caught in discarded fishing equipment, such as ghost nets. Ropes and nets used to fish are often made of synthetic materials such as nylon, making fishing equipment more durable and buoyant. These organisms can also get caught in circular plastic packaging materials, and if the animal continues to grow in size, the plastic can cut into their flesh. Equipment such as nets can also drag along the seabed, causing damage to coral reefs.

Ingestion

Marine animals

An exhibit at the Mote Marine Laboratory that displays plastic bags in the ocean that look similar to jellyfish.
 
Sea turtles are affected by plastic pollution. Some species are consumers of jelly fish, but often mistake plastic bags for their natural prey. This plastic debris can kill the sea turtle by obstructing the oesophagus. Baby sea turtles are particularly vulnerable according to a 2018 study by Australian scientists.

So too are whales. Large amounts of plastics have been found in the stomachs of beached whales. Plastic debris started appearing in the stomach of the sperm whale since the 1970s, and has been noted to be the cause of death of several whales. In June 2018, more than 80 plastic bags were found inside a dying pilot whale that washed up on the shores of Thailand. In March 2019, a dead Cuvier's beaked whale washed up in the Philippines with 88 lbs of plastic in its stomach. In April 2019, following the discovery of a dead sperm whale off of Sardinia with 48 pounds of plastic in its stomach, the World Wildlife Foundation warned that plastic pollution is one of the most dangerous threats to sea life, noting that five whales have been killed by plastic over a two year period.

Some of the tiniest bits of plastic are being consumed by small fish, in a part of the pelagic zone in the ocean called the Mesopelagic zone, which is 200 to 1000 metres below the ocean surface, and completely dark. Not much is known about these fish, other than that there are many of them. They hide in the darkness of the ocean, avoiding predators and then swimming to the ocean's surface at night to feed. Plastics found in the stomachs of these fish were collected during Malaspina's circumnavigation, a research project that studies the impact of global change on the oceans.

A study conducted by Scripps Institution of Oceanography showed that the average plastic content in the stomachs of 141 mesopelagic fish over 27 different species was 9.2%. Their estimate for the ingestion rate of plastic debris by these fish in the North Pacific was between 12000 and 24000 tons per year. The most popular mesopelagic fish is the lantern fish. It resides in the central ocean gyres, a large system of rotating ocean currents. Since lantern fish serve as a primary food source for the fish that consumers purchase, including tuna and swordfish, the plastics they ingest become part of the food chain. The lantern fish is one of the main bait fish in the ocean, and it eats large amounts of plastic fragments, which in turn will not make them nutritious enough for other fish to consume.

Deep sea animals have been found with plastics in their stomachs.

Birds

Plastic pollution does not only affect animals that live solely in oceans. Seabirds are also greatly affected. In 2004, it was estimated that gulls in the North Sea had an average of thirty pieces of plastic in their stomachs. Seabirds often mistake trash floating on the ocean's surface as prey. Their food sources often has already ingested plastic debris, thus transferring the plastic from prey to predator. Ingested trash can obstruct and physically damage a bird's digestive system, reducing its digestive ability and can lead to malnutrition, starvation, and death. Toxic chemicals called polychlorinated biphenyls (PCBs) also become concentrated on the surface of plastics at sea and are released after seabirds eat them. These chemicals can accumulate in body tissues and have serious lethal effects on a bird's reproductive ability, immune system, and hormone balance. Floating plastic debris can produce ulcers, infections and lead to death. Marine plastic pollution can even reach birds that have never been at the sea. Parents may accidentally feed their nestlings plastic, mistaking it for food. Seabird chicks are the most vulnerable to plastic ingestion since they can't vomit up their food like the adult seabirds.

After the initial observation that many of the beaches in New Zealand had high concentrations of plastic pellets, further studies found that different species of prion ingest the plastic debris. Hungry prions mistook these pellets for food, and these particles were found intact within the birds' gizzards and proventriculi. Pecking marks similar to those made by northern fulmars in cuttlebones have been found in plastic debris, such as styrofoam, on the beaches on the Dutch coast, showing that this species of bird also mistake plastic debris for food.

An estimate of 1.5 million Laysan albatrosses, which inhabit Midway Atoll, all have plastics in their digestive system. Midway Atoll is halfway between Asia and North America, and north of the Hawaiian archipelago. In this remote location, the plastic blockage has proven deadly to these birds. These seabirds choose red, pink, brown, and blue plastic pieces because of similarities to their natural food sources. As a result of plastic ingestion, the digestive tract can be blocked resulting in starvation. The windpipe can also be blocked, which results in suffocation. The debris can also accumulate in the animal's gut, and give them a false sense of fullness which would also result in starvation. On the shore, thousands of birds corpses can be seen with plastic remaining where the stomach once was. The durability of the plastics is visible among the remains. In some instances, the plastic piles are still present while the bird's corpse has decayed.

Similar to humans, animals exposed to plasticizers can experience developmental defects. Specifically, sheep have been found to have lower birth weights when prenatally exposed to bisphenol A. Exposure to BPA can shorten the distance between the eyes of a tadpole. It can also stall development in frogs and can result in a decrease in body length. In different species of fish, exposure can stall egg hatching and result in a decrease in body weight, tail length, and body length.

Effects on humans

Due to the use of chemical additives during plastic production, plastics have potentially harmful effects that could prove to be carcinogenic or promote endocrine disruption. Some of the additives are used as phthalate plasticizers and brominated flame retardants. Through biomonitoring, chemicals in plastics, such as BPA and phthalates, have been identified in the human population. Humans can be exposed to these chemicals through the nose, mouth, or skin. Although the level of exposure varies depending on age and geography, most humans experience simultaneous exposure to many of these chemicals. Average levels of daily exposure are below the levels deemed to be unsafe, but more research needs to be done on the effects of low dose exposure on humans. A lot is unknown on how severely humans are physically affected by these chemicals. Some of the chemicals used in plastic production can cause dermatitis upon contact with human skin. In many plastics, these toxic chemicals are only used in trace amounts, but significant testing is often required to ensure that the toxic elements are contained within the plastic by inert material or polymer.

It can also affect humans in which it may create an eyesore that interferes with enjoyment of the natural environment.

Clinical significance

Due to the pervasiveness of plastic products, most of the human population is constantly exposed to the chemical components of plastics. 95% of adults in the United States have had detectable levels of BPA in their urine. Exposure to chemicals such as BPA have been correlated with disruptions in fertility, reproduction, sexual maturation, and other health effects. Specific phthalates have also resulted in similar biological effects.

Thyroid hormone axis

Bisphenol A affects gene expression related to the thyroid hormone axis, which affects biological functions such as metabolism and development. BPA can decrease thyroid hormone receptor (TR) activity by increasing TR transcriptional corepressor activity. This then decreases the level of thyroid hormone binding proteins that bind to triiodothyronine. By affecting the thyroid hormone axis, BPA expoure can lead to hypothyroidism.

Sex hormones

BPA can disrupt normal, physiological levels of sex hormones. It does this by binding to globulins that normally bind to sex hormones such as androgens and estrogens, leading to the disruption of the balance between the two. BPA can also affect the metabolism or the catabolism of sex hormones. It often acts as an antiandrogen or as an estrogen, which can cause disruptions in gonadal development and sperm production.

Reduction efforts

Household items made of various types of plastic.
 
Efforts to reduce the use of plastics and to promote plastic recycling have occurred. Some supermarkets charge their customers for plastic bags, and in some places more efficient reusable or biodegradable materials are being used in place of plastics. Some communities and businesses have put a ban on some commonly used plastic items, such as bottled water and plastic bags. In January 2019 a "Global Alliance to End Plastic Waste" has been created. The alliance wants to clean the environment from existing waste and increase recycling, but it does not mention reduction in plastic production as one of its targets.

Biodegradable and degradable plastics

The use of biodegradable plastics has many advantages and disadvantages. Biodegradables are biopolymers that degrade in industrial composters. Biodegradables do not degrade as efficiently in domestic composters, and during this slower process, methane gas may be emitted.

There are also other types of degradable materials that are not considered to be biopolymers, because they are oil-based, similar to other conventional plastics. These plastics are made to be more degradable through the use of different additives, which help them degrade when exposed to UV rays or other physical stressors. Yet biodegradation-promoting additives for polymers have been shown not to significantly increase biodegradation.

Although biodegradable and degradable plastics have helped reduce plastic pollution, there are some drawbacks. One issue concerning both types of plastics is that they do not break down very efficiently in natural environments. There, degradable plastics that are oil-based may break down into smaller fractions, at which point they do not degrade further.

Incineration

Up to 60% of used plastic medical equipment is incinerated rather than deposited in a landfill as a precautionary measure to lessen the transmission of disease. This has allowed for a large decrease in the amount of plastic waste that stems from medical equipment. If plastic waste is not incinerated and disposed of properly, a harmful amount of toxins can be released and dispersed as a gas through air or as ash through air and waterways. Many studies have been done concerning the gaseous emissions that result from the incineration process.

Policy

Agencies such as the US Environmental Protection Agency and US Food and Drug Administration often do not assess the safety of new chemicals until after a negative side effect is shown. Once they suspect a chemical may be toxic, it is studied to determine the human reference dose, which is determined to be the lowest observable adverse effect level. During these studies, a high dose is tested to see if it causes any adverse health effects, and if it does not, lower doses are considered to be safe as well. This does not take into account the fact that with some chemicals found in plastics, such as BPA; lower doses can have a discernible effect. Even with this often complex evaluation process, policies have been put into place in order to help alleviate plastic pollution and its effects. Government regulations have been implemented that ban some chemicals from being used in specific plastic products. 

In Canada, the United States, and the European Union, BPA has been banned from being incorporated in the production of baby bottles and children's cups, due to health concerns and the higher vulnerability of younger children to the effects of BPA. Taxes have been established in order to discourage specific ways of managing plastic waste. The landfill tax, for example, creates an incentive to choose to recycle plastics rather than contain them in landfills, by making the latter more expensive. There has also been a standardization of the types of plastics that can be considered compostable. The European Norm EN 13432, which was set by the European Committee for Standardization (CEN), lists the standards that plastics must meet, in terms of compostability and biodegradability, in order to officially be labeled as compostable.

Institutional arrangements in Canada

The Canadian federal government formed a current institution that protects marine areas; this includes the mitigation of plastic pollution. In 1997, Canada adopted legislation for oceans management and passed the Oceans Act. Federal governance, Regional Governance, and Aboriginal Peoples are the actors involved in the process of decision-making and implementation of the decision. The Regional Governance bodies are federal, provincial, and territorial government agencies that hold responsibilities of the marine environment. Aboriginal Peoples in Canada have treaty and non-treaty rights related to ocean activities. According to the Canadian government, they respect these rights and work with Aboriginal groups in oceans management activities.

With the Oceans Act made legal, Canada made a commitment to conserve and protect the oceans. The Ocean Acts' underlying principle is sustainable development, precautionary and integrated management approach to ensure that there is a comprehensive understanding in protecting marine areas. In the integrated management approach, the Oceans Act designates federal responsibility to the Minister of Fisheries and Oceans Canada for any new and emerging ocean-related activities. The Act encourages collaboration and coordination within the government that unifies interested parties. Moreover, the Oceans Act engages any Canadians who are interested in being informed of the decision-making regarding ocean environment.

In 2005, federal organizations developed the Federal Marine Protected Areas Strategy. This strategy is a collaborative approach implemented by Fisheries and Oceans Canada, Parks Canada, and Environment Canada to plan and manage federal marine protected areas. The federal marine protected areas work with Aboriginal groups, industries, academia, environmental groups, and NGOs to strengthen marine protected areas. The federal marine protected areas network consists of three core programs: Marine Protected Areas, Marine Wildlife Areas, and National Marine Conservation Areas. The MPA is a program to be noted because it is significant in protecting ecosystems from the effects of industrial activities. The MPA guiding principles are Integrated Management, ecosystem-based management approach, Adaptive Management Approach, Precautionary Principle, and Flexible Management Approach. All five guiding principles are used collectively and simultaneously to collaborate and respect legislative mandates of individual departments, to use scientific knowledge and traditional ecological knowledge (TEK) to manage human activities, to monitor and report on programs to meet conservation objectives of MPAs, to use best available information in the absence of scientific certainty, and to maintain a balance between conservation needs and sustainable development objectives.

Collection

The two common forms of waste collection include curbside collection and the use of drop-off recycling centers. About 87 percent of the population in the United States (273 million people) have access to curbside and drop-off recycling centers. In curbside collection, which is available to about 63 percent of the United States population (193 million people), people place designated plastics in a special bin to be picked up by a public or private hauling company. Most curbside programs collect more than one type of plastic resin; usually both PETE and HDPE. At drop-off recycling centers, which are available to 68 percent of the United States population (213 million people), people take their recyclables to a centrally located facility. Once collected, the plastics are delivered to a materials recovery facility (MRF) or handler for sorting into single-resin streams to increase product value. The sorted plastics are then baled to reduce shipping costs to reclaimers.

There are varying rates of recycling per type of plastic, and in 2011, the overall plastic recycling rate was approximately 8% in the United States. Approximately 2.7 million tons of plastics were recycled in the U.S. in 2011. Some plastics are recycled more than others; in 2011 "29 percent of HDPE bottles and 29 percent of PET bottles and jars were recycled."

In May 2019, a new model to collect packaging from consumers and reuse it will begin. It is called "Loop". Consumers will drop the package in special shipping totes and then a pick up will take it. "Partners include Procter & Gamble, Nestlé, PepsiCo, Unilever, Mars Petcare, The Clorox Company, The Body Shop, Coca-Cola, Mondelēz, Danone and other firms.

Non-usage and reduction in usage

The Ministry of Drinking Water and Sanitation, Government of India, has requested various governmental departments to avoid the use of plastic bottles to provide drinking water during governmental meetings, etc., and to instead make arrangements for providing drinking water that do not generate plastic waste. The state of Sikkim has restricted the usage of plastic water bottles (in government functions and meetings) and styrofoam products. The state of Bihar has banned the usage of plastic water bottles in governmental meetings.

The 2015 National Games of India, organised in Thiruvananthapuram, was associated with green protocols. This was initiated by Suchitwa Mission that aimed for "zero-waste" venues. To make the event "disposable-free", there was ban on the usage of disposable water bottles. The event witnessed the usage of reusable tableware and stainless steel tumblers. Athletes were provided with refillable steel flasks. It is estimated that these green practices stopped the generation of 120 metric tonnes of disposable waste.

The state of Maharashtra, India effected the Maharashtra Plastic and Thermocol Products ban 23 June 2018, subjecting plastic users to fines and potential imprisonment for repeat offenders.

In July 2018, Albania became the first country in Europe to ban lightweight plastic bags. Albania’s environment minister Blendi Klosi said that businesses importing, producing or trading plastic bags less than 35 microns in thickness risk facing fines between 1 million to 1.5 million lek (€7,900 to €11,800).

In January 2019, Nestlé announced that it will phase-out the use of plastic straws starting in February 2019 and will end the use of plastic packaging that is not recyclable or resusable by 2025.

In January 2019, the Iceland supermarket chain, which specializes in frozen foods, pledged to "eliminate or drastically reduce all plastic packaging for its store-brand products by 2023."

In Bali, a pair of two sisters, Melati and Isabel Wijsen, have gone through efforts to ban plastic bags in 2019. Their organization Bye Bye Plastic Bags has spread to 28 locations around the world. 

In 2019 The New York (state) banned single use plastic bags and introduced a 5 cent fee for using single use paper bags. The ban will enter into force in 2020. This will not only reduce plastic bag usage in New York state (23,000,000,000 every year until now), but also eliminate 12 million barrels of oil used to make plastic bags used by the state each year.

Action for creating awareness

On 11 April 2013 in order to create awareness, artist Maria Cristina Finucci founded The Garbage Patch State at UNESCO –Paris in front of Director General Irina Bokova. First of a series of events under the patronage of UNESCO and of Italian Ministry of the Environment. International organisations have also been raising awareness of plastic pollution. 

Every year, June 5 is observed as World Environment Day to raise awareness and increase government action on the pressing issue. In 2018, India was host to the 43rd World Environment Day and the theme was ‘Beat Plastic Pollution' with focus on single-use or disposable plastic. The Ministry of Environment, Forest and Climate Change of India invited people to take care of their social responsibility and urged them to take up green good deeds in everyday life. Several states presented plans to ban plastic or drastically reduce the use.

Algaculture

From Wikipedia, the free encyclopedia

Algaculture is a form of aquaculture involving the farming of species of algae

The majority of algae that are intentionally cultivated fall into the category of microalgae (also referred to as phytoplankton, microphytes, or planktonic algae). Macroalgae, commonly known as seaweed, also have many commercial and industrial uses, but due to their size and the specific requirements of the environment in which they need to grow, they do not lend themselves as readily to cultivation (this may change, however, with the advent of newer seaweed cultivators, which are basically algae scrubbers using upflowing air bubbles in small containers).

Commercial and industrial algae cultivation has numerous uses, including production of food ingredients such as omega-3 fatty acids or natural food colorants and dyes, food, fertilizer, bioplastics, chemical feedstock (raw material), pharmaceuticals, and algal fuel, and can also be used as a means of pollution control.

Global production of farmed aquatic plants, overwhelmingly dominated by seaweeds, grew in output volume from 13.5 million tonnes in 1995 to just over 30 million tonnes in 2016.

Growing, harvesting, and processing algae

Monoculture

Most growers prefer monocultural production and go to considerable lengths to maintain the purity of their cultures. However, the microbiological contaminants are still under investigation.

With mixed cultures, one species comes to dominate over time and if a non-dominant species is believed to have particular value, it is necessary to obtain pure cultures in order to cultivate this species. Individual species cultures are also much needed for research purposes.

A common method of obtaining pure cultures is serial dilution. Cultivators dilute either a wild sample or a lab sample containing the desired algae with filtered water and introduce small aliquots (measures of this solution) into a large number of small growing containers. Dilution follows a microscopic examination of the source culture that predicts that a few of the growing containers contain a single cell of the desired species. Following a suitable period on a light table, cultivators again use the microscope to identify containers to start larger cultures.

Another approach is to use a special medium which excludes other organisms, including invasive algae. For example, Dunaliella is a commonly grown genus of microalgae which flourishes in extremely salty water that few other organisms can tolerate.

Alternatively, mixed algae cultures can work well for larval mollusks. First, the cultivator filters the sea water to remove algae which are too large for the larvae to eat. Next, the cultivator adds nutrients and possibly aerates the result. After one or two days in a greenhouse or outdoors, the resulting thin soup of mixed algae is ready for the larvae. An advantage of this method is low maintenance.

Growing algae

Microalgae is used to culture brine shrimp, which produce dormant eggs (pictured). The eggs can then be hatched on demand and fed to cultured fish larvae and crustaceans.
 
Water, carbon dioxide, minerals and light are all important factors in cultivation, and different algae have different requirements. The basic reaction for algae growth in water is carbon dioxide + light energy + water = glucose + oxygen + water. This is called autotrophic growth. It is also possible to grow certain types of algae without light, these types of algae consume sugars (such as glucose). This is known as heterotrophic growth.

Temperature

The water must be in a temperature range that will support the specific algal species being grown mostly between 15˚C and 35˚C.

Light and mixing

In a typical algal-cultivation system, such as an open pond, light only penetrates the top 3 to 4 inches (76–102 mm) of the water, though this depends on the algae density. As the algae grow and multiply, the culture becomes so dense that it blocks light from reaching deeper into the water. Direct sunlight is too strong for most algae, which can use only about ​110 the amount of light they receive from direct sunlight; however, exposing an algae culture to direct sunlight (rather than shading it) is often the best course for strong growth, as the algae underneath the surface is able to utilize more of the less intense light created from the shade of the algae above. 

To use deeper ponds, growers agitate the water, circulating the algae so that it does not remain on the surface. Paddle wheels can stir the water and compressed air coming from the bottom lifts algae from the lower regions. Agitation also helps prevent over-exposure to the sun. 

Another means of supplying light is to place the light in the system. Glow plates made from sheets of plastic or glass and placed within the tank offer precise control over light intensity, and distribute it more evenly. They are seldom used, however, due to high cost.

Odor and oxygen

The odor associated with bogs, swamps, indeed any stagnant waters, can be due to oxygen depletion caused by the decay of deceased algal blooms. Under anoxic conditions, the bacteria inhabiting algae cultures break down the organic material and produce hydrogen sulfide and ammonia which causes the odor. This hypoxia often results in the death of aquatic animals. In a system where algae is intentionally cultivated, maintained, and harvested, neither eutrophication nor hypoxia are likely to occur. 

Some living algae and bacteria, also produce odorous chemicals, particularly certain (cyanobacteria) (previously classed as blue-green algae) such as Anabaena. The most well-known of these odor-causing chemicals are MIB (2-methylisoborneol) and geosmin. They give a musty or earthy odor that can be quite strong. Eventual death of the cyanobacteria releases additional gas that is trapped in the cells. These chemicals are detectable at very low levels, in the parts per billion range, and are responsible for many "taste and odor" issues in drinking water treatment and distribution. Cyanobacteria can also produce chemical toxins that have been a problem in drinking water.

Nutrients

Nutrients such as nitrogen (N), phosphorus (P), and potassium (K) serve as fertilizer for algae, and are generally necessary for growth. Silica and iron, as well as several trace elements, may also be considered important marine nutrients as the lack of one can limit the growth of, or productivity in, a given area. Carbon dioxide is also essential; usually an input of CO2 is required for fast-paced algal growth. These elements must be dissolved into the water, in bio-available forms, for algae to grow.

Pond and bioreactor cultivation methods

Algae can be cultured in open ponds (such as raceway-type ponds and lakes) and photobioreactors. Raceway ponds may be less expensive.
Open ponds
Raceway pond used to cultivate microalgae. The water is kept in constant motion with a powered paddle wheel.
 
Raceway-type ponds and lakes are open to the elements. Open ponds are highly vulnerable to contamination by other microorganisms, such as other algal species or bacteria. Thus cultivators usually choose closed systems for monocultures. Open systems also do not offer control over temperature and lighting. The growing season is largely dependent on location and, aside from tropical areas, is limited to the warmer months. 

Open pond systems are cheaper to construct, at the minimum requiring only a trench or pond. Large ponds have the largest production capacities relative to other systems of comparable cost. Also, open pond cultivation can exploit unusual conditions that suit only specific algae. For instance, Dunaliella salina grow in extremely salty water; these unusual media exclude other types of organisms, allowing the growth of pure cultures in open ponds. Open culture can also work if there is a system of harvesting only the desired algae, or if the ponds are frequently re-inoculated before invasive organisms can multiply significantly. The latter approach is frequently employed by Chlorella farmers, as the growth conditions for Chlorella do not exclude competing algae. 

The former approach can be employed in the case of some chain diatoms since they can be filtered from a stream of water flowing through an outflow pipe. A "pillow case" of a fine mesh cloth is tied over the outflow pipe allowing other algae to escape. The chain diatoms are held in the bag and feed shrimp larvae (in Eastern hatcheries) and inoculate new tanks or ponds. 

Enclosing a pond with a transparent or translucent barrier effectively turns it into a greenhouse. This solves many of the problems associated with an open system. It allows more species to be grown, it allows the species that are being grown to stay dominant, and it extends the growing season – if heated, the pond can produce year round. Open race way ponds were used for removal of lead using live Spirulina (Arthospira) sp.
Photobioreactors
Algae can also be grown in a photobioreactor (PBR). A PBR is a bioreactor which incorporates a light source. Virtually any translucent container could be called a PBR; however, the term is more commonly used to define a closed system, as opposed to an open tank or pond. 

Because PBR systems are closed, the cultivator must provide all nutrients, including CO
2

A PBR can operate in "batch mode", which involves restocking the reactor after each harvest, but it is also possible to grow and harvest continuously. Continuous operation requires precise control of all elements to prevent immediate collapse. The grower provides sterilized water, nutrients, air, and carbon dioxide at the correct rates. This allows the reactor to operate for long periods. An advantage is that algae that grows in the "log phase" is generally of higher nutrient content than old "senescent" algae. Algal culture is the culturing of algae in ponds or other resources. Maximum productivity occurs when the "exchange rate" (time to exchange one volume of liquid) is equal to the "doubling time" (in mass or volume) of the algae. 

Different types of PBRs include:

Harvesting

A person stands in shallow water, gathering seaweed that has grown on a rope.
A seaweed farmer in Nusa Lembongan gathers edible seaweed that has grown on a rope.
 
Algae can be harvested using microscreens, by centrifugation, by flocculation and by froth flotation.
Interrupting the carbon dioxide supply can cause algae to flocculate on its own, which is called "autoflocculation". 

"Chitosan", a commercial flocculant, more commonly used for water purification, is far more expensive. The powdered shells of crustaceans are processed to acquire chitin, a polysaccharide found in the shells, from which chitosan is derived via de-acetylation. Water that is more brackish, or saline requires larger amounts of flocculant. Flocculation is often too expensive for large operations.
Alum and ferric chloride are other chemical flocculants. 

In froth flotation, the cultivator aerates the water into a froth, and then skims the algae from the top.
Ultrasound and other harvesting methods are currently under development.

Oil extraction

Algae oils have a variety of commercial and industrial uses, and are extracted through a variety of methods. Estimates of the cost to extract oil from microalgae vary, but are likely to be around three times higher than that of extracting palm oil.

Physical extraction

In the first step of extraction, the oil must be separated from the rest of the algae. The simplest method is mechanical crushing. When algae is dried it retains its oil content, which then can be "pressed" out with an oil press. Different strains of algae warrant different methods of oil pressing, including the use of screw, expeller and piston. Many commercial manufacturers of vegetable oil use a combination of mechanical pressing and chemical solvents in extracting oil. This use is often also adopted for algal oil extraction.

Osmotic shock is a sudden reduction in osmotic pressure, this can cause cells in a solution to rupture. Osmotic shock is sometimes used to release cellular components, such as oil.

Ultrasonic extraction, a branch of sonochemistry, can greatly accelerate extraction processes. Using an ultrasonic reactor, ultrasonic waves are used to create cavitation bubbles in a solvent material. When these bubbles collapse near the cell walls, the resulting shock waves and liquid jets cause those cells walls to break and release their contents into a solvent. Ultrasonication can enhance basic enzymatic extraction. The combination "sonoenzymatic treatment" accelerates extraction and increases yields.

Chemical extraction

Chemical solvents are often used in the extraction of the oils. The downside to using solvents for oil extraction are the dangers involved in working with the chemicals. Care must be taken to avoid exposure to vapors and skin contact, either of which can cause serious health damage. Chemical solvents also present an explosion hazard.

A common choice of chemical solvent is hexane, which is widely used in the food industry and is relatively inexpensive. Benzene and ether can also separate oil. Benzene is classified as a carcinogen.
Another method of chemical solvent extraction is Soxhlet extraction. In this method, oils from the algae are extracted through repeated washing, or percolation, with an organic solvent such as hexane or petroleum ether, under reflux in a special glassware. The value of this technique is that the solvent is reused for each cycle.

Enzymatic extraction uses enzymes to degrade the cell walls with water acting as the solvent. This makes fractionation of the oil much easier. The costs of this extraction process are estimated to be much greater than hexane extraction. The enzymatic extraction can be supported by ultrasonication. The combination "sonoenzymatic treatment" causes faster extraction and higher oil yields.

Supercritical CO2 can also be used as a solvent. In this method, CO2 is liquefied under pressure and heated to the point that it becomes supercritical (having properties of both a liquid and a gas), allowing it to act as a solvent.

Other methods are still being developed, including ones to extract specific types of oils, such as those with a high production of long-chain highly unsaturated fatty acids.

Algal culture collections

Specific algal strains can be acquired from algal culture collections, with over 500 culture collections registered with the World Federation for Culture Collections.

Uses of algae

Dulse is one of many edible algae.

Food

Several species of algae are raised for food.
  • Purple laver (Porphyra) is perhaps the most widely domesticated marine algae. In Asia it is used in nori (Japan) and gim (Korea). In Wales, it is used in laverbread, a traditional food, and in Ireland it is collected and made into a jelly by stewing or boiling. Preparation also can involve frying or heating the fronds with a little water and beating with a fork to produce a pinkish jelly. Harvesting also occurs along the west coast of North America, and in Hawaii and New Zealand.
  • Dulse (Palmaria palmata) is a red species sold in Ireland and Atlantic Canada. It is eaten raw, fresh, dried, or cooked like spinach.
  • Spirulina (Arthrospira platensis) is a blue-green microalgae with a long history as a food source in East Africa and pre-colonial Mexico. Spirulina is high in protein and other nutrients, finding use as a food supplement and for malnutrition. Spirulina thrives in open systems and commercial growers have found it well-suited to cultivation. One of the largest production sites is Lake Texcoco in central Mexico. The plants produce a variety of nutrients and high amounts of protein. Spirulina is often used commercially as a nutritional supplement. Best benefit of Spirulina is the high pH of the culture medium, which can vary in 6-13. The high pH will not allow other microbes to reproduce.
  • Chlorella, another popular microalgae, has similar nutrition to spirulina. Chlorella is very popular in Japan. It is also used as a nutritional supplement with possible effects on metabolic rate. Some allege that Chlorella can reduce mercury levels in humans (supposedly by chelation of the mercury to the cell wall of the organism).
  • Irish moss (Chondrus crispus), often confused with Mastocarpus stellatus, is the source of carrageenan, which is used as a stiffening agent in instant puddings, sauces, and dairy products such as ice cream. Irish moss is also used by beer brewers as a fining agent.
  • Sea lettuce (Ulva lactuca), is used in Scotland where it is added to soups and salads.
  • Dabberlocks or badderlocks (Alaria esculenta) is eaten either fresh or cooked in Greenland, Iceland, Scotland and Ireland.
  • Aphanizomenon flos-aquae is a cyanobacteria similar to spirulina, which is used as a nutritional supplement.
  • Extracts and oils from algae are also used as additives in various food products. The plants also produce Omega-3 and Omega-6 fatty acids, which are commonly found in fish oils, and which have been shown to have positive health benefits.
  • Sargassum species are an important group of seaweeds. These algae have many phlorotannins.
  • Cochayuyo (Durvillaea antarctica) is eaten in salads and ceviche in Peru and Chile.

Fertilizer and agar

For centuries seaweed has been used as fertilizer. It is also an excellent source of potassium for manufacture of potash and potassium nitrate. Also some of microalgae can be used like this. 

Both microalgae and macroalgae are used to make agar.

Pollution control

With concern over global warming, new methods for the thorough and efficient capture of CO2 are being sought out. The carbon dioxide that a carbon-fuel burning plant produces can feed into open or closed algae systems, fixing the CO2 and accelerating algae growth. Untreated sewage can supply additional nutrients, thus turning two pollutants into valuable commodities.

Algae cultivation is under study for uranium/plutonium sequestration and purifying fertilizer runoff.

Energy production

Business, academia and governments are exploring the possibility of using algae to make gasoline, bio-diesel, biogas and other fuels. Algae itself may be used as a biofuel, and additionally be used to create hydrogen.

Other uses

Chlorella, particularly a transgenic strain which carries an extra mercury reductase gene, has been studied as an agent for environmental remediation due to its ability to reduce Hg2+ to the less toxic elemental mercury.

Cultivated algae serve many other purposes, including cosmetics, animal feed, bioplastic production, dyes and colorant production, chemical feedstock production, and pharmaceutical ingredients.

Monday, May 20, 2019

Buddhism in Vietnam

From Wikipedia, the free encyclopedia

Minh Thanh Pagoda
Minh Thanh Pagoda, Ly, Tran Dynasty.
 
Buddhism in Vietnam (Đạo Phật or Phật Giáo in Vietnamese), as practised by the ethnic Vietnamese, is mainly of the Mahayana tradition. Buddhism may have first come to Vietnam as early as the 3rd or 2nd century BCE from the Indian subcontinent or from China in the 1st or 2nd century CE. Vietnamese Buddhism has had a syncretic relationship with certain elements of Taoism, Chinese spirituality and the Vietnamese folk religion.

History

Dynastic period

There are conflicting theories regarding whether Buddhism first reached Vietnam during the 3rd or 2nd century BCE via delegations from India, or during the 1st or 2nd century from China. In either case, by the end of the second century CE, Vietnam had developed into a major regional Mahayana Buddhist center centering on Luy Lâu in modern Bắc Ninh Province, northeast of the present day capital city of Hanoi. Luy Lâu was the capital of the Han region of Jiaozhi and was a popular place visited by many Indian Buddhist missionary monks en route to China. The monks followed the maritime trade route from the Indian sub-continent to China used by Indian traders. A number of Mahayana sutras and the āgamas were translated into Classical Chinese there, including the Sutra of Forty-two Chapters and the Anapanasati

Jiaozhi was the birthplace of Buddhist missionary Kang Senghui who was of Sogdian origin.

Over the next eighteen centuries, Vietnam and China shared many common features of cultural, philosophical and religious heritage. This was due to geographical proximity to one another and Vietnam being annexed twice by China. Vietnamese Buddhism is thus related to Chinese Buddhism in general, and to some extent reflects the formation of Chinese Buddhism after the Song dynasty. Theravada Buddhism, on the other hand, would become incorporated through the southern annexation of Khmer people and territories. 

During the Đinh dynasty (968–980), Buddhism was recognized by the state as an official faith (~971), reflecting the high esteem of Buddhist faith held by the Vietnamese monarchs. The Early Lê dynasty (980–1009) also afforded the same recognition to the Buddhist church. The growth of Buddhism during this time is attributed to the recruitment of erudite monks to the court as the newly independent state needed an ideological basis on which to build a country. Subsequently, this role was ceded to Confucianism.

Vietnamese Buddhism reached its zenith during the Lý dynasty (1009–1225) beginning with the founder Lý Thái Tổ, who was raised in a pagoda. All of the kings during the Lý dynasty professed and sanctioned Buddhism as the state religion. This endured with the Trần dynasty (1225–1400) but Buddhism had to share the stage with the emerging growth of Confucianism

By the 15th century, Buddhism fell out of favor with the court during the Later Lê dynasty, although still popular with the masses. Officials like Lê Quát attacked it as heretical and wasteful. It was not until the 19th century that Buddhism regained some stature under the Nguyễn dynasty who accorded royal support.

A Buddhist revival movement (Chấn hưng Phật giáo) emerged in the 1920s in an effort to reform and strengthen institutional Buddhism, which had lost grounds to the spread of Christianity and the growth of other faiths under French rule. The movement continued into the 1950s.

Republican period

Monument to Thích Quảng Đức, who burned himself to death in 1963 in protest against the persecution of Buddhists by South Vietnam's Ngô Đình Diệm administration

From 1954 to 1975, Vietnam was split into North and South Vietnam. In a country where surveys of the religious composition estimated the Buddhist majority to be approximately 50 to 70 percent, President Ngô Đình Diệm's policies generated claims of religious bias. As a member of the Catholic Vietnamese minority, he pursued pro-Catholic policies that antagonized many Buddhists.

In May 1963, in the central city of Huế, where Diệm's elder brother Ngô Đình Thục was the archbishop, Buddhists were prohibited from displaying Buddhist flags during Vesak celebrations yet few days earlier, Catholics were allowed to fly religious flags at a celebration in honour of the newly seated archbishop. This led to widespread protest against the government; troops were sent in and nine civilians were killed in the confrontations. This led to mass rallies against Diệm's government, termed as the Buddhist crisis. The conflicts culminated in Thích Quảng Đức's self-immolation. President Diệm's younger brother Ngô Đình Nhu favored strong-armed tactics and Army of the Republic of Vietnam Special Forces engaged in the Xá Lợi Pagoda raids, killing estimated hundreds. Dismayed by the public outrage, the US government withdrew support for the regime. President Diệm was deposed and killed in the 1963 coup.
 
Political strength of the Buddhists grew in the 1960s as the different schools and orders convene to form the Unified Buddhist Church of Vietnam. Leaders of the Church like Thích Trí Quang had considerable sway in national politics, at times challenging the government.

With the fall of Saigon in 1975, the whole nation came under Communist rule; many religious practices including Buddhism were discouraged. In the North the government had created the United Buddhist Sangha of Vietnam, co-opting the clergy to function under government auspices but in the South, the Unified Buddhist Sangha of Vietnam still held sway and openly challenged the communist government. The Sangha leadership was thus arrested and imprisoned; Sangha properties were seized and the Sangha itself was outlawed. In its place was the newly created Buddhist Sangha of Vietnam, designed as the final union of all Buddhist organizations, now under full state control.

Modern period

The treatment on Buddhists started to ease since Đổi mới at 1986. 

Since Đổi Mới (1986) many reforms have allowed Buddhism to be practiced relatively unhindered by the individuals. However no organized sangha is allowed to function independent of the state. It was not until 2007 that Pure Land Buddhism, the most widespread type of Buddhism practiced in Vietnam, was officially recognized as a religion by the government. Thích Quảng Độ the Patriarch of the Unified Buddhist Sangha, once imprisoned, remains under surveillance and restricted in his travels. 

Today, Buddhists are found throughout in Vietnam, from North to South. Buddhism is the single largest organized religion in Vietnam, with somewhere between 12.2% and 16.4% of the population identifying themselves as Buddhist. Some argued the number to be higher than general, as many declared itself as atheists, but still participate on Buddhist activities. 

In one side, though the Communist Party of Vietnam officially promotes atheism, it has usually leaned in favor to Buddhism, as Buddhism is associated with the long and deep history of Vietnam, and also, there have been rarely disputes between Buddhists and the Government; the Communist Government also sees Buddhism as a symbol of Vietnamese patriotism. Buddhist festivals are officially promoted by the Government and restrictions are few, in contrast to its Christian, Muslim and other religious counterparts.

Recently, the Communist regime in Vietnam allows major Buddhist figures to enter the country. Thích Nhất Hạnh, a major Buddhist figure revered both in Vietnam and worldwide, is among these. In order to distance itself from the fellow communist neighbor China, the Government of Vietnam allows publishing books and stories of 14th Dalai Lama, who has a personal friendship with Thích Nhất Hạnh and were commonly critical of Chinese regime after 2008 Tibetan unrest, which was seen as an attempt to antagonize Chinese Government and China as a whole as Beijing considers Dalai Lama as a terrorist.

Overseas

Buddhist Monastery of Tam Bao Son, Harrington, Quebec, Canada
 
After the fall of South Vietnam to communism in 1975 at the end of the Vietnam War, the first major Buddhist community appeared in North America. Since this time, the North American Vietnamese Buddhist community has grown to some 160 temples and centers. Proselytizing is not a priority. 

The most famous practitioner of synchronized Vietnamese Thiền in the West is Thích Nhất Hạnh who has authored dozens of books and founded the Plum Village Monastery in France together with his colleague, bhikṣuṇī and Zen Master Chân Không. According to Nguyen and Barber, Thích Nhất Hạnh's fame in the Western world as a proponent of engaged Buddhism and a new Thiền style has "no affinity with or any foundation in traditional Vietnamese Buddhist practices" and according to Alexander Soucy (2007) his style of Zen Buddhism is not reflective of actual Vietnamese Buddhism. Thích Nhất Hạnh often recounts about his early Thiền practices in Vietnam in his Dharma talks saying that he continued and developed this practice in the West which has a distinctive Vietnamese Thiền flavor.

Thích Nhất Hạnh's Buddhist teachings have started to return to a Vietnam where the Buddhist landscape is now being shaped by the combined Vietnamese and Westernized Buddhism that is focused more on the meditative practices.

Practice

Vietnamese art of the pure land of Kṣitigarbha.
 
Followers in Vietnam practice differing traditions without any problem or sense of contradiction. Few Vietnamese Buddhists would identify themselves as a particular kind of Buddhism, as a Christian might identify him or herself by a denomination, for example. Although Vietnamese Buddhism does not have a strong centralized structure, the practice is similar throughout the country at almost any temple. 

Gaining merit is the most common and essential practice in Vietnamese Buddhism with a belief that liberation takes place with the help of Buddhas and bodhisattvas. Buddhist monks commonly chant sutras, recite Buddhas’ names (particularly Amitābha), doing repentance and praying for rebirth in the Pure Land.

The Lotus Sutra and the Amitabha Sutra are the most commonly used sutras. Most sutras and texts are in Classical Chinese and are merely recited with Sino-Xenic pronunciations, making them incomprehensible to most practitioners. 

Three services are practiced regularly at dawn, noon, and dusk. They include sutra reading with niệm Phật and dhāraṇī recitation and kinh hành (walking meditation). Laypeople at times join the services at the temple and some devout Buddhist practice the services at home. Special services such as Sam Nguyen/Sam Hoi (confession/repentance) takes place on the full moon and new moon each month. Niệm Phật practice is one way of repenting and purifying bad karma.

Buddhist temples also serve a significant role in death rituals and funerals among overseas Vietnamese.

Branches

Mahāyāna traditions

Bái Đính Temple in Ninh Bình Province
 
Monks holding a service in Huế
 
The overall doctrinal position of Vietnamese Buddhism is the inclusive system of Tiantai, with the higher metaphysics informed by the Huayan school (Vietnamese: Hoa Nghiêm); however, the orientation of Vietnamese Buddhism is syncretic without making such distinctions. Therefore, modern practice of Vietnamese Buddhism can be very eclectic, including elements from Thiền (Chan Buddhism), Thiên Thai (Tiantai), Tịnh độ Pure Land Buddhism, and popular practices from Vajrayana. According to Charles Prebish, many English language sources contain misconceptions regarding the variety of doctrines and practices in traditional Vietnamese Buddhism:
We will not consider here the misconceptions presented in most English-language materials regarding the distinctness of these schools, and the strong inclination for "syncretism" found in Chinese and Vietnamese Buddhism. Much has been said about the incompatibility of different schools and their difficulty in successfully communicating with each other and combining their doctrines. None of these theories reflects realities in Vietnam (or China) past or present. The followers have no problem practicing the various teachings at the same time.
The methods of Pure Land Buddhism are perhaps the most widespread within Vietnam. It is common for practitioners to recite sutras, chants and dhāraṇīs looking to gain protection through bodhisattvas or dharmapalas. It is a devotional practice where those practicing put their faith in Amitābha (Vietnamese: A-di-đà). Followers believe they will gain rebirth in his pure land by chanting Amitabha's name. A pure land is a Buddha-realm where one can more easily attain enlightenment since suffering does not exist there. 

Many religious organizations have not been recognized by the government; however, in 2007, with 1.5 million followers, the Vietnamese Pure Land Buddhism Association (Tịnh Độ Cư Sĩ Phật Hội Việt Nam) received official recognition as an independent and legal religious organization.

Thiền is the Sino-Xenic pronunciation of Chan (Japanese Zen) and is derived ultimately from Sanskrit "dhyāna". The traditional account is that in 580, an Indian monk named Vinitaruci (Vietnamese: Tì-ni-đa-lưu-chi) traveled to Vietnam after completing his studies with Sengcan, the third patriarch of Chan Buddhism. This would be the first appearance of Thiền. The sect that Vinitaruci and his lone Vietnamese disciple founded would become known as the oldest branch of Thiền. After a period of obscurity, the Vinitaruci School became one of the most influential Buddhist groups in Vietnam by the 10th century, particularly under the patriarch Vạn-Hạnh (died 1018). Other early Vietnamese Zen schools included the Vô Ngôn Thông, which was associated with the teaching of Mazu Daoyi, and the Thảo Đường, which incorporated nianfo chanting techniques; both were founded by Chinese monks. 

A new Thiền school was founded by King Trần Nhân Tông (1258–1308); called the Trúc Lâm "Bamboo Grove" school, it evinced a deep influence from Confucian and Taoist philosophy. Nevertheless, Trúc Lâm's prestige waned over the following centuries as Confucianism became dominant in the royal court. In the 17th century, a group of Chinese monks led by Nguyên Thiều introduced the Ling school (Lâm Tế). A more native offshoot of Lâm Tế, the Liễu Quán school, was founded in the 18th century and has since been the predominant branch of Vietnamese Zen. 

This is the main altar of a Vietnamese Buddhist temple near Seattle. In the front is a statue of Shakyamuni Buddha, the historical founder, while in the back is the "trinity" of Amitabha Buddha. On one side of Amitabha is Avalokitesvara Bodhisattva while on the other is Mahasthamaprapta Bodhisattva.
 
Some scholars argue that the importance and prevalence of Thiền in Vietnam has been greatly overstated and that it has played more of an elite rhetorical role than a role of practice. The Thiền uyển tập anh (Chinese: 禪苑集英, "Collection of Outstanding Figures of the Zen Garden") has been the dominant text used to legitimize Thiền lineages and history within Vietnam. However, Cuong Tu Nguyen's Zen in Medieval Vietnam: A Study and Translation of the Thien Tap Anh (1997) gives a critical review of how the text has been used to create a history of Zen Buddhism that is "fraught with discontinuity". Modern Buddhist practices are not reflective of a Thiền past; in Vietnam, common practices are more focused on ritual and devotion than the Thiền focus on meditation. Nonetheless, Vietnam is seeing a steady growth in Zen today. Two figures who have been responsible for this increased interest in Thiền are Thích Nhất Hạnh, and Thích Thanh Từ, who lives in Da Lat.

Theravada

South East Asia circa 1010 CE, Đại Việt (Vietnamese) lands in yellow
 
The central and southern part of present-day Vietnam were originally inhabited by the Chams and the Khmer people, respectively, who followed both a syncretic Śaiva-Mahayana and Theravada Buddhism. Đại Việt annexed the land occupied by the Cham during conquests in the 15th century and by the 18th century had also annexed the southern portion of the Khmer Empire, resulting in the current borders of Vietnam. From that time onward, the dominant Đại Việt (Vietnamese) followed the Mahayana tradition while the Khmer continued to practice Theravada. 

In the 1920s and 1930s, there were a number of movements in Vietnam for the revival and modernization of Buddhist activities. Together with the re-organization of Mahayana establishments, there developed a growing interest in Theravadin meditation as well as the Pāli Canon. These were then available in French. Among the pioneers who brought Theravada Buddhism to the ethnic Đại Việt was a young veterinary doctor named Lê Văn Giảng. He was born in the South, received higher education in Hanoi, and after graduation, was sent to Phnom Penh, Cambodia, to work for the French government.

During that time he became especially interested in Theravada Buddhist practice. Subsequently, he decided to ordain and took the Dhamma name of Hộ-Tông (Vansarakkhita). In 1940, upon an invitation from a group of lay Buddhists led by Nguyễn Văn Hiểu, he went back to Vietnam in order to help establish the first Theravada temple for Vietnamese Buddhists at Gò Dưa, Thủ Đức (now a district of Hồ Chí Minh City). The temple was named Bửu Quang (Ratana Ramsyarama). The temple was destroyed by French troops in 1947, and was later rebuilt in 1951. At Bửu Quang temple, together with a group of Vietnamese bhikkhus who had received training in Cambodia such as Thiện Luật, Bửu Chơn, Kim Quang and Giới Nghiêm, Hộ Tông began teaching Buddhism in their native Vietnamese. He also translated many Buddhist materials from the Pali Canon, and Theravada became part of Vietnamese Buddhist activity in the country.

In 1949–1950, Hộ Tông together with Nguyễn Văn Hiểu and supporters built a new temple in Saigon (now Hồ Chí Minh City), named Kỳ Viên Tự (Jetavana Vihara). This temple became the centre of Theravada activities in Vietnam, which continued to attract increasing interest among the Vietnamese Buddhists. In 1957, the Vietnamese Theravada Buddhist Sangha Congregation (Giáo Hội Tăng Già Nguyên Thủy Việt Nam) was formally established and recognised by the government, and the Theravada Sangha elected Venerable Hộ Tông as its first President, or Sangharaja. 

From Saigon, the Theravada movement spread to other provinces, and soon, a number of Theravada temples for ethnic Viet Buddhists were established in many areas in the South and Central parts of Vietnam. There are 529 Theravada temples throughout the country, of which 19 were located in Hồ Chí Minh City and its vicinity. Besides Bửu Quang and Kỳ Viên temples, other well known temples are Bửu Long, Giác Quang, Tam Bảo (Đà Nẵng), Thiền Lâm and Huyền Không (Huế), and the large Thích Ca Phật Đài in Vũng Tàu.

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