ABSTRACT
The protection of oceans and ecosystems, along with the achievement of sustainable ocean economies, has become a global priority. This paper tries maps the current situation of pollution in the oceans across the world, focusing on both the causes and consequences of garbage patches in the oceans and the most affected areas. In the first part, some quantitative analysis on the amount of plastic has been carried out, with an overview of the countries and economic actors that pollute the most. Attention is then drawn to the clean-up technologies (blue tech) available nowadays and the operational projects in which they are used. These technologies act more or less upstream in the plastic pollution chain: from cleaning wastewater before it flows into the sea, to collecting plastic from rivers, to removing it from the great garbage patches that form in the oceans. In the conclusions, it is outlined how, to achieve sustainable development across social, environmental, and economic dimensions, ocean protection must be intrinsically linked to many other SDGs. All countries will need to benefit from it, especially the poorest and most vulnerable ones, which are the most exposed to the negative consequences of ocean pollution and have the fewest resources available to face them.
Authors: Alessandra Colasanti - Senior Researcher G.E.O. Environment; Erica Trotta - Junior Researcher G.E.O. Environment
1. Plastic pollution: an “ocean” of problems
Plastic is a petroleum-based synthetic organic polymer having qualities that make it appropriate for a wide range of uses including: packaging, construction, household and sports equipment, automobiles, electronics, and agriculture. Every year, over 300 million tons of plastic are produced, with half of that going into single-use products such as shopping bags, cups, and straws (IUCN, 2021).
Plastic waste, when discarded improperly, can harm the environment and biodiversity. Each year, at least 14 million tons of plastic end up in the ocean and so plastic debris is now the most abundant type of litter in the ocean, accounting for 80 percent of all marine debris discovered from surface waters to deep-sea sediments (IUCN, 2021). Plastic can be found on every continent's shorelines, with more plastic waste found near popular tourist destinations and densely populated areas.
Land-based sources of plastic debris in the ocean include urban and stormwater runoff, sewer overflows, littering, inadequate waste disposal and management, industrial activities, tyre abrasion, construction, and illegal dumping. Plastic pollution in the ocean is primarily caused by the fishing industry, nautical activities, and aquaculture.
Plastic degrades into small particles known as microplastics - particles smaller than 5 mm- or nanoplastics - particles smaller than 100 nm - resulting from sun UV radiation, wind, currents, and other natural forces. Because of their small size, they could be easily ingested by aquatic creatures (IUCN, 2021).
Many countries lack the infrastructure needed to avoid plastic pollution, such as sanitary landfills, incinerator facilities, recycling systems, circular economy infrastructure, as well as appropriate waste treatment and garbage disposal.
As a result, 'plastic leakage' occurs mostly in rivers and oceans. When waste management systems are insufficient to limit plastic trash, the legal and criminal worldwide trafficking of plastic garbage may harm ecosystems.
2. The heart of the problem
Plastic has now become an extremely common component in the water, and as a result, plastic pollution is a pervasive issue harming the marine ecosystem. It jeopardizes ocean health, marine species’ health, food quality, human health and security, and coastal tourism, not to mention that it even further contributes to climate change (IUCN, 2021).
a) Impacts on marine ecosystems: Plastic debris's most evident effects are the ingestion, suffocation, and entanglement of hundreds of marine species. Seabirds, whales, fish, and turtles mistake plastic garbage for prey, and most of them die of malnutrition as their stomachs fill with plastic. Lacerations, infections, impaired swimming capacity, and internal damage are also possible. Lastly, floating plastics also aid in the transfer of invasive marine species, endangering marine biodiversity and the food web.
b) Impacts on food and human health: Microplastics have been discovered in tap water, beer, and salt, as well as in all ocean samples taken across the world, including in the Arctic. Several chemicals used in the manufacture of plastic products are known to be carcinogenic and to disrupt the body's endocrine system, resulting in developmental, reproductive, neurological, and immunological issues in both humans and wildlife. Microplastics have recently been discovered in human placentas, but further research is needed to determine whether this is a widespread concern. Toxic contaminants develop on the surface of plastic as a result of continuous exposure to seawater; thus, the transmission of toxins between marine organisms and humans, via seafood, has been identified as a human health risk.
c) Impacts on tourism: plastic waste degrades the aesthetic value of tourist destinations, resulting in lower tourism revenue. It also produces significant economic costs for cleaning and maintaining the sites. Plastic waste on beaches can have a severe influence on a country's economy, biodiversity, and people's physical and psychological well-being.
d) Impacts on climate change: plastic manufacturing adds to global warming. Indeed, incineration of plastic trash sends carbon dioxide and methane (from landfills) into the atmosphere, increasing emissions.
The United Nations 2030 Agenda for Sustainable Development calls for action to 'conserve and sustainably use the oceans, seas, and marine resources' (Goal 14) and to 'prevent and significantly reduce marine pollution of all kinds, particularly from land-based activities, including marine debris and nutrient pollution,' by 2025 (Target 14.1) (UN, 2021).
3. A worldwide problem
The issue of plastic in the oceans affects the entire world.
Garbage patches are huge areas of the ocean where litter, fishing gear, and other debris - together known as marine debris - accumulate. They are generated by rotating ocean currents known as "gyres," which resemble slow-moving whirlpools. There are five gyres: the North Atlantic Gyre, the South Atlantic Gyre, the North Pacific Gyre, the South Pacific Gyre, and the Indian Ocean Gyre. They assist in driving the so-called oceanic conveyor belt, which circulates ocean waters across the world. While they cycle ocean waters, they also collect marine debris, which is pollution that we discharge in coastal areas. As a result, the gyres draw debris into one spot, usually the gyre's center, generating "patches" (Filho,2021).
The world's largest garbage patch is the Great Pacific garbage patch which is located in the North Pacific gyre. The patch's estimated extent is 1.6 million km2, nearly three times the size of France. The enormous pile is currently made up of an estimated 80,000 tons of garbage, although pollution in the area appears to be increasing at a quicker rate than in nearby places.
The South Pacific garbage patch located in the South Pacific gyres is estimated to cover around 2.6 million km2. The debris is concentrated in the gyre's core rather than its margins. Furthermore, due to increased fishing activity in the area, there was a huge amount of fishing lines and nets in the debris. The waste is mostly made of micro plastics since these materials have broken down into smaller fractions.
The Indian Ocean garbage patch is located within the Indian Ocean gyre. The patch's current size is believed to be between 2.1 and 5.0 million km2. The patch has been linked to the deaths of sea turtles, as proven by several of them washing up on shore with plastic in their stomachs and intestines.
The North Atlantic garbage patch is located at the North Atlantic gyre. It was detected for the first time in 1976. The actual size is unknown; however it is said to stretch hundreds of kilometers. Estimations show that approximately 200,000 pieces of debris are recovered per km2.
The South Atlantic Plastic gyre hosts the smallest of the five garbage patches. The size is approximately 0.7 million km2. According to recent research, bottles from Asia are the most common source of garbage in this area. Bottles stranded from Asia on the inhabited Tristan da Cunha archipelago are thought to be the main feeder of the rubbish patch. This is primarily due to ships dropping such bottles into the water.
When compared to the edges, which are less packed, the core regions of the garbage patches have a larger density and carry most of the weight. Attempts to quantify the patch mass tend to concentrate on the core sections. Defining the size of the waste patches is difficult precisely due to the trash's constant movement due to ocean currents and winds (Filho,2021).
A new ingredient has been added to the garbage since spring 2020: used face masks.
4. How much plastic is there in oceans and rivers?
The plastic problem lacks the scientific foundation required to accurately assess, map, and expose the severity of the problem and manage the solutions (too many reports and not enough data).
The best study available today, according to the World Economic Forum (WEF), indicates that there are 150 million tons of plastic in the oceans. If nothing changes in the industrial method, it is estimated that by 2025, there will be one ton of plastic for every three tons of fish. Additionally, by 2050, the weight of plastic is expected to surpass that of marine life. Current studies estimate that 1.15 to 2.41 million tons of plastic are entering the ocean each year from rivers. More than half of this plastic is less dense compared with water, meaning that it will not sink once it encounters the sea.
Stronger, more buoyant plastics are more resilient in the maritime environment, allowing them to travel long distances. They remain at the sea surface as they travel offshore, being carried by converging currents and eventually aggregating in the patch. Once in the gyre, these plastics are unlikely to depart until they break down into smaller microplastics due to the influence of the sun, waves, and marine life (Esri, 2019).
The Great Pacific Garbage Patch is the most studied Garbage Patch (GPGP) (Van Sebille et al., 2012).
As previously stated, the GPGP is predicted to cover 1.6 million square kilometers of land; to arrive at this result, the experts behind this study used the most comprehensive sampling procedure yet developed. A fleet of 30 boats, 652 surface nets, and two flights over the patch were used to collect aerial photographs of the wreckage. Sampling at multiple sites during the same timespan allowed for a more precise estimation of the size of the patch and the plastic drifting in it (The Ocean Clean Up, 2021).
A total of 1.8 trillion plastic bits were estimated to be floating in it — the equivalent of 250 pieces of trash per-capita on the planet. The team chose to use cautious estimates of the plastic count, similar to how they calculated the mass. While 1.8 trillion is a reasonable estimate for the total number of pieces, their projections indicate that it might range from 1.1 to 3.6 trillion. The characteristics of the garbage in the GPGP, such as plastic type and age, demonstrate that plastic may endure in this environment (Van Sebille et al., 2012).
Plastic in the patch has been observed since the 1970s, and further calculations reveal that microplastic mass concentration is increasing exponentially—indicating that the input of plastic in the patch is larger than the output. This figure will continue to climb unless sources are reduced (The Ocean Clean Up, 2021).
5. A plastic medal for who pollutes most
A recent study published in April 2021 by Lober (2021) shows which countries were responsible for the greatest plastic pollution in the oceans. The investigation discovered that countries with poorly managed plastic trash, as well as rivers that flow into the oceans, were the primary source of plastic pollution in the oceans. Indeed, the interaction of these two factors determines whether a country contributes plastic to the oceans or not.
Asia is responsible for 81% of all ocean plastic. In this region, there are numerous rivers flowing into the sea. Plastic enters rivers and eventually goes into the ocean as a result of poor waste management. China and Indonesia are the primary suppliers of single-use plastic pollution in the oceans: bottles, packaging, and major bags. According to this report, the two countries are responsible for almost 5 million tonnes of plastic debris that end up at sea each year. They are coastal countries crossed by the world's major rivers, such as the Yangtze, Nile, and Amazon, or they are located on islands that drain the most plastic in marine habitats. The Philippines, representing around 1% of the global population, is responsible for 36.4% of the world's ocean plastic. The nation is home to seven of the ten rivers that contribute the most to plastic ocean pollution.
North America and Europe account for only 4.5% and 0.6% of ocean plastic, respectively. Reducing plastic use in these locations is still crucial but here plastic is more likely to end up in landfills rather than the ocean. The United States, for instance, produces more plastic waste per capita, but much of it does not end up in the ocean because most of the states are landlocked, and therefore a large portion of it ends up in landfills.
Among more economically developed countries, Malaysia is the biggest ocean polluter with plastics followed by Turkey and Trinidad & Tobago.
Instead, Japan and the United Kingdom could serve as a model for how island nations can keep plastic out of the ocean through waste management.
6. A gold medal for who tries to solve the problem
Fortunately, as the problem becomes more acute, new communities are emerging to limit the impact of plastic on our earth and several firms are committed to tackle this issue.
Among them, the first three taking the lead are:
a) The Ocean Cleanup: the primary goals of this project include tackling 1000 of the world's most contaminated rivers and reducing floating ocean plastic by 90% by 2040. Accordingly, they are committed to use their technology, knowledge, and experience to intercept plastic in rivers, before it could reach the oceans, as well as developing methods aimed at removing existing plastic—debris that have been accumulating for decades in collaboration with enterprises, governments, and individuals worldwide.
b) The Great Bubble Barrier: this start-up aims to remove as much plastic from the world's running inland waterways. It hopes to improve water quality and consequently the quality of life for humans and animals.The GBB filters plastic from waterways by using bubble screens. This is how it intends to reintroduce plastic into the supply chain in a sustainable manner. Furthermore, they wish to raise public awareness of the plastic problem in order to reduce the accumulation of plastic in rivers.
c) Inno Plastic (EU level): In-No-Plastic (Innovative methods to marine plastic litter prevention, removal, and reuse) is a three-year EU-funded project that aims to develop and demonstrate nano-, micro-, and macro-plastic clean-up solutions in aquatic ecosystems. The research is supported by the Horizon 2020 Research and Innovation programme, as part of a pilot action to remove marine plastics and trash. Moreover, this topic supports the European Plastics Strategy for a Circular Economy. The strategy used is a combination of social and technical techniques which involves comparing existing plastics removal procedures with multiple new technologies at various testing locations in Europe and the Caribbean.
2. CLEANUP TECHNOLOGIES
The alarming nature of ocean plastic is undisputed. However, it is more constructive to focus on what has been done so far to tackle this problem. As a matter of fact, several technologies have been developed to clean up oceans, by acting more or less upstream in the plastic pollution chain: from cleaning wastewater before it flows into the sea, to collecting plastic from rivers, to removing it from the great garbage patches that form in the oceans. We will now proceed to analyze some of the most interesting operational projects.
The best-known organization committed to ocean plastic removal is arguably The Ocean CleanUp, a Dutch company founded in 2013 by a teenage engineer, Boyan Slat, who developed a system (called System 002) that simulates a fake coastline to cumulate plastics. It does so by analyzing the patch’s internal currents and thus identifying hotspots of plastics: the cleanup system then positions itself close to these hotspots and exploits the different speed between the plastic patch and the cleanup system. This way, the System is able to concentrate highly diluted plastics and to gather greater quantities of fragments. Collected plastic (whose dimensions span from a few millimeters to several meters) is then trapped in a ‘retention zone’ and hauled on deck in order to be disposed of on ground.
A great advantage of this method is that it does not present significant risks for the environment, according to an independent Environmental Impact Assessment (EIA). What is more, the program foresees a complete offset of carbon emissions and monitoring of the interactions between the System and the environment.
Drum screen systems are also relatively common, such as the Archimedean Drum Screw (developed by FishFlow Innovations) and Roto-Sieve drum screens. Generally speaking, drum screen technologies are used for the screening of solid impurities in pressure sewer systems by a screwing mechanism that rotates a drum screen and thus separates litter from the intake water. They have several applications, among which stands plastic debris collection. In particular, “the bulk volume of water passes through the screen mesh of the drum and enters the industrial facility, whereas the screw carries fish and other solid objects over the length of the drum towards an outlet” (fishflowinnovations.nl). Moreover, the features of the installation, such as its design, the area of filtration and the mesh size, are based on local specifications, including flow rate and type of suspended solids. This allows greater flexibility and adaptation to specific conditions.
Other than being useful to eliminate plastic from oceans and rivers, this kind of technology respects marine life and avoids fish mortality. As a matter of fact, fish, jellyfish, and natural solid materials are returned to surface waters through side channels, without being damaged.
Some cleanup technologies are twice as environmentally friendly, as they use renewable energies to work. It is the case of Mr Trash Wheel, an imaginative system placed in the harbor of Baltimore (USA) in 2014, that is fully powered by solar and hydro power. What is more, not only does it collect plastic, but it also removes oil slicks. In particular, this technology uses containment booms (i.e., temporary floating barriers) to funnel plastic into its ‘mouth’. A rake then leads the garbage onto a conveyor belt and eventually into a floating dumpster. The plastic is then incinerated to create electricity. Although incineration is not the most eco-friendly solution, it is the best alternative for the moment, since this technology cannot yet distinguish recyclable plastic from other kinds of litter. But how does all this work? Very simply indeed: a wheel powered by the river’s current serves as an engine, and when the current is not strong enough, it moves thanks to solar energy.
Another cleanup method uses flocculation, a chemical process which consists in the aggregation of fine particles into flocs as a result of cohesive forces and organic polymers and coatings. It makes plastic collection easier in two ways: firstly, it induces an increase in particle size because particles stick together; at the same time, it causes a decrease in particle density because the flocs contain pores filled with ambient water (Andersen et al, 2021). Flocculation can also be facilitated by the use of ultrasound clustering, which agglomerates nano and micro plastics by making them align on ultrasound waves and then cluster into conglomerates which will then undergo flocculation. This principle is used, for instance, by Wasser 3.0, winner of the “New Economy Award 2022”. However, it focuses on a more upstream cleanup, namely concerning industrial and municipal wastewater.
Some other systems are based on extremely simple principles. It is the case, for example, of Seabin V5, which is nothing more than a floating garbage bin? skimming the surface of the water by pumping water inside. The great advantage of this device is that it is able to detect and filter micro plastic as well. However, it does not operate in deep waters.
Needless to say, ocean cleanup is closely connected to river cleanup, since a great part of ocean plastic (between 1.15 and 2.41 million metric tons per year, according to the Ocean CleanUp data) comes from rivers. Some original technologies developed systems specialized in river plastic pollution, such as The Great Bubble Barrier developed by the homonymous Dutch company. The plastic is directed to the surface by a perforated tube that pumps air, thus creating a screen of bubbles which is strong enough to drive plastics to the surface. At the same time, this system is harmless for fish and does not hinder boat navigation.
Last but not least, surveillance technologies through cameras, apps, or even satellites are always playing a growing role. More indirectly, software technologies can contribute to the cleanup of oceans by gathering precious data, namely GPS and blockchain. They prove particularly useful to track and trace litter in the circularity value-chain. Furthermore, apps now allow more efficient and large-scale hand-picking from beaches. Indeed, we must not forget that all the ‘side technologies’ that monitor plastic flows and collect data play a role which is as important as that of the collecting system themselves.
The advantage of these technologies is that in most cases they are eco-friendly by nature. In other words, in addition to being programmed to clean up oceans from plastic, they are conceived to cause the least harm possible to the marine environment. Some of them intend to reabsorb the CO2 emitted during operations, others are powered by renewable resources or have mechanisms that take into account the safety and welfare of marine life. Some of them were developed by organizations that explicitly operate for the achievement of the 2030 UN agenda Sustainable Development Goals (SDG). In particular, the Goals involved are SDG 6 on Clean water and sanitation, SDG11 on Sustainable Cities and Communities and SDG14 on Life below water.
Under a financial and technical point of view, however, their application may not be as easy as it is necessary. Firstly, in some cases they exploit advanced or recently developed technologies, which makes it hard for developing countries to build them in loco. A dependence from imports will inevitably increase the price for such technologies. Moreover, sometimes their high degree of innovation needs long testing processes, and their application on a large scale still suffers some setbacks.
However, financially speaking, removing plastic from oceans would mean a significant economic gain. As a matter of fact, environmental damage to marine ecosystems is estimated to equate to some $13bn per year (WorldFinance.com), especially in the fishing industry.
Considering that countries whose seas are most affected by ocean plastic pollution belong to ‘the global South’ (namely Latin America and South-Pacific Asia), while most of cleanup projects are developed in countries of ‘the global North’ (such as Germany, Netherlands, and the USA), it may be argued that cooperation involving local communities, or international cooperation among NGOs, is necessary for them to be efficient and accessible. In June 2021, for instance, the Global Plastic Action Partnership and UpLink launched the Global Plastic Innovation Network (GPIN), which focuses on innovative systems to tackle plastic pollution.
Lastly, we must bear in mind that despite their innovative potential and their undisputable utility, marine cleanup technologies need to be accompanied by a more radical and systemic change in the global economy. In particular, they are usually powerless against micro plastics, that are harder to detect and easily pass through the filtration systems. A change towards a circular economy, renewable energies, better waste management and the abandonment of plastic production is therefore of the utmost importance to reducing plastic pollution
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