Microplastics in the environment: sources, consequences and solutions

Introduction

In recent decades, the problem of plastic pollution has become one of the most discussed topics in the environmental sphere. Every year more and more plastic waste ends up in nature, and among them microplastics - particles smaller than 5 mm, which can be both primary (e.g. pellets used in production) and secondary (formed as a result of destruction of large plastic products) - occupy a special place.

Experts estimate that millions of tonnes of plastic waste end up in oceans, rivers and soils, and that microplastics are spread across the planet, including the most remote corners such as polar regions and deep-sea ecosystems. This raises serious concerns as microplastics become an integral part of the environment where they can have a negative impact on flora and fauna.

Microplastics is not only an environmental problem but also a social problem. It threatens food security, affects human health through food chains and can cause economic losses in the fishing and tourism industries. Studies show that microplastics can accumulate in marine creatures and its potential impact on human health still requires further research.

In addition, how to stop the spread of microplastics and minimise their environmental impact is becoming an increasingly urgent issue. Many organisations, scientists and environmental activists are working to find solutions to reduce plastic production, improve disposal systems and introduce alternative materials.

Thus, the problem of microplastics is complex and multidimensional, requiring careful study and active intervention. In this article we will look at the sources of microplastics, their impact on ecosystems and human health, and possible solutions to this global environmental problem.

Sources of microplastics

Microplastics enter the environment through a variety of sources that can be roughly categorised into two groups: primary microplastics, which are purposefully created, and secondary microplastics, which arise from the decomposition of larger plastic products. Let us consider them in detail:

Primary microplastics are plastic particles that are produced in micro-sizes and are initially used in everyday products or manufacturing processes. The main sources of primary microplastics include:

• Cosmetics and household chemicals: Some skin scrubs, toothpastes, shower gels, and detergents use microplastic granules. These pellets are easily washed away by water and then end up in sewage systems and, if not captured by sewage treatment plants, end up in rivers and oceans. Despite growing awareness of the problem, such micro-pellets continue to be used in products, especially in countries with weaker environmental requirements and standards.
• Microfibres from synthetic clothing: Clothing made from polyester, nylon, acrylic and other synthetic materials release microscopic fibres when washed. It is estimated that a single wash can release up to 700,000 microfibres, which are so small that sewage treatment plants cannot always trap them. These fibres end up in aquatic ecosystems where they accumulate in marine animals and can be passed down the food chain.
• Industrial pellets and powders: Industrial plastic pellets (pallets), known as ‘nurdles’, are used in the manufacture of plastic products. They are often released into the environment during the transport and processing stages, especially if there are spills or disruptions in logistical processes. These pallets are one of the largest sources of virgin microplastics.
• Rubber dust from tyres: When car tyres are worn during driving, microscopic rubber particles containing polymers are released. These particles are deposited on roads and then washed by rainwater into drains where they can pollute rivers and seas.

Secondary microplastics are formed when large plastic objects break down into smaller particles due to external factors such as solar radiation, water and physical abrasion. Major sources of secondary microplastics include:

• Single-use plastics: Plastic bags, bottles, packaging and other single-use items that are mass-produced around the world break down into micro-particles over time. This process is called photodegradation - when exposed to ultraviolet light, large pieces of plastic become brittle and break down into small fragments. These fragments can be spread by wind and water, ending up in rivers, oceans and soil.
• Fishing nets and equipment: Abandoned or lost fishing nets made of strong synthetic materials also break down and become a source of microplastics. These materials persist in the marine environment for long periods of time, continuing to release fine particles that have negative impacts on marine ecosystems.
• Building materials and paints: Some building materials, such as insulating foams and paints used to coat ships, buildings and other objects, also degrade over time and release microplastics. In particular, antifouling paints that prevent algae and barnacles from fouling ships contain polymers that gradually degrade in seawater.
• Plastic waste in landfills: Plastics that end up in landfills are slowly broken down by sunlight and atmospheric conditions. These processes break down large plastic items into micro-particles that can then make their way into soil and water bodies.

Unobvious sources of microplastics

In addition to the obvious sources, there are lesser-known pathways for microplastics to enter the environment:

• Atmospheric deposition: Studies show that microplastics can be carried significant distances by air currents and deposited in remote regions, including mountains and the Arctic. Plastic dust also accumulates in large cities where concentrations are higher due to car traffic and heavy use of plastic materials.
• Soil contamination through fertilisers: Fertilisers made from recycled organic waste (e.g. biomass compost) may contain microplastics. This plastic gets into the soil and then into plants and groundwater.

Pathways and impacts of microplastics

One of the key sources of microplastics are plastic products that are gradually degraded by various environmental factors. When exposed to sun, wind, water and biological processes, plastic gradually breaks down into tiny particles called microplastics. This process can occur both in landfills, where plastic waste can remain for decades, and in natural environments such as beaches, rivers and lakes. Photodegradation - degradation by sunlight - plays a crucial role in the plastic degradation process, which is particularly active in coastal areas and open water spaces. However, microplastics are not only formed from large plastic objects. The production of plastic products is also accompanied by the formation of so-called primary microplastics, which are already microscopic in size. These microparticles are used in production processes such as cosmetics and cleaning products and enter the environment directly.

Water Resources:

Microplastics are distributed through many pathways, and one of the most significant is the aquatic environment. Rivers, seas and oceans are in fact becoming the main transport routes for microplastics, which enter water bodies through both wastewater and sediments. Industrial emissions, untreated wastewater from factories and plants, polluted areas in cities, and motorways are all sources through which microplastics enter rivers. This also includes wastewater discharges from municipal wastewater treatment plants, where microplastics are not completely removed in the treatment process. The microparticles are then transported by rivers to the seas and oceans, where they can travel great distances due to ocean currents.

In aquatic ecosystems, microplastics can be found in a variety of places: floating on the surface of the water, settling to the bottom, or suspended in the water column. These particles can be transported by water currents thousands of kilometres from their original point of entry into a water body. This results in the accumulation of microplastics in specific areas, such as so-called ‘plastic islands’, of which the Great Pacific Garbage Patch is an example. These areas are plastic waste traps, and microplastics make up a significant portion of the pollutants in these areas. Due to the constant movement of water masses and the circulation of ocean currents, microplastics continue to spread, polluting even the remotest parts of the world's oceans. There are an estimated 5.25 trillion plastic particles floating in the world's oceans, weighing a total of 270,000 tonnes.

Microplastics have a significant impact on aquatic organisms. Microplastic particles often enter the digestive systems of marine and freshwater inhabitants such as fish, shellfish, plankton and birds. Many of these organisms mistake microplastics for food, causing plastic particles to accumulate in their bodies. For example, fish that feed on zooplankton may unintentionally consume microplastics that are similar to their natural food. Plastic particles can clog the animals' digestive systems, making it difficult for them to eat normally and can lead to starvation and death. Particularly susceptible are filter feeders such as clams and shrimps, which, when filtering water, capture not only microorganisms but also microplastics, which further accumulate in their bodies.,

A study on the prevalence of microplastic particles in the digestive tract of marine species revealed the presence of microplastics in 16 different species of marine organisms that are eaten by humans. Samples were taken from the most important ports on the Pacific coast of Ecuador, in four provinces: Manabi, El Oro, Esmeraldas and Santa Elena.

The marine species involved in the study were classified according to their feeding type: carnivorous, planktonivorous and detritivorous. Fifteen samples (n = 15) were collected and analysed for each of the 16 species. This study quantified the level of microplastic contamination in marine organisms consumed by humans, highlighting the threat posed by ocean pollution and its impact on food chains.

Microplastics are also found in food and drinking water, raising additional concerns for human health. Current research shows that microplastic particles can make their way into drinking water from both natural sources and from bottled and tap water. This indicates that the pathways of microplastics are so diverse that even treated water can contain microplastic particles. In food, microplastics are found through food chains when animals and marine life ingest these particles. People who consume these products are exposed to microplastics and the toxic substances associated with them, causing health risks.

The toxic impact of microplastics is also a serious problem for ecosystems. Microplastics can adsorb various chemical pollutants such as heavy metals, pesticides and other toxic substances on their surface. When marine organisms ingest microplastics, these hazardous substances can penetrate their tissues, causing harmful health effects. These chemical contaminants then spread through the food chain, accumulating in the bodies of larger animals, including humans. Humans who consume seafood may be exposed to toxic substances associated with microplastics, raising serious health concerns. A study by data journalism agency Orb found that almost all tap water in the world contains microscopic plastic fibres. This raises serious concerns about the effects of global plastic pollution on the planet. According to the study, about 83 per cent of tap water samples showed the presence of microplastics. The samples were taken from more than ten countries on all continents. Although contamination levels varied by region, microplastics were found in more than 72 per cent of tap water samples in all locations tested, including Europe and Asia.

Atmospheric air

Microplastics have a negative impact not only on aquatic but also on terrestrial ecosystems. Air masses play an important role in the spread of microplastics as particles are lifted into the atmosphere as a result of the physical wear and tear of plastic materials, car tyres and the breakdown of packaging. These microparticles can travel long distances with wind currents and then settle on the ground or water surfaces with rain. Numerous studies have shown that microplastics are found in precipitation even in remote mountainous areas where there are few sources of pollution. This fact points to the global nature of the problem of microplastics spreading.

In a study conducted in Denmark and published in 2019 in the journal Scientific Reports, the research team demonstrated how microplastics can penetrate the human respiratory tract. To do this, they developed a special mannequin that was fitted with a glass-aluminium breathing system and a heating system so that its temperature matched that of the human body. The mannequin was placed in flats in the city of Aarhus for 24 hours to analyse the level of microplastics in the air. The results of the study showed that between 4 per cent and 77 per cent of the total air volume in the flats was contaminated with microplastics. This means that in some parts of the room, the concentration of microplastics can significantly exceed the permissible limits, and every breath a person takes can be accompanied by plastic particles entering the respiratory tract. The vast majority of these microparticles came from synthetic polymers used in clothing, furniture and household products. In addition, the study confirmed that microplastics are much finer than other air pollutants such as dust or skin flakes, increasing their ability to penetrate the lungs and therefore increasing health risks. These findings have been confirmed by other studies. For example, a 2020 study conducted in London found between 575 and 1,008 microplastic particles per square metre of air, and a 2019 study conducted at snow levels in the Alps and Arctic found up to 1,760 microplastics per litre of air. This indicates the ability of microplastics to spread across the planet, even to the remotest corners of the Earth.

Another study from Paris found that plastic fibres, the main source of microplastics in the air, account for a significant proportion of global plastics production. They can also carry chemicals on their surface, exacerbating their health effects by causing inflammation in the lungs and increasing the risk of infertility and cancer.

Land resources

Microplastics enter the soil through organic fertilisers containing composted plastic waste, sewage sludge and the decomposition of plastic waste in landfills. As a result, plastic particles accumulate in the upper layers of the soil, which disturbs its structure and chemical composition. These microparticles can affect the water-holding properties of the soil, reducing the availability of water to plants. This negatively affects the growth and development of plants that cannot receive sufficient water. In addition, microplastics affect soil microorganisms, which play an important role in nutrient cycling. Disturbance of their activity can lead to a slowdown in the decomposition of organic matter and a decrease in soil fertility.

The negative impact of microplastics is also related to their ability to penetrate groundwater. Plastic particles can seep through the soil and into aquifers, contaminating drinking water sources. This is particularly relevant in agricultural areas where the use of fertilisers and composts containing plastic particles is particularly common. Thus, microplastics have a multifaceted impact on soil ecosystems, worsening conditions for plants, microorganisms and other living things.

Biodiversity

Microplastics have become a new habitat for a variety of living organisms, including protozoan algae, bryozoans, crustaceans, isopods, molluscs, marine worms and bacteria. These organisms are able to attach to plastic particles, which has two important consequences. Firstly, the additional substrate promotes an increase in biomass and concentration of life in the water volume. Second, together with microplastics, these organisms can move through the oceans, populating new areas and potentially spreading viruses and bacteria.

Microplastics enter food chains when they are consumed by animals ranging from zooplankton to fish and birds. Plastic particles can accumulate in the tissues of living organisms, which can cause serious problems. Plastic often contains toxic additives such as colouring agents and flame retardants, which when ingested into the digestive system of animals can cause organ damage, intestinal inflammation and adversely affect reproduction.

In addition, microparticles readily absorb other toxic substances, such as pesticides and dioxins, and can release them into the organism into which they penetrate. This poses additional risks to animal and human health. Plastic particles can also provide a medium for invasive species, viruses and bacteria, making them potentially harmful to both ecosystems and human health.

Microplastics in Uzbekistan

Terrestrial sources of microplastics in the aquatic environment, including freshwater, can arise from a variety of activities, infrastructure and land use. For example, runoff from road surfaces due to road marking paint failure and tyre wear debris has been a significant contributor. Agricultural runoff has also been identified as a potential source of microplastics in freshwater environments, particularly where sewage sludge has been deposited on land or where plastics have been used in agriculture, for example for mulching.

Rivers, wastewater treatment plants and canals can be sources of microplastics within Tashkent city limits. The total number of canals in Tashkent is 129 (37 of them are covered with earth) and their length is more than 412 kilometres.

About 33,000 tonnes of plastic containers are imported into Uzbekistan every year. PET Recycling Group. produces PET flakes and pellets and has the capacity to recycle 20 tonnes of bottles per day. Accordingly, if one company operates at full capacity for about 300 days per year, 6,000 tonnes (18%) of plastic in Uzbekistan will be recycled in 1 year. In order to process 33,000 tonnes of plastic containers, 6 plastic recycling enterprises with the capacity to process 20 tonnes of plastic per day are needed.

Scientists from Tomsk State University (TSU) together with colleagues from the Institute of Zoology of the Academy of Sciences of Uzbekistan, Navoi State Pedagogical Institute and Andijan State University conducted the first study on microplastic pollution of Uzbekistan's rivers, the TSU press service reported.

The scientists analysed water samples from tributaries of the Syr Darya, as well as from the Chirchik and Karadarya rivers. Yulia Frank, director of the Centre for Microplastics Research at TSU, said that the main particles found in Uzbekistan's rivers were fibres. Their share in the water of the Karadarya and Chirchik rivers was 89% and 95%, and in the bottom sediments of the Syr Darya tributaries - 86% and 84%, respectively. This dominance of fibres indicates the input of pollution through domestic wastewater and discharges from sewage treatment plants.

Analysis of polymer composition showed that polyethylene terephthalate, contained in polyester, the main material for clothing and textiles, was predominant in water and bottom sediments. The textile origin of pollution was particularly pronounced in the Karadarya River, where viscose and nylon fibres were also found.

These data became the first confirmation of the presence of microplastic pollution of the Syr Darya tributaries on the territory of Central Asia.

Ways to tackle the problem

The accumulation of plastic in the environment is rapidly increasing due to its low degradability and inefficient disposal methods. In 2016, global plastic production was 322 million metric tonnes, of which 39.9% in Europe was used for packaging. An estimated 4.8 to 12.7 million metric tonnes of improperly disposed plastic waste entered the oceans in 2010. When exposed to sunlight and temperature factors, plastic breaks down, turning into particles smaller than 5mm, known as recycled microplastics.

Polyethylene (PE), polypropylene (PP) and polystyrene (PS) are the most common types of plastic in the oceans. Their behaviour in nature depends on their density and their ability to adsorb microorganisms and chemicals, which enhances their toxicity. In coastal areas, especially near industrial areas and megacities, concentrations of microplastics are particularly high. In one Swedish harbour, up to 102,000 microplastics per cubic metre of water have been found. In the open ocean, plastic waste accumulates as a result of the movement of winds and currents, forming large litter cycles.

1. Regulation and legislative measures

Government initiatives play a key role in combating microplastic pollution. The main government regulatory measures include:

• Banning the use of virgin microplastics in products: Some countries have already introduced bans on the use of microplastic pellets in cosmetics and household chemicals. Expanding such bans internationally to include clothing, detergents and other consumer products could significantly reduce primary microplastic emissions into the environment.
• Regulating the production and use of plastics: Introducing stricter standards for the recycling and production of plastic products can help reduce microplastic leakage at the production and logistics stage. It is also important to develop regulations on the use of more environmentally friendly alternative materials.
• Developing separate waste collection and recycling systems: An effective system for collecting, sorting and recycling plastic waste can significantly reduce the amount of plastic entering the environment and degrading to microplastics. Environmental awareness programmes and the promotion of recycled materials play an important role here.

2. Тechnological innovations

Technological solutions can play an important role in the fight against microplastics. Some promising approaches include:

• Filtration systems for wastewater treatment: Improved wastewater treatment technologies using filters that can trap microplastic particles will help reduce their release into rivers and oceans. Some countries are already developing special filtration systems for effluent from laundries and domestic washing machines.
• Creating biodegradable materials: Developing and implementing materials that can fully biodegrade in nature, leaving no microplastics behind, is a key step. There are already projects to create plastics based on organic matter such as maize or algae, which do not form microplastics when they decompose.
• Capturing microplastics in oceans and rivers: Some projects aim to capture microplastics from water. For example, special barriers or mesh structures installed in rivers and estuaries can prevent microplastics from entering the ocean. Plastic litter collection systems are also being installed in the ocean to partially address the problem locally.

3. International co-operation

Microplastics is a global problem and its solution requires a concerted international effort:

• International agreements and conventions: There is a need to expand international environmental treaties, such as the Basel Convention, which regulates the movement of hazardous waste, to include microplastics management. Countries should jointly develop strategies to reduce the use and production of plastic, and implement programmes to control marine pollution.
• Exchange of experience and technology: Countries should share best practices and technologies to prevent microplastic pollution. This is particularly important for emerging economies where lack of resources and technology hinders effective pollution control.
• Supporting ocean cleanup projects: International organisations and foundations can sponsor global initiatives to clean up plastic litter in oceans and coastal zones. For example, The Ocean Cleanup project aims to create networks to remove plastic from the ocean and prevent it from entering aquatic ecosystems.

4. Changing consumer habits

Each individual's behaviour and choices largely determine the amount of microplastics emitted into the environment. Key ways to change consumer habits include:

• Reducing the use of single-use plastic: One of the simplest and most effective ways to reduce plastic litter is to reduce the use of single-use plastic products such as bags, bottles, utensils and packaging. Instead, you can use reusable alternatives such as cloth bags, glass bottles or steel containers.
• Proper disposal of plastic: Consumers should be informed on how to properly dispose of plastic products to minimise their impact on the environment. This includes sorting waste, using plastic collection points for recycling and participating in environmental waste collection events.
• Conscious clothing choices: Washing synthetic clothing is a major source of microplastics. To reduce its release, you can choose clothes made of natural materials (cotton, linen, wool) or use special filters for washing machine drains.

5. Environmental education and awareness

The microplastics issue requires a global increase in environmental literacy. This includes:

• Education programmes: Widespread public awareness of the effects of plastic and the importance of recycling should be a priority for environmental organisations, governments and businesses. School and university programmes should include information on the impacts of microplastics and measures to reduce them.
• Supporting environmental initiatives: Citizen participation programmes in litter picking, beach, river and park clean-ups can increase awareness and involvement of people in addressing the microplastic problem.

Conclusion

The problem of microplastics in the environment is one of the most serious global environmental threats of our time. Its presence affects all ecosystems - aquatic, terrestrial and atmospheric - negatively impacting biodiversity, human health and the sustainability of the planet. Extremely persistent, microplastics accumulate in food chains, transport toxic substances and destroy ecosystems, contributing to biodiversity loss and climate change.

Effectively addressing this problem requires an integrated approach that includes government regulation, reduction of single-use plastic consumption, introduction of innovative technologies for recycling and cleaning, and active community participation in reducing plastic use and proper waste management. Short-term measures such as bans or taxes on harmful plastic products, public awareness and the development of biodegradable materials will help reduce pollution in the short term. Medium-term steps, including improving waste collection and recycling systems, converting plastic into energy and reducing industrial waste, will create a more sustainable management system. In the long term, the use of renewable energy and biodegradable materials, the introduction of ecodesign and international co-operation will be important.

As plastic pollution has no borders, it requires countries around the world to join forces to successfully combat it. Working together to improve waste management systems and clean up the oceans will help prevent further ecosystem destruction and create a more sustainable future for the planet and generations to come.