Microplastics trapped in soil aggregates of different land-use types: A case study of Loess Plateau terraces, China

Existence and fate of microplastics in terrestrial environment: A global fretfulness and abatement strategies

Widespread use of plastics in consumer products, packaging, cosmetics, and industrial and agricultural production has resulted in the ubiquitous occurrence of microplastics in terrestrial environment. Compared to the marine environment, only limited studies have investigated the microplastics pollution and associated risk in terrestrial environment. The present review summarizes the global distribution of microplastics in terrestrial environment, their transport pathways and fate, risk to ecosystem and human health, and abatement strategies. Small particle sizes (<500 μm); fragment, fiber, and film shapes; transparent and white color; polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET) polymers were the major characteristics of the microplastics found in terrestrial environment. Microplastics in soils negatively affect soil organisms, while the impact of microplastics in terrestrial environment on human health is poorly understood, which needs to be explored further as there is clear evidence on their presence in human bodies. The removal of microplastics from soil environment is quite complex and costly, thus prevention of their releases is preferable. Among the existing abatement options, biodegradation, which harnesses bacterial strains to degrade microplastics through enzymatic hydrolysis, hold promise for terrestrial environment. Strengthening global cooperation, implementing timely policies on plastic use and recycle, and developing new technologies for control of microplastics are recommended to reduce the pollution in terrestrial environment. Global effort on reducing plastic wastes and enhancing their management is imperative, while substitution with biodegradable plastics could help minimize future accumulation of microplastics in terrestrial environment.

Residual mulch-film characteristics affect heavy metal migration of different soil layers in the subtropical croplands of China

In recent years, as the abundance of residual mulch film (RMF) in agricultural soil continues to increase, whether the adsorption capacity of its surface affects the migration of heavy metals is a topic of current interest for scholars. Herein, this study investigated the distribution of RMF abundance and metal concentration in different soil layers of 75 plastic-mulching croplands in subtropical China; meanwhile, we also explored the associations of RMF characteristics with metal concentration. The results showed that land type, film mulching amount, and film mulching time were the main factors affecting RMF abundance, distribution, and particle size composition. The highest abundance of RMF was found in the garden soils (910 n·kg-1) with more than 15 years mulching period and more than 19.5 kg hm-2 of annual mulch amount. The lowest abundance of RMF was occurred in the group of field and conservation agricultural land (237 n·kg-1). Moreover, the concentrations of metals in soil, especially Cd, Cr, Cu, and Pb, were closely related to the extent of RMF contamination in the soil environment. In the 0-10 cm and 10-20 cm soil layers, microplastic abundance exhibited a negative correlation with Cr and Cu concentrations and a positive correlation with Pb concentration. Based on the above findings, it is demonstrated that RMF significantly influences the mobility of metals in soil via adsorption processes, with potential synergistic effects between RMF and heavy metals posing a heightened risk to the soil environment.

Characteristics of microplastics and their abundance impacts on microbial structure and function in agricultural soils of remote areas in west China

As an emergent pollutant, microplastics (MPs) are becoming prevalent in the soil environment. However, the characteristics of MPs and the response of microbial communities to the abundance of MPs in agricultural soils in West China still need to be elucidated in detail. This study utilized the Agilent 8700 Laser Direct Infrared (LDIR) to analyze the characteristics of small-sized MPs (20-1000 μm) in soils from un-mulched and mulched agricultural fields in West China, and illustrated their correlation with microbial diversity. The results revealed a higher abundance of MPs in mulched soil ((4.12 ± 2.13) × 105 items kg-1) than that in un-mulched soil ((1.04 ± 0.26) × 105 items kg-1). The detected MPs were dominated by fragments, 20-50 μm and Polyamide (PA). High-throughput sequencing analysis indicated that alpha diversity (Chao1 and Shannon indices) in the plastisphere was lower compared to that in soil, and varied significantly with MPs abundance in soil. As the abundance of MPs increased, the proportion of soil about the degradation of organic matte and photoautotrophic taxa increased, which showed enrichment in the plastisphere. Functional predictions further indicated that MPs abundance affected potential soil functions, such as metabolic pathways associated with the C and N cycling. The plastisphere showed higher functional abundance associated with organic matter degradation, indicating higher potential health risks compared to soil environments. Based on the RDA analyses, it was determined that environmental physicochemical properties and MPs abundance had a greater impact on fungal communities than on bacterial communities. In general, the abundance of MPs affected the microbial diversity composition and potentially influenced the overall performance of soil ecosystems. This study offers empirical data on the abundance of MPs in long-term mulched agricultural fields and new insights for exploring the ecological risk issues associated with MPs.

Using machine learning to reveal drivers of soil microplastics and assess their stock: A national-scale study

The issue of microplastic (MP) contamination in soil is a significant concern. However, due to limited large-scale studies and stock assessments, our understanding of the drivers of their distribution and fate remains incomplete. To address this, we conducted a comprehensive study in China, collected MP data from 621 sites, and utilized machine learning techniques for analysis. Our findings revealed 9 key factors influencing the distribution of soil MPs, highlighting their nonlinear influence processes. Among these factors, atmospheric deposition emerged as the most dominant driver, while wind and precipitation could lead to the transformation of soil from a sink to a source of MPs. MP concentrations in Chinese soils vary from 1.4 to 4333.1 particles/kg, with human activities significantly affecting their distribution, resulting in higher concentrations in the east and lower concentrations in the west. The estimated MP stock in Chinese soils is 1.92 × 1018 particles, equivalent to a mass of 2.11-8.64 million tonnes. This stock alone surpasses that found in global oceans, making global soil the largest reservoir of MPs. Overall, this study enhances our understanding of the environmental behavior of MPs and provides valuable data and theoretical support for the prevention, control, and management of this contamination.

Effects of soil properties and land use patterns on the distribution of microplastics: A case study in southwest China

Microplastic pollution in the soil environment is of great concern. However, the current research on microplastics (MPs) in Southwest China mainly focuses on their distribution characteristics and sources in soil, making the understanding of the soil properties and land use patterns influencing soil MPs insufficient. In this study, the abundance and distribution characteristics of MPs in the soil of different land use patterns in Guizhou Province were determined. The results revealed that the average abundance of MPs in soils was 2936 items/kg, ranging from 780 to 9420 items/kg. The MPs were mainly small particle size (0-0.5 mm), granular, and black, accounting for 87.5%, 36.6%, and 82.2%, respectively. The most common polymer types of MPs were polypropylene, polyethylene terephthalate, and polyethylene, which accounted for 20.4%, 16.8%, and 16.4%, respectively. As soil bulk density increased, microplastic abundance and small particle size decreased. Soil microplastic abundance slightly decreased with increasing soil porosity. The abundance of MPs increased with the increase in soil pH, but no significant correlation was observed between soil organic matter content and microplastic abundance. pH was the major factor that affected the microplastic distribution, which accounted for 32.5%. This study provides insight into the distribution and influencing factors of soil MPs and also provides a theoretical basis for subsequent research on soil microplastic pollution.

Occurrence characteristics and risk assessment of microplastics in agricultural soils in the loess hilly gully area of Yan' an, China

Large amounts of microplastics accumulated in the soil of agricultural fields with the rapid development of mulch agriculture. The enrichment of microplastics endangered the growth of crops and food security, and it also posed ecological risks. In this study, we investigated microplastics in a typical agriculture area of Yan' an City, in the loess hilly gully area of China. The characteristics of microplastics including their abundances, sizes, and types were measured through laser direct infrared spectrometer. The potential sources of microplastics were analyzed and the risk of soil microplastic pollution was evaluated. It was elaborated that the average abundances of microplastics in soil, water, and fertilizer were 4505 ± 435 n·kg-1, 91 ± 27 n·L-1, and 39,629 ± 10,114 n·kg-1, respectively. Microplastics with particle sizes < 100 μm accounted for >90 %. The smaller the particle size, the higher the content of microplastics. The top three polymers were polyethylene (PE, 37.4 %), polyethylene terephthalate (PET, 15.0 %), and ethylene vinyl acetate (EVA, 8.9 %), respectively. Agricultural mulch, plastic film, domestic waste, surface water irrigation, and organic compost were probably the potential sources of soil microplastics. The ecological risk evaluation showed that overall sampling sites had a minor ecological risk of microplastic pollution based on their abundance, while the polymer type showed a relatively high ecological risk for the investigated agricultural soils. Polyvinylchloride (PVC) and polymethylmethacrylate (PMMA) contribute considerably to the ecological risk, and their inputs to the farmland environment should be strictly limited. There was no significant carcinogenic risk to humans. This study would provide the basic reference for the current situation and risk assessment of farmland soil microplastics pollution in the loess hilly gully area of China.

Mechanism of polyethylene and biodegradable microplastic aging effects on soil organic carbon fractions in different land-use types

Microplastics (MPs) are widely present in terrestrial ecosystems, but knowledge about the aging characteristics of MPs in different land-use types and their impact on soil organic carbon fractions is still limited. Polyethylene (PE) and biodegradable MPs (Poly propylene carbonate and Polybutylene adipate terephthalate synthetic material (PPC + PBAT, Bio)), at 0 %, 0.03 %, and 0.3 % (w/w) dosages, were added to grassland, farmland, and facility soils for eight-week incubation. The aging degree of MPs was explored by quantifying the carbonyl index (CI). Soil organic C fractions such as SOC, particulate organic carbon (POC), mineral-associated organic carbon (MAOC), and microbial-derived C were analyzed. MPs underwent rapid aging after incubation, and the CI value for 0.03 % PE-MPs increased from 0.05 to 0.27 (farmland) and 0.26 (facility) (p < 0.05). The aging degree of 0.03 % and 0.3 % Bio-MPs was most significant in grassland, with CI decreasing by 46.6 % and 69.0 %, respectively. The CI of MPs were negatively correlated with their dosage. The 0.03 % and 0.3 % PE-MPs decreased soil organic carbon (SOC) content by 7.4 % and 8.2 % in grassland, and 3.0 % and 6.0 % in the facility (p < 0.05). POC content of farmland and facility soil was negatively correlated with PE-MPs' CI (p < 0.05). The 0.03 % PE and Bio-MPs decreased fungal necromass C (FNC) by 0.40 and 0.05 g kg-1 in grassland and 0.48 and 0.21 g kg-1 in farmland. Besides, the dosage of MPs regulated FNC content through soil pH, nutrients, and extracellular enzyme activity, either directly or indirectly, ultimately affecting the soil C pool. Therefore, this study demonstrates that MPs strongly affect SOC dynamics by influencing soil microbial enzyme activity and fungal necromass.

Microplastic interactions in the agroecosystems: methodological advances and limitations in quantifying microplastics from agricultural soil

The instantaneous growth of the world population is intensifying the pressure on the agricultural sector. On the other hand, the critical climate changes and increasing load of pollutants in the soil are imposing formidable challenges on agroecosystems, affecting productivity and quality of the crops. Microplastics are among the most prevalent pollutants that have already invaded all terrestrial and aquatic zones. The increasing microplastic concentration in soil critically impacts crop plants growth and yield. The current review elaborates on the behaviors of microplastics in soil and their impact on soil quality and plant growth. The study shows that microplastics alter the soil's biophysical properties, including water-holding capacity, bulk density, aeration, texture, and microbial composition. In addition, microplastics interact with multiple pollutants, such as polyaromatic hydrocarbons and heavy metals, making them more bioavailable to crop plants. The study also provides a detailed insight into the current techniques available for the isolation and identification of soil microplastics, providing solutions to some of the critical challenges faced and highlighting the research gaps. In our study, we have taken a holistic, comprehensive approach by analysing and comparing various interconnected aspects to provide a deeper understanding of all research perspectives on microplastics in agroecosystems.

Vertical distribution and weathering characteristic of microplastics in soil profile of different land use types

After deposition on the topsoil, microplastics (MPs) may be vertically migrated to deeper soil layers over time or eventually enter the groundwater system, leading to more widespread environmental and ecological issues. However, the vertical distribution of MPs in natural soils are not yet fully understood. In this study, we collected soil profiles (0-100 cm) from four different land use types on the west bank of Taihu Lake in China to investigate the vertical distribution and weathering characteristics of MPs. The average abundance of soil MPs followed the pattern of paddy field (490 ± 82 items/kg) > dryland (356 ± 55 items/kg) > tea garden (306 ± 32 items/kg) > woodland (171 ± 27 items/kg) in the 0-10 cm layer, and the abundance of MPs decreased linearly with soil depth (r = -0.89, p < 0.01). Compared to tea garden and woodland, MPs in dryland and paddy field have migrated to deeper soil layers (80-100 cm). The carbonyl index of polyethylene and polypropylene MPs increased significantly with soil depth (r = 0.96, p < 0.01), with values of 0.58 ± 0.30 and 0.54 ± 0.33, respectively. The significant negative correlation between MPs size and carbonyl index confirmed that small-sized MPs in deeper soil layers originated from the weathering and fragmentation of MPs in topsoil. The results of structural equation model showed that roots and soil aggregates may act as filters during the vertical migration of MPs. These findings contribute to a better understanding of the environmental fate of MPs in soil and the assessment of associated ecological risks.

Distribution of microplastic contamination in the major tributaries of the Yellow River on the Loess Plateau

Microplastic pollution in rivers had gained increased attention worldwide. However, the differences in microplastic characteristics among major tributaries of large rivers and the environmental factors influencing these characteristics remain uncertain. Through field investigation and indoor experiments, the distribution of microplastics and their driving factors were investigated at 96 sampling sites along the three main tributaries (Huangfuchuan, Wuding and Yan River) of the Yellow River in the Loess Plateau. The results revealed that the average microplastic abundance followed this order: Yan River (430.30 items kg-1) > Wuding River (145.09 items kg-1) > Huangfuchuan River (253.33 items kg-1). The abundance was lower than that in most parts of the world. There was a generally increasing trend in average microplastic abundance from upstream to downstream in the three rivers. The most frequently observed microplastic colors observed were black and white, and the most common polymer type were PE and PS in all three rivers. The dominant shape and size in the three rivers were fiber and particles measuring 0.5-5.0 mm, all accounting for more than half of the total microplastic content. The microplastic abundance, shape, and size were primarily influenced by mean annual precipitation and population density. This relationship can be attributed to the fact that increased population density driven by higher demand and consumption of plastic products, while augmented rainfall aggravated the occurrence of floods and provided conditions for plastic degradation and accumulation. This study will provide fundamental data for pollution assessing and ecological protection of the Yellow River, and provide a certain reference for future management and protection on the Loess Plateau.

Microplastics sequestered in the soil affect the turnover and stability of soil aggregates: A review

Plastic products have become ubiquitous in society, and entered various ecosystems due to the massive scale of production. The United Nations Environment Program (UNEP) has listed microplastics (MPs), which form when plastic remnants degrade, as a global emerging pollutant, and the association between soil pollution and MPs has become a popular research topic. This paper systematically reviews research focusing on MP-related soil pollution from the past 10 years (2012-2022), with the identified papers demonstrating that interactions between MPs and soil aggregates has become a research frontier in the field. The presented research provides evidence that soil aggregates are important storage sites for MPs, and that storage patterns of MPs within soil aggregates are influenced by MP characteristics. In addition, MPs affect the formation, turnover, and stability of soil aggregates through the introduction of fracture points along with diverse physicochemical characteristics such as composition and specific surface area. The current knowledge base includes certain issues and challenges that could be addressed in future research by extending the spatial and temporal scales over which microplastic-soil aggregate interactions are studied, unifying quantitative and qualitative methods, and tracing the fates of MPs in the soil matrix. This review contributes to enriching our understanding of how terrestrial MPs interact with soil aggregates, and whether they pose a risk to soil health.

Microplastic transport during desertification in drylands: Abundance and characterization of soil microplastics in the Amu Darya-Aral Sea basin, Central Asia

Desertification and microplastic pollution are major environmental issues that impact the function of the ecosystem and human well-being of drylands. Land desertification may influence soil microplastics' abundance, transport, and distribution, but their distribution in the dryland deserts of Central Asia's Amu Darya-Aral Sea basin is unknown. Here, we investigated the abundance and distribution of microplastics in dryland desert soils from the Amu Darya River to the Aral Sea basin in Central Asia at a spatial scale of 1000 km and soil depths ranging from 0 to 50 cm. Microplastics were found in soils from all sample locations, with abundances ranging from 182 to 17841 items kg-1 and a median of 3369. Twenty-four polymers were identified, with polyurethane (PU, 37.3%), silicone resin (SR, 17.0%), and chlorinated polyethylene (CPE, 9.8%) accounting for 64.1% of all polymer types. The abundance of microplastics was significantly higher in deep (20-50 cm) soils than in surface (0-5, 5-20 cm) soils. The main morphological characteristics of the observed microplastics were small size (20-50 μm) and irregular particles with no round edges (mean eccentricity 0.65). The abundance was significantly and positively related to soil EC and TP. According to the findings, desertification processes increase the abundance of microplastic particles in soils and promote migration to deeper soil layers. Human activities, mainly grazing, may be the region's primary cause of desertification and microplastic pollution. Our findings provide new information on the diffusion of microplastics in drylands during desertification; these findings are critical for understanding and promoting dryland plastic pollution prevention and control.

Vertical distribution and characteristics of soil microplastics under different land use patterns: A case study of Shouguang City, China

Soil microplastic pollution is ubiquitous, but the vertical distribution characteristics of microplastics in different land use types are unclear. In this study, the microplastic abundance, particle size, shape, color, and polymer type in 0-20 cm, 20-40 cm, and 40-60 cm soil layers of seven land use types (woodland, grassland, maize, wheat, cotton, polytunnel, and greenhouse) were systematically investigated in Shouguang City, a typical agricultural city in China. The results showed that the average microplastic abundance from top to deep for the three soil layers of Shouguang City were 1948.1 ± 992.5, 1349.4 ± 654, and 670.1 ± 341.6 items kg-1. In the top soil layer (0-20 cm), the abundance of microplastics in facility soils was significantly higher than in other land use types. In agricultural soils, microplastics were predominantly small size (<0.5 mm), films and fragments, PE and PP. The average microplastic abundance in deep soils (40-60 cm) of the seven land use types was 349.1 ± 62.8 (woodland), 284.9 ± 113.9 (grassland), 657.1 ± 127.1 (maize), 537.8 ± 137.4 (wheat), 851.4 ± 204.2 (cotton), 878.5 ± 295.7 (polytunnel), 1132.2 ± 304.5 (greenhouse) items kg-1, respectively, accounting for 11 % to 19 % in all three soil layers. The percentage of small size and pellet microplastics increased in deep soils (40-60 cm). Correlation analysis showed that soil environmental factors (pH, EC, total phosphorus, total nitrogen, and organic carbon) influenced to different extents the distribution, fragmentation, and transport of microplastics. The results of this study contribute to a better understanding of contamination and vertical distribution of soil microplastics in agricultural and non-agricultural soils, as well as provide important data for the development of preventive and management policies.

Effects of Microplastics on the Transport of Soil Dissolved Organic Matter in the Loess Plateau of China

Microplastics (MPs) pollution and dissolved organic matter (DOM) affect soil quality and functions. However, the effect of MPs on DOM and underlying mechanisms have not been clarified, which poses a challenge to maintaining soil health. Under environmentally relevant conditions, we evaluated the major role of polypropylene particles at four micron-level sizes (20, 200, and 500 μm and mixed) in regulating changes in soil DOM content. We found that an increase in soil aeration by medium and high-intensity (>0.5%) MPs may reduce NH4+ leaching by accelerating soil nitrification. However, MPs have a positive effect on soil nutrient retention through the adsorption of PO43- (13.30-34.46%) and NH4+ (9.03-19.65%) and their leached dissolved organic carbon (MP-leached dissolved organic carbon, MP-DOC), thereby maintaining the dynamic balance of soil nutrients. The regulating ion (Ca2+) is also an important competitor in the MP-DOM adsorption system, and changes in its intensity are dynamically involved in the adsorption process. These findings can help predict the response of soil processes, especially nutrient cycling, to persistent anthropogenic stressors, improve risk management policies on MPs, and facilitate the protection of soil health and function, especially in future agricultural contexts.

Response of microplastic occurrence and migration to heavy rainstorm in agricultural catchment on the Loess plateau

Microplastics have received widespread attention as an emerging pollutant in recent years, but limited studies have explored their response to extreme weather. This study surveyed and analyzed the occurrence and distribution of microplastics in a typical agricultural catchment located on the Loess Plateau, focusing on their response to heavy rainstorms. Microplastics were detected in all soil samples with an abundance of 70-4020 items/kg, and particles less than 0.5 mm accounted for 81.61 % of the total microplastics. The main colors of microplastic were white, yellow, and transparent, accounting for 38.50 %, 32.90 %, and 21.05 % respectively, and the main shapes were film and fragment, accounting for 47.65 % and 30.81 %. Low density polyethylene was the main component of microplastics identified using Fourier transform infrared spectrometry. The extensive use of plastic mulch film is a major contributor to microplastic pollution in this catchment. The differences and connections observed in microplastics imply mutual migration and deposition within the catchment. A check dam at the outlet effectively intercepts microplastics during the rainstorm, reducing the microplastic by at least 6.1 × 1010 items downstream. This study provides a reference for the effects of rainstorms on the sources and pathways of MP pollution in regions prone to severe soil erosion.

Occurrence and distribution of microplastics in surface sediments of a typical river with a highly eroded catchment, a case of the Yan River, a tributary of the Yellow River

Investigation of microplastic contamination in riverbed sediments can help clarify long-term microplastic pollution and establish prevention measures in watersheds. However, little research has been conducted on riverbed sediment pollution on the Loess Plateau, a highly eroded area in Northwest China. This research investigates the Yan River as a case study. The occurrence and distribution of microplastics were surveyed and analyzed to explore the microplastic pollution in the riverbed of the Loess Plateau. Microplastics were found in all sediment samples, with an abundance of 208.89-686.67 items kg^-1. Polypropylene and polyethylene were the main microplastic components identified using Fourier transform infrared spectrometry and imaging systems. Particles 0.5-1.0 mm in size accounted for 38.5 % of the total microplastics in this region. The main microplastic colors were black, white, and transparent, which accounted for 40.75 %, 20.75 %, and 20.38 % of the total microplastics, respectively. There was an increasing trend in the microplastic abundance in sediments in the downstream direction that accompanied the increase in population density from 55.31 persons km^-2 upstream to 230.05 persons km^-2 downstream. Microplastic pollution was related to the complex geographical, semiarid monsoon climate, elevation, grassland, per capita GDP, and anthropogenic factors in the Yan River basin. The erodible loess and high-intensity rainstorm promoted severe soil erosion, which caused microplastics absorbed in the soil to migrate to the river. Poorly managed solid wastes, such as agricultural mulch, plastic bottles, and other plastic products are also sources of microplastics in the riverbed. This study further clarifies microplastic pollution in typical rivers of highly erosive areas and provides useful information for basin management.

Microplastics in plateau agricultural areas: Spatial changes reveal their source and distribution characteristics

The Huangshui catchment on the northeastern Qinghai-Tibet Plateau (QTP) was selected as the study area to investigate the abundance, distribution characteristics, and influencing factors of microplastics (MPs) in surface agricultural soils (0-20 cm). The MP levels ranged from 6 to 444 items/kg, with an average of 86 items/kg. The relative abundance of small-sized MPs (<2 mm) was higher than that of large-sized MPs (2-5 mm). Polyethylene was the most common, and residual mulching film in farmland was the main source of MPs. The spatial distribution characteristics of MPs were analyzed through inverse distance weight interpolation, and MP abundance in agricultural soils in neighboring urban areas was significantly higher than that in other areas. Further analysis found that population density was significantly positively correlated with MP abundance (R² = 0.9090, p < 0.01), indicating that human activities play a key role in MP pollution even in remote areas. In addition, the effects of irrigation, land use type, and soil physicochemical properties on the abundance of MPs were analyzed. Atmospheric transport and irrigation with surface water contribute to soil MP pollution. The direct effects of soil properties on MP abundance are still largely unclear, requiring further studies.

Microplastic in the Baltic Sea: A review of distribution processes, sources, analysis methods and regulatory policies

Microplastics pollution is an issue of great concern for scientists, governmental bodies, ecological organisations, and the general public. Microplastics pollution is widespread and is a great environmental problem on account of its potential toxicity for marine biota and human health. Today, almost all the world's seas and oceans are polluted with microplastics. The Baltic Sea is a semi-enclosed reservoir of brackish water and is a hotspot for contamination in terms of eutrophication and the presence of organic matter. Microplastics are quite intense, based on data from studies of marine litter and microplastics in the Baltic Sea. The number of microplastics in the Baltic Sea water is 0.07-3300 particles/m³, and in sediments 0-10179 particles/kg. These amounts prove that the waters and sediments of the Baltic Sea are heavily contaminated with microplastics. This article provides a comprehensive review of the microplastic origins and transport routes to the Baltic Sea. The data is presented as the concentration of microplastics in surface waters, sediments, and sea sand. The extraction methods used and the microplastics techniques are also presented. The possibilities and limitations of water and sediment sampling methods for microplastics determination were summarised, taking into account sampling tools, volume and depth. Extraction, separation, filtration, and visual sorting are outlined as sample preparation techniques for microplastic analysis. This review also focuses on the problems of obtaining data relevant to the development of the mathematical models necessary to monitor trends in the spread of microplastics in the Baltic Sea. Finally, several important laws and policies, which are in place in the Baltic States to control and manage microplastic pollution in the region, are highlighted.