Microplastics distribution in bottom sediments of the Baltic Sea Proper

Baseline assessment of metal and microplastic pollution in sediments of a small-sized harbor in western Baltic Sea (Kalmar, Sweden)

This study provides a baseline analysis of sediment pollution in Kalmar Guest Harbor, Sweden, focusing on metals and microplastics. The study site, a bustling coastal area, was chosen to investigate the connections between anthropogenic activities, bioturbation, and environmental contaminants. The results revealed that the pollution extends beyond 30 cm of depth below the seafloor, with elevated levels of copper (Cu), tungsten (W), cadmium (Cd), zinc (Zn), lead (Pb), and microplastics. Significantly, there is no previous publication alarming the W contamination in the Baltic Sea sediment, and therefore, our findings highlight the need for further investigation into tungsten contamination in the region. Furthermore, we explored the distribution patterns, potential sources and relationships of different contaminants. The K-means cluster analysis revealed that bioturbation is speculated to influences the depth concentration of pollutants, particularly at shallow depths (0‬-18 cm). Metal contaminants do not appear to be predominantly bound to MP particles.

Microplastics in seawater and fish acquired from the corresponding fishing zones of the Baltic Sea

Microplastics in seawater and fish from the Baltic Sea were analyzed. The significant contribution of the study is due to extensive collection of fish and surface water samples from corresponding fishing zones. Microplastics were detected in 100 % of seawater and 61 % of fish samples. The abundances of microplastics were 19,984 ± 8858 items/m3 (seawater) and 3.3 items/fish in the fish organs. The average dimension was 1.08 ± 1.19 mm (seawater), and 0.77 ± 0.84 mm (fish). In 106 out of 178 specimens (61 %), MPs were found in the gills (46 %), digestive tract (38 %), or liver (16 %). Fiber was the most dominant shape found in seawater (91.7 %) and fish (68.3 %), while the dominant color of items was blue. Items were mostly composed of polyethylene (21 %), polypropylene (20 %), cellophane (16 %), polyamide (9 %), and polyacrylate (8 %).

Microplastics in aquatic systems: A comprehensive review of its distribution, environmental interactions, and health risks

Microplastics (MPs) have become a critical pollutant, accumulating in aquatic ecosystems and posing significant environmental and human health risks. Approximately 5.25 trillion plastic particles float in global oceans, releasing up to 23,600 metric tonnes of dissolved organic carbon annually, which disrupts microbial dynamics. MPs arise from the breakdown of larger plastics, degraded by photodegradation, thermal degradation, and biological processes, which are influenced by polymer type and environmental factors. As carriers, MPs absorb and transport contaminants such as heavy metals, per- and polyfluoroalkyl substances (PFAS), and persistent organic pollutants (POPs) across trophic levels, thereby increasing toxicity within food webs. Key aquatic organisms, including microalgae, molluscs, and fish, experience cellular toxicity, oxidative stress, and disruptions in essential functions due to MP ingestion or adhesion, raising concerns about their bioaccumulation in humans through ingestion, inhalation, and dermal contact. The complex surface chemistry of MPs enhances their pollutant adsorption, a process modulated by environmental pH, salinity, and contamination levels, while aging and structural attributes further impact their bioavailability and toxicity. This review consolidates knowledge on MPs' occurrence, transformation, pollutant interactions, and methodologies for sampling and analysis, emphasizing advancements in spectroscopy and imaging techniques to improve MP detection in aquatic environments. These insights underscore the pressing need for standardized analytical protocols and comprehensive toxicological research to fully understand MPs' effects on ecosystems and human health, informing future mitigation strategies and policy development.

Estimation of bottom microplastic flux in the Indonesian seas

Marine debris, particularly microplastics, is an important environmental problem for Indonesia, impacting vast coastline and diverse marine ecosystems. However, little is known about the microplastics flux to the seafloor in the Indonesian Seas. This study employs HYCOM data and Lagrangian particle tracking model to analyze the distribution of microplastics flux to the seafloor from 68 rivers in Indonesia. Microplastics accumulation can be found in coastal waters near major islands, typically within 50-100 km of the coast. Accumulation regions within the Fisheries Management Area (FMA) in Indonesia are mostly located in Karimata Strait, Java Sea and South Java. This study highlights the importance of understanding sinking particles behavior for effective waste management strategies, as well as for mitigating environmental impacts in Indonesian waters.

High microplastic pollution in marine sediments associated with urbanised areas along the SW Bulgarian Black Sea coast

This study aims to provide baseline data on microplastic (MP) concentrations in beach and seabed sediments of the SW Black Sea coast, and to identify possible sources of MP pollution in the area. MP concentrations in beach sediments in urbanised coastal areas, as well as in all seabed sediments, were on average higher than in other parts of the Black Sea and most other European seas. Urban coastal areas showed the highest average MP concentrations (mean ± SD): 464.44 ± 272.50 MP·kg-1 dry sediment in beach samples, 825.93 ± 396.30 MP·kg-1 dry sediment in seabed samples, while coastal sediments in an area with no local anthropogenic activities had significantly lower average MP concentrations: 84.44 ± 147.57 MP·kg-1 in beach samples, and 550.62 ± 245.71 MP·kg-1 in seabed samples. Possible identified sources of MPs include sewage water discharges, urban waste, coastal fisheries and aquaculture, as well as accumulation of marine litter on beaches and in adjacent offshore areas, serving as sources of secondary MP pollution.

Fibrous microplastics in the environment: Sources, occurrence, impacts, and mitigation strategies

Fibrous microplastics (FMPs), a unique class of microplastics, are increasingly recognized as a significant environmental threat due to their ubiquitous presence and potential risks to ecological and human health. This review provides a comprehensive overview of FMPs, including their sources, prevalence in various environmental media, and potential impacts. FMPs, which can be found in over 90 % of certain environmental samples, originate from a diverse range of sources, including synthetic textiles, landfill waste, industrial emissions, and atmospheric deposition. These persistent pollutants pose a threat to both terrestrial and marine ecosystems. Their insidious presence can lead to ingestion by organisms, potentially disrupting ecosystems and posing risks to human health. Addressing the challenge of FMPs requires a multi-faceted approach. Reducing the production and use of synthetic fibers, implementing effective waste management practices, and developing new technologies to remove FMPs from wastewater and the broader environment are all crucial components of the solution. However, further research is essential to fully understand the long-term implications of FMPs on ecosystems and human health, laying the foundation for the development of robust and effective mitigation strategies.

Microplastics in ecosystems: Critical review of occurrence, distribution, toxicity, fate, transport, and advances in experimental and computational studies in surface and subsurface water

Microplastics (MPs), particles under 5 mm, pervade water, soil, sediment, and air due to increased plastic production and improper disposal, posing global environmental and health risks. Examining their distribution, quantities, fate, and transport is crucial for effective management. Several studies have explored MPs' sources, distribution, transport, and biological impacts, primarily focusing on the marine environment. However, there is a need for a comprehensive review of all environmental systems together for enhanced pollution control. This review critically examines the occurrence, distribution, fate, and transport of MPs in the following environments: freshwater, marine, and terrestrial ecosystems. The concentration of MPs is highly variable in the environment, ranging from negligible to significant amounts (0.003-519.223 items/liter in water and 0-18,000 items/kg dry weight sediment, respectively). Predominantly, these MPs manifest as fibers and fragments, with primary polymer types including polypropylene, polystyrene, polyethylene, and polyethylene terephthalate. A complex interplay of natural and anthropogenic actions, including wastewater treatment plant discharges, precipitation, stormwater runoff, inadequate plastic waste management, and biosolid applications, influences MPs' presence and distribution. Our critical synthesis of existing literature underscores the significance of factors such as wind, water flow rates, settling velocities, wave characteristics, plastic morphology, density, and size in determining MPs' transport dynamics in surface and subsurface waters. Furthermore, this review identifies research gaps, both in experimental and simulation, and outlines pivotal avenues for future exploration in the realm of MPs.

Occurrence and distribution of microplastics in the adjacent environment of Yellow River Delta, China

In the precent study, the microplastics (MPs) pollution level was evaluated in diverse environmental samples from the Yellow River Delta. The results indicated that the abundance of MPs in water, sediment and soil samples ranged from 0.50 to 7.83 items·L-1, 200 to 4200 items·kg-1, and 100 to 1400 items·kg-1, respectively. Film form of MPs was dominant in water, while fiber MPs were dominant in both sediment and soil samples. In all samples, most MPs were < 1 mm in size. White was the main color in water, black was the main color in sediment and soil samples. The most common MPs type was polyethylene (33 %) in water, while rayon accounted for the majority of MPs in sediment (42 %) and soil (70 %) samples. The redundancy analysis results showed that MPs in water and sediment were more affected by water quality, while soil MPs were easily affected by landscape pattern.

Spatio-temporal distribution of microplastic pollution in surface sediments along the coastal areas of Istanbul, Turkey

Microplastics (MPs) have become prevalent in various environmental compartments, including air, water, and soil, attracting attention as significant pollutant parameters. This study investigated the prevalence of MP pollution in surface sediments along Istanbul's Marmara Sea, encompassing the megacity and the Bosphorus. A comprehensive sampling approach was employed, covering 43 stations across four seasons and depths ranging from 5 to 70 m. The objective was to assess the impact of terrestrial, social, and industrial activities on MPs. The average concentrations varied per season, with fall, winter, spring, and summer values recorded as 2000 ± 4100, 1600 ± 3900, 4300 ± 12,000, and 9500 ± 20,300 particles/kg-DW. The study identified river stations in the Golden Horn and sea discharge locations as hotspots for high concentrations. Notably, the dominant shape shifted from fibers in fall, winter, and spring to fragments during summer, coinciding with mucilage occurrences. The study identified 11 different polymers, with polyethylene (44 %) and polypropylene (31 %) being the most common.

The pollution of microplastics in sediments: The ecological risk assessment and pollution source analysis

The occurrence of microplastics (MPs) pollution in sediments has brought huge challenges to the development of society. Pollution control of MPs in sediments has become an inevitable requirement for current society. This requires implementing targeted pollution control measures in high MPs ecological risk areas and controls MPs discharge in pollution source. Existing studies lack in-depth understanding in MPs ecological risk assessment and MPs pollution source analysis, this limits the pollution control of MPs in sediments. In this study, the studies of MPs pollution in sediments from 2013 to 2022 were reviewed. The results showed that the environmental problems caused by MPs pollution in marine sediments have been widely discussed over the past decade. And the occurrence of MPs pollution in sediments brought potential threat to marine ecology and human food supply. Furthermore, pollution load index, polymer risk index and potential ecological risk index of MPs were frequently used in the existing ecological risk assessment of MPs in sediments. A large amount of monitoring data and simulation data is conducive to improving these MPs ecological risk assessment indicators. This can provide a useful reference for managers to formulate MPs pollution control measures. And MPs types and land-use types can provide basis to analyze the pollution source of MPs in sediments. Developing more accurate MPs detection and analysis technologies can further improve current MPs pollution source analysis system. This is conducive to control the discharge of MPs in the pollution source. In future studies, more complete MPs ecological risk assessment system and MPs pollution source analysis system should be established to control the pollution of MPs in sediments.

The role of seagrass meadows in the accumulation of microplastics: Insights from a South African estuary

Microplastics are widespread in marine ecosystems, where they threaten biota and human wellbeing. Seagrasses may act as natural filters of microplastics due to their particle trapping abilities, yet little is known about the extent of microplastics in the sediment of seagrass beds. The aim of this study was to compare microplastic accumulation in the sediments of Zostera capensis meadows with adjacent bare sediments at a small spatial scale (~5 km) in the Knysna estuary in South Africa. No significant difference in total microplastic counts were found between seagrass and unvegetated sediments. However, fibre microplastic counts differed significantly between the two locations at which samples were collected. This may be due to pollution levels and proximity to larger human population densities. Importantly, our study reveals variability in microplastic abundance and type even at small spatial scales, an important consideration for the design of future studies aiming to monitor for microplastics.

Transport and accumulation of plastic particles on the varying sediment bed cover: Open-channel flow experiment

Contamination of sea bottom sediments by microplastics is widely confirmed, but the reasons for its patchiness remain poorly understood. Laboratory experiments are reported where combined sets of various plastic particles, different by shape, size, density, and flexibility, were transported by the step-wise increasing open-channel flow over the bottom covered with natural sediment of increasing grain size. For every particular flow velocity, observations revealed the recurrent formation of relatively narrow retention areas, where plastic particles lingered for some time in their motion. These areas follow the line of change of the sediment type from finer to coarser grains. It is shown that contact friction drives the retention of a particle at finer sediments, while particle/sediment-grain interaction becomes of importance when particles and sediment grains are of similar sizes. The presence of this effect can be expected for a relatively wide range of natural conditions.