High Concentrations Of Microplastics Research Articles

Metabolic responses of the marine mussel Mytilus galloprovincialis after exposure to microplastics of different shapes and sizes

Microplastics (MP) are ubiquitous pollutants with diverse shapes, sizes, and characteristics that pose critical risks to marine organisms and the environment. In this study, we used the Mediterranean mussel Mytilus galloprovincialis as a marine benthic organism model to investigate the metabolic consequences of exposure to different polyethylene terephthalate MP sizes and shapes: round (27–32 μm), small fibers (200–400 μm), large fibers (3000 μm), small fragments (20 μm), medium fragments (45–75 μm), and large fragments (>150 μm). After exposure to high concentrations (100 mg L−1) of MP for 14 days, round and small fiber-type MP were highly accumulated in mussels. Metabolomic analysis revealed that exposure to round and small fiber-type MP induced significant changes in 150 metabolites. Partial least squares-discriminate analysis (PLS-DA) showed that the round and small fiber MP treatment groups displayed similar cluster patterns that differed from those of the control group. In addition, only 22 annotated metabolites related to histidine, valine, leucine, and isoleucine degradation/biosynthesis and vitamin B6 and aminoacyl-tRNA biosynthesis were significantly affected by round or small fiber-type MP. Among the histidine metabolites, round and small fiber-type MP upregulated the levels of L-histidine, L-glutamate, carnosine, imidazole-4-acetaldehyde, 4-imidazolone-5-propanoate, and methylimidazole acetaldehyde and downregulated methylimidazole acetic acid and N-formimino-L-glutamate. These results suggest novel insights into the potential pathways through which MP of specific sizes and shapes affect metabolic processes in mussels.

Effect of different microplastics on the mobilization of soil inorganic phosphorus by exomycorrhizal fungi

<p>Microplastics (MPs) can affect the phosphorus (P) cycle in soil by changing soil properties and the function of microbial communities, but their impact on soil P availability remains unclear. To explore the effects of different types of MPs on the mobilization of soil inorganic P by exomycorrhizal fungi, Lactarius delicious (Ld) was used as the test strain, and polystyrene microspheres (PS), polypropylene (PP) and poly(lactic acid) (PLA) were used as test materials. The soil was used as the only P source for the media. The effect of different types of MPs on the mobilization of soil inorganic P by exomycorrhizal fungi was studied using liquid culture method. The results showed that exposure to MPs at low to medium concentrations (10 or 100 mg L-1) activated inorganic P in soil by stimulating the secretion of additional organic acids and hydrogen ions by ectomycorrhizal fungi, improving the available P in soil. The effect of mobilizing inorganic P was more significant in the treatment groups exposed to low and medium concentrations of biodegradable PLA. This may be related to the fact that PLA stimulated the ectomycorrhizal fungi to secrete more organic acids, and the release of a large amount of lactic acid after PLA was biodegraded. However, when the exposure concentration of MPs further increased, the growth of ectomycorrhizal fungal mycelium may be inhibited, the secretion of organic acids and hydrogen ions may be reduced, and the mobilization ability of soil inorganic P may be limited. In addition, it should be noted that high concentrations of non biodegradable MPs (PS and PP) had significant limiting effects on the mobilization of soil inorganic P by exomycorrhizal fungi. Therefore, our study results provide evidence that the presence of MPs may reduce the availability of soil P. Further research should focus on maintaining or improving P availability in plant-microbe systems in MP-polluted soil.</p>

First Evidence of the Effects of Polyethylene Terephthalate Microplastics on Ruminal Degradability and Gastro-Intestinal Digestibility of Mixed Hay

Microplastics (MPs) raise environmental concerns. However, their effects on the ruminal–gastro-intestinal system have not yet been studied. This study aims to investigate the effects of polyethylene terephthalate (PET) MPs on the ability of the ruminal–gastro-intestinal system to degrade and digest mixed hay. Using a three-step in vitro ruminal–gastro-intestinal incubation system, PET MPs were introduced at concentrations of 0, 5, 10, and 15 g/L in ruminal and gastro-intestinal solutions. Ruminal fluid was collected from three 16-month-old Piedmontese bulls. The experiment was conducted on three mixed hays and was repeated three times, with triplicate incubations in each run. The results reveal that PET MPs reduced the degradability and digestibility of crude protein. Specifically, crude protein degradation was reduced by 9% at medium and 16% at high PET MP concentrations in the ruminal phase, while the crude protein digestibility of undegraded crude protein was reduced by 8% at the lowest PET MPs concentration in the gastro-intestinal tract. Additionally, PET MPs reduced the degradation of neutral detergent fiber at medium and high PET MP concentrations in the ruminal phase by 9% and 13%, respectively. These results highlight the risks of PET MPs contamination on ruminal–gastro-intestinal functions and underscore the urgent need to mitigate MPs contamination in the livestock sector.

Release kinetic study of microplastics from N95 face masks and consequent effects on freshwater alga Scenedesmus obliquus

The uncontrolled disposal of N95 face masks, widely used during the recent COVID-19 pandemic can release significant amounts of microplastics and other additives into aquatic bodies. This study aimed to: (i) to quantify and analyze the released microplastics and heavy metals from N95 face masks weathered for various time periods (24, 48, 72, 96, 120, and 144 h) and (ii) to assess the cytotoxicity potential of the leachates on a model organism, freshwater alga Scenedesmus obliquus. The mask leachates contained microplastics, polypropylene in different shapes and sizes, and heavy metals like Cu, Cd, and Zn. The leachates significantly reduced cell viability and increased reactive oxygen species (ROS) generation, antioxidant enzyme activity, and membrane damage. The effects were also accompanied by a significant drop in the photosynthetic yield. All of the examined parameters indicated a dose-response relationship, with longer leaching periods resulting in higher microplastic concentrations. Mask leachates severely damaged the structural integrity of the algal cells, as seen in scanning electron microscopy images. The findings of our study confirm that the releases from disposable N95 face masks pose a severe threat to freshwater microalgae, and the cascading effects would harm the aquatic ecosystems.

MPs and PFOS single and combined exposure significantly alter genetic expressions of growth hormone and insulin growth factor-related biomarkers during zebrafish embryonic development

Microplastics (MPs) and perfluorooctane sulfonate (PFOS) are emerging pollutants that are ubiquitously present in the environment and can cause series of ecotoxicological effects on aquatic animals. This study examined how the expression of genes related to insulin growth factor (igf1, igf2a, igf2b, igfra, and igfrb) and growth hormone (ghrh, gh1, ghra, and ghrb) changes during the development of zebrafish embryos exposed to 8 μm polyethylene microplastics (PE-MPs) and perfluorooctane sulfonate (PFOS) individually and in combination for 72 h. Our findings revealed that both low-concentrations of MP (50 μg/L) and PFOS (0.02 μg/L) treatments could significantly activate gene expression within a short period. High concentrations of MPs (500 μg/L) and PFOS (0.1 μg/L) not only rapidly activated gene expression but also sustained high expression levels for a longer duration. During combined exposures, peak gene expression in the low concentration groups (50 μg/L MPs and 0.02 μg/L PFOS; 50 μg/L MPs and 0.1 μg/L PFOS) primarily occurred within 12 h after treatment. In the high concentration groups (500 μg/L MPs and 0.02 μg/L PFOS), peak expression was also observed within 12 h. Notably, the combined exposure groups exhibited more pronounced effects on gene expression than the individual exposure groups. The activation of gene expression was both more significant and longer-lasting in the combined exposure, indicating a synergistic regulatory effect of MPs and PFOS. Overall, our study suggests that zebrafish embryo development can be significantly impacted by exposure to MPs, PFOS, and their combination, with combined exposures having a more lasting and profound effect on gene regulation compared to single exposures.

Microplastics and their interaction with microorganisms in Bosten Lake sediment

Microplastics (MPs), discovered in oceans, lakes, and rivers, can infiltrate the food chain through ingestion by organisms, potentially posing health risks. Our research is the first to study the composition and distribution of MPs in Bosten Lake's sediment. In May, the average abundance of MPs was 0.95±0.72 particles per 10 grams, and in October, it was 0.90±0.61 particles per 10 grams. Bohu Town had the highest MP abundance, with 1.75±0.35 particles per 10 grams in spring and 2±0 particles per 10 grams in autumn. In May, 53% of the MPs were transparent, while in October, black MPs constituted 58%. The predominant morphology was fibrous, accounting for 61% of the total. MPs in the size range of 0.2-1 mm made up 91% and 66% of the total in May and October, respectively. The most common types of MPs in May were polyethylene terephthalate (PET) at 40% and polyethylene (PE) at 26%. In October, PET was the most prevalent at 71%, followed by poly(ether-ether-ketone)(PEEK) at 11%. Certain microbial taxa, such as Actinobacteriota, Pseudomonas, and Vicinamibacteraceae, associated with MP degradation or complex carbon chain breakdown, were notably enriched in sediment areas with high MP concentrations. A significant positive correlation was observed between the abundance of MPs in sediments and Actinobacteriota. Additionally, the abundance of Thiobacillus, Ca.competibacter, and other bacteria involved in soil element cycling showed a significant positive correlation with the organic matter content in the sediments. Anaerobic bacteria like Thermoanaerobacterium displayed a significant positive correlation with water depth. Our study reveals the presence, composition, and distribution of MPs in Bosten Lake's sediments, shedding light on their potential ecological impact.

Microplastic accumulation and oxidative stress in sweet pepper (Capsicum annuum Linn.): Role of the size effect

Microplastics (MPs), which are widely dispersed in terrestrial environments, threaten crop growth and human food security. However, plant accumulation and phytotoxicity related to the size effects of MPs remain insufficiently explored. This study investigated the accumulation and toxicity of two sizes of MPs on Capsicum annuum Linn. (C. annuum) through fluorescence tracing and antioxidant defense system assessment. The results revealed that the size of MPs significantly impacts their accumulation characteristics in C. annuum roots, leading to variations in toxic mechanisms, including oxidative stress and damage. Smaller MPs and higher exposure concentrations result in more pronounced growth inhibition. C. annuum roots have a critical size threshold for the absorption of MPs of approximately 1.2 μm. MPs that enter the root tissue exhibit an aggregated form, with smaller-sized MPs displaying a greater degree of aggregation. MP exposure induces oxidative stress in root tissues, with high concentrations of smaller MPs causing lipid peroxidation. Analysis of the IBR values revealed that C. annuum roots utilize ascorbic acid (ASA) to prevent oxidative damage caused by larger MPs. Conversely, smaller MPs primarily induce superoxide dismutase (SOD) and glutathione (GSH). These results emphasize the significant impact of MP size on plant antioxidant defense response mechanisms, laying the foundation for further investigating the implications for human health.

Microplastic concentration, characterization, and size distribution in the Delaware Bay estuary

Microplastic (MP) pollution has been widely reported across water matrices including in estuaries, which are important for the understanding of oceanic MPs. Estuaries can greatly alter the fate, transport, size distribution, and abundance of plastic pollution. The aim of this study was to quantify and characterize MP pollution in the Delaware Bay estuary USA, including the size distribution. Samples (N = 31) were collected from the mouth of the Delaware River to the coastal ocean including multiple frontal zones across two sampling campaigns (2019 and 2022). MP were extracted from the collected particles using wet peroxide oxidation and density separation with saturated sodium chloride. Particles collected on 500 μm mesh sieves were analyzed via Fourier transform infrared (FTIR) spectroscopy. Across all samples, 324 of the 1015 particles analyzed were MP, and 11 macroplastics were observed. MP concentrations ranged from below detection to 4.12 MP/m3 (mean 0.34 ± 0.80 MP/m3). No significant differences were observed between sampling sites; nonetheless, the two highest MP concentrations were observed when sampling along frontal zones with visible debris including macroplastics. Polyethylene (53%) and polypropylene (43%) were the most abundant polymers observed. The majority of the non-plastic particles were classified as particulate natural organic matter (82% of non-plastics). Particles from samples collected during 2022 (N = 864) also had color, morphology, and two size dimensions recorded. MP particle size was significantly associated with sampling site, with the coastal ocean sampling site generally having the smallest MPs. A correlation between total post-extraction particles and total plastic particles was observed. Aspect ratios for the plastics ranged from one to 40.7, with larger ratios for fibers, with a mean (±standard deviation) of 3.39 ± 4.72 (unitless). These aspect ratios can be used to select shape factors used to estimate the total volume of MP in the studied size range. Overall, these results can help inform fate, transport, and risk assessments related to estuarine plastic pollution.

The impacts of biodegradable and non-biodegradable microplastic on the performance and microbial community characterization of aerobic granular sludge.

Microplastics (MPs), identified as emerging contaminants, have been detected across diverse environmental media. Their enduring presence and small size facilitate the adsorption of organic pollutants and heavy metals, leading to combined pollution effects. MPs also accumulate in the food chain thus pose risks to animals, plants, and human health, garnering significant scholarly attention in recent years. Aerobic granular sludge (AGS) technology emerges as an innovative approach to wastewater treatment. However, the impacts of MPs on the operational efficiency and microbial characteristics of AGS systems has been insufficiently explored. This study investigated the effects of varying concentration (10, 50, and 100 mg/L) of biodegradable MPs (Polylactic Acid, PLA) and non-biodegradable MPs (Polyethylene Terephthalate, PET) on the properties of AGS and explored the underlying mechanisms. It was discovered that low and medium concentration of MPs (10 and 50 mg/L) showed no significant effects on COD removal by AGS, but high concentration (100 mg/L) of MPs markedly diminished the ability to remove COD of AGS, by blocking most of the nutrient transport channels of AGS. However, both PLA and PE promoted the nitrogen and phosphorus removal ability of AGS, and significantly increased the removal efficiency of total inorganic nitrogen (TIN) and total phosphorus (TP) at stages II and III (P < 0.05). High concentration of MPs inhibited the growth of sludge. PET noticeably deteriorate the sedimentation performance of AGS, while 50 mg/L PLA proved to be beneficial to sludge sedimentation at stage II. The addition of MPs promoted the abundance of Candidatus_Competibacter and Acinetobacter in AGS, thereby promoting the phosphorus removal capacity of AGS. Both 50 mg/L PET and 100 mg/L PLA caused large amount of white Thiothrix filamentous bacteria forming on the surface of AGS, leading to deterioration of the sludge settling performance and affecting the normal operation of the reactor. Comparing with PET, AGS proved to be more resistant to PLA, so more attention should be paid to the effect of non-biodegradable MPs on AGS in the future.

Mangrove mud clam as an effective sentinel species for monitoring changes in coastal microplastic pollution

The worldwide mangrove shorelines are experiencing considerable contamination from microplastics (MPs). Finding an effective sentinel species in the mangrove ecosystem is crucial for early warning of ecological and human health risks posed by coastal microplastic pollution. This study collected 186 specimens of the widely distributed mangrove clam (Geloina expansa, Solander, 1786) from 18 stations along the Leizhou Peninsula, the largest mangrove coast in Southern China. This study discovered that mangrove mud clams accumulated a relatively high abundance of MPs (2.96 [1.61 – 6.03] items·g-1) in their soft tissue, wet weight, as compared to previously reported levels in bivalves. MPs abundance is significantly (p < 0.05 or 0.0001) influenced by coastal urban development, aquaculture, and shell size. Furthermore, the aggregated MPs exhibit a significantly high polymer risk index (Level III, H = 353.83). The estimated annual intake risk (EAI) from resident consumption, as calculated via a specific questionnaire survey, was at a moderate level (990 – 2475, items·g -1·Capita -1). However, the EAI based on suggested nutritional standards is very high, reaching 113,990 (79,298 − 148,681), items·g -1·Capita -1. We recommend utilizing the mangrove mud clam as sentinel species for the monitoring of MPs pollution changing across global coastlines.

Assessment of Microplastic Pollution in River Ecosystems: Effect of Land Use and Biotic Indices

The proximity of freshwater ecosystems to anthropogenic activities makes them one of the most threatened environments by plastic pollution in the form of microplastics (MPs). Therefore, it is crucial to identify the primary drivers of MP dynamics in rivers to enhance their management. This work analyzed the concentration of MPs in water and sediments and evaluated the influence of land use and its relationship with the main biotic indices employed to assess the water quality of rivers. This research was carried out in four different catchments, with three sampling points established in each river basin. The results revealed that MPs were ubiquitous across all locations, with concentrations ranging from 0.10 to 35.22 items m−3 in waters and from 26 to 643 items Kg−1 in sediments. The highest concentration of MPs both in water and sediments were found in the Lagares River (35.22 items m−3 and 643 items Kg−1), while the lowest concentrations were found in the Miñor River for water (0.10 items m−3) and Tea River for sediments (138 items Kg−1). Urbanization degree was identified as the primary driver of MP pollution in water, whereas population density correlated with sediment pollution levels. These findings explain the elevated MPs abundance in the more urbanized and populated Gafos and Lagares rivers compared to the relatively pristine Miñor and Tea rivers. Furthermore, the presence of MPs in sediments was found to negatively impact the most sensitive benthic macroinvertebrate taxa, as evidenced by lower values of the IASPT and EPT indices at sampling points with higher sediment MPs concentrations (Gafos and Lagares).

Effects of micro- and nano-plastics on growth, antioxidant system, DMS, and DMSP production in Emiliania huxleyi

Due to the potential impacts of microplastics (MPs) and nanoplastics (NPs) on algal growth and thereby affect the climate-relevant substances, dimethylsulfoniopropionate (DMSP) and dimethyl sulfide (DMS), we studied the polystyrene (PS) MPs and NPs of 1 μm and 80 nm impacts on the growth, chlorophyll content, reactive oxygen species (ROS), antioxidant enzyme activity, and DMS/DMSP production in Emiliania huxleyi. E. huxleyi is a prominent oceanic alga that plays a key role in DMS and DMSP production. The results revealed that high concentrations of MPs and NPs inhibited the growth, carotenoid (Car), and Chl a concentrations of E. huxleyi. However, short-time exposure to low concentrations of PS MPs and NPs stimulated the growth of E. huxleyi. Furthermore, high concentrations of MPs and NPs resulted in an increase in the superoxide anion radical (O2.–) production rate and a decrease in the malondialdehyde (MDA) content compared with the low concentrations. Exposure to MPs and NPs at 5 mg L−1 induced superoxide dismutase (SOD) activity as a response to scavenging ROS. High concentrations of MPs and NPs significantly inhibited the production of DMSP and DMS. The findings of this study support the potential ecotoxicological impacts of MPs and NPs on algal growth, antioxidant system, and dimethylated sulfur compounds production, which maybe potentially impact the global climate.

Warming temperatures exacerbate effects of microplastics in a widespread zooplankton species.

The emergence of microplastics as a global contaminant of concern has coincided with climate change induced temperature warming in aquatic ecosystems. Warmer temperatures have been previously demonstrated to increase the toxicity of certain contaminants, but it is currently unclear if microplastics are similarly affected by temperature. As aquatic organisms simultaneously face microplastic pollution and both increasing and variable temperatures, understanding how temperature affects microplastic toxicity is pertinent in this era of human-induced global change. In this study, we investigate the effects of environmentally relevant microplastic exposure to Daphnia pulex survival, reproduction, and growth at three different temperatures. To simulate an environmentally relevant exposure scenario, we created microplastics with physicochemical characteristics often detected in nature, and exposed organisms to concentrations close to values reported in inland waters and 1-2 orders of magnitude higher. The three temperatures tested in this experiment included 12 °C, 20 °C, and 24 °C, to simulate cool/springtime, current, and warming scenarios. We found the highest concentration of microplastics significantly impacted survival and total offspring compared to the control at 20 °C and 24 °C, but not at 12 °C. The adverse effect of high microplastic concentrations on total offspring at warmer temperatures was driven by the high mortality of the juveniles. We observed no effect of microplastics on time to first reproduction or average growth rate at any temperature. Warmer temperatures exacerbated microplastic toxicity, although only for concentrations of microplastics not currently observed in nature, but these concentrations are possible in pollution hotspots, through pulses pollution events or future worsening environmental contamination. The results of our study illustrate the continued need to further investigate climate change related co-stressors such as warming temperatures in microplastic and pollution ecology, through environmentally realistic exposure scenarios.

Unveiling high concentrations of small microplastics (11–500 μm) in surface water samples from the southern Weddell Sea off Antarctica

Recent studies have highlighted the prevalence of microplastic (MP) pollution in the global marine environment and these pollutants have been found to contaminate even remote regions, including the Southern Ocean south of the polar front. Previous studies in this region have mostly focused on MPs larger than 300 μm, potentially underestimating the extent of MP pollution. This study is the first to investigate MPs in marine surface waters south of the polar front, with a focus on small MPs 500–11 μm in size. Seventeen surface water samples were collected in the southern Weddell Sea using an in-house-designed sampling system. The analysis of the entire sample using micro-Fourier transform infrared spectroscopy (μFTIR) with focal plane array (FPA) detection revealed the presence of MPs in all samples, with the vast majority of the MPs detected being smaller than 300 μm (98.3 %). The mean concentration reached 43.5 (± 83.8) MPs m−3, with a wide range from 0.5 to 267.2 MPs m−3. The samples with the highest concentrations differed from the other samples in that they were collected north of the continental slope and the Antarctic Slope Current. Sea ice conditions possibly also influenced these varying concentrations. This study reports high concentrations of MPs compared to other studies in the region. It emphasizes the need to analyze small MPs, down to a size of 11 μm or even smaller, in the Antarctic Treaty Area to gain a more comprehensive understanding of MP pollution and its potential ecological impacts.

Growth and physiological responses of Myriophyllum sp. “Roraima” growing in co-cultivation with Microcystis aeruginosa under the influence of microplastics

The distribution of microplastics as a potential environmental risk in aquatic systems had gained increasing attention in recent years. While numerous studies had focused on the impacts of microplastics on aquatic plants, the impacts on plant species cannot been considered in isolation. This study investigated the effects of relatively low concentrations of microplastics (0 mg/L, 0.05 mg/L, 0.25 mg/L, 1.25 mg/L, and 6 mg/L) on Myriophyllum sp. “Roraima” in co-cultivation with Microcystis aeruginosa (M. aeruginosa). Microscopic observations confirmed the adsorption of microplastic particles to the roots of Myriophyllum sp. “Roraima”. The presence of cyanobacteria could mask and moderate the effects of microplastics, creating an integrated impact on plants. This integrated impact potentially made it challenging to isolate and attribute specific effects solely to microplastics. Additionally, the co-cultivation with M. aeruginosa had its own effect on the plants. Results revealed that the plant shoot elongation was not significantly altered under the treatment conditions; however, the photosynthetic pigments demonstrated different patterns between the emergent and submerged sections. The activities of antioxidant enzymes, Catalase (CAT) and Peroxidase (POD), were activated once microplastics were introduced, and Ascorbate peroxidase (APX) was significantly increased in high microplastics concentrations. The responses of Myriophyllum sp. “Roraima” to microplastics exposure differentiated from those observed in the absence of M. aeruginosa.

Microplastic occurrence in sub-surface waters of the Indonesian archipelago

The issue of plastic pollution in the marine environment is a matter of great concern. Our research presents pioneering findings on sub-surface microplastics in the Indonesian archipelagic waters. Data on microplastic presence in sub-surface water in the Indonesian Archipelagic Water is crucial for expanding our understanding of microplastic distribution from the surface to the bottom layers of the ocean, a research area that has been relatively overlooked. We discovered microplastic particles at 5 m depth below the surface through simultaneous pump method. The highest concentration of microplastics was discovered in Ambon, followed by North Java and North Sulawesi. In contrast, the lowest abundance of microplastics was detected in the Maluku Sea. These findings are consistent with prior studies establishing a relationship between human activity–as indicated by population density–and microplastic pollution. However, our results indicate that levels of microplastics in Ambon were significantly higher than those found in other sampled areas, particularly compared to North Java, which boasts the highest population density in Indonesia. This disparity is likely due to a faster seawater flushing rate and shorter water residence time in North Java relative to Ambon. The origins and pathways through which these microplastics are introduced into Indonesian archipelagic waters remain uncertain. Based on particle composition (52.73% fibers and 51.38% size &amp;lt;500 µm), it appears that they may result from either larger plastic items being broken down during transportation over long distances by prevailing currents from input from coastal areas or as a byproduct of local activities. Additional research is necessary to gain a comprehensive understanding of microplastic in water columns. This includes investigating the fate of microplastics and examining their impact on marine organisms within this treasured ecosystem. Moreover, it is important to develop methods for mapping the worldwide distribution of microplastics.

Distribution and risk assessment of microplastic pollution in a rural river system near a wastewater treatment plant, hydro-dam, and river confluence

Rivers are the natural drainage system, transporting anthropogenic wastes and pollution, including microplastics (plastic < 5 mm). In a riverine system, microplastics can enter from different sources, and have spatial variance in concentration, physical and chemical properties, and imposed risk to the ecosystem. This pilot study presents an examination of microplastics in water and sediment samples using a single sample collection from the rural Raquette River, NY to evaluate a hypothesis that distinct locations of the river, such as downstream of a wastewater treatment plant, upstream of a hydro-dam, and river confluence, may be locations of higher microplastics concentration. In general, our results revealed the presence of high microplastic concentrations downstream of the wastewater treatment plant (in sediments), upstream of the hydro dam (both water and sediment), and in the river confluence (water sample), compared to other study sites. Moreover, the risk assessment indicates that even in a rural river with most of its drainage basin comprising forested and agricultural land, water, and sediment samples at all three locations are polluted with microplastics (pollution load index, PLI > 1; PLIzone = 1.87 and 1.68 for water and sediment samples respectively), with risk categories between Levels I and IV (“minor” to “danger”). Overall, the river stands in a “considerable” risk category (PRIzone = 134 and 113 for water and sediment samples respectively). The overall objective of this pilot study was to evaluate our hypothesis and advance our understanding of microplastic dynamics in rural river systems, elucidating their introduction from a point source (wastewater treatment plant), transit through an impediment (hydro-dam), and release into a vital transboundary river (confluence of Raquette-St. Lawrence Rivers).

Sea surface microplastics in the Galapagos: Grab samples reveal high concentrations of particles

Plastic pollution in the oceans is increasing, yet most global sea surface data is collected using plankton nets which limits our knowledge of the smaller and more bioaccessible size fraction of microplastics (<5 mm). We sampled the biodiverse coastal waters of the Galapagos Island of San Cristobal, comparing two different microplastic sampling methodologies; 1 l whole seawater grab samples filtered to 1.2 μm and sea surface plankton tows with a net mesh size of 200 μm. Our data reveal high concentrations of microplastics in Galapagos coastal waters surrounding the urban area, averaging 11.5 ± 1.48 particles l−1, with a four-order of magnitude increase in microplastic abundance observed using grab sampling compared with 200 μm plankton nets. This increase was greater when including anthropogenic cellulose particles, averaging 19.8 ± 1.86 particles l−1. Microplastic and anthropogenic cellulose particles smaller than 200 μm comprised 44 % of the particles from grab samples, suggesting previous estimates of microplastic pollution based on plankton nets likely miss and therefore underestimate these smaller particles. The particle characteristics and distribution of these smaller particles points strongly to a local input of cellulosic fibres in addition to the microplastic particles transported longer distances via the Humbolt current found across the surface seawater of the Galapagos. Improving our understanding of particle characteristics and distributions to highlight likely local sources will facilitate the development of local mitigation and management plans to reduce the input and impacts of microplastics to marine species, not just in the Galapagos but globally.

Beneath the surface: Decoding the impact of Chironomus riparius bioturbation on microplastic dispersion in sedimentary matrix

A detailed understanding of microplastics (MPs) behaviour in freshwater ecosystems is crucial for a proper ecological assessment. This includes the identification of significant transport pathways and net accumulation zones, considering their inherent, and already proven influence on aquatic ecosystems. Bioavailability of toxic agents is significantly influenced by macroinvertebrates' behaviour, such as bioturbation and burrowing, and their prior exposure history. This study investigates the effect of bioturbation activity of Chironomus riparius Meigen, 1804 on the vertical transfer of polyethylene MPs ex-situ. The experimental setup exposes larvae to a scenario of 10× the environmentally relevant high concentration of MPs (80 g m−2). Bioturbation activity was estimated using sediment profile imaging with luminophore tracers. This study demonstrated that spherical MPs are vertically transferred in the sediment due to the bioturbation activity of C. riparius larvae and that their presence influences the intensity of the bioturbation activity over time. The present findings provide a noteworthy contribution to the understanding of the relationship between ecosystem engineers and the dispersion and accumulation of MPs within freshwater ecosystems.

Exploring the origin and fate of surface and sub-surface marine microplastics in the Canary Islands region

The presence of different types of microplastics (MPs) in the Atlantic Ocean has been well-documented, with data collected from the Canary Islands indicating high concentrations of MPs at four different beaches (hot spots). However, critical gaps persist regarding the abundance of MPs in diverse open ocean regions, at varying depths, and their transport behavior and origin. This study aims to evaluate, for the first time, the large-scale (&amp;gt;100 km) and mesoscale (10-100 km) ocean dynamic processes and the resulting transport of MPs in the region. On the one hand, this study investigates the surface velocity of currents between 27-32°N latitude range, establishing correlation with the accumulation of MPs on diverse beaches across several islands of the archipelago. This analysis goes beyond studying the predominant current by integrating data at a smaller geographical scale over a two-year period. Concurrently, previous and ongoing research suggests the presence of small MPs (SMPs,&amp;lt;1 mm) at high concentration at a depth of 1100 meters in this region. By integrating these vertical profiles of MPs with a deep understanding of the physical processes of the Canary region accumulated over decades of research, our study introduces an innovative model that outlines how SMPs are sink and transported in open oceans by water mases. This comprehensive approach not only enhances our understanding of the complex dynamics influencing the distribution of MPs but also provides crucial insights to address the widespread problem of MP pollution in the Atlantic.