Coarse microplastic accumulation patterns in agricultural soils during two decades of different urban composts application.

Plastic pollution, a global threat to environmental and human health, is now ubiquitous in the environment, including agricultural soils receiving urban compost amendments. Yet, the accumulation pattern of microplastics in soils are still to be disentangled, with regards to their sources and/or their physical properties such as morphotypes. The aim of this study was to identify the accumulation patterns of coarse microplastics (CMP) resulting from the long-term amendment of soil with urban waste composts. To this end, we used a field experiment receiving three different urban composts derived from municipal solid waste, biowaste, and a mixture of sewage sludge and green waste. We isolated 1417 coarse microplastic particles from a 21-year archive of soil and compost samples, using density fractionation followed by oxidation, and used Py-GC/MS for polymer identification. Different compost types led to different coarse microplastics accumulation levels. The accumulation pattern showed increasing CMP contents in soils over time. After 21 years of experiment, the calculated number of CMP was in accordance with the estimated values for all three compost types but it was not the case for the CMP mass. No difference of evolution pattern was found between films and fragments. We proposed that biotic transport or abiotic weathering and fragmentation could explain such differences in CMP evolution pattern.

Microplastic from beach sediment to tissue: a case study on burrowing crab Dotilla blanfordi.

Background: Microplastics (MPs) are pervasive pollutants in the marine environment, exhibiting persistence in coastal sediment over extended periods. However, the mechanism of their uptake by marine organisms and distribution in habitat is less understood. The objective of the present study was to investigate the presence of MP contamination in burrow sediment, feeding pellets, and tissue of Dotilla blanfordi in the Gulf of Kachchh, Gujarat State. Methods: A total of 500 g of burrow sediment, 100 g of feeding pellets, and body tissue of 10 resident D. blanfordi were pooled as one replica. Such seven replicas from each site were analyzed for MP extraction from three sites, including Asharmata, Mandvi, and Serena, located in the Gulf of Kachchh. The standard protocol was used during the analysis of the collected samples in order to isolate MPs. Results: The abundance of MP was found higher in burrow sediment, feeding pellets and tissue of D. blanfordi at study site Mandvi, followed by Serena and Asharmata. The abundance of MP was found higher in D. blanfordi tissue, followed by burrow sediment and feeding pellet. A significant variation was observed in MP abundance among burrow sediment, feeding pellets, and tissue. MPs with various shapes (fiber, film, and fragment), sizes (1-2, 2-3, 3-4, and 4-5 mm), and colors (blue, green, black, pink, purple, red transparent) were recorded from all the study sites. Polyurethane and polyvinyl chloride were recognized as the chemical profile of the extracted MPs. The current investigation revealed greater accumulation of MPs in D. blanfordi's tissues compared to sediment and pellets, suggesting a risk of MP contamination in marine benthic fauna with a greater rate of bioaccumulation. D. blanfordi plays a significant role as a structuring agent for MP distribution in the intertidal flat through burrowing activity.

Sustainable struggling: decoding microplastic released from bioplastics-a critical review.

This comprehensive review delves into the complex issue of plastic pollution, focusing on the emergence of biodegradable plastics (BDPs) as a potential alternative to traditional plastics. While BDPs seem promising, recent findings reveal that a large number of BDPs do not fully degrade in certain natural conditions, and they often break down into microplastics (MPs) even faster than conventional plastics. Surprisingly, research suggests that biodegradable microplastics (BDMPs) could have more significant and long-lasting effects than petroleum-based MPs in certain environments. Thus, it is crucial to carefully assess the ecological consequences of BDPs before widely adopting them commercially. This review thoroughly examines the formation of MPs from prominent BDPs, their impacts on the environment, and adsorption capacities. Additionally, it explores how BDMPs affect different species, such as plants and animals within a particular ecosystem. Overall, these discussions highlight potential ecological threats posed by BDMPs and emphasize the need for further scientific investigation before considering BDPs as a perfect solution to plastic pollution.

Presence of microplastics in the groundwater of volcanic islands, El Hierro and La Palma (Canary Islands).

The increasing amount of plastic litter worldwide is a serious problem for the environment and its biodiversity, ecosystems, animal and human welfare and the economy. The degradation of these plastics leads to microplastics (MPs), which have been reported for the first time in groundwater in the Canary archipelago. This research investigates the presence of MPs at nine different points on La Palma and El Hierro, where samples were collected in galleries, wells and springs during the month of December 2022. Six different polymers were found with Fourier transform infrared spectroscopy (FTIR) - polypropylene (PP), polyethylene (PE), cellulose (CEL), polyethylene terephthalate (PET), polystyrene (PS) and polymethyl methacrylate (PMMA). The particle concentrations found ranged from 1 to 23 n/L, with a maximum particle size of 1900 µm, the smallest being 35 µm. PP and PE were the most common polymers found in the analysis, associated with the use of packaging, disposable products, textiles and water pipes, related to poorly maintained sewerage networks where leaks occur, allowing these MPs to escape into the environment and end up in groundwater. The detection of microplastic pollution in groundwater emphasises environmental hazards, including biodiversity disruption and water source contamination. Additionally, it presents potential risks to human health by transferring contaminants into the food chain and through respiratory exposure.

Arbuscular Mycorrhizal Fungi Can Inhibit the Allocation of Microplastics from Crop Roots to Aboveground Edible Parts.

Microplastics are emerging pollutants that threaten soil health and food safety. Recently, there has been increasing interest in understanding the behavior of these particles in the rhizosphere, specifically regarding the potential uptake of microplastics into crops. Arbuscular mycorrhizal (AM) fungi are widespread soil fungi, forming symbiotic associations with most terrestrial plants. Therefore, it is essential to investigate if AM fungi could protect crops from microplastics in soil. Here, we grew vegetables (Lactuca sativa) inoculated with/without the AM fungus Rhizophagus irregularis at various levels of poly(methyl methacrylate) (PMMA) soil pollution (0, 0.05, 0.1, 0.2, and 0.4%, mass ratio of the pollutant to soil). Our findings revealed that the proportion of transport of PMMA from roots to shoots decreased significantly in mycorrhizal crops. This reduction occurred because some PMMA particles were immobilized by AM vesicles and intraradical fungal hyphae. However, AM symbiosis did not substantially reduce the uptake of microplastics by crops from soil. Mycorrhizal fungi might enhance the resistance of crops to microplastics through transforming the chemical properties of microplastics, reducing their complexation to crop components, and promoting crop phosphorus nutrition at high microplastic addition levels. Our study is the first report to achieve rapid quantification of microplastics in mycorrhizal crops using microscale combustion calorimetry, demonstrating that AM fungi have the ability to immobilize microplastics. The study allows a deeper insight into microplastic behavior in AM-associated crops and supports the potential application of AM fungi in crop cultivation under microplastic contamination.

Temporal trends in microplastic accumulation in placentas from pregnancies in Hawai'i.

Microplastics are created for commercial use, are shed from textiles, or result from the breakdown of larger plastic items. Recent reports have shown that microplastics accumulate in human tissues and may have adverse health consequences. Currently, there are no standardized environmental monitoring systems to track microplastic accumulation within human tissues. Using Raman spectroscopy, we investigated the temporal exposures to plastic pollution in Hawai'i and noted a significant increase in the accumulation of microplastics in discarded placentas over the past 15 years, with changes in the size and chemical composition of the polymers. These findings provide a rare insight into the vulnerability and sensitivity of Pacific Island residents to plastic pollution and illustrate how discarded human tissues can be used as an innovative environmental plastic pollution monitoring system.

Unveiling the hidden threat of microplastics to coral reefs in remote South Atlantic islands.

The widespread presence of marine microplastics (< 5 mm) is a significant concern, as it may harm marine biodiversity and ocean ecosystems. Corals' capacity to ingest microplastics has emerged as a significant threat to reef ecosystems, owing to the detrimental physiological and ecological effects it can trigger. The extent of the impact of microplastics on Brazilian corals remains unclear and this study aimed to investigate its distribution and characteristics in four coral species: Favia gravida, Mussismilia hispida, Montastrea cavernosa, and Siderastrea stellata, found in the Trindade and Martim Vaz Islands - the most isolated archipelago of Brazil, located about 1200 km (680 miles) east of the coast. This study aims to reveal the extent of microplastic distribution in the coral reef environment, assess the amount of microplastics in different coral species, and compare each species' capacity to adhere and accumulate microplastics. A high concentration of ingested and adhered microplastics was detected in all coral species evaluated in the present study. No significant differences were observed in the sampling points which indicates that although the sampling points are located at different distances from the coast, the microplastic pollution is equally distributed in the region. Polyethylene (PE), polyvinyl chloride (PVC), polypropylene (PP), poly(methyl methacrylate) (PMMA), Rayon, and Nylon particles were detected, with a predominance of PE (45.5 %). No significant differences in microplastic concentration were detected among the various species and locations studied. Our research presents findings that demonstrate the extensive occurrence of microplastic contamination in coral colonies located on remote islands.

Environmentally relevant concentrations of microplastics modulated the immune response and swimming activity, and impaired the development of marine medaka Oryzias melastigma larvae.

Microplastics (MPs), due to their impacts on the ecosystem and their integration into the food web either through trophic transfer or ingestion directly from the ambient environment, are an emerging class of environmental contaminants posing a great threat to marine organisms. Most reports on the toxic effects of MPs exclusively focus on bioaccumulation, oxidative stress, pathological damage, and metabolic disturbance in fish. However, the collected information on fish immunity in response to MPs is poorly defined. In particular, little is known regarding mucosal immunity and the role of mucins. In this study, marine medaka (Oryzias melastigma) larvae were exposed to 6.0 µm beads of polystyrene microplastics (PS-MPs) at three environmentally relevant concentrations (102 particles/L, 104 particles/L, and 106 particles/L) for 14 days. The experiment was carried out to explore the developmental and behavioural indices, the transcriptional profiles of mucins, pro-inflammatory, immune, metabolism and antioxidant responses related genes, as well as the accumulation of PS-MPs in larvae. The results revealed that PS-MPs were observed in the gastrointestinal tract, with a concentration- and exposure time-dependent manner. No significant difference in the larval mortality was found between the treatment groups and the control, whereas the body length of larvae demonstrated a significant reduction at 106 particles/L on 14 days post-hatching. The swimming behaviour of the larvae became hyperactive under exposure to 104 and 106 particles/L PS-MPs. In addition, PS-MP exposure significantly up-regulated the mucin gene transcriptional levels of muc7-like and muc13-like, however down-regulated the mucin gene expression levels of heg1, muc2, muc5AC-like and muc13. The immune- and inflammation and metabolism-relevant genes (jak, stat-3, il-6, il-1ß, tnf-а, ccl-11, nf-κb, and sod) were significantly induced by PS-MPs at 104 and 106 particles/L compared to the control. Taken together, this study suggests that PS-MPs induced inflammation response and might obstruct the immune functions and retarded the growth of the marine medaka larvae even at environmentally relevant concentrations.

Uptake and accumulation of microplastic particles by two freshwater ciliates isolated from a local river in South Africa.

Microplastics are considered environmental pollutants of serious concern. In freshwater environments, they can affect aquatic biota and accumulate along the food web. Therefore, this study investigated the capacity of bacterivorous freshwater ciliates, essential members of the aquatic food chain, to ingest plain and fluorescently-labeled polystyrene microspheres. Two holotrich ciliates were isolated from a stream in KwaZulu-Natal (South Africa) and identified as members of the genera Paramecium and Tetrahymena based on morphological characteristics and 18S rRNA gene sequence analysis. While the larger bacterivorous ciliate Paramecium sp. strain RB1 ingested all three sizes of plain polystyrene microbeads tested (2,5,10 µm), the smaller sized Tetrahymena sp. strain RB2 only ingested microbeads of 2 and 5 µm. The two ciliates ingested polystyrene microbeads at rates ranging from 1650 to 3870 particles x ciliate-1 x hour-1 for all particle sizes ingested, matching rates determined for selected microbial prey (E. coli, S. cerevisiae) of similar size. The ability to ingest non-nutritious microplastic particles was confirmed for both ciliates using fluorescently-labeled microbeads as these were detected in food vacuoles by fluorescence microscopy. Therefore, ciliates such as Paramecium sp. strain RB1 and Tetrahymena sp. strain RB2 can contribute to the transfer and bioaccumulation of microplastics in freshwater food webs in South Africa.

The Role of Ekman Currents, Geostrophy, and Stokes Drift in the Accumulation of Floating Microplastic.

Floating microplastic in the oceans is known to accumulate in the subtropical ocean gyres, but unclear is still what causes that accumulation. We investigate the role of various physical processes, such as surface Ekman and geostrophic currents, surface Stokes drift, and mesoscale eddy activity, on the global surface distribution of floating microplastic with Lagrangian particle tracking using GlobCurrent and WaveWatch III reanalysis products. Globally, the locations of microplastic accumulation (accumulation zones) are largely determined by the Ekman currents. Simulations of the North Pacific and North Atlantic show that the locations of the modeled accumulation zones using GlobCurrent Total (Ekman+Geostrophic) currents generally agree with observed microplastic distributions in the North Pacific and with the zonal distribution in the North Atlantic. Geostrophic currents and Stokes drift do not contribute to large-scale microplastic accumulation in the subtropics, but Stokes drift leads to increased microplastic transport to Arctic regions. Since the WaveWatch III Stokes drift and GlobCurrent Ekman current data sets are not independent, combining Stokes drift with the other current components leads to an overestimation of Stokes drift effects and there is therefore a need for independent measurements of the different ocean circulation components. We investigate whether windage would be appropriate as a proxy for Stokes drift but find discrepancies in the modeled direction and magnitude. In the North Pacific, we find that microplastic tends to accumulate in regions of relatively low eddy kinetic energy, indicating low mesoscale eddy activity, but we do not see similar trends in the North Atlantic.

Effects of microplastics on sessile invertebrates in the eastern coast of Thailand: An approach to coastal zone conservation.

This study assessed the microplastic contamination of 3 most abundant sessile and intertidal invertebrates (Rock Oyster: Saccostrea forskalii, Striped Barnacle: Balanus amphitrite, Periwinkle: Littoraria sp.) in 3 beaches of the eastern coasts of Thailand. The results showed a significant accumulation of microplastics in the invertebrates at rates of 0.2-0.6 counts/g indicating higher pollution levels along the coastline. Filter feeding organisms showed comparatively higher accumulation rates of microplastics. Thus, contaminated bivalves pose potential health risks for seafood consumers. The plastic pollutant prevalence in sessile and intertidal communities was corresponded with pollution characteristics of contaminated beach habitats where they live. Thus, bivalves, gastropods and barnacles can be used as indicators for contamination of microplastics in the areas. This study also demonstrated the need for controlling plastic pollution in Thai coastal areas.