Uptake and accumulation of microplastics in a cereal plant wheat

Microplastic (MP, 100 nm−5 mm) may present an attributable risk to ecosystem and human health, and its pollution has become a global environmental concern. Despite a wealth of information on the accumulation of MPs in aquatic species, there is no information on the uptake and accumulation of MPs by higher plants. Terrestrial edible plants are directly exposed to MPs when agricultural soil was applied with organic manure, sewage sludge as fertilizer or plastic mulching. In this paper, the uptake of two sizes of polystyrene (PS) microbeads (0.2 and 1.0 μm) and then their distribution and migration in an edible plant lettuce were firstly investigated based on laboratory experiments. We used fluorescent markers to track PS microbeads in plant tissues and found fluorescence to be a sensitive and reliable detection method. Sections from untreated control lettuce showed no autofluorescence. When roots were treated with fluorescently labeled PS microbeads, the microbeads could be identified by its fluorescence. Our main study investigated the uptake of 0.2 μm beads, as few luminescence signals were observed in lettuce roots for 1.0 μm beads in our experiment. We observed that 0.2 μm fluorescent microbeads were extracellularly trapped in the root cap mucilage (which is a highly hydrated polysaccharide) and a “dark green tip” (which was typical of lettuce roots exposed to label PS beads) was usually visible to the naked eye. Confocal images revealed that the PS luminescence signals were mainly located in the vascular system and on the cell walls of the cortex tissue of the roots, indicated that the beads passed through the intercellular space via the apoplastic transport system. Once inside the central cylinder, the 0.2 μm PS beads were transferred from the roots to the stems and leaves via the vascular system following the transpiration stream. We also observed that the PS beads adhered to one another and self-assembled systematically into “grape-like” and “(chain) string-like” clusters in the intercellular space of the root and stem vascular tissue of lettuce plant. In contrast to the root and stem, PS beads were dispersed in the leaf tissue. Here, for the first time we provide evidence of the adherence, uptake, accumulation, and translocation of submicrometer MPs within an edible plant. Our findings highlight the previously underappreciated human exposure pathway to MPs through the consumption of contaminated crops and emphasize the need for new management strategies to control the release of MPs waste products into the terrestrial environment. Ultimately, the potential impacts of low range sized MPs on food safety of crop plants and human health need to be urgently considered.

Uptake and distribution of microplastics of different particle sizes in maize (Zea mays) seedling roots

Accumulation, tissue distribution, and biochemical effects of polystyrene microplastics in the freshwater fish red tilapia (Oreochromis niloticus)

The uptake and accumulation of microplastics (MPs) by bloodsucking mosquitoes Aedes aegypti L., carriers of vector-borne diseases, were investigated in the laboratory. In the experimental group, polystyrene (PS) particles were registered in insects of all life stages from larvae to pupae and adults. Ae. aegypti larvae readily ingested MPs with food, accumulating on average 7.3 × 106 items per larva in three days. The content of PS microspheres significantly decreased in mosquitoes from the larval stage to the pupal stage and was passed to the adult stage from the pupal without significant loss. On average, 15.8 items were detected per pupa and 10.9 items per adult individual. The uptake of MPs by Ae. aegypti did not affect their survival, while the average body weight of mosquitoes of all life stages that consumed PS microspheres was higher than that of mosquitoes in the control groups. Our data confirmed that in insects with metamorphosis, MPs can pass from feeding larvae to nonfeeding pupae in aquatic ecosystems and, subsequently, to adults flying to land. Bloodsucking mosquitoes can participate in MP circulation in the environment.

ABSTRACTThis study aimed to (i) monitor on the 1st, 5th, and 10th days the microplastics (MP) presence and bioaccumulation in different organs (gill, digestive tract, remaining tissue) of the oysters exposed to 100 MP L−1; and (ii) evaluate the MP elimination proportion out of the oysters after 1, 5, 10, and 30 days of the depuration experiment. We found that the accumulation of MP was higher in the digestive tract and remaining tissues than in the gills of the oysters. The average bioaccumulation factors were 10.11, 14.25, and 40.92 for 1, 5, and 10 days of incubation, respectively. Generally, the longer the time of MP exposure, the higher the MP bioaccumulation is in the organs and tissue of the oysters. High elimination proportion of MP in the gill (77.4%), digestive tract (74.4%), remaining tissue (62.3%), and the whole body (70.2%) of the oysters was observed after the 1st day of the depuration experiment. The elimination proportion in each tissue continued to increase linearly with time during the depuration period. After 1 month of depuration, the elimination rate in the gill, digestive tract, remaining tissue, and whole body of the oysters was 83.9%, 91.0%, 91.3%, and 89.9%, respectively. This work contributes to a better understanding of the uptake and distribution of MP in different organs and tissues of the oysters. At least 10 days of MP depuration out of the MP‐contaminated oysters is suggested to minimize the MP exposure via food consumption.

To combat the plastic problem in the marine environment, bioindicators are essential because they can provide insights into the extent and ecological impacts of plastic pollution. The ingestion and accumulation of microplastics (MPs) in the striped barnacle Amphibalanus amphitrite was studied by exposing them to MPs with or without biofilm. Three types (polyethylene, polystyrene/polyester), two sizes (27-32 µm and 90-106 µm) and two forms (microspheres and microfibers) of MPs at three concentrations (7.2, 72 and 720 P/mL) were investigated. The presence of biofilm did not affect the MP ingestion. The ingestion of MPs was concentration-dependent, irrespective of the size, form and type of the MPs. The numbers of microspheres and microfibers ingested by A. amphitrite were similar, and so were their numbers accumulated in the body. The results suggest a lack of both pre-ingestive and post-ingestive sorting and removal of MPs in A. amphitrite. The MP body burden, therefore, reflects levels of environmental contamination and the actual MPs composition in the water body. Considering the global distribution of A. amphitrite and its high abundance on rocky shores and man-made structures such as wharf piles, ease of finding and sampling, clear taxonomic status, small body size, high reproductive rate, specialized feeding mode, and well-known biology and life history, it has great potential to be considered as a member of a list of global marine bioindicators of MPs. Further investigations should focus on how seasonal changes in environmental factors and body conditions, such as reproductive cyclicity, influence the ingestion and accumulation of MPs, and the associated ecotoxicological effects.

An increase in global infertility has coincided with the accumulation of microplastics (MPs) in the environment. This trend is particularly troubling because only 10% of male infertility cases can be attributed to identifiable causes, leaving a knowledge gap in our understanding of their underlying factors. To bridge this, it is important to explore the connection between the accumulation of MPs and the observed decline in male fertility. We assessed the presence of microplastics in epididymal sperm from bulls and used it as baseline concentrations for sperm exposure. MPs were detected in all epidydimal sperm (ES) samples, with a mean concentration of 0.37μgmL-1. Next, to investigate the effects of MPs on fertility, bovine sperm was exposed to three different concentrations of a mixture of 1.1, 0.5, and 0.3μm polystyrene (PS) beads: (1) 0.7μgmL-1, blood concentration of PS in cows (bPS); (2) 0.37μgmL-1, based on the concentration of total MPs found in ES (esMP); and (3) 0.026μgmL-1, based on the concentration of PS found in ES (esPS). All sperm samples incubated with PS exhibited reduced motility compared with the control at 0.5h. However, PS exposure did not affect acrosome integrity or induced oxidative stress. Embryos produced from sperm exposed to PS had reduced blastocyst rates, in addition to increased ROS formation and apoptosis. By employing physiological exposure, this research provided evidence of MPs in bovine epididymal sperm and demonstrated the detrimental effect of PS on sperm functionality.

Effects of sizes and concentrations of different types of microplastics on bioaccumulation and lethality rate in the green mussel, Perna viridis

Migration and accumulation of microplastics in soil-plant systems mediated by symbiotic microorganisms and their ecological effects

As a new type of environmental pollutant, microplastic has been widely found in the aquatic environment and poses a high threat to aquatic organisms. The bioaccumulation of microplastics plays a key role in their toxic effects; however, as a particulate, their bioaccumulations are different from many other pollutants. Described here is a feasible method to visually determine the accumulation and distribution of microplastics in zebrafish embryos or larvae using fluorescent microplastics. Embryos are exposed to different concentrations (0.1, 1, and 10 mg/L) of fluorescent microplastics with a diameter of 500 nm for 120 h. It is shown in the results that microplastics can bioaccumulate in zebrafish embryos/larvae in a concentration-dependent manner. Before hatching, strong fluorescence is found around the embryonic chorion; while in zebrafish larvae, the yolk sac, pericardium, and gastrointestinal tract are the main accumulated sites of microplastics. The results demonstrate the uptake and internalization of microplastics in zebrafish at early life stages, which will provide basis for better understanding the impact of microplastics on aquatic animals.

An effective procedure was demonstrated to arrange spherical micro-beads into ordered, long, line-shape arrays by means of ``micromolding in capillaries'' in soft lithography. Polystyrene (PS) micro-beads with 2-3mm of diameter were used as units and arranged by molding in continuous micro-channels formed by the conformal contact between a glass substrate and an elastomeric stamp with micrometer-scale line patterns on the surface. An aqueous emulsion of PS micro-beads filled these channels by capillary action and was allowed to solidify. The stamp was then removed. The PS micro-beads could be assembled into a string of long line-shape arrays, and the strings were then joined by heating them to their softening temperature. In order to separate the PS micro-bead string from the substrate, the glass was covered with a thin layer of Al or polymethyl methacrylate. After the Al layer was dissolved, the string of PS micro-beads would be released. A string of micrometer scale PS beads can be used as a simple and direct ``model'' of a real macromolecular chain. It is hopeful to show an analogue with the condensed process of real macromolecules in a mesoscopic scale using the ``string of PS micro-beads''.

Insights into microplastic exposure routes in the earthworm (Eisenia fetida): Gut and skin.

Uptake, accumulation and associated cellular alterations of environmental samples of microplastics in the seaworm Hediste diversicolor

Small plastic detritus, termed "microplastics", are a widespread and ubiquitous contaminant of marine ecosystems across the globe. Ingestion of microplastics by marine biota, including mussels, worms, fish, and seabirds, has been widely reported, but despite their vital ecological role in marine food-webs, the impact of microplastics on zooplankton remains under-researched. Here, we show that microplastics are ingested by, and may impact upon, zooplankton. We used bioimaging techniques to document ingestion, egestion, and adherence of microplastics in a range of zooplankton common to the northeast Atlantic, and employed feeding rate studies to determine the impact of plastic detritus on algal ingestion rates in copepods. Using fluorescence and coherent anti-Stokes Raman scattering (CARS) microscopy we identified that thirteen zooplankton taxa had the capacity to ingest 1.7-30.6 μm polystyrene beads, with uptake varying by taxa, life-stage and bead-size. Post-ingestion, copepods egested faecal pellets laden with microplastics. We further observed microplastics adhered to the external carapace and appendages of exposed zooplankton. Exposure of the copepod Centropages typicus to natural assemblages of algae with and without microplastics showed that 7.3 μm microplastics (>4000 mL(-1)) significantly decreased algal feeding. Our findings imply that marine microplastic debris can negatively impact upon zooplankton function and health.

Studies on the ingestion and accumulation of microplastics (MPs) by river fish in various regions worldwide are crucial for a deeper understanding of MP cycles and for assessing food safety. This paper presents data on the quantitative assessment of MP and viscose fiber (0.15-5mm) ingestion by several fish species inhabiting the rivers of the Syr Darya basin in the Republic of Uzbekistan and an ecological risk assessment based on the polymer hazard index (PHI). The average MP concentration in fish gastrointestinal (GI) tracts (n = 61) attained 2.61 ± 4.38 items/ind, or 11.5 ± 43.8μg/ind. The MP concentration normalized to total body weight was 86.3 ± 130 items, or 241 ± 636μg/kg. Particles were predominantly fibers. Microplastic ingestion by fish from the Kara Darya and Chirchiq rivers did not differ significantly. No differences were observed between species, and between fish of different sexes and juveniles. Furthermore, no correlation was found between MP ingestion by fish and their trophic level. However, a significant (p < 0.05) correlation was revealed between the MP concentration in GI tracts and linear-weight parameters of fish. MP polymers predominant in fish from the Syr Darya basin included mainly PE, PET, PP, and polyethersulfon (PES) plastics. In addition to PES, "minor" polymers, such as PAN, PUR, and PVC, contributed to the ecological risk associated with polymer toxicity. The ecological risk for MPs extracted from the collected fish specimens was assessed based on the PHI and categorized as moderate (hazard category III). The study provides the first experimental evidence of MP ingestion by freshwater fish in the rivers of the Syr Darya basin. The data obtained can be used for the quantitative assessment of global plastic pollution and its threat to environmental components, including living systems, as well as for the ecological risk assessment.