Study on the photoaging process and metal ion release of plastic films with two kinds of structures in marine environment: Aliphatic and aromatic polymers.

The prevalence of plastics in the oceans has significantly intensified microplastic pollution, contributing to broader marine secondary pollution issues. This paper examines how plastic structure affects the aging characteristics of plastics and the release of metal ions, to better understand this secondary source of marine pollution. This study simulate the photoaging of plastics in natural environments, focusing on aliphatic and aromatic polymers. The results showed that the photodegradation degree was higher for aliphatic than aromatic polymers. All polymers contained thirteen detectable metals, with their release increasing over time due to photoaging, The release dynamics of these metal ions correlated more strongly with the level of polymer degradation rather than with the polymer structure itself, adhering to a second-order kinetic model driven by surface and intraparticle diffusion processes. The results will help control and treat marine plastic pollution.

Microscopic dissolution process of cellulose in alkaline aqueous solvents and its application in CNFs extraction - Investigating temperature as a variable.

The target of this study is to gain a deeper understanding of the micro-dissolution process of cellulose in alkaline aqueous solutions and to develop a novel method for extracting cellulose nanofibrils (CNFs). Herein, the dissolution process of cellulose in alkaline aqueous solutions will be controlled by varying the temperature, and the undissolved cellulose will be analyzed to reveal the microscopic dissolution process of cellulose, and a novel process for extracting cellulose nanofibrils (CNFs) will be developed based on the findings. The crystalline structure of cellulose was gradually disrupted as the dissolution progressed, and the crystal form of cellulose changed gradually from cellulose I to cellulose II during the dissolution process, while all undissolved cellulose crystals remained as cellulose I. Cellulose, after its structure is disrupted during the dissolution process, will inevitably decompose into CNFs, and the microscopic dissolution process of cellulose follows a "top-down" dissolution sequence. The CNFs extraction method developed in this study can extract CNFs with high yield (>60 %) in a stable manner, as well as narrow particle size distribution, high crystallinity (>77 %), and good thermal stability. This study enhances the comprehension of the dissolution process of cellulose and paves a possible way for industrialization of CNFs production.

Multidecadal heavy metals and microplastic deposition records in an urban lake: the ecological risk assessments and influencing factors.

With the development of urbanization and economic growth, the urban lake ecosystem faces many challenges derived from external factors. As pollutants in the aquatic environment, heavy metals and microplastics negatively influence the urban lake ecosystem due to their intrinsic properties. To understand the distribution patterns and multidecadal deposition characteristics of heavy metals and microplastics, six sediment cores were collected in March 2021 from a Chinese urban lake, Xinghu Lake, and the isotopic composition of cesium-137 and lead-210 was analyzed for the chronology of the sediment core. Here, the classifications of comprehensive ecological risk evaluation methods for heavy metals and microplastics were adjusted further. Meanwhile, the correlations among heavy metals, microplastics, sediment grains, and natural and social factors were further analyzed. The results showed that the sediments of Xinghu Lake were mainly fine silt (39%), and the average surface area of sediment was 1.82 ± 0.60 m2/g. The average concentrations of cadmium, chromium, copper, nickel, lead, vanadium, and zinc were 0.268 ± 0.077, 59.91 ± 16.98, 23.29 ± 6.48, 52.16 ± 13.11, 36.83 ± 11.78, 119.57 ± 26.91, and 88.44 ± 29.68 mg/kg, respectively. The average comprehensive potential ecological risk indexes of heavy metals and microplastics in sediment cores were 46.59 ± 9.98 and 105.78 ± 23.32 in Xinghu Lake, and their risks were projected to reach high and very high levels by 2030 and 2050. The annual average temperature was the key natural factor for the abundances of heavy metals and microplastics, and the small sediment grain had a significant correlation with these. Agricultural activities were major pollution sources of heavy metals and microplastics, while the chemical fibers and plastic products were closely related to the abundance of microplastics.

Source or sink role of an urban lake for microplastics from Guangdong-Hong Kong-Macao greater bay area, China.

Plastic production and consumption in China are larger than others in the world, and the challenge of microplastic pollution is widespread. With the development of urbanization in the Guangdong-Hong Kong-Macao Greater Bay Area, China, the environmental pollution of microplastics is becoming an increasingly prominent issue. Here, the spatial and temporal distribution characteristics, sources, and ecological risks of microplastics were analyzed in water from an urban lake, Xinghu Lake, as well as the contribution of rivers. Importantly, the roles of urban lakes for microplastics were demonstrated through the investigations of contributions and fluxes for microplastic in rivers. The results showed that the average abundances of microplastics in water of Xinghu Lake were 4.8 ± 2.2 and 10.1 ± 7.6 particles/m3 in wet and dry seasons, and the average contribution degree of the inflow rivers was 75%. The size of microplastics in water from Xinghu Lake and its tributaries was concentrated in the range of 200-1000 µm. In general, the average comprehensive potential ecological risk indexes of microplastics in water were 247 ± 120.6 and 273.1 ± 353.7 in wet and dry seasons, which the high ecological risks of them were found through the adjusted evaluation method. There were also mutual effects among microplastic abundance, the concentrations of total nitrogen and organic carbon. Finally, Xinghu Lake has been a sink for microplastics both in wet and dry seasons, and it would be a source of microplastics under the influence of extreme weather and anthropogenic factors.

Occurrence and sources of microplastics and polycyclic aromatic hydrocarbons in surface sediments of Svalbard, Arctic.

Due to the distinct environment condition and geographic location, Svalbard has been recognized as a potential pollution reservoir in the Arctic. In this study, 8 surface sediment samples were collected from two fjords in Svalbard (Kongsfjorden and Rijpfjorden) in 2017, and they were searched for microplastics and polycyclic aromatic hydrocarbons (PAHs). PAHs were also investigated in 10 soil samples of Ny-Ålesund for local anthropogenic source analysis. The level of microplastics and other anthropogenic particles ranged from not detected (ND) to 4.936 particles/kg dry weight (DW). Fiber was the only shape of the microplastics found and three polymers (polyester, rayon and cellulose) were detected, which suggested that fisheries-related debris and textile materials were possible sources of microplastics and anthropogenic particles. For PAHs, the level of ∑26PAH was 9.2 ng/g to 67.1 ng/g (DW), and were dominated by lnP and BghiP, indicating petroleum combustion source. Further analysis revealed that traffic emissions from cars and diesel combustion from a local power plant were major sources of PAHs in soils of Ny-Alesund, while traffic emissions from ships were the dominate source of PAHs in sediments of Kongsfjorden and Rijpfjorden. A higher level of PAHs was observed in Ny-Alesund, confirming an anthropogenic input, while transport via ocean currents might contribute to the higher abundance of microplastics in Rijpfjorden. Further research and even long-term observation of pollutants are needed to fully understand the pollution status in polar regions.

Protein-coated microplastics corona complex: An underestimated risk of microplastics.

Traditionally, toxicity of microplastics is ascribed to the chemicals adsorbed on them. However, microplastics can also interact with biomolecules, such as secretory proteins from aquatic organisms, and form protein-coated microplastics corona complex with unknown toxic effects. Here, we investigated the toxic effects of polystyrene microplastics (PS) and bovine serum albumin (BSA) coated PS corona complex (PS + BSA) on adult zebrafish (Danio rerio) intestines. The food intake ratio, accumulation and distribution of microplastics, histopathological changes, and molecular effects related to the antioxidant system in the intestine were studied. For the first time, we observed that PS + BSA aggregated on the inner surface of the zebrafish intestine, whereas PS dispersed. The aggregation of PS + BSA resulted in increased microplastics accumulation and longer residence time in the zebrafish intestine, which inhibited food intake and generated reactive oxygen species (ROS) in the intestine. Furthermore, the functions of the Keap1-Nrf2-ARE antioxidant signaling pathway and the activation of antioxidant enzymes were significantly affected by PS + BSA after a 21-day exposure. Ultimately, a higher accumulation of ROS and stronger inhibition of antioxidants led to more severe intestinal injury. These results suggest that the increased toxicity of protein-coated microplastics corona complex may be affected by oxidative damage and can result in the inhibition of digestion due to their aggregation and longer residence time in the intestine. Therefore, the ecological risk of microplastics may be underestimated owing to the interactive mechanisms of microplastics and protein coronas.

Microplastics contamination in bivalves from the Daya Bay: Species variability and spatio-temporal distribution and human health risks.

Microplastic contamination is an emerging global threat for various marine organisms. Marine invertebrates such as bivalve mollusks are more susceptible to the widespread presence of microplastics due to their limited abilities to escape from pollution exposure and they can readily ingest environmental pollutants like microplastics through their filter-feeding behaviors. In this study, microplastic contamination in bivalves related to species, spatial, and temporal variability were conducted. Results showed that the frequency of microplastic occurrence varied from 86.7 % to 93.3 % in six species of bivalves, and the average abundance of microplastics ranged from 3.5 to 8.6 items per individual or from 0.2 to 3.1 items per gram tissues wet weight. No significant difference was observed in microplastic abundances of bivalves collected from different research regions and sampling seasons. However, the sediment-dwelling bivalves had higher microplastics abundances than the water-dwelling bivalves. Microplastic features with various shapes, colors, sizes, and polymer types detected in bivalves were similar with those in seawater and sediment environments that they are living in. The potential risk assessment of microplastics in bivalves basing on polymer hazard index (PHI) was in the risk levels of II-III, implying that microplastic contamination in bivalves may pose health risk to human via seafood consumption.

Effects of different treatment processes in four municipal wastewater treatment plants on the transport and fate of microplastics.

The behavior of microplastics in wastewater treatment plants has been investigated, but specific effects of treatment process on microplastics' fate are still unclear due to varied analysis methods and regional differences. In this study, four wastewater treatment plants in Ningbo of southeastern China with different treatment processes were selected to investigate transport and fate of microplastics. Based on number of microplastic particles, fibers and fragments were the main microplastics types in wastewater, while synthetic cellulose represented the largest fraction. The dominance of fibers (76.7%-90.0%) and small particle sizes (<2.0 mm, 62.5%-81.5%) in effluents suggested that they escaped easily from the wastewater treatment plants. The abundance of microplastics particles decreased from 78.0 ± 2.9 items/L in influent to 6.0 ± 2.8 items/L in effluent for anaerobic-anoxic-oxic process, 100.0 ± 3.1 items/L to 4.3 ± 3.4 items/L for sequencing batch reactor activated sludge process, 105.0 ± 5.3 items/L to 3.5 ± 2.6 items/L for cyclic activated sludge technology, 65.0 ± 4.3 items/L to 3.0 ± 1.6 items/L for oxidation ditch process. The microplastics removal capacity of primary and secondary treatment processes for four wastewater treatment plants ranged from 83.7% to 96.3%. Application of different tertiary treatment processes (coagulation/flocculation, membrane related technology and disinfection) enhanced microplastics removal to achieve overall removal rate of 92.3%-96.7%. The removed microplastics from the wastewater treatment plants were mainly transferred to sludge (226.1 ± 95.7-896.0 ± 144.0 items/g dry weight). The biological treatment unit played an important role in microplastics removal with rates varying between 86.9%-95.2%, while tertiary treatment reduced daily microplastics emission 1.4 × 108-2.3 × 108 items/day. This study suggests that proper selection of wastewater treatment unit could significantly reduce the emission number of microplastics, which supports an efficient control strategy of microplastics in wastewater treatment plants.

Injectable thermo-sensitive and wide-crack self-healing hydrogel loaded with antibacterial anti-inflammatory dipotassium glycyrrhizate for full-thickness skin wound repair.

Severe skin injuries are hard to repair and susceptible to bacterial infection. Development of a versatile antimicrobial anti-inflammatory hydrogel dressing that eliminates concern over antibiotic resistance is urgently needed but remains an elusive goal. Our research, described herein, the design and fabrication of a new family of supramolecular hydrogels based on hydroxypropyl chitosan (HPCS) and poly(N-isopropylacrylamide) (PNIPAM) may prove to be that goal. Employing the reversible cross-linking by ß-cyclodextrin (ß-CD) and adamantyl (AD) pre-assembly, the hydrogels can be formed in a facile one-pot method. Additionally, the structure and performance of the hydrogels can be controlled by a simple adjustment of the AD content. The obtained hydrogels exhibit an abundance of desired properties; they are injectable, thermosensitive, highly ductile, self-healable (will self-heal recurring damage to the hydrogel bandage of up to several millimeters wide), biocompatible, and have antimicrobial activity against Staphylococcus aureus when infused with dipotassium glycyrrhizinate (DG). Using a mouse full-thickness skin defect model, in vivo wound healing evaluations revealed that the DG-loaded hydrogels (HP-3/DG10) applied to the wound resulted in rapid wound closure. The hydrogels promoted efficient tissue remolding, collagen deposition, decreased inflammation and performed better than the control groups of commercial TegadermTM film and 3M dressing. Given their multifunctionality and in vivo efficacy, the DG-loaded HP hydrogels hold great potential as a wound dressing for full-thickness skin repair. STATEMENT OF SIGNIFICANCE: Injectable hydrogels are receiving increasing attention as an ideal wound dressing. To the best of our knowledge, however, injectable and wide-crack self-healing hydrogel dressings have been hardly studied. A versatile antimicrobial hydrogel without drug resistance or cytotoxicity is also highly required. Therefore, in the present study, we constructed injectable thermosensitive and wide-crack self-healing hydrogels with antibacterial and anti-inflammatory properties. These hydrogels were developed through novel strategies of the wide-crack self-healing design and the loading of the bioactive antibacterial and anti-inflammatory agent dipotassium glycyrrhizinate. The simple preparation method and multifunctionality of the studied hydrogel composites may provide important insights for the development of future biomaterials for wound dressings and other biomedical applications.

Human activities affect the multidecadal microplastic deposition records in a subtropical urban lake, China.

Microplastic deposition in subtropical lakes and the influences of human activities remain to be deeply and fully understood. Owing to the intensification of urban construction and population growth, urban lakes serving as significant freshwater resources for sustainable development of the regional economy are becoming degraded, especially due to microplastic pollution. To understand the deposition characteristics of microplastics in lake sediments from the China's subtropical city, six sediment core samples were collected from Xinghu Lake of Guangdong Province. Here, we analyzed the morphological characteristics of microplastics from the perspective of microstructure, and investigated the temporal and spatial distribution patterns of microplastics on the macroscopic scale. The deposition characteristics of microplastics in the past 64 years and the influence of socio-economic factors on the accumulation of microplastics were further clarified through the isotope composition of cesium-137 and lead-210 in the subtropical urban area with intense human activities. The results showed that the microplastic concentration of sediment cores in Xinghu Lake was 523 ± 140 particles/kg. The average sizes of microplastics in the five sub-lakes (i.e., Bohai, Zhongxin, Li, Qinglian, and Xiannü Lakes) of Xinghu Lake were 668, 642, 727, 708 and 646 µm, respectively. There were 25 polymers in sediment cores of Xinghu Lake. Rayon, polypropylene, polyethylene terephthalate and polypropylene-polyethylene copolymer were the main types, and the microplastics have the aging phenomenon or mechanical abrasion. The average deposition rates of sediment and microplastics were 0.6 cm/a and 106 particles/(kg·a) in Xinghu Lake, respectively. Meanwhile, the urban expansion and economic growth, as indicated by the increase in the urban area, population and gross domestic product, all played an essential role in the accelerated accumulation of microplastics in sediment cores of Xinghu Lake.

Release of the additive metals from 3 commonly used plastics during the degradation under the treatment of UV irradiation.

Additive metals are continuously released into the environment during the photo-degradation of plastics into microplastics, but this phenomenon has not been reported by many studies. Herein, we investigated the surface morphology changes along with the release of additive metals (Cr, Mn, Fe, Co, Cu, Zn, and Pb) during the degradation of three types of plastics, i.e., polypropylene (PP), polyethylene terephthalate (PET) and polyvinyl chloride (PVC), under UV light irradiation. FTIR results showed that 168 days of UV-irradiation led to the primary degradation of each plastic sample. The metal release could be found after 70 days UV-irradiation. The rate of metal release for the three plastics showed the following order: PP > PET ≈ PVC. In addition, the distribution and concentrations of the metals in the plastic could influence the release characteristics of each metal. Low release rate of Fe symbolized by the total metal release in the range of 4.28 ~10.27% as evident from the results of the primary degradation experiment, indicated the release of Fe occurring in the late stage of the plastic degradation or even in the microplastics-formation stage. As for the release of Co from PP, it was far lower than that of the other elements (0.35%), showing the same release characteristics as that of Fe. On the contrary, the release ratio of Pb from PP was 78.89% and was mainly concentrated in the early stage of the plastic degradation. The results help understanding the release behavior of the additive metals during the degradation of typical plastics under ultraviolet light irradiation.

Low level of microplastic contamination in wild fish from an urban estuary.

Microplastic accumulation in estuarine environments is considered the dominant input of land-based plastics into the oceans. In this study, the level of microplastic contamination was evaluated in 26 species of wild fish from the Pearl River Estuary, South China. Results showed that microplastics abundance ranged from 0.17 items individual-1 (Boleophthalmus pectinirostris & Acanthogobius flavimanus) to 1.33 items individual-1 (Plectorhynchus cinctus) among different species. The distribution of microplastic abundance in the gills and gastrointestinal tracts was not significantly different. Microplastics in gills are strongly related to the filtration area of gills in 15 fish species. Fibers were the dominant shapes accounting for 93.45% of the total shapes. The majority of microplastics were <3 mm in size. The most common polymer composition was polyethylene terephthalate (38.2%) and the most common color was black (30.36%). The findings of this study provide baseline data for microplastic contamination in wild fish from an urban estuary.

How biofilms affect the uptake and fate of hydrophobic organic compounds (HOCs) in microplastic: Insights from an In situ study of Xiangshan Bay, China.

Microplastic (MP) has been identified as an emerging vector that transports hydrophobic organic compounds (HOCs) across aquatic environments due to its hydrophobic surfaces and small size. However, it is also recognized that environmental factors affect MP's chemical vector effects and that attached biofilms could play a major role, although the specific mechanisms remain unclear. To explore this issue, an in situ experiment was conducted at Xiangshan Bay of southeastern China, and dynamics of HOCs (i.e., polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs)) and bacterial communities related to the model MP (i.e., PE fibers) were analyzed and compared. Through bacterial characterizations including the 16S rRNA approach, higher summer temperatures (31.4 ± 1.07 °C) were found to promote colonizing bacterial assemblages with larger biomasses, higher activity and more degrading bacteria than winter temperatures (13.3 ± 2.49 °C). Consequently, some sorbed pollutants underwent significant decline in the summer, and this decline was particularly the case for PAHs with low (2-3 rings) and median (4 rings) molecular weights such as phenanthrene (59.4 ± 1.6%), chrysene (70.6 ± 4.2%), fluoranthene (77.1 ± 13.3%) and benz[a]anthracene (71.5 ± 11.0%). In our winter test, however, most pollutants underwent a consistent increase throughout the 8-week exposure period. Moreover, more biorefractory pollutants including PCBs and high molecular weight (5-6 rings) PAHs accumulated regardless of bacterial characteristics. Two putative PAH-degrading bacteria appeared with high relative abundances during the summer test, i.e., family Rhodobacteraceae (18.6 ± 0.5%) and genus Sphingomicrobium (22.4 ± 3.6%), associated with drastic decreases in low (45.2 ± 0.4%) and median (66.0 ± 2.5%) molecular weight PAHs, respectively. Bacterial degradation effects of biofilms on PAHs are also supported by the correlative dynamics of salicylic acid, an important degradation intermediate of PAHs. The results of this study indicate that MP's HOC vector effects are essentially determined by interactions between attached pollutants and microbial assemblages, which are further related to bacterial activity and pollutant features. Further studies of biofilm effects on MP toxicity and on the metabolic pathways of MP-attached HOCs are required.

A chromosome 1q22 microdeletion including ASH1L is associated with intellectual disability in a Chinese family.

BACKGROUND: Copy number variants (CNVs) associated with developmental delay and intellectual disability (DD/ID) continue to be identified in patients. This article reports identification of a chromosome 1q22 microdeletion as the genetic cause in a Chinese family affected by ID. CASE PRESENTATION: The proband was a 19-year-old pregnant woman referred for genetic counseling and prenatal diagnosis at 18 weeks of gestation. She had severe ID with basically normal stature (height 154 cm [0 SD], weight 61 kg [- 0.2 SD], and head circumference 54 cm [- 1.12 SD]). Her distinctive facial features included a prominent forehead; flat face; flat nasal bridge and a short upturned nose; thin lips; and small ears. The proband's father was reported to have low intelligence, whereas her mother was of normal intelligence but with scoliosis. Chromosome microarray analysis (CMA) reveals that the proband, her father and the fetus all carry a 1q22 microdeletion of 936.3 Kb (arr[GRCh37] 1q22 (155016052_155952375)×1), which was not observed in her mother and paternal grandparents and uncles, suggesting a de novo mutation in the proband's father. The microdeletion involves 24 OMIM genes including ASH1L (also known as KMT2H and encoding a histone lysine methyltransferase). Of note, haploinsufficiency of ASH1L has been shown to be associated with neurodevelopmental disorders. Based on the inheritance of the detected CNV in the pedigree and similar CNVs associated with ID in public databases (Decipher, DGV and ClinVar) and literature, the detected CNV is considered as pathogenic. The family chose to terminate the pregnancy. CONCLUSIONS: The identified 1q22 microdeletion including ASH1L is pathogenic and associated with ID. This case broadens the spectrum of ID-related CNVs and may be useful as a reference for clinicians.

Microplastics in mangrove sediments of the Pearl River Estuary, South China: Correlation with halogenated flame retardants' levels.

Marine microplastic pollution of intertidal mangrove ecosystem is a matter of concern. However, the relationship between microplastic distribution and other pollutants such as halogenated flame retardants (HFRs) is unknown. In this study, forty-eight sediment samples were collected from three mangrove wetlands of the Pearl River Estuary (PRE), South China to investigate the distribution of microplastic and discuss the possible relationship between HFRs and microplastic abundance in mangrove sediments. The abundance of microplastic in mangrove sediments from the PRE ranged from 100 to 7900 items·kg-1 dry weight (dw), with an average of 851 ± 177 items·kg-1 dw, which was at a relatively higher level compared to other regions worldwide. The highest abundance of microplastic was observed in Shenzhen mangrove sediments. The abundance of microplastic was significantly and positively correlated with population density and gross domestic product of the PRE. The microplastics with size <500 µm were predominant in mangrove sediments, accounting for a proportion of 69.4% in all microplastic samples. Polypropylene-polyethylene copolymer, green/black, and fibers/fragments were the dominant type, color and shape in all microplastic samples, respectively. The correlation between HFRs and microplastic abundance demonstrated that polybrominated diphenyl ethers, decabromodiphenyl ethane, 1,2-bis(2,4,6-tribromophenoxy)ethane and hexabromocyclododecane may have the same pollution source as microplastics.

Correction to: Characteristic of microplastics in the atmospheric fallout from Dongguan City, China: preliminary research and first evidence.

Unfortunately, the original version of this article contained two mistakes.

Internal Biomechanical Study of a 70-Year-Old Female Human Lumbar Bi-Segment Finite Element Model and Comparison with a Middle-Aged Male Model.

The main purpose of this article is to study the biomechanics of spine tissue in elderly female. In this study, the L3-L5 lumbar bi-segmental finite element model for elderly female was obtained from the Advanced Human Modeling Laboratory of the Bioengineering Center at Wayne State University. The effects of flexion and extension on bone geometry, distribution of ligament fibers, location of nucleus, and changes in intervertebral disc height were studied by comparing the results obtained before and after the update of older female and middle-aged male models. For the purpose of comparing the calculated range of motion (ROM) with the experimental data, additional calculations for axial rotation and lateral bending were performed. The study found that the parameters of the model affected the deformation of the disc herniation, ligament and intervertebral disc, and the axial force carrying capacity of the model. The three predicted ROMs are usually similar to the experimental results. Only the older female model has a slightly larger ROM. Therefore, older women are more vulnerable to lumbar spine injuries than men.

The uptake of microfibers by freshwater Asian clams (Corbicula fluminea) varies based upon physicochemical properties.

Microplastic is an umbrella term that covers particles with various physical and chemical properties. However, microplastics with a consistent shape, polymer type and size are generally used in exposure studies (e.g., spherical polyethylene or polystyrene beads 1-100 µm in size). In the present study, we exposed freshwater Asian clams (Corbicula fluminea) to microfibers with different physicochemical properties at concentrations of 100 and 1000 fibers/L. The first experiment in this study exposed clams to microfibers made from six different polymers, demonstrating that Asian clams uptake more polyester (PET) (4.1 items/g) relevant to other polymers. The next experiment exposed clams to PET fibers of different size classes, demonstrating that uptake in the size range 100-250 µm (1.7 items/g) was greater than other size classes. These results suggest that physicochemical properties such as polymer and size play important roles in the uptake of microfibers by organisms. Thus, we strongly suggest that the properties of microplastics used in future laboratory exposure experiments be considered, with the aim of being "environmentally relevant", i.e., similar to what is found in nature.

Microplastics and associated PAHs in surface water from the Feilaixia Reservoir in the Beijiang River, China.

Microplastics have been a prevalent and persistent contamination problem in the global aquatic environment. In particular, microplastics that can adsorb persistent organic pollutants (POPs) and therefore transfer these POPs to organisms in the aquatic environment have received much attention. In this study, an investigation of microplastics in the surface water of the Feilaixia Reservoir (Guangdong Province, China), which is an important part of people's daily lives in Guangdong Province was carried out, mainly focusing on the characteristics and spatial distribution of microplastics, as well as microplastics and their adsorded PAHs in the surface water of the Feilaixia Reservoir were investigated. The average abundance of microplastics in the surface water of the Feilaixia Reservoir was 0.56 ±â€¯0.45 items/m3. Six kinds of polymers, including polyethylene (PE), polypropylene (PP), polystyrene (PS), expanded polystyrene (EPS), polyvinyl chloride (PVC) and polyethylene terephthalate (PET), were identified, among which PP (52.31%) and PE (27.39%) were the major compositions. Four shapes of microplastics, i.e., foams, films, fragments and fibers were found, and films (37.78%) being the main shape. The most common typical size of the plastic particles ranged from 0.6 to 2 mm (41.36%). The total concentration of the sixteen PAHs carried on the EPS, PE and PP microplastics ranged from 282.4 to 427.3 ng/g; chrysene, benzo [ghi] perylene, and phenanthrene were abundant in the samples, at concentrations of 39.5-89.6 ng/g, 34.6-56.8 ng/g and 25.6-45.6 ng/g, respectively. Based on the ratios of the PAH isomers (Flut/Py < 1 and Phe/Ant >10), it was speculated that the source of the PAHs may be derived from the imperfect combustion of fossil fuels.

Occurrence and distribution of microplastics in an urban river: A case study in the Pearl River along Guangzhou City, China.

Microplastics, as emerging contaminants in the global environment, have become a cause for concern for both academics and the public. The present understanding of microplastic pollution is primarily focused on marine environments, and less attention has been given to freshwater environments, in particular, to urban rivers. In this study, microplastics were sampled from surface water and sediments in 14 sites located in the lower course of the Pearl River. These sampling sites are located along Guangzhou of South China, with built-up areas being the dominant land use. The abundances of microplastics in surface water and sediments ranged from 379 to 7924 items·m-3 and 80 to 9597 items·kg-1, respectively. Polyethylene and polypropylene were the common types of microplastics, together accounting for 64.3% and 73.8% of surface water and sediment samples, respectively. Fibers were the dominant microplastic shapes in both water and sediment samples. The abundances of microplastics varied in surface water and sediments with each site, which might be affected by multiple factors. Our results indicated that wastewater treatment plants (WWTP) could reduce microplastics from municipal sewage which was finally discharged into the Pearl River along Guangzhou.