Microplastic Particle Size Research Articles

Toxicological Effects of Microplastics and Sulfadiazine on the Microalgae Chlamydomonas reinhardtii.

Despite the fact that microplastics (MPs) facilitate the adsorption of environmental organic pollutants and influence their toxicity for organisms, more study is needed on the combination of MPs and antibiotics pollutant effects. In this study, polystyrene MPs (1 and 5 μm) and sulfadiazine (SDZ) were examined separately and in combination on freshwater microalga, Chlamydomonas reinhardtii. The results suggest that both the MPs and SDZ alone and in combination inhibited the growth of microalgae with an increasing concentration of MPs and SDZ (5–200 mg l–1); however, the inhibition rate was reduced by combination. Upon exposure for 7 days, both the MPs and SDZ inhibited algal growth, reduced chlorophyll content, and enhanced superoxide dismutase (SOD) activities, whereas glutathione peroxidase (GSH-Px) activity was elevated only with the exposure of 1 μm MPs. Fluorescence microscopy and scanning electron microscopy also indicated that particle size contributed to the combined toxicity by aggregating MPs with periphery pollutants. Further, the amount of extracellular secretory protein increased in the presence of MPs and SDZ removal ratio decreased when MPs and SDZ coexisted, suggesting that MPs affected SDZ metabolism by microalgae. The particle size of microplastics affected the toxicity of MPs on microalgae and the combined effect of MPs and SDZ could be mitigated by MPs adsorption. These findings provide insight into microalgae responses to the combination of MPs and antibiotics in water ecosystems.

First long-term evidence of microplastic pollution in the deep subtropical Northeast Atlantic

No anthropogenic pollutant is more widespread in the aquatic and terrestrial environment than microplastic; however, there are large knowledge gaps regarding its origin, fate, or temporal variations in the oceans. In this study, we analyzed sediment trap material from the deep subtropical Northeast Atlantic (2000 m) in a long-term record (2003–2015) to assess the role of the deep ocean as a potential sink of microplastics. Microplastic particles were identified in all 110 analyzed samples with flux rates of 1.13–3146.81 items d−1 m−2. Calculated microplastic mass fluxes ranged between 0.10 and 1977.96 μg d−1 m−2, representing up to 8% of the particle flux. Between years, the composition of the different polymers changed significantly, dominated by polyethylene, whose amount was correlated with the lithogenic input. The correlation between polyethylene and the lithogenic fraction was attributed to an air transport pathway from northeast Africa and surrounding regions. The second most abundant polymer detected in our study was polyvinyl chloride, which is not correlated with lithogenic or biogenic particle flux fractions. Instead, we observed seasonality for polyvinyl chloride with recurring high fluxes in winter before the plankton bloom and significantly lower amounts in summer. Other polymers identified were polypropylene, polyethylene terephthalate, and lower numbers of polystyrene and polymethyl methacrylate. The average microplastic particle size for all samples and polymers was 88.44 ± 113.46 μm, with polyethylene and polyvinyl chloride having the highest proportion of small particles (<100 μm). Our findings provide first insights into temporal variations of sinking microplastics, which are crucial for understanding the fate of plastic in the oceans.

Distribution Characteristics and Source Analysis of Microplastics in Urban Freshwater Lakes: A Case Study in Songshan Lake of Dongguan, China

Current studies on microplastic pollution mainly focus on marine systems. However, few studies have investigated microplastics in an urban lake. This research intends to use an urban lake (Songshan Lake) as an example to explore the pollution characteristics of microplastics and use the principal component as well as the heat map analysis to discuss the relationships between different shapes of microplastics. According to this study, the average abundance of microplastics in the surface water and surface sediments of Songshan Lake were, respectively, 2.29 ± 0.98 items/m3 and 244 ± 121 items/kg; thin films were the major microplastics in both media; transparent this type of color has the most microplastic content. The particle size of microplastics was mainly 0.18–0.6 mm (43.3%) in surface water and 1–2 mm (48.3%) in surface sediments. The composition included five polymers: polyethylene (PE), polypropylene (PP), polypropylene–polyethylene copolymer (PP–PE copolymer), polystyrene (PS), and polyvinyl chloride (PVC), among which PE (47%) and PP (36%) were the main components. Principal component analysis (PCA) showed that there was a positive correlation among the four shapes of microplastics: films, fragments, foams, and fibers. The heat map analysis showed that the same category of shape distribution features may be similar for each sampling site.

Adsorption of lead and cadmium by microplastics and their desorption behavior as vectors in the gastrointestinal environment

The behavior of microplastics (MPs) as vectors of environmental contaminants in aquatic systems can change the fate and transport of some toxic substances and promote their diffusion and bioenrichment. Therefore, our study investigated the adsorption of two kinds of metal ions [Pb(II) and Cd(II)] by polypropylene (PP) and polystyrene (PS) in aqueous solution and the desorption of metal ions in the gastrointestinal environment. Our findings indicated that pH, humic acid, and particle size are key factors affecting the adsorption of metal ions on MPs. The adsorption capacity of Pb(II) and Cd(II) on MPs increases as pH increases, and the presence of humic acid significantly inhibits the adsorption of metal ions on MPs. In a simulated gastrointestinal environment, the desorption rates of the two metal ions on MPs were high and controlled by the MP particle size, suggesting a possible toxicological risk for organisms after ingestion of metal-contaminated microplastics.

Polyethylene microplastics adversely affect airway patency

Human exposure to microplastics through inhalation has been widely reported in recent years. There is a paucity of work focusing on the direct effect of accumulation of microplastics in airways and how it may impact the respiratory function. This study aimed to investigate whether the exposure of microplastic would change the contractility of isolated airway smooth muscle tissue. Microplastics were obtained through milling of high-density polyethylene (HDPE) pellets by using a centrifugal mill. To confirm that the milled microplastic particle size range fell within the definition of microplastic, field-emission scanning electron microscope (FESEM) was employed. The milled microplastics particle size ranged from 44.2 µm to 552.4 µm. The organ bath technique was employed to study the direct change of tissue contractility of rat isolated tracheal rings. Tracheal rings were incubated with polyethylene microplastics of different concentrations (0.3 mg/ml to 10 mg/ml) for a minimum of 18 hours in physiological Krebs buffer, followed by the construction of concentration-response curves to a contractile agent, carbachol (muscarinic agonist). Exposure to all concentrations of polyethylene microplastics enhanced the contractile responses of the tissues to carbachol. However, the effect was only statistically significant in tissues incubated at 3 mg/ml and above (p &lt; 0.05). Findings from this study provide preliminary evidence that exposure to polyethylene microplastics adversely affects airway function. Heightened contractile responses of airways mimic the pathophysiological responses in respiratory diseases such as asthma, chronic cough and chronic obstructive pulmonary disease. Further experiments focusing on the possible mechanism of actions of these microplastics affecting the airway tissue function are now needed.

Pollution status of microplastics in the freshwater environment of China: a mini review

In the last few years, the pollution of microplastics in freshwater environments such as rivers, lakes, and reservoirs has aroused widespread concerns. In this review, rich and appropriate data on microplastics, in the freshwater ecosystem of China, was collected. Following this microplastics in surface waters, sediments, and biota, of the freshwater system, were thoroughly analyzed. The results show that microplastics are widespread in the freshwater environment of China. At the same time, the abundance of microplastics is positively correlated with both intensive human activities and urbanization. The risk index of microplastics is relatively high in the water of Yellow River (654 items/L), Yangtze River (9.20 × 105 items/km2), and Pearl River regions (7571 items/m3). The prevalent shapes of microplastics, in water and sediments, are fragments and fibers. Moreover, the particle size of microplastics is mainly less than 2 mm. In fact, PP and PE are found to be the main polymer types in the freshwater environment of China. Bivalves and freshwater fish are the main research objects of microplastics pollution in China. In parallel to that, the abundance of microplastics, in each aquatic organism, varied from a few to a dozen. Additionally, the characteristics of microplastics in organisms are mainly fibers smaller than 1 mm. Fundamentally, the key two sources of microplastics, in the freshwater environment of China, are wastewater discharge and surface runoff. It is noteworthy that microplastics, in a freshwater environment, does not only cause environmental pollution but harms aquatic organisms, too. Finally, microplastics can reach the human body, through the food chain, causing potential health issues.

Analysis of Microplastic Particle Transmission

The progressive increase in the mass of microplastics in the ecosystem obliges us to urgently define measures to reduce its adverse effects, which primarily requires an understanding of the genesis of its presence and the dynamics of expansion through the biosphere. This paper aims to contribute to the understanding of the dynamics of microplastic particle motion, especially in the context of deposition rate with respect to microplastic material density, microplastic particle size and especially with respect to microplastic particle shape (which significantly affects shape resistance forces). For this purpose, an overview of existing works in the field of modeling the motion of microplastics is given, and a numerical model for modeling the transport of microplastic particles in an inhomogeneous fluid velocity field for laminar flow is formed. The proposed model is thus based on a system of two nonlinear ordinary differential equations.

Microplastics particle size affects cloth filter performance

Can the unit process or operation in the drinking water treatment plant remove Microplastics (MPs)? Is an additional unit operation/process needed? This study aims to determine the cloth filters' ability to remove MPs based on the particle size of MPs. The cloth filter can be used as an additional unit operation after a conventional rapid sand filter or as surface filtration in the ultrafiltration process. The cloth filter media was made by 194 μm, 115 μm, and 57.5 μm polyester. The artificial MPs size varied from 210 to 420 μm and > 420 μm. A 194 μm filter pore could remove 41.5% of MPs which particle size >420 μm, while 115 μm and 57.5 μm filters pore could remove 55.5% and 83.7%, respectively. A 194 μm filter pore could remove 34% of MPs which particle size range of 210–420 μm, while 115 μm and 57.5 μm filters pore could remove 52.85% and 85.3%, respectively. Based on tensile strength and elongation, the 194 μm filters pore were better than both 115 μm and 57.5 μm filter pores. However, quality (tensile strength and elongation) had no impact on MPs removal due to its large pore size. Filters which pore sizes 194 μm and 115 μm showed that the MPs size had a significant effect on removal (p < 0.05) on which also be shown by regression coefficient of 34.7% and 15.8%. However, for 57.5 μm pore filter, the MPs size did not affect MPs removal (p-value>0.05) on which also be shown by a low regression coefficient of 1%.

The role of crystallinity and particle morphology on the sorption of dibutyl phthalate on polyethylene microplastics: Implications for the behavior of phthalate plastic additives

The sorption behavior of phthalate additives in plastic and microplastic litter is an important process controlling the exposure, net health risk and ecotoxicity of these co-occurring pollutants. Plastic crystallinity and particle morphology are hypothesized to be important variables for microplastics sorption behavior, but to date there have been few direct studies to explicitly test for the influence of these parameters. To address this, in this study we explored the sorption of dibutyl phthalate (DBP) as a probe molecule to diverse polyethylene microplastics including irregularly-shaped pure polyethylene microplastics (IPPM), black plastic film microplastics (BPFM), white plastic film microplastics (WPFM), and commercial microspheres (CM), which had crystallinities ranging from 17 to 99%. Sorption kinetics for all materials could be well represented with both a pseudo-first-order (R2 = 0.87–0.93) and pseudo-second-order model (R2 = 0.87–0.93). Further, sorption was highly linear in the concentration range of 0.5–10 mg L−1, with no greater performance from a linear sorption model (R2 = 0.96–0.99) than the non-linear Freundlich or Temkin sorption models. The partition coefficient (Kd) of DBP sorption onto IPPM, BPFM, WPFM and CMs were 1974.55 L kg−1, 1483.85 L kg−1, 1477.45 L kg−1 and 509.37 L kg−1, respectively, showing a significant decrease with increasing crystallinity (r2 = 0.98). The particle size of microplastics (27–1000 μm) is, however, an indecisive factor affecting their sorption behavior for DBP in this study. This study provides new insight that crystallinity plays a governing role on the sorption of phthalate from microplastic. This should be considered in future exposure studies and assessments of phthalates from plastics and microplastics.

Vertical microplastic distribution in sediments of Fuhe River estuary to Baiyangdian Wetland in Northern China

Microplastics exist widely in water environment. The microplastic distribution in sediments can better reflect the long-term microplastic pollution, especially the vertical distribution. However, the vertical microplastic distribution in sediments is diverse and unclear. This paper is the first study on vertical microplastic distribution in estuary sediment of Fuhe River, the main upstream river flowing to Baiyangdian Wetland in the northern China. The typical feature of Fuhe River is that the effluent of municipal wastewater treatment plants is its main water source. Microplastics in 15 sampling sites and different depths (0–50 cm) were examined. Results showed that the microplastic content decreased with the increase of sediment depth, and the highest content was 1049 ± 462 items/kg in the topmost sediment layer (0–5 cm). The particle size of microplastics was smaller in deeper sediment layers. The proportion of colored microplastics in deeper sediment layers was larger than that in shallower layers. Polyethylene (PE) and polypropylene (PP) were the main plastic polymer types in all sediment samples. The spatial distribution characteristics of microplastics in sediments were closely related to human activities, and the microplastic content was higher in the areas with more intense human activities. This study is helpful to understand the detailed distribution characteristics of microplastics in typical rivers in the northern China, and can provide guidance for reducing microplastic pollution.

Distribution of microplastics in mulched soil in Xinjiang, China

In order to study the distribution of soil microplastics in the plastic film mulched farmland, the fluidization-centrifugation secondary density flotation method was optimized and improved to obtain the samples. The main components of microplastics were analyzed by Fourier spectrometer, and the surface morphology, porosity, particle size and abundance distribution characteristics of microplastics were studied by electron microscopy. The results showed that plastic mulch is the main source of microplastics. Its morphology mainly consists of fragments, fibers and particles. The size of debris microplastics was larger, with an average of 1.6300 mm, mainly distributed in the 0-300 mm cultivation layer while the size of particle micro plastic was smaller, with an average of 0.1400 mm. The width of fiber microplastic was 5-20 μm, but the length could reach 0.2000-2.0000 mm, with an average particle size of 0.9200 mm. Fiber and granular microplastics could be seen in each soil layer. The surface layer of microplastics has a large number of pores characterized with a length of 50 μm and a width of about 5-10 μm, which might be an easy oxidation site for microplastics. This oxidation is continuous, making microplastics continuously decompose into smaller particles. The abundance of microplastics is negatively correlated with soil depth. The average abundance of microplastics is 161.50±5.20 pieces/100 g in 0-300 mm soil layer, which is their main enrichment area. However, the average abundance of microplastics decreases to 11.20±1.10 pieces/100 g in 400-800 mm soil depth. Moreover, the average particle size of microplastics is also linearly negatively correlated with soil depth. Microplastics with smaller particle size are easier to migrate as they pass through soil pores under the action of water and fertilizer. The research can provide s reference for understanding plastic mulch pollution. Keywords: soil microplastics, plastic pollution, distribution, composition DOI: 10.25165/j.ijabe.20211402.6165 Citation: Hu C, Lu B, Guo W S, Tang X Y, Wang X F, Xue Y H, et al. Distribution of microplastics in mulched soil in Xinjiang, China. Int J Agric & Biol Eng, 2021; 14(2): 196–204.

Distribution characteristics of microplastics in urban rivers of Songjiang District, Shanghai

Plastic products are widely used for their low price, light weight and convenience for carrying. Meanwhile, more and more discarded plastic trashes enter water bodies. They can break down to smaller fragments by physical and chemical factors. Plastic debris whose sizes are smaller than 5 mm can be defined as microplastics. Microplastics can be ingested by organisms that take them as size-similar food. They can be transferred to human body through food chain by bioaccumulation and cause health crisis. Though there are plenty of researches focusing on marine microplastics, little attention is paid to microplastics in urban rivers. The urban rivers are closer to human residents and are largely influenced by human activities. So to understand the status of microplastics in urban rivers is urgent for human health. Shanghai, as an international economic, financial, trade, shipping, science and technology innovation center, is with dense population and strong human activities. Located in the Yangtze River Delta area, Shanghai is in the east of China, and near the Yangtze River Estuary and the East China Sea. Songjiang District is located in the southwest of Shanghai, about 40 km away from the urban area. The main rivers are Huangpu River, Dianpu River and Sijingtang River. The industry, agriculture and tourism are relatively developed in Songjiang District, so the pillar industries are diversified. In order to reveal the distribution and influencing factors of microplastics in urban rivers in Songjiang District, Shanghai, the contents, particle size range, sources and influencing factors of microplastics in four rivers which flow through different functional areas in Songjiang District were studied by means of surface sampling, density suspension separation, optical microscope and Laman spectroscopy. Results showed that the content of microplastics in the four rivers in Songjiang area was 2-5 pieces · m^-3, and the content of microplastics was negatively correlated with the runoff (<italic>R</italic>²=0.81, <italic>P</italic><0.05). The river with slow flow was more likely to hold the microplastics in the water. The particle size of microplastics in the river ranged from 0.5 mm to 5.0 mm, and the particle size was relatively large. Microplastics mainly came from human life plastic waste and plastic packaging in industrial and agricultural production. The research results can provide a reference for the analysis of the current situation of urban river microplastic pollution, and lay a foundation for further prevention and control of urban microplastic pollution.

Distribution and characteristics of microplastics in the basin of Chishui River in Renhuai, China

As an emerging pollutant, microplastics widely exist in rivers all over the world. Due to the differences of economic development, economic structure and population in different regions, the abundance of microplastics in rivers is different. In those areas where agriculture is developed, the content of film microplastics is more, while in densely populated areas, the content of fibrous microplastics is more. Taking Renhuai Basin of Chishui River as the research object, the pollution characteristics and current situation of microplastics in the basin were analyzed, and the contamination risk of microplastics was evaluated. The abundance of microplastics in Renhuai basin of Chishui River ranges from 1.77 to 14.33 items/L. The main forms of microplastics were fibrous (59.4%), white (including transparent) (41.3%) and polychromatic (44.1%). The particle size of microplastics was mainly 500– 1000 μm (63.9%). According to the assessment, the risk of microplastics in the basin is 111.79, which is a secondary risk area. This study can provide a further reference for understanding the pollution characteristics of microplastics in rivers.

Effect of microplastic particle size to the nutrients removal in activated sludge system

Microplastics as emerging environmental pollutants, its effect to the bioprocess of water and wastewater treatment has aroused concern. This study investigated the effects of microplastic polystyrene (PS) particle size to the activated sludge nutrient removal process. The ammonia, nitrite, nitrate and phosphorus removal under various PS particle size during nitrification and denitrification process was tested. The results indicated that with PS particle size 150–300 μm, the ammonia oxidation during nitrification process was inhibited to 71%, 92%, and 80% as compared with the blank reactor, for PS concentration at 0.01 g/L, 0.05 g/L and 0.10 g/L, respectively. The nitrite accumulation during nitrification process was also high at PS particle size 150–300 μm and concentration no less than 0.05 g/L. The nitrate reduction during the denitrification process was all inhibited to 69%–94% as compared with the blank, except for reactor No.4. The phosphate removal during nitrification process was not affected by the existence of microplastics PS, the average removal rate was over 80% after 2 h and over 95% after 3 h, respectively. The microplastics particle size plays important role in affecting the activated sludge nutrient removal process.

Distribution of microplastics in mulched soil in Xinjiang, China

In order to study the distribution of soil microplastics in the plastic film mulched farmland, the fluidization-centrifugation secondary density flotation method was optimized and improved to obtain the samples. The main components of microplastics were analyzed by Fourier spectrometer, and the surface morphology, porosity, particle size and abundance distribution characteristics of microplastics were studied by electron microscopy. The results showed that plastic mulch is the main source of microplastics. Its morphology mainly consists of fragments, fibers and particles. The size of debris microplastics was larger, with an average of 1.6300 mm, mainly distributed in the 0-300 mm cultivation layer while the size of particle micro plastic was smaller, with an average of 0.1400 mm. The width of fiber microplastic was 5-20 μm, but the length could reach 0.2000-2.0000 mm, with an average particle size of 0.9200 mm. Fiber and granular microplastics could be seen in each soil layer. The surface layer of microplastics has a large number of pores characterized with a length of 50 μm and a width of about 5-10 μm, which might be an easy oxidation site for microplastics. This oxidation is continuous, making microplastics continuously decompose into smaller particles. The abundance of microplastics is negatively correlated with soil depth. The average abundance of microplastics is 161.50±5.20 pieces/100 g in 0-300 mm soil layer, which is their main enrichment area. However, the average abundance of microplastics decreases to 11.20±1.10 pieces/100 g in 400-800 mm soil depth. Moreover, the average particle size of microplastics is also linearly negatively correlated with soil depth. Microplastics with smaller particle size are easier to migrate as they pass through soil pores under the action of water and fertilizer. The research can provide s reference for understanding plastic mulch pollution. Keywords: soil microplastics, plastic pollution, distribution, composition DOI: 10.25165/j.ijabe.20211402.6165 Citation: Hu C, Lu B, Guo W S, Tang X Y, Wang X F, Xue Y H, et al. Distribution of microplastics in mulched soil in Xinjiang, China. Int J Agric & Biol Eng, 2021; 14(2): 196–204.

A commonly available and easily assembled device for extraction of bio/non-degradable microplastics from soil by flotation in NaBr solution

Soil microplastic pollution has caused widespread research attention worldwide. It is necessary to efficiently separate microplastic particles from soil matrixes in order to conduct studies of microplastic. And so far, few studies have described the separation and extraction devices of biodegradable microplastic. Here we present a commonly available device for extraction of non-degradable and biodegradable microplastics from soil samples in a NaBr solution based on density flotation. The device has a combined circulation and recovery system for the salt solution, which increases its environmental-friendliness. The accuracy and precision of the device was verified through spike and recovery experiments using three types of biodegradable microplastics (PBS, PBAT, PLA) and four types of non-degradable microplastics (LDPE, PS, PP, PVC), all with different particle sizes, and all microplastics are grinded autonomously, closer to reality. In despite of differences in particle size and density, for both biodegradable and non-degradable microplastics the device exhibited good extraction precision, with recovery rates ranging from 92% to 99.6%, over a wide range of particle densities and sizes. The recovery rates slightly increased with increased polymer density and microplastic particle size.

Occurrence Characteristics and Quality Estimation of Microplastics in Drainage Ditches in Hetao Irrigation District of Inner Mongolia

Microplastic pollution due to land runoff has gained increasing attention as it is closely associated with human beings. In this study, we analyzed the occurrence characteristics of microplastics in drainage channel and main drainage channel in Hetao irrigation district of Inner Mongolia and estimated its quality. Through field sampling, the density separation of suspension method and microscope observation, Fourier infrared spectrum measurement, and proportional flow method, the abundance distribution, shape, color, particle size, and chemical composition of microplastics in the water body and sediment of the drainage channel and main drainage channel in the Hetao irrigation district were identified. The mass of microplastics transported in the main drainage channel was also estimated. The results showed that the value range of microplastic abundance in the water body of the drainage channel and the main drainage channel in Hetao irrigation district was 2880-11200 n ·m-3, and the value range of microplastic abundance in the sediment was 100-292 n ·kg-1. Fiber was the most common microplastic form, occupying 34.98%-70.39% and 42.24%-58.56% in the water and sediment, respectively. The color of microplastics was mainly transparent, which occupied 46.43%-61.51% and 40.41%-57.44% in the water and sediment, respectively. The largest particle size of microplastics was<0.5 mm, accounting for 46.43%-61.51% and 43.27%-54.79% in the water and sediment microplastics, respectively. It was concluded that polyethylene was the most common type (43%), followed by polystyrene (34%) and polypropylene (16%) using Fourier infrared spectroscopy. It was estimated that the main drainage channel in the Hetao irrigation district could transport 116.06 kg of microplastics into Lake Ulansuhai every day, and a serious microplastic pollution effect was generated due to the accumulation of microplastics in Lake Wulangsuhai. This study can provide reference for the pollution of microplastics in Hetao irrigation district of Inner Mongolia.

Investigation of the Presence and Possible Migration from Microplastics of Phthalic Acid Esters and Polycyclic Aromatic Hydrocarbons

The work detailed here examined the presence and possibility of leaching of phthalic acid esters (PAEs) and polycyclic aromatic hydrocarbons (PAHs) from various products in everyday use. Due to the complicated matrix, which is plastic, extraction parameters should be selected separately each time. The properties of both the extractant and the material selected for testing should also be taken into account, which is very difficult in practice. In addition, when designing new methods, it is particularly important to take into account the principles of green chemistry so as not to burden the environment additionally. For this purpose, it is important to know the factors that affect the extraction of impurities. Therefore, the main objective was to assess the impact of selected environmental conditions on the process by which such pollutants in plastics like polyvinyl chloride (PVC), polystyrene (PS), polypropylene (PP) and rubber migrate. Analysis inter alia addressed the impacts of type of plastic, migration time, temperature and microplastic particle size. It proved possible to note the presence in PVC and rubber of both PAEs and PAHs—as substances posing a particular threat to the environment. One of the former is the commonly-used plasticiser di(2-ethylhexyl) phthalate (DEHP), a listed priority hazardous substance under the provisions of Directive 2013/39/EU as regards priority substances in the field of water policy. As monitoring of this substance in the environment indicates amounts that are increasing steadily, the design of effective removal methods needs to start with initial estimates of amounts appearing in the environment over time. Main sources need to be explored, albeit in the certain knowledge that the ubiquitous microplastics are among these, inter alia as influenced by elution mechanisms. An attempt was also made to identify and characterise other auxiliary substances added to plastics as they are being produced. Indeed, chromatograms and GC/MS spectra suggest leaching of many other plastic substances. Relationships between eluted pollutants were also sought.

Determination of microplastic content in seafood: An integrated approach combined with the determination of elemental contaminants

A method for the determination of microplastic (MP) content in seafood is proposed based on the selective digestion of seafood without the degradation of MP. A simple approach was developed using diluted acid with microwave-assisted wet digestion. The following parameters were evaluated: nitric acid concentration (0.5 to 14.4 mol L−1), digestion temperature (180 to 220 °C), irradiation program holding time (10 to 30 min), MP particle size (0.3 to 5 mm), and the seafood mass (0.5 to 2 g). To develop a reliable method for the determination of MP amount, up to 2 g of an in natura seafood sample were spiked with a known amount of MP (100 mg of mixed MP). Suitable conditions were obtained using 1 mol L−1 HNO3 at 200 °C (10 min holding time). Digests were filtered and the plastic content was gravimetrically determined. The heating program was 20 min, which represents a significant reduction in the time normally reported in the literature for MP analysis (from few hours up to 3 days). The proposed method allowed gravimetric determination of eight plastic types (polyethylene terephthalate, polystyrene, expanded polystyrene, polypropylene, high and low density polyethylene, polycarbonate and polyvinyl chloride) with particle size ≥0.3 mm. Up to 2 g of an in natura seafood sample (shark species, acoupa weakfish, tuna fish, trahira, and pink shrimp) were efficiently digested, which opened the possibility of using the proposed digestion method for determining elemental contaminants (Al, As, Ca, Cd, Co, Cr, Cu, Fe, Hg, La, Mg, Mn, Mo, Ni, Pb, and Zn). Thus, as the main feature of the proposed digestion method is the possibility of determining MP and elemental contaminants using the same digestion protocol, saves time and reagents and provides accurate and precise information about different classes of marine pollutants (MP and elemental contaminants).

Bioaccumulation effects of microplastics and heavy metals pollutants in the dominant freshwater fish species in the Longkou entry of Raohe River, Lake Poyang Basin

水体生态环境中的微塑料与重金属污染问题正日益受到热切关注.为探讨微塑料与重金属对水产品的复合生态效应，选择鄱阳湖-饶河段优势淡水鱼为研究对象，对鱼体内微塑料及重金属Cu、Cd、Pb、Zn、Cr等元素的生物累积作用进行分析与评价.结果表明：调查区域水环境中微塑料的丰度范围10~64 items/L，平均值38.56 items/L.8种淡水鱼消化道微塑料丰度范围为1.21~9.11 items/g，平均丰度为5.40 items/g；鳃部丰度范围0.61~5.00 items/g，平均丰度为2.87 items/g；微塑料类型主要有碎片类、纤维类、薄膜类和颗粒类4种，其聚合物成分主要为聚乙烯（PE）、低密度聚乙烯（LDPE）、聚丙烯（PP）和聚苯乙烯（PS）；颜色以透明及彩色为主；微塑料粒径范围为0.01~9.5 mm，粒径>0.5 mm的微塑料所占比例为79.07%，鱼体内与其生存水环境中微塑料的丰度特征（形态、粒径、颜色和聚合物类型组分比例）具有一定相似性.各鱼类对微塑料的累积系数（BAF）平均值为178.29，不同鱼类累积微塑料的能力大小次序为：乌鳢（Channa argus）、黄颡鱼（Pelteobagrus fulvidraco） > 鲦鱼（Hemicculter leuciclus）、草鱼（Ctenopharyngodon idellus）、鲶鱼（Silurus asotus） > 鲤鱼（Cyprinus carpio）、刀鱼（Coilia ectenes）、鲫鱼（Carassius auratus）.鱼体肌肉组织内重金属Cu、Cd、Pb、Zn、Cr的平均含量分别为4.27、0.13、0.28、11.73、0.53 mg/kg，均符合无公害水产品的要求且低于人体消费卫生标准，属于安全食用范围；鱼类对5种不同重金属的累积能力大小次序为Zn > Cu > Cd > Pb > Cr，不同鱼类对不同重金属的累积能力具有差异性.通过扫描电镜（SEM）与能谱分析（EDS）检测到各类型微塑料表面均有上述5种重金属元素，证实微塑料可能成为重金属的附着载体，相关性分析表明微塑料与Cu呈极显著相关，与Cd、Pb均呈显著相关；微塑料的存在一定程度上会增强Cu、Cd与Pb的累积效应，并可能产生复合污染效应.;Pollution of microplastics and heavy metals in aquatic eco-environment is attracting more and more attention. In the present study, in order to explore the bioaccumulation characteristics of microplastics and heavy metals in organisms, we selected eight dominant freshwater fish species in the Lake Poyang and Raohe River as the research materials. The concentrations of heavy metals (i.e. Cu, Cd, Pb, Zn and Cr) and microplastics in the fishes were measured and analyzed. The results indicated that the abundance of microplastics in water environment ranged from 10 to 64 items/L, with an average of 38.56 items/L. The abundance of microplastics in the digestive tract of the eight fish species ranged from 1.21 to 9.11 items/g, with an average of 5.40 items/g, while the abundance of microplastics in gills of fish varied between 0.61 and 5.00 items/g, with a mean of 2.87 items/g. There were four types of microplastics in fishes including debris, fibers, films and pellets. The polymer components were mainly polyethylene (PE), low-density polyethylene (LDPE), polypropylene (PP) and polystyrene (PS) that were mainly transparent and colorful. The particle size of microplastics ranged from 0.01 to 9.50 mm, and 79.07% of the microplastics had particle size>0.5 mm. The abundance characteristics (i.e. types, particle size, color and polymer composition) of microplastics in fishes were similar as those in water environment. The averaged bioaccumulation coefficient of microplastics in fishes was 178.29. The bioaccumulation ability of microplastics in fishes was ordered as follows:Channa argus, Pelteobagrus fulvidraco > Hemicculter leuciclus, Ctenopharyngodon idellus, Silurus asotus > Cyprinus carpio, Coilia ectenes, Carassius auratus. The contents of heavy metals including Cu, Cd, Pb, Zn and Cr in the muscle tissues of fishes were 4.27 mg/kg, 0.13 mg/kg, 0.28 mg/kg, 11.73 mg/kg and 0.53 mg/kg, respectively, which meet the requirements of pollution-free aquatic products and are lower than the health standards for human consumption. The enrichment ability of the fishes to the five heavy metals was ordered as follows:Zn > Cu > Cd > Pb > Cr. Different fish species showed different ability on the accumulation of a specific type of heavy metals, which is closely related to their feeding habits. The five heavy metals were detected on the surface of various microplastics by using Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) methods, suggesting that microplastics may be the attachment carrier of heavy metal pollutants. Correlation analyses showed that the concentration of microplastics in fishes were significantly correlated with that of Cu, Cd and Pb, probably because that the presence of microplastics enhances the cumulative effects of Cu, Cd and Pb, and lead to the compound pollution effects.