Dominant Size Range Research Articles

Coagulation of Wastewater Containing Polyethylene Terephthalate (PET) Microplastics by Using Ferric Chloride, Aluminum Sulfate and Aluminum Chlorohydrate: A Comparative Study

This study investigated the efficacy of different coagulants, namely ferric chloride and aluminum sulfate at a concentration of 1.95 g/L, and aluminum chlorohydrate at a concentration of 2.1 g/L, in removing microplastics from plastic recycling facility wastewater under different pH conditions. The results showed that the presence of microplastics in wastewater was 76% in the form of fragments, followed by films and fibers in smaller amounts. The size of these microplastics varies, with a dominant size range of 251-500 μm. At pH 6, ferric chloride and aluminum sulfate were able to remove 75% and 90% of the microplastic abundance, respectively, by adding a dose of 1.95 g/L. However, the highest removal efficiency was obtained by adding a dose of 2.1 g/L Aluminium chlorohydrate at pH 8. These findings underscore the importance of selecting suitable coagulants and optimizing treatment operational conditions based on the type and size distribution of microplastics present in the wastewater system.

Bioaccumulation of microplastics in the edible tissues of fish collected from urban lakes of Bangladesh: a potential exposure to public health.

Microplastic (MP) pollution is an emerging environmental problem, due to its universal dispersion. In the present study, we determined the MP pollution in water, sediment, and fish samples of three different urban lakes of Bangladesh to assess the bioaccumulation of MPs from the lake environment to fish's edible (flesh) and inedible tissue (gut), ecological risk and consequent human exposure to MPs by fish consumption. A total of forty-three fishes were collected from Jahangirnagar Co-Operative Housing Society (JCHS), Dhanmondi Lake (DL), and Saturia Thana Lake (MST). The average MP concentration in sediment and water of the lakes is 7588 ± 4353 MPs/kg dry weights; 142 ± 22 MPs/L, respectively. MPs were identified in the edible (2.8-20.2 MPs/g) and inedible (2.27-20.93 MPs/g) tissue of all fish species. The highest number of MPs was observed in the flesh of Labeo bata of the JCHS Lake and in the gut of Catla catla of DL. The most dominant shape of MPs was fiber and fragment, 0.1-0.4 mm was the dominant size range, and blue, purple, and transparent were the dominant colors. The presence of six polymer types was revealed by FT-IR analysis, which were polystyrene, polypropylene, nitrile, ethylene vinyl acetate, high-density polyethylene, and nylon. The concentration of MPs in fish is found to increase with the increment in body weight. The bioconcentration factor (BCF) analysis reveals that among all the fish species, Labeo bata and Oreochromis mossambicus accumulate the highest number of MPs from the lake environment. The pollution load index of MPs indicates that the sampling sites were within hazard levels III-IV. Estimated annual intake reveals that humans will be exposed to the highest number of MPs if they consume the flesh of Labeo bata of DL and JCHS Lake.

Airborne Microplastics in Indoor and Outdoor Environments of a Developing Country in South Asia: Abundance, Distribution, Morphology, and Possible Sources.

Airborne microplastics (AMPs) have been reported in indoor and outdoor air in high-income countries and are expected to be a significant contributor to daily microplastic (MP) exposure for human beings. To date, there are only a handful of studies in lower-middle-income countries. In this study, AMPs from 5000 to 50 μm were sampled across selected areas of Sri Lanka using an active sampling technique. Suspected AMPs were further characterized using Fourier transform infrared spectroscopy. MP concentrations were higher indoors compared to outdoor air (0.13-0.93, compared to 0.00-0.23 particles/m3, respectively). The types of indoor MPs were related to indoor-generating sources, and the occupant's lifestyles. The highest outdoor MP abundance was found near an industrial zone, followed by urban and inland locations in high-density areas. The dominant size range of MPs was 100-300 μm, and the only shapes observed indoors and outdoors were fibers (98%) and fragments. Polyethylene terephthalate was the most prominent MP type, followed by polyester, indicating that textile fibers could be the major source of these AMPs. This study provides the first report on AMPs in Sri Lanka. Considering population growth and industrialization, further research should evaluate possible trends and health risks upon inhalation.

Microplastics in commercial seafood: Pleoticus muelleri as a case study in an estuarine environment highly affected by human pressure (Southwestern Atlantic).

Plastic pollution in seafood has become a worldwide safety concern due to its possible harm to humans. This is the first study which has investigated the length-weight relationship, growth patterns and condition factor, together with the concentrations of microplastics (MPs) and mesoplastics (MesoPs) in Pleoticus muelleri from the Bahia Blanca Estuary (BBE), Argentina. Forty-nine individuals were collected from three sampling stations in the BBE, and each abdominal muscle with the gastrointestinal tract was analyzed. P. muelleri showed an isometric growth pattern (b = 3.0054) with values of K similar among the individuals collected (ranged between 0.80 and 0.91), considering them in good condition compared to other crustacean species around the world. 96% of shrimp presented transparent or black synthetic fibers as prevalent types, with an abundance average of (3.0 ± 2.90) MPs/g w. w. And (0.053 ± 0.16) MesoPs/g w. w. as well as a dominant size range of 0.5–1.5 mm, in accordance with recent studies in the same area. The linear regression analysis showed that K was independent of the concentration of MPs ingested by P. muelleri, with R2 ranging between 0.024 and 0.194 indicating that MPs contamination does not affect the nutritional condition of shrimp. SEM/EDX detected the presence of elements like C, O, K, and Mg, tissue residues and fractures on the surface of the analyzed fibers. FTIR confirmed different types of polymers in shrimp related to textile fabrics probably from untreated sewage discharges from nearby cities. The results of this research provide useful information for a better understanding of MPs contamination in seafood, suggesting P. muelleri as a suitable species for monitoring MPs in estuarine ecosystems. Likewise, more research is required to know the effects of MPs on food safety in humans.

Microplastic pollution in oyster bed ecosystems: An assessment of the northern shores of the United Arab Emirates

Microplastics pollution in oyster bed ecosystems was investigated in this study. Microplastics in both sediments and oysters from five sites collected along the coast of the United Arab Emirates (UAE) oyster bed ecosystem were assessed for abundance, as well as shape, size, color, and composition. The mean abundance in the sediment samples was 191.7 ± 95.5 MP/Kg of d.w., while the mean abundance in the oyster samples was 101.2 ± 93.8 MP/Kg of sample. In general, 100% of the sediment samples and 51% of the oysters showed the presence of microplastics, yet no correlation patterns between sediment and oysters were seen in the abundance of microplastics. The major shape of microplastics found in all the samples were fibers, accounting for 93 % in all the sites; while the most occurring color was black, accounting for 53% in both the sediment and oyster samples. The most dominant size range was 1.0-2.0mm, which accounted for 34% in both the sediment and oyster samples. This is the first study in the region investigating the presence of microplastics in oyster beds. Considering the ubiquitous presence of microplastics in the sediments of the oyster beds in this study, their sources should be investigated and managed further as they can pose a potential threat to the marine ecosystem.

An examination of the occurrence and potential risks of microplastics across various shellfish

The ingestion of microplastics by shellfish pose a potential health risk for human via seafood consumption. This study investigated and compared the contamination levels and potential human health risks of microplastics in the digestive system of commercial shellfish from North (Qingdao) and South (Xiamen) China. Microplastics were detected in 70%–100% of shellfish samples from Qingdao and 70%–90% of shellfish samples from Xiamen, with abundances ranging from 1.2 to 4.1 items/individual (or 0.8–4.4 items/g, wet weight of digestive system) in shellfish from Qingdao and 1.3–6.0 items/individual (or 2.1–4.0 items/g) in shellfish from Xiamen. The microplastic composition was dominated by rayon and tended to be fibrous in shape, and white, black, and transparent in color. Microplastics <500 μm were the dominant size range, in which the size range of 100–200 μm was the most abundant size. Features of microplastics in the water-dwelling shellfish were different from those of the sediment-dwelling shellfish, and the microplastic features in the shellfish correlated with the sampling region, shellfish length, total wet body weight, and wet weight of the digestive system. Risk assessment results revealed that the potential human health risk posed by microplastics from the digestive system of commercial shellfish was higher in Qingdao than Xiamen.

Overview of primary biological aerosol particles from a Chinese boreal forest: Insight into morphology, size, and mixing state at microscopic scale

Biological aerosols play an important role in atmospheric chemistry, clouds, climate, and public health. Here, we studied the morphology and composition of primary biological aerosol particles (PBAPs) collected in the Lesser Khingan Mountain boreal forest of China in summertime using transmission electron microscopy (TEM) and scanning electron microscopy (SEM). C, N, O, P, K, and Si were detected in most of the PBAPs, and P represented a major marker to discriminate the PBAPs. Of all detected particles >100 nm in diameter, 13% by number were identified as PBAPs. We found that one type of PBAPs mostly appeared as similar rod-like shapes with an aspect ratio > 1.5. Size distribution of the rod-like PBAPs displays two typical peaks at 1.4 μm and 3.5 μm, which likely are bacteria and fungal particles. The second most PBAPs were identified as fungal spores with ovoid, sub-globular or elongated shapes with a smooth surface and small protuberances with their dominant size range of 2–5 μm. Moreover, we found some large brochosomal clusters containing hundreds of brochosomes with a size range of 200–700 nm and a shape like a truncated icosahedron. We estimated that mass concentration of PBAPs approximately 1.9 μg m−3 and contributed 47% of the in situ PM2.5–10 mass. The detection frequency and concentration of PBAPs were higher at night than in the daytime, suggesting that the relative humidity dramatically enhanced the PBAPs emissions in the boreal forest. Our study also showed that the fresh PBAPs displayed weak hygroscopicity with a growth factor of ~1.09 at RH = 94%. TEM analysis revealed that about 20% of the rod-like PBAPs were internally mixed with metal, mineral dust, and inorganic salts in the boreal forest air. This work for the first time provides the overview of individual PBAPs from nanoscale to microscale in Chinese boreal forest air.

Synthesis of silver nanoparticles used chemical reduction method by glucose as reducing agent

Silver nanoparticles have been successfully synthesized using a chemical reduction method at room temperature using glucose as a reducing agent, silver nitrate as a source of nitrate, polyvinyl alcohol (PVA) as a stabilizing agent. The purpose of this research was to determine the effect of the mole ratio of reducing agent Glu / Ag and percentage (%) PVA (b/v) in the silver nanoparticle synthesis of the resulted product. Product characterization was analyzed by UV-Vis Spectrophotometers, XRD, and TEM. The Analysis of the UV-Vis spectra showed that the most stable particles were silver nanoparticles used PVA 3% and Glu / Ag. 1: 8 on λmax 415 to 417 nm. TEM’s characterization showed that silver nanoparticles were spherical with a dominant size range of 12,28 nm – 38,45 nm nm. The newly synthesized silver nanoparticles may have a potential for antibacterial applications.

Sunlight-assisted synthesis of colloidal silver nanoparticles using chitosan as reducing agent

The present study we explore an environmentally friendly colloidal silver nanoparticles preparation using chitosan as reducing agent and stabilizer. It develops a new strategy on preparation of silver nanoparticles through the gel phase using sodium hydroxide (NaOH) as accelerator reagent. Sunlight irradiation was employed to assisted reducing process of silver ions to silver nanoparticles. Localized surface plasmon resonance (LSPR) phenomenon of silver nanoparticles was investigated using UV-Vis spectrophotometer. The shape and size of silver particles were analyzed using TEM. The formation of silver nanoparticles was confirmed by the appearance of LSPR absorption peak at 396.0–412.0 nm. The absorption peak of LSPR were affected by NaOH amount, time of sulight irradiation and concentration of AgNO3. The produced silver nanoparticles were spherical with dominant size range of 5 to 8 nm as shown by TEM images. All colloidals were stable without any aggregation for 30 days after preparation.

Plastics and microplastics on recreational beaches in Punta del Este (Uruguay): Unseen critical residents?

Beaches are social-ecological systems that provide several services improving human well-being. However, as one of the major coastal interfaces they are subject to plastic pollution, one of the most significant global environmental threats at present. For the first time for Uruguayan beaches, this study assessed and quantified the accumulation of plastic and microplastic debris on sandy beaches of the major touristic destination Punta del Este during the austral spring of 2013. Aiming to provide valuable information for decision-making, we performed a detailed analysis of plastic debris, their eventual transport pathways to the coast (from land and sea), and the associated persistent pollutants. The results indicated that the smallest size fractions (<20 mm) were the dominant size range, with fragments and resin pellets as types with the highest number of items. PAHs and PCBs were found in plastic debris, and their levels did not differ from baseline values reported for similar locations. The abundance of plastic debris was significantly and positively correlated with both the presence of possible land-based sources (e.g. storm-water drains, beach bars, beach access, car parking, and roads), and dissipative beach conditions. The analysis of coastal currents suggested some potential deposition areas along Punta del Este, and particularly for resin pellets, although modeling was not conclusive. From a local management point of view, the development and use of indices that allow predicting trends in the accumulation of plastic debris would be critically useful. The time dimension (e.g. seasonal) should also be considered for this threat, being crucial for locations such as Uruguay, where the use of beaches increases significantly during the summer. This first diagnosis aims to generate scientific baseline, necessary for improved management of plastic litter on beaches and their watersheds.

Synthesis of Silver-Chitosan Nanocomposites Colloidal by Glucose as Reducing Agent

Silver-chitosan nanocomposites colloidal was successfully performed by chemical reduction method at room temperature using glucose as reducing agent, sodium hydroxide (NaOH) as accelerator reagent, silver nitrate (AgNO3) as metal precursor and chitosan as stabilizing agent. Compared to other synthetic methods, this work is green and simple. The effect of the amount of NaOH, molar ratio of AgNO3 to glucose and AgNO3 concentration towards Localized Surface Plasmon Resonance (LSPR) absorption band of silver nanoparticles was investigated using UV-Vis spectrophotometer. The stability of the colloid was also studied for the first 16 weeks of storage at ambient temperature. The formation of silver nanoparticles was confirmed by the appearance of LSPR absorption peak at 402.4–414.5 nm. It is also shown that the absorption peak of LSPR were affected by NaOH amount, ratio molar AgNO3/glucose and concentration of AgNO3. The produced silver nanoparticles were spherical with dominant size range of 6 to 18 nm as shown by TEM images. All colloidals were stable without any aggregation for 16 weeks after preparation. The newly prepared silver-chitosan nanocomposites colloidal may have potential for antibacterial applications.

A LiDAR study of the effective size of cirrus ice crystals over Chung-Li, Taiwan

In this paper, we estimated the effective size of ice crystals in cirrus clouds using fall velocity derived from LiDAR (light detection and ranging) measurements at Chung-Li (24.58°N, 121.1°E), Taiwan. Nine shapes of the ice crystals, viz. hexagonal plates, hexagonal columns, rimed long columns, crystals with sector-like branches, broad-branched crystals, stellar crystal with broad arms, side planes, bullet rosettes and assemblages of planar poly-crystals of specific dimensions have been analyzed. The results show that the lidar derived most probable mean effective size of ice crystals is 340±180 μm with a dominant size range of 200–300 μm. The lidar derived mean effective size of cirrus crystals are parameterized in terms of cloud mid-height temperature as well as optical depth. The discussed method will be useful to study the most probable effective size distribution of ice crystals in cirrus cloud.

Evolution of desert pavements and the vesicular layer in soils of the Transantarctic Mountains

Compared to mid-latitude deserts, the properties, formation and evolution of desert pavements and the underlying vesicular layer in Antarctica are poorly understood. This study examines the desert pavements and the vesicular layer from seven soil chronosequences in the Transantarctic Mountains that have developed on two contrasting parent materials: sandstone–dolerite and granite–gneiss. The pavement density commonly ranges from 63 to 92% with a median value of 80% and does not vary significantly with time of exposure or parent material composition. The dominant size range of clasts decreases with time of exposure, ranging from 16–64 mm on Holocene and late Quaternary surfaces to 8–16 mm on surfaces of middle Quaternary and older age. The proportion of clasts with ventifaction increases progressively through time from 20% on drifts of Holocene and late Quaternary age to 35% on Miocene-aged drifts. Desert varnish forms rapidly, especially on dolerite clasts, with nearly 100% cover on surfaces of early Quaternary and older age. Macropitting occurs only on clasts that have been exposed since the Miocene. A pavement development index, based on predominant clast-size class, pavement density, and the proportion of clasts with ventifaction, varnish, and pits, readily differentiated pavements according to relative age. From these findings we judge that desert pavements initially form from a surficial concentration of boulders during till deposition followed by a short period of deflation and a longer period of progressive chemical and physical weathering of surface clasts. The vesicular layer that underlies the desert pavement averages 4 cm in thickness and is enriched in silt, which is contributed primarily by weathering rather than eolian deposition. A comparison is made between desert pavement properties in mid-latitude deserts and Antarctic deserts.

Atmospheric dust dispersal analyzed by granulometry of the Misers Gold Event

Granulometric analysis of ejecta from Misers Gold high explosive cratering experiment demonstrates that atmospheric dust dispersal can be evaluated by particle‐size distribution data. From size analyses of the Misers Gold preshot test bed alluvium, ejecta, and sweep‐up materials collected out to 35 crater radii (1227 m), we find that approximately 5.9 × 106 kg (∼11% of the total crater ejecta mass) was depleted from the crater ejecta deposits and likely represents the portion of the cratered mass initially lofted into atmospheric suspension. The dominant size range of this lofted dust was 88 to 2000 μm with a mean diameter by mass of 384 μm,. In addition to the dust lofted in the explosion column, dust in the size range of 100–800 μm was swept up from the ground by the explosive air blast and base surge dominantly between ranges of 10 and 18 crater radii (360 and 650 m from ground zero). This sweep‐up dust was convectively drawn into the column and contributed up to 2% of the total mass of lofted. Based on the measured abundance of coarse (&gt;250 μm diameter) dust particles in the estimated lofted dust, it is likely that about 70% of this lofted mass fell out within about 1 hour, such that the remaining dust cloud mass was ∼1.8 × 106 kg, which is equivalent to a dust lofted per unit blast yield of 0.5 kT/kT or about 4% of the crater ejecta mass. This study supports the hypothesis that if initial distributions can be constrained, the volume of dust lofted into atmospheric suspension from large surface explosions can be estimated from analysis of particle‐size distributions of ejecta deposited near the explosion. This result may have particular applications to study of the atmospheric effects of historic and prehistoric volcanic eruptions.