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Airborne particulate matter (PM) with an aerodynamic size cutoff of 10 µm (PM10) has been collected using a high volume air sampler at two locations (urban and residential) in the city of Ahvaz, Iran, for sixteen 24-hour periods over four months (late summer to early winter). Microplastics (MPs) in the PM were isolated after sample digestion and were subsequently characterised by established techniques. All MPs sampled (n = 322) were of a fibrous nature, with polyethylene terephthalate, nylon and polypropylene being the dominant polymers and consistent with textiles and fabrics as the principal source. Despite a distinct seasonality (temperature and wind) over the study period, the abundance, size and colour of the fibres exhibited no clear temporal trend, and no clear differences were observed between the two sites. Concentrations of MPs ranged from none detected to about 0.017/m

In the present study, 6 water and 16 sediment samples were collected from Hashilan Wetland (Kermanshah Province, Iran) to specify physio-chemical properties of water and sediment and to evaluate the water pollution load with reference to the water physicochemical parameters. According to the Piper diagram, Ca2+–Mg2+–HCO3− hydrochemical facies is dominant due to calcium carbonate dissolution in the geological formations of the study area. The wetland water had a natural to slightly alkaline pH. Although TDS and EC of the water samples fall under freshwater category, their values were higher downstream of the wetland as a result of stagnant water, low water depth, more evaporation, and impact of agricultural runoff. Based on the water quality index (WQI), all water samples were ‘suitable’ for irrigation purposes, while 50% of the samples were ‘unsuitable’ for drinking. Comprehensive Pollution Index (CPI), and Sodium Adsorption Ratio (SAR) also indicated suitability of the wetland water for irrigation. According to the Wilcox diagram, salinity is higher downstream of the wetland due to introduction of agricultural runoff. It can be concluded that the wetland water could be used for irrigational purposes, but regular monitoring is recommended to promote sustainable use of natural resources and conserve the vulnerable aquatic ecosystem.

Agricultural soils are a secondary source of airborne microplastics (MP) through wind-driven erosion, especially in arid and semi-arid regions. However, this transport pathway has thus far received little scientific attention. In this study, we measured microplastics in both soil and wind-eroded sediment using a portable wind tunnel in two vegetable-growing fields of Fars province, Iran that have been subject to different agricultural practices: plastic mulch (Field 1) and irrigation with wastewater (Field 2).Microplastic concentration in soil ranged from 0.04 MP g-1 to 0.83 MP g-1 in Field 1 and from 0.20 MP g-1 to about 1.1 MP g-1 in Field 2. Fibres represented the dominant shape of MPs, but spherules, presumably from wastewater, also made a significant contribution to MPs in Field 2. Analysis of samples by Raman spectroscopy and scanning electron microscopy (SEM) revealed that polyethylene terephthalate (PET) and nylon were the most abundant polymers and that MPs exhibited varying degrees of weathering. Concentrations of MPs in this study are within the range reported previously for agricultural soils.Results of the wind tunnel revealed threshold velocities for wind erosion of 7 and 12 m s-1 and MP erosion rates of 0.4 and 1.1 MP m-2 s-1 for Fields 1 and 2, respectively. MP concentrations in wind-eroded sediment were considerably higher than the agricultural soil samples and were significantly higher (p < 0.05) in Field 2 (mean and median of 45.26 MP g-1 and 42.89 MP g-1, respectively) than in Field 1 (mean and median of 9.08 MP g-1 and 11.35 MP g-1, respectively). This revealed enrichment of MP in wind-eroded sediment compared to the original soil. Erosion rates are significantly higher than published depositional rates of MPs and suggest that agricultural soils act as both a temporary sink and dynamic secondary source of MPs that should be considered in atmospheric transport models and risk assessments.

Soils are an important source of microplastics (MPs) to the atmosphere but the fluxes and mechanisms involved in MPs entrainment are not well understood. In the present study, a series of horizontally aligned sediment traps have been deployed at different heights within 1 m above the ground for a two-month period at various locations in an arid region (Sarakhs, Iran). MPs were isolated from sediments and were quantified and characterised according to size, colour, shape and polymer composition by established techniques. Most MPs were nylon > polypropylene > polystyrene > polyethylene terephthalate. The distributions of sediment mass (range

The vast amount of plastic waste emitted into the environment is of increasing concern because there is mounting evidence for various toxic effects of microplastics on living organisms. In particular, despite freshwater ecosystems are essential sources of water supply, they have been less investigated than marine ecosystems for microplastic pollution. Here, we review 150 freshwater studies for techniques used to separating microplastics from water and sediments. We compare major chemicals utilized in digestion and density separation steps. Sodium chloride is the most prevalent salt used in separating microplastics from freshwater environments. Hydrogen peroxide and Fenton’s reagent are most frequently used in digestion of organic materials.

Plastics have overwhelmingly been employed in every sector of human life, ranging from the cosmetics and food industry to transportation and electronics. It resulted in emerging plastic pollution worldwide, which poses serious threats to the natural ecosystem and human health. This mini-review highlights human exposure to micro(nano)plastics in the environment and evaluates bioplastics as a health/environment safer option.

Although airborne urban particles are a concern for air quality and human health, little information exists on the levels and characteristics of microplastics (MPs) and microrubbers (MRs) in this setting. In the present study, MPs and MRs are quantified and characterised in road dusts and accumulations captured passively (and up to elevations of 177 cm above road level) in the steps of utility poles at 18 locations throughout the city of Shiraz, southwest Iran. Dust accumulation rates were greatest at road level (median = 45 g m

The discovery of atmospheric micro(nano)plastic transport and ocean-atmosphere exchange points to a highly complex marine plastic cycle, with negative implications for human and ecosystem health. Yet, observations are currently limited. In this Perspective, we quantify the processes and fluxes of the marine-atmospheric micro(nano)plastic cycle, with the aim of highlighting the remaining unknowns in atmospheric micro(nano)plastic transport. Between 0.013 and 25 million metric tons per year of micro(nano)plastics are potentially being transported within the marine atmosphere and deposited in the oceans. However, the high uncertainty in these marine-atmospheric fluxes is related to data limitations and a lack of study intercomparability. To address the uncertainties and remaining knowledge gaps in the marine-atmospheric micro(nano)plastic cycle, we propose a future global marine-atmospheric micro(nano)plastic observation strategy, incorporating novel sampling methods and the creation of a comparable, harmonized and global data set. Together with long-term observations and intensive investigations, this strategy will help to define the trends in marine-atmospheric pollution and any responses to future policy and management actions. Atmospheric transport of microplastics could be a major source of plastic pollution to the ocean, yet observations currently remain limited. This Perspective quantifies the known budgets of the marine-atmospheric micro(nano)plastic cycle and proposes a future global observation strategy.

Although microplastics (MPs) are ubiquitous environmental contaminants, little is known about their occurrence and behavior in the terrestrial setting. In this study, MPs have been isolated from soils collected from various geomorphological features (yardangs, sand dunes, moving sands, seasonal lakes) of the Kavir and Lut Deserts on the Iranian plateau. The number of MPs identified in 300 g samples ranged from zero (not detected) in several yardang tops to 25 on some yardang hillsides, with an overall average abundance of about 0.02 MP g-1. The majority of MPs were of a fibrous nature with a size distribution (≤100 μm to ≥1000 μm) skewed toward the lower end, and analysis of a selection of particles by μ-Raman spectroscopy showed that polyethylene terephthalate and Nylon (polyamide) were the principal polymers. Scanning electron microscopy revealed intense degradation of some particles but limited weathering of others. With little evidence of meso- and macroplastics in the deserts, it appears that the majority of MPs are brought into these environments from distant sources via the wind, with smaller, seasonal contributions from runoff associated with the adjacent mountains. It is proposed that some windborne MPs are transported through the deserts relatively rapidly, while others are subject to internal recycling and significant photo-oxidation and mechanical weathering.

Airborne microplastic is a new area of research in the microplastic domain. Recently, microplastic presence was reported in areas remote from any urban, industrial, and agricultural sources. This reveals the role of the atmosphere in the transport and dispersion of microplastics. Dust storms can shift significant quantities of soil particles and associated microplastics, especially in arid and semi-arid regions. This study reports the presence, characteristics, and potential sources of microplastics in a severe dust storm in Shiraz, southern Iran, in May 2018. Using the method adopted by Bergmann et al. (2019), 22 dust samples were collected from parked cars directly after the event. Dust samples were analyzed for microplastic using the density extraction method and Raman Spectroscopy. The hybrid Lagrangian and Eulerian model of HYSPLIT (Hybrid Single-Particle Lagrangian Integrated Trajectory) was used for back trajectory analysis in order to determine the origin of air masses.Results showed that MP concentrations ranged from 0.04 to 1.06 particles per g of dust. In total, 485 microplastics were detected in all dust samples. The main shape of microplastics was fibrous and polymer makeup was dominated by nylon, polypropylene, and polyethylene terephthalate. Scanning Electron Microscope (SEM) images revealed different degrees of weathering in microplastics. Results of modeling together with the geochemical evidence suggested that the Arabian Peninsula constitutes the principal distal and transboundary source. Results also estimated that about 2 * 1012 microplastics could be transported by such a dust event. According to the literature on MP concentrations in urban dust and remote arid soils, it was estimated that between 0.1 and 5% of MPs in the dust samples were originated from local sources, and the remainder arose from more distant sources. The outcome of this study is proving the atmospheric transport of microplastic far beyond its sources and a potential pathway for microplastics to the oceans and land through dust storm events.

In this study, levels and sources of aliphatic hydrocarbons and hopanes in surface sediments collected from rivers and estuaries of Peninsular Malaysia were assessed. The concentrations of total n-...

An efficient, reliable, and sensitive multiclass analytical method has been expanded to simultaneously determine 15 human pharmaceutical residues in fish and shrimp tissue samples by ultra-high-performance liquid chromatography-tandem mass spectrometry. The investigated compounds comprise ten classes, namely, analgesic, antibacterial, anticonvulsant, cardiovascular, fluoroquinolones, macrolides, nonsteroidal anti-inflammatory, penicillins, stimulant, and sulfonamide. A simple liquid extraction procedure based on 0.1% formic acid in methanol was developed. Chromatographic conditions were optimized, and mobile phase A was 0.1% ammonium acetate, and mobile phase B was acetonitrile. The mobile phase's gradient program was as follows: 0-2 min, 15% B; 2-5 min, linear to 95% B; 5-10 min, 95% B; and 10-12 min. The limits of detection were from 0.017 to 1.371 μg/kg, while a quantification range was measured from 0.051 to 4.113 μg/kg. Finally, amoxicillin, azithromycin, caffeine, carbamazepine, ciprofloxacin, clarithromycin, diclofenac, erythromycin, furosemide, ibuprofen, ketoprofen, naproxen, sulfamethoxazole, tetracycline, and triclosan were quantifiable in fish and shrimp samples.

Samples of fresh snow (n = 34) have been collected from 29 locations in various urban and remote regions of northern Iran following a period of sustained snowfall and the thawed contents examined for microplastics (MPs) according to established techniques. MP concentrations ranged from undetected to 86 MP L−1 (mean and median concentrations ~20 MP and 12 MP L−1, respectively) and there was no significant difference in MP concentration between sample location type or between different depths of snow (or time of deposition) sampled at selected sites. Fibres were the dominant shape of MP and μ-Raman spectroscopy of selected samples revealed a variety of polymer types, with nylon most abundant. Scanning electron microscopy coupled with energy-dispersive X-ray analysis showed that some MPs were smooth and unweathered while others were more irregular and exhibited significant photo-oxidative and mechanical weathering as well as contamination by extraneous geogenic particles. These characteristics reflect the importance of both local and distal sources to the heterogeneous pool of MPs in precipitated snow. The mean and median concentrations of MPs in the snow samples were not dissimilar to the published mean and median concentrations for MPs in rainfall collected from an elevated location in southwest Iran. However, compared with rainfall, MPs in snow appear to be larger and more diverse in their shape and composition (and include rubber particulates), possibly because of the greater size but lower terminal velocities of snowflakes relative to raindrops. Snowfall represents a significant means by which MPs are scavenged from the atmosphere and transferred to soil and surface waters that warrants further attention.

Magnetic properties of root, bark, and leaf of mangrove (Avicenna marina) and sediment were determined for pollution assessment at three locations in the northern coast of the Persian Gulf. The study revealed that the sources of the particles deposited on leaf surfaces can be discriminated via saturation isothermal remanent magnetization (SIRM) values and heavy metal. However, different factors including wind direction, size of the magnetic particles and crown density, play a role using SIRM for biomonitoring of atmospheric particulate matter. For leaves, the significant correlations between SIRM and leaf elemental contents indicated that the deposited particles on their surface mainly have geogenic sources. The magnetic analyses revealed that leaves are more suitable than bark for monitoring atmospheric pollution using mangrove trees due to the effect of different factors including dense crown of trees, washing of tree trunk by sea waves, and elements translocation from roots and sediments. Instead, the positive and significant correlation between the SIRM values for sediments and mangrove roots, and no or negative correlation between sediments and roots with barks and leaves indicates that the magnetic properties of the sediments and mangrove roots are suitable indicators of pollution in aquatic environment.

Although the distribution of microplastic (MPs) has been studied in different environmental compartments during the last decade, there is still a knowledge gap in their distribution and abundances in soil. This study aimed to investigate the abundance, distribution, and type of MPs in the soil of Aghili plain as a hot and dry area in southwest of Iran. In this study, composite soil samples (n=102) were collected from the residential and agricultural areas in Aghili plain, Iran. A combination of visual observations, Scanning Electron Microscopy (SEM) – Energy-dispersive X-ray spectroscopy (EDS), and Raman micro -spectroscopy was conducted to quantify and characterize MPs in soil samples. The intakes of MPs in adults and children were estimated through two exposure EPA scenarios. The total MPs loading in the studies soil was 11.93 ± 0.9 items in Kg-1 of surface soil in Aghili plain. The MPs had various morphology (fiber, pellet, fragment, and spherule shapes), colors (white-transparent, yellow-orange, red-pink, blue-green and black-grey colors), and sizes (

Dust storms are common events in arid and semi-arid regions that have a wide range of impacts on the environment and human health. This study addresses the presence, characteristics and potential sources of microplastics (MPs) in such events by analysing MPs deposited with dust particles in the metropolis of Shiraz, southwest Iran, following an intense storm in May 2018. At 22 locations throughout the city, MP concentrations on a number basis ranged from 0.04 to 1.06 per g of dust (median = 0.31 MP g−1). Particles were mainly fibrous, with a mean diameter of about 20 μm and >60% under 100 μm in length, and polymer makeup was dominated by nylon, polypropylene and polyethylene terephthalate. Examination of selected MPs by scanning electron microscopy revealed varying degrees of weathering and contamination by extraneous geogenic particles amongst the samples. Using published MP concentrations in urban dusts and remote, arid soils, we estimate that between about 0.1 and 5% of MPs deposited by the dust storm are derived from local sources within the metropolis, with the remainder arising from more distant sources. HYSPLIT modelling, satellite imagery and published geochemical signatures of regional dust particles suggest that the deserts of Saudi Arabia constitute the principal distal and transboundary source. Dust storms may represent a significant means by which MPs are transported and redistributed in arid and semi-arid environments and an important source of MPs to the oceans.

Microplastics (MPs) are contaminants of emerging concern that attracted the attention of researchers over the last decade. They can occur in saliva and stool, and on scalp hair together with skin. Further, MPs can end up in the human diet through seafood, honey, salt, and mineral water. They can be taken up into the plants' roots and lead to the occurrence of MPs in fruits and vegetables. Concentration of the airborne MPs was also reported in the environment. These pieces of evidence clarify that introduction of MPs to the human body through ingestion and inhalation routes should not be overlooked. Following oral exposure to MPs, hazardous chemicals can be released in the gastrointestinal tract leading to toxicity. Inhalation route deserves more attention due to the oxidative potential of the inhaled plastic particles. Although the major characteristics of MPs are being investigated, there are currently few regulations to control concentration of MPs in the environment and their human health impacts remained unclear indicating the need for further investigation. For instance, it is not clear if the present air quality limits for PM

Pharmaceutical residues and nanoplastic and microplastic particles as emerging pollutants in the aquatic environment are a subject of increasing concern in terms of the effect on water sources and marine organisms. There is lack of information about pharmaceutical-nanoplastic and pharmaceutical-microplastic mixtures. The present study aimed to investigate the fate and effect of pharmaceutical residues and nanoplastic and microplastic particles, the results of combinations of pharmaceutical residues with nanoplastic and microplastic particles, and toxic effects of pharmaceutical residues and nanoplastic and microplastic particles. Moreover, the objective was also to introduce analytical methods for pharmaceuticals, along with instrumental techniques for nanoplastic and microplastic particles in aquatic environments and organisms. PhAC alone can affect marine environments and aquatic organisms. When pharmaceutical residues combine with nanoplastic and microplastic particles, the rate of toxicity increases, and the result of this phenomenon constitutes this kind of pollutant in wastewater. Hence, the rate of mortality in organisms enhances. This study aimed to investigate the effect of pharmaceuticals residues and nanoplastic and microplastic particles, and a mixture of pharmaceutical residues and nanoplastic and microplastic particles in aquatic biota. Another object was survey methods for recognizing pharmaceutical residues and nanoplastic and microplastic particles. The findings show that pharmaceutical residues in organisms caused cell structure damage, inflammatory response, and nerve cell apoptosis. This study aimed to investigate the effect of microplastic particles in the human food chain and their impact on human health. Moreover, this review aims to present an innovative methodology based on comprehensive analytical techniques used to determine and identify pharmaceuticals adsorbed on nano- and microplastics in aquatic ecosystems. Finally, this review addresses the knowledge gaps and provides insights into future research strategies to better understand their interactions.

Microplastics and nanoplastics have a range of impacts on the aquatic environment and present major challenges to their mitigation and management. Their transport and fate depend on their composition, form, and the characteristics of the receiving environment. We explore the spatial and temporal dynamics of plastic particles in the world's second-largest hypersaline lake, combining information from microscopic, thermal gravimetric, and fractional methods. Studies on microplastic and nanoplastic pollution in these important environments are scarce, and there is limited understanding of their dynamics and fate. Our results for Urmia Lake (Iran) in 2016 and 2019 show a discrepancy in the composition and quantity of microplastics measured in river tributaries to the lake and the lake itself, suggesting an active microplastic sink. Potential sink mechanisms in hypersaline lakes are explored. The present study indicates that microplastics have different transport mechanisms and fate in these extreme environments, compared to lake and ocean environments.

Pharmaceuticals, microplastics, and oil spills are the most hazardous contaminants in aquatic environments. The COVID-19 pandemic enhanced pharmaceutical and microplastic contamination in aquatic environments. The present study aimed to investigate the prevalence of pharmaceutical and microplastic pollution on a global scale. This study assessed the results of pharmaceutical contamination in 25 countries and microplastic pollution in 13 countries. The findings show that pharmaceutical residues were detected in surface water, groundwater, and wastewater influents and effluents. In total, 43 types of pharmaceutical products were detected in 25 countries. Caffeine, acetaminophen, ibuprofen, sulfamethoxazole, and carbamazepine were the most abundant. In total, 32 types of polymers were detected in 13 countries. In the case of microplastics, polypropylene, polyethylene, polystyrene, and polyethylene terephthalate were the more abundant polymers. Particles with a size of 1–2.5 mm and 2.5–5 mm accounted for half of the microplastics present in 13 countries. This study provides new evidence of the importance of emerging pollutants in aquatic environments before and during the COVID-19 pandemic.

Dual high energy X-rays have been used for scanning large and dense cargo containers because of their high penetration depth of several meters. Low dependence of attenuation coefficient to the atomic number of materials at high energy X-rays makes the material discrimination so sophisticated in large containers. In this study, a linear function versus the material atomic number is introduced to identify the materials of large container, by involving the response of material attenuation at two energy spectra. Results verify the possibility of separating atomic numbers of materials with a unit resolution using the proposed method.

Pollution characteristics and associated ecological risks of PAHs in sediments from Brunei Bay, Brunei were investigated. The concentrations of ∑16 PAHs ranged from 826.7 to 2955.3 μg kg

Despite the significance of groundwater to the hydrological cycle and as a source of potable water, very little information exists on microplastics (MPs) in this environment. In the present study, MPs have been determined in ten well samples obtained from an alluvial aquifer in a semi-arid region (Shiraz, Iran) following filtration, digestion and inspection under a binocular microscope. A total of 96 MPs were identified, and concentrations ranged from 0.1 to 1.3 MP L

Microplastics and nanoplastics have a range of impacts on the aquatic environment and present major challenges to their mitigation and management. Their transport and fate depend on their composition, form, and the characteristics of the receiving environment. We explore the spatial and temporal dynamics of plastic particles in the world's second-largest hypersaline lake, combining information from microscopic, thermal gravimetric, and fractional methods. Studies on microplastic and nanoplastic pollution in these important environments are scarce, and there is limited understanding of their dynamics and fate. Our results for Urmia Lake (Iran) in 2016 and 2019 show a discrepancy in the composition and quantity of microplastics measured in river tributaries to the lake and the lake itself, suggesting an active microplastic sink. Potential sink mechanisms in hypersaline lakes are explored. The present study indicates that microplastics have different transport mechanisms and fate in these extreme environments, compared to lake and ocean environments.

In the middle of May 2018, an unprecedented dust storm occurred in the Shiraz metropolis. After the storm, several samples were collected from dust that settled around the city. These dust samples were analysed for potentially toxic elements (PTEs), rare earth elements (REEs), and radionuclides. This work is the first study that considered rare earth elements (REEs) for source identification and radionuclide contamination of Shiraz dust event. Hysplit model analysis and NASA and NOAA satellite maps illustrated that the air mass affecting Shiraz was moving mainly through the Saudi Arabian deserts. In addition, REE results of the dust that settled in Shiraz showed a trend similar to shale, sandstone, and especially Saudi Arabian soils. Ti/Al (0.01), Fe/Al (0.92), and Mg/Al (0.55) ratios and the values of LaN/SmN (0.91–0.98), GdN/YbN (1.8–2), LaN/YbN (1.7–1.9), HREE/LREE (0.52–0.6), Ce/Ce∗ (1.09–1.13), Eu/Eu∗ (1.03–1.18), Pr/Pr∗ (0.85–0.87), Gd/Gd∗ (1.1–1.15), and MREEs/MREE∗ (4.3–4.5) ratios provided insights into dust sources. These values indicated that Shiraz dust was affected by Asaluyeh and Iraq soils during transport and the main source of the dust that settled in Shiraz on the May 13, 2018 was Saudi Arabian soil. The concentrations of Mo, Cu, Pb, Zn, Ni, Co, Mn, As, Cd, Ti, Al, Sc, and Fe in the settled dust were 0.24, 47.67, 67.33, 244, 70.27, 19.33, 664, 8.39, 0.65, 537.33, 40933.33, 11.54, and 37800 mg/kg, respectively. According to the enrichment factor (EF), coefficient variation, and Positive Matrix Factorization (PMF) model the Mo, Cu, Pb, Zn, and Cd mainly originated from exhaust emissions and industrial activities. The activity concentrations of the radionuclides 7Be, 4 K, 137Cs, and 235U in the Shiraz-settled dust were 814, 421, 14, and 5.4 Bq kg−1, respectively and the activity concentration of 4 K was higher than the crustal average. Health risk assessment indices for the elements considering all three pathways revealed the following trend: dermal contact (HQderm)< inhalation (HQinh)< ingestion (HQing). The values of HQinh and HQing for children were higher than adults, while the values for the skin adsorption pathway for adults were higher than for children.

Microplastics (MPs) are ubiquitous and pervasive contaminants whose impacts on human health are unclear but are gaining interest in the scientific literature. Human exposure to MPs may arise through inhalation and ingestion, with research into the latter route focusing on foodstuffs and beverages contaminated from the environment or during processing and preparation. What has not been considered thus far, however, is MP exposure through geophagy, or the cultural, culinary or compulsive ingestion of contaminated soil and dirt. In this study, soils from the island of Hormoz, Iran, and spices prepared from these soils were analysed for MP contamination. Fibres of polyethylene terephthalate, Nylon, polystyrene or polypropylene were detected in the soils and a composite spice derived from packaged products, with the MP concentration greatest in the latter sample (0.1 M P g-1). Although typical consumption of this material results in MP exposure that is lower than that arising from the dietary consumption of fish and bottled water, for example, geophagy more generally may represent a more significant means of exposure for humans and animals that deliberately ingest geosolids.

The objectives of the current study are to investigate the concentration, biological risks, chemical speciation, and mobility of of heavy metals and also the determination of their distribution, physicochemical characteristics, and abundance of microplastics in coastal sediments and edible bivalves in the Persian Gulf, the coastal area of Hormozgan Province. Sampling points were selected considering the location of industrial, urban and Hara forest protected areas. In November 2017, a total of 18 sediment samples from coastal sediments (top 0-10 cm) and the most consumed bivalve species in the region were collected from two stations, Lengeh and Bandar Abbas Ports. The average concentration of heavy metals (except for Ni and Cd) in the sediments were lower than their average shale and the upper continental crust. Enrichment factors revealed significant enrichment of Ni, Mn, Cr, Cd and As. The fractionation of heavy metals using the Community Bureau of Reference (BCR) sequential extraction scheme indicated the high bioavailability of Zn, As, Mn, and Co. In general, the highest concentration of Mo, Cd, Pb, Zn, Cr, Cu, Mn, Hg, and Sb was detected in areas with frequent human activities including Shahid Rajaee Port, Shahid Bahonar Port, and Tavanir station. Shahid Rajaee and Shahid Bahonar Ports are the most important ports on the coast of Hormozgan province. The Risk Assessment Code calculated for the study elements indicates that As, Co, Zn, and Cu pose a moderate environmental risk a threat to the aquatic biota. Health risks of most heavy metals arising from bivalves consumption were safe, except for As which is associated with the high target cancer risk values. With reference to the type of microplastics found, they were mainly fibeours with lengths ranging between 100 and 250 μm in sediments and bivalves. Most of the microfibers found in the sediments were made of polyethylene terephthalate (PET) and polypropylene (PP), and the fibers found in the bivalves were made of PP. [Abstract copyright: Crown Copyright © 2021. Published by Elsevier Inc. All rights reserved.]

Although microplastics (MPs) are ubiquitous contaminants in different ecosystems, their interactions with other pollutants including heavy metals remain relatively unknown. Wheat is an important grain that makes the basis of human food in many parts of the world. Thus, pollutants that affect its production are important subjects of study. This research focuses on the possible effects of the transport of the adsorbed heavy metals onto MPs to the roots of growing wheat. The adsorption of three heavy metals (Pb, Cd, and Zn) onto PET particles was examined. Pb and Cd were selected because they are known to be toxic, while Zn is an essential nutrient for plants. Adsorption experiments were performed using 1 g of PET-MP particles in 20 ml of five different concentrations of each individual element (Pb, Cd, and Zn) (denoted as S-elements). To investigate the antagonistic and synergistic effects of these elements on each other, they were studied collectively with all 3 elements present (denoted as C-elements). Desorption experiments were then performed for three scenarios in which the wheat rhizosphere zone was simulated. Generally, the concentration of the investigated heavy metals adsorption on polyethylene terephthalate (PET) decreased in the order: S-Cd > S-Zn > S-Pb and C-Zn > T-Cd > C-Pb. PET particles exposed to Zn, Cd, and Pb solution adsorbed from 7.2 to 8.5%, 5.3 to 9.8%, and 29.8 to 68.5% of the initial heavy metals concentration, respectively. 11.3 to 15.2%, 12.5 to 23.35%, and 5.5 to 33.6% of the initially adsorbed Zn, Cd, and Pb were desorbed in the wheat rhizosphere zone in the three defined scenarios, respectively. The results show that PET particles can act as a vector in transferring heavy metals to the rhizosphere zone.

The current study is the intented to investigate the intensity of pollution, source characterization, oxidative potential, and human health risks of fourteen potentially toxic elements in the street dust of the Middle East oldest oil refinery zone. Thirty five street dust samples were collected from various regions in Abadan and Khorramshahr cities. The mean concentration of As, Mo, Cu, Pb, Hg, Zn, Cd, and Sb in Abadan street dust were 5.55, 3.39, 83.68, 49.82, 4493.54, 281.24, 1.15,and 1.17, while in Khorramshahr As, Mo, Cu, Pb, Hg, Zn, Cd, and Sb were.14, 2.58, 74.35, 56.50, 0.74, 214.26, 0.62, and 1.18, respectively. The concentration of these elements in both cities is higher than the local background values. Potential ecological risk index and pollution load index at all stations of both cities are greater than 1, indicating a high pollution load in the study area. Calculated enrichment factor showed high enrichment of Hg, Sb, Cd, Mo, Cu, Pb, and Zn in both areas. Of particular concern is the enrichment factor for mercury which proved to be 3370.54 ppb in the vicinity of the petrochemical unit in Abadan city (EF > 40). The results of positive matrix factorization receptor model together with geochemical maps and multivariate statistics indicated that industrial activities (especially petrochemical industries) are responsible for Hg, Cu, and Zn pollution, while exhaust emissions are responsible for Mo, Pb, Cd, and Sb, and natural sources for Al, Cr, Mn, Fe, Co, and Ni. The percentage of OPAA in the region ranged from 15.1 to 26.4 and OPGSH ranged from 9.5 to 24.4. The percentage of OPTOTAL/μg (OPAA/μg + OPGSH/μg) values varied between 0.6 and 1. The health risk evaluation models indicated that specific attention should be paid to Hg, Cd, Pb, and Zn and that the higher oxidative potential of street dust recovered from polluted locations is also a matter of concern in Abadan and Khorramshahr Cities.

Knowledge distillation (KD) is a new method for transferring knowledge of a structure under training to another one. The typical application of KD is in the form of learning a small model (named as a student) by soft labels produced by a complex model (named as a teacher). Due to the novel idea introduced in KD, recently, its notion is used in different methods such as compression and processes that are going to enhance the model accuracy. Although different techniques are proposed in the area of KD, there is a lack of a model to generalize KD techniques. In this paper, various studies in the scope of KD are investigated and analyzed to build a general model for KD. All the methods and techniques in KD can be summarized through the proposed model. By utilizing the proposed model, different methods in KD are better investigated and explored. The advantages and disadvantages of different approaches in KD can be better understood and develop a new strategy for KD can be possible. Using the proposed model, different KD methods are represented in an abstract view., six pages, 6 figures

Microplastics (MPs) are a pervasive and ubiquitous environmental contaminant. However, very little information exists on the quantities or characteristics of MPs in the indoor setting. In the present study, MPs have been isolated from settled classroom dust samples collected from 50 schools in the city of Shiraz, Iran. Concentrations of MPs on a number basis ranged from about 80 to over 56,000 MP per g of dry dust and there was an increase in concentration towards the centre and southeast of the city. The geographical distribution is attributed to a larger population and student density, higher traffic loading and greater industrialization in the centre and southeast and a prevailing wind from the northwest. MPs were dominated by fibres of >250 μm in length, and Raman spectrometry and SEM-EDX analysis of selected samples revealed that MPs were mainly constructed of polyethylene terephthalate or polypropylene but were contaminated by various metals (e.g. lead, titanium, antimony) used as additives or acquired from the environment. Calculations using data for elementary schools indicate that children in the age range 6–14 years may be exposed to between about 5 and 440 MP day−1 through inadvertent ingestion. The health impacts of MPs on children are unknown but the results of the present study indicate a requirement for research in this area.

Commercially-important species of fish and a crustacean from four sites in the Musa estuary and a site in the Persian Gulf have been analysed for the presence and location of microplastics (MPs). A total of 828 MPs were detected in the guts (gastrointestinal tracts), skin, muscle, gills and liver of demersal and pelagic fish (Platycephalus indicus, Saurida tumbil, Sillago sihama, Cynoglossus abbreviatus) from all five sites and in the exoskeleton and muscle of the tiger prawn, Penaeus semisulcatus, from three sites. On an individual basis, MPs were most abundant in P. indicus (mean = 21.8) and least frequently encountered in P. semisulcatus (mean = 7.8), but when normalized on a mass basis, MPs ranged from 0.16 g-1 for C. abbreviatus to 1.5 g-1 for P. semisulcatus. Microscopic analyses (polarized light, fluorescence, SEM/EDS) revealed that MPs were mainly fibrous fragments (with a few angular fragments) of various colour and size ( 1000 μm) and with strong C and O signatures. Additional particles detected that were distinctly different in colour, morphology, brittleness and elemental composition (part-metallic, and containing Cu) were suspected of being fragments of antifouling paint. The means of entry of MPs into tissues not involved in digestion are unclear but could be related to translocation or adherence. Regardless of the mode of accumulation, the presence of MPs in heavily fished species of fish and crustacean raises concerns about the potential transfer of synthetic materials into humans.

Superparamagnetic iron oxide nanoparticles (SPIONs) are widely applied as magnetic resonance imaging (MRI) contrast agents and drug carriers in drug delivery systems (DDSs) for diagnostics and treatment of diseases. Observation of drug delivery, drug release, and monitoring of the treatment can be performed by MRI. Magnetic nanoparticles (MNPs) can be used as dual-mode agents for simultaneous MRI contrast and drug delivery. Application of dual-mode MRI-contrast and drug-carrier agent is especially useful in targeted DDS. In this study, we report on the preparation of captopril-coated MNPs as a new dual-mode agent for simultaneous MRI contrast and DDS. The influence of contrast agent on the longitudinal (T1) and transverse (T2, T2*) relaxation times was studied and it was found that the effect on T2 and T2* exceeds the effect on T1, which leads to darkening of the MR image. Release of captopril from γ-Fe2O3@SiO2@captopril system was studied at three pH values and it was established that the drug release at pH 1.2 was greater than that at pH 4.8 and 7.4. The obtained results show that MNPs loaded with captopril can be used as dual-mode MRI contrast agent and DDS system.

Knowledge distillation allows transferring knowledge from a pre-trained model to another. However, it suffers from limitations, and constraints related to the two models need to be architecturally similar. Knowledge distillation addresses some of the shortcomings associated with transfer learning by generalizing a complex model to a lighter model. However, some parts of the knowledge may not be distilled by knowledge distillation sufficiently. In this paper, a novel knowledge distillation approach using transfer learning is proposed. The proposed method transfers the entire knowledge of a model to a new smaller one. To accomplish this, unlabeled data are used in an unsupervised manner to transfer the maximum amount of knowledge to the new slimmer model. The proposed method can be beneficial in medical image analysis, where labeled data are typically scarce. The proposed approach is evaluated in the context of classification of images for diagnosing Diabetic Retinopathy on two publicly available datasets, including Messidor and EyePACS. Simulation results demonstrate that the approach is effective in transferring knowledge from a complex model to a lighter one. Furthermore, experimental results illustrate that the performance of different small models is improved significantly using unlabeled data and knowledge distillation., Comment: 21 pages, 6 figures, 7 tables. arXiv admin note: substantial text overlap with arXiv:2002.03321