Microplastics removal efficiency and risk analysis of wastewater treatment plants in Oman

Microplastics (MPs) have recently been documented as an emerging pollutant that poses a critical threat to environment. Wastewater treatment plants (WWTPs) are commonly regarded as significant contributors to the presence of MPs. This study aimed to assess the MPs load of three wastewater treatment facilities in Oman using various treatments, including MBR, SBR, and CAS. Wastewater samples from influent, effluent, and sludge were collected and analyzed to determine the concentration, morphology, size, color, and polymer type of the MPs. A set of sieves with a mesh size range of 1 mm-45 μm was used to for filtration. Oxidation treatment was applied for all samples using Fenton's reagent, followed by density separation by sodium chloride solution. The Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR- FTIR) method was utilized to test 10% from each sampling point to confirm the polymer types of the MPs. The pollution load index (PLI) and hazard index (HI) have been employed to assess the risk associated with the chemical toxicity and concentration of detected particles. The PROMETHEE method was used to rank the risk of sampling sites based on different criteria that posed potential ecological and human health risks. The results indicate that the average concentrations of 0.99 MP/L, 1.38 MP/L, and 0.93 MP/L were detected in the final treated effluent of WWTP A, WWTP B, and WWTP C, respectively. These concentrations correspond to overall removal efficiencies of 82.5%, 77.4%, and 79.2% for WWTP A, WWTP B, and WWTP C, respectively Most MPs found in tertiary effluent were smaller particles (425 μm) and fiber-shaped. The major types of MPs were polypropylene (PP), low-density polyethylene (LDPE), polyurethane (PU), polyethylene terephthalate (PET), and Polyvinyl chloride (PVC). This study showed that treated effluent and sludge release significant MPs into the environment.

A meta-analysis of potential biomarkers associated with microplastic ingestion in marine fish

Over the past decade, global reports have shown a rise in the harmful effects of microplastics (MPs) on marine fish. This study analysed marine species' biochemical biomarker responses to microplastic exposure, finding that MPs can induce oxidative stress in marine fish through meta-regression results. Overall, exposure to MPs resulted in the activation of antioxidant defence mechanisms, such as superoxide dismutase, catalase and glutathione reductase, detoxification enzymes such as glutathione-S-transferase, the detection of malondialdehyde, and inhibition of acetylcholinesterase. Moreover, results highlight oxidative stress biomarkers were activated in wild species that had ingested MPs, indicating potential harm to marine fish, as confirmed in experimental studies. Furthermore, even though MPs' exposure is better regulated in an experimental setting, it is challenging to replicate actual exposure and environmental factors. The study's findings show the need for more investigation into the hazardous consequences of exposure to environmental MPs on species surveyed in the maritime environment.

Insight into pyrolysis mechanism of plastic waste with C-O/C-N bonds in the backbone

Pyrolysis is an important method for efficiently recovering plastic monomers, fuels and chemicals from plastic waste. The depolymerization of the backbone structure of plastic waste is a key step of the pyrolysis process. Currently, researches on the pyrolysis mechanism of plastics with C-O/C-N bonds in the backbone are still not sufficiently in-depth and also lack systematic and comprehensive investigation. Therefore, this study for the first time comprehensively investigated both macroscopic and microscopic pyrolysis processes of plastics with C-O/C-N bonds in the backbone, and evaluated the difficulty of breaking different backbone linkages via bond dissociation energy (BDE) obtained by density functional theory (DFT) calculations to deeply reveal the pyrolysis mechanism. The results indicated that polyethylene terephthalate (PET) had a higher initial pyrolysis temperature and its thermal stability was slightly stronger than nylon 6. The backbone of PET was mainly decomposed via the cleavage of Cα-O on the alkyl side, while the degradation of nylon 6 backbone began with NH2 groups at the end of the backbone. The pyrolysis products of PET were mainly derived from the small molecular fragments, which were generated by the degradation of the backbone through the cleavage of CO bonds or CC bonds, while the pyrolysis products of nylon 6 were always dominated by caprolactam. In addition, based on the results of DFT calculations, it could be inferred that the cleavage of CC bond in PET backbone and the cleavage of its adjacent Cα-O were most likely to occur, which followed a competitive reaction mechanism. However, in pyrolysis of nylon 6, the conversion to caprolactam was mainly via the concerted reaction of amide CN bonds. Compared with the concerted cleavage of amide CN bond, the cleavage of CC bond in the backbone of nylon 6 was not predominant.

A new hotspot of macro-litter in the Rutland Island, South Andaman, India: menace from IORC

Supralittoral zones of 13 sandy beaches of remote Rutland Island were divided into three zones to identify the litter contamination, its source, pathway of plastic transport to determine the level of macro-litter contamination, and its impact on coastal biota. Owing to the floral and faunal diversity, apart of the study area is protected under Mahatma Gandhi Marine National Park (MGMNP). The supralittoral zones of each sandy beach (between low-tide and high-tide line) were individually calculated from 2021 Landsat-8 satellite imagery before conducting the field survey. The total area of the surveyed beaches was 0.52 km² (5,20,020.79 m²), and 317,565 litters representing 27 distinct litter types were enumerated. Two beaches in Zone-II and six in Zone-III were clean; however, all five in Zone-I were very dirty. The highest litter density (1.03 items/m²) was observed in Photo Nallah 1 and Photo Nallah 2, whereas the lowest (0.09 items/m²) was observed in Jahaji Beach. According to the Clean Coast Index (CCI), Jahaji Beach (Zone-III) is the very cleanest beach (1.74) while other beaches of Zone-II and Zone-III are clean. The findings of the Plastic Abundance Index (PAI) indicate that Zone-II and Zone-III beaches have a low abundance of plastics (< 1), while two beaches of Zone-I, viz., Katla Dera and Dhani Nallah, exhibited a moderate abundance of plastics (< 4) while a high abundance of plastics (< 8) was observed in the rest of three beaches of the same zone. The primary contributor of litter on Rutland's beaches was plastic polymers (60-99%), which were presumed to originate from the Indian Ocean Rim Countries (IORC). A collective litter management initiative by the IORC is essential in preventing littering on remote islands.

Elucidating the consequences of the co-exposure of microplastics jointly to other pollutants in bivalves: A review

The marine environment has numerous impacts related to anthropogenic activities including pollution. Abundances of microplastics (MPs) and other pollutants are continuously increasing in the marine environment, resulting in a complex mixture of contaminants affecting biota. In order to understand the consequences, a review of studies analyzing combined effects of MPs and other types of pollutants in bivalves has been conducted as species in this group have been considered as sentinel and bioindicators. Regarding studies reviewed, histological analyses give evidence that MPs can be located in the haemolymph, gills and gonads, as well as in digestive glands in the intestinal lumen, epithelium and tubules, demonstrating that the entire body of bivalves is affected by MPs. Moreover, DNA strand breaks represent the most relevant form of damage caused by the enhanced production of reactive oxygen species in response to MPs exposure. The role of MPs as vectors of pollutants and the ability of polymers to adsorb different compounds have also been considered in this review highlighting a high variability of results. In this sense, toxic impacts associated to MPs exposure were found to significantly increase with the co-presence of antibiotics or petroleum hydrocarbons amongst other pollutants. In addition, bioaccumulation processes of pollutants (PAHs, metals and others) have been affected by the co-presence with MPs. Histological, genetic and physiological alterations are the most reported damages, and the degree of harm seems to be correlated with the concentration and size of MP and with the type of pollutant.

Chemical and toxicological assessment of leachates from UV-degraded plastic materials using in-vitro bioassays

The broad use of plastics and the persistence of the material results in plastic residues being found practically everywhere in the environment. If plastics remain in the (aquatic) environment, natural weathering leads to degradation processes and compounds may leach from plastic into the environment. To investigate the impact of degradation process on toxicity of leachates, different types of UV irradiation (UV-C, UV-A/B) were used to simulate weathering processes of different plastic material containing virgin as well as recyclate material and biodegradable polymers. The leached substances were investigated toxicologically using in-vitro bioassays. Cytotoxicity was determined by the MTT-assay, genotoxicity by using the p53-CALUX and Umu-assay, and estrogenic effects by the ERα-CALUX. Genotoxic as well as estrogenic effects were detected in different samples depending on the material and the irradiation type. In four leachates of 12 plastic species estrogenic effects were detected above the recommended safety level of 0.4 ng 17β-estradiol equivalents/L for surface water samples. In the p53-CALUX and in the Umu-assay leachates from three and two, respectively, of 12 plastic species were found to be genotoxic. The results of the chemical analysis show that plastic material releases a variety of known and unknown substances especially under UV radiation, leading to a complex mixture with potentially harmful effects. In order to investigate these aspects further and to be able to give recommendations for the use of additives in plastics, further effect-related investigations are advisable.

Anti-predator behavioral responses of Italian agile frog tadpoles (Rana latastei) exposed to microplastics

Microplastics (MPs) are nowadays abundant, persistent, and ubiquitous in the environment, representing a new threat for terrestrial, marine, and freshwater ecosystems. Although anuran populations and species are globally declining, the effect of MP exposure on this taxon has been poorly investigated. With the aim of assessing the effects of microplastic exposure on the defensive responses of Italian agile frog (Rana latastei) tadpoles, we exposed them to three different concentrations (1, 7, and 50 mg L^-1) of a mixture of plastic polymers (HPDE, PVC, PS, and PES) for 2 weeks. Then, we measured the total distance covered by individual tadpoles before and after exposure to tadpole-fed dragonfly larvae (Aeshna cyanea) cues. As expected, predation risk sharply lowered the total distance travelled by tadpoles; however, MP concentration did not affect their defensive performances. We also collected data on tadpole development, activity, and mortality. In contrast with previous experiments, neither tadpole growth nor mortality varied with MP concentration. Our results indicate that the intensity of MP effects on growth and development may depend on tadpole size, with large tadpoles being less susceptible to the negative effects of MP exposure.

Microplastics in sewage sludge destined to anaerobic digestion: The potential role of thermal pretreatment

Microplastics (MPs) are plastic particles with size smaller than 5 mm: their removal in municipal wastewater treatment plants mostly results in the accumulation of the coarser fraction into the sludge. The common application of the treated sludge as soil amendment raises the issue of the uncontrolled release of MPs into the environment, which depicts the need to identify suitable counteraction strategies. This work briefly reviews the most recent studies that focus on the fate of MPs during conventional sludge treatments, and, based on the results of this analysis, proposes the thermal pretreatment (120 °C, 30 min) of waste activated sludge (WAS) containing different kinds of MPs, in order to investigate its effect on the anaerobic biodegradability as well as on the abundance and physical features of MPs. Experimental results show that high temperatures did not alter polyethylene terephthalate (PET) MPs but the biodegradable-compostable ones (BIO-MPs), complying with the UNI EN 13432 standards. The profile of methane generation from thermally pretreated samples containing PET-MPs do not indicate any inhibition of the anaerobic process, which was positively influenced by the BIO-MPs in WAS: a 100% and 25% methane increase was observed over the control samples with and without the thermal pretreatment, respectively. Further studies are needed to better understand the mechanisms underlying biodegradable MPs behavior as well as to investigate the influence of high temperature treatments on smaller size MPs during anaerobic processes.

A temporal assessment of microplastics distribution on the beaches of three remote islands of the Yasawa archipelago, Fiji

This is the first study that investigated the presence, distribution, and composition of microplastics, MPs (1-5 mm) on beaches in the Yasawa Islands, Fiji. A temporal assessment over three years on six beaches was undertaken to investigate different beach traits on MP abundance. Average MP concentration was 4.5 ± 11.1 MPs·m^-2 with significantly higher concentrations were found on east-facing beaches than west (p < 0.001), and higher on the storm line compared to the high tide line (p < 0.001). No difference was found between tourist and local beaches (p = 0.21). These results demonstrate the role of current-driven ocean transport of plastic pollution in this part of The South Pacific. ATR FT-IR analysis showed that across all sites 34 % of MPs were polypropylene (PP), 33 % polystyrene (PS), 25 % polyethylene (PE), and 8 % other polymer types. Further studies are needed to assess the potential impacts of MPs on Fiji's coral reefs and marine life.

Assessment, characterization, and quantification of microplastics from river sediments

Microplastic (MP), as a pollutant, is currently posing a biological hazard to the aquatic environment. The study aims to isolate, quantify, and characterize the MP pollutants in sediment samples from 14 study sites at Kaveri River, Killa Chinthamani, Tiruchirappalli, South India. With Sediment-MP Isolation (SMI) unit, density separation was done with a hydrogen peroxide solution. Four forms of MPs namely, fragments, films, foams, and fibers with orange, white, green, and saffron red were observed. The plenitude and distribution of four forms of MPs and natural substrates were geometrically independent, with large amounts of microfragments within the research region accounting for 79.72% variation by Principal Component Analysis. FT-IR analyses of MPs showed the presence of polyamide, polyethylene, polyethylene glycol, polyethylene terephthalate, polypropylene, and polystyrene. Additionally, the scanning electron microscopic analysis revealed that the MPs have differential surface morphology with rough surfaces, porous structures, fissures, and severe damage. Most MPs comprised Si, Mg, Cu, and Al, according to energy dispersive X-ray analyses. The combined SMI, instrumental analyses and evaluation (heat map) of MPs in river sediments help assess contamination levels and types of MPs. The findings might provide an insight into the status of MPs in Kavery River sediments that could help in formulating regulations for MPs reduction and contamination in rivers eventually to protect the environment.

Differential effects of microplastic exposure on anuran tadpoles: A still underrated threat to amphibian conservation?

Microplastics (MPs) have been reported to threaten a wide variety of terrestrial, marine, and freshwater organisms. However, knowledge about the effects of MPs on anuran amphibians, one of the most threatened taxa worldwide, is still limited. To assess the effects of MPs on the growth and survival of the Italian agile frog (Rana latastei) and green toad (Bufotes balearicus), we exposed tadpoles to three different concentrations (1, 7, and 50 mg L^-1) of an environmental relevant mixture of microplastics (HPDE, PVC, PS and PES), recording data on their activity level, weight and mortality rates. While the effects of MPs on green toad tadpoles were negligible, Italian agile frog tadpoles were severely affected both in terms of growth and activity level, with high mortality rates even at the lowest MP density (1 mg L^-1). Our results suggest that MP contamination of freshwater habitats may contribute to the ongoing decline of anuran amphibians.

Floating microplastic debris in a rural river in Germany: Distribution, types and potential sources and sinks

Microplastic debris affects marine as well as freshwater ecosystems and an increasing number of studies have documented the contamination in aquatic environments worldwide. However, while the research focuses on oceans and larger rivers, little is known about the situation in smaller rivers within rural catchments. Since microplastics pose various risks to ecosystems, wildlife and human health, it is important to identify potential sources, sinks and transport patterns, which are probably different for small rivers. In this study, we investigate the contamination with microplastic debris of the river Ems, representing a smaller river in Northwest Germany with an agricultural catchment. We hypothesised that with increasing river length the plastic concentration increases, especially downstream of towns, waste water treatment plant (WWTP) effluents and major tributaries as they may be important point sources of microplastics. We collected 36 surface water samples at 18 sampling sites within the first 70 km using manual driftnets. We sampled every 7 km and upstream and downstream of three larger towns, four major tributaries and four WWTP effluents. Overall, we found 1.54 ± 1.54 items m^-3, which corresponds to the plastic concentrations in larger streams. However, the shape of the detected items differed as we did not find potential primary microplastic. Furthermore, the pattern contradicts our assumption, that the contamination increased with distance to the river's source. Downstream of towns, we found significantly less floating microplastic indicating possible sinks due to sedimentation at sites with slowing flow velocity caused by weirs in towns. Hence, the non-linear distribution pattern of microplastics indicates potential sinks of microplastics due to flow alterations on the river course. This should be considered in future studies modelling microplastic distribution and transport. Furthermore, studies especially in smaller rivers are urgently needed to identify and quantify sources and sinks and to find applicable solutions to reduce microplastic loads.

Biodegradation of plastic polymers by fungi: a brief review

Plastic polymers are non-degradable solid wastes that have become a great threat to the whole world and degradation of these plastics would take a few decades. Compared with other degradation processes, the biodegradation process is the most effective and best way for plastic degradation due to its non-polluting mechanism, eco-friendly nature, and cost-effectiveness. Biodegradation of synthetic plastics is a very slow process that also involves environmental factors and the action of wild microbial species. In this plastic biodegradation, fungi play a pivotal role, it acts on plastics by secreting some degrading enzymes, i.e., cutinase`, lipase, and proteases, lignocellulolytic enzymes, and also the presence of some pro-oxidant ions can cause effective degradation. The oxidation or hydrolysis by the enzyme creates functional groups that improve the hydrophilicity of polymers, and consequently degrade the high molecular weight polymer into low molecular weight. This leads to the degradation of plastics within a few days. Some well-known species which show effective degradation on plastics are Aspergillus nidulans, Aspergillus flavus, Aspergillus glaucus, Aspergillus oryzae, Aspergillus nomius, Penicillium griseofulvum, Bjerkandera adusta, Phanerochaete chrysosporium, Cladosporium cladosporioides, etc., and some other saprotrophic fungi, such as Pleurotus abalones, Pleurotus ostreatus, Agaricus bisporus and Pleurotus eryngii which also helps in degradation of plastics by growing on them. Some studies say that the degradation of plastics was more effective when photodegradation and thermo-oxidative mechanisms involved with the biodegradation simultaneously can make the degradation faster and easier. This present review gives current knowledge regarding different species of fungi that are involved in the degradation of plastics by their different enzymatic mechanisms to degrade different forms of plastic polymers.

Hallmarking microplastics of sediments and Chamelea gallina inhabiting Southwestern Black Sea: A hypothetical look at consumption risks

The consumer preference of bivalves originating from fishery or aquaculture has gained momentum in response to higher nutrition, quality, and market availability. However, potential toxicity caused by plastics, the pollution icons of the current era, could raise concerns for the sources of essential nutrients provided by bivalves. Thus, we investigated the abundance, spatial distribution, polymer composition, size, and the shapes of the microplastics (MPs) in the sediment and Chamelea gallina from 15 sites at gradual depths (10 and 30 m) along the Southwestern Black Sea coast. The abundance of the MPs ranged from 28 to 684 MP kg^-1 in the sediments and the amount of 0.22-2.17 MP individual^-1 (or 0.20-2.16 MP g^-1 fresh weight soft tissue) in C. gallina. Seven types of polymers were detected by FTIR, and the most abundant type was polyethylene terephthalate (34.2-35.1%), polyethylene (28-31.1%), and polypropylene (18.9-21%). MP sizes were ranged from 73 to 4987 μm. 47% and 65% of the MPs in the sediments and C. gallina, respectively, were <1000 μm in size. The most dominant shape of the MPs was found as fibers (56.5% for sediments and 68.9% for C. gallina). The risk data predicted that people are exposed to 304 MPs when consuming a single portion of C. gallina weekly. Hypothetical calculations performed with a chemical additive simulation (bisphenol A) showed that the risk associated with the MP-contaminated C. gallina model is negligible, and the consumption is rather beneficial due to already known positive aspects.

Microplastic pollution in perch (Perca fluviatilis, Linnaeus 1758) from Italian south-alpine lakes

Microplastic particles (MPs) contamination of aquatic environments has raised a growing concern in recent decades because of their numerous potential toxicological effects. Although fish are among the most studied aquatic organisms, reports on MPs ingestion in freshwater environments are still scarce. Thus, there is still much to study to understand the uptake mechanisms, their potential accumulation among the food webs and their ecotoxicological effects. Here, MPs presence in the digestive system of one of the most widespread and commercially exploited freshwater fish, the perch (Perca fluviatilis, Linnaeus 1758), was investigated in four different south-alpine lakes, to assess the extent of ingestion and evaluate its relation to the body health condition. A total of 80 perch specimen have been sampled from the Italian lakes Como, Garda, Maggiore and Orta. Microplastic particles occurred in 86% of the analysed specimens, with average values ranging from 1.24 ± 1.04 MPs fish^-1 in L. Como to 5.59 ± 2.61 MPs fish^-1 in L. Garda. The isolated particles were mainly fragments, except in L. Como where films were more abundant. The most common polymers were polyethylene, polyethylene terephthalate, polyamide, and polycarbonate, although a high degree of degradation was found in 43% of synthetic particles, not allowing their recognition up to a single polymer. Despite the high number of ingested MPs, fish health (evaluated by means of Fulton's body condition and hepatosomatic index) was not affected. Instead, fullness index showed an inverse linear relationship with the number of ingested particles, which suggests that also in perch MPs presence could interfere with feeding activity, as already described for other taxa.

Quantification of Microplastics in Soils Using Accelerated Solvent Extraction: Comparison with a Visual Sorting Method

Visual sorting is a method that is widely used in microplastic analysis, but it has limitation in the quantification of small-size microplastics. Accelerated solvent extraction (ASE) which frequently used in the analysis of organic contaminants in soils and sediments was used here for the microplastics quantification. A recovery experiment using different spiked polymeric microplastics separately indicates that ASE was useful in the extraction of low-density and low-melting point polymeric microplastics. High recoveries and low matrix effects were observed for the polyethylene, polypropylene and polystyrene microplastics. A further comparison between ASE and visual sorting was conducted for seven soils from agricultural land used for long-term mulching with plastic films. The results confirmed that ASE was capable of microplastics quantification for farmland soils and polyethylene film in the ASE extracts could be identified by Fourier transform infrared spectroscopy. Meanwhile, ASE conducted on small samples (3.0 g) gave results that showed close agreement with the visual sorting method.

What's in the soup? Visual characterization and polymer analysis of microplastics from an Indonesian manta ray feeding ground

Plastics in marine environments vary in their physical and chemical properties, influencing their risk to biota once ingested. Manta rays are large filter-feeders that ingest plastics. To assess this risk, we characterized the plastics in a critical feeding habitat off Nusa Penida, Indonesia. We examined the color and polymer composition of sampled small-sized plastics (<30 mm). Plastics were mostly secondary microplastics and transparent (46%), white/off-white (24%), and blue/green (22%). Fourier transform infrared spectroscopy of plastics grouped according to type (films, fragments, foam, or lines) and color indicated that most plastics were polyethylene (PE) or polypropylene (PP) (99%), with the remainder polystyrene and polyester. Visual characterization aligned with single polymer composition in seven out of ten groups. Although PE and PP have relatively low toxicity compared to other plastics, their composing monomers and associated pollutants and microbes are of concern to manta rays and other marine biota.

Identification and quantification of plastic additives using pyrolysis-GC/MS: A review

Analysis of organic plastic additives (OPAs) associated to plastic polymers is growing. The current review outlines the characteristics and the development of (multi-step) pyrolysis coupled with a gas chromatography mass spectrometer (Py-GC/MS) for the identification and semi-quantification of OPAs. Compared to traditional methods, Py-GC/MS offers advantages like suppressing extensive steps of preparation, limiting contamination due to solvents and the possibility to analyse minute particles. Its key advantage is the successive analysis of OPAs and the polymeric matrix of the same sample. Based on the studied articles, numerous methods have been described allowing identification and, in some case, semi-quantification of OPAs. There is nevertheless no gold standard method, especially given the huge diversity of OPAs and the risks of interferences with polymers or other additives, but, among other parameters, a consensus temperature seems to arise from studies. More broadly, this review also explores many aspects on the sample preparation like weight and size of particles and calibration strategies. After studying the various works, some development prospects emerge and it appears that methodological developments should focus on better characterizing the limits of the methods in order to consider which OPAs can be quantified and in which polymers this is feasible.

Plastic pollution threat in Africa: current status and implications for aquatic ecosystem health

Rapid population growth and poor waste management practice are among the main drivers of plastic pollution in modern times, thus making Africa a hotspot for plastic pollution both now and in the future. This study is a review of plastic pollution reports from the African aquatic environment with regard to causes, current status, toxicological implications and implications for ecosystem services. A total of 59 plastic pollution studies from 1987 to September 2020 were reviewed. They comprised 15 from North Africa (NA) (Algeria, Egypt, Morocco and Tunisia), six from East Africa (EA) (Ethiopia, Kenya, Tanzania and Uganda), 13 from West Africa (WA) (Ghana, Guinea-Bissau, Mauritania and Nigeria), and 25 studies from Southern Africa (SA) (South Africa). This shows that plastic pollution studies in Africa, according to the sub-regions, are in the order: SA > NA > WA > EA. High human population in the basins of African large aquatic systems is identified as the greatest driver enhancing plastic surge in the aquatic environment. The occurrence of plastics was mostly reported in the estuarine/marine environment (42 studies) compared to the freshwater environment (only 17 studies). Plastics have also been reported in the three compartments of the aquatic environment: water column, benthic sediment and animals. Zooplankton, annelids, molluscs, insects, fishes and birds were reported as bioindicators of plastic ingestion in the inland and coastal waters of Africa. Polyethylene, polyethylene terephthalate (polyester) and polypropylene were the common plastic polymers observed in the African aquatic environment. In situ toxicological implications of the ingested plastic polymers were not reported in any of the studies. However, reports from laboratory-controlled experiments showed that these polymers are deleterious to aquatic animal health. More research efforts need to delineate the plastic pollution status of the East, West and North of Africa. Furthermore, such studies are required to identify the plastic polymers and in situ ecotoxicological impacts of plastics on both animal and human health.

Comparative assessment of microplastics in water and sediment of a large European river

Aquatic ecosystems are globally contaminated with microplastics (MP). However, comparative data on MP levels in freshwater systems is still scarce. Therefore, the aim of this study is to quantify MP abundance in water and sediment of the German river Elbe using visual, spectroscopic (Fourier-transform infrared spectroscopy) and thermo analytical (pyrolysis gas chromatography mass spectrometry) methods. Samples from eleven German sites along the German part of the Elbe were collected, both in the water and sediment phase, in order to better understand MP sinks and transport mechanisms. MP concentrations differed between the water and sediment phase. Sediment concentrations (mean: 3,350,000 particles m^-3, 125-5000 μm MP) were in average 600,000-fold higher than water concentrations (mean: 5.57 particles m^-3, 150-5000 μm MP). The abundance varied between the sampling sites: In sediments, the abundance decreased in the course of the river while in water samples no such clear trend was observed. This may be explained by a barrage retaining sediments and limiting tidal influence in the upstream parts of the river. Particle shape differed site-specifically with one site having exceptionally high quantities of spheres, most probably due to industrial emissions of PS-DVB resin beads. Suspended MP consisted predominantly of polyethylene and polypropylene whereas sediments contained a higher diversity of polymer types. Determined MP concentrations correspond well to previous results from other European rivers. In a global context, MP levels in the Elbe relate to the lower (water) to middle section (sediment) of the global range of MP concentrations determined for rivers worldwide. This highlights that elevated MP levels are not only found in single countries or continents, but that MP pollution is an issue of global concern.

Presence of microplastics in water, sediments and fish species in an urban coastal environment of Fiji, a Pacific small island developing state

Microplastics (MP) in the marine environment are widely reported. However, MP occurrence in some geographical areas such as from Small Island Developing States (SIDS) is missing. The main aim of this study was to assess MP levels in the urban coastal environment of Suva, the capital of the Republic of Fiji. Microplastics were measured from surface water, sediments and fish gastrointestinal tracts (GI) from three sites adjacent to Suva. In addition, an evaluation on the contribution from the local sewage treatment plant to MP levels was undertaken. In general, low levels of MP in water and sediments were detected, but significant differences were observed among sites. The sewage treatment plant was shown to contribute to MP levels in sediment but not in water. Species ingestion of MP was high and associated with MP in sediments. Fibres and fragments were the predominant type of MP, and fifteen different polymers were detected, with higher percentages of polyethylene, latex and polypropylene. In conclusion, MP were found in Suva coastal environment and these MP were associated to land based human activities.

Converting polycarbonate and polystyrene plastic wastes intoaromatic hydrocarbons via catalytic fast co-pyrolysis

Thermochemical conversion of plastic wastes is a promising approach to produce alternative energy-based fuels. Herein, we conducted catalytic fast co-pyrolysis of polycarbonate (PC) and polystyrene (PS) to generate aromatic hydrocarbons using HZSM-5 (Zeolite Socony Mobil-5, hydrogen, Aluminosilicate) as a catalyst. The results indicated that employing HZSM-5 in the catalytic conversion of PC facilitated the synthesis of aromatic hydrocarbons in comparison to the non-catalytic run. A competitive reaction between aromatic hydrocarbons and aromatic oxygenates was observed within the studied temperature region, and catalytic degradation temperature of 700 °C maximized the competing reaction towards the formation of targeted aromatic hydrocarbons at the expense of phenolic products. Catalyst type also played a vital role in the catalytic decomposition of PC wastes, and HZSM-5 with different Si/Al molar ratios produced more aromatic hydrocarbons than HY (Zeolite Y, hydrogen, Faujasite). Regarding the effect of Si/Al molar ration in HZSM-5 on the distribution of monocyclic aromatic hydrocarbons (MAHs), a Si/Al molar ratio of 38 maximized benzene formation with an advanced factor of 5.1. Catalytic fast co-pyrolysis of PC with hydrogen-rich plastic wastes including polypropylene (PP), polyethylene (PE), and polystyrene (PS) favored the production of MAHs, and PS was the most effective hydrogen donor with a ∼2.5-fold increase. The additive effect of MAHs increased at first and then decreased when the PC percentage was elevated from 30 % to 90 %, achieving the maximum value of 32.4 % at 70 % PC.

Ingestion of plastic marine litter by sea turtles in southern Brazil: abundance, characteristics and potential selectivity

The ingestion of plastic marine litter (PML) by sea turtles is widespread and concerning, and the five species that occur in the southwestern Atlantic - green, loggerhead, olive ridley, leatherback and hawksbill - are vulnerable to this pollution. Here, we quantified and characterized PML ingested by these species in southern Brazil, and observed PML ingestion in 49 of 86 sampled individuals (~57.0%). Green turtles presented the highest rates and variety of ingested plastics, and such ingestion has been high at least since 1997. Omnivorous turtles presented higher PML ingestion than carnivorous ones. Loggerheads displayed a negative correlation between body size and number of ingested items. Green turtles ingested mostly flexible transparent and flexible/hard white plastics; loggerheads ate mainly flexible, hard and foam fragments, in white and black/brown colors. These results help us better understand PML ingestion by sea turtles, highlighting the seriousness of this threat and providing information for prevention and mitigation strategies.

Investigation on an innovative technology for wet separation of plastic wastes

This paper presents an original device for the separation of plastic polymers from mixtures. Due to the combination of a characteristic flow pattern developing within the apparatus and density, shape and size differences among two or more polymers, this device allows their separation into two products, one collected within the instrument and the other one expelled through its outlet ducts. Experimental tests have been conducted to investigate the effectiveness of the apparatus, using two geometric arrangements, nine hydraulic configurations and three selections of polymers at three stages of a material life cycle. Tests with samples composed of a single typology of polymer have been used to understand the interaction between the particles and the carrying fluid within the apparatus in different hydraulic configurations and geometric arrangements. Multi-material tests are essential to simulate the real conditions in an industrial recycling plant. The separation results have been evaluated in terms of grade and recovery of a useful material. Under the proper hydraulic configurations, the experimentation showed that it is possible to produce an almost pure concentrate of Polyethylene Terephthalate (PET) from a mixture of 85% PET and 15% Polycarbonate (PC) (concentrate grade and recovery equal to 99.5% and 95.1%) and a mixture of 85% PET and 15% Polyvinyl Chloride (PVC) (concentrate grade and recovery equal to 97.9% and 100.0%). It is further demonstrated that almost pure concentrates of PVC and PC can be produced from a mixture of 85% PVC and 15% PC (PVC grade and recovery equal to 99.9% and 99.7%) and a mixture of 85% PC and 15% PVC (PC grade and recovery equal to 99.0% and 99.5%).