First detection of microplastics in Xyrichtys novacula (Linnaeus 1758) digestive tract from Eivissa Island (Western Mediterranean)

Plastic waste and its ubiquity in the oceans represent a growing problem for marine life worldwide. Microplastics (MPs) are ubiquitous in the sea and easily enter food webs. Xyrichtys novacula L. is one of the main target species of recreational fishing in the Balearic Islands, Spain. In the present study, the quantity of MPs in gastrointestinal tracts of X. novacula from two different areas (a marine protected area (MPA) and a non-protected area) of Eivissa Island (in the Balearic archipelago) has been assessed, as well as MPs evaluation within the sediment of both areas. The results showed that over 80% of sampled individuals had MPs in their gut with an average of 3.9 ± 4.3 plastic items/individual. Eighty percent of these plastics were fibres, while the rest were fragments. Although the sediment of the non-protected area had a significant higher presence of MPs, no significant differences in the number of MPs were observed in X. novacula from both areas. The µ-FT-IR analysis showed that the main polymers in the sediments were polycarbonate (PC) and polypropylene (PP), whereas in the digestive tract of fish PC, PP, polyethylene, polystyrene and polyester. In conclusion, practically all X. novacula specimens presented MPs in their digestive tract regardless if the capture zone was in a MPAs or not. These results highlight the ubiquity of MPs in coastal marine areas, and further studies might be necessary to evaluate further implications of MP presence in this species.

Observational and model studies on transport and inventory of microplastics from a leak accident on the beaches of Yantai

We investigated an unexpected microplastic (MP) leakage event that occurred along the coastline of Yantai in January 2021. Sediment samples were collected from three zones on 9 beaches. MPs were identified with an average abundance of 247.6 ± 125.6 items/m² on 7 beaches. The total amount of MPs from the leak accident was estimated to be 1.50 × 10⁷ items (514.67 kg). The MPs were identified as polyethylene (PE), polypropylene (PP), and PP/PE blends using μ-FT-IR analysis. By utilizing a numerical model, the transmission process and potential source of MPs were demonstrated. The modeling results showed that the MPs might originate from the central and western part of the Bohai Sea and be driven to the beaches of Yantai by northwest wind and wind-induced surface current. However, due to the absence of direct evidence, the simulation results might only indicate the range of the leaking source, which was the movement trajectory of MPs.

A systematic study of microplastic occurrence in urban water networks of a metropolis

The release of microplastics from sewage treatment works (STWs) into the oceans around coastal cities is well documented. However, there are fewer studies on the microplastic abundance in stormwater drains and their emissions into the coastal marine environment via sewage and stormwater drainage networks. Here, we comprehensively investigated microplastic abundance in 66 sewage and 18 sludge samples collected from different process stages at three typical STWs and 36 water samples taken from six major stormwater drains during the dry and wet seasons in Hong Kong, which is a metropolitan city in south China. The results showed that microplastics were detected in all the sewage and stormwater samples, with the abundance ranging from 0.07 to 91.9 and from 0.4 to 36.48 particles/L, respectively, and in all the sludge samples with the abundance ranging from 167 to 936 particles/g (d. w.). There were no significant seasonal variations in the microplastic abundance across all samples of sewage, sludge, and stormwater. For both waterborne sample types, a smaller size (0.02-0.3 mm) and fiber shape were the dominant characteristics of the microplastics. Polyethylene terephthalate (PET) and polypropylene (PP) were the most abundant polymer types in the sewage samples, while polyethylene (PE), PET, PP, and PE-PP copolymer were the most abundant polymer types in the stormwater samples. The estimated range of total daily microplastic loads in the effluent from STWs in Hong Kong is estimated to be 4.48 × 10⁹ - 2.68 × 10¹⁰ particles/day, demonstrating that STWs are major pathways of microplastics in coastal environments despite the high removal percentage of microplastics in sewage treatment processes examined. This is the first comprehensive study on microplastics in the urban waters of a coastal metropolis. However, further studies on other coastal cities will enable an accurate estimation of the microplastic contribution of stormwater drains to the world's oceans.

First record of plastiglomerates, pyroplastics, and plasticrusts in South America

Beaches in the Anthropocene carry the heavy burden of human-derived pollution, like that induced by plastic litter. For decades, plastic debris has been classified based on its source or physical size. In recent years, studies described and documented new forms of plastic formations, including plastiglomerates, plasticrusts, and pyroplastics. However, reports of these newly described formations are substantially lacking. Therefore, in the present study, we reported the first evidence of plasticrusts (plastic encrusting rock surfaces), plastiglomerates (organic/inorganic composite materials in a plastic matrix), and pyroplastics (burned and weathered plastics) in Peru. The plastic pollutants were recovered from the field through marine litter surveys on four beaches where illegal litter burning and campfires take place. All the suspected plastic formations were analyzed and confirmed using Fourier transformed infrared (FTIR) spectroscopy, and one of each type was analyzed by X-Ray fluorescence (EDX) spectrometry. Plastiglomerates consisted of a high-density polyethylene (HDPE) or polypropylene (PP) matrix with rock and sand inclusions. Pyroplastics were found in various stages of weathering and consisted of various polymers, including HDPE, PP, polyethylene terephthalate (PET), and polyamide (PA). Interestingly, our field observations suggest a new plasticrust formation pathway based on plastic burning and filling of rock crevices with molten plastic. The latter was identified as either PP or HDPE. Elements typically found in the sand and seawater (e.g., Na, Cl, Ca, Si, Fe) were identified on the surface of the plastic formations, as well as others that could potentially be associated with the leaching of additives (e.g., Ti, Br). Although the present study contributed to the knowledge concerning the occurrence of the new types of plastic formations, as well as possible formation pathways, there are still many questions to answer. Hence, we encourage future studies to focus on the toxicity that new plastic formations may induce in contrast with conventional plastics, the release of secondary contaminants (e.g., microplastics, additives), and their degradation in the environment. Lastly, standardized sampling and data treatment protocols are required.

Identification and Quantification of Microplastics in the Marine Environment Using the Laser Direct Infrared (LDIR) Technique

Here, we evaluate for the first time the performances of the newly developed laser direct infrared (LDIR) technique and propose an optimization of the initial protocol for marine microplastics (MPs) analysis. Our results show that an 8 μm porosity polycarbonate filter placed on a Kevley slide enables preconcentration and efficient quantification of MPs, as well as polymer and size determination of reference plastic pellets of polypropylene (PP), polyethylene (PE), polystyrene (PS), polyvinyl chloride (PVC), and polyethylene terephthalate (PET), with recoveries ranging from 80-100% and negligible blank values for particle sizes ranging from 200 to 500 μm. A spiked experiment using seawater, sediment, mussels, and fish stomach samples showed that the method responded linearly with significant slopes (R² ranging from 0.93-1.0; p < 0.001, p < 0.01). Overall, 11 polymer types were identified with limited handling and an analysis time of ca. 3 h for most samples and 6 h for complex samples. Application of this technique to Mediterranean marine samples (seawater, sediment, fish stomachs and mussels) indicated MP concentrations and size distribution consistent with the literature. A high predominance of PVC (sediment, fish stomachs) and PE and PP (seawater, mussels) was observed in the analyzed samples.

Effect of land use on microplastic pollution in a major boundary waterway: The Arvand River

The occurrence of microplastics (MPs) was investigated in the Arvand River (Iran). The Arvand River (200 Km) is a major water body that flows through land with diverse use and it meets the Persian Gulf. This study constitutes the first assessment of MP pollution (prevalence and physico-chemical characteristics) in the Arvand river, both in the sediment and in the water. MP monitoring has been carried out in 24 stations located along the river. The MP pollution found ranged between 1 and 291 items·L^-1 and 70 to 15,620 items·kg^-1 (dw), in water and sediment, respectively. The majority of MPs were fibres, black/grey and yellow/orange in colour, and mainly 250-500 μm and >1000 μm in size. Polyethylene terephthalate (PET), polypropylene (PP), nylon (NYL), high-density polyethylene (HDPE), and polystyrene (PS) were found in sediment samples. All these polymers, except HDPE, were also identified in the water samples. PET and PP were dominant in the water samples; whereas PET and PS were the most abundant in the sediments. The vicinity of urban wastewater effluents could be behind MP pollution in both water and sediments. Significant differences (p < 0.05) of MP concentrations were affected by different land uses when comparing MP levels in undisturbed natural area with urban areas. A strong correlation between MP fibres and fragments found with PCA biplots revealed their similar distribution in water. In the sediment samples, fibre and fragment MP particles were significantly correlated with colloidal particles (e.g., clay and organic matter) suggesting a relevant role of colloidal particles in the aquatic ecosystem of the Arvand River in transporting MPs. This study contributes to the better understanding of the presence of MP in major rivers, which are systems that have been scarcely investigated for this type of pollution, and it can inform interventions to reduce MP inputs to the river and sea.

Polymer composition analysis of plastic debris ingested by loggerhead turtles (Caretta caretta) in Southern Tyrrhenian Sea through ATR-FTIR spectroscopy

The ingestion of anthropogenic plastic debris by marine wildlife is widespread in the Mediterranean Sea. The endangered status (in the IUCN Red List) of Loggerhead turtle (Caretta caretta, Linnaeus, 1758) is a consequence of its vulnerability. In this study, macro-/meso-plastics (5-170 mm) collected from faeces of twelve loggerhead turtles rescued (live) in the Aeolian Archipelago (Southern Tyrrhenian Sea, Italy) were analyzed by size, weight, shape, color and polymer type through Attenuated Total Reflectance Fourier-Transform Infrared Spectroscopy (ATR-FTIR). The defecation rate during hospitalization (7-14 days) varied among turtles (from 0.08 to 0.58). The mean number of plastic expulsions (2.7 ± 1.8 items for turtle) was higher during the 5th day of hospitalization (Kruskal-Wallis test, P = 0.01). However, the mean number of plastic-like items defecated during the common days of hospitalization did not vary among turtles (Kruskal-Wallis test, P > 0.05). All turtles were found to have ingested plastic. A total of 114 debris items were recovered from their faeces, 113 of which were identified as plastic. Their color was mostly white-transparent (64.9%) and light (19.3%). Shape was mainly fragments (52.6%), sheets (38.6%), followed by nylon, net-fragments, elastic plastic, foamed plastic and industrial granules (8.8%). Meso-plastics (5-25 mm) represented 72% of the total number of debris and were found more frequently in turtle with Curved Carapace Length (CCL) ≤ 60 cm (CCL = 30-60 cm, n = 5) than those with CCL >60 cm (CCL = 60-71 cm, n = 7). Plastic items were composed mainly of polyethylene (48.2%) and polypropylene (34.2%). Polypropylene (R² = 0.95, P < 0.001) and polyisoprene (R² = 0.45, P = 0.017) were more common in meso-plastics while polyethylene (R² = 0.44, P < 0.01) in macro-plastics. Finally, high-density polyethylene, polyvinyl chloride, polyamide and polyurethane were also found in some turtles. This study reveals high spreads of plastic contamination in faeces of both turtles with CCL ≤60 cm and CCL >60 cm, particularly vulnerable to the increasing quantity of floating plastic into their foraging sites highlighting the need of further research to associate debris ingestion with turtle diet and their size.

Small-sized microplastics (< 500 μm) in roadside soils of Beijing, China: Accumulation, stability, and human exposure risk

The potential threats of microplastics (MPs) to human health in urban environment have received increasing attention. Small MPs substantially threaten soil organisms and human beings because they are easily ingested and may adsorb other pollutants to form composite compounds. However, roadside soils as a source and a sink of small MPs in urban environments have not been reported. Here, we studied the small-sized MPs (SMPs, < 500 μm) pollution and human exposure analysis by investigating the MPs in roadside soils in Beijing. SMPs contributed to 88.06% of the high average MPs abundance (22001.67 ± 24482.34 items/kg), and were categorized as uncontaminated to moderately contaminated, assessed by the geo-accumulation index (I_geo). SMPs mainly consisted of polypropylene (PP) and polyethylene (PE) with morphotypes of fragment and granule. In particular, highly stable and fragmented MPs were discovered by the conditional fragmentation model. And normal-sized MPs (NMPs 500-5000 μm) NMPs could further fragment into SMPs, indicating that SMPs in roadside soil were further enriched. The estimated infant exposure to SMPs was greater than that in adults, and independent of the polymer types and morphotypes. PP is currently the main pollutant, contributing 65% to the estimated human exposure. Combining the conditional fragmentation model and main polymer types, SMPs likely derived from containers/packaging and fertilizers, and affected by atmospheric transport. This study demonstrated the dominance and potential risk of SMPs in roadside soil, suggesting that health risk assessment for SMPs in urban environment necessitates critical investigation.

Tracing microplastics from raw water to drinking water treatment plants in Busan, South Korea

The increasing amount of plastic waste has raised concerns about microplastics (MPs) in aquatic environments. MPs can be fragmented into nanoplastics that can pass through water treatment processes and into tap water; potentially threatening human health because of their high adsorption capacity for hazardous organic materials and their intrinsic toxicity. This case study investigates the identification, fate, and removal efficiency of MPs in Korean drinking water treatment plants. Two sites on the Nakdong River, two lake reservoirs (raw water sources), and four corresponding drinking water treatment plants were targeted to trace the amounts, types, and sizes of MPs throughout the treatment process. Monthly quantitative and qualitative analyses were conducted by chemical image mapping using micro-Fourier-transform infrared spectroscopy. MPs larger than 20 μm were detected, and their sizes and types were quantified using siMPle software. Overall, the number of MPs in the river sites (January to April and October to November) exceeded those in the reservoirs, but only slight differences in the number of MPs between rivers and lake reservoirs were detected from June to October. The annual average number of MPs in River A, B and Lack C and D was not distinctively different (2.65, 2.48, 2.46 and 1.87 particles/L, respectively). The majority of MPs found in raw waters were polyethylene (PE)/polypropylene (PP) (> 60%) and polyethylene terephthalate (PET)/poly(methyl methacrylate) (PMMA) (20%), in addition to polyamide (<10%) in the river and polystyrene (<10%) in the lake reservoirs. Approximately 70-80% of the MPs were removed by pre-ozonation/sedimentation; 81-88% of PE/PP was removed by this process. PET/PMMA was removed by filtration. Correlation of MPs with water quality parameters showed that the Mn concentration was moderately correlated with the MP abundance in rivers and lake reservoirs, excluding the lake with the lowest Mn concentration, while the total organic carbon was negatively correlated with the MP abundance in both rivers (A and B) and lake reservoir C.

Identification and Quantification of Nanoplastics in Surface Water and Groundwater by Pyrolysis Gas Chromatography-Mass Spectrometry

Nanoplastics (NPs) are currently considered an environmental pollutant of concern, but the actual extent of NP pollution in environmental water bodies remains unclear and there is not enough quantitative data to conduct proper risk assessments. In this study, a pretreatment method combining ultrafiltration (UF, 100 kDa) with hydrogen peroxide digestion and subsequent detection with pyrolysis gas chromatography-mass spectrometry (Py-GC/MS) was developed and used to identify and quantify six selected NPs in surface water (SW) and groundwater (GW), including poly(vinylchloride) (PVC), poly(methyl methacrylate) (PMMA), polypropylene (PP), polystyrene (PS), polyethylene (PE), and poly(ethylene terephthalate) (PET). The results show that the proposed method could detect NPs in environmental water samples. Nearly all selected NPs could be detected in the surface water at all locations, while PVC, PMMA, PS, and PET NPs were frequently below the detection limit in the groundwater. PP (32.9-69.9%) and PE (21.3-44.3%) NPs were the dominant components in both surface water and groundwater, although there were significant differences in the pollution levels attributed to the filtration efficiency of riverbank, with total mass concentrations of 0.283-0.793 μg/L (SW) and 0.021-0.203 μg/L (GW). Overall, this study quantified the NPs in complex aquatic environments for the first time, filling in gaps in our knowledge about NP pollution levels and providing a useful methodology and important reference data for future research.

Microwave-Assisted Extraction for Quantification of Microplastics Using Pyrolysis-Gas Chromatography/Mass Spectrometry

Microplastics are now recognized as a persistent and global pollutant. To quantitively measure microplastics in environmental matrices, several techniques are used including new methods using pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). In the present study, a new extraction method using microwave-assisted extraction (MAE) combined with Py-GC/MS was developed to extract and quantify a wide range of plastic polymers, and the method was validated using different environmental matrices. This new extraction method was able to extract polyethylene, polystyrene, polypropylene, poly(methyl-methacrylate) (PMMA), polyvinylchloride (PVC), and polycarbonate in dichloromethane with good recoveries (92.9-119.7%). The limit of detection and limit of quantification (LOQ) of the method ranged from 0.002 to 0.18 µg and from 1.2 to 5.8 µg, respectively. Intra- and interday repeatability values with coefficients of variation less than 25% for all polymers were obtained. Method validation also included a spike and recovery using all polymers from clean water, dirty water, and shrimp and salmon fillet samples, with recoveries of 85 to 111, 87 to 138, 81 to 122, and 50 to 151%, respectively. Finally, the method was tested on unspiked wild mussels and bottled water for proof-of-concept. Both polyethylene and PVC were detected and quantified in mussels, and polycarbonate and polypropylene were detected below the LOQ. For bottled water, polypropylene, polystyrene, and polycarbonate were all detected below the LOQ. We introduce a method combining MAE and Py-GC/MS as a tool for mass quantification of microplastics. This method can be used as a stand-alone, or as a complementary method to spectroscopic techniques. Environ Toxicol Chem 2021;40:2733-2741. © 2021 SETAC.

Effects of Water and Chemical Solutions Ageing on the Physical, Mechanical, Thermal and Flammability Properties of Natural Fibre-Reinforced Thermoplastic Composites

Biocomposites comprising a combination of natural fibres and bio-based polymers are good alternatives to those produced from synthetic components in terms of sustainability and environmental issues. However, it is well known that water or aqueous chemical solutions affect natural polymers/fibres more than the respective synthetic components. In this study the effects of water, salt water, acidic and alkali solutions ageing on water uptake, mechanical properties and flammability of natural fibre-reinforced polypropylene (PP) and poly(lactic acid) (PLA) composites were compared. Jute, sisal and wool fibre- reinforced PP and PLA composites were prepared using a novel, patented nonwoven technology followed by the hot press method. The prepared composites were aged in water and chemical solutions for up to 3 week periods. Water absorption, flexural properties and the thermal and flammability performances of the composites were investigated before and after ageing each process. The effect of post-ageing drying on the retention of mechanical and flammability properties has also been studied. A linear relationship between irreversible flexural modulus reduction and water adsorption/desorption was observed. The aqueous chemical solutions caused further but minor effects in terms of moisture sorption and flexural modulus changes. PLA composites were affected more than the respective PP composites, because of their hydrolytic sensitivity. From thermal analytical results, these changes in PP composites could be attributed to ageing effects on fibres, whereas in PLA composite changes related to both those of fibres present and of the polymer. Ageing however, had no adverse effect on the flammability of the composites.

Polypropylene structure alterations after 5 years of natural degradation in a waste landfill

Up to 25% of plastic waste in Europe is still disposed of in landfills, despite recycling efforts. The plastic waste in the landfill plot may be exposed both to abiotic and biotic degradation processes, although it is thought that most of the plastic materials tend to be resistant to biodegradation or biodeterioration even after a long time. To verify if polypropylene (PP) can undergo the process of short-term biodegradation and how this process is manifested in a municipal waste landfill, we collected a plastic sample from an already closed landfill plot estimating its age at approximately 5 years. Fourier-Transform Infrared Spectroscopy led to sample identification as PP as well as showed additional bands which are not specific to polymer structure but rather result from microbial metabolism. Differential Scanning Calorimetry was performed to examine the influence of the environmental degradation process on the degree of crystallisation of the tested PP. Moreover, significant changes on the surface of an old PP packaging were observed with Scanning Electron Microscopy (SEM) showing clear signs of PP delamination which resulted in microplastic particles formation (smaller than 5 μm in diameter). Additionally, several round and oval shaped structures were observed with SEM leading to the suspicion of biofilm formation on the PP surface. Indeed, the microorganisms were present in a vast amount on the old PP surface and possibly formed a viable biofilm as it was confirmed with fluorescence microscopy. These data show that plastic waste can be inhabited by microorganisms from the ambient environment which may probably lead to its faster degradation. However, this process should be investigated in more detail in order to shed light upon the possible risk factors of plastic biodegradation in waste landfills to the environment and human health. Even after five years, polypropylene can undergo deterioration/biodegradation in a waste landfill with viable microbial cells on its surface, possibly involved in its degradation.

Microplastics in wastewater outlets of Bandar Abbas city (Iran): A potential point source of microplastics into the Persian Gulf

Wastewater discharge is considered to be a significant point source of microplastic (MPs) release into the marine environment. This study is the first attempt to quantify MPs released from the wastewater outfall from Bandar Abbas City into the Persian Gulf. Two wastewater discharge stations at Gursuzan and Suru were sampled. MPs were isolated by an oxidative procedure and subsequent density separation using ZnCl₂ solution. The average MP concentration in wastewater and sludge were 70.66 (±14.12, SD) MP.35 L^-1 and 6070 (±807.25) MPs.kg^-1, respectively at Confidence Level (CL) (95.0%). The most commonly recovered polymers were polyethylene (PE) and polypropylene (PP) in all size classes. Our findings provides a baseline of MP concentration in wastewater streams and slurry that is discharged from the Bandar Abbas wastewater treatment facility into the Persian Gulf. This highlights the need to undertake more studies at water treatment plants in the region for a realistic assessment of MP discharge into the Persian Gulf.

Occurrence and distribution of microplastics in China's largest freshwater lake system

Although microplastics (MPs; < 5 mm) have been recognized as one of the most challenging environmental pollutants in the ocean, our understanding of the environmental fate of freshwater MPs falls far behind, particularly on smaller MPs (<0.1 mm). Here, we seek to reveal the latest MP pollution status in the largest freshwater lake of China, Poyang Lake, by comprehensively assessing the abundance, distribution, size, shape, polymer composition, and micro-morphology of MPs in water and sediment, covering a large geographic area of the Lake and its five main river tributaries. High levels of MPs were detected in water (up to 1064 ± 90 MP/m³) and sediment (up to 1936 ± 121 MP/kg), with the highest concentrations in the Gan River and the lowest in the national Nature Reserves. While a positive correlation was identified between MP abundance in water and sediment, the size distribution of MPs in between water and sediment was distinct. The dominant MP form in sediment and water was fragment and fiber, respectively. Infrared spectroscopy analysis confirmed the dominant polymer types including polypropylene, polyvinyl chloride, polyethylene, polystyrene, and polyvinyl alcohol. Moreover, both μ-FTIR and SEM results suggested significant features of weathering and fragmentation of MPs. This study provides comprehensive data to understand the environmental behavior and pollution magnitude of MPs in China's largest freshwater lake and highlights the significant contribution of smaller-size fractions (0.03-0.1 mm) to improve future MP studies in freshwater systems.

Current research and perspective of microplastics (MPs) in soils (dusts), rivers (lakes), and marine environments in China

In this study, we first reviewed the current research progress regarding the presence of environmental microplastics (MPs) in environment in China from 2010 to 2019. Results showed that: (1) current research has primarily focused on river and marine environments rather than soils and dusts, mainly located in eastern China, i.e., the Yangtze river, Poyang lake, Dongting lake, Yellow sea, and Bohai sea; (2) the abundance of MPs found in water bodies (sediments) of the rivers in China ranged from 3.9 to 7900 items·m^-3 (19.0 × 10³-13600.5 × 10³ items·km^-2), and 20-24300 items·kg^-2 (170-5500 × 10⁶ items·km^-2) in the sediments, respectively; in lake water the range was 340-8900 items·m^-3 (5 × 10³-340 × 10⁵ items·km^-2) and 8 to 1200 items·m^-2/25-300 items·kg^-1 in the sediments, respectively; in marine water the range was 0.003-540 items·m^-3 (0-380,100 item·km^-2) and 1.3-14700 item·kg^-1 in the sediments, respectively; in fish, shellfish, and natural planktons from ocean and freshwater, the range was 0-57 items·individuals^-1 (0-168 items·g^-1); (3) The absorption and toxicological effects of MPs in freshwater and oceans have mainly focused on polyethylene (PE), polypropylene (PP), and polystyrene (PS); (4) the sources of microplastics in soils and dusts primarily come from urban/town activities; for rivers and lakes (estuary), they primarily come from urban activities; for coastal waters, fishing gear and nets, and the maritime activities were the main sources.

Microplastic contamination of drinking water: A systematic review

BACKGROUND

Microplastics (MPs) are omnipresent in the environment, including the human food chain; a likely important contributor to human exposure is drinking water.

OBJECTIVE

To undertake a systematic review of MP contamination of drinking water and estimate quantitative exposures.

METHODS

The protocol for the systematic review employed has been published in PROSPERO (PROSPERO 2019, Registration number: CRD42019145290). MEDLINE, EMBASE and Web of Science were searched from launch to the 3rd of June 2020, selecting studies that used procedural blank samples and a validated method for particle composition analysis. Studies were reviewed within a narrative analysis. A bespoke risk of bias (RoB) assessment tool was used.

RESULTS

12 studies were included in the review: six of tap water (TW) and six of bottled water (BW). Meta-analysis was not appropriate due to high statistical heterogeneity (I2>95%). Seven studies were rated low RoB and all confirmed MP contamination of drinking water. The most common polymers identified in samples were polyethylene terephthalate (PET) and polypropylene (PP), Methodological variability was observed throughout the experimental protocols. For example, the minimum size of particles extracted and analysed, which varied from 1 to 100 μm, was seen to be critical in the data reported. The maximum reported MP contamination was 628 MPs/L for TW and 4889 MPs/L for BW, detected in European samples. Based on typical consumption data, this may be extrapolated to a maximum yearly human adult uptake of 458,000 MPs for TW and 3,569,000 MPs for BW.

CONCLUSIONS

This is the first systematic review that appraises the quality of existing evidence on MP contamination of drinking water and estimates human exposures. The precautionary principle should be adopted to address concerns on possible human health effects from consumption of MPs. Future research should aim to standardise experimental protocols to aid comparison and elevate quality.

Microplastics in Salt of Tuticorin, Southeast Coast of India

Microplastics (< 5 mm) are considered to be global environmental pollutants. This study investigates the occurrence, physical properties, polymer composition and surface morphology, and element composition of MPs present in food-grade salts produced from seawater and bore-well water in Tuticorin, Tamil Nadu, Southeast coast of India. Fourteen different brands of sea salts and bore-well salts were collected from the salt manufacturing units. The mean abundance of microplastics was 35 ± 15 to 72 ± 40 items/kg in sea salt and 2 ± 1 to 29 ± 11 items/kg in bore-well salt. Four types of polymers viz. polyethylene (51.6%), polypropylene (25%), polyester (21.8%), and polyamide (1.6%) were found in salt. Polyethylene fibers of size ranging from 100 to 500 µm were observed commonly. Being manufactured from seawater, sea salt had the highest quantities of different microplastic particles. The study reveals that people consume approximately 216 particles of MPs per year via sea salt and 48 items per year via bore-well salt if the average person has a daily salt intake of 5 g. The surface morphology of MPs as exhibited in the SEM-EDAX images obtained in the study revealed the different weathering features of MPs, such as pits, cracks, and particles adhering to the surface. The presence of the elements Fe, As, and Ni on the surfaces as identified by energy-dispersive x-ray spectroscopy indicates that these elements exist in the environment as contaminants and have become associated with the MPs. The trace metals adsorbed onto MPs increase the risks of human exposure and may cause some adverse effects in humans.

Exploitation of nitric oxide donors to control bacterial adhesion on ready-to-eat vegetables and dispersal of pathogenic biofilm from polypropylene

BACKGROUND

Nitric oxide (NO) donors have been used to control biofilm formation. Nitric oxide can be delivered in situ using organic carriers and acts as a signaling molecule. Cells exposed to NO shift from biofilm to the planktonic state and are better exposed to the action of disinfectants. In this study, we investigate the capability of the NO donors molsidomine, MAHAMA NONOate, NO-aspirin and diethylamine NONOate to act as anti-adhesion agents on ready-to-eat vegetables, as well as dispersants for a number of pathogenic biofilms on plastic.

RESULTS

Our results showed that 10 pM molsidomine reduced the attachment of Salmonella enterica sv Typhimurium 14 028 to pea shoots and coriander leaves of about 0.5 Log(CFU/leaf) when compared with untreated control. The association of 10 pmol L-1 molsidomine with 0.006% H2 O2 showed a synergistic effect, leading to a significant reduction in cell collection on the surface of the vegetable of about 1 Log(CFU/leaf). Similar results were obtained for MAHMA NONOate. We also showed that the association of diethylamine NONOate at 10 mmol L-1 and 10 pmol L-1 with the quaternary ammonium compound diquat bromide improved the effectiveness of biofilm dispersal by 50% when compared with the donor alone.

CONCLUSIONS

Our findings reveal a dual role of NO compounds in biofilm control. Molsidomine, MAHMA NONOate, and diethylamine NONOate are good candidates for either preventing biofilm formation or dispersing biofilm, especially when used in conjunction with disinfectants. Nitric oxide compounds have the potential to be developed into a toolkit for pro-active practices for good agricultural practices (GAPs), hazard analysis and critical control points (HACCP), and cleaning-in-place (CIP) protocols in industrial settings where washing is routinely applied. © 2020 Society of Chemical Industry.

Comparative study of the influence of linear and branched alkyltrichlorosilanes on the removal efficiency of polyethylene and polypropylene-based microplastic particles from water

Microplastics are a global environmental pollution. Due to this fact, new solutions are needed to reduce the amount in various aquatic environments. A new concept introduced by Herbort and Schuhen from the year 2016 describes the agglomeration of microplastics in water using silicon-based precursors. In the study presented here, alkyltrichlorosilanes with different linear and branched alkyl groups and a chain length between 1 and 18 carbon (C-) atoms are investigated for their suitability to fix microplastics (mixtures of polyethylene (PE) and polypropylene (PP)) and to form larger agglomerates. As the alkyl group has a major influence on the reaction rate and agglomeration behavior, we present here the extensive data collection of the evaluation of the best case. The removal efficiency is determined gravimetrically. The reaction behavior and the fixation process are characterized by hydrolysis kinetics. ²⁹Si-MAS-NMR spectroscopy, IR spectroscopy, and thermogravimetry (TGA) are used to characterize the chemical composition of the agglomerates. Finally, the use of optical coherence tomography (OCT) allows the visualization of the formed agglomerates. The results show that the different alkyl groups have a strong impact on the suitability of the alkyltrichlorosilanes for the agglomeration, as they influence the hydrolysis and condensation kinetics in water and the affinity to the microplastics. Best suited for microplastic removal were intermediate chain length between 3 and 5 C-atoms.

Occurrence and Spatial Distribution of Microplastics in the Surface Waters of Lake Naivasha, Kenya

Microplastics are emerging threat contaminants that have been shown to provide toxic pollutants, either from the environment or from their inherent toxic monomers and additives, a pathway into the aquatic food web. In the present study, the occurrence, abundance, and composition of microplastic load in the surface water of Lake Naivasha (Kenya) was determined. The surface water physicochemical parameters were measured in situ; microplastic samples were collected using plankton net trawls and treated with H₂ O₂ to decompose organic matter. The microplastic particles recovered were classified both by visual observation and by attenuated total reflection-Fourier transform infrared spectroscopy. The average microplastic concentration range in surface water was 0.183 ± 0.017 to 0.633 ± 0.067 particles/m² , with the mean concentration being 0.407 ± 0.135 particles/m² . Fragments, fibers, and films were identified and were mostly composed of polypropylene, polyethylene, and polyester. We also performed correlational analysis, which showed a strong positive association between microplastic quantity and turbidity, total nitrogen, and total phosphorus in the lake. The high variability in microplastic densities exhibited between the sampled locations was attributed to human activities, water and wastewater intake through rivers and tributaries, and the presence of local wind patterns responsible for the general water circulation. Our assessment adds to the growing documentation of microplastic presence in freshwater ecosystems, and provides a baseline for future monitoring and assessment in sediment and biota of Lake Naivasha and other Kenyan freshwater systems. Environ Toxicol Chem 2020;39:765-774. © 2020 SETAC.

Microplastic pollution in vegetable farmlands of suburb Wuhan, central China

Microplastic pollution has become an emergency issue in the global environment. However, little is known about the occurrence and distribution of microplastics in agroecological system. In this study, we investigated the pollution of microplastics in vegetable farmlands in suburb of Wuhan, central China. Results showed that the abundance of microplastics ranged from 320 to 12,560 items/kg_dw. Microplastic pollution adjacent to the suburban roads was about 1.8 times as serious as that in the residential areas. Microplastics with size less than 0.2 mm were dominated, reaching 70% in total. The main types of microplastics were fibers and microbeads. Moreover, polyamide (32.5%) and polypropylene (28.8%) were the main types of polymer. This study proclaims the occurrence and characteristics of microplastic pollution in typical farmland soils of suburb land. It may provide significant basis for subsequent research about microplastics contaminant in the terrestrial ecosystem.

Occurrence, distribution and size relationships of plastic debris along shores and sediment of northern Lake Victoria

Plastic pollution has been reported in sediment, surface water and biota of freshwater systems especially in Europe, North and South America, and Asia with limited studies focussing on African great lakes. This study therefore investigated the occurrence, abundance and distribution of micro-, meso- and macro-plastic debris along shores and sediment of northern Lake Victoria. The abundance of micro-, meso- and macro-plastics measured as particles/kg dry sediment were in range of 0-1102, 0-218 and 0-100 respectively in shoreline sediment and 0-108, 0-33 and 0-77 respectively in lake sediment. The mean abundance of micro-, meso- and macro-plastic debris at fish landing beaches (75.2 ± 50.0, 16.7 ± 8.1 and 18.1 ± 4.6 respectively) were higher than what was recorded at recreational beaches (1.5 ± 0.6, 3.1 ± 3.1 and 3.8 ± 3.8 respectively). Similarly, mean abundance of micro-, meso- and macro-plastic debris in lake sediment were higher in areas of fish landing beaches (9.5 ± 2.6, 2.1 ± 1.5 and 7.7 ± 4.5 respectively) than what was recorded in areas of recreational beaches (0.7 ± 0.7, 0.2 ± 0.1, and 0 ± 0 respectively). Films, filaments, fragments, foam and pellets were the plastic types, with the shoreline sediment dominated by films (>54%) while lake sediment was dominated by filaments (>55%), across size groups (micro-, meso- and macro-plastics). Spearman's rank correlation indicated strong and significant correlation between abundance of micro- and meso-plastics for total plastic, film plastic and fragment plastic in shoreline sediment. Significant correlation between macroplastics in shoreline sediment and microplastics in lake sediment for total plastics was observed. The FTIR analysis revealed that polyethylene, polypropylene, Polyethylene Terephthalate, Polyamide (nylon), and polyvinyl chloride were the major polymers. These results demonstrated that fish landing beaches along Lake Victoria are hotspot areas for plastic pollution of the lake and should therefore be targeted for management of plastic pollution of Lake Victoria.

Distribution and Characterization of Microplastics in Surface Waters and the Southern Caspian Sea Coasts Sediments

The Caspian Sea is the largest enclosed aquatic ecosystem in the world. The combinations of the toxic pollutants with microplastics endanger the Caspian Sea ecosystem. In this work, the distribution of microplastics was studied in surface waters and southern Caspian Sea coasts sediments. The samples were collected from eight stations, including the Tonakabon, Chalos, Nowshahr, Noor, Mahmood Abad, Babolsar, Sari, and Neka coasts. The average concentrations of microplastics in the coastal waters and sediments were 34,490 particles per km² and 210 particles per kg, respectively. Isolated microplastics were characterized using ATR-FTIR and energy dispersive X-ray (EDS) techniques. The samples exhibited a strong carbon peak in the EDS spectra, which was screened as microplastic particles. The microplastics were mainly fragments and foams and identified as polyethylene, polypropylene, and polystyrene by means of ATR-FTIR spectra. This is the first study to determine the distribution of microplastics in southern Caspian coastal regions.

Massive plastic pollution in a mega-river of a developing country: Sediment deposition and ingestion by fish (Prochilodus lineatus)

The aim of this study was to determine the amount, composition and origin of plastic debris in one of the world largest river, the Paraná River in Argentina (South America), focusing on the impact of urban rivers, relationships among macro, meso and microplastic, socio-political issues and microplastic ingestion by fish. We recorded a huge concentration of macroplastic debris of domestic origin (up to 5.05 macroplastic items per m²) dominated largely by bags (mainly high- and low-density polyethylene), foodwrapper (polypropylene and polystyrene), foam plastics (expanded polystyrene) and beverage bottles (polyethylene terephthalate), particularly downstream from the confluence with an urban stream. This suggests inadequate waste collection, processing and final disposal in the region, which is regrettably recurrent in many cities of the Global South and Argentina in particular. We found an average of 4654 microplastic fragments m^-2 in shoreline sediments of the river, ranging from 131 to 12687 microplastics m^-2. In contrast to other studies from industrialized countries from Europe and North America, secondary microplastics (resulting from comminution of larger particles) were more abundant than primary ones (microbeads to cosmetics or pellets to the industry). This could be explained by differences in consumer habits and industrialization level between societies and economies. Microplastic particles (mostly fibres) were recorded in the digestive tract of 100% of the studied Prochilodus lineatus (commercial species). Contrary to recently published statements by other researchers, our results suggest neither macroplastic nor mesoplastics would serve as surrogate for microplastic items in pollution surveys, suggesting the need to consider all three size categories. The massive plastic pollution found in the Paraná River is caused by an inadequate waste management. New actions are required to properly manage waste from its inception to its final disposal.