Distribution and characterization of microplastics in beach sand from three different Indian coastal environments

Microplastics in the freshwater and terrestrial environments: Prevalence, fates, impacts and sustainable solutions

The ubiquitous occurrences of microplastics in the environment have raised much concern and resulted in voluminous studies related to microplastics. Studies on microplastics pollution of the marine environment have received significantly higher attention compared to those of the freshwater and terrestrial environments. With the impetus to better understand microplastics in the freshwater and terrestrial environments, this review elucidates the findings of >100 articles related to the prevalence, fates and impacts of microplastics therein and the sustainable solutions, mostly in the past 10 years. This review shows the interconnection between terrestrial and freshwater microplastics with wastewater and sewage treatment plants as the most significant contributors of environmental microplastics via sludge and effluent discharges. Microplastics in both ecosystems comprise the primary and secondary forms with the latter resulted from weathering of the former. Besides retaining in soil and infiltrating with rainwater underground, terrestrial microplastics also enter the freshwater environment. The environmental microplastics interact with the biotic and abiotic components resulting in entrainment, settlement, biofouling, degradation, fragmentation and entry into the food chain, with subsequent transfer across the food chain. The abundance of environmental microplastics is attributed to population density and urbanization though tidal cycle, storms, floods and human activities can affect their distribution. The leaching of additives from microplastics poses major health concern and sustainable solutions target at reduction of plastics use and disposal, substitution with bioplastics and wastewater treatment innovations. Further studies on classification, detection, characterization and toxicity of microplastics are necessary to permit more effective formulation of solutions.

Assessment of micro and macroplastics along the west coast of India: Abundance, distribution, polymer type and toxicity

Considering the magnitude of pollution caused by marine plastics, the present study assessed their abundance, distribution, surface morphology and polymer type in ten sandy beaches spread across three states (Maharashtra, Karnataka and Goa) along the west coast of India (WCI). The total abundance of plastics (∼1-100 mm) in the studied beaches ranged from 4.1 to 23.4% (19±1-346 ± 2 items/m²). Location-wise, the abundances of both micro (43.6 ± 1.1-346 ± 2 items/m²) and macroplastics (21.6±3-195 ± 6 items/m²) were relatively higher in beaches along the Maharashtra coast. Surface morphology-wise, fragments were predominantly abundant in both micro (76±2-346 ± 2 items/m²) and macroplastics (50.6 ± 1.5-195 ± 6 items/m²) followed by pellets (43.3 ± 2.5-245.6 ± 2 items/m²). Fourier-transform infrared spectroscopy (FT-IR) analysis of plastics revealed a dominance of polyethylene (PE) followed by polypropylene (PP). IR spectra of the collected plastics at absorption band at 1750-1700 cm^-1 reflect minimal surface oxidation. White-colored plastics were observed most frequently, followed by pale-yellow, dark-brown, green, blue, transparent and red. A short-term (72 h) experimental study to assess the toxicity of PE microbeads (∼1 mm) in a commercially important shrimp species, Litopenaeus vannamei revealed toxicological changes. An elevated level of lipid peroxidation (LPX)-the tagged biochemical marker, was recorded only at the maximum dose (0.15 mg/L) of PE microbeads. A moderate increase in the levels of enzymatic antioxidants (catalase and glutathione S-transferase) was also recorded at the same dose. Comprehensive information on marine plastics, including ecotoxicity provided in this study, would help in evolving strategies in minimizing plastic pollution along the WCI.

A critical viewpoint on current issues, limitations, and future research needs on micro- and nanoplastic studies: From the detection to the toxicological assessment

Increasing scientific attention on the presence of micro- and nanoplastics (MNPs) in the environments and their potential toxic effects on humans and the ecosystems is evident. Accordingly, the number of publications on this topic has increased substantially from only 5 in 2010 to more than 850 in 2019. Thus, this critical review aimed at providing state-of-the-art information on the existing methods for characterization and detection of MNPs in various matrices, as well as the reported toxic effects of MNPs in both in vivo and in vitro systems, anticipating challenges and providing future needs to improve the current scientific knowledge. We performed a systematic search of recent literature on available methodologies for the characterization/detection of MNPs in different samples, and the summary of such protocols is provided. Also, the existing procedures for in vitro and in vivo toxicity evaluation of MNPs were critically described. The results of our search revealed that quite a great deal of effort had been made to detect, characterize, and quantify the fate and effect of MNPs. However, we are still far from a complete understanding of behaviors of MNPs in the environments and biological systems. Thus, there is a need to advance the existing protocols to improve data accuracy. Besides, more studies that focus on uptake kinetics, accumulation, and biodistribution of MNPs in biological systems are required.

Abundance and distribution of microplastics on sandy beaches of Lima, Peru

Microplastic pollution is a problem of global scale, posing a threat to marine biota. To determine the current state of microplastic pollution on four popular sandy beaches of the coast of Lima, Peru, a sampling campaign was carried out in both intertidal and supralittoral zones. Microplastic abundance, type, size, color and distribution were recorded. The overall microplastic abundance was of the same order of magnitude as previous data obtained in Peru. Foams were the most abundant (78.3%) microplastic type. Statistical analyses revealed significant differences between sites and zones. High variability of microplastic abundance was found among adjacent beaches and zones. Fourier Transform Infrared Spectroscopy (FTIR) analysis revealed that all foams were identified as polystyrene. The present results revealed an alarming level of microplastics present on Peruvian sandy beaches, but information about the sources, local dynamics and impacts of microplastics in this region are scarce, and thus further research is needed.

Pollution Characteristics of Microplastics in Soils in Southeastern Suburbs of Baoding City, China

Microplastics (MPs) are emerging pollutants that exist in different environmental media. Because of their wide range and large potential environmental hazards, they have attracted widespread attention in recent years. At present, the research on MP is mostly concentrated on the water ecosystems, and the impact on soil ecosystems is less studied. In this study, 12 typical soil samples from southeastern suburbs of Baoding city were investigated and characterized by time-of-flight secondary ion mass spectrometry (TOF-SIMS) combined with mass high resolution mode and positive and negative ion imaging mode. Four types of MPs, poly (propylene) (PP), poly (vinyl chloride) (PVC), poly (ethylene terephthalate) (PET), and poly (amide 6) (PA6), were quickly identified, of which PET and PA6 accounted for the largest proportion of both up to 30.2%; the particle size of the obtained MPs ranged from 0 to 35 μm, of which the proportion of <10 μm MPs was more than 26.3%, while that of 20–25 μm and 25–35 μm MPs was relatively small (17.83% and 9.3%, respectively). Risk assessment results of the MP in the soil showed that the risk level of MPs in the non-ferrous metal industrial parks and in concentrated with small workshops areas is relatively high, and attention should be paid to such areas. In addition, the study provides a reference method for the investigation and risk assessment of MPs in terrestrial soils, coastal beaches, and sediments.

Continuous Adsorption Modeling and Fixed Bed Column Studies: Adsorption of Tannery Wastewater Pollutants Using Beach Sand

This study deals with the removal of residual pollutants from tanning wastewater by continuous adsorption mechanism, using local sand as a low-cost adsorbent. The possibility of pretreating a complex tannery effluent heavily loaded with a natural material such as sand is significant. The characterization of the adsorbent before and after continuous adsorption was performed by X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy. Column studies were also carried out to evaluate the performance of the adsorbent and the efficiency of column adsorption. The adsorption kinetic rate seems to be strongly influenced by certain parameters such as the particle size of the material used, the withdrawal rate of the influent and the height of the adsorbent bed, and optimized parameters were found to be 63 μm, 15 ml·min−1, and 7 cm, respectively, and the color removal has achieved maximum values which vary between 95 and 100%. The results suggest that sand can be used as an economical adsorbent for the removal of color from the wastewater of the tanning industries.

Ecological and toxicological manifestations of microplastics: current scenario, research gaps, and possible alleviation measures

Microplastics (MPs) and associated contaminants have become a major environmental concern. From available literature, their ubiquitous presence is now well established. However, the kind and level of toxicological impacts these MPs accomplish on various life forms are not well understood. Nevertheless, the environmental toxicity of MP is now being revealed gradually with supporting studies involving groups of lower organisms. Additionally, the presence of microplastics also disturbs the functions of ecosystem through affecting the vulnerable life forms, thus ecological manifestations of MPs also need to be analyzed. The present review encompasses an overview of toxicological effects mediated by various types of MPs present in the environment; it covers the types of toxicity they may cause and other effects on humans and other species. In this review, aquatic systems are used as primary models to describe various eco-toxicological effects of MPs. Various research gaps as well as methods to alleviate the level of MPs, and future strategies are also comprehensively highlighted in the review.

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.

Macrodebris and microplastics pollution in Nigeria: first report on abundance, distribution and composition

The abundance, distribution and composition of marine debris ( > 5 cm) and small microplastics (11 μm) from five rivers in South Eastern Nigeria was investigated. This study provided the first assessment of the type and quantity of marine litter and microplastics in Nigeria. A total of 3,487 macrodebris items/m² were counted with the following distribution: plastics (59%), metal (10%), cloth (7%), paper/cardboard (7%), rubber (7%), glass/ceramics (5%), medical and agro-based waste (3%), and wood (2%). The cleanliness of the river assessed with clean coast index ranged from “very clean” to “extremely dirty”. Microplastics abundance ranged from 440 to 1,556 particles/L, with high accumulation at downstream. Fragment shape was most abundant while fiber and film followed. The distribution of plastic types was PET (29%), PE (22%), PVC (16%), PP (14%), and others (6%). Significant relationship was found between the total abundances of microplastics and different macrodebris groups suggesting that microplastics were abundant in areas where the macrodebris abundance was high. Our results provide baseline information for future assessments. Management actions should focus on input prevention including proper waste management, recycling of plastics, and strict penalties for illegal dumping of wastes.

The impact of sediment dumping sites on the concentrations of microplastic in the inner continental shelf of Rio de Janeiro/Brazil

The marine environment is constantly being impacted by anthropogenic activities. Nowadays, microplastics (MPs) representing one of the most deleterious material among of all substances and material from anthropogenic origin. The Microplastics (MPs) are particles smaller than 5 mm. This study presents information on abundance, distribution, type and colour of microplastics in the bottom sediments of the continental Shelf of Rio de Janeiro State. This area is strongly impacted due to its location in front of one of the most polluted coastal bays in the Brazilian Coastline. It receives untreated sewage from an Ipanema Beach submarine emissary and also a great amount of sediments dredged from Rio de Janeiro Harbour, which strongly influences the distribution of MPs in the area. The analyses detected the presence of MP in 100% of the samples, composed mainly by secondary microplastics, and almost 50% were fibers, followed by plastic films, plastic fragments and pellets. Based on the nature of the sources of the MP, a great variety of colours was shown, dominated by four main colours: blue, white, transparent, and black, this pattern could potentially increase their bioavailability due to resemblance to prey items, especially to visual raptorial species.

The marine nano- and microplastics characterisation by SEM-EDX: The potential of the method in comparison with various physical and chemical approaches

The marine microplastic (MMs) is an interdisciplinary problem. The polymer debris are ubiquitous (soil, hydrosphere, atmosphere) and the majority ends, transported by the freshwaters, in the global ocean system: from pelagial waters, surface gyres and benthos up to the animals at different trophic levels. Their quantitative, qualitative and eco-toxicological analyses, based on analytical, physical and chemical methods, are still a challenge due to the complex matrices, materials weathering, limited concentration, and size. Moreover, further fragmentation due to the waves and UV radiation leads to the constant increase of their surface. The aim of this article is to present the advantages, drawbacks and future perspectives of using SEM-EDX method in the analyses of marine polymer debris from macro to the nanoscale. Theoretical issues are presented in comparison to the commonly used approaches. The practical aspects will be discussed based on case studies. Examples of the results, high-resolution SEM pictures are included.

Environmental implications of microplastic pollution in the Northwestern Pacific Ocean

Microplastics (MPs) contamination has been recognized as one of major threats to coastal marine environments. Although studies evidenced severe MPs contaminations to the Pacific Ocean, environmental implications of MPs concentrations, distributions, and characteristics have not been evaluated in sufficient detail. Here, we report on the distribution, abundance, and characteristics of MPs at the surface of the Northwestern Pacific Ocean, from which environmental implications are assessed. A manta trawl with a mesh size of ~330 μm and a rectangular net opening of 0.45 × 1 m was used to collect MPs samples on May 11-June 3, 2018. The MPs samples were sequentially isolated, digested, filtered, and characterized using an optical microscope, micro-Raman spectroscopy, and scanning electron microscopy. The results indicate the heterogeneity in abundance, shapes, color, and sizes of MPs. The study provides strong environmental implications such as sources, environmental degradation, residence time, transportation routes, and biological interactions.

Robust Automatic Identification of Microplastics in Environmental Samples Using FTIR Microscopy

The analysis of microplastics is mainly performed using Fourier transformation infrared spectroscopy/microscopy (FTIR/ μFTIR). However, in contrast to most aspects of the analysis process, for example, sampling, sample preparation, and measurement, there is less known about data evaluation. This particularly critical step becomes more and more important if a large number of samples has to be handled. In this context, it is concerning that the commonly used library searching is not suitable to identify microplastics from real environmental samples automatically. Therefore, many spectra have to be rechecked by the operator manually, which is very time-consuming. In this study, a new fully automated robust microplastics identification method is presented that assigns over 98% of microplastics correctly. The main concept of this new method is to detect and numerically describe the individual vibrational bands within an FTIR absorbance spectrum by curve fitting, which leads to a very compact and highly characteristic peak list. This list allows very accurate and robust library searching. The developed approach is based on the already published microplastics identification algorithm (μIDENT) and extends and improves the field of application to μFTIR data with a special focus on relevant broad, overlapped, or complex vibrational bands.

Abundance, characteristics and surface degradation features of microplastics in beach sediments of five coastal areas in Tamil Nadu, India

This study undertook to investigate the occurrence of microplastics (MPs) in the high and low-tide sediments of five coastal areas in Tamil Nadu, India. The abundance of microplastics vary from 439 ± 172 to 119 ± 72 (HTL) and 179 ± 68 to 33 ± 30 (LTL) items kg^-1 of sediments. The MP polymers found in the study sites are Polyethylene (73.2%), polypropylene (13.8%), nylon (8.2%), polystyrene (2.8%) and polyester (2%). The weathered surfaces might act as high-capacity carriers and this was confirmed by SEM-EDAX. The results of an analysis of the textures of the sediments do not ascribe any influence on microplastic abundance. The recreation, religious and fishing activities are the major contributors to plastic pollution in these beaches, which is borne out by the high abundance of MPs in the study sites. A regular and permanent waste management system should be put in place for the protection of beaches.