Comprehensive analysis of spatial distribution of microplastics in Rawal Lake, Pakistan using trawl net and sieve sampling methods

Microplastics monitoring in freshwater systems: A review of global efforts, knowledge gaps, and research priorities

The escalating production of synthetic plastics and inadequate waste management have led to pervasive microplastic (MP) contamination in aquatic ecosystems. MPs, typically defined as particles smaller than 5 mm, have become an emerging pollutant in freshwater environments. While significant concern about MPs has risen since 2014, research has predominantly concentrated on marine settings, there is an urgent need for a more in-depth critical review to systematically summarize the current global efforts, knowledge gaps, and research priorities for MP monitoring in freshwater systems. This review evaluates the current understanding of MP monitoring in freshwater environments by examining the distribution, characteristics, and sources of MPs, alongside the progression of analytical methods with quantitative evidence. Our findings suggest that MPs are widely distributed in global freshwater systems, with higher abundances found in areas with intense human economic activities, such as the United States, Europe, and China. MP abundance distributions vary across different water bodies (e.g., rivers, lakes, estuaries, and wetlands), with sampling methods and size range selections significantly influencing reported MP abundances. Despite great global efforts, there is still a lack of harmonized analyzing framework and understanding of MP pollution in specific regions and facilities. Future research should prioritize the development of standardized analysis protocols and open-source MP datasets to facilitate data comparison. Additionally, exploring the potential of state-of-the-art artificial intelligence for rapid, accurate, and large-scale modeling and characterization of MPs is crucial to inform effective strategies for managing MP pollution in freshwater ecosystems.

In-situ detection of microplastics in the aquatic environment: A systematic literature review

Microplastics are ubiquitous in the aquatic environment and have emerged as a significant environmental issue due to their potential impacts on human health and the ecosystem. Current laboratory-based microplastic detection methods suffer from various drawbacks, including a lack of standardisation, limited spatial and temporal coverage, high costs, and time-consuming procedures. Consequently, there is a need for the development of in-situ techniques to detect and monitor microplastics to effectively identify and understand their sources, pathways, and behaviours. Herein, we adopt a systematic literature review method to assess the development and application of experimental and field technologies designed for the in-situ detection and monitoring of aquatic microplastics, without the need for sample preparation. Four scientific databases were searched in March 2023, resulting in a review of 62 relevant studies. These studies were classified into seven sensor categories and their working principles were discussed. The sensor classes include optical devices, digital holography, Raman spectroscopy, other spectroscopy, hyperspectral imaging, remote sensing, and other methods. We also looked at how data from these technologies are integrated with machine learning models to develop classifiers capable of accurately characterising the physical and chemical properties of microplastics and discriminating them from other particles. This review concluded that in-situ detection of microplastics in aquatic environments is feasible and can be achieved with high accuracy, even though the methods are still in the early stages of development. Nonetheless, further research is still needed to enhance the in-situ detection of microplastics. This includes exploring the possibility of combining various detection methods and developing robust machine-learning classifiers. Additionally, there is a recommendation for in-situ implementation of the reviewed methods to assess their effectiveness in detecting microplastics and identify their limitations.

Distribution patterns and environmental risk assessments of microplastics in the lake waters and sediments from eight typical wetland parks in Changsha city, China

The quality of water in urban parks is closely related to people's daily lives, but the pollution caused by microplastics in park water and sediments has not been comprehensively studied. Therefore, eight typical parks in the urban area of Changsha, China, were selected, and Raman spectroscopy was used to explore the spatial distributions and compositions of the microplastics in the water and sediments, analyze their influencing factors, and evaluate their environmental risks. The results showed that the abundances of surface water microplastics in all parks ranged from 150 to 525 n L-1, and the abundances of sediment microplastics ranged from 120 to 585 n kg-1. The microplastics in the surface water included polyethylene terephthalate (PET), chlorinated polyethylene (CPE), and fluororubber (FLU), while those in the sediments included polyvinyl chloride (PVC), wp-acrylate copolymer (ACR), and CPE. Regression analyses revealed significant positive correlations between human activities and the abundances of microplastics in the parks. Among them, the correlations of population, industrial discharge and domestic wastewater discharge with the abundance of microplastics in park water were the strongest. However, the correlations of car flow and tourists with the abundance of microplastics in park water were the weakest. Based on the potential ecological risk indices (PERI) classification assessment method, the levels of microplastics in the waters and sediments of the eight parks were all within the II-level risk zone (53-8,549), among which the risk indices for Meixi Lake and Yudai Lake were within the IV risk zone (1,365-8,549), which may have been caused by the high population density near the park. This study provides new insights into the characteristics of microplastics in urban park water and sediment.

Recent Study of Separation and Identification of Micro- and Nanoplastics for Aquatic Products

Micro- and nanoplastics (MNPs) are polymeric compounds widely used in industry and daily life. Although contamination of aquatic products with MNPs exists, most current research on MNPs focuses on environmental, ecological, and toxicological studies, with less on food safety. Currently, the extent to which aquatic products are affected depends primarily on the physical and chemical properties of the consumed MNPs and the content of MNPs. This review presents new findings on the occurrence of MNPs in aquatic products in light of their properties, carrier effects, chemical effects, seasonality, spatiality, and differences in their location within organisms. The latest studies have been summarized for separation and identification of MNPs for aquatic products as well as their physical and chemical properties in aquatic products using fish, bivalves, and crustaceans as models from a food safety perspective. Also, the shortcomings of safety studies are reviewed, and guidance is provided for future research directions. Finally, gaps in current knowledge on MNPs are also emphasized.

Litter per liter - Lakes' morphology and shoreline urbanization index as factors of microplastic pollution: Study of 30 lakes in NE Poland

Human activity and anthropopression play key roles in contaminating aquatic environments with microplastics (MPs). The lakes of northeastern Poland provide a wide range of freshwater ecosystems differing in morphology, hydrology and ecology. In this study, we investigate 30 lakes during summer stagnation, considering their varying levels of anthropogenization of the catchment area and taking into account increased tourist activity. MPs were found in each of the studied lakes in the range from 0.27 MPs/L to 1.57 MPs/L, and the average value was 0.78 ± 0.42 MPs/L. The features of the MPs were evaluated, including size, form and color (most frequent: 4-5 mm (35.0 %); fragments (36.7 %); blue (30.6 %), respectively). Gradual accumulation of MPs has been observed in the lakes that comprise the hydrological sequence. The amount of sewage produced by wastewater treatment plants was considered in the study area. Statistically significant differences were found between lakes with different surface areas and shoreline lengths, where lakes with the highest and smallest values were notably more polluted with MPs than lakes in the medium range (F = 34.64, p < .0001 and F = 5.96, p < .01, respectively). The study presents an easy-to-obtain shoreline urbanization index (SUI) that is particularly useful for lakes with heavily transformed catchments in terms of hydrology. A significant correlation between the MP concentration and SUI, reflecting the degree of direct catchment anthropopression (r = +0.4282; p < .05), was observed. The analysis of the human impact on shoreline conversions and development should also pique the interest of other researchers as a potential indicator of MP pollution.

Kıyı Lagün Sedimentlerinde Mikroplastiklerin Oluşumları ve Mekansal Dağılımları: Küçükçekmece Lagünü Örneği

Nehir, haliç ve lagünler, karasal ve deniz ekosistemleri arasında bağlantıyı sağlarken, tıpkı diğer kirleticilerde olduğu gibi sediment yapılarında da mikroplastik kirliliği hakkında kapsamlı bir profil ortaya koymaktadır. Bu çalışmada, Küçükçekmece Lagünü’nün üç farklı sucul alanından (deniz, kanal ve göl) alınan sediment örneklerinde mikroplastik bolluğu ve karakterizasyonunun belirlenmesi amaçlanmıştır. Bu kapsamda, lagünde belirlenen 5 istasyondan 12 aylık (Mart 2019 – Şubat 2020) sediment örnekleri alınmıştır. Mikroplastik ön işlemlerine tabi tutulan sediment örneklerinde, stereomikroskop ile mikroplastik bolluğu sayımı ve kategorizasyonu (boyut, tip ve renk) yapılmıştır. Ortalama mikroplastik bolluğu 2922,32±517,35 MP/kg olarak belirlenmiş olup, tespit edilen ortalama mikroplastik bolluğu değeri, ülkemizde daha önce yapılmış benzer çalışmalara kıyasla 2,4 kat daha yüksek bulunmuştur. Liflerin (%59) baskın mikroplastik tipi olduğu, baskın mikroplastik renginin siyah (%42) olduğu ve MP boyutlarının %50’sinin 1-100 μm arasında olduğu belirlenmiştir. Mevsimsel mikroplastik dağılımı irdelendiğinde ise, en yüksek bolluk değerlerinin yağışlı sezon olan kış aylarında olduğu tespit edilmiştir. Çalışma alanında en yüksek ortalama mikroplastik bolluğuna sahip L1 istasyonu, Küçükçekmece Lagünü Bağlantı Alanı temsil etmekte olup, lagündeki tüm antropojenik baskıların hissedildiği istasyon olarak ortaya çıkmaktadır. Bu çalışma, dünyanın diğer bölgelerindeki benzer sediment alanları için mikroplastik bolluğu ve dağılımı hakkında temsili veriler sağlamayı amaçlamaktadır.

Spatial analysis of the influence on "microplastic communities" in the water at a medium scale

The issue of microplastics in freshwater has been growing in concern. Besides their abundance, the characteristics of microplastics are also important issues. The concept of "microplastic communities" has been utilized to assess differences in microplastic characteristics. In this study, we utilized the "microplastic community" approach to evaluate the impact of land use on microplastic characteristics in water at a provincial scale in China. The abundance of microplastics in water bodies in Hubei Province varied between 0.33 items/L and 5.40 items/L, with an average of 1.74 items/L. Microplastics were significantly more abundant in rivers than in lakes and reservoirs, and their abundance was negatively correlated with the distance from the nearest residential district of sampling sites. Similarities of microplastic communities were significantly different in mountainous and plain areas. Anthropogenic surfaces increased microplastic abundance and tended to decrease the size of microplastics, whereas natural vegetation had the opposite effect. The effect of land use on microplastic community similarity was greater than that of geographic distance. However, spatial scale limits the effect of various factors on microplastic community similarity. This study revealed the comprehensive influence of land use on microplastic characteristics in water and emphasized the importance of spatial scale in the study of microplastic characteristics.

Ecological health risk assessment of microplastics and heavy metals in sediments, water, hydrophytes (Alternanthera philoxeroides, Typha latifolia, and Ipomoea carnea), and fish (Labeo rohita) in Marala wetlands in Sialkot, Pakistan

For the ecological risk assessment of heavy metals and microplastics in Marala wetlands in Sialkot, Pakistan, samples of sediments, water, aquatic plants (Alternanthera philoxeroides, Typha latifolia, and Ipomoea carnea), and fish (Labeo rohita) were studied from five different locations. Pb, Cd, and Cr concentrations were above permissible limits devised by WHO in sediments and water at most of sites. High concentrations of Cd were recorded in water samples compared to sediments with maximum values recorded at Site-2 (52.08 ± 9.55 mg kg-1) and Site-5 (62.29 ± 10.12 mg kg-1). The maximum concentrations of Cr (7.23 ± 0.40 mg kg-1) and Pb (22.87 ± 0.83 mg kg-1) were found at Site-4 in water samples. The maximum abundance of microplastics (3047 pieces kg-1 of sediments) was at Site-1 with filaments in the highest proportion among the other types. Zn, Ni, and Cu remained generally low in concentrations in both sediments and waters. Plants showed accumulation of heavy metals, notably the amount of Cd (33.36 ± 0.26 mgkg-1) and Ni (163.3 ± 1.30 mgkg-1) absorbed by T. latifolia and A. philoxeroides, respectively were high. Also, photosynthetic pigments in plants seemed to be affected. However, estimated daily intake (EDI) and provisional tolerable weekly intake (PTWI) calculations for the human population consuming fish from this wetland remained below the FAO/WHO limits. PCA analysis revealed the anthropogenic origin of metals that might be causing adverse effects on the biota which depend on this wetland for their food.

Impact of coastal wastewater treatment plants on microplastic pollution in surface seawater and ecological risk assessment

This study aims to understand the influence of wastewater treatment plant discharge on the microplastic status in the surface seawater of Istanbul. For this purpose, for the first time, the distribution, composition, and ecological risk of microplastics at nine sampling stations on the southern coast of Istanbul, Marmara, were investigated at monthly intervals over a one-year period. The results showed that the microplastic abundance ranged from 0 to over 1000 particles per liter. Fibers were the dominant form at all stations. Microplastics 249-100 μm were the dominant size, and transparency was the color most found at all stations. Polyethylene and ethylene-vinyl acetate were the major types of microplastics, accounting for 50% overall. The pollution load index revealed that over 70% of sampling stations were at hazard level I. However, the hazardous index was categorized as level III with a value of 662.3 due to the presence of the most hazardous polymer named polyurethane. Further investigations into the risk assessment of MP can reveal crucial knowledge for understanding the microplastic cycle.