Assessing small-scale freshwater microplastics pollution, land-use, source-to-sink conduits, and pollution risks: Perspectives from Japanese rivers polluted with microplastics

Abundance, characteristics, and ecological risks of microplastics in the riverbed sediments around Dhaka city

<p>Freshwater microplastics pollution has been a recent focus. River freshwater microplastics pollution are vital towards freshwater ecosystems as well as have been the prominent source-to-sink conduits to export MPs into the marine realm. Wastewater treatment plants (WWTPs) have been identified as one of the major point-sources. To date, sources-to-sinks comprehensive knowledge are highly limited. This study explored sources-to-sinks microplastics pollution i.e., WWTPs-to-river-to-marine comprehensively. The two rivers i.e., Koya River (KR) and Nishiki River (NR) which are flowing to the Seto Inland Sea (SIS) and the WWTPs effluent samples were collected from selected (n=37) stations in the Yamaguchi prefecture, Japan. Filtration, wet peroxidation, and density separation methods were employed to extract microplastics particles. Polymers were identified via attenuated total reflectance-Fourier transform infrared spectroscopy. The average microplastics abundances were found KR—82.25±67.84 n/L and NR—38.73±24.13 n/L for the river water, and KRWWTPs—79.5±3.5 n/L and NRWWTPs—72.25±23.64 n/L for WWTPs effluents, respectively. The KR were found to be more polluted than the NR. WWTPs effluents were found posing higher abundances than rivers. Significantly higher microplastics concentration were found in the WWTPs downstream stations than other river stations. Characterization revealed that small MPs (<1000 µm) in size, fibers in shape, polymers— polyethylene, polypropylene, polyethylene terephthalate, vinylon were major in both of the WWTPs effluents and rivers. WWTPs influenced river environments by means both of the abundances and microplastics characteristics (shapes-size-polymers). The estimated source-to-sink emission demonstrated a substantial number of MPs discharge into the rivers by the WWTPs (0.007—0.086 billion/day) and rivers-to-SIS marine environments (1.15—7.951 billion/day). The emission represented that the WWTPs were the prominent point-source to cause river microplastics pollution. Rivers were the initial sinks of the Japan land-sourced microplastics and prominent pathways to emit microplastics to the ultimate marine sink i.e., SIS. Large amounts of MPs are being generated on land sources before the plastics wastes degrade into MPs secondarily. The pollution characteristics (shapes-sizes-polymers) indicated ecotoxicological threats to these rivers and the downstream environments. Overall, this study provided an insight of sources-to-sinks pollution, fulfilled the preliminary knowledge gaps of pollution occurring land-sources, fate and loadings. We recommended microplastics pollution control at source. This study will aid in developing microplastics pollution control and management strategies for environmental protection and sustainability in the regional Japan as well as global context upon “thinking globally and acting locally”.</p><p><strong>Keywords: </strong>Abundance, Point-source, Source-to-sink, Riverine microplastics pollution, Wastewater treatment plants</p>

Microplastics in the sediments of small-scale Japanese rivers: Abundance and distribution, characterization, sources-to-sink, and ecological risks

Un-protected open dug wells of shallow groundwater environments are subjected to high risk of chemical and microbial pollution in many parts of the world. The present study was initiated in Pungudutivu, one of the surrounding islands of the Jaffna Peninsula, Sri Lanka, because the island totally relies on its limited groundwater resources extracted from open dug wells to meet all its needs. The study assessed the risk of pollution within the limited fresh groundwater found in unconfined aquifer systems of Pungudutivu, where high risk of pollution was expected mainly from organic sources, derived from human and animal wastes and easy infiltration and runoff returns. The fresh groundwater pockets of Pungudutivu were however found to be with less serious contamination risks other than high Fe2+ and high faecal coliform counts. Low nitrate and phosphate concentrations with high COD and low BOD demonstrated less pollution from biodegradable organic sources in the midst of high oxidising potentials in the shallow dug wells as implied by the stability field of Fe(OH)3 on the Eh-pH diagram; the argument of high Fe2+ in groundwater however, wasn't supported by the said oxidation potential. High faecal coliform counts with high DO in groundwater probably indicated conditions implied by on site waste disposal in groundwater of Pungudutivu.

Microplastic pollution is a pressing environmental concern with detrimental effects on aquatic ecosystems and human health. This study aimed to investigate microplastic contamination in a rapidly urbanizing area along a river and to examine the spatial distribution of microplastic abundance across the study area based on land use type. Seven sampling points were selected along the study site and microplastic samples were extracted using density separation and wet peroxidation (WPO) methods. The characteristics of the microplastic particles, including size, color, shape, and abundance, were analyzed to understand their properties. The results indicated that the microplastic abundance values ranged from 28.33 to 133.00 particles/liter, with an average of 73.55 particles/liter. Small microplastic particles (SMP), with sizes ranging from 1 μm to 1 mm, along with fragment shapes, and clear colors were predominant in the study area. A generalized additive model was utilized to assess the relationship between land use and microplastic abundance. The model demonstrated a significant influence of built-up areas on the presence of microplastics (p-value < 0.05), with an r2 value of 0.76. Residential areas near the river were identified as the likely primary sources of the microplastics.

An enhanced risk assessment framework for microplastics occurring in the Westerscheldt estuary

Microplastics are ubiquitous pollutants in aquatic environments. To determine the microplastic pollution status of the Chishui River, the abundance, type, particle size, shape, ecological risk, and potential sources of microplastics were systematically studied using laser direct infrared (LDIR) technology. The results demonstrated that the abundance of microplastics in the surface water of the Chishui River ranged from 9.34 to 69.67 n/L, with an average abundance of 24.87 n/L. The three most abundant types of microplastics were polyethylene terephthalate (PET), polypropylene (PP), and polyamide (PA). The majority of microplastics were ≤50 μm in size, and most particles were fragmented. Pollution can originate from domestic garbage, sewage, and industries. The polymer hazard index (PHI), pollution load index (PLI), and pollution risk index (PRI) methods content of microplastics in the Chishui River Basin indicated a relatively light degree of pollution, and the overall risk level was deemed to be relatively low, with Polyvinylchloride (PVC) plastic being the main risk source. Thus, strengthening the control of plastics such as PVC is recommended to protect the ecological safety of rivers.

Global occurrence characteristics, drivers, and environmental risk assessment of microplastics in lakes: A meta-analysis

RETRACTED: Microplastic pollution in intertidal sediments along the coastline of China

Estuarine habitats are a critical zone of the Earth with strong land-sea interactions, that are strongly influenced by human activities. Microplastics (MPs) pollution in the Yellow River Delta (YRD) wetland, a typical young warm-temperate estuarine wetland, has not been comprehensively studied. The morphology, abundance, particle size, and polymer composition of MPs in the surface sediments of the YRD wetland were determined, and the pollution status and ecological risk in the study area were evaluated using the pollution load index (PLI) and potential pollution risk index (PRI). The results showed that the abundance of MPs in the YRD wetland was 20-520 n·kg-1, with a median value of 150 n·kg-1. The MPs were primarily fibers in shape and black in color, with particle size over 1 mm. The polymer components were primarily rayon, polyethylene, polyester, and polyethylene terephthalate. The PLI and PRI values of the MPs in the area were between 0.04-0.96 and 0.00-171.60, respectively, indicating that the pollution of MPs in the YRD wetland was at a slightly polluted level with low ecological risk.

Characteristics of soil microplastics and ecological risks in the Qilian Mountains region, Northeast Tibetan Plateau

Characterization and risk assessment of microplastics in laver from the Yueqing Bay

Modelling hydrogeological parameters to assess groundwater pollution and vulnerability in Kashan aquifer: Novel calibration-validation of multivariate statistical methods and human health risk considerations

Microplastics pollution and risk assessment in water bodies of two nature reserves in Jilin Province: Correlation analysis with the degree of human activity

Primary risk assessment of microplastic pollution in spineless cuttlefish (Sepiella inermis) from the North-East Bay of Bengal: A tissue-based analysis