Papers

61,005 results
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Article Tier 2

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

Researchers characterized microplastic pollution in sediments of four small-scale Japanese rivers, finding widespread contamination and identifying polymer types and potential sources, highlighting that even small river systems serve as microplastic transport pathways.

2021 The Science of The Total Environment 109 citations
Article Tier 2

Assessment of the sources and inflow processes of microplastics in the river environments of Japan

Researchers mapped microplastic concentrations across 29 Japanese rivers and found plastic particles present at 31 of 36 sampling sites. The concentrations were strongly linked to urbanization and population density, confirming that human activities in river basins are a major driver of freshwater microplastic pollution. The findings demonstrate that significant plastic fragmentation occurs before debris reaches the ocean, making rivers an important area for pollution monitoring.

2018 Environmental Pollution 514 citations
Article Tier 2

High-Resolution Mapping of Japanese Microplastic and Macroplastic Emissions from the Land into the Sea

Researchers developed a high-resolution method to map microplastic and macroplastic emissions from Japanese river catchments into the sea, using correlations between observed river concentrations and basin characteristics such as urban area ratio and population density to generate nationwide plastic emission estimates.

2020 Water 85 citations
Article Tier 2

Occurrence and distribution of plastic particles (10–25,000 μm) and microfibers in the surface water of an urban river network in Japan

This study assessed the occurrence and distribution of plastic particles (10-25,000 micrometers) and microfibers in the surface water of an urban river network in Japan, finding that plastic abundance was closely tied to urban land use and proximity to discharge points.

2023 Environmental Monitoring and Assessment 16 citations
Article Tier 2

Wastewater treatment plants elevating microplastic abundances, ecological risks, and loads in Japanese rivers: a source-to-sink perspective

A study of five rivers in Yamaguchi Prefecture, Japan found that wastewater treatment plant effluents significantly increased microplastic concentrations, types, and ecological risk scores in receiving rivers compared to upstream and rural waterways. The results confirm a source-to-sink pathway from treatment plants into rivers and ultimately coastal marine environments, highlighting that current treatment infrastructure is insufficient to prevent microplastic pollution.

2023 Environmental Science and Pollution Research 11 citations
Article Tier 2

Current Status and Issues of Microplastic Pollution Research

This Japanese review summarized microplastic research in river and ocean environments, including national estimates of plastic discharged from Japan's rivers to the sea and microplastic distribution in Tokyo Bay. The paper also reviewed current analytical methods and their limitations for measuring small microplastic particles.

2021 Journal of Japan Society on Water Environment 13 citations
Article Tier 2

Occurrence, distribution, and possible sources of microplastics in the surface river water in the Arakawa River watershed

Researchers investigated the occurrence, distribution, and potential sources of microplastics in surface river water along the Arakawa River watershed running through the Tokyo Metropolitan area, contributing to data on microplastic contamination in populated urban freshwater systems.

2021 Environmental Science and Pollution Research 38 citations
Review Tier 2

A Comprehensive Review of MP Pollution in Global Rivers: Distribution Patterns and Fluvial Transport Dynamics

A global review of microplastic pollution in river sediments found the highest concentrations in Africa and Asia, with wastewater treatment plants, industrial discharges, and urban runoff as the primary sources, and rivers transporting an estimated 70–80% of land-based plastic waste to the oceans. This synthesis underscores that rivers are critical intervention points for reducing the flow of microplastics into marine ecosystems.

2026 Water Environment Research
Article Tier 2

Occurrence, potential sources, and ecological risk assessment of microplastics in the inland river basins in Northern China

Researchers surveyed microplastic pollution in a typical urban river system in Northern China, examining both surface water and sediment samples. They found that river sediments contained dramatically more microplastics than surface water, acting as a sink for this pollution, with polypropylene and polyethylene being the most common types. The study suggests that small fiber and fragment-shaped particles under 0.5 mm dominate these environments, likely originating from everyday plastic products and wastewater discharge.

2024 Marine Pollution Bulletin 23 citations
Article Tier 2

Assessment of Small-Scale Microplastics Abundance and Characterization in Urban River: A Case Study in Metro River, Indonesia

Researchers assessed microplastic contamination in the Metro River in Indonesia, finding that abundance and characteristics varied by land use type, with urban areas showing higher concentrations of fragments and fibers in this rapidly developing region.

2023 Journal of Engineering and Technological Sciences 9 citations
Article Tier 2

Microplastics distribution, ecological risk and outflows of rivers in the Bohai Rim region of China - A flux model considering small and medium-sized rivers

Researchers assessed microplastic pollution across rivers flowing into the Bohai Sea in northern China, including smaller waterways that are often overlooked. They found that small and medium-sized rivers contributed nearly half of the total microplastic outflow to the sea, with Shandong province accounting for over 80 percent of the regional total. The study emphasizes that focusing only on major rivers significantly underestimates the true scale of microplastic transport into coastal waters.

2024 The Science of The Total Environment 7 citations
Article Tier 2

Microplastics in Freshwater River in Rio de Janeiro and Its Role as a Source of Microplastic Pollution in Guanabara Bay, SE Brazil

Researchers found widespread microplastic contamination in three rivers flowing into Guanabara Bay, Brazil, with an average of 3,651 particles per cubic meter dominated by fibers, identifying these freshwater systems as major sources of coastal microplastic pollution.

2023 Micro 40 citations
Article Tier 2

Microplastic pollution in sophisticated urban river systems: Combined influence of land-use types and physicochemical characteristics

This study assessed microplastic pollution across an urban river network in China, finding that land-use type and water physicochemical properties jointly influence microplastic distribution, with industrial and residential areas contributing highest loads.

2021 Environmental Pollution 50 citations
Article Tier 2

Microplastic pollution in aquatic environments with special emphasis on riverine systems: Current understanding and way forward

This review examines microplastic pollution in freshwater riverine systems, which serve as a critical link between terrestrial and marine environments. Researchers found that rivers are significantly contaminated with microplastics of varying sizes and morphologies, and that these particles can exhibit variable toxicity to aquatic organisms, highlighting the need for more research on freshwater microplastic impacts.

2021 Journal of Environmental Management 83 citations
Article Tier 2

Rapid Sampling of Suspended and Floating Microplastics in Challenging Riverine and Coastal Water Environments in Japan

Two newly developed compact sampling devices (Albatross Mark 5 and 6) collected microplastic samples from Japanese rivers and coastal waters in just 3 minutes compared to 10-60 minutes with conventional nets, while producing comparable concentration measurements. Polyethylene and polypropylene dominated, and particles became smaller from riverine to coastal environments.

2020 Water 56 citations
Article Tier 2

Knowledge about Microplastic in Mediterranean Tributary River Ecosystems: Lack of Data and Research Needs on Such a Crucial Marine Pollution Source

This review surveys the limited literature on microplastic pollution in freshwater rivers feeding the Mediterranean Sea, finding major gaps in data and inconsistent methods. The authors call for standardized monitoring protocols to better understand how rivers transport microplastics from land to the ocean.

2020 Journal of Marine Science and Engineering 42 citations
Article Tier 2

Evaluation of Micro- Nanoplastic Generation Potential in Class a River Basins Considering Population Distribution and Meteorogical Conditions

Researchers developed a grid-based model to evaluate micro- and nanoplastic generation potential in Class A river basins across Japan, applying degradation models from accelerated aging tests to population distribution, UV radiation, and rainfall data, finding the highest per-area potential in the densely populated Tsurumi River basin.

2025 Japanese Journal of JSCE
Article Tier 2

Microplastic pollution differences in freshwater river according to stream order: Insights from spatial distribution, annual load, and ecological assessment

Researchers compared microplastic pollution levels in a freshwater river across different land-use zones, finding higher concentrations near urban and agricultural areas than in forested regions. Fiber-type microplastics were predominant across all sampling locations.

2024 Journal of Environmental Management 5 citations
Article Tier 2

Mid-Level Riverine Outflow Matters: A Case of Microplastic Transport in the Jiulong River, China

Researchers found that the mid-sized Jiulong River in China exports substantial quantities of microplastics to coastal environments via riverine outflow, with sampling by both trawling and pumping methods revealing that smaller rivers are meaningful contributors to marine plastic loads.

2021 Frontiers in Marine Science 25 citations
Article Tier 2

Direkte Mikro- und Makroplastiktransportmessungen an großen und mittleren Flüssen sowie im Ablauf von Kläranlagen

This German-language study presents direct measurements of micro- and macroplastic transport in large and medium-sized rivers as well as wastewater treatment plant effluents. It addresses a research gap in freshwater plastic transport quantification, providing empirical data on how rivers carry plastics toward marine environments.

2020 Österreichische Wasser- und Abfallwirtschaft 2 citations
Article Tier 2

Quantifying annual microplastic emissions of an urban catchment: Surface runoff vs wastewater sources

Researchers measured the total annual microplastic emissions from an urban river catchment in Japan and compared contributions from wastewater treatment plants versus surface runoff. They found that the catchment released about 269 tons of microplastics per year, with wastewater being the dominant source for smaller particles and surface runoff contributing more larger particles. The study provides one of the first comprehensive annual budgets of urban microplastic emissions, highlighting the scale of the problem.

2024 Journal of Environmental Management 36 citations
Article Tier 2

Sources, Occurrence, and Analysis of Microplastics in Freshwater Environments

This review summarizes current knowledge on microplastic sources and occurrence in freshwater environments, noting that freshwater systems are major conduits delivering microplastics to the ocean. The review highlights that freshwater microplastic research lags far behind marine studies despite rivers and lakes being primary pollution pathways.

2022 6 citations
Article Tier 2

Microplastic pollution in two remote rivers of Türkiye

Researchers documented microplastic pollution in two remote rivers of Turkey, finding that even waterways far from major urban centers contain significant microplastic contamination, highlighting the widespread reach of plastic pollution in freshwater ecosystems.

2023 Environmental Monitoring and Assessment 31 citations
Article Tier 2

A multidimensional approach for microplastics monitoring in two major tropical river basins, Malaysia

Researchers conducted a multidimensional assessment of microplastic distribution in surface waters of two major Malaysian river basins, providing much-needed field data on microplastic emissions from Asian rivers known to be major contributors to ocean pollution.

2023 Environmental Research 43 citations