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Centennial records of small microplastics in the East China Sea: Temporal evolution and implication for sediment geochronology
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Scientists studying seafloor sediments near China's Yangtze River found that tiny plastic particles smaller than a human hair (under 100 micrometers) make up over 90% of all microplastics buried there — far more than earlier studies suggested, since older methods often missed these smallest pieces. This matters because it means we've likely been underestimating just how much microplastic pollution has built up in our oceans over the past century, and these ultra-small particles are exactly the size most easily taken up by marine life and, potentially, absorbed into our own bodies through the food chain.
Small microplastics are abundant in marine sediments but remain poorly resolved in long-term sedimentary records. Here, we used laser direct infrared imaging to quantify 20-500 μm microplastics in two dated sediment cores from the Yangtze River Estuary-East China Sea continuum. Particles <100 μm accounted for more than 90% of all detected microplastics in both cores, indicating that small microplastics dominate the sedimentary inventory and have likely been underestimated in previous records. The two cores showed distinct proximal-distal differences. The Zhejiang-Fujian coastal mud depocenter contained higher microplastic abundance than the Yangtze subaqueous delta, whereas polymer composition differed markedly, with polyurethane dominating the distal core and polyamide dominating the proximal core. These contrasts indicate that sedimentary microplastic burial is shaped by source-to-sink transport and depositional setting across the estuary-shelf continuum. The centennial records were divided into four stages: pre-1949, 1949-1980, 1980-2000, and post-2000. Stepwise increases and major inflection points broadly coincided with transitions in China's plastics industry, whereas pronounced post-2000 fluctuations likely reflect the basin-scale engineering activities and hydrodynamic disturbance. Although the first occurrence of microplastics is not a reliable isochronous marker, transitions in dominant polymer abundances provide useful complementary constraints for evaluating Pb/Cs-based sediment chronologies. These results demonstrate that small microplastics provide sensitive sedimentary records of anthropogenic activity and can improve centennial-scale interpretation of microplastic burial on river-dominated continental margins.
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Tracing the Anthropocene through microplastic sedimentary records: Drivers and spatiotemporal heterogeneity in Baiyangdian Lake, North China
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Scientists found that tiny plastic pieces in lake sediment can track how human activities have changed over the past 80 years, with plastic pollution spiking after dam construction in 1963 and again around 2000 due to increased development. The study shows that microplastics are now everywhere in our environment, even in protected nature areas, though at lower levels than in more developed zones. This matters because these tiny plastics can enter our food and water supply, and understanding where they accumulate most helps us better protect both ecosystems and human health.
Microplastics in Surface Water in the Yangtze River, China: Basin-Wide Observation, Multiple Ecological Risk Assessment and Sustainability
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Researchers conducted a three-year survey of microplastic pollution across the entire Yangtze River Basin in China and found an average of nearly 8,800 microplastic particles per cubic meter of surface water. Tiny particles smaller than 0.3 millimeters made up over 92% of what was found and drove the variation in pollution levels between locations. The study highlights that previous research may have significantly underestimated microplastic contamination by not capturing these smallest particles.
The pollution of microplastics in sediments of the Yangtze River Basin: Occurrence, distribution characteristics, and basin-scale multilevel ecological risk assessment
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This study mapped microplastic pollution throughout the Yangtze River Basin in China and found an average of 611 particles per kilogram of sediment, with wide variation across locations. Smaller microplastics under 1 millimeter and fibrous shapes were most common, and contamination was closely linked to population density and human activities. The findings are concerning because the Yangtze River system provides drinking water and food resources to hundreds of millions of people.
The rapid increases in microplastics in urban lake sediments
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Researchers used sediment cores from an urban lake in Wuhan, China, combined with high-resolution dating techniques, to track microplastic accumulation over the past 60 years. They found that microplastic abundance increased more than tenfold, from 741 to 7,707 items per kilogram, with fibers from textiles being the dominant type. The study suggests that microplastics could serve as geological markers of the Anthropocene era, similar to fossils in the sediment record.
Characteristics and Distribution of Microplastics in Shoreline Sediments of the Yangtze River, Main Tributaries and Lakes in China—From Upper Reaches to the Estuary
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Scientists measured microplastic concentrations in sediments along 54 sites spanning the Yangtze River system in China, from the upper reaches to the estuary. Microplastics were found throughout, with higher concentrations near urban and industrial areas, showing how large rivers distribute plastic pollution across vast distances.
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