The rapid increases in microplastics in urban lake sediments

Area of Science:

• Environmental Science
• Geology
• Materials Science

Background:

• Microplastics are a growing global pollutant, but historical data on their environmental presence is scarce.
• Determining the start of the Anthropocene is crucial due to human impact on Earth's systems.
• The potential of plastics as markers for the Anthropocene requires investigation.

Purpose of the Study:

• To establish a historical timeline of microplastic pollution using sedimentary records.
• To investigate the characteristics and origins of microplastics over time.
• To assess the suitability of microplastics as indicators for the Anthropocene.

Main Methods:

• High-resolution chronology using Cesium-137 (¹³⁷Cs), Lead-210 (²¹⁰Pb), and spherical carbonaceous particles (SCP).
• Analysis of sedimentary records from an urban lake in Wuhan city.
• Quantification and characterization of microplastics, including polymer type and surface features.

Main Results:

• Microplastic abundance in sediment increased significantly from 741 to 7707 items·kg^-1 over the past 60 years.
• Microplastics were predominantly fibers composed of polyester and rayon, suggesting textile origins.
• Older microplastics exhibited rougher surfaces with absorbed elements, indicating weathering and environmental interaction.

Conclusions:

• Microplastic pollution has dramatically increased in recent decades.
• Textile fibers are a major source of microplastic pollution.
• Microplastics show potential as 'fossils' or indicators for the Anthropocene, similar to other geological markers.