200 Microplastics in the Environment

Microplastics are becoming increasingly ubiquitous on Earth. This session aims to address: sources and distribution of microplastics globally, characterization and quantification of microplastic hazards and impacts throughout the microplastic life cycle, and mitigation of microplastics-induced health effects

Tuesday, 21 October 2025
1:30 PM - 5:30 PM
HBGCC, 213AB

Spatial Distribution of Surficial Microplastics in Sediments across the Mid-Atlantic, United States

Paper number: 200-7
Program: Technical Sessions
Time: 3:05 PM – 3:20 PM

Authors

Abstract

Most microplastics (MP), defined as particles within the size range from 1 μm to 5 mm, are generated through physical and biological degradation of larger plastic products. MP pollution is ubiquitous in both urban and rural areas in water, soil, sediment, and organisms. However, published data has not clarified the controls on MP distributed in freshwater sediment.  

This study aims to understand MP fate and transport by examining factors related to MP contamination across nine watersheds in the Northeastern, Mid-Atlantic, United States. We collected surface sediment samples from three watersheds and compiled data from previous publications for six additional watersheds in Pennsylvania, New Jersey, and New York. The watersheds ranged in size from approximately 170 km2 to 20,000 km2 and were located within the Oswego, larger Delaware, Susquehanna, and Allegheny River Basins. We explored the relationship between MP concentrations and various watershed characteristics such as land cover types, the number of wastewater treatment plants, and population densities.  

Similar to previous publications, we found a wide range of MP concentrations in sediment, ranging from 0 to ~3,000 particles kg-1. MP concentrations were generally consistent within the same watershed, but they differed across different watersheds. Interestingly, vegetation cover appeared to influence MP levels. Certain land cover types, such as grassland/herbaceous, shrub/scrub, and deciduous forest, were associated with higher MP concentrations in sediment of creeks and rivers. In contrast, evergreen forests, mixed forests, and higher Normalized Difference Vegetation Index (NDVI) values showed negative correlations with MP concentrations, as determined by correlation analysis. These findings suggest that vegetation may either facilitate the accumulation of MPs or act as a natural barrier, reducing MP contamination in freshwater river sediments. 

Geological Society of America Abstracts with Programs. Vol. 57, No. 6

doi: 10.1130/abs/2025AM-412149

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