Microplastic distribution and characteristics across a large river basin: Insights from the Neuse River in North Carolina, USA

J Jack Kurki-Fox; Barbara A Doll; Bonnie Monteleone; Kayla West; Gloria Putnam; Liam Kelleher; Stefan Krause; Uwe Schneidewind

doi:10.1016/j.scitotenv.2023.162940

Microplastic distribution and characteristics across a large river basin: Insights from the Neuse River in North Carolina, USA

Sci Total Environ. 2023 Jun 20:878:162940. doi: 10.1016/j.scitotenv.2023.162940. Epub 2023 Mar 20.

Authors

J Jack Kurki-Fox¹, Barbara A Doll², Bonnie Monteleone³, Kayla West³, Gloria Putnam⁴, Liam Kelleher⁵, Stefan Krause⁶, Uwe Schneidewind⁵

Affiliations

¹ Biological and Agricultural Engineering, North Carolina State University, Raleigh, NC, USA. Electronic address: jjkurkif@ncsu.edu.
² Biological and Agricultural Engineering, North Carolina State University, Raleigh, NC, USA; North Carolina Sea Grant, North Carolina State University, Raleigh, NC, USA.
³ Plastic Ocean Project, Wilmington, NC, USA.
⁴ North Carolina Sea Grant, North Carolina State University, Raleigh, NC, USA.
⁵ School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, UK.
⁶ School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, UK; LEHNA - Laboratoire d'ecologie des hydrosystemes naturels et anthropises, University of Lyon, Villeurbanne, France.

PMID: 36934929
DOI: 10.1016/j.scitotenv.2023.162940

Abstract

While microplastics (MP) have been found in aquatic ecosystems around the world, the understanding of drivers and controls of their occurrence and distribution have yet to be determined. In particular, their fate and transport in river catchments and networks are still poorly understood. We identified MP concentrations in water and streambed sediment at fifteen locations across the Neuse River Basin in North Carolina, USA. Water samples were collected with two different mesh sizes, a trawl net (>335 μm) and a 64 μm sieve used to filter bailing water samples. MPs >335 μm were found in all the water samples with concentrations ranging from 0.02 to 221 particles per m³ (p m^-3) with a median of 0.44 p m^-3. The highest concentrations were observed in urban streams and there was a significant correlation between streamflow and MP concentration in the most urbanized locations. Fourier Transform Infrared (FTIR) analysis indicated that for MPs >335 μm the three most common polymer types were polyethylene, polypropylene, and polystyrene. There were substantially more MP particles observed when samples were analyzed using a smaller mesh size (>64 μm), with concentrations ranging from 20 to 130 p m^-3 and the most common polymer type being polyethylene terephthalate as identified by Raman spectroscopy. The ratio of MP concentrations (64 μm to 335 μm) ranged from 35 to 375, indicating the 335 μm mesh substantially underestimates MPs relative to the 64 μm mesh. MPs were detected in 14/15 sediment samples. Sediment and water column concentrations were not correlated. We estimate MP (>64 μm) loading from the Neuse River watershed to be 230 billion particles per year. The findings of this study help to better understand how MPs are spatially distributed and transported through a river basin and how MP concentrations are impacted by land cover, hydrology, and sampling method.

Keywords: Microplastics; Sampling method; Sediment; Streamflow; Urban development; Watershed.