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The Mississippi River System is of great ecological and economic importance, making it crucial to monitor contaminants within it. While nutrient pollution is well studied, there are little data on microplastics (MPs) in the Mississippi River System (MSRS), especially during drought conditions. Herein, we characterize MP pollution from seven sites across the MSRS during both flash drought and non-drought periods using FTIR microspectroscopy (µ-FTIR). Additionally, we evaluate the impact of multiple water level conditions on MP polymer composition across five time points at a single sampling site. Of all MPs identified, polyethylene terephthalate (PET, 22%), resin (17%), and polyethylene (PE, 10%) were the most abundant polymers. Average concentrations ranged from 16 to 381 MPs/L across seven sites, with no significant difference in concentration between conditions. Irregular particles were the most common morphology, with most MPs falling in the lowest size range measured (30–100 μm). Drought condition had a significant (p < 0.001) impact on polymer composition, and polymers most strongly correlated with flash drought were mostly fluoropolymers. For the single sampling site, concentrations differed, but not significantly, across the five timepoints. These results demonstrate the complex relationship between MP concentration and drought condition, and also highlight the importance of fully characterizing MPs in environmental studies.
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Microplastics in Atlantic Ribbed Mussels (Geukensia demissa) from the Delaware Inland Bays, USA
Due to the prevalence of plastic pollution in coastal ecosystems, aquatic organisms are at high risk for accumulating microplastics (MPs). Filter-feeding bivalves, such as mussels and oysters, may be exposed to, and subsequently accumulate, MPs due to the high volume of water they pass through their bodies. This study assessed the levels of MPs within Atlantic ribbed mussels (Geukensia demissa), a common filter feeder found along the United States Atlantic Coast, from 12 sites within Rehoboth Bay, Indian River Bay, and Little Assawoman Bay, collectively known as the Delaware Inland Bays. Composited mussels from each site were digested using potassium hydroxide and filtered. Microplastics were physically identified, sorted based on color, and counted using a digital microscope. Microplastics, almost entirely dominated by synthetic microfibers, were found in all mussels well above laboratory blanks. Across all sites, 40% of microfibers were black, and 27% of fibers were clear. The composite concentrations of MPs ranged from 0.25 to 2.06 particles/g wet tissue, with a mean of 0.08 ± 0.06. In general, higher concentrations were found in mussels collected at sites that were adjacent to more urbanized land use versus those from rural sites. At two sites, individual mussels, in addition to composites, were analyzed and had MP concentrations ranging from 11 to 69 particles/mussel. This study represents the first evaluation of MPs in this ecologically important coastal species and suggests its viability as a biomonitoring species for microplastic pollution.
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- Award ID(s):
- 1757353
- PAR ID:
- 10513830
- Publisher / Repository:
- MDPI
- Date Published:
- Journal Name:
- Microplastics
- Volume:
- 3
- Issue:
- 1
- ISSN:
- 2673-8929
- Page Range / eLocation ID:
- 147 to 164
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3390/microplastics3010009
