Microplastic concentration, characterization, and size distribution in the Delaware Bay estuary.

Area of Science:

• Environmental Science
• Marine Biology
• Chemistry

Background:

• Estuaries are critical interfaces for understanding microplastic (MP) fate and transport in oceanic systems.
• Estuarine environments significantly influence the characteristics of plastic pollution, including size distribution and abundance.

Purpose of the Study:

• To quantify and characterize microplastic (MP) pollution, including size distribution, within the Delaware Bay estuary.
• To analyze polymer types and particle characteristics to inform environmental risk assessments.

Main Methods:

• Collected 31 samples from the Delaware River mouth to the coastal ocean across two campaigns (2019, 2022).
• Extracted MPs using wet peroxide oxidation and density separation; analyzed particles via Fourier transform infrared (FTIR) spectroscopy.
• Recorded color, morphology, and size dimensions for particles from 2022 samples.

Main Results:

• Identified 324 MPs out of 1015 analyzed particles, with concentrations ranging from below detection to 4.12 MP/m³.
• Polyethylene (53%) and polypropylene (43%) were the most abundant polymers; smaller MPs were prevalent at coastal ocean sites.
• Observed a correlation between total particles and plastic particles; higher MP concentrations were noted at frontal zones.

Conclusions:

• Microplastic pollution is present throughout the Delaware Bay estuary, with distinct polymer types and size distributions.
• Frontal zones may act as accumulation areas for microplastics and macroplastics.
• Findings provide crucial data for estuarine plastic pollution fate, transport, and risk assessments.