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A portable toilet manufacturer in northwest Indiana (USA) released polyethylene microplastic (MP) pollution into a protected wetland for at least three years. To assess the loads, movement, and fate of the MPs in the wetland from this point source, water and sediment samples were collected in the fall and spring of 2021–2023. Additional samples, including sediment cores and atmospheric particulates, were collected during the summer of 2023 from select areas of the wetland. The MPs were isolated from the field samples using density separation, filtration, and chemical oxidation. Infrared and Raman spectroscopy analyses identified the MPs as polyethylene, which were quantified visually using a stereomicroscope. The numbers of MPs in 100 mL of the marsh water closest to the source ranged from several hundred to over 400,000, while the open water samples contained few microplastics. Marsh surface sediments were highly contaminated with MPs, up to 18,800 per 30.0 g dry mass (dm), compared to core samples in the lower depths (>15 cm) that contained only smaller MPs (<200 µm), numbering 0–480 per 30.0 g (dm). The wide variations in loads of MP contaminants indicate the influence of numerous factors, such as proximity to the point source pollution, weather conditions, natural matter, and pollution sinks, namely sediment deposition. As proof of concept, we demonstrated a novel remediation method using these real-world samples to effectively agglomerate and remove MPs from contaminated waters.
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This content will become publicly available on December 20, 2026
Vertical profiles of microplastics in coastal sediments of Panjang Island, Java Sea
The proliferation of plastic pollution has led to the widespread accumulation of microplastics (MPs) in marine ecosystems. While surface sediment contamination is relatively well studied, knowledge of vertical MP distri- bution within sediment columns remains limited. This study examines the abundance, vertical distribution, and characteristics of MPs in subtidal and intertidal sediments of Panjang Island, Java Sea. Fifteen shallow (10 cm) and three deep (~100 cm) sediment cores were analyzed for MP abundance, morphology, size, color, and polymer using microscopy and ATR-FTIR. MPs were detected in all cores, with an average concentration of 0.49 ± 0.28 MPs g⁻¹ in surface sediments. The highest surface concentration (2.08 ± 0.22 MPs g⁻¹) occurred in the southwest, a sheltered site with greater anthropogenic influence, while the lowest (0.05 ± 0.07 MPs g⁻¹) was recorded in the northwest, a remote and less disturbed area. Fibers dominated particle types. White, black, and blue were the most common colors, and size distributions were skewed toward particles <1 mm. Polypropylene and polyethylene were the most frequent polymers, reflecting their widespread use and persistence. Vertical profiles revealed higher MP concentrations near the surface, indicating intensified inputs in recent decades. No MPs were detected below 70 cm, suggesting limited downward migration and marking the onset of contami- nation during the plastic era. This study also found MPs in deeper sediment layer, likely due to post-depositional processes such as bioturbation. These findings demonstrate that sediment cores serve as valuable archives of historical MP deposition, capturing both global production trends and local environmental influences, and provide a basis for targeted management strategies.
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- Award ID(s):
- 2049567
- PAR ID:
- 10646791
- Editor(s):
- NA
- Publisher / Repository:
- Elsevievier
- Date Published:
- Journal Name:
- Regional Studies in Marine Science
- Volume:
- 91
- Issue:
- 104518
- ISSN:
- 2352-4855
- Page Range / eLocation ID:
- 1-10
- Subject(s) / Keyword(s):
- Microplastic pollution Sediment core Tropical island Vertical profile Historical microplastic
- Format(s):
- Medium: X Size: N/A Other: N/A
- Size(s):
- N/A
- Sponsoring Org:
- National Science Foundation
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