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Long-term aging and degradation of microplastic particles: Comparing in situ oceanic and experimental weathering patterns

TitleLong-term aging and degradation of microplastic particles: Comparing in situ oceanic and experimental weathering patterns
Publication TypeJournal Article
Year of Publication2016
AuthorsBrandon J., Goldstein M., Ohman MD
JournalMarine Pollution Bulletin
Date Published2016/09
Type of ArticleArticle
ISBN Number0025-326X
Accession NumberWOS:000382339900043
Keywordsflour composites; ftir; gyre; low-density polyethylene; marine-environment; north; North Pacific Subtropical; Oceanic microplastic; organic pollutants; oxidation-products; Polyethylene (PE); polypropylene; Polypropylene (PP); refractive-index; spectroscopy; surface; Weathering

Polypropylene, low-density polyethylene, and high-density polyethylene pre-production plastic pellets were weathered for three years in three experimental treatments: dry/sunlight, seawater/sunlight, and seawater/darkness. Changes in chemical bond structures (hydroxyl, carbonyl groups and carbon-oxygen) with weathering were measured via Fourier Transform Infrared (FTIR) spectroscopy. These indices from experimentally weathered particles were compared to microplastic particles collected from oceanic surface waters in the California Current, the North Pacific Subtropical Gyre, and the transition region between the two, in order to estimate the exposure time of the oceanic plastics. Although chemical bonds exhibited some nonlinear changes with environmental exposure, they can potentially approximate the weathering time of some plastics, especially high-density polyethylene. The majority of the North Pacific Subtropical Gyre polyethylene particles we measured have inferred exposure times > 18 months, with some >30 months. Inferred particle weathering times are consistent with ocean circulation models suggesting a long residence time in the open ocean. (C) 2016 Elsevier Ltd. All rights reserved.

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