Plastic Marine Debris Polymers in the Hawaiian Islands: Beach, Sea Surface, and Seafloor
Kayla C. Brignac, Melissa R. Jung, Cheryl King, Sarah-Jeanne Royer, Lauren Blickley, Megan Lamson, James Potemra, Jennifer M. Lynch
Identifying the polymer type of plastic marine debris is crucial for understanding sources, fate, transport, and effects of this emerging global contaminant in the environment. This is the first study to assess the polymeric differences of plastic marine debris in multiple environmental compartments across the Hawaiian Islands. Plastic marine debris was collected on 11 coastal beaches, 3 sea surface tows, 3 seafloor dives, and Midway Atoll to spatially depict polymer distribution in the North Pacific marine environment. A total of 4472 pieces were collected, in which a subset (n=3821) was analyzed for polymer identification using Fourier-Transform infrared spectroscopy (FTIR). The predominant polymers were high-density polyethylene (HDPE) (26.5%), polypropylene (PP) (26.3%), and nylon (22.8%) by mass, and low-density polyethylene (LDPE) (27.3%), PP (25.0%), and HDPE (16.8%) by pieces. Significant differences (p<0.05) in polymer composition were found among four compartments: sea surface, windward beaches, leeward beaches, and seafloor. Sea surface and windward beaches were dominated by floating, more weathered polymers, while sinking, less weathered polymers dominated leeward beaches and the seafloor. Our results are some of the first to provide evidence of polymeric stratification in the marine environment. The results emphasize that biota in different marine habitats are exposed to the impacts from different forms of plastic pollution.