Chemical identification of microplastics ingested by Red Phalaropes (Phalaropus fulicarius) using Fourier Transform Infrared spectroscopy

Chemical characterization of plastics ingested by wildlife helps identify sources of plastic pollution in nature and informs assessments of exposure risk to contaminants. In 2016, Red Phalaropes (Phalaropus fulicarius) were found dead on the north coast of British Columbia, Canada, during their southward migration. Previously, ingested particles suspected to be plastics were reported upon gut examination in all carcasses collected, which likely contributed to mortality. Here, we provide chemical identification of the ingested particles using Fourier Transform Infrared (FTIR) spectroscopy. Polymer identification was successful for 41 of the 52 analysed particles (79%): 41 (79%) were confirmed as plastics, 6 (11%) were not plastics, and 5 (10%) could not be identified. The most commonly ingested plastics were polyethylene (42%) and polypropylene (23%), both of which are known to float in the marine environment. Our study highlights the vulnerability of surface foraging seabirds to plastic pollution in the marine environment.