PS 75-133 - Occurrence of microplastic on national park beaches

Friday, August 11, 2017
Exhibit Hall, Oregon Convention Center
Stefanie L. Whitmire, Baruch Institute, Clemson University, Georgetown, SC, Tyler D. Pyatt, Biology, Clemson University and C. Anna Toline, Ocean Programs, National Park Service

Many studies in recent years indicate a strong presence of microplastic in the marine and coastal environment. Not only are they found floating in the ocean, they have also been found in organisms such as zooplankton, coral, oysters, and fish. Since plastic has the potential to adsorb contaminants, the risk to individual organisms and foodwebs could have large implications. Sand from 35 US Coastal National Park units was collected to investigate distribution of microplastic on beaches across the United States and its Territories. Collaborating with the National Park Service allowed us to sample beaches over a large geographic area, giving us a broad snapshot of the distribution of microplastic. Sand samples were collected from the Northeast, Midwest, West Coast, Alaska and Pacific Islands by NPS staff. Dried samples were sieved to remove large debris and and microplastic was separated from the sand using density separation. Factors that might contribute to the distribution pattern were examined, such as land cover, currents, distance to rivers and wastewater treatment.


Microplastics were found at all coastal sites with mean abundance ranging from 20 - 225 pieces per kg of sand. Variability was high both within and between sites. Fibers made up 97% of the microplastic pieces counted, with most of those being translucent or blue. Fibers originate from polyester and synthetic clothing such as fleece and are typically transported in wastewater. They also come from fishing line and rope that is not disposed of properly. Microbeads were only observed at 6 sites, with Alaska being the only region where microbeads were not found. No clear relationships to geographical features were apparent, including hectares of urban area within 50km of the sampling location, distance to the closest large river, and distance to wastewater treatment plants. High variability of microplastic loads and lack of strong geographic patterns were not completely unexpected given the broad geographic sampling scale and the numerous factors that could influence microplastic abundance along these shorelines.