Investigation of Microplastics from Deep-Sea Antarctic and West Coast North American Sediments

Microplastics have been found to be widespread and pervasive across marine ecosystems. There is growing body of literature to indicate that microplastics are globally distributed, including in deep sea sediments, yet there is a paucity of information from remote polar oceans, including deep sea sediments from the Southern Ocean. This information is useful, as any microplastic found from relatively remote or pristine locations may provide further insight into the distribution and accumulation of plastics in the marine environment. In this study, we examined microplastic densities and composition from deep-sea sediment samples collected from the Weddell Sea and west coast of North America. Samples from the west coast of North America were chosen due to closer proximity of populated coastlines, allowing a comparison to be made with the more remote Antarctic samples. Sediments were processed using density separation and vacuum filtration to extract and isolate microplastics and microfibers. Suspect particles were identified using microscopy techniques and then analyzed using µFTIR to determine polymer composition. Two polyester fibers and two polyethylene particles were identified in Antarctic sediments while only one polyester fiber was identified in the deep-sea sediments off the coast of North America. Although low levels of microplastics were extracted from the tested sediment cores, microplastics were observed in samples from Antarctica, often considered the most remote and pristine waters in the world. Surprisingly, low levels of microplastics were found off the more populated North American west coast samples. Further questions arise as to how microplastics are spread and sequestered in deep-sea sediments.