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On the Origin of Microplastics by Means of Natural Degradation

John Weinstein, The Citadel

16 March 2018

Plastic debris represents one of the most abundant and persistent contaminants in the marine environment. Despite their resistance to degradation, whole item plastics are vulnerable to eventual fragmentation in the environment. This is particularly relevant along beaches and in estuaries, where UV penetration into shallow waters and wave action make plastic brittle, thus increasing the likelihood of fragmentation. Since the 1960s, there have been numerous reports of microplastic fragments along the shorelines worldwide, and there is clear evidence that their abundance has increased in recent years. Since microplastic fragments occupy the same size fraction as plankton and particles of detritus, it is not surprising that recent laboratory studies have documented their ingestion by invertebrates with a wide variety of feeding strategies, including detritivores, deposit feeders, and filter feeders. Thus, microplastics have the potential to contribute to the decreased health and sustainability of estuarine species. This seminar will discuss on-going field studies characterizing the abundance of macro-and microplastic debris in Charleston Harbor, as well as their sources and fate in the estuarine environment. Results of recent field and laboratory studies demonstrating that microplastics are produced through the mechanism of surface delamination will be highlighted. The potential toxicological consequences of microplastic debris exposure on grass shrimp will also be discussed.