Presence of microplastics in Salish Sea Nearshore sediments

Plastic pollution is a well-recognized issue afflicting water bodies worldwide. Recently, there is an increased focus on understanding the fate and distribution of microplastics, synthetic polymers less than 5 mm in diameter. These small plastics pose a potential danger to biota through ingestion and as a possible vector for contaminant transfer. Currently, we know little about the distribution of microplastics in sediments in the Salish Sea. Additionally, methods to efficiently and reproducibly quantify plastics in sediments need improvement. The US Geological Survey, in cooperation with the Washington State Department of Ecology and Washington State Department of Natural Resources, sampled 26 nearshore sediment locations in the fall of 2016 as part of the Regional Stormwater Monitoring Program. USGS analyzed microplastics in the samples, and results indicate the widespread presence of microplastics in marine sediments. Densities ranged from 2-65 pieces per 100 grams of sediment, and plastic fibers were 270% more abundant than other plastic material. Additionally, we found that small fibers, between 355 and 1000 µm, were 300% more abundant. This talk focuses on these results with consideration of how sediment drift relates to microplastic occurrence, steps taken to improve reproducible microplastic laboratory methods, and future directions for microplastic research in the Salish Sea.