Concentration of Microplastics in Beach Sediments Surrounding Seattle, Washington in the Puget Sound Estuary

Abstract

Plastic pollution in the marine environment is an increasing concern. Microplastics (0.3-5 mm in size) are of most concern because they cannot be easily spotted, last the longest, and are easily ingested by marine organisms and make their way through the food chain. This study examines the distribution of microplastics found on Seattle beaches and on beaches to the north and south of the city. I collected sediment from three 1 m2 quadrats on each beach of my 12 sample sites using the Beach Sampling Protocol from the Port Townsend Marine Science Center to ensure comparison of data with other studies. The results show a total of 1,776 microplastic pieces/m2 collected at all twelve beaches, with a weak connection between spatial distribution and population density of nearby cities. As beaches erode, these microplastics are transported into Puget Sound and the Pacific Ocean. It remains an open question of how many and how much of these microplastic particles are exported from the beaches into the ocean.