The concentration of microplastics compared to relative population proximity and basin residence times in Hood Canal and Whidbey Basin in Puget Sound, WA

Abstract

Microplastics enter waterways due to humans, however water circulation and winds can have an effect on where they concentrate. Microplastic concentrations are determined in Hood Canal and Whidbey Basin in Puget Sound, WA during December 2016. Eight stations were sampled using a 335 μm Manta Net towed from the R/V Barnes, then sieving water samples through a 0.33mm mesh sieve. Remaining products were then rid of organics, placed in a density separator, dried, and extracted for microplastics. By comparing microplastic concentration to basin residence times and population density, the main contributor to microplastic accumulation can be determined. Residence time (determined by wind and circulation) is a more important indicator to where plastics will distribute in Puget Sound. Microplastic concentration ranges from 0.069 pieces/m3 in Whidbey Basin to 0.36 pieces/m3 in southern Hood Canal. The mass of microplastics at each station was strongly attributed to the amount of Styrofoam present. This study acts as a baseline study for Puget Sound estuary and could help serve to understand where pollutant cleanups could be effective.