Microplastic Pathways in the Portland, OR Region: Results From Stormwater and Atmospheric Sampling

Document Type

Conference Paper

Publisher

American Chemical Society

Publication Date

8-16-2023

Keywords

microplastics, Oregon, freshwaters, microplasic pathways, stormwater, atmospheric sampling

Abstract

Microplastics are found ubiquitously in the environment, posing a potential risk to aquatic and marine life. However, the sources and pathways of microplastics to freshwaters require further characterization. In this work, two potential pathways of microplastics to freshwaters were quantified in the Portland, Oregon, USA region: urban stormwater and atmospheric deposition. Stormwater samples were taken from residential neighborhoods in Portland, OR during four storm events. A baseline concentration of 4.3 ± 2.0 (range 1.1–9.7) particles/L was found. Microplastic removal was then tested across three soil media types in bioretention columns. Removal across all soil media, including the Portland, OR standard soil mix was > 99%, indicating standard bioretention media can effectively reduce microplastic transport to freshwaters from stormwater. Atmospheric concentrations were estimated across a rural-urban gradient from Hood River to Portland Oregon using the moss O. lyellii as a bioindicator. Approximately 280 moss samples were taken from trees across gridded sections representing various land uses. Results provide insight into hotspots and potential spatial factors associated with the emission and deposition of microplastics. Findings can help develop a conceptual model of microplastic sources and pathways to freshwaters in the region.

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