Poster 170 – Click on poster below to view presentation from author.
Washington State University
Co-Authors: Jenifer McIntyre, Jay Davis
Urbanization poses increasing threats to aquatic ecosystems including increased chemical loading. The impacts of urbanization on biological integrity are especially evident in the lowland, urban streams of western North America, where adult coho salmon (Oncorhynchus kisutch) returning to spawn in the fall have been prematurely dying at high rates. Previous studies have demonstrated the effectiveness of bioretention treatment systems in treating urban stormwater runoff, thereby reducing chemical loading into surface waters, and preventing acutely lethal and sublethal effects to aquatic organisms. The current study aims to determine the effectiveness and longevity of bioretention soil media (BSM) at various infiltration depths, including those shallower the depth currently required by the Washington Department of Ecology (18”). Experimental columns, containing five different BSM depths, were dosed with roadway runoff at an accelerated rate in order to simulate six water years in approximately 15 calendar months. The chemical and biological effectiveness of the columns in treating runoff was assessed using analytical chemistry and the health of juvenile coho salmon. Bioretention treatment efficiently removed copper, zinc, total PAHs, and total suspended solids (> 70% removal). Although all treatments continued to export nitrates after six accelerated years, the export of nutrients was greatly reduced by the end of the first accelerated year. Influent stormwater runoff was acutely lethal to juvenile coho salmon (88, 90, and 100% mortality in three exposures across the six accelerated years). However, treated effluent stormwater completely prevented coho morality for all bioretention depths and for all three exposures, indicating a continued ability to prevent acute lethal toxicity after six accelerated years of treatment. This study is ongoing and will continue to assess bioretention effectiveness through 10 accelerated years.
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All posts are publicly visible after review by site administrator. Students’ responses to posted questions is factored into scoring for the poster competition. Finalists announced May 25 and awards presented May 26, 2021.