Bioretention of Stormwater: A Fungal Amendment Approach for the Remediation of 6PPD-Quinone
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Washington state is currently home to fourteen salmon and steelhead populations listed as threatened or endangered according to the Endangered Species Act (ESA). Salmon represent keystone species ecologically, culturally, and economically in the region. Urban runoff mortality syndrome (URMS) is a well-documented phenomenon which affects Coho salmon (Oncorhynchus kisutch) that come into contact with urban stormwater. A tire chemical transformation product was recently identified as the predominant toxin contributing to this phenomenon. The parent tire chemical, 6PPD, reacts with ozone to form 6PPD-quinone, which enters watersheds in roadway runoff. The median lethal concentration of 6PPD-quinone has been detected in both roadway runoff and receiving streams in urban watersheds of the Puget Sound. Bioretention is a proven method for reducing the toxicity of stormwater to Coho. Fungal amendments have been shown to improve the capacity of bioretention cells to treat stormwater, but current research leaves many questions unanswered.We aim to study the efficacy of using fungal inoculants in bioretention cells for reducing loadings of 6PPD-quinone into streams from stormwater. We will initially consider four species, Stropharia rugosoannulata, Pleurotus ostreatus, Pleurotus pulmonarius, and Trametes versicolor in a seed data collection experiment (SDCE). The SDCE will act as an initial trial, conducted in order to determine if the species of fungi can survive urbanized stormwater for a single treatment, verify the ability to detect and determine repeatable 6PPD-quinone concentrations in influent and effluent, determine local concentrations of 6PPD-quinone from various stormwater drainages, and narrow the candidate fungal species. This data will be used to inform the full-scale bioretention experiment in the following years.