20 - Mitigating Antibiotic Resistance in the Environment: Evaluating the Potential of Green Stormwater Infrastructure

Urban stormwater has recently received increased attention for its dissemination of emerging contaminants, specifically antibiotic resistance genes (ARGs). Stormwater acts as a carrier by transporting ARGs downstream, including into green stormwater infrastructure (GSI) systems, where ARGs can accumulate and potentially become long-term reservoirs for resistance. However, the capability of GSI to remove ARGs and their impact on ARG diversity in stormwater remain uncertain. This study aims to determine how GSI bioretention systems alter the concentration and diversity of ARGs in urban stormwater runoff. To do so, stormwater samples were collected at the influent of a storm drain diverting runoff from a highway overpass into a bioretention basin, the effluent of a rock swale transporting runoff from a highway overpass to a bioretention basin, and the underdrain of a bioretention basin representing the effluent of the entire system. The analysis of stormwater samples consists of three components: (1) qPCR to measure ARG removal rates through the bioretention system, (2) metagenomic sequencing to explore ARG diversity in stormwater and assess how GSI influences this diversity, and (3) combining the samples with surface water to monitor the impact of GSI effluent on ARG abundance and diversity in surface water. Results from this analysis will be presented, as well as a comparison of the concentration and diversity of ARGs in GSI effluent with those in a traditional storm drain outfall. From these outcomes we will determine the potential of full-scale GSI systems for reducing the risk of ARG dissemination in urban stormwater runoff.