POSTER PRESENTER: http://tinyurl.com/2024WSC-Michaels TITLE: Removing chloride ions and heavy metals from roadside bioswales on the Illinois Tollway with woody biochar ABSTRACT: Traffic, salt application, and pollution from construction along urban roadways contribute to elevated levels of chloride ions (Cl-) and heavy metals (cadmium, arsenic, chromium, & lead) in soils and waterways through runoff. Bioswales along the Illinois Tollway (IT) remove excess pollutants from stormflows and snowmelt, but they possess Cl- and heavy metal levels that surpass the Illinois Environmental Protection Agency's surface water quality standards. These systems are also invaded by Phragmites australis (common reed grass) and Typha × glauca (hybrid cattail). The removal of Cl- and heavy metals from these systems is imperative for the protection of downstream water quality, biodiversity, and ecosystem services. Harvesting invasive biomass reduces invasive regrowth, but it fails to address the nutrient inputs that drive invasion. Preliminary research suggests that applying biochar, a high-carbon soil amendment, post-harvest decreases plant-available nutrients by adsorbing nutrients and heavy metals to its surface. Four bioswales were selected for a fully factorial field experiment, each with 2 biochar treatment levels (no biochar, biochar present) and 2 harvest treatment levels (no harvest, harvest). We collected soil and plant tissue samples and surveyed vegetation metrics in fall and spring 2022 and 2023. Harvesting was completed in fall of both years with sickle bar harvesters and manual biomass removal. Ion chromatography and heavy metal analyses of the samples are being analyzed. This study predicts biochar addition will decrease Cl- and heavy metal levels in roadside bioswales with and without biomass harvest. This study may influence the use of biochar to mitigate pollution associated with highway systems. BIO: MacKenzie Michaels is a research assistant at Loyola University Chicago in Dr. Brian Ohsowski’s lab with a bachelor’s degree in environmental sciences from the University of Vermont. She studies restoration management practices in Great Lakes coastal wetlands. Her current research addresses the use of biochar as a restoration tool in sites degraded by hybrid cattail invasion and nutrient pollution.