College of Science and Health Theses and Dissertations

Date of Award

Summer 8-24-2024

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Environmental Science

First Advisor

Mark Potosnak, PhD

Second Advisor

Liam Heneghan, PhD

Third Advisor

John Dean, PhD

Abstract

Air quality impacts are hard for the public to understand where air pollution is not visible. Visual indications of plant damage like stipples can help residents in cities with understanding how poor air quality impacts both plants and humans. This is particularly important since the effects of climate change and air pollution are difficult to observe at small temporal and spatial scales. Ozone gardens with ozone-sensitive plants are a space to visualize ozone damage on leaves of plants. They are a practical way to express these complicated scientific topics to the public, especially in heavily polluted areas like Chicago. Some plants are particularly susceptible to foliar leaf damage from ozone exposure known as stipples and that damage can be visually quantified, making them bioindicator species. Native plants that are bioindicators for ozone and snap beans with an increased sensitivity to ozone can be used as a tool for visualizing the damaging effects of ozone air pollution in ozone gardens. Three test sites were chosen to install ozone bioindicator gardens to test this phenomenon. Photosynthesis and conductance were measured at two sites while soil moisture was measured at all three sites to compare plant health throughout the experiment. Ozone concentrations and stipple counts were monitored in July and August of 2023. In ozone gardens installed in the Hilton Chicago O’Hare Airport, Peggy Notebaert Nature Museum (PNNM), and a residence in Highland Park, the hypothesis is that native and sensitive plant species will exhibit stipples while the resistant species will have significantly less to no stipples. Ozone concentrations and stipple percent coverage of leaves is expected to have a direct relationship. If the ozone garden is water stressed, the effect of ozone damage will be diminished, leading to both sensitive and resistant species having fewer stipples. Through generalized linear mixed models, Cutleaf coneflower (Rudbeckia laciniata) was found to have significant stipple coverage which supported its use as a native bioindicator for ozone detection. Common milkweed (Asclepias syriaca) and Wild lupine (Lupinus perennis) were found to not have significant stipple coverage under increased ozone, supporting their use as ozone damage resistant species. The R123 and S156 snap bean (Phaseolus vulgaris) variants were found to have significant stipple coverage and supports their use in ozone gardens. The R123 and S156 snap bean were found to be significantly different from each other through Tukey’s honestly significant difference test, supporting the use of R123 snap bean as a resistant species to S156 snap bean. Research is needed in more of the Chicagoland area and additional ozone gardens could help support the significance between ozone concentrations and stipple coverage.

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