Visualizing Ozone Pollution in the Denver Metro Area Using a Bioindicator Garden

Abstract

Since the industrial revolution, widespread fossil fuel combustion has significantly increased atmospheric pollution. The combustion of fossil fuels releases nitrogen oxides (NOx) and volatile organic compounds (VOCs), which form tropospheric (ground-level) ozone when exposed to sunlight. Ozone directly harms plants by disrupting their ability to absorb carbon dioxide, release oxygen, and carry out photosynthesis. Bioindicator species are plants that have visible responses to environmental conditions, such as ozone, and can act as “canaries in the coal mine,” indicating the health of their environment.  In this study, I use a garden of ozone bioindicator species (ozone garden) as a cost-effective tool for monitoring and visualizing the effects of anthropogenic ozone pollution.  My goal was to understand the damage tropospheric ozone has on plants in Denver using two varieties of beans: a common ozone-sensitive variety and a modified ozone-tolerant variety as a control. For a full growing season, I monitored the temperature, ozone concentration, and leaves for ozone damage. I found that the ozone-sensitive cultivar exhibited significantly more foliar injury compared to the tolerant cultivar (p<0.05) in response to tropospheric ozone. I also found evidence that ozone-sensitive snap beans experience a latency period in their response to foliar injury. All foliar injury data were added to a nationwide database of ozone gardens to contribute to understanding the relationship between ozone concentration and damage severity across different locations.