Progress Report – October 4, 2012

The Saint Louis “Ozone Garden”

An Education/Outreach Component of AQAST

Jack Fishman1,2and Kelley Belina2

Department of Earth & Atmospheric Sciences

Center for Environmental Sciences

Saint Louis University

St. Louis, MO

Preface

The St. Louis Ozone Garden Project is a collaborative effort led by Saint Louis University’s (SLU) Center for Environmental Sciences, in conjunction with the Saint Louis Science Center (SLSC) and the Missouri Botanical Garden. It is intended to be the prototype garden for NASA’s Air Quality Applications Science Team as an education and public outreach project that demonstrates the impact of air pollution on living systems.

End of the Summer Heat!

The heat wave and drought that affected St. Louis for much of this summer has gratefully passed. After the first week in September, temperatures recorded at the garden began to fall from the typical 90’s-100’s°F daily highs,and precipitation was recorded. As of this writing, the garden is well. The plants began to grow more rapidly with the cooler, but still summertime, weather in September. Currently, the leaves of the perennials, especially the milkweeds, are turning color as the plants begin to shut down during the fall.

Ozone Injury on Leaves in the Garden

In Mid-September we began to see the first signs this season of foliar ozone damage. This was firstobserved on the ozone sensitive variety of snap beans, and then on common milkweed. The appearance of these symptoms directly followed the break from our summer heat and drought and, it should be noted, appeared much later in the season than we had expected. It is exciting to finally see the effects of ground-level ozone pollution on many of the plants in our demonstration garden.

We attribute the fact that O3 injury was not present earlier, even with highO3 levels, to the unusually hot (even for St. Louis), dry weather. Daytime O3 levels recorded at the garden were consistently well above 40ppb, the threshold for leaf damage, throughout June, July, and August. During this time, average daily maximumswere generally between 70-80ppb with occasional (7 days) values over 100 ppb. A peak 15-minute value of 146 ppb was measured during the middle of the prolonged record-setting heat wave in late June and early July.

Ozone enters plants through microscopic pores on leaf surfaces called stomata. Open stomata allow CO2 to enter plants for photosynthesis,and other gasses such as O3 can enter the plant as well. Open stomata also allow water and O2 to escape the plant. In most plants stomata open during the day and closeat night for optimal photosynthesis during daylight hours. Many plants will also close their stomata to prevent high water loss in response to unfavorable environmental conditions such as hot temperatures (above 95°F), low humidity, and drought. While we did not have drought conditions in our garden due to an irrigation system, the plants likely closed their stomata for long periods of time this summer in response to the heat, direct sunlight, and dry air.

When the weather cooled in September, we observed more plant growth than previously, as well as the first signs of O3 damage on leaves, indicating that the stomata were likely now open during the day, and photosynthesis, along withthe ingestion of damaging concentrations of O3 was taking place. September daytime concentrations generally exceeded the 40-ppb threshold after the first week of the month when the remnants from Hurricane Isaac provided heavy rains to the region.

Other News

-We are happy to report data transmission problems between the O3 monitor and weather station in the garden, to the computer located in the SLSC Planetarium, where our data are captured and stored, have been solved. Much thanks to Bob Wurth of SLU’s Earth and Atmospheric Department for installing a wireless transmission system that now works perfectly. This is a system we will use in future gardens.

-We are beginning to trial an image software program as an additional method to quantifyfoliar ozone injury. In September we met with Susan Kelly, a curriculum developer from Connecticut, who has developed a protocol using software to score ozone damage on leaves. We plan to work with Susan tohelp her test her protocol for possible use in data collection, as well as its potential to be part of a plan to expand the ozone garden concept into science lessons that couldbe brought into schools.

-Kelley Belina, our garden Project Coordinator,traveled to North Carolina to visit the ozone garden at the Appalachian Highlands Science Learning Center in the Great Smoky Mountains National Park. Under the directionof Susan Sachs,a Park Ranger and the facility’s Education Coordinator, an ozone garden with plants native to the Smokey’s has been in operation therefor nearly a decade. Kelley was able to theobserve plantsat that site, which expressed considerably worse foliar injury symptoms, despite the generally lower concentrations in western North Carolina relative to those measured during this past summer in St. Louis. She was also able to observe and assist Ranger Sachs with educational programs, giving us ideas for ways to expand the educational component of the St. Louis Ozone Garden in the future.