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The St. Louis Ozone Garden

2012 Project Report

Kelley Belina1,2, Project Manager

Jack Fishman3,1,2, Principal Investigator

1Center for Environmental Sciences

2Center for Sustainability

3Department of Earth and Atmospheric Sciences

Saint Louis University

St. Louis, Missouri

January 2013

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Overview

The first St. Louis Ozone Garden was established in 2012 as a featured activity within Saint

Louis University’s (SLU) Center for Environmental Sciences (CES). This garden is an

education and public outreach project that demonstrates the impact of air pollution on plants

and the environment. It was open to the public in May 2012 near the entrance to the SLSC’s

McDonnell Planetarium in Forest Park. The project was a collaborative effort between SLU,

the Saint Louis Science Center (SLSC), and the Missouri Botanical Garden (MBG). This

report summarizes ozone pollution and its effects on plants, describes how the ozone garden

concept evolved, and highlights the milestones achieved during its first season. During this

first year of operation we encountered challenges and survived one of the hottest summers in

St. Louis history. In the end however the St. Louis Ozone Garden educated the public on the

detrimental effects of this pollutant on the environment, and provided an exciting dataset that

can be used for studying local air pollution.

Ozone Pollution and Damage to Plants

“Global Change” is a concept in the forefront of public awareness, but is often difficult for

the general public to visualize and understand. Although most people know that carbon

dioxide (CO2) concentrations have increased substantially (~25%), because of fossil fuel

combustion over the past century, ground level ozone (O3), which is also a byproduct of

combustion, has more than doubled over the same period of time. As a result, concentrations

of O3 in “clean” air now exceed levels at which damage to plants is observable.

Ground-level O3 is a secondary air pollutant formed primarily from vehicle exhaust and

power plant emissions on hot, sunny days and is the primary component of photochemical

smog. (This is not to be confused with “good” ozone in the stratosphere that shields the planet

from the sun’s harmful ultraviolet [uv] radiation). The oxidant properties of O3 make it toxic to

most living things. In humans, exposure to O3 over time causes health problems such as

respiratory irritation and infection, decreased lung capacity, and aggravated asthma.

Ozone enters plants through microscopic pores on leaves called stomata. Open stomata

allow gas exchange into and out of plants. While CO2 enters leaves for photosynthesis, any

other gasses in the air, including O3, also enter leaves through stomata. In addition, stomata

allow the plant to release water and O2 into the air. Once in a leaf, O3 weakens plants,

interfering with their ability to produce and store food, and making them more susceptible to

diseases and insect infestations. It also reduces a plant’s reproductive capability, which

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translates to yield decreases in many agricultural species. When O3 enters leaves in high

enough concentrations, plants respond with leaf cell death. Some plants are more sensitive to

O3 than others and exhibit specific and unique O3 induced symptoms. This allows visual

detection and quantification of O3 damage on leaves.

Scientific Perspective:

Increasing Ozone Concentrations are Now Harmful to the Biosphere

Tropospheric O3 has been the focus of the PI’s research for nearly 40 years. He was the

first to hypothesize that background levels of this oxidizing trace gas had increased

considerably since the onset of the Industrial Revolution in the late nineteenth century because

of the increase in fossil fuel usage (Fishman and Crutzen, 1978). This hypothesis was verified

through subsequent analyses of available datasets (e.g., see

Logan, 1985; Marenco et al., 1994). Furthermore, Kley and

Volz (1988) reexamined measurements from a French

observatory between 1876 and 1910 and concluded that

background concentrations had likely doubled, and possibly

even tripled since the late 1800s (see graph). More recent

analyses of background air show this increasing trend is

continuing through the first decade of the 21st century

(Parrish et al., 2009; Cooper et al., 2010). Similar to

projections that CO2 concentrations will increase through the

end of this century, background O3 concentrations are

projected to increase by an additional 25% (IPCC, 2007).

Unlike CO2, however, which is benign in the atmosphere, O3 is a toxic gas. High enough

concentrations of O3 will damage living organisms, including plants, trees, crops, and human

lung tissue. Laboratory studies have shown the threshold at which damage can take place in

plants is on the order of 40 pbb (parts per billion, or 1 molecule per 1 billion [109] air

molecules). Whereas Volz and Kley (1988) concluded that background concentrations in

central France were ~10 ppb in the late 1800’s-early 1900’s, current daytime concentrations in

the St. Louis area exceeds 50 ppb nearly every day in the summer. Since certain plants

express O3 damage at the current background concentrations, the Ozone Garden was

developed to show how O3 concentrations during the summer damage the biosphere, even

when air is considered “clean.”

Observed Increase in O3

measured in the background

atmosphere since late 1800’s

(after Parrish et al., 2009)

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Procuring Financial Support

Financial support for the first Ozone Garden in St. Louis was obtained through three

sources. The initial capital outlay for constructing the garden was primarily provided by a grant

from SLU’s President’s Research Fund, submitted by the PI and Dr. Allison Miller from the

Biology Department, entitled, “The Ozone Bio-indicator Garden: An Interdisciplinary Education

and Public Outreach Initiative to Demonstrate the Concept of Global Change.” Much of this

funding was passed through to the SLSC for the materials and personnel costs related to

buying and putting in the fence, providing the design and production of explanatory signage,

and installing an irrigation system; the other major cost covered by this grant was the purchase

of the ozone monitor and weather station. The second major source of funding was internal

funding from the CES, which was used to hire a dedicated project manager to oversee the

project; Kelley Belina was hired in February to serve in this capacity. The third source of

funding was from the existing NASA grant to SLU that supported the PI as a member of the Air

Quality Applications Science Team (AQAST). As part of his membership to this team, he

volunteered to be the Education/Public Outreach coordinator for AQAST; the intent of this

position is that several ozone gardens would be established around the country at the

institutions of other AQAST members (http://acmg.seas.harvard.edu/aqast/members.html).

The St. Louis Ozone Garden was envisioned to be the prototype garden for this network.

Putting the Garden Together

The idea for this project was brought to SLU by the PI, Jack Fishman, who had been an

atmospheric scientist at the NASA Langley Research Center in Hampton VA, before taking

over as CES Director in 2011. Prior to this, other ozone gardens had been planted in other

places, the longest running we know of at the Appalachian Highlands Learning Center in the

Great Smokey Mountains National Park. There are also plantings of ozone sensitive plants at

the Penn State Arboretum’s Air Quality Learning and Demonstration Center. More recently a

NASA publication, Ozone-Induced Foliar Injury Field Guide (Ladd et al., 2011; http://science-

edu.larc.nasa.gov/ozonegarden/pdf/Bio-guide-final-3_15_11.pdf), was written as a guide for

schools and educators interested in planting their own ozone-indicator gardens.

In St. Louis in 2011, Dr. Fishman contacted Dr. Cindy H. Encarnación, SLSC Director of

Life Sciences, and, through her partnership, the SLSC provided a public space and staff

support for the new garden. Dr. Fishman also contacted Sheila Voss, VP of Education at the

MBG, and Andrew Wyatt, VP of Horticulture, for greenhouse space, assistance starting plants,

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and advising on the project. The garden was planted in May 2012 in a highly trafficked

location near the entrance to the SLSC’s McDonnell Planetarium. The guidelines for the

garden were based on the design put forth in the above NASA Publication.

2012 Ozone Garden Preparations

Site and Display

Once a site for the garden was selected, we worked with Ron Staetter, SLSC Physical

Plant Engineer, and his staff to prepare for planting. The site, a

16’x16’ plot near the entrance to the McDonnell Planetarium in Forest

Park, was cleared and graded. A fence was installed and plans were

made to put in an irrigation system shortly after planting. The SLSC

also provided mulch, and CES brought in more after planting. CES

also applied topsoil from St. Louis Composting. The graphics team at

the SLSC worked with Dr. Encarnación and Dr. Fishman to design

educational panels describing O3 air pollution, its causes and effects,

and ways to work toward its reduction. The graphics team also

designed a lock box for public outdoor viewing and storage of the O3

monitor. A secure place inside the Planetarium was located for storing the data collection

laptop and weather station receiver.

Seeds and Plants

Seeds were obtained from two sources and started at the MBG greenhouses.

Pennsylvania State Emeritus Professor John Skelly provided seeds for the natural perennials

common milkweed (Asclepias syriaca), tall milkweed (Asclepias exaltata), and cutleaf

coneflower (Rudbeckia laciniata). These seeds were originally collected by Dr. Skelly in

Shenandoah National Park in Virginia from plants displaying O3 damage

symptoms. Seeds of O3 sensitive and tolerant varieties of snap beans

(Phaseolus vulgaris) were provided by Dr. Kent Burkey, USDA-ARS/North

Carolina State University. These seed came from his plant breeding and

research program.

With assistance from Horticulturalist Derek Lyle at the MBG, the

milkweed and coneflower seed was planted in early and mid-March, 2012.

Many plants were

grown from seeds at

the MBG.

The St. Louis Ozone Garden,

looking south-west toward the

entrance to the McDonnell

Planetarium.

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We tried germinating in a medium similar to native soil and in MBG’s recommended

germination mix, and received higher germination rates with MBG’s medium. Later in the

season we also added four swamp milkweed (Asclepias incarnate) plants to the garden, which

were grown from MBG seed collected at Gray’s Summit, MO.

Plants were transplanted and seeded into the outdoor plot in the spring. The garden was

officially open to the public on May 5th as part of “Family Day” activities at the Planetarium. On

that day three YES students transplanted the common and tall milkweed plants, and seeded

the two varieties of snap beans. Shade cloth was used over the transplants for 10 days to

protect them from direct sunlight as they adjusted to their new site. The cutleaf coneflower

was transplanted on May 16, with help from a SLU biology student. Also on this day, Channel

4 (KMOV) News filmed a segment of their “At the Center” program at the Ozone Garden. In

all, 12 each of common milkweed, tall milkweed, and cutleaf coneflower, and 18 each of both

snap bean varieties, were planted.

Ozone monitor and weather station

An O3 monitor and weather station were installed in the garden and May 21 was the first day of

data collection. This equipment was purchased through the GO3 Project

(http://go3project.com), a program based in Boulder,

CO that partners with schools around the world for

collecting O3 data and educating the public about

surface O3. As part of the GO3 Network the O3 and

weather data were continuously uploaded to the GO3

website in near-real time. The data from our site can

be compared to other GO3 locations across the

country and around the world. The weather station

and O3 monitor were located in the garden (the

monitor there for public display) and a laptop computer and weather station receiver were

located inside the Planetarium. After some issues with communication between the devices,

we developed, with help from Bob Wurth, an IT specialist at SLU, a secure wireless connection

between the outdoor and indoor components.

The O3 monitor sits in an enclosed secure box

in the garden (left photo). O3 and weather

data are transmitted to a receiver located

inside the planetarium connected to a laptop

computer (circle in right photo). From the

computer, the data are uploaded to the GO3

Project website (GO3Project.com).

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Growing the Garden: The 2012 Season

Spring and Summer

After the site was prepared and planted the 2012 growing and O3 seasons began. The

weather in St. Louis this year was the 4th warmest on record and the hottest since 1936. In

summary, there were 60 days of 90° or higher; 21 days of 100° or higher; and 11 days of 105°

or higher, a new record for this degree of heat.

Daytime O3 levels recorded at the garden were consistently well above 40 ppb, the

threshold for leaf damage, throughout June, July, and August. During this time, average daily

maximums were generally between 70-80 ppb 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 (see graph). 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.

Troubleshooting is expected in gardening, and from the start we encountered some

challenges to keeping the plants healthy. We worked in the early months to regulate the

irrigation system, and many days in early summer were overwatered. We also battled pill bugs

eating young snap bean seedlings. These pests were likely brought in on old compost and,

while an organic pesticide controlled their numbers, the pill bug populations continued to

resurge throughout the summer, due in part to wet soil. Another early season setback to the

OzoneDataObtainedduring2012:May21–November14(Dataplo edevery15minutes)

Harddrivereplaced

Newcommunica onsysteminstalled

May21 November14

The above panels provide a snapshot of the data collected during the time the instruments were operational. The data

were transmitted starting May 21 (left panel) and two major interruptions occurred when the hard drive in the laptop

had to be replaced in June and when a new communication system was installed in August. The panel on the right

shows the continuous O3 and temperature data record between June 28 and July 7, one of the hottest periods on

record in St. Louis. The red line marks temperatures of 100°F and the green line denotes O3 concentrations >40 ppb,

the threshold at which foliar ozone damage begins.

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snap beans was nitrogen deficient soil, which was rectified with more frequent fertilizer

applications.

For perennials, slow above ground growth is expected the first season as plants put energy

into establishing a root system. The extreme heat likely further added to slower growth in the

perennials than would have occurred in an average year. The tall milkweed plants grew poorly

in the beginning of the summer, and we later learned this type of milkweed does not grow well

in full sunlight. We replaced some of the tall milkweed with swamp milkweed, and also tried

planting O3 sensitive potatoes, which were unfortunately eaten as young plants by animal

pests. Animal critters found their way into the garden in late July and early August and ate

some of the plants. Patching a small opening in the fence solved this problem. Even with all

of these challenges, we are happy to report by the end of the summer the garden was growing

well and was an appealing educational display.

One unexpected outcome of 2012 was observing foliar O3 damage late in the growing

season. In the perennial plants we believe this was due primarily to the hot and dry conditions

causing the plants to keep their stomata closed throughout much of the day. Many plants

close their stomata to prevent high water loss under unfavorable environmental conditions

such as hot temperatures (above 95°F), low humidity, and drought. Thus, even with the high

O3 levels observed this summer, O3 was likely not entering the plant.

In September, after the heat wave broke, we began to see O3

damage symptoms on common milkweed plants. We did not see

symptoms in any of the other perennials. Dr. Skelly reported it is

often the case that O3 symptoms do not present in the first year of a

perennial planting. In the snap beans, O3 damage was also first

observed in September. In this case we believe the late appearance

of symptoms was due to the timing of the final snap bean planting.

The problem of pill bugs and other critters eating direct seeded snap

bean seedlings was solved by starting the plants in the greenhouse and transplanting them at

two weeks old. The snap beans transplanted in mid-August grew well and expressed O3

damage.

Foliar damage from ozone

finally appearing on

common milk-weed plants

in September.

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Fall 2012

As described above, in early September we began to see O3 damage on the common

milkweed and snap beans. It is likely that, even though O3 levels

were lower now than previously in the season, the stomata on the

milkweed were open and O3 was entering the plant. As well, this

time period corresponded to our late-transplanted snap beans. A

one-time count was taken of O3 damaged leaves on the sensitive

and resistant snap bean varieties and on average there were more

O3 damaged leaves, as well as

a higher percentage of

damaged leaves on the

sensitive than the tolerant plants (see chart). Snap bean

pods were also collected and are drying to be weighed.

Also notable in the fall was the first monarch caterpillar

sightings on milkweed plants. We will continue to

document monarch numbers.

The garden was closed at the end of October, when the

perennials were cut back and the snap beans removed. Next year with the perennials in their

second year of growth and possibly different weather conditions, it will be interesting to see if

and when O3 damage symptoms appear.

Students, Imaging Software, and Travel

We partnered with the SLSC’s Youth Exploring Science (YES) program, a science

enrichment program for historically disadvantaged high school students, to give interested

students experience working on this project. Of the three students selected this year, two

came to work regularly, and all were intelligent and cooperative. They learned about O3 air

pollution and its effects on plants, and gained experience working on a research project. The

lack of O3 damage during the summer months this year resulted in no conduction of visual O3

ratings, so there was less student work than had been expected. The students helped take

plant measurements, make plant and leaf labels, fertilize, prepare and plant when necessary,

and kill aphids on plants. They also checked on the garden during the weekends. We

appreciated working with these students and hope to continue to partner with the YES

program.

Late planted snap beans: O3 damaged vs. undamaged leaf count on Oct. 2, 2012

0

5

10

15

20

25

30

35

40

Total Leaves Damaged Leaves PercentDamaged Leaves

Average number of leaves per plant

Tolerant SB

Sensitive SB

- The O3 sensitive snap beans had more leaves than the O3 tolerant snap beans, and the leaves were observed to be smaller.- The sensitive snap beans had more O3 damaged leaves, and a higher percentage of damaged leaves than the tolerant snap beans (n=12 for sensitive and tolerant).

Differences between the O3-

tolerant snap beans (left) and the

sensitive snap beans (right) are

readily seen in these photos

taken in September.

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One aspect of the ozone garden concept that could be expanded in future years is the

creation of classroom-friendly lesson plans for schools interested in planting O3 sensitive

plants, and/or class visits to the gardens. Susan Kelly, a curriculum development specialist

based in Connecticut approached us with her idea to combine the ozone garden idea with

imaging software to create science and technology focused lesson plans for classrooms and/or

science camps. Project manager Kelley Belina trialed the ImageJ software protocol Ms. Kelly

developed for scoring O3 damage on leaves and found it to be a useful tool. Together with Ms.

Kelly we are looking for funding to support further efforts in this area.

In August Ms. Belina traveled to North Carolina to the Great Smokey Mountains National

Park to visit the Appalachian Highlands Learning Center and meet with Park Ranger Susan

Sachs. Ranger Sachs has overseen an ozone garden at this location for a number of years.

Data are collected by school groups visiting the Learning Center. These students, ranging in

age from elementary to high school, learn about O3 air pollution and other issues related to

environmental health. Plants in their garden are perennial species native to the Smokey

Mountains and are primarily common milkweed, cutleaf coneflower, and yellow crownbeard

(Verbesina occidentalis). Ms. Sachs has considerable experience with ozone sensitive native

plants and has worked with various researchers at other institutions. She continues to be an

excellent resource.

Ozone Garden Future

The first year of the St. Louis Ozone Garden was a success, with many thousands of

visitors viewing the garden and the collection of high quality dataset. We are currently

exploring options for expanding the ozone garden network. Our goal for 2013 is to continue

the Forest Park site, and start at least two more ozone gardens in the St. Louis metro area,

ideally one upwind and one downwind of the current garden. We would also, through Dr.

Fishman’s colleagues of AQAST, like to assist in establishing at least one ozone garden at a

national location. These would all be long-term sites.

To start more gardens we have been in discussions with potential partners for 2013 sites.

In the St. Louis metro area we have met with representatives from Southwestern Illinois

College (SWIC) and the Southern Illinois University Carbondale’s (SUIC) Agricultural Research

Station, both located in Belleville, IL. We also are pursing possible sites at Grants Farm and/or

Powder Valley Nature Center, both in St. Louis County. A site at MBG’s Shaw’s Nature

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Reserve in Gray’s Summit, south-west of St. Louis, is also a possibility. Possible national sites

include Houston TX, in conjunction with Rice University, and NASA’s Goddard Space Flight

Center in Maryland.

Plants in the gardens in 2013 will be similar to those in the 2012 garden with some small

changes. Possible changes, in the St. Louis area at least, include adding crownbeard plants

because their high sensitive to O3 makes them good demonstration plants. We also hope to

include O3 sensitive soybean plants and have been in contact with USDA-ARS/University of

Illinois researchers studying O3 sensitivity in soybeans to assist us in obtaining seeds. We

would also like to grow O3 sensitive potatoes (Solanum tuberosum), La Chipper variety. La

Chippers were planted in the Forest Park garden in 2012 but were eaten as seedlings.

To fund garden establishment and upkeep, we are currently exploring the interest of private

foundations for funding. Other NASA sources are also being explored, included Tiger-team

grant through AQAST, as well as part of an educational/outreach activity through TEMPO a

new-start satellite program focused on air quality.

Conclusion

We believe the St. Louis Ozone Garden’s first year was a success. The public was made

more aware of O3 pollution, its effects, and methods for its reduction; and about the increasing

background levels of O3 and its connection with environmental health, conservation, and

sustainable agricultural. We collected high quality O3 and meteorological data, and worked out

a reliable wireless data collection system. The YES students gained experience working in the

garden, and steps were made to think about expanding educational activities based on the

Ozone Garden concept. With this first year under our belts we gained knowledge and

experience we can use to expand the Ozone Garden Network in St. Louis and around the

country.

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References

Cooper O.R., et al. (2010) Increasing springtime ozone in the free troposphere over

western North America, Nature, 463: 344-348, doi:10.1038/nature08708

Fishman, J.; and Crutzen, P. J., The Origin of Ozone in the Troposphere. Nature, Vol, 274, No.

5674, pp. 855-858, 1978.

Ladd, I., J. Skelly, M. Pippin and J. Fishman, Ozone-Induced Foliar Injury Field Guide, NASA

Publication NP-2011-03-355-LaRC, NASA Langley Research Center, Hampton, VA, 135 pp.,

2011. (Electronic version available at: http://science-edu.larc.nasa.gov/ozonegarden/pdf/Bio-

guide-final-3_15_11.pdf)

Logan, J.A., Tropospheric ozone: Seasonal behavior, trends and anthropogenic influence, J.

Geophys. Res., 90, 10,463-10,482, 1985.

Marenco, A., H. Gouget, P. Nèdèlec, and J.-P. Pagès, Evidence of a long-term increase in

tropospheric ozone from Pic du Midi data series – Consequences: Positive radiative forcing. J.

Geophys. Res., 99, 16.617-16,632, 1994.

Parrish, D., et al., (2009), Increasing ozone in marine boundary layer inflow at the west coasts of

North America and Europe, Atmos. Chem. Phys. 9, 1303-1323

Volz, A., and D. Kley, Evaluation of Montsouris series of ozone measurements made in the

nineteenth century. Nature, 332, 240-242, 1988.