By Morgan Levey –
“You can ask the question, well do you expect this to look like the city or do you expect it to look like pristine prairie? And the answer is it’s going to be somewhere in between,” says Aaron Packman, professor in the Department of Civil and Environmental Engineering at Northwestern University and director of the Center for Water Research.
Packman’s question refers to levels of contaminants in the soil and water at Gensburg Markham Prairie, part of Indian Boundary Prairies, a remnant ecosystem just 20 miles southwest of Chicago. Over the past year the Institute of Sustainability and Energy at Northwestern University has been collecting data on the prairie site as part of an effort to study the benefits of urban green spaces for cities.
“People are designing green spaces, for example green roofs, but there is no data available about the benefits of these green spaces — for example soil water retention, or improvement of water quality, air quality,” says Liliana Hernandez Gonzalez a Ph.D student at Northwestern University and one of the project’s leads. “With high frequency data we can get models to understand them better.”
NU students in collaboration with ISEN presented the data they’ve collected over the past year at Gensburg Markham Prairie to members of The Nature Conservancy in an annual update for the partnership at Indian Boundary. The prairie site is owned by Northeastern Illinois University and The Nature Conservancy and managed by the conservancy. Gensburg Markham Prairie alone covers over 100 acres of well-preserved grassland, amid housing developments and highways.
The data covers everything from water levels and soil moisture to levels of outside contaminants and is difficult to assess. The ISEN team did find lead and zinc traces in the topsoil and copper traces in the water table. But the levels were less than 3 milligrams per meter, the EPA’s standard for levels of concern, and far below the average background levels for the state of Illinois.
“Those background levels are coming from the EPA, from a study they did in 1994,” says Gonzalez. “They took like 200 samples in the entire state and, near our site, they only took two samples. But that’s the data that’s available right now.” This outdated study is leading the team to look for other data sets from sites, preferably other prairies in the Midwest region.
To do that, the ISEN team installed 23 sensors in Gensburg Markham Prairie that measure soil moisture and water levels. Along with regularly sampling the soil and water, the team also installed a waggle node, technology developed by Argonne National Laboratory to collect real-time measurements of humidity, temperature, air quality and other environmental factors and transmit it via wireless internet to an open-source server.
So far the NU team has one of Argonne’s waggle nodes installed, as it’s dependent on power. “The next phase is to move them to the middle of the prairie, so then we need a solar powered waggle, which we’re working on now,” says Packman. “From there you could take them anywhere.”
An ISEN team presentation for the group at the prairie looked at potential areas of collaboration with The Nature Conservancy, particularly in areas of how the soil and water samples can inform the ecological restoration of the site.
“We, the NU team, don’t have expertise in conservation ecology,” says Packman.“Examples of new directions from the discussion with TNC include assessing the effects of urban inputs on degradation of prairie habitat in nature preserves like GMP, monitoring and controlling water levels for migratory bird habitat in restored wetlands, and use of the video cameras on the waggle nodes to obtain time-series data on plant communities.”
The effects that winter road salt has on the site is one of the areas of research that both organizations see as providing benefit for future management of the prairie.
“We dump massive amounts of salt into our waterways every winter. What do we see [from] that? There’s not enough research done,” says John Legge, Chicago Conservation Director for The Nature Conservancy. “It’s kind of mindblowing.”
In the last samples that ISEN analyzed, taken just two to three weeks before the presentation and three months after the last snow, higher concentrations of magnesium and calcium, key ingredients in road salt, were found in drainage ditches near the roads than in the middle of the prairie, according to Gonzalez.
“But they’re still lower than the background concentrations in Illinois,” says Gonzalez. “We took them in the summer. We’re planning to do more sampling in the winter and we’re also going to install some electrical conductivity sensors in water and soil and then we can get data all year, like high frequency data of these salt concentrations.”
All of the research at the prairie can be summarized as concern for the health of this rare remnant ecosystem’ and the need to gauge the human impact on the site.
“We think of this site as having huge value because of how pristine it is. Without having been plowed with having clearly some of the highest levels of plant and insect biodiversity in prairie remnants in Illinois. Just as a reference for what much of the state once was,” says Legge.
But it’s also essential for other sites that need ecological restoration.
“As others are working to recreate prairie habitat on areas that have had some other agricultural or other impacts, what are we aiming for?”
See related story: Prairie Plays Key Role in Chicago’s Flood Management