UC unleashes new tools to track water pollution

University is leading global effort to understand how rivers influence drinking water

The University of Cincinnati is studying how pollution in a southwest Ohio river affects underground sources of drinking water for more than 2 million people in the area.

Assistant professor Reza Soltanian and his geology students in UC’s College of Arts and Sciences installed a suite of equipment at UC’s Theis Environmental Monitoring and Modeling Site, situated on the banks of the Great Miami River in western Hamilton County, that will provide the most comprehensive analysis of its kind about how rivers influence aquifers.

The cover of a sampling site.

UC researchers installed new sampling sites and sensors at the Theis Environmental Monitoring and Modeling Site.

The observatory was built in 2017 under the direction of geology professor emeritus David Nash in a patch of woods near soccer fields in Crosby Township. The project was a partnership of UC, Duke Energy, the Miami Conservancy District and the Great Parks of Hamilton County.

“The equipment is powerful for two reasons,” Soltanian said.

“First, the research. It has all these capabilities that will allow us to do a lot of real-time monitoring and modeling,” he said.

“But I also view it as a giant outdoor classroom. Students can come here and see all these different techniques used at research institutions and federal agencies around the world that study the interactions between rivers and groundwater. It gives UC a unique place to study hydrogeology.

“I think the observatory will definitely make our students more competitive in the job market,” Soltanian said.

The project demonstrates the commitment UC is making to research as described in its strategic direction called Next Lives Here.

Reza Soltanian holds a laptop while looking up at the observatory's equipment off camera.

UC geologist Reza Soltanian has developed one of the most sophisticated groundwater monitoring stations of its kind to track pollution and learn more about how rivers influence underground sources of drinking water. Photo/Michael Miller

The observatory provides real-time information about water flowing into and out of the ground beneath the Great Miami River. What they learn could help government regulators protect drinking water for more than 45 million Americans that rely on similar river-fed aquifers, Soltanian said.

“Our goal is to collect as much data as possible and to look at everything simultaneously to understand what’s going on,” Soltanian said.

Soltanian received support from a UC faculty startup grant, the National Science Foundation and a water technology cluster in Ohio, Indiana and Kentucky called Confluence.

Soltanian, NSF postdoctoral fellow Corey Wallace and master’s degree student Tyler McGarr spent the summer installing new sampling wells and an array of electrodes to capture the flow dynamics and geochemistry of the aquifer, particularly during floods when the entire sprawling site can be under six feet of water.

Previously, it would have been impossible to sample groundwater during a flood. You couldn’t exactly come out here in a canoe.

Corey Wallace, UC postdoctoral fellow

Data is recorded by instruments mounted atop a steel pylon that transmit information over a wireless signal even during the worst storms and deepest floods. UC researchers can track the changing river stages during or after storms. Sensors track changes in chemistry called redox, temperature, electrical resistivity, soil moisture and even the growth or loss of vegetation.

“Nobody’s ever done this three-dimensional spatial monitoring like what you see here,” Wallace said. “Previously, it would have been impossible to sample groundwater during a flood. You couldn’t exactly come out here in a canoe.

“This gives us a new way to observe what’s happening in real time and interpret how geochemistry changes before, during and after a flood,” he said.

UC’s observatory is part of a U.S. Department of Energy study network working to understand the dynamics of rivers, groundwater and watersheds.

“These new monitoring systems are the result of about two years of system design and testing, as well as our active collaboration with our industry partners and the DOE’s national laboratories,” Soltanian said.

Two people in face masks look at a laptop in the woods.

UC master's student Tyler McGarr, left, and UC postdoctoral fellow Corey Wallace check the real-time feed from the UC groundwater observatory's sensors. Photo/Michael Miller

UC began the project with a series of six monitoring wells at depths of 30 to 90 feet. Soltanian’s team has added eight new water-sampling sites for different depths. They installed an array of tiny electrodes that record the changing geochemistry of the aquifer and electrical resistivity of both the sediment and the water passing through it.

“There’s about 128 electrodes sunk to the ground that shock the subsurface to measure the resistivity of the sediments,” McGarr said.

This not only can tell researchers more about the gravel, sand, clay or bedrock under the ground but also can identify the role materials in the aquifer play in mixing river water and groundwater.

“You can work out what nutrients are being observed in the water at any time by combining our geochemical electrodes with water chemistry data,” Wallace said.

Wallace is trying to understand how groundwater flow influences contaminants such as nitrogen. His NSF-funded project uses data collected at the observatory to make computer models to explain and forecast changes in groundwater chemistry.

Video link: https://www.youtube.com/embed/pGWItYyj1ww?rel=0

The observatory also allows UC researchers to identify and track toxins in the water. There is particular concern for pollutants known as PFAS that are becoming more ubiquitous. Wallace said the observatory can detect whether contaminants get trapped in groundwater sediments in receding flood waters only to be released back into the river months or years later during subsequent floods. And the observatory will give them a better picture of how contaminants flow back and forth between rivers and groundwater.

“We’re excited about the project. It’s a real asset for understanding the groundwater resources that provide our drinking water,” said Mike Ekberg, manager of water resources monitoring and analysis for the Miami Conservancy District.

“There’s a lot we don’t understand about interactions in the water,” he said. “Our interest at the Miami Conservancy District is mainly in promoting good water stewardship. Scientific research has an important role to play to help us understand water resources and the threats to it.”

The steel pylon also features cameras that record foliage type and density. If plant growth goes into overdrive, UC can investigate whether excess nutrients in the groundwater such as nitrogen are to blame.

UC leases the property from the Great Parks of Hamilton County in a partnership similar to the one UC has at its Center for Field Studies next to Miami Whitewater Forest west of Cincinnati. UC conducts classes on everything from biology and botany to geology and anthropology at the sprawling and wooded field center.

UC biologist Kenneth Petren, director of the center, said it’s important to give students opportunities to put what they learn into practice.

“The groundwater observatory is an excellent example of how UC works with the local community to better understand our local environment,” Petren said. “The observatory is the beginning of what I hope will be several new projects related to water and the environment that will engage more students working with partners including the Environmental Protection Agency, our local parks and various organizations dedicated to environmental stewardship.”

Master’s student McGarr spent much of the summer at the observatory installing, configuring and refining the new equipment.

“All summer I was out here doing work and having an appreciation for things we read about,” he said. “I think it’s awesome that I get to do hands-on stuff instead of just learning about it in a classroom.” 

Featured image at top: UC student Tyler McGarr, left, UC assistant professor Reza Soltanian and postdoctoral fellow Corey Wallace check a live feed of data emanating from UC's Theis Environmental Monitoring and Modeling Site. Photo/Michael Miller

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