An NSF CAREER award, intended to help early-career scientists build a “foundation for a lifetime of leadership in integrating education and research,” is enabling Willenbring to make a connection between her use of the metal beryllium in reconstructing the history of the Earth’s landscape and the scourge of lead contamination in urban soils. With the common thread of soils and metal, she is hoping to advance scientific knowledge while bringing awareness to a public health threat.
Building on her postdoctoral work, Willenbring, an assistant professor in the School of Arts & Sciences’ Department of Earth and Environmental Science, will continue to explore the use of beryllium isotopes in dating soils. Beryllium, specifically the isotope beryllium-10, has been used widely by geologists like Willenbring to study how the earth’s surface evolves, as it gives an estimate of how long a given material has been exposed at the surface.
The beryllium found in Earth’s sediments comes from two sources: it can form inside minerals and it is formed in the atmosphere then falls to the ground in rain. Geologists have ways of measuring the beryllium-10 inside minerals, known as in situ beryllium-10, but the process is a laborious one. Measuring the beryllium-10 that originates in the atmosphere, known as a cosmogenic nuclide, which then adheres, or “adsorbs” to sediments, could potentially be a much easier way of quantifying landscape changes, but researchers are conflicted as to the method’s reliability.
“We’re trying to understand what controls the adsorption behavior of beryllium-10 so we can bring this new technique up to speed,” Willenbring said.
This alternative technique would open up new possibilities for geological study. Because in situ-produced beryllium-10 can only be studied in coarse-grained quartz, or essentially sand, it cannot be used in places where sand doesn’t exist, such as in the middle of oceans or lakes.
The CAREER Award will enable Willenbring to gain a greater understanding of how the association between beryllium and sediments forms and breaks. In the lab, she and her students will test beryllium adsorption and desorption on a variety of minerals under varying conditions, such as differing pH or organic matter content. After verifying the relationship of beryllium adhesion under different conditions, Willenbring’s team will test their findings using a field sample collected from the Amazon River basin that could reflect the major changes in landscape that have occurred in the region over the last 20 million years — namely, the rise and erosion of the Andes Mountains.
“In order to look back in time at how erosions rates have changed in response to the environment, like under climate change, you need to have a whole set of rates over time,” Willenbring said. “The only way to really do that is to examine this kind of beryllium-10 that adsorbs onto particles. If we get a good handle on this, it could open up a whole new range of possibilities.”
Each CAREER grant emphasizes not only pushing forward scientific frontiers, but educational ones as well. With her studies of beryllium in place, Willenbring saw a way of tying her study of soil metals to an issue with broad public interest: lead contamination.
In 2011, a group called Future Farmers held an event they called Soil Kitchen in conjunction with a conference on brownfields. There, they had community members bring in soil samples from their yards and tested them for metal contamination.
Willenbring liked the idea, and when she found out that Future Farmers had no plans to repeat it, she asked if she could take over the “Soil Kitchen” name and hold a similar event in Philadelphia. She’s done so every year since 2012. For this year's event, held in University City’s Dirt Factory on April 23, she received funding from Penn’s Year of Discovery and included assistance from Eco-Reps as a Sustainability Impact Project.
As part of the CAREER grant, not only is Willenbring organizing Soil Kitchen events in Philadelphia, but she is also unveiling a nationwide network of similar events to roll out in the coming years. Events are planned in Oakland, San Diego, New Orleans and Minneapolis-St. Paul.
At each, community members will have the opportunity to get anonymous results indicating whether their property contains problematic levels of heavy metals, such as arsenic, cadmium and lead. The samples are tested using a hand-held instrument called an XRF that uses X-rays to measure heavy metal concentrations; results are near-instantaneous. If levels come in high, Willenbring and her students can give the participants information on how to mitigate the effects of having contaminated soil.
Beyond the practical educational aspect of Soil Kitchens, Willenbring also sees them as an opportunity to build community and bring attention to the connection between healthy soils and human health.
“We see a lot of people coming who wouldn’t normally come together but who have a lot in common,” Willenbring said. “And we serve soup for free for everyone who brings in a soil sample. It plants the idea that soil is valuable.”
Last year Willenbring commissioned artist and PennDesign instructor Jacob Rivkin to create an animation tied to the theme of sustainability. He put together an animation, complete with an original harp score, which played during the Soil Kitchen event. This year he created another original piece, collaborating with Soil Kitchen participants, at the event.
Using results from the soil testing, Willenbring and her students will be using publicly available records of blood lead testing of Philadelphia’s children to identify any associations between soil lead and blood lead levels in the city. She will also be testing samples for beryllium to see if this metal — high levels of which can be toxic — is a problem in Philadelphia neighborhoods.
As another element of her CAREER Award efforts, Willenbring will also be training 6th grade earth science teachers in Philadelphia schools to engage students in lessons that relate community gardens, often planted at the schools themselves, to the science of food, plants, soil and sustainability.
“I like the the idea of a project-based approach that gets students thinking about things like how plants get their nutrients,” she said. “Then we could explore why some plants have high iron levels in them and why those might be the same plants that could have lead in them. They’ll start to see connections and how science is part of their everyday life.”