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Community-Based Research Helps Shape PFAS Exposure Modeling Research

tyjahas on June 5, 2026

By Tyjaha Steele

A person sits behind a table with a University of Georgia Savannah River Ecology Laboratory tablecloth, displaying informational materials and forms on PFAS exposure and community-based research.

Tyjaha Steele staffs an outreach table at the Augusta-Richmond County Library, engaging with community members and recruiting potential participants for the study. (Photo courtesy of Tyjaha Steele)

PFAS, short for per- and polyfluoroalkyl substances, are a group of synthetic chemicals used in products designed to resist heat, grease, stains, and water.  Found in products ranging from nonstick cookware and cosmetics to water-repellent fabrics and firefighting foams, PFAS have become a growing focus of environmental and public health research because they break down very slowly and they can persist in the environment for years.  

Understanding how PFAS enters and impacts our daily life is not always straightforward. While drinking water is a well-known source of exposure, food and other everyday activities can also contribute. To better understand these pathways, researchers at the University of Georgia’s Savannah River Ecology Laboratory (SREL) worked with Richmond County, Georgia residents to develop a community-informed model that estimates PFAS exposure through food and drinking water. 

The recently published study combined environmental sampling, dietary information, hair sample analysis, and community participation to develop a probabilistic exposure model. Rather than relying on a single estimate, the model accounts for differences in household behaviors and helps researchers better understand how exposure pathways may vary among families. 

The study was led by Sizhuang Liu, a doctoral graduate research assistant, and Xiaoyu Xu, Ph.D., an associate research scientist at SREL, and includes contributions from Tyjaha Steele, science content strategist at SREL, and Katrina Ford, former director of outreach and education at SREL.  

Using a community-based participatory research (CBPR) approach, researchers worked directly with residents and trusted community organizations throughout Richmond County, Georgia. The approach encourages researchers, community members, and local organizations to work together throughout the study, ensuring community perspectives remain central to the research process.  

To connect with participants, the research team worked alongside organizations including the Augusta-Richmond County Public Library, First Presbyterian Church, Triumphant Family Christian Center, the Boys & Girls Club of Greater Augusta, and the HUB for Community Innovation Center. Additional support was provided by Appleby Library, The Earth Pantry, Dave & Buster’s of Augusta, Riverview Park Activities Center, and Dr. Charles Okpola of UGA Extension. Through these relationships, researchers were able to connect with residents through trusted community leaders and organizations, helping foster participation, build trust, and ensure the research remained rooted to community perspectives. 

Steele said one of the most memorable parts of the project was seeing the community’s interest in learning more about PFAS and environmental health. 

“Even people who didn’t qualify for the study still wanted to learn about PFAS, what it is, and how they could reduce exposure,” said Steele. “Their interest helped keep us focused on the ‘why’ of what we were doing, and a large part of that was bringing awareness to what PFAS are.” 

A translucent plastic bottle with a white cap stands behind two capped vials, each containing several brown insect specimens, on a dark surface—tools often used in exposure modeling or PFAS exposure studies.

Participants recorded and submitted food and tap water samples as part of the study to help researchers better understand potential PFAS exposure pathways. (Photo by Tyjaha Steele)

The study included 18 households representing 63 participants, and researchers collected both residential tap water samples, hair samples, and detailed dietary records documenting grocery purchases, takeout meals, beverage consumption, and commonly eaten foods. Water samples were analyzed for commonly observed PFAS compounds, including PFOA, PFOS, PFHxS, and PFHxA. Dietary records helped researchers better understand food consumption patterns and were combined using FDA food concentration data to estimate potential dietary exposure. Hair samples were used to provide insight into longer-term PFAS exposure patterns, helping researchers compare modeled exposure estimates with evidence of accumulated exposure over time. Using this data, researchers developed a probabilistic exposure model through Monte Carlo simulation, a statistical modeling approach that accounts for variability and uncertainty. 

“Exposure isn’t a single number, it’s a distribution,” said Liu. “By running 10,000 simulations per participant and resampling food intake and body weight over an entire year, we could estimate not just what an average day looks like, but also the full range of plausible daily exposures each person might experience.”

The resulting model highlighted the importance of considering multiple exposure pathways and demonstrated how different types of data can work together to provide a more complete picture of potential PFAS exposure. The community-based participatory research approach, combined with probabilistic modeling, also provides a framework that can be adaptable to other communities and refined as additional data become available. 

Community engagement remained a central part of the study long after samples were collected. Researchers returned household water testing results directly to participants through individualized reports that explained whether PFAS concentrations fell below or exceeded current EPA health advisory and screening thresholds. Families whose samples exceeded recommended guidance levels were encouraged to pursue follow-up testing, while all participants received information about PFAS exposure pathways, potential health concerns, and practical strategies that may help reduce future exposure. 

For Xu, maintaining those relationships with community members was an important part of the research process and reflects the principles behind community-based participatory research.  

“Community-based participatory research (CBPR) is an important way to understand how environmental hazards affect people’s health. In CBPR, researchers, community members, and local organizations work together as equal partners. Community members are involved throughout the process, including identifying local concerns, helping design the research, collecting and understanding information, and sharing results with others,” says Xu. “This collaborative approach helps ensure that the research reflects the real experiences and needs of the community. CBPR is especially valuable for identifying environmental problems that may affect some groups more than others. By better understanding why certain communities face higher exposure to contaminants, the findings can help guide policies and actions to reduce environmental unfairness and improve human health.”

The full study, Per- and polyfluoroalkyl substances (PFAS) exposure from dietary and drinking water by integrating probabilistic modeling and community-based research in a vulnerable community in the Central Savannah River Area, USA, was published in Human and Ecological Risk Assessment: An International Journal. Authors include Sizhuang Liu, Tyjaha Steele, Katrina Ford, and Xiaoyu Xu.

Out of Balance: What’s Limiting Freshwater Stream Growth 

tyjahas on May 4, 2026

What controls how much life a stream can support? For decades, scientists have pointed to nutrients like nitrogen and phosphorus as the main drivers of algal growth, which forms the foundation of aquatic food webs. This study takes a closer look at that assumption, asking whether other, less visible elements may also limit how these systems function. 

Researchers from the University of Georgia’s Savannah River Ecology Laboratory (SREL), in collaboration with researchers from multiple universities, examined how trace metals influence algal growth in freshwater streams. Trace metals are elements like iron and zinc that are needed in very small amounts but are still essential for life. The study was led by David M. Costello, a professor at Kent State University, and includes contributions from Krista A. Capps, an associate professor at SREL and with the Odum School of Ecology, Raven L. Bier, an assistant research scientist at SREL, and Dean E. Fletcher, a research professional at SREL. 

To test how trace metals influence algal growth in freshwater streams, researchers conducted experiments across 52 streams in the eastern United States, with 41 included in the final analysis, using small in-stream devices that slowly released nutrients and trace metals. By comparing how algal communities responded to different combinations of elements, the team evaluated whether growth depended on a single nutrient or on several working together. 

Growth limits were common across the study streams, and they extended beyond nitrogen and phosphorus alone. In more than 80% of streams, algae did not reach their full potential because at least one key element was in short supply. While nitrogen remained a major factor, trace metals were also frequently involved, showing that they are not just minor components but regular drivers of productivity. 

“The inspiration for this work came from an observation by Dave Costello, who led the study, that these trace metals are essential for core microbial and algal processes. They’re part of the enzymes that drive photosynthesis and nutrient cycling, so there was a strong reason to expect they might matter,” Capps shares. “But they’ve been largely overlooked because freshwater ecology has focused so heavily on nitrogen and phosphorus, and there’s been a long-standing assumption that metals in streams are abundant enough that they wouldn’t limit growth. What changed our thinking was seeing that biology line up with field evidence.”

Trace metals played a substantial role, and they often worked alongside more familiar nutrients. Iron influenced about half of the streams studied, while zinc played a role in roughly one-third, marking one of the first large-scale indications that zinc can limit growth in freshwater systems. Rather than acting alone, these metals were often part of a combination of elements that together controlled how much algae could grow. 

Adding a single nutrient often had little effect, but combining nutrients and metals led to much stronger responses. This reflects how biological systems function. Nitrogen and phosphorus help build new cells, while metals like iron and zinc support the internal processes that allow those cells to use energy and take up nutrients, so growth depends on having both the materials and the ability to use them. 

“To grow, organisms require many different elements, each at a different amount. When only one nutrient is provided, there is an imbalance as it alone cannot provide everything needed for living biomass. Rather, micronutrients such as metals are essential for building and operating those cellular structures in combination with macronutrients like nitrogen,” says Bier.

Algal responses also varied by group, and different types of algae showed distinct nutrient needs. Some groups increased when nitrogen and phosphorus were added, while others responded more strongly to metals like zinc. These differences help explain why changes in nutrient availability can shift not only how much algae grows, but also which groups become most common in a stream. 

Patterns across sites added another layer of insight, and streams with higher phosphorus levels were more likely to show signs of metal limitation. This suggests that as some nutrients increase, the demand for other elements can also rise and shape how ecosystems respond. 

“Concentrations of the macronutrients nitrogen and phosphorus have long been studied and measured throughout freshwater stream systems,” Fletcher says. “Identifying relationships between trace elements such Fe and Zn with these macronutrients is providing valuable insight to the likelihood of these trace elements limiting stream primary production.” 

Taken together, these findings point to a broader understanding of how streams function. Nitrogen and phosphorus remain important, but they are part of a larger network of elements that regulate biological activity, and overlooking trace metals may leave key processes unexplained. Recognizing how these elements interact helps clarify why streams respond differently to environmental change and may improve how freshwater systems are studied and managed. 

When Costello was asked about the future direction of this research, he responded: “This research has sparked many new questions. Many of the same trace metals that organisms need are also in high demand for batteries other advanced technologies, so understanding their natural availability is increasingly important” Costello shares. “We’re now taking a look at long-term water-quality records and encouraging agencies to included trace metals in routine monitoring. We’re also collaborating with ecotoxicologists, because these elements can become harmful at high concentrations, and we want a full picture of how they shape stream ecosystems.” 

The full study, Anaemic Streams: Iron and Essential Trace Metals Frequently Limit Primary Producer Biomass, was published in Ecology Letters. Authors include David M. Costello, Olufemi J. Akinnifesi, Renn C. Schipper, Paisley Kostick, Jordyn T. Stoll, Scott D. Tiegs, Amy M. Marcarelli, Sally A. Entrekin, Raven L. Bier, Krista A. Capps, and Dean E. Fletcher. 

Turning Trash Into Treasure: How scientists are using peanut shells and rice husks to clean up toxic mercury in our environment

on October 30, 2024

By Tyjaha Steele

Colored electron microscope image showing a magnified cross-section of a material—such as rice husks—with a scale bar indicating 250 micrometers and a chemical element legend, often used in mercury cleanup research.

An image of a sulfur-modified rick husk used in this study as seen under a scanning electron microscope. (Photo courtesy of Valentine Nzengung)

In the wake of Hurricane Helene and the recent flooding across the Southeast, it is crucial to understand the environmental impact of such events. Flooding historically causes sediment disruption which spreads harmful contaminants like mercury. These events can allow for toxic levels of mercury to enter the food web, posing serious risks to wildlife and humans. Researchers at the University of Georgia’s Savannah River Ecology Laboratory (SREL) have developed a promising solution to remediate this issue using biochar, a carbonized byproduct of organic waste. When added to contaminated soil, biochar can reduce the harmful effects of mercury, especially in flooded areas. 

Natural soil samples were collected for testing from the Phinizy Center for Water Sciences and Phinizy Swamp Nature Park in Augusta, Georgia. Mesocosms, enclosed environments designed to replicate natural ecosystem conditions, were used to simulate flooding conditions on a smaller scale. The soil sediment was then enriched with inorganic mercury, mercury that has been combined with other chemical elements, to mimic a pollution event before it was left to sit for 28 days.  

Different types of biochar, either rice husk or peanut hull, unmodified or modified with sulfur, were added to the soil, and the mesocosms were flooded to observe the effects of water on the polluted soil.  

“Peanut hull and rice husk were chosen due to their wide availability and established background research,” explains Xiaoyu Xu, an assistant research scientist at the University of Georgia’s Savannah River Ecology Laboratory and lead researcher for this study.  

The soil then sat to adjust again for 28 days. Afterward, the soil’s chemical properties were measured to see how they changed, and samples were collected to see how much total mercury, labile mercury, and organic mercury (toxic methylmercury) remained. Researchers then reviewed how each type of biochar, applied at different application rates, affected the amount of mercury that became more toxic over time.  

The measurements were repeated at 28-day intervals (56 and 84 days after biochar application) to monitor changes in its effectiveness over time and to determine the most efficient application method. Researchers discovered that sulfur-modified rice husks, applied between 56 and 84 days, worked best in stabilizing labile mercury in contaminated floodplains. Success was determined based on decreases in total mercury and labile mercury concentrations, and a reduction in methylmercury.  

“Overall, we found that adding biochar reduced the amount of mercury that can easily move and react in the environment by bonding with smaller particles, making the mercury more stable and less harmful,” states Xu. “However, adding large amounts of sulfur-modified biochar unexpectedly increased the production of toxic methylmercury.”  

The ability of biochar to stabilize mercury is especially critical as extreme weather events like Hurricane Helene highlight the risks associated with flooding. Heavy rainfall and floodwaters can redistribute harmful metals like mercury that are associated with health concerns in humans. The research findings suggest that using biochar could offer a sustainable and scalable solution for remediating contaminated sites. This method repurposes agricultural waste that would otherwise be discarded and reduces the mobility and toxicity of mercury. As a result, it lowers the risk of mercury entering the food chain and causing health issues. 

More research is needed to understand how sulfur-modified biochar affects methylmercury levels over time. “This approach shows promise as an environmentally friendly and cost-effective way to use organic byproducts to tackle mercury contamination,” Xu adds. 

The original article was published in the Journal of Environmental Quality by Brittany E. Jensen, Breanna Spencer, and Xiaoyu Xu.

A genetic clock can predict lifespan in mammals, UGA’s SREL research suggests 

on May 2, 2024

By Lauren Maynor

Two people wearing headlamps and outdoor clothing stand at night; one smiles while holding a small alligator with gloved hands, showcasing fieldwork for aging research linked to the University of Georgia’s quest to prevent aging.
University of Georgia’s Savannah River Ecology Laboratory former graduate student Emily Bertucci-Richter and SREL associate professor Benjamin Parrott in the field. (Picture courtesy of UGA SREL)

Do humans have a ticking clock within them that can determine their lifespan? The answer may surprise you.  

A recent study conducted by Emily Bertucci-Richter, a genomics analyst at the University of Michigan and former graduate student at the University of Georgia’s Savannah River Ecology Lab, and Benjamin Parrott, associate professor at SREL, has provided fascinating new insights into the phenomenon of epigenetic drift, also known as “epigenetic disorder.” This biological process is like a countdown within an animal’s DNA, marking the passage of time and influencing its rate of aging.  

“There are a lot of folks working on epigenetic aging as it relates to human health,” Parrott explains. “Age is a major risk factor for many human diseases including cancers, dementia, and Alzheimer’s.” 

Epigenetic drift is a process in which changes happen to an animal’s DNA as it ages, affecting the aging process. This research sought to unravel the mysteries surrounding epigenetic drift and its possible contribution to the differences in maximum lifespan observed across various mammal species. 

The researchers monitored how rats, mice, dogs, and baboons age and how chemical modifications to their DNA change over time. The study analyzed the dynamics of epigenetic drift accumulation with age across these four mammal species. They aimed to understand how it relates to maximum lifespan and whether CpG density, a specific DNA sequence, plays a role in buffering against epigenetic drift. Their findings hinted at the possible protective role of CpG density in mitigating the effects of age-associated epigenetic disorder.  

“Our working model and hypothesis are that CpG density does play a role in buffering against epigenetic drift,” Parrott says. “Other researchers have found that the CpG density in certain regions of the genome is higher in longer-lived species when compared to species with shorter lifespans. For example, humans, chimps, and dogs have greater CpG density than mice and rats.” 

The researchers found that all animals they studied experience epigenetic drift, but it happens faster in animals that have shorter lifespans. Their study suggests that there are other mechanisms, in addition to CpG density, that act to slow epigenetic drift. 

Parrott adds, “Genes involved in repairing DNA damage might underlie some of the differences in the rate of epigenetic drift. For example, Sirtuin proteins are involved in DNA repair and some nice work from Dr. Vera Gorbunova’s lab has shown that Sirtuins in longer-lived species are more efficient at repairing breaks in DNA when compared to the same genes in shorter-lived species.” 

These findings supported the researchers’ hypothesis that the rate of epigenetic drift explains maximum lifespan. The research conducted provided partial support for the hypothesis that CpG density buffers against epigenetic drift.  

Their research findings have significant implications in aging research. By understanding the role of epigenetic drift in aging, scientists may be able to develop new ways to predict and potentially slow down the aging process. 

“Our group is driven by basic curiosity,” Parrott says. “Why is it that some species live longer than others? What are the ecological and evolutionary dynamics that led to such wide variation in lifespans across the tree of life? These questions are a major inspiration for the work we do, and this study gets us just a bit closer to better understanding the answer.” 

The original study, The rate of epigenetic drift scales with maximum lifespan across mammals, was completed by Emily Bertucci-Richter and Benjamin Parrott at SREL.  

The Power of Progress: Head-starting and the Future of Mojave Desert Tortoise Conservation

on April 30, 2024

Researchers from the University of Georgia’s Savannah River Ecology Laboratory in collaboration with the University of California, Davis, recently conducted a study in the Mojave National Preserve in San Bernardino County, California, to further investigate the effectiveness of head-starting as a conservation tool for the Mojave desert tortoise. This species is currently listed as “Threatened” under the federal Endangered Species Act due to significant threats from habitat destruction and over-exploitation and was listed as “Endangered” by the State of California.

Kojima and Oswald awarded Fellowships

on August 13, 2021

Laura Kojima, a master’s student at SREL and the Odum School of Ecology, is the recipient of a 2021 National Science Foundation Graduate Research fellowship. The fellowship will provide a stipend for up to three years and additional funds to directly support her research.

“Receiving this fellowship is a huge honor, especially as an underrepresented minority in STEM. The process of grant writing and conducting my own research was a completely new process for me, and to have the mentorship and accessibility to successfully do so is something I am very grateful for,” said Kojima.

Kojima’s research assesses levels of chemical contaminants in alligator tail muscle and exposure concerns associated with the public harvest and consumption of alligators that travel on and off contaminated areas.

Scott Oswald, a doctoral student at SREL and the Warnell School of Forestry and Natural Resources, was recently named a recipient of the 2020 Office of Science Graduate Student Research fellowship from the U.S. Department of Energy.

The award is given for outstanding accomplishments in academics and research that show the potential to make important contributions to the mission of the DOE Office of Science. The fellowship will allow Oswald to conduct research at the Oak Ridge National Laboratory in 2022.

Oswald’s research will work to improve how large ecosystem models represent sugar and starch dynamics to better predict how plants respond to future climates, and to develop a framework for those dynamics using ecological and evolutionary theory.

“This fellowship is a good opportunity to receive mentorship and guidance about developing the ability to make connections between my background in mathematical biology and experimental observations,” said Oswald.

A woman with straight shoulder-length hair and a blue sweater smiles at the camera indoors, with blurred people and shelves—perhaps at a Kojima Fellowships event—in the background.

Ecological Society of America elects Beasley 2019 Fellow

on April 4, 2019

Jim BeasleyAiken, S.C. – James C Beasley, associate professor at the University of Georgia’s Savannah River Ecology Laboratory and the Warnell School of Forestry and Natural Resources, has been named an Ecological Society of America Early Career Fellow for 2019. He is one of eight recently selected for the honor.

According to ESA’s recent press release announcing the honor, Beasley was elected for outstanding contributions internationally in the field of applied ecology through his research in invasive species ecology, carnivore ecology, scavenging ecology and wildlife population ecology in landscapes abandoned following nuclear accidents.

ESA also states the honor is given to members who within eight years of completing doctoral training have advanced ecological knowledge and applications and show promise of continuing to make outstanding contribution to a wide range of fields served by ESA. Individuals are elected to serve for five years.

Beasley received a doctoral degree in wildlife ecology from Purdue University. Prior to coming to UGA, he was a visiting assistant professor at Purdue. In 2018, he was chosen as the UGA’s Fred C Davison Early Career Scholar.

ESA established its fellows program in 2012 with the goal of honoring its members and supporting their competitiveness and advancement to leadership positions in the Society, at their institutions and in broader society. Additional information about ESA Fellows and Early Career Fellows can be found on the ESA Fellows page.

SREL mourns Michael H. Smith

on November 20, 2017

The leadership and staff of SREL are deeply saddened by the death of Michael H. Smith, former and longest-serving director of SREL. Smith died on Nov. 15.

Big Mike, as he was affectionately known, earned an undergraduate degree from San Diego State University and a doctorate from the University of Florida. He served as director of SREL from 1973 to 1999, remaining as a professor of ecology at UGA until he retired in 2002.

Smith was recognized internationally as an expert in population genetics, ecology and radioactivity in the environment. His unique expertise evaluating the effects of radiation in the ecosystem led to his role as an adviser in response to the Chernobyl nuclear reactor accident.