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Community-Based Research Helps Shape PFAS Exposure Modeling Research

tyjahas on June 5, 2026

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.

Nothing’s Set in Stone: What’s Taking Place Beneath the Surface

tyjahas on May 4, 2026

A person in a lab coat, gloves, and goggles handles samples inside a protective enclosure in a laboratory, revealing that beneath the surface of science, nothing’s set in stone. Vials and lab equipment are visible on the counter.

Peng Lin is shown working hands-on with cement in the lab (Photo courtesy of Peng Lin),

Although concrete is often seen as a stable barrier used to contain waste, it does not remain unchanged over time, and as it breaks down, it releases chemicals that can alter the surrounding groundwater. What happens when the materials designed to trap contaminants like uranium and strontium begin to change the conditions around them, and could those changes affect whether pollutants stay put or begin to move?

To answer this question, researchers from the University of Georgia’s Savannah River Ecology Laboratory (SREL), including Peng Lin, an assistant research scientist, and Daniel I. Kaplan, a senior research scientist, worked with collaborators from Savannah River Mission Completion (SRMC) and Closure & Disposal Determinations to examine how aging cement materials influence the movement of metals and radioactive elements in subsurface environments. Using sediments collected from the Savannah River Site (SRS) in Aiken, South Carolina, specifically from a subsurface low-level radioactive waste disposal area, the study explored how groundwater chemistry shifts as cement degrades and how those shifts affect contaminants such as uranium, cesium, and cobalt over time.

“People often assume these materials behave in a simple, predictable way underground, but that’s not the case. As cement-based materials age, they change the chemistry of the surrounding water, especially things like pH,” Lin shares. “These changes can strongly affect contaminants: some become tightly trapped, sometimes even forming solid minerals, while others can actually move more easily. Because of this, their behavior isn’t fixed over time and can vary depending on the type of contaminant and the surrounding soil.”

By recreating different stages of cement aging in laboratory experiments, the research team simulated how conditions change from newly formed cement to older, degraded material, and each stage reflected a different chemical environment. Newly formed cement creates highly alkaline conditions, meaning the water becomes more basic than natural groundwater, while older cement produces conditions that are closer to typical environmental levels. Using sediments collected several meters below ground, the team tested how contaminants, including uranium and strontium, responded across these different stages.

As these conditions changed, the behavior of contaminants shifted as well, and in many cases, they became less mobile under high pH conditions. Metals and radionuclides such as uranium, strontium, cesium, and cobalt were more likely to attach to sediment particles, a process known as sorption, which reduces their ability to move with groundwater. In some cases, these conditions also caused contaminants to form solid mineral phases, further limiting their movement. Compared to natural groundwater conditions, the results showed much stronger retention of several contaminants in the presence of cement-related leachates, in some cases increasing by orders of magnitude depending on the element and conditions.

“Many people might expect pollutants to simply dissolve and spread out, especially ones similar to common salts. But the results showed that some contaminants were actually trapped much more strongly in the presence of cement,” Lin states. “A particularly surprising finding was with cesium, a type of contaminant that behaves like familiar elements such as sodium or potassium and is usually expected to stay dissolved and mobile in water. Instead, the study found that cesium could become much more strongly retained in certain conditions, especially as the chemistry changed with cement aging.”

While this trend was consistent for many elements, responses varied depending on the type of contaminant, and not all showed the same level of change. Positively charged elements, such as uranium and cobalt, generally showed increased retention, while negatively charged contaminants, such as certain forms of technetium or iodine, responded differently and in some cases remained mobile. These differences are linked to chemical properties such as how easily an element dissolves in water or binds to particle surfaces, which means that each contaminant reacts differently even under similar environmental conditions.

As the cement continued to age, the strength of these effects shifted, and the ability of sediments to hold contaminants like cesium and strontium changed over time. Early-stage conditions, which are the most chemically extreme, often led to the strongest retention, while later stages produced more moderate effects as the chemistry moved closer to natural groundwater conditions. This progression highlights how contaminant behavior evolves alongside the materials meant to contain it.

Because sediment type also plays a role, the researchers observed that clay-rich soils tended to hold contaminants such as uranium and cesium more consistently, while sandy sediments showed greater variability depending on surrounding conditions. These differences influence how far contaminants might travel and how quickly they could move through the subsurface.

“When you look at all the findings together, they show that these underground systems are not static, which means they change a lot over time. As materials like cement age, they gradually alter the surrounding water chemistry, which in turn changes how contaminants behave,” Kaplan says. “What this helps us understand is that contaminants might not stay mobile forever, or stay trapped forever. Some may become more contained over time, while others could become easier to move depending on the conditions.”

By examining how cement materials, groundwater chemistry, and sediment type interact, the study provides insight into how contaminants behave in real-world disposal systems, and it helps improve predictions of long-term environmental risk. The findings also represent one of the more comprehensive efforts to quantify how cement aging influences the retention of metals and radionuclides like uranium, strontium, and cesium across a range of environmental conditions.

The full study, Age-dependent cementitious leachate effects on metal and radionuclide sorption to sediments from a subsurface waste-disposal site, was published in Applied Geochemistry. Authors include Peng Lin, Karah Greene, Wei Xing, Steven Simner, Christina Logan, Richard Henry, and Daniel I. Kaplan.

Looking Both Ways: The Role of Drivers in Animal-Vehicle Collisions

tyjahas on April 1, 2026

A dark, empty road stretches ahead at night, illuminated by vehicle headlights, with trees lining both sides and a single distant light visible—a reminder of the importance of road safety for every driver.

A dark and empty road stretches ahead at night, illuminated by vehicle headlights (Photo courtesy of Carson Pakula).

Roadways are often studied from the perspective of wildlife, where animals cross, when they move, and how they respond to traffic. These patterns have helped identify high-risk areas and inform strategies to reduce collisions. But every encounter on the road involves two participants. While animal behavior has been widely examined, the role of the driver, how hazards are detected, interpreted, and responded to in real time, has received far less attention, despite being a critical factor in whether a collision occurs.

Researchers from the University of Georgia’s Savannah River Ecology Laboratory examined this overlooked side of the interaction by focusing on how driver behavior influences animal-vehicle collisions. The study, led by Carson Pakula, who conducted the research as a doctoral student and is now a postdoctoral research associate, drew from 118 published studies to better understand how drivers notice, interpret, and respond to wildlife on roadways.

Rather than looking only at where collisions happen, the team focused on what drivers are actually doing in the moments leading up to them. They described collisions as a sequence in which a driver must first notice the animal, recognize it as a risk, and then react in time to avoid hitting it. When any step in that process breaks down, a collision can still occur, even when both the driver and the animal are behaving as expected.

“Most of the research so far has focused on animal-based behaviors with studies identifying the decisions animals must make to avoid a collision,” says Pakula. “As drivers are involved in most wildlife-vehicle collisions, I was interested in adapting this approach to identify what factors influences specific driver behaviors during an interaction. “

Across the research, vehicle speed emerged as one of the most consistent factors influencing collision risk. Faster speeds reduce the time available for drivers to react and increase the distance needed to stop, and these effects become even more pronounced at night. Headlights illuminate only a limited distance ahead, which means drivers may be traveling faster than they can safely see, especially on unfamiliar roads.

However, speed does not always affect collisions in the same way across different road types. High-speed roads may discourage animals from crossing, while moderate-speed roads can see more frequent crossings. These patterns reflect how closely driver behavior and animal behavior are linked, with each influencing the other.

The study also examined how warning systems, including standard roadside signs and animal detection technology, affect driver behavior. Traditional wildlife crossing signs often have limited impact because drivers become used to seeing them without encountering animals. In contrast, signs that activate when animals are present show more promise, as they can increase driver awareness and encourage slower speeds, although their long-term effectiveness remains uncertain.

Road conditions and surrounding environments also influence how well drivers can detect animals. Curves, dense roadside vegetation, and low-light conditions can reduce visibility, while open roads may encourage faster speeds or reduced attention. Animal characteristics further shape these interactions, as larger animals are generally easier to detect, whereas smaller or less visible species may go unnoticed until it is too late.

Despite decades of research, few studies directly measure how drivers respond to animals in real-world conditions. Much of what is currently understood comes from indirect evidence rather than observations of driver decision-making as it occurs.

“One of the biggest challenges with studying driver reactions in real time is the logistical difficulty of observing driver behavior in truly realistic conditions. While driving simulators and decoy animals allow for researchers to test how well drivers can detect animals, these approaches lack real world complexities which can which may limit how well the findings translate to actual wildlife encounters,” explains Pakula. “Capturing realistic driver reactions require natural, unanticipated encounters with wildlife, which is time and resource intensive. We still know relatively little about how driver behave during wildlife-vehicle encounters, particularly how different headlights impact how well drivers see animals and what evasive maneuvers drivers take during an encounter with an animal.”

These findings suggest that reducing animal-vehicle collisions will require a better understanding of both driver and animal behavior. While new technologies may help improve detection and response, their effectiveness will depend on how well they align with the way drivers perceive and react to risk.

Ultimately, reducing collisions will require more than a single solution, and progress will depend on combining insights from engineering, wildlife science, and human behavior. Each encounter on the road is shaped by both the driver and the animal, and understanding that interaction is the first step to improving safety.

The full study, Evaluating causes of animal-vehicle collisions through the lens of driver behavior, was published in Accident Analysis and Prevention and authored by Carson J. Pakula, Olin E. Rhodes Jr., and Travis L. DeVault.

Selenium Reduces Leucocytozoon Infection in Wild Birds: But at What Cost?

tyjahas on April 1, 2026

A person wearing gloves and a cap works with lab materials at a table in a wooded outdoor area, surrounded by scientific equipment and supplies, studying Selenium levels in wild birds.

Courtney Werner is seen banding and collecting blood samples from one of the birds captured throughout this study. (Photo courtesy of Travis DeVault)

Parasitic infections in wildlife species are influenced by more than just their exposure to parasites and their vectors in the wild. The environments animals live in, including the quality of their soil, water, and habitat, can affect whether infections occur and how they spread through populations. Chemical elements and contaminants present in the environment may subtly alter an animal’s condition, changing interactions among hosts, parasites, and the insects that transmit them.

In an attempt to better understand these relationships, researchers working at the University of Georgia’s Savannah River Ecology Laboratory (SREL) studied parasite infections in wild birds at the Savannah River Site (SRS) in Aiken, South Carolina, where relatively undisturbed habitats and areas affected by past industrial activity occur side by side. This study was led by former master’s student Courtney Werner, who was co-advised by Olin E. Rhodes Jr., Director of SREL and UGA Athletic Association Professor of Applied Ecology in the Odum School of Ecology, and Travis DeVault, Associate Director for Research and Senior Research Scientist at SREL. The team focused on haemosporidian parasites, a group of avian blood parasites related to the organism that causes malaria, and examined whether environmental contamination influenced rates of infection.

In natural systems, disease depends on more than exposure alone: birds serve as hosts, mosquitoes transfer infections between individuals, and parasites rely on both to complete their life cycle. Because contaminants can affect nutrition and immune defenses, the researchers examined whether exposure to contaminants was associated with differences in parasitic infection patterns, rather than only with direct harm to birds.

Over the course of one breeding season, the team captured 329 birds representing 31 species across six wetland and streamside habitats on the SRS, and collected blood samples to measure contaminant exposure and test for parasite infections. Mosquitoes, who are vectors of parasite transmission, were also sampled to determine whether differences in bird infections were driven by changes in the parasite infection rates of the mosquito vectors or by changes in immunity to the parasites within the birds themselves.

The study compared relatively uncontaminated areas with locations influenced by legacy industrial activities, including coal-combustion waste and nuclear-related contamination, and researchers measured several trace elements and a radionuclide in the birds. These included zinc, copper, mercury, lead, arsenic, and selenium, and cesium-137. Among the contaminants examined, selenium showed the clearest relationship with infection patterns.

“One of the clearest effects that we observed within birds was the relationship between selenium, a trace element commonly found in coal combustion waste, and a parasite that is commonly found in the blood of birds,” says Rhodes. “Birds with concentrations of selenium above a certain level, just did not have the parasite, despite the fact that many other birds in those same areas were infected.”

Birds living in areas affected by coal-combustion waste had higher selenium concentrations in their blood, and those elevated levels were associated with fewer infections from one parasite group known as Leucocytozoon. Individuals with selenium levels above a certain threshold showed no infection by that parasite, although the same pattern was not observed for other parasites, such as avian malaria (Plasmodium) or Haemoproteus, suggesting that contaminants influenced specific host–parasite relationships rather than all infections equally.

When researchers examined mosquitoes, however, infection rates did not differ between contaminated and reference sites. Instead, they followed seasonal patterns, increasing during the breeding season when dormant infections in birds can re-emerge and spread. These results indicated the contaminant was affecting the birds’ ability to resist infection rather than altering parasite transmission.

“These results suggest that some environmental contaminants, such as selenium, may influence individual host immunity more than they disrupt broad parasite transmission cycles within vector populations,” explains Daniel Peach, an assistant professor from SREL and the Department of Infectious Diseases in the College of Veterinary Medicine.

Although fewer infections might appear positive, selenium exposure can also affect reproduction, making the overall effect more complicated. Birds can transfer contaminants into their eggs, and higher selenium concentrations may reduce hatching success even while certain parasite infections in adult birds decline, creating a tradeoff between disease resistance and reproductive health.

The findings suggest that environmental contamination can reshape disease dynamics by influencing interactions among hosts, parasites, and vectors, showing that wildlife health is closely linked to ecosystem conditions. Understanding these relationships helps scientists better predict how species respond to human-altered environments and reveals that pollution may affect wildlife not only through toxicity, but also through changes in infection dynamics.

The full study, Use of Contaminated Habitat and Associated Selenium Uptake Mediate Haemosporidian Parasite Infections in Wild Passerine Birds, was published in Ecology and Evolution. Authors include Courtney S. Werner, Mary Chapman, Daniel A. H. Peach, Travis L. DeVault, and Olin E. Rhodes Jr.

Looking Closer: How Wild Pigs Choose Farrowing Sites

tyjahas on February 18, 2026

By Tyjaha Steele

A group of wild pigs’ piglets with striped and spotted coats huddle together on dried grass and leaves, surrounded by bare branches and plants at one of their farrowing sites.

Photo of a wild pig farrowing nest constructed of palmettos within a pine forest. (Photo courtesy of Jim Beasley)

For many animals, where offspring are born can influence their survival from the very first few moments of life. Shelter, nearby resources, and protection from disturbance all play a role in reproductive success. For invasive wild pigs, understanding where females choose to give birth, known as farrowing sites, can provide insight into their reproductive behavior and help inform more effective management strategies.

To better understand how wild pigs select these nesting locations, researchers from the University of Georgia’s Savannah River Ecology Laboratory (SREL) and the Warnell School of Forestry and Natural Resources examined farrowing site selection at the Savannah River Site (SRS) in South Carolina. The work began as part of former graduate student Sarah Chinn’s, Ph.D. research, during which she led the field component of the study, and was later expanded upon by Travis Stoakley, a current SREL graduate student, who led the analysis and writing. The study focused on 24 mature female wild pigs monitored using GPS collars and internal transmitters that signaled when birth occurred.

“Within the southern U.S. wild pigs give birth throughout the entire year, with many sows giving birth twice in a given year,” explains Beasley, a researcher and professor from the University of Georgia’s Savannah River Ecology Laboratory (SREL) and Warnell School of Forestry and Natural Resources. “This incredible reproductive capacity is one of the contributing factors to their ability to rapidly invade new areas and one of the biggest challenges to controlling their populations.”

A person wearing gloves and a cap examines a small animal in a forested area during daylight, possibly studying animal behavior near farrowing sites used by wild pigs.

Former doctoral student Sarah Chinn taking measurements on a piglet captured at a farrowing nest (Photo courtesy of Jim Beasley)

Wild pigs are among the most widespread and costly invasive mammals in the United States, causing billions of dollars in damage each year. Their high reproductive capacity allows populations to grow rapidly, making it difficult for land managers to slow or reverse their spread. While previous research has clarified when wild pigs reproduce, far less is known about the environmental features that influence where females choose to farrow.

Once researchers identified farrowing sites, they conducted detailed field surveys to document both fine-scale and broad-scale environmental characteristics. At each site, the team measured vegetation structure, light levels, temperature, canopy cover, and proximity to water. These features were then compared to nearby random locations to determine whether pigs were selecting specific conditions rather than using habitat at random.

The results suggest that female wild pigs consistently selected farrowing sites with dense and diverse understory vegetation and close access to water. All observed farrowing sites were located within a short distance of a water source, such as streams, ditches, or ephemeral pools. These areas may provide important thermal relief, hydration, and reduced travel demands during a time when females are less mobile and piglets are most vulnerable.

“Wild pigs are poor thermoregulators because they have few functional sweat glands, so they can’t easily cool themselves through evaporation and must rely on panting or behavioral modifications like seeking shade and water to cool down,” says Beasley. “Newborn piglets also have limited mobility their first few days, so having close access to water near the nest is likely important for both sow and piglet survival especially during hot summer months.”

A dense forest with tall trees and a large pile of green palm fronds scattered on the forest floor, possibly used as farrowing sites by wild pigs, illustrating fascinating animal behavior.

Photo of a wild pig farrowing nest constructed of palmettos within a pine forest. (Photo courtesy of Jim Beasley)

Researchers found that fine-scale understory vegetation was a stronger indicator of farrowing site selection than broader forest type. Farrowing sites consistently occurred in areas with dense ground-level cover, even when the surrounding forest classification varied. When the team examined broader land cover patterns using satellite-based data, distance to water emerged as the only strong predictor of farrowing site selection, while other landscape features such as forest type or proximity to roads were used roughly in proportion to their availability across the study area. This finding highlights an important challenge for wildlife managers: features that matter most to reproducing wild pigs often occur at a scale too fine to be detected using commonly available land cover datasets.

“Sole reliance on remote sensing data can often lead to missing the important fine-scale cues that help us understand wildlife behaviors. Satellite data that generalize the dominant vegetation type of an area wouldn’t capture the diverse plant communities or understory vegetation composition in forested areas that are captured by boots-on-the-ground field surveys,” states Stoakley. “So while ecology research and wildlife management increasingly rely upon remote sensing technologies to inform our inferences, there is no substitute for good old-fashioned ground truthing.”

This study suggests that wild pigs do not rely on a single habitat type when selecting farrowing sites. Instead, females appear to prioritize areas that provide nearby water and dense understory cover, regardless of the surrounding forest type. This could help explain the species’ ability to thrive in a wide range of environments, and complicates efforts to control their populations.

By identifying the environmental features associated with farrowing sites, the research offers practical insight for wildlife managers working to detect and disrupt reproduction during key periods. Knowing where wild pigs are most likely to give birth can help guide targeted monitoring and removal efforts, particularly in areas where eradication or population reduction is a priority.

The full study, Multi-scale predictors of farrowing site selection of wild pigs (Sus scrofa), was published in Applied Animal Behaviour Science. Authors include Travis E. Stoakley, Sarah M. Chinn, David A. Keiter, Linda S. Lee, and James C. Beasley.

How Hydroperiod and Tree Cover Influence Mercury Cycling in Carolina Bay Wetlands

tyjahas on February 18, 2026

By Tyjaha Steele

A wetland area with shallow water and tall grasses, featuring scattered young trees that contribute to the tree cover under a bright blue sky with white clouds.

Pictured above is a photograph of New Ellenton Bay (Photo courtesy of Amanda Hurst).

In wetlands, small changes in water levels and vegetation can have a significant impact on how elements move through the environment. Carolina bays are shallow, isolated, oval-shaped wetlands found throughout the southeastern United States that naturally fill and dry over time. Mercury, a naturally occurring element introduced through both natural processes and human activities, may remain stored in wetland sediments or be transformed into methylmercury, a form that more readily accumulates in plants and animals and moves through food webs. These pathways are shaped by local conditions, which vary widely among isolated wetlands in their water levels and vegetation structure.

To better understand how these factors influence mercury cycling, researchers from the University of Georgia’s Savannah River Ecology Laboratory (SREL) examined mercury dynamics in Carolina Bay wetlands at the Savannah River Site (SRS) in South Carolina. Led by Xiaoyu Xu, an associate research scientist at SREL, the study focused on ten Carolina Bay wetlands that differ in hydroperiod, the length of time water remains in a wetland each year. Some bays dry out seasonally (short-hydroperiod bays), while others remain flooded for extended periods (long-hydroperiod bays).

“In Carolina bay wetlands, mercury behavior is largely dictated by how long a wetland stays underwater, a cycle known as its hydroperiod. Short-hydroperiod wetlands, which are only seasonally flooded, typically act as mercury ‘sponges’ because their dense tree canopies capture mercury from the atmosphere and drop it into the soil via falling leaves,” explains Xu. “However, long-hydroperiod wetlands, those that stay flooded for most of the year, create the perfect environment for bacteria to transform inorganic mercury into methylmercury.”

Researchers collected surface sediment samples from each wetland during both wet and dry seasons and measured concentrations of total mercury and methylmercury. Sampling across seasons and wetland types allowed the research team to compare the amount of mercury accumulated in sediments and its rate of conversion into its more toxic form under changing environmental conditions.

A person wearing waders and sunglasses kneels by a stream in a forested area with dense tree cover, holding a plastic bag in their hands.

Cara Love, one of the co-authors listed on the paper, is seen collecting a sample at a wetland edge (Photo courtesy of David E. Scott).

The study suggests that wetlands with shorter hydroperiods, those that dry out part of the year, accumulated higher levels of total mercury, particularly when flooded. This pattern was associated with greater tree canopy cover, which can influence how mercury enters wetland sediments through natural processes such as leaf uptake and litterfall.

“The density of the tree canopy controls how much mercury enters the wetland in the first place and the leaves absorb mercury from the atmosphere and then deliver it directly to the ground,” says Xu. “The shade from a dense canopy protects the soil from sunlight, which would otherwise help ‘burn’ the mercury back into the atmosphere when the wetland dries out.”

Short-hydroperiod bays primarily functioned as storage sites for total mercury, whereas long-hydroperiod bays showed a greater capacity to convert mercury into methylmercury. The highest methylmercury concentrations were observed in the central areas of long-hydroperiod bays, where prolonged flooding supports conditions favorable to mercury methylation.

“Methylmercury is most concentrated in the deeper center areas of long-hydroperiod wetlands, which stay underwater for most of the year. These locations maintain waterlogged, oxygen-poor conditions where bacteria can convert inorganic mercury into methylmercury,” says Xu. “Identifying these hotspots allows us to better predict which species are most at risk and how methylmercury might move and magnify through the food web.”

The study suggests that mercury methylation potential decreased with increasing total mercury concentrations and tree canopy cover, with short-hydroperiod bays functioning primarily as sinks for atmospheric mercury and long-hydroperiod bays favoring methylmercury production.

The full study, Influence of hydroperiod and canopy cover on mercury accumulation and methylation in Carolina bay wetland sediments in the Southeastern United States, was published in Environmental Research. Authors include Chongyang Qin, David E. Scott, Stacey L. Lance, Demetrius Calloway, Cara N. Love, and Xiaoyu Xu.

SREL Director Dr. Olin “Gene” Rhodes Named 2025 Fred C. Davison Distinguished Scientist Award Recipient

tyjahas on November 18, 2025

November 18, 2025

Contact: Tyjaha Steele, (803) 508 – 0892

FOR IMMEDIATE RELEASE

Aiken, SC — The Savannah River Ecology Laboratory (SREL) is proud to announce that Dr. Olin E. “Gene” Rhodes has been selected as the recipient of the 2025 Fred C. Davison Distinguished Scientist Award. He will be formally honored and presented with the award during the 34th Annual Teller Lecture and Banquet in Aiken, South Carolina, on Nov. 21, 2025.

The award, presented annually by Citizens for Nuclear Technology Awareness, recognizes scientists and engineers whose lifetime scientific contributions have meaningfully shaped the scientific landscape. This year’s selection of Dr. Rhodes highlights his decades-long record of scientific excellence, transformative leadership, and service to the research community.

Since 2012, Dr. Rhodes has served as Director of SREL and, in 2021, assumed the additional directorship of the University of Georgia Research Institute. He also holds a faculty appointment at the Odum School of Ecology and serves as an Adjunct Professor at the Warnell School of Forestry and Natural Resources.

Dr. Rhodes completed his B.S. in Biology at Furman University in 1983, earned his M.S. in Wildlife Biology from Clemson University in 1986 and received his Ph.D. in Wildlife Science from Texas Tech University in 1991. His connection to the Savannah River Site (SRS) began early in his career when he conducted master’s research at SREL in the 1980s and returned in the 1990s as a postdoctoral researcher in theoretical population genetics.

Throughout his scientific career, Dr. Rhodes has authored or co-authored more than 250 publications covering wildlife ecology and genetics, the application of molecular tools in conservation, species reintroduction strategies, wildlife diseases and human-wildlife conflict. Throughout his career, he has also maintained a consistent role in mentoring graduate students and postdoctoral researchers.

Under Dr. Rhodes’ leadership, SREL has expanded its research publications, modernized facilities using external funding, broadened outreach and education efforts and grown graduate, faculty, and staff populations. These accomplishments complement his professional recognition as a Fellow of the American Association for the Advancement of Science (AAAS), a Fellow of The Wildlife Society, and a member of the Sigma Xi Scientific Research Honor Society.

This record of scientific achievement and leadership aligns closely with the legacy of Dr. Fred C. Davison, for whom the award is named. Davison’s career was defined by his commitment to encouraging math and science education and doubling graduate enrollment, principles that have guided Dr. Rhodes throughout his tenure at SREL and in his contributions to the broader scientific community.

The Savannah River Ecology Laboratory, a research unit of the University of Georgia located near Aiken, South Carolina, studies a wide range of ecological research topics, including contaminant transport and ecotoxicology, wildlife ecology, conservation genetics, and ecosystem restoration. For further information, call SREL at 803-508-0892 or e-mail connect-srel@uga.edu.

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SREL Conducts the Annual Graduate Student Symposium for 2025

tyjahas on September 10, 2025

Students from the Graduate Student Symposium of 2025 pose together for a group photo outside. (Photo courtesy of Tyjaha Steele)

Anna Bushong and Skylar Nichols are pictured smiling with their award keychains. (Photo courtesy of Tyjaha Steele)

The 2025 SREL Graduate Research Symposium was hosted on September 4th at the Savannah River Ecology Laboratory, where graduate students shared innovative work across conservation, ecology, ecotoxicology, plant ecology, and wildlife biology. The day featured a keynote address by Dr. Nick Haddad on biodiversity and habitat fragmentation, followed by sessions on wildlife ecology, ecotoxicology, ecosystem disturbance, and remediation. Talks ranged from wildlife responses to headlights and avian strike risk at airports to mosquito ecology in wild pig wallows, epigenetic aging across species, PFAS release from soils, and much more.

The symposium concluded with awards recognizing outstanding student presentations, including Skylar Nichols for Best 5-Minute Talk on mosquito–flower interactions, Anna Bushong for Best 15-Minute Talk on developmental abnormalities in the imperiled gopher frog, and Sydney Burgy for Best Poster Presentation on PFAS exposure in largemouth bass.

With a packed schedule of presentations, posters, and discussions, the symposium highlighted the depth of graduate student research at SREL and celebrated their contributions to the future of ecological science.

Holding On or Letting Go: How Freshwater Species Manage Radiocesium Exposure

tyjahas on July 15, 2025

By Tyjaha Steele

Katie Quinlin is seen releasing mosquitofish into R-Canal enclosure to start the uptake experiment. (Photo courtesy of Katie Quinlin)

As legacy nuclear sites shift toward long-term stewardship, understanding how contaminants behave in the environment is critical for informed cleanup and monitoring decisions. Radiocesium (¹³⁷Cs), a byproduct of nuclear fission, remains a concern due to its persistence and mobility through food webs. New research from the University of Georgia’s Savannah River Ecology Laboratory (SREL) and the Warnell School of Forestry and Natural Resources enhances our understanding of how freshwater aquatic species absorb and eliminate this contaminant, supporting future risk assessment and remediation strategies. 

Led by former SREL and Warnell graduate student Kathryn Quinlin, the study was conducted at R-Canal, a waterway historically affected by reactor operations at the Savannah River Site (SRS). Researchers focused on four freshwater species: bullfrog tadpoles, red swamp crayfish, eastern mosquitofish, and American white-water lilies.

“These species were selected for their availability and because they represent distinct ecological roles such as primary producers, benthic omnivores, and pelagic carnivores,” says Quinlin. “Together, they provide a broader picture of how radiocesium moves through freshwater systems.”

To monitor contaminant uptake, researchers enclosed each species in mesh cages within the contaminated canal. After exposure, they transferred the organisms to a clean reference pond to observe elimination rates.

Bullfrog tadpoles absorbed radiocesium the fastest, reaching equilibrium in under nine days. Crayfish followed at just over 50 days, and mosquitofish took around 86 days to reach steady levels. Despite the slower uptake, mosquitofish and tadpoles reached similar radiocesium activity concentrations, both higher than those found in crayfish.

“These findings challenge the idea that sediment-dwellers always accumulate more contamination,” states Xiaoyu Xu, an associate research scientist at SREL and co-author on this study. “Tadpoles likely absorb more radiocesium due to their vascularized skin and higher metabolic rates, while crayfish have hardened exoskeletons and a slower metabolism, which may limit uptake.”

Once in the clean pond, tadpoles shed half their burden in under eight days, and water lilies cleared ¹³⁷Cs at a similar rate (around 12 days). Crayfish eliminated the contaminant more slowly, with a half-life of 69 days, while mosquitofish took about 43 days.

Xu notes that, “Slower elimination in crayfish and mosquitofish is likely tied to traits like lower metabolism and less permeable surfaces. Tadpoles, kept in warm indoor tanks, were more active, whereas crayfish were outdoors in cooler weather and unable to molt, a pathway hypothesized to be important for shedding contaminants.”

Differences in radiocesium storage pools also affect how long species retain radiocesium and influence its persistence in aquatic systems. Tadpoles and water lilies likely store more radiocesium in short-term reservoirs, resulting in rapid cycling, which contrasts with the longer-term reservoirs where crayfish and mosquitofish are thought to be storing this contaminant.

Radiocesium’s persistence, even at very low concentrations, can quietly influence aquatic communities over time. By capturing these subtle effects, the research contributes to a deeper understanding of radioactive contaminants and their long-term consequences for ecosystem function.

“This study offers a direct comparison of radiocesium uptake and elimination for a variety of species under natural conditions. By documenting how species absorb and eliminate contaminants over time, the findings inform selection of bioindicator species, improve environmental modeling, and help guide monitoring and remediation at contaminated freshwater sites,” explains Beasley, a professor at SREL and co-author on this study. “This research also adds to the growing body of evidence that radiocesium cycling within aquatic food webs is complex and influenced by a myriad of biotic and abiotic attributes of ecological systems.”

The full study, Uptake and elimination of ¹³⁷Cs in aquatic biota inhabiting a contaminated effluent canal, was published in the Journal of Environmental Radioactivity. Authors include Kathryn A. Quinlin, Danielle Hill, Xiaoyu Xu, and James C. Beasley.

Headlights and Hesitation: How Vehicle Lighting Affects Deer Behavior in Imminent Collision Scenarios

tyjahas on June 25, 2025

By Tyjaha Steele

Carson is pictured with a fawn at UGA’s captive deer facility in Athens, Georgia. (Photo courtesy of Carson Pakula)

There’s a reason the phrase “deer caught in headlights” is so well-known. It captures a split-second moment with very real consequences, often at the expense of the driver and the animal themselves. With thousands of injuries and billions of dollars in damages reported each year, researchers are now asking whether changes to vehicle headlights could significantly alter how deer respond, potentially reducing the risk of collisions.

Carson Pakula, a doctoral graduate research assistant and lead author of the study, conducted 174 trials at the Whitehall Deer Research Facility in Athens, Georgia, through his work with the University of Georgia’s Savannah River Ecology Laboratory and Warnell School of Forestry and Natural Resources. The team worked with 23 captive, wild-type female deer, testing eight lighting combinations using an oncoming electric golf cart outfitted with halogen or LED headlights (set to high or low beam), with or without a rear-facing lightbar.

“We chose these eight treatments to explore how vehicle lighting might affect deer behavior by testing different headlight types, since halogen and LED give off different colors of light,” explains Pakula. “We also compared low and high beams to see if brightness changes how deer react, and added a rear-facing lightbar to find out if lighting up the front of the vehicle makes it easier for deer to notice.”

The study focused on short-range encounters, which ranged just 95 meters between the deer and the vehicle, designed to simulate the final seconds before a potential collision. Using infrared cameras, researchers tracked alert behavior, when a deer stopped or reoriented in response to the vehicle, and flight behavior, when it made an apparent attempt to escape.

Carson is seen setting up an infrared camera on a field vehicle. (Photo courtesy of Carson Pakula)

Across all trials, deer alerted in 73% of cases and fled in just 52%. Halogen headlights on high beam with the lightbar off produced the most alerts, yet no lighting treatment reliably triggered flight behaviors.

“Many deer showed no flight behavior and stayed in the vehicle’s path, regardless of lighting treatment. It’s a ‘freezing in the headlights’ response familiar to many drivers,” says DeVault. “Deer reactions seemed driven more by individual personality than lighting. Their dark-adapted vision may not align well with modern headlights.”

Carson smiles alongside the golf cart used to test how variations in vehicle lighting impacted deer responses to an approaching vehicle. (Photo courtesy of Carson Pakula)

This is the first study to test how vehicle lighting affects the behavior of a moving deer during an imminent head-on collision. Previous research has focused on roadside deer or longer-range interactions. These findings establish a baseline for future studies that may explore lighting effects in free-ranging deer or longer-distance approaches, especially as 86% of new vehicles are built with LED systems by default.

Although LED headlights emit blue wavelengths that correspond to what deer’s eyes are most sensitive to, halogen high beams still prompted the strongest alert responses. It’s unclear whether LED lights overwhelm the deer’s vision, mask movement cues, or simply fail to appear threatening under certain conditions.

While lighting may influence how deer perceive an oncoming vehicle, it doesn’t appear to change the outcome of a close encounter. Broader mitigation efforts, such as fencing, road design, or population control, remain more consistent and scalable solutions for reducing deer-vehicle collisions.

The full study, Caught in headlights: Captive white-tailed deer responses to variations in vehicle lighting during imminent collision scenarios, was published in Applied Animal Behaviour Science and was authored by Carson J. Pakula, Gino J. D’Angelo, Adrianna Mowrer, Olin E. Rhodes Jr., and Travis L. DeVault.

Category: News

By Tyjaha Steele

By Tyjaha Steele

By Tyjaha Steele

By Tyjaha Steele