The following are two ESE MS Thesis Defenses taking place in April. Their defense announcements are attached.
Angelly Guarin
MS Thesis Defense
Lysimeter assessment of per- and Polyfluoroalkyl Substance leaching in a First-time Biosolids-Applied
Field Plot
Major Professor: Dr. Linda Lee
Wednesday April 15, 2026, at 9:00 AM | Lilly 2-425
Ecological Sciences and Engineering Interdisciplinary Graduate Program
Department of Agronomy
Abstract:
Per- and polyfluoroalkyl substances (PFAS) are persistent environmental contaminants found worldwide in water, soils, and living organisms. One pathway
for PFAS release into the environment is the land application of municipal biosolids, which are widely used to amend agricultural soils. This field-based study evaluates the early-stage vertical transport of PFAS following a first-time, single application
of biosolids to pastureland. Soil and pore water samples were collected over one year to track the transport and transformation of different PFAS compounds to depths of up to 1.2 m.
Results reveal contrasting behaviors among PFAS classes, with more mobile compounds exhibiting deeper transport through the soil profile. Over time, the
transformation of PFAS precursors increased the presence of mobile PFAS in pore water, highlighting potential risks to groundwater. Comparisons with a long-term biosolids-amended site further indicate that repeated biosolids applications can lead to greater
PFAS accumulation within agricultural systems.
These findings underscore the need to better evaluate biosolids management practices in the context of PFAS mobility and long-term environmental risk.
Ronnie Bernard
MS Thesis Defense
Drainage Water Recycling Impacts on Amphibian Populations in a Wetland Ecosystem
Major Professor: Dr. Laura Bowling
Thursday April 16, 2026, at 2:00 PM | Lilly 2-425
Ecological Sciences and Engineering Interdisciplinary Graduate Program
Department of Agronomy
Abstract:
Drainage water recycling (DWR) is used in agricultural landscapes to manage water resources, but its effects on wetland ecosystems and amphibian populations
are not well understood. This study focuses on a depressional wetland located at Purdue University’s Agronomy Center for Research and Education (ACRE) in central Indiana, where subsurface tile drainage from surrounding crop fields enters the system. Amphibian
activity, water quality, and wetland hydrology were monitored throughout the 2025 field season to evaluate how DWR influences habitat conditions. Amphibian surveys conducted from April through September documented species presence, calling activity, and capture
observations. Cope’s Gray Treefrog was the most frequently observed species, while Spring Peepers and Green Frogs showed more seasonal patterns. Following the installation of DWR, water levels remained elevated for longer periods, extending surface water presence
by approximately 8 to 12 weeks compared to pre-control conditions. This increase in hydroperiod improved the availability of aquatic habitat during key breeding and larval development periods. Water quality monitoring identified several commonly used agricultural
herbicides, including atrazine, metribuzin, metolachlor, and 2,4-D. Concentrations were highest early in the sampling period and declined over time, reflecting seasonal application and runoff patterns. Although some differences between sampling locations were
observed, they were not statistically significant. Results indicate that DWR can enhance wetland hydrology in ways that support amphibian habitat while also introducing agrochemical exposure. These findings highlight the importance of considering both ecological
benefits and potential risks when evaluating water management practices in agricultural systems.
Amy
Amy Ledman
She/Her/Hers
Lead Graduate Program Specialist Ecological Sciences and Engineering
Office of Interdisciplinary Graduate Programs
Ernest C. Young Hall, Rm 825
155 S. Grant St.
West Lafayette, IN 47907
o: 765-494-5865 f: 765-496-6271
Schedule a meeting:
calendly.com/aledman
