Sascha Usenko B.S., Ph.D.
Professor of Environmental Science. Director, Environmental Science Graduate Program | Baylor University
Baylor, TX, UNITED STATES
Environmental chemist focused on transport, transformation & forensic fingerprinting of anthropogenic contaminants in aquatic ecosystems
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Biography
Dr. Sascha Usenko's, associate professor of environmental science, current research on whale earwax builds on his Ph.D. research, where he gained expertise reconstructing organic contaminant profiles in sediment cores. He obtained a bachelor's degree in environmental science and a doctorate degree in analytical chemistry from Oregon State University.
Using a wide range of analytical techniques such as pressurized liquid extraction and GC/MS, he reconstructed more than 280 contaminant profiles for 14 national parks throughout the western United States. Now using similar analytical techniques, his laboratory has developed the ability to reconstruct organic contaminant and mercury profiles for an individual whale using its laminated earwax plug.
As an analytical and environmental chemist, he was fascinated to learn that many whale species accumulate layers of wax in their ear canal forming an earplug over their entire lifespan, which is sealed from the external environment.
"I was elated to then learn that scientists in the past have used this waxy matrix as an aging tool, similarly to counting tree rings," Usenko said. "Then the question arose, could earwax plugs chronologically archive fat-soluble chemicals, such as man-made pollutants?"
Over the past two years, Usenko's laboratory has been working on developing the analytical methods capable of answering that very question.
"The answer is an emphatic yes! I am happy to report we now have the analytical methods capable of measuring organic contaminants, mercury, and now hormones in whale earwax," Usenko said. "Utilizing these methods, we can now reconstruct lifetime chemical profiles (i.e. from birth to death) for an individual whale for the first time."
Areas of Expertise (7)
Anthropogenic Contaminants
Spatial and Temporal Scales
The Transformation and Bioavailability of Persistent, Bioaccumulative, and Toxic Chemicals in the Environment
Environmental Forensic Chemistry
Identifying Unique Chemical Fingerprints
Contaminants
Aquatic Ecosystems,
Accomplishments (1)
National Science Fellowship Award
Awarded to Sarah Guberman for the Usenko Lab's work on pesticides.
Education (2)
Oregon State University,: Ph.D. 2007
Oregon State University,: B.S. 2001
Affiliations (7)
- Center for Reservoir and Aquatic Research Systems
- American Chemical Society
- Society of Environmental Toxicology and Chemistry
- Chemistry Steering Committed for SETAC
- Chemistry Advisor Group for SETAC
- University Sustainability Committee
- Phi Lambda Upsilon Honor Chemical Society
Links (1)
Media Appearances (4)
University of Houston Researchers Confirm Ozone & Particulates Are Issues In San Antonio Air
University of Houston online
2024-04-04
Baylor environmental science professors Rebecca Sheesley, Ph.D., and Sascha Usenko, Ph.D., collaborated with researchers from the University of Houston and Rice University to understand how the ozone and small particles are contributing to excessive air pollution levels in San Antonio.
Green Communities event in Waco brings climate risks, solutions into focus
Waco Tribune-Herald online
2022-09-14
Waco’s first-ever Green Communities Conference was held Wednesday at Baylor's Baylor Research and Innovation Collaborative (BRIC) facility. Baylor environmental scientist Sascha Usenko, Ph.D., was one of the 14 session presenters, highlighting the accelerating trends of both carbon dioxide levels and global temperature in the last 50 years.
Rebecca Sheesley and Sascha Usenko
Baylor Connections online
2021-07-23
AUDIO: How does urban pollution impact thunderstorm activity? It’s a question of interest to the Department of Energy, which turned to two Baylor professors to investigate. In this Baylor Connections, Rebecca Sheesley, Ph.D., and Sascha Usenko, Ph.D., professors of environmental science, discuss research that can uncover clues about thunderstorms in urban areas and lead to improvements in public health in Texas and beyond.
Baylor Researchers Earn Department of Energy Grant to Study Impact of Urban Pollution on Thunderstorm Activity
Baylor Media and Public Relations online
2021-01-07
Baylor University researchers Rebecca Sheesley, Ph.D., and Sascha Usenko, Ph.D., associate professors of environmental science, have been awarded an $890,000 grant by the Department of Energy Atmospheric System Research (ASR) to examine the impact of urban pollution on thunderstorm activity.
Research Focus (1)
Whale Earwax Research Exhibit
The whale earwax research is now in the Smithsonian Institution as an exhibit (see photo 4538). The Smithsonian National Museum of Natural History receives around 6 million visitors a year. The whale earwax exhibit is part of the Objects of Wonder.
Articles (5)
Temporal variation in groundwater quality in the Permian Basin of Texas, a region of increasing unconventional oil and gas development
Science of the Total Environment2016 The recent expansion of natural gas and oil extraction using unconventional oil and gas development (UD) practices such as horizontal drilling and hydraulic fracturing has raised questions about the potential for environmental impacts. Prior research has focused on evaluations of air and water quality in particular regions without explicitly considering temporal variation; thus, little is known about the potential effects of UD activity on the environment over longer periods of time. Here, we present an assessment of private well water quality in an area of increasing UD activity over a period of 13 months. We analyzed samples from 42 private water wells located in three contiguous counties on the Eastern Shelf of the Permian Basin in Texas. This area has experienced a rise in UD activity in the last few years, and we analyzed samples in four separate time points to assess variation in groundwater quality over time as UD activities increased. We monitored general water quality parameters as well as several compounds used in UD activities. We found that some constituents remained stable over time, but others experienced significant variation over the period of study. Notable findings include significant changes in total organic carbon and pH along with ephemeral detections of ethanol, bromide, and dichloromethane after the initial sampling phase. These data provide insight into the potentially transient nature of compounds associated with groundwater contamination in areas experiencing UD activity.
Spatial and Temporal Distribution of Current-Use Pesticides in Atmospheric Particulate Matter in Houston, Texas
Bulletin of Environmental Contamination and Toxicology2016 The atmospheric concentrations of seven current-use pesticides in particulate matter were determined at four locations throughout the Houston metropolitan area in TSP and PM2.5 samples from September 2013. Atmospheric concentrations in both TSP and PM2.5 ranged from below method detection limits (MDLs) to nearly 1100 pg m−3. The three compounds most frequently detected above MDLs were chlorothalonil, bifenthrin, and λ-cyhalothrin. Atmospheric chlorothalonil concentrations were above 800 pg m−3 in several TSP samples, but
Selective pressurized liquid extraction as a sample-preparation technique for persistent organic pollutants and contaminants of emerging concern
TrAC Trends in Analytical Chemistry2015 Sample preparation represents about two-thirds of the cost of analysis and often presents logistical bottlenecks in analytical and environmental chemistry laboratories, thus reducing our capacity and preparedness to quantify organic pollutants rapidly and accurately. Selective pressurized liquid extraction (SPLE) is an analytical technique that builds upon PLE by incorporating matrix-compound (i.e. interference) retainers into the extraction step, thereby reducing sample-preparation steps and increasing sample throughput. SPLE methods offer distinct advantages over traditional methods, namely reduction in the costs intrinsic to sample preparation (i.e. time, solvents, labor, laboratory space, training, and potential loss of analytes). The ability to analyze and to evaluate rapidly a large number of samples directly increases the analytical capacity and preparedness of a laboratory for certain situations (e.g. large-scale studies or environmental emergencies). We review the analytical improvements via SPLE and its wide-ranging applications.
Evolved resistance to PCB- and PAH-induced cardiac teratogenesis, and reduced CYP1A activity in Gulf killifish (Fundulus grandis) populations from the Houston Ship Channel, Texas
Aquatic Toxicology2014 The Houston Ship Channel (HSC), connecting Houston, Texas to Galveston Bay and ultimately the Gulf of Mexico, is heavily industrialized and includes several areas that have historically been identified as containing significant levels of mercury, dioxins, furans, polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs). Gulf killifish, Fundulus grandis, inhabit this entire estuarine system, including the most contaminated areas. F. grandis is the sister species of the well-established estuarine model organism Fundulus heteroclitus, for which heritable resistance to both PCB and PAH toxicity has been documented in several populations. F. grandis collected from two Superfund sites on the HSC and from a reference population were used to establish breeding colonies. F1 embryos from HSC populations were approximately 1000-fold more resistant to PCB126- and 2–5-fold more resistant to coal tar-induced cardiovascular teratogenesis, relative to embryos from the reference population. Reciprocal crosses between reference and contaminated populations exhibit an intermediate level of resistance, confirming that observed protection is genetic and biparentally inherited. Ethoxyresorufin-O-deethylase (EROD) data confirm a reduction in basal and induced cytochrome P4501A (CYP1A) activity in resistant populations of F. grandis. This result is consistent with responses previously described for resistant populations of F. heteroclitus, specifically a recalcitrant aryl hydrocarbon receptor (AHR) pathway. The decreased levels of cardiovascular teratogenesis, and decrease in CYP1A inducibility in response to PCB126 and a PAH mixture, suggest that HSC F. grandis populations have adapted to chronic contaminants exposures via a mechanism similar to that previously described for F. heteroclitus. To the best of our knowledge, this is the first documentation of evolved pollution resistance in F. grandis. Additionally, the mechanistic similarities between the population adaptation observed in this study and previous work in F. heteroclitus suggest that genetic variation predating the evolutionary divergence of these two species may best explain the apparent rapid parallel evolution of pollution resistance in genetically and geographically distinct species and populations.
Relative Importance of the Humic and Fulvic Fractions of Natural Organic Matter in the Aggregation and Deposition of Silver Nanoparticles
Environmental Science and Technology2013 As engineered nanoparticles (NPs) are increasingly used, their entry into the environment has become an important topic for water sustainability. Recent investigations point to the critical role of natural organic matter (NOM) in altering the persistence of NPs by complexing with their surfaces. The NP-NOM complex, in turn, is the new entity that may potentially influence subsequent fate of NPs. To understand the relative impact of humic (HA) and fulvic fraction of NOM on the stability and mobility of silver nanoparticles (AgNPs), a combination of dynamic light scattering and quartz crystal microgravimetry with dissipation monitoring was used. In the absence of unbound NOM, (1) surface modification on either AgNP or silica substrate by different NOM fractions could lead to substantial changes in the extent and kinetics of AgNP aggregation and deposition, and (2) HA has a greater capability to enhance the transport of AgNPs by reducing their aggregation and deposition. With unbound NOM, HA seems to compete more successfully for binding sites on the substrate under electrostatically favorable conditions and formed a steric layer to prevent subsequent deposition of AgNPs. These findings highlighted the importance of NOM fraction in the overall environmental partitioning of AgNPs.
