The ultimate fate of materials in soils and sediments has relevance to both contaminant transport processes and global biogeochemical cycles. Consequently, we focus on the transformation of specific species in these subsurface environments. Chromium has become the second most common metal contaminant in the United States because of its utility in many industrial processes motivating us to study the stability of chromium containing solids. Furthermore, we are interested in unraveling an unclear process involving silica that occurs in marine sediments and may directly influence ocean pH.
Before returning to school to complete her B.S. in Chemistry at Georgia Tech (2010), Emily worked on various organic farms assisting in the development of sustainable farming practices and also at USU’s Water Research Lab collecting data for hydraulic and habitat simulations. Emily moved to New Zealand before entering into and completing an M.S. program in Chemistry at Northern Arizona University (2013). Emily is now working towards a PhD with Dr. Yuanzhi Tang and enjoys live music, tap dancing, and teaching step aerobics.
My research aims to understand the thermal evolution of pyroclastic flows during a volcanic eruption. Pyroclastic flows are composed of hot gas and rocks, and are fast moving currents that propagate due to the density differential between the flow and the ambient atmosphere. Due to the hazards and inability to see within a pyroclastic flow, we do not know how the temperature of the flow evolves or how particles are concentrated. Therefore, we do not fully understand the associated dynamics and hazards. I use multiphase numerical models that are constrained with field data and observations to study the internal physics and dynamics of the pyroclastic flows. I specifically work to examine the thermal evolution in order to constrain the concentration of particles and efficiency of the flows to entrain colder ambient air during the 2006 eruption of Tungurahua volcano, Ecuador.
Mary graduated summa cum laude from Mesa State College in Grand Junction, CO with a B.S. in Geology. She then did a one-year post-baccalaureate internship at Los Alamos National Laboratory. She is currently finishing up her Ph.D. in Dr. Dufek’s volcanology group and serves as the chair of the Graduates in EAS group. Mary received the Department of Energy Computational Science Graduate Fellowship and National Science Foundation Graduate Research Fellowship. In her spare time, Mary enjoys running, hiking, volunteering, and traveling.
My research focuses on the interactions between nitrogen and methane cycling in a northern latitude peatland in northern Minnesota, the site of the DOE Spruce and Peatland Responses Under Climatic and Environmental Change (SPRUCE) experiment. SPRUCE is a large-scale mesocosm project studying the effects of increased CO2 and temperatures on a nutrient-poor peatland ecosystem. Peatlands and permafrost regions have gained increased interest due to the predicted rise in temperature expected to impact these regions in the next century. The future of peatland’s role in the sequestration or release of carbon to the atmosphere is uncertain. For my Master’s research, I measured spatial and temporal variation in nitrogen fixation rates under varying temperature and methane concentrations for SPRUCE peat samples. My PhD research will investigate the response of microbial nitrogen and methane cycling to warming and elevated CO2.
Melissa I graduated cum laude from Kennesaw State University in Kennesaw, Georgia with a B.S. in Biology. She serves on the student committee for the 2015 Southeastern Biogeochemical Symposium and is currently completing her Master’s work in the group of Dr. Jennifer Glass and will begin her PhD in the summer. Dr. Joel Kostka and Dr. Chris Schadt (ORNL) are members on her Master’s committee. When Melissa is not working on her research, she can be found anywhere outside, running, hiking, horseback riding, and relaxing with friends and family.
The amount of volatiles and the dynamics of bubbles play a significant role on the transition between different volcanic eruption behaviors. The transport of exsolved volatiles through zoned magma chambers is complex and remains poorly constrained. Salah, in his PhD study, mainly focuses on the different transport of volatiles under two end member regimes: crystal-poor systems (bubbles form a suspension) versus crystal-rich reservoirs (multiphase porous media flow). To contrast the differences between the transports of exsolved volatiles in both regimes, the transport of a non-wetting phase in suspensions and porous media are characterized, separately, and then the effect of the transition zone on the over all flux is taken into account.
Investigating the dynamics of multi-particle systems to correctly integrate the effect of particle interactions on the rheological, mechanical and thermal properties of condensed matter is another aspect of his research interest.
Salah completed his B.S. in Mechanical Engineering at Urmia University (Iran) in 2009, his M.S. in Mechanical Engineering at Sharif University of Technology (Iran) in 2011, and recently completed another M.S. in Earth and Atmospheric Sciences at Georgia Tech.
The overarching goal of my research is to characterize and quantify the dynamics of subaqueous explosive volcano (aka Neptunian) eruptions. Neptunian eruptions are far less understood than their subaerial counterparts, yet equally hazardous. This discrepancy arises due to the near impossibility of collecting real-time eruption data. To gain insight into these systems, I am developing a multiphase fluid dynamics model, as well as a Neptunian Eruption Simulation Tank, to simulate (1) how fragmentation occurs (2) how material and heat are transported/deposited, and (3) how tsunamis are generated, during these eruptions. The overall goal is to use the model in concert with the experiments and field data to reproduce the 2012 eruption dynamics at Havre Volcano, New Zealand, the largest observed submarine eruptions in the last century.
Ryan graduated with Honors from the University of Texas at Austin with a B.S. in Geology. In 2012, Ryan received the Outstanding Student Paper Award at the American Geophysical Union meeting. He currently serves as chair of the Graduate Student EAS Seminar committee and organizer of the Geophysics Seminar. In Ryan's free time he enjoys brewing beer, watching/playing sports, and general adventuring.
I investigate the complex interactions between the solar wind and outer planet magnetic fields using sophisticated computer simulations. Planetary magnetospheres exhibit a wide variety of phenomena, thus functioning as natural laboratories in which we can investigate the behavior of magnetized plasma under different conditions. Understanding magnetospheric conditions is also vital to planning spacecraft missions, as high energy plasmas can pose a substantial radiation hazard. My thesis research focuses on understanding the global implications of the production and transport of new plasma in Saturn's magnetosphere. The presence of the Cassini spacecraft in orbit around Saturn provides us with valuable data with which to validate our results and develop our numerical tools.
Ashok completed his B.S. in Mechanical Engineering at Cornell University in 2006 and his M.S. in Mechanical Engineering at Georgia Tech in 2011.
My research interests revolve around developing sustainable solutions for environmental problems by utilizing the symbiosis between humans and nature. In the Taillefert lab I study how we can use uranium-breathing bacteria to clean up uranium-contaminated groundwater at nuclear facilities. Cost-effective remediation strategies that address nuclear waste spills are necessary to ensure that nuclear power is a safe alternative to fossil fuels. My dissertation investigates the duality of uranium as both a toxic contaminant and an energy source for bacteria and the geochemical conditions that control the fate of uranium in the subsurface.
Keaton completed his B.S. in Earth and Atmospheric Sciences at Georgia Tech in 2010 and recently received the Best Talk Award at the 2013 EAS Graduate Student Symposium. He currently serves on the steering committee for the Southeastern Biogeochemistry Symposium and is the founder and organizer of the Careers in Science seminar series. Outside of the lab, Keaton can be found throwing pottery, globetrotting, or rocking out to live music.
“My research focuses on discovering how tropical rainfall and atmospheric circulation patterns varied over the past two millennia. Since data from weather stations is only available for the last several decades, I use geologic archives like stalagmites to obtain information about Earth’s climate history. Stalagmites contain a record of past rainfall variability in the oxygen isotopic chemistry of their calcite layers. To better understand how oxygen isotopes reflect climate variability, I also conduct comparison studies between instrumental precipitation data and the oxygen isotopic chemistry of modern rainfall and cave dripwater. This research has taken me across the world to conduct fieldwork in places like Borneo and Papua New Guinea.”
Jessica graduated summa cum laude from the University of Tennessee at Chattanooga with B.S. degrees in Chemistry and Geology. She is currently a Ph.D. candidate in Dr. Cobb’s paleoclimate lab. She has received several prestigious awards, including the Barry M. Goldwater Scholarship, National Science Foundation Graduate Research Fellowship, Georgia Institute of Technology President’s Fellowship, and the P.E.O. Scholar Award.
Photo credit Jerry Wallace
Chastity Aiken is currently pursuing a PhD in Earth and Atmospheric Sciences at Georgia Tech. Her research with advisor Zhigang Peng focuses on studying deep tectonic tremor, a subtle fault movement in the lower crust, and its interactions with damaging earthquakes. Her work includes identifying tremor sources that are triggered by seismic waves of a large, distant earthquake along strike-slip faults where tremor has not been previously observed. In 2012, she installed seismometers in Costa Rica that recorded a magnitude 7.6 earthquake. Her research has covered much of the Western Hemisphere and has been published in international journals such as Nature Geoscience and Geophysical Research Letters. She has won a National Science Foundation Graduate Research Fellowship, as well as an ARCS Foundation Scholarship. In her spare time, she volunteers for Trees Atlanta, tutors high school students in physics and math, and engages in rock climbing.