Colloquium Schedule

Department Members, University of Maryland - College Park

September 4, 2026 at 11:00 am (ESJ 1215)

At this, the first colloquium of the 2026-2027 Academic Year, members of the newly named Department of Geological, Environmental, and Planetary Sciences (GEPS) will get to know each other, their wide range of expertises, and their research interests through a series of fun activities.

Hongfei Liu and Oya Kawashima, University of Maryland - College Park

September 18, 2026 at 11:00 am (ESJ 1215)

Hongfei Liu: Mineral association state tracks microbial enrichment in mineral-associated organic carbon

Mineral association is a major mechanism underlying soil organic carbon (SOC) persistence, yet mineral-associated organic carbon (MAOC) is often assumed to be preferentially derived from microbial residues. However, whether microbial-derived and non-microbial carbon follows the similar accumulation behavior in MAOC, and whether the microbial enrichment in MAOC relative to bulk SOC varies with mineral association state, remains unresolved. Using horizon-resolved soils from 43 U.S. National Ecological Observatory Network sites, we combined size–density fractionation, hydrofluoric-acid extraction, amino-sugar biomarkers, C K-edge XANES, solid-state 13C NMR, FT-ICR-MS, and radiocarbon analyses to link MAOC composition and solubility with source partitioning across mineral-association gradients. Soluble MAOC followed a Langmuir-type accumulation pattern and was enriched in phenolic- and carboxyl-rich, lignin-, tannin-, and condensed-aromatic-like compounds, indicating stronger plant-associated signatures. In contrast, insoluble MAOC accumulated without an apparent asymptote and was enriched in alkyl-rich, non-aromatic compounds with stronger microbial-associated signatures. The two fractions showed no significant difference in radiocarbon values. At the continental scale, microbial-derived carbon shifted from enrichment to depletion in MAOC relative to bulk SOC as MAOC/SOC increased, with a reversal near 48%, whereas non-microbial carbon showed the opposite pattern. Depth and chemical weathering were more strongly associated with non-microbial than microbial-partitioning, while humid and arid profiles showed contrasting depth trajectories. Together, these findings show that microbial- and non-microbial carbon differ in accumulation behavior because of their distinct solubility and chemistry, while their relative enrichment in MAOC varies systematically with mineral-association state rather than uniformly favoring microbial residues.

 

Oya Kawashima: Development of Mass Spectrometers for Space Exploration: From Lunar Volatile Analysis to Organics

Mass spectrometry is an important technique for in-situ chemical analysis in space exploration, enabling the identification and quantification of volatiles, organics, and isotopic signatures on planetary surfaces. Specifically, I am working on the instrumentation of space-flight mass spectrometers across three projects. The first is TRITON, a time-of-flight mass spectrometer developed for LUPEX (Lunar Polar Exploration; a joint JAXA-ISRO mission scheduled to launch in 2028), to investigate the distribution and form of “hydrogen” near the lunar south pole. TRITON is designed to quantify volatiles released from lunar regolith during thermogravimetry. I have been involved in this project since my time as a graduate student, contributing to its design under the constraints of limited mass, power, and volume, as well as conducting vibration and thermal testing to verify the instrument’s reliability. The second project, also at JAXA, is the development of a compact gas chromatograph–quadrupole mass spectrometer (GC-QMS) system for future planetary exploration. By coupling chromatographic separation with mass spectrometry, the instrument enables more detailed analysis of complex organic and volatile compounds than mass spectrometry alone, extending the scientific reach of future landers and rovers. Beyond the instrumentation itself, I am also working to establish a data-analysis approach, building on the principal component analysis (PCA) method that Dr. Michael L. Wong (Carnegie) presented in an earlier colloquium, to distinguish biotic from abiotic organic signatures using our own instrument data. The third project, underway at UMD and NASA GSFC, concerns the adaptation of Orbitrap (a Fourier-transform electrostatic ion trap mass spectrometer) technology for space applications. Orbitrap offers exceptionally high mass resolution and accuracy compared to conventional space-flight mass spectrometers, which is expected to broaden the range of possible in-situ measurements, including the identification of unambiguous organics and even the detection of “biosignatures”. Most recently, I have been working on CORALS ETU, an instrument being tested in the Arevalo Lab. Together, these efforts reflect a broader research theme of advancing mass spectrometer technology to meet the evolving scientific demands of solar system exploration. In this talk, I will present my motivation, contributions, and current status of each project, as well as the shared technical challenges and synergies across them.

Click here if you would like to meet with the speaker.

Deb Jaisi, University of Delaware

September 25, 2026 at 11:00 am (ESJ 1215)

Barbara Romanowicz, University of California, Berkeley

October 9, 2026 at 11:00 am (ESJ 1215)

Marcin Chwała, Wrocław University of Science and Technology and University of Maryland - College Park

October 23, 2026 at 11:00 am (ESJ 1215)

Cecilia Sanders, University of Maryland - College Park

October 30, 2026 at 11:00 am (ESJ 1215)

Apatites (Ca-phosphate group minerals) that form at low temperatures through the assembly of Ca ions and phosphate ions dissolved in water can incorporate oxygen-sensitive trace elements into their mineral structure in a way that is highly resistant to resetting even over hundreds of millions of years. That means, potentially, that apatite biominerals (bones, teeth, shells), chemical sediments (ooids, peloids), and early-forming cements and intraclasts in shallowly-buried pockets of sediment pore fluid can all record information about gradients in oxygen depletion and metal enrichment, which in turn can inform our understanding of how living and non-living components of past environments were interacting and cycling nutrients. However, rocks formed from these low-temp "bio-mediated" and "biomineralized" apatite phases often contain bits and pieces that formed in different settings, reworked and redeposited many times over. Non-destructive, high spatial resolution methods like Raman and fluorescence micro-spectroscopy, can help us distinguish these bits and pieces and unpack their formation histories in minute detail. Here, I'll present the application of these methods to a range of different apatite minerals to demonstrate their efficacy for distinguishing apatite of known oxic and anoxic origins. Then, I'll turn to apatites with unknown and more complex paleoredox histories and discuss the implications for the origins and drivers of phosphate mineralization therein. Finally, I'll discuss some open research questions to which I am applying these methods now and in the near future.

Ingrid Romero, Smithsonian National Museum of Natural History

November 13, 2026 at 11:00 am (ESJ 1215)

Gabriella Weiss, UMBC and NASA GSFC

November 20, 2026 at 11:00 am (ESJ 1215)

Lee Kump, Pennsylvania State University

December 18, 2026 at 11:00 am (ESJ 1215)

Jessica Warren, University of Delaware

February 5, 2027 at 11:00 am (ESJ 1215)

Dawn Sumner, University of California, Davis

February 12, 2027 at 11:00 am (ESJ 1215)

Tanja Bosak, Massachussetts Institute of Technology

February 19, 2027 at 11:00 am (ESJ 1215)

Scott Lakeram, Smithsonian National Museum of Natural History

March 12, 2027 at 11:00 am (ESJ 1215)

Kaushik Mitra, University of Texas, San Antonio

April 2, 2027 at 11:00 am (ESJ 1215)

Rachel Laker, Hanover College

April 9, 2027 at 11:00 am (ESJ 1215)

Clara Chan, University of Delaware

April 16, 2027 at 11:00 am (ESJ 1215)

Robert Hazen, Carnegie Earth and Planets Laboratory

April 23, 2027 at 11:00 am (ESJ 1215)

The coordinator for the Colloquium Series is Dr. Cecilia Sanders.