Sarah ZeichnerAssistant Professor (Arriving July 2027)

Research Focus:

Organic and isotope geochemistry; biogeochemistry; multiomics-enabled nutrient cycling; position-specific isotope analysis

Email:

szeichner@uchicago.edu

Biography

Preferred Pronouns: she/her/hers

I use molecular and isotope-based approaches to understand how organic molecules form, transform, and persist across environments from modern soils to the early solar system. My research integrates multiomics with compound-, clumped-, and position-specific isotope measurements to link molecular structure with the biochemical and abiotic processes that produce it.

A central focus of my group is position-specific isotope analysis. Because isotope fractionation is generated during individual bond-breaking and bond-forming steps, intramolecular isotope patterns can record mechanistic information that bulk measurements cannot. I develop methods to quantify these site-specific signatures, including Orbitrap mass spectrometry-based approaches, and apply them to questions spanning soils, sedimentary archives, and extraterrestrial organic matter.

I currently hold a Miller Postdoctoral Fellowship at the University of California, Berkeley, with affiliations including the Joint BioEnergy Institute (Lawrence Berkeley National Laboratory) and the Innovative Genomics Institute. I received my PhD in Geochemistry from Caltech in 2024, and I will join the University of Chicago in 2027 as an Assistant Professor in the Department of Geophysical Sciences.

Research Interests

• Position-specific and clumped isotope method development (GC/Orbitrap and LC/Orbitrap approaches)
• Multiomics approaches to connect metabolic potential with realized biogeochemical function
• Soil organic matter formation, persistence, aggregation, and mineral association
• Stable-isotope tracer experiments to quantify mechanisms and kinetics of microbial carbon cycling
• Abiotic organic synthesis in meteorites and asteroid samples
• Deep-time carbon isotope records and processes that modify preserved organic signatures (diagenesis, catagenesis, metamorphism)

Selected Publications

• Lotem, N., Rasmussen, B., Zi, J.W., Present, T.M., Bar‑On, Y.M., Zeichner, S.S., … Reconciling Archean organic‑rich mudrocks with low primary productivity before the Great Oxygenation Event. PNAS 122(2), e2417673121 (2025).
• Zeichner, S.S., Fischer, W.W., Lotem, N., Moore, K.R., Goldford, J.M., Eiler, J.M. The carbon isotopic composition of Archean kerogen and its resilience through the rock cycle. American Journal of Science 324, 8 (2024).
• Zeichner, S.S., Aponte, J.C., Bhattacharjee, S., Dong, G., Hofmann, A.E., … Polycyclic aromatic hydrocarbons in samples of Ryugu formed in the interstellar medium. Science 382(6677), 1411–1416 (2023).
• Zeichner, S.S., Chimiak, L., Elsila, J.E., Sessions, A.L., Dworkin, J.P., Aponte, J.C., … Position‑specific carbon isotopes of Murchison amino acids elucidate extraterrestrial abiotic organic synthesis networks. Geochimica et Cosmochimica Acta 355, 210–221 (2023).
• Zeichner, S.S., Nghiem, J., Lamb, M.P., Takashima, N., de Leeuw, J., Ganti, V., … Early plant organics increased global terrestrial mud deposition through enhanced flocculation. Science 371(6528), 526–529 (2021).