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Stable Isotope Research

Our laboratory has provided stable isotope data for a wide range of research projects both within and outside the Northwestern research community. One key area of study in our department employs stable isotope data to reconstruct major perturbations in the biogeochemical cycles of carbon and sulfur that occurred in the deep past. Such events record the full range of behavior of chemical cycles during ancient episodes of global climate change and provide important information for predictions of environmental change related to future global warming. Other projects focus on processes critical to the understanding of the global carbon cycle, such as the transport of carbon through various modern environments.

Former graduate student Maya Gomes and Prof. Matthew Hurtgen studied how the size of the sulfate reservoir affects the preservation of sulfur isotope signals in modern and ancient oceans taking analogy from Lake McCarrons, a modern euxinic lake near St. Paul, Minnesota. The depth profiles of sulfur isotopes (δ34S) in sulfides and sulfates in the lake water column and δ34S in acid volatile sulfur and pyrite from the lake sediment were analyzed in the stable isotope lab. The results indicated smaller differences of δ34S between sulfates and sulfides in the sediments (Δ34S ~ 5 to 10‰) despite relatively large isotopic fractionation (~ 24‰) associated with microbial sulfate reduction. The study has important implications for the studies of biogeochemistry of sulfur in modern and ancient environments. The results were published in the journal Geology (41, p. 663-666, 2013).

In addition to these exciting projects, the lab supports ongoing work of former undergraduate and graduate students who continue to collaborate with department faculty and provides analyses for other users, including academic researchers as well as commercial entities. Contact the lab manager for analysis requirements and sample submission procedure.

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