Faculty Candidate Seminar - Eva Stueeken

01/07/2016 - 12:00pm


DATE:  January 7, Thursday, 12:00 p.m. 

LOCATION: Hubbs Hall 4500 
SPEAKER: Eva Stueeken, Ph.D.
University of Washington, Seattle, and University of California, Riverside 

TITLE:  Selenium and nitrogen in deep time: hypotheses, links and open questions 

Selenium and nitrogen are both redox-sensitive elements that are most mobile under fully oxic conditions and isotopically fractionated at intermediate redox potential. They can therefore serve as proxies for the rise and fall of O2 in the atmosphere and oceans over the course of Earth’s history. While nitrogen isotopes are an established biogeochemical tool, especially for the Phanerozoic and in modern environments, selenium isotopes are just beginning to be explored. In the first part of my talk, I will present recent findings about the evolution of the biogeochemical nitrogen cycle, in particular about the antiquity of biological N2 fixation and secular trends in marine nitrate abundances in the Precambrian. In the second part, I will discuss preliminary trends in selenium isotopes that to first order support the conclusions drawn from the nitrogen record. I will end with an outlook of future research directions that may improve the utility of both proxies and tie them more closely to other biogeochemical cycles. 

Faculty Host:  Anne Pommier (pommier@ucsd.edu)
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Hubbs Hall 4500