On the mechanisms of sulfur isotope fractionation during microbial sulfate reduction
Contributors: Johnston, David T.; Pearson, Ann; Hansel, Colleen M.; Cavanaugh, Colleen M.; Cardoso Pereira, Inês A.; Bradley, Alexander S.
Published: 2014
Language: eng
Description: Underlying all applications of sulfur isotope analyses is our understanding of isotope systematics. This dissertation tests some fundamental assumptions and assertions, drawn from equilibrium theory and a diverse body of empirical work on biochemical kinetics, as applied to the multiple sulfur isotope systematics of microbial sulfate reduction. I take a reductionist approach, both in the questions addressed and experimental approaches employed. This allows for a mechanistic, physically consistent interpretation of geological and biological sulfur isotope records. The goal of my work here is to allow interpreters a more biologically, chemically and physically parsimonious framework to decipher the signals coded in modern and ancient sulfur isotope records.
Notes: Keywords: enzyme isotope fractionation, geomicrobial kinetic isotope effects, microbial sulfate reduction, multiple sulfur isotopes, Phanerozoic oxygen, sulfur cycle.

Thesis Ph.D. Harvard University 2014