| Scientist Emeritus|
Geology & Geophysics
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John Hayes (emeritus, retired director of NOSAMS), maintains a program of research in isotopic biogeochemistry. Since 1998, it has resulted in many peer-reviewed publications which are listed in the bibliography below. Topics include studies of carbon- and hydrogen-isotopic fractionations imposed by phytoplankton and other microorganisms, paleoenvironmental studies based on sedimentary isotopic and organic-geochemical records, studies of the anaerobic oxidation of methane in marine sediments, the long-term record of 13C in sedimentary organic carbon, and developments in stable-isotopic analytical techniques. On-going research supported by non-NOSAMS funds includes many of those topics as well as studies of 14C as an inverse tracer for fossil-fuel-derived organic materials in modern environments (with T. Eglinton and C. Reddy) and studies of the transport and sedimentation of biomarkers of paleoclimatic interest (with T. Eglinton and J. McManus).
Papers and Data Online
- "Fractionation of the isotopes of carbon and hydrogen in biosynthetic processes (pdf)"
John M. Hayes, 23 August 2001
A chapter which will appear in Stable Isotopic Geochemistry, John W. Valley and David R. Cole (eds.). That volume will be published in the series Reviews in Mineralogy and Geochemistry, edited by Paul H. Ribbe and now published jointly by the Mineralogical Society of America and the Geochemical Society.
- "Practice and Principles of Isotopic Measurements in Organic Geochemistry (pdf) "
John M. Hayes, edited by Alex Sessions, Revision 2, August 2002,
Teaching notes related to isotopic analyses includes updated versions of "Practice and Principles of Isotopic Measurements in Organic Geochemistry," notes regarding primary standards of stable-isotopic abundances, a derivation and explanation of "Limits on the Precision of Mass Spectrometric Measurements of Isotope Ratios," a discussion of uncertainties in blank-corrected isotopic analyses, and some recent notes regarding the definition of delta and why not to call that variable "del."
"An Introduction to Isotopic Calculations (pdf)" provides a more detailed introduction to isotopic calculations. It includes explicit derivations of various Rayleigh-distillation approximations, evaluation of the related errors, and discussions of the following modes of isotopic fractionation: Reversible reaction, closed system; Irreversible reaction, closed system; Reversible reaction, open system (product lost); Reversible or irreversible reaction, open system at steady state; and Irreversible reaction, open system (product accumulated).
- Carbon-isotopic records from the paper: John M. Hayes, Harald Strauss, and Alan J. Kaufman. The Abundance of 13C in Marine Organic Matter and Isotopic fractionation in the Global Biogeochemical Cycle of Carbon During the Past 800 Ma. Chemical Geology 161, 103-125 (1999). Two formats are available.
- Comma-separated values. These are three separate, short files. They work very well if opened using a spreadsheet program. They can also be opened using a text editor. If the latter approach is taken, special care is necessary, since blank cells (marked by adjacent commas) might be easily overlooked. The filenames are kcenrecs, pzrecs, and nprecs and cover the Cretaceous and Cenozoic, the Jurassic through Cambrian, and the Neoproterozoic, respectively.
- A WinZip-compressed Excel-97 spreadsheet. This spreadsheet does not include any embedded formulas (all of the calculations are reported in the text of the paper) but does preserve a bit of formatting (Greek characters, for example) that is lost in the csv files.
Last updated: May 23, 2013