Isotopes and Isotopomers:

An innovative approach that examines the relative abundance of isotopomers of nitrous oxide (N2O). Isotopomers refers to the molecules that have the same chemical formula but differ with regard to the position of the trace isotope (e.g. position of 15N within the linear N-N-O molecule). Isotopomer analysis can be used to differentiate nitrifier from denitrifier sources of N2O in situ. On going research on isotopomers has been conducted at the Kellogg Biological Station LTER affiliated with Michigan State University, and has included work at the Luquillo Experimental Forest LTER in Puerto Rico and at the Sevilleta LTER in New Mexico.


Indigenous proteins can be retained within fossils >53,000 yr BP and are more robust than DNA, which allows for molecular records farther back in time. In particular, osteocalcin has advantages over other proteins due to its relatively high abundance in modern bones (1-2 mg/g) and the potential for exceptional preservation because of its association with bone’s hydroxyapatite mineral phase. This offers opportunities for comparing survivorship between osteocalcin and DNA in fossil bones, relating mineral characteristics to the diagenetic state of osteocalcin and establish reliable screening tools that could contribute to protein sequencing of fossils to elucidate the phylogeny of ancient mammals.

Dissolved Organic Matter (DOM):

The complexities and significance of DOM in aquatic ecosystems attracts research worldwide. In collaboration with Stroud Water Research Center and others, our goal is to determine the contributions of monomeric and polymeric DOM to stream ecosystem metabolism within a river network using a series of 13C tracer additions directly to stream segments, and follow the incorporation of DOM into bacterial-C with 13C-lipids. This final goal will be completed using a GC interfaced to a stable isotope ratio MS.

Dissolved Oxygen Stable Isotopes:

Real-time, near continuous measurements of aquatic metabolism may be measured to quantify the relative importance of episodic primary production events in coastal marine and lacustrine ecosystems using a Prism II mass spectrometer combined with a membrane inlet system. The membrane inlet system, which employs an impermeable membrane that selects for the diffusion of gases but is impermeable to liquid water, has a wide range of uses for the future of in situ isotope analyses.


Laboratory Instrumentation:

Multi-collector GV Instruments Isoprime Mass Spectrometer interfaced with a continuous flow Trace Gas Inlet System

VG Prism Series II Isotope Ratio Mass Spectrometer interfaced with a HP 5890 Series II Gas Chromatograph

GV Instruments Isoprime Mass Spectrometer interfaced with a EuroVector Elemental Analyzer 3000 Series and an Agilent 6890 Series Gas Chromatograph

HP 5890 Series II Gas Chromatograph interfaced with a HP 5972 Series Mass Selective Detector

Department of Zoology    
203 Natural Science Building
Michigan State University
East Lansing, MI 48824