UC Davis Plant Sciences


Dr. Joy Matthews leads the team at the SIF. She joined the facility in January 2009 and has several years of experience maintaining mass spectrometers and developing stable isotope techniques. She oversees solid sample processing and maintains the laboratory information management system used by the facility. She received her PhD from Old Dominion University in Norfolk, Virginia where she used oxygen and carbon isotopes to investigate estuarine dissolved organic matter cycling.

Dr. Chris Yarnes coordinates compound-specific analysis by GC-IRMS and LC-IRMS as well as 34S analysis. Prior to joining the SIF, Chris managed stable isotope laboratories at New Mexico State University and the University of Washington. Chris has a PhD in Ecology from New Mexico State University where he studied the biochemistry of trophic interactions.


Research & Publications

Dr. Rick Doucett oversees trace gas analysis (e.g., DIC, CO2, CH4, nitrate, N2 & N2O). Prior to arriving at SIF, Rick managed the stable isotope laboratory at Northern Arizona University for over 10 years. Rick received his PhD in Biology from the University of Waterloo in Canada where he used C, N, S (and more recently, H) isotopes to investigate freshwater food-webs. He enjoys trail running, rock climbing, whitewater kayaking, and drinking wine.
Elvira Delgado joined the SIF in April 2007. She does sample analysis and data reduction of 13C/12C and 15N/14N in solid samples and 18O/16O and D/H in water samples. Customers can contact Elvira regarding isotope analysis of hydrogen and oxygen in water. She received her MS in analytical chemistry from UC Davis for studying the decomposition pathways of small hydrocarbons on titanium foil. Elvira enjoys gardening, cooking, teaching, playing with textiles, reading and being outdoors.
Julian Herszage received a PhD in Chemistry from the Universidad de Buenos Aires in Argentina. He joined the SIF in 2013 and he assists with compound specific sample preparation, DOC analysis, and general lab maintenance. Prior to joining the SIF, Julian managed the Agroecology Lab in the Plant Sciences Department; before that he was postdoctoral researcher in the UC Davis Enology Department and in the Scripps Institution of Oceanography at UC San Diego.
Nicole Leff joined the SIF in July 2012 as a Junior Specialist. She received her Bachelors of Science in Forensic Chemistry at Northern Arizona University in May 2011 and has since done additional graduate coursework in Forensics. Her current duties include preparing standards and samples, setting up runs on the solid sample mass spectrometers, creating templates for runs on the solid sample EA-IRMS systems, importing customer samples into the lab's database, and general laboratory maintenance. She loves to read and play with her dog in her spare time; she also enjoys all outdoor activities, especially snowboarding.
Kate Pecsok Ewert joined the SIF in May 2009 after interning at the USGS Reston Stable Isotope Lab. She currently manages the bacterial denitrification assay and assists with trace gas preparation and analysis. Kate received her Bachelors of Science in Geological Sciences from the University of Missouri-Columbia in 2008.
Lyndi Low
Gabriela Robledo
Reanna Rusnak
Emily (Ngo) Schick has been with the SIF since January 2000. She graduated in 2003 from the University of California, Davis with a Bachelors of Science in Biological Sciences. Emily is involved in many different facets of the SIF, including assisting with the EA-IRMS, bacterial denitrification preparation, and website maintenance. Emily is the person to contact regarding billing issues, including submitting purchase orders and requesting estimates or invoices.
Edward Sung joined the SIF in October 2016 after graduating from the University of California, Davis with a Bachelors of Science in Biotechnology in 2016. Edward’s main responsibilities at SIF include processing received customer samples, setting up the solid sample mass spectrometers for sample runs, and bacterial denitrification preparations. He enjoys doing Kendo, playing ultimate frisbee and relaxing with origami.
Irene Yen joined the SIF in June 2007. She received a Bachelors of Arts in Geology from UC Davis in 2001. Her current responsibilities at the SIF include preparing standards and samples, setting up solid sample runs on the mass specs, and general lab maintenance. She enjoys knitting and reading in her spare time.

e-mail: sif@ucdavis.edu | phone: 530-752-8100 | fax: 530-752-4361
UC Davis Stable Isotope Facility | Department of Plant Sciences
One Shields Avenue | Davis, California, 95616 | USA