Research Interests

Michael Singleton uses his background in isotope hydrology and geochemistry to address current national security threats from toxic chemicals and nuclear materials. His research spans a broad range of interests, including predicting the hydrological response of alpine groundwater systems to climate change, tracking contaminants from agriculture and legacy nuclear material production in groundwater systems, developing geolocation signatures of nuclear materials, and establishing forensic signatures of toxic chemicals.

Singleton manages LLNL’s stable isotope ratio mass spectrometry laboratory, where scientists measure precise natural abundance ratios of hydrogen, carbon, nitrogen, oxygen, and sulfur in nearly any material or phase. His current work includes analyzing the isotopic compositions of solutes such as nitrate in natural waters, oxygen isotopic compositions of nuclear materials, and stable isotope signatures of toxic substances and chemical warfare agents. His group also developed novel, compact noble gas mass spectrometry systems for hydrology and national security applications and recently demonstrated the first thermogravimetry-isotope ratio infrared spectroscopy system for measuring the isotope compositions of adsorbed and chemisorbed water on minerals.

Ph.D., Geochemistry, Washington University, 2002

B.S., Geology with a minor in Chemistry, Southern Methodist University, 1997

1. Oerter, E.J., M.J. Singleton, and M.L. Davisson (2018), Hydrogen and oxygen stable isotope dynamics of hyper-saline and salt-saturated aqueous solutions Geochimica et Cosmochimica Acta 238: 316-328.
2. Visser A., J.E. Moran, M.J. Singleton, and B.K. Esser (2018), Importance of river water recharge to the San Joaquin Valley groundwater system. Hydrological Processes 32:1202–1213.
3. Erik Oerter, Michael Singleton, and Lee Davisson (2017), Hydrogen and oxygen stable isotope signatures of goethite hydration waters by thermogravimetry-enabled laser spectroscopy, Chemical Geology 475, 14–23.
4. Visser, A., J. E. Moran, Darren Hillegonds, M. J. Singleton, Justin T. Kulongoski, Kenneth Belitz, and B. K. Esser (2016), Geostatistical analysis of tritium, groundwater age and other noble gas derived parameters in California, Water Research 91, 314–330.
5. Segal, D. C., Moran, J. E., Visser, A., Singleton, M. J., and Esser, B. K. (2014), Seasonal variation of high elevation groundwater recharge as indicator of climate response, Journal of Hydrology, doi: 10.1016/j.jhydrol.2014.10.051.
6. Visser, A., Singleton, M.J., Hillegonds, D.J., Velsko, C.A., Moran, J.E., and Esser, B.K. (2013), A Membrane Inlet Mass Spectrometer for Noble Gases at Natural Abundances in Gas and Water Samples, Rapid Communications in Mass Spectrometry 27, 2472–2482.
7. Null K. A., Dimova N. T., Knee K. L., Esser B. K., Swarzenski P. W., Singleton M. J., and Paytan A. (2012), Submarine Groundwater Discharge-Derived Nutrient Loads to San Francisco Bay: Implications to Future Ecosystem Changes, Estuaries and Coasts 35 (5), 1299–1315.
8. Volpe, A.M and M.J. Singleton (2011), Stable Isotopic Characterization of Ammonium Metavanadate (NH4VO3), Forensic Science International 209 (1–3), 96–101, doi: 10.1016/j.forsciint.2011.01.005.
9. Singleton, M. J., and J. E. Moran (2010), Dissolved noble gas and isotopic tracers reveal vulnerability of groundwater in a small, high-elevation catchment to predicted climate changes, Water Resources Research 46, W00F06, doi:10.1029/2009WR008718.
10. Singleton M. J., Esser B. K., Moran J. E., Hudson G. B., McNab W. W., and Harter T. (2007) Saturated zone denitrification: Potential for natural attenuation of nitrate contamination in shallow groundwater under dairy operations. Environmental Science and Technology 41 (3), 759–765.
11. Singleton, M.J., K. Maher, D.J. DePaolo, M.E. Conrad, and P.E. Dresel (2006), Dissolution rates and vadose zone drainage from strontium isotope measurements of groundwater in the Pasco Basin, WA unconfined aquifer, Journal of Hydrology 326, 39–58.
12. Singleton, M.J., K.N. Woods, M.E. Conrad, D.J. DePaolo, and P.E. Dresel (2005), Tracking sources of unsaturated zone and groundwater nitrate contamination using nitrogen and oxygen stable isotopes at the Hanford Site, Washington, Environmental Science and Technology 39 (10), 3563–3570.
13. Singleton, M.J., E.L. Sonnenthal, M.E. Conrad, D.J. DePaolo, and G.W. Gee (2004), Multiphase reactive transport modeling of stable isotope fractionation in unsaturated zone pore water and vapor: Application to seasonal infiltration events at the Hanford Site, WA. Vadose Zone Journal 3, 775–785.
14. Singleton, M.J. and R.E. Criss (2004), Symmetry of hydrothermal flows in the Comstock Lode mining district, Nevada: evidence for longitudnal convective rolls in geologic systems, Journal of Geophysical Research 109, B03205, doi:10.1029/2003JB002660.
15. Singleton, M.J. and R.E. Criss (2002), Effects of Normal Faulting on Fluid Flow in an Ore-Producing Hydrothermal System, Comstock Lode, Nevada, Journal of Volcanology and Geothermal Research 115, 437–450.

• NNSA Defense Programs Award of Excellence, 2018
• LLNL Director’s S&T Award, 2015
• Science and Technology, PLS Directorate Award, 2015
• NNSA Defense Programs Award of Excellence, 2014
• Excellence in Publication, PLS Directorate Award, 2013