Lawrence Livermore National Laboratory



Sarah Roberts

Research Staff
Nuclear and Chemical Sciences Division


 +1 925-423-4112


DegreeDiscipline/InstitutionYear
M.S. Geology
Arizona State University
Thesis: " Stable Isotope Systematics of Dolomite Concretions and Beds from the Miocene Monterey Formation, California", Advisor: Dr. L. Paul Knauth. Area of specialization: Stable Isotope Geochemistry
1990
B.S. Geology
Arizona State University
1979

Research Interests

  • X-Ray Diffractometry – Geological and Nuclear Forensic materials
  • Stable Isotope Geochemistry
  • Environmental and Energy Research
  • Laboratory and Field Geochemical Experiments

Record of Invention

Use of colloidal silica to block fast flow paths in enhanced geothermal systems, submitted August 2010.


Publications, Reports, and Abstracts

Qu, D-X, Roberts, S.K. and Chapline, G.F. Observation of huge surface hole mobility in topological insulator Bi 0.91Sb 0.09 (111), 2013. URL: http://link.aps.org/doi/10.1103/PhysRevLett.111.176801.

Moser, D.P., Hamilton-Brehm, S., Zhang, G., Fisher, J., Hughes, K., Wheatley, A., Thomas, J., Zavarin, M., Roberts, S.K., Kryder, L., McRae, R., Howard, W., Walker, J., Federwisch, R., King, M., Friese, R., Grim, S., Amend, J., Momper, L., Lollar, B.S., Onstott, T.C., Microbial Ecology of a Regional Flow System: Deep, Aerobic, Fractured Rock Aquifers of the US Basin and Range, Presented at the AGU Fall 2013 meeting, San Francisco, CA.

Roberts, S.K., Ezzedine, S.M., Bourcier, W.L., Hunt, J.D., and Roberts, J.J. Transport of Colloidal Silica in Porous Media for Geological CO2 Sequestration. Presented at the AGU Fall 2013 meeting, San Francisco, CA.

Hunt, J.D., Ezzedine, S.M., Bourcier, W.L., and Roberts, S.K. Kinetics of the Gelation of Colloidal Silica at Geothermal Conditions, and Implications for Reservoir Modification and Management. Presented at the 2013 Stanford Geothermal Workshop, Palo Alto, CA.

Bourcier, W.L., Ezzedine, S.M., Hunt, J.D., Roberts, S.K. and Roberts, J.J. Maximizing Heat Extraction and Minimizing Water Losses in Hydrothermal Systems: A Numerical Investigation. Presented at the 2013 Stanford Geothermal Workshop, Palo Alto, CA.

Borg, L. E., Lindvall, R.E., Schorzman, K.C., Eppich, G.R., Ramon, E.C., Williams, R.W., and Roberts, S.K. (2012) Procedure for the Analysis of Yellow Cake and Uranium Ore Samples, LLNL-TM-598054, 2012.

Ezzedine, S.M., Bourcier, W.L., Hunt, J.D., Roberts, S.K., and Roberts, J.J., Enhancing the Sustainability of EGS Using Colloidal Silica Gel. Geothermal Resources Council Transactions, 2012.

Hunt, J.D., Ezzedine, S.M., Bourcier, W.L., Roberts, S.K., Kinetics of Colloidal Silica Gelation at EGS Conditions and Implications for Reservoir Modification. Geothermal Resources Council Transactions, 2012.

Moran J. E., Esser B. K., Hillegonds D., Marianne Holtz, Roberts S. K., Singleton M. J., and Visser A. Aspects of Nitrate Fate and Transport in the Salinas Valley, submitted to GRA Salt & Nitrate conference, June 2012 Fresno, CA.

Ezzedine, S.M., Hunt, J.D., Bourcier, W.L., Roberts, S.K., and Roberts, J.J. Impact of Silica Gel Deployment on Subsurface Flow and Heat Extraction from Enhanced Geothermal Systems. Presented at the 2012 Stanford Geothermal Workshop, Palo Alto, CA.

Hunt, J.D., Ezzedine, S.M., Bourcier, W.L., Roberts, S.K., and Roberts, J.J. Silica Gel Behavior Under Different EGS Chemical and Thermal Conditions: an Experimental Study. Presented at the 2012 Stanford Geothermal Workshop, Palo Alto, CA.

Moran J. E., Esser B. K., Hillegonds D., Marianne Holtz, Roberts S. K., Singleton M. J., and Visser A. California GAMA Special Study: Nitrate Fate and Transport in the Salinas Valley, pp. 38. Lawrence Livermore National Laboratory LLNL-TR-484186. (GAMA-LLNL Report, Special Studies, 2011).

Singleton M.J, Moran J.E, Esser B.K., Roberts, S.R. and Hillegonds, D.J. California GAMA Special Study: An isotopic and dissolved gas investigation of nitrate source and transport to a public supply well in Califonia's Central Valley. Submitted April 1, 2010.

Singleton M.J., Roberts, S.R., and Esser B.K. California GAMA Special Study: Nitrate and Water Isotopic Data for the San Diego Domestic Wells Project. Submitted April 14, 2010.

Pawloski, G.A., Tompson, A.F.B., Carle, S.F., Detwiler, R.L., Hu, Q., Kollet, S., Maxwell, R.M., McNab, W.W., Roberts, S.K., Shumaker, D.E., Sun, Y., and Zavarin, M. Evaluation of Hydrologic Source Term Processes for Underground Nuclear Tests in Yucca Flat, Nevada Test Site: Introduction and Executive Summary. May 2008.

Viani, B. and Roberts, S. Analysis of Four Samples of Yellow Cake and Ore via Powder X-Ray Diffraction. January 2008.

Carroll, S., Roberts, S., Criscenti, L.J., and O'Day, P.A. Surface Complexation Model for Strontium Sorption to Amorphous Silica and Goethite. Geochemical Transactions, January 18, 2008.

Roberts, S., Pawloski, G., and Raschke, K. Evaluation of Cavity Collapse and Surface Crater Formation for Selected Lawrence Livermore National Laboratory Underground Nuclear Tests – 2007, LLNL-TR-431031. Prepared for NSTec and the Department of Energy, National Nuclear Security Association, Nevada Site Office Borehole Management Program (BMP), May 2007.

Zavarin, M., Roberts, S.K., Reimus, P.W., and Johnson, M.R. Summary of Radionuclide Reactive Transport Experiments in Fractured Tuff and Carbonate Rocks from Yucca Flat, Nevada Test Site. Prepared for the UGTA Project, Department of Energy, National Nuclear Security Administration, Nevada Site Office, March 2007.

Viani, B., and Roberts, S. Analysis of 21 Samples of Yellow Cake via Powder X-Ray Diffraction, Internal LLNL report, March 2007.

Zavarin, M., Roberts, S.K., Johnson, M.R., Lindvall, R., Hu, Q., Zhao, P., Powell, B., and Pletcher, R. Radionuclide Transport in Carbonate Fractures from Yucca Flat, Nevada Test Site. Prepared for the UGTA Project, Department of Energy, National Nuclear Security Administration, Nevada Site Office, December 2006.

Morris, J., Antoun, T., Rambo, J., and Roberts, S. Containment Prospectus for the Fictitious Exercise. Internal LLNL report, October 2006.

Dixit, S., Roberts, S., Evans, K., Wolery, T., and Carroll, S. General Corrosion and Passive Film Stability FY05 Summary Report. Prepared for the Yucca Mountain Program, July 2006.

Viani, B.E., Roberts, J.J., Detwiler, R.L., Roberts, S.K., and Carlson, S.R. Simulating Injectate/Rock Chemical Interaction In Fractured Desert Peak Quartz Monzonite. Geothermal Resources Council 2005 Annual Meeting Reno, NV, June 2005.

Carlson, S.R, Roberts, J.J., Detwiler, R.L., Viani, B.E., and Roberts, S.K. Fracture Permeability Evolution in Desert Peak Quartz Monzonite. Geothermal Resources Council 2005 Annual Meeting Reno, NV, May 2005.

Zavarin, M., Johnson, M.R., Roberts, S.K., Pletcher, R., Rose, T., Kersting, A.B., Eaton, G., Hu, Q., Ramon, E., Walensky, J., and Zhao, P. Radionuclide Transport in Tuff and Carbonate Fractures from Yucca Flat, Nevada Test Site, Underground Test Area (UGTA). Prepared for the UGTA Project, Department of Energy, National Nuclear Security Administration, Nevada Site Office, 2005.

Zavarin, M., S. K. Roberts, N. Hakem, A.M. Sawvel, and Kersting, A.B. Eu(III), Sm(III), Np(V), Pu(V), and Pu(IV) Sorption to Calcite. Radiochimica Acta 93, issue 2, 93-102, 2005.

Walensky, J., Kersting, A.B., Zavarin, M., Roberts, S.K., Johnson, M.R., Zhao, P., and Ramon, E. The role of colloids and mineralogy in the transport of Pu, Np and Sm at the Nevada Test Site. Presented at the American Chemical Society meeting San Diego, March 2005.

Zhao, P., Johnson, M.R., Roberts, S.K., and Zavarin, M. Pu and Np sorption on manganese oxide minerals. Presented at the American Chemical Society meeting, San Diego, March 2005.

Roberts, S.K., Johnson, M.R., Zavarin, M., Pletcher, R., Hu, Q., Kersting, A., Ramon, E., Zhao, P., and Walensky, J. Laboratory investigation of radionuclide sorption and migration in fractured Nevada Test Site rock. Presented at the American Chemical Society meeting San Diego, March 2005.

Zavarin, M., Johnson, M.R., Roberts, S.K., Hu, Q., Zhao, P., and Kersting, A. Applying mechanistic modeling at the field scale: Radionuclide transport at the Nevada Test Site. Presented at the American Chemical Society meeting San Diego, March 2005.

Kersting, A.B., Zhao, P., Walensky, J., Roberts, S.K., Johnson, M.R., Zavarin, M., and Ramon, E. Colloid Facilitated Transport of Plutonium in Fractured Volcanic Tuff, Fall 2004 AGU abstract.

Zavarin, M., Johnson, M.R., Roberts, S.K., Pletcher, R., Kersting, A.B., Eaton, G., Hu, Q., Ramon, E., Walensky, J., and Zhao, P. Radionuclide Transport in Tuff and Carbonate Fractures from Yucca Flat, Nevada Test Site, Underground Test Area (UGTA) Task Report. October 2004.

Zhao, P., Johnson, M.R., Roberts, S.K., and Zavarin, M. Np and Pu sorption to Manganese Oxide Minerals. Underground Test Area (UGTA) Task Report, October 2004.

Viani, B., Roberts, S.K., Ridolfi, B., and Knauss, K. Progress report #3 LLNL Fibrous Fillers Project, October 2004.

Steefel C., Carroll S., Zhao P., and Roberts, S.K. Cesium Migration in Hanford Sediment: A Multi-Site Cation Exchange Model Based on Laboratory Transport Experiments. Journal of Contaminant Hydrology, Volume 67, Issues 1-4, Pages 219-246, December 2003.

Roberts, S.K., Carroll S., Steefel C., and Zhao P. Cesium Migration in the Hanford Sediment: A Multi-Site Cation Exchange Model Based on Laboratory Transport Experiments at 25 and 80 ºC. Abstract and Presentation at the Annual Geological Society of America meeting in Seattle, Washington; November, 2003.

Burton, L., Hu, M., Johnson, M., Kersting, A., Pletcher, R., Roberts, S. K., Rose, T., Zavarin, M., and Zhao, P. Investigations of Radionuclide Sorption and Migration in Fractured NTS Rocks, Poster presented at the UGTA Technical Information Exchange, Las Vegas, Nevada, April 2004.

Bruton, C., Carle, S., Daniels, J., Maxwell, R., Pawloski, G., Roberts, S. K., Shumaker, D., Tompson, A., Zavarin, M. LLNL UGTA FY04 projects, Poster presented at the UGTA Kickoff Meeting, Las Vegas, Nevada; October, 2003.

Roberts, S., Ridolfi, B., Knauss, K., and Viani, B. Fibrous Fillers Project, LLNL, Progress Report #'s 1 and 2, October 2003 and January 2004.

Carroll S., Steefel C., Roberts, S.K., and Zhao P. Cesium and Strontium Migration in Hanford Sediments: A Multi-Site Cation Exchange Model Based on Laboratory Transport Experiments. Abstract to the Euresco Conference on Geochemistry of Crustal Fluids. Seefeld, Austria, 2002.

Zavarin, M., Roberts, S., Zhao, P., Williams, R., Rose, T., Rainer, A., and Pawloski, G. High Temperature Studies of Glass Dissolution Rates Close to Saturation. Prepared for the Underground Test Area Project, U. S. Department of Energy, Nevada Operations Office, 2002.

Zavarin, M., Roberts, S., Viani, B., Pawloski, G.A., and Rose, T.P. Identification of Secondary Minerals Formed During Melt Glass Dissolution at 40 to 200ºC. Prepared for the Underground Test Area Project, U. S. Department of Energy, Nevada Operations Office, 2002.

Zavarin M., Roberts S. K., Rose T. P., and Phinney D. L. Validating Mechanistic Sorption Model Parameters and Processes for Reactive Transport in Alluvium. Internal LLNL report, May 2002.

Roberts, S.K., Bourcier, W.L., and Shaw, H.F. Aqueous dissolution kinetics of pyrochlore, zirconolite, and brannerite at 25, 50 and 75°C. Radiochimica Acta 88, 539-543 (2000).

Bourcier, W.L., Roberts, S.K., Smith, D.K., Hulsey, S., Newton, L., Sawvel, A., Bruton, C., LLNL, and Papelis, C., Um, W., Russell, C.E., and Chapman, J. Desert Research Institute, University and Community College System of Nevada. Determination of Reactive Surface Area of Melt Glass. Prepared for the UGTA Project, Department of Energy, National Nuclear Security Administration, Nevada Site Office, October 2000.

Zhao, P., Roberts, S.K., and Bourcier, W.L Technical progress report on single phase flow-through tests of ceramic waste forms for plutonium immobilization. Internal LLNL report, December 2000.

Zavarin, M., and Roberts, S. Simulating reactive transport of radiouclides at the NTS using non-electrostatic surface complexation. 221st American Chemical Society National Meeting, April 2001.

Carroll, S.A., Steefel,, C.I., Roberts, S.K., and Zhao, P. Cesium Transport in Hanford Sediments: Application of an Experimentally Based Cation Exchange Model. American Chemical Society Meeting, August 2001.

Sahai, N., Carroll, S., Roberts, S., and O'Day, P. X-Ray Absorption Spectroscopy of Strontium (II) Coordination. II. Sorption and Precipitation at Kaolinite, Amorphous Silica, and Geothite Surfaces. Journal of Colloid and Interface Science, Vol. 222, No.2, Feb 2000, pp 198-212.

Sahai N., O'Day, P., Carroll, S., and Roberts, S., EXAFS study of Sr sorption on goethite kaolinite and silica gel. American Chemical Society Meeting, 1999.

Carroll, S., Roberts, S., Hayden, C., O'Day, P., and Sahai, N. Strontium sorption to amorphous silica, kaolinite, goethite, and gibbsite. American Chemical Society Meeting, 1999.

Carroll, S., Roberts, S., O'Day, P., and Sahai, N. Sorption and precipitation of strontium at kaolinite, gibbsite, silica gel, and goethite surfaces. 7th International Conference on the Chemistry and Migration Behavior of Actinides and Fission Products in the Geosphere, 1999.

Bourcier, W., Roberts, S., and Shaw, H. Aqueous dissolution kinetics of pyrochlore, zirconolite, and brannerite at 25, 50, and 75°C. 7th International Conference on the Chemistry and Migration Behavior of Actinides and Fission Products in the Geosphere, 1999.

Roberts, S., Viani, B., and Deloach, L. Mineral Abundances in Exploratory Studies Facility Core Samples in Single-Heater Test Final report, Blair, S., Lin, W., Ramirez, A., Deloach, L., Buscheck, T., editors, Dec 1998.

Carroll, S., Roberts, S., Hayden, C., O'Day, P., and Sahai, N. Experimental Determination of Strontium Mobility as a function of Temperature, Time, and Solution Chemistry. SSRL Users Conference, 1998.

Roberts, S. and Viani, B. Determination of Mineral Abundances in Samples from the Exploratory Studies Facility, Yucca Mountain, Nevada, Using X-ray diffraction. Internal LLNL report, January 1998.

Carroll, S., Torreto, P., and Roberts, S. Strontium sorption to Goethite and Kaolinite at 25, 50 and 80°C. Internal LLNL report, 1997.

Roberts, S.K., Viani, B.E., and Phinney, D. Intracrystalline Diffusion in Clinoptilolite: Implications for radionuclide Isolation. Submitted to the International High Level Radioactive Waste Management Conference, Las Vegas, NV May, 1996.

Knauth, L.P. and Roberts, S.K. The Hydrogen and Oxygen Isotopic History of the Silurian – Permian Hydrosphere as determined by direct measurement of Fossil Water in Stable Isotope Geochemistry: A Tribute to Samuel Epstein, The Geochemical Society, Special Publication no. 3, 1991.

Knauth, L.P., and Roberts, S.K. Use of Stable Isotopes and Chemical Analyses to Determine Brine Sources in Salt Domes: Progress and Problems; Geological Society of America abstracts with programs, p A246, 1990.

Knauth, L.P. and Roberts, S.K. Stable Isotope Systematics of Dolomite Concretions and Beds from the Miocene Monterey Formation, CA; Geological Society of America abstracts with programs, p A17, 1989.

Knauth, L.P., Roberts, S.K., and Larimer, S. Isotopic Composition of Silurian Seawater; Geological Society of America abstracts with programs, 17, p 630, 1985.

London, D., Bandy, G., and Kealy, S. Metasomatic Alteration of Primary Lithium Posphates from the White Picacho Pegmatite District, Maricopa and Yavapai Counties; Geological Society of America abstracts with programs, 10, p 446, 1978.


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