Guaciara M. Dos Santos
Research Project Scientist VI, KCCAMS/UCI Facility
Manager of the KCCAMS/UCI Facility
Biography
Dr. Guaciara M. dos Santos is a Research Project Scientist VI at the KCCAMS/UCI Facility in the Earth System Science Department at the University of California, Irvine. She earned her Ph.D. in Applied Nuclear Physics from Federal Fluminense University in Brazil in 1999 and her M.Sc. in Laser & Spectroscopy from the same institution in 1995. Santos completed postdoctoral research at the Australian National University from 1999 to 2001, focusing on accelerator mass spectrometry techniques.
Santos joined UCI in 2002 as an Associate Specialist and has served as Manager of the KCCAMS/UCI Facility since that time. Her research centers on radiocarbon analysis and its applications to understanding the global carbon cycle, atmospheric CO2 dynamics, and paleoclimate reconstruction. She has authored over 100 peer-reviewed articles in journals including Nature Physics, Radiocarbon, and Quaternary Geochronology. Santos has secured significant funding from the National Science Foundation, including a $3.3 million grant in 2021 for the acquisition of a MICADAS system. She received the UFF "Prata da Casa" Award in 2017 for outstanding academic achievement and has been invited to speak at numerous international conferences on radiocarbon dating and environmental applications.
At UCI, Santos oversees the operation of advanced accelerator mass spectrometry equipment and manages collaborative research projects with institutions worldwide. She has mentored over 50 students and research personnel, including undergraduate researchers, graduate students, and postdoctoral scholars. Santos serves on editorial boards and scientific advisory committees for major radiocarbon conferences and contributes to peer review for leading journals in her field. Her service includes roles on the International Scientific Advisory Board for radiocarbon conferences and membership on advisory panels for national AMS laboratories.
Return to topDegrees
- Ph.D. in Apply Nuclear Physics, Federal Fluminense University, 1999
- M.Sc. in Laser & Spectroscopy, Federal Fluminense University, 1995
- Teaching Certification in General Physics, Federal Fluminense University, 1995
- B.Sc. in General physics, Federal Fluminense University, 1992
Distinctions
- UFF "Prata da Casa" Award for Outstanding Academic Achievement performance, Universidade Federal Fluminense (UFF), 2017
- LABEX OT-Med 2013, LABEX OT-Med, 2013
- NSF #MRI-2117634, National Science Foundation, 2021
- NSF #AGS/P2C2-1903687, National Science Foundation, 2019
- NSF #FY17/P2C22017, National Science Foundation, 2018
- NSF #EAR-1144888, National Science Foundation, 2012
- ANU Bridging Postdoctoral Fellow, Australia National University, 2001
- CNPq Postdoctoral Research Fellowship, Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Brazil, 1999
Areas of Expertise
- Accelerator Mass Spectrometry
- Radiocarbon Dating Applications
- Atmospheric Carbon Cycle
- Paleoclimate Sample Preparation
- Tree Ring Analysis
- Tropical Atmospheric Reconstruction
- Carbon Source Apportionment
- Phytolith Carbon Research
- MICADAS System Development
- Medieval Literature Translation
Recent Publications
- Guaciara M. Santos, Lucas G. Pereira, Ana C. Barbosa, Santiago Ancapichún, Peter van der Sleen, Pieter A. Zuidema, Peter Groenendijk, “Tropical Central African bomb radiocarbon reveals antiphase air-mass atmospheric fluxes and vegetation-growth relationships”, Science of the Total Environment, vol. 989, 2025.
- Santos, G.M., Granato-Souza, D., Ancapichún, S., Oelkers, R., Haines, H.A., De Pol-Holz, R., Andreu-Hayles, L., Hua, Q., Barbosa, A.C., “A novel post-1950 CE atmospheric 14C record for the tropics using absolutely dated tree rings in the equatorial Amazon”, Science of The Total Environment, vol. 918, pp. 170686, 2024.
- Fontana, C., López, L., Santos, G.M., Villalba, R., Hornink, B., Assis-Pereira, G., Roig, F.A., Tomazello-Filho, M., “A new chronology of Cedrela fissilis (Meliaceae) for Southern Brazil: combining classical dendrochronology and radiocarbon dating”, Dendrochronologia, vol. 85, pp. 126214, 2024.
- Griffin, J.N., Santos, G.M., Nguyen, L.D., Rodriguez, D.R., Pereira, L.G., Jaén-Barrios, N., Assis-Pereira, G., de Oliveira Barreto, N., Brandes, A.F., Barbosa, A.C., Groenendijk, P., “Demystifying the tropics: FTIR characterization of pantropical woods and their α-cellulose extracts for past atmospheric 14C reconstructions”, Science of The Total Environment, vol. 949, pp. 175010, 2024.
- Santos, G.M., Nguyen, L.D., Griffin, J.N., Nathan de Oliveira Barreto, N.D., Ortega-Rodriguez, D.R., Barbosa, A.C., Gabriel Assis-Pereira, G., “Evaluating possible sources of error in tree-ring 14C data using multiple trees across South America”, Radiocarbon, vol. 67, pp. 176-191, 2024.
- Harris, A.J.T., Santos, G.M., Malone, K.O., van der Meer, M.T.J., Riekenberg, P., Fernandes, R., “A long-term study of stable isotope ratios of fingernail keratin and amino acids in a mother-infant dyad”, American Journal of Biological Anthropology, vol. 185, pp. e25021, 2024.
- Lucas Duy Nguyen, “Evaluations of standard measurement and procedural errors for tree ring 14C analysis through multivariable data comparisons”, Radiocarbon, 2024.
- June Nakachi Griffin, “FTIR wood compounds of multiple tropical tree species”, STOTEN, 2024.
- Christopher Leong, Anita Sumi Yayi Komatsu, Jazmine M. Jr. Renteria, “Improving a cellulose extraction protocol designed to all wood types and ¹⁴C ages”, QUAGEO, 2024.
- Santos, G.M., Komatsu, A.S.Y., Jr. Renteria, J.M., Brandes, A.F.N., Leong, C.A., Collado-Fabbri, S., De Pol-Holz, R., “A universal approach to alpha-cellulose extraction for radiocarbon analysis of 14C-free to post-bomb ages”, Quaternary Geochronology, vol. 74, pp. 101414, 2023.
- Pacheco-Solana A, Oelkers R, D'Arrigo R, Santos GM, Rodriguez-Caton M, Tejedor E, Ferrero E, Fuentes AF, Maldonado C, Andreu-Hayles L, “Radiocarbon and wood anatomy as complementary tools for generating tree-ring records in Bolivia”, Frontiers in Plant Science, vol. 14, pp. 1135480, 2023.
- Oelkers, R.C., Andreu-Hayles, L., D'Arrigo, R., Pacheco-Solana, A., Rodriguez-Caton, M., Fuentes, A., Santos, G.M., Tejedor, E., Ferrero, M.E., Maldonado, C., “Recent growth increase in endemic Juglans boliviana from the tropical Andes”, Dendrochronologia, vol. 79, pp. 126090, 2023.
- Ticse-Otarola, G., Vidal, O.D., Andreu-Hayles, L., Quispe-Melgar, H.R., Amoroso, M.M., Santos, G.M., Requena-Rojas, E.J., “Age structure and climate sensitivity of a high Andean relict forest of Polylepis rodolfo-vasquezii in central Peru”, Dendrochronologia, vol. 79, pp. 126071, 2023.
- Biondi, F., Santos, G.M., Rodríguez, P.R., Sosa, P.A., “Longevity estimates of Canary palms and dragon trees by radiocarbon”, Plants, vol. 13, no. 1, pp. 45, 2023.
- Santos, G.M., Leong, C.A., Seiler, M., Grootes, P.M., Svarva, H., Nadeau, M., “Radiocarbon step-combustion oxidation and FTIR analysis of Trondheim CaCO3 precipitates of atmospheric CO2 samples: further investigations and insights”, Radiocarbon, vol. 66, pp. 1289-1301, 2023.
- Chiquetto, J.B., Leichsenring, A.R., Santos, G.M., “Socioeconomic conditions and fossil fuel CO2 in the Metropolitan Area of Rio de Janeiro”, Urban Climate, vol. 43, pp. 101176, 2022.
- Santos G.M., Albuquerque R.P., Barros C.F., Ancapichún S., Oelkers R., Andreu-Hayles L., De Faria S.M., De Pol-Holz R., Brandes A.F.N., “High-precision 14C measurements of parenchyma-rich Hymenolobium petraeum tree species confirm bomb-peak atmospheric levels and reveal local fossil-fuel CO2 emissions in the Central Amazon”, Environmental Research, vol. 214, 2022.
- Rodríguez-Morata, C., Pacheco-Solana, A., Ticse-Otarola, G., Espinoza, T.B., Crispín-DelaCruz, D.B., Santos, G.M., Morales, M.S., Requena-Rojas, E.J., Andreu-Hayles, L., “Revealing Polylepis microphylla as a suitable tree species for dendrochronology and quantitative wood anatomy in the Andean montane forests”, Dendrochronologia, vol. 76, pp. 125995, 2022.
- Rafael Perpétuo Albuquerque, “Tracking fossil fuel emissions from shipping activity deep in the amazon rainforest”, Environmental Research Journal, 2022.
Most Cited Publications
- Ingalls, A.E., Shah, S.R., Hansman, R L., Aluwihare, L.I., Santos, G.M., Druffel, E.R.M., Pearson, A., “Quantifying archaeal community autotrophy in the mesopelagic ocean using natural radiocarbon”, Proceedings of the National Academy of Sciences of the United States of America, vol. 103, pp. 6442-6447, 2006.
- Hua, Q., Turnbull, J.C., Santos, G.M., Rakowski, A.Z., Ancapichún, S., De Pol-Holz, R., Hammer, S., Lehman, S.J., Levin, I., Miller, J.B., Palmer, J.G., Turney, C.S.M., “Atmospheric Radiocarbon for The Period 1950-2019”, Radiocarbon, vol. 64, pp. 1-23, 2021.
- Santos, G.M., Southon, J., Griffin, S., Beaupre, S.R., Druffel, E.R., “Ultra small-mass 14C-AMS sample preparation and analysis at the KCCAMS Facility”, Nuclear Instruments and Methods in Physics Research Section B Beam Interactions with Materials and Atoms, vol. 259, pp. 293-302, 2007.
- Maciel, A.M.M., P.R.S. Gomes, J. Lubian, R.M. Anjos, R. Cabezas, S.B. Moraes, C. Muri, M. M. Sant'Anna, G.M. Santos, R. Liguori Neto, N. Added, N. Carlin, C. Tenreiro, “Influence of the 6,7 Li Breakup Process on the Near Barrier Elastic Scattering with Heavy Nuclei”, Physical Review C Nuclear Physics, vol. 59, pp. 2103, 1999.
- Santos, G.M., Southon, J.R., Druffel-Rodriguez, K.C., Griffin, S., Mazon, M., “Magnesium perchlorate as an alternative water trap in AMS graphite sample preparation: A report on sample preparation at KCCAMS at the University of California, Irvine”, Radiocarbon, vol. 46, pp. 165-173, 2004.
- Kramer C, Trumbore S, Fröberg M, Dozal LMC, Zhang D, Xu X, Santos GM, Hanson P, “Recent (<4 year old) Leaf Litter is Not a Major Source of Microbial Carbon in a Temperate Forest Mineral Soil”, Soil Biology and Biochemistry, vol. 42, pp. 1028-1037, 2010.
- Southon, J., Santos, G.M., Druffel-Rodriguez, K., Druffel, E., Trumbore, S., Xu, X. M., Griffin, S., Ali, S., Mazon, M., “The Keck Carbon Cycle AMS laboratory, University of California, Irvine: Initial operation and a background surprise”, Radiocarbon, vol. 46, pp. 41-49, 2004.
- Danišík, M., Shane, P., Schmitt, A.K., Hogg, A., Santos, G.M., Storm, S., Evans, N.J., Fifield, K., Lindsay, J., “Re-anchoring the late Pleistocene tephrochronology of North Island (New Zealand) based on concordant radiocarbon ages and combined 238U/230 Th disequilibrium and (U-Th)/He zircon ages”, Earth and Planetary Science Letters, vol. 349-350, pp. 240-250, 2012.
- Santos, G.M., Moore, R.B., Southon, J.R., Griffin, S., Hinger, E., Zhang, D., “AMS 14C sample preparation at the KCCAMS/UCI Facility: status report and performance of small samples”, Radiocarbon, vol. 49, no. 2, pp. 255-269, 2007.
- Grothe PR, Cobb KM, Liguori G, Di Lorenzo E, Capotondi A, Lu Y, Hai Cheng H, Edwards RL, Southon JR, Santos GM, Deocampo DM, Lynch-Stieglitz J, Chen T, Sayani HR, Townsend K, Hagos M, O'Connor G, Thompson DM, Toth LT, Conroy JL, Moore AL, “Enhanced El Niño-Southern Oscillation variability in recent decades”, Geophysical Research Letters, vol. 47, 2019.
Contact Information
Website: https://sites.uci.edu/santos/
Email: gdossant@uci.edu
Phone: +1(949) 824-9851
Address: B321 Croul Hall, University of California, Irvine, CA 92697-3100
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Last updated on 7/24/2025.