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Caroline A. Masiello

Professor of Earth, Environmental and Planetary Sciences

I study the Earth's carbon cycle on timescales from 5 years to 100,000 years. My main interests are in
  1. fundamental mechanisms of the carbon cycle and
  2. how humans are altering these mechanisms through combustion of fossil fuel, land use change, and erosion.
My research uses natural radiocarbon (14C, half-life 5730 years) coupled with organic geochemical tools like wet chemical extractions, 13C NMR, physical separations, chromatographic and spectroscopic studies to address problems related to carbon and climate. By combining geochemical tools with a chronometer (14C) I can answer questions about both mechanisms and timescales of carbon movement between reservoirs. I am particularly interested in problems related to the movement of carbon between fast and intermediate-cycling carbon pools, including the terrestrial biosphere, the atmosphere, rivers, and ocean sediments. New research in my lab includes the development of organic carbon oxidation state (Cox) as a tracer of Earth system processes.


Schneider, M.P.W., L.A. Pyle, K. Clark, W.C. Hockaday, C.A. Masiello, M.W.I. Schmidt (2013) A ‘Molecular Thermometer’ to estimate the charring temperature of wildfire charcoals. ES&T, 47, 11490-11495, doi: 10.1021/es401430f.

Coppola, A. I., Ziolkowski, L. A., Masiello, C. A., & Druffel, E. R. M. (2014). Aged black carbon in marine sediments and sinking particles. Geophysical Research Letters, 41(7), 2427–2433. http://doi.org/10.1002/2013GL059068

Webber, J.B.W., Corbetter, P., Semple, K.T., Ogbonnaya, U., Teel, W.S., Masiello, C.A., Fisher, Q.J., Valenza J.J. II, Song, Y.-Q., Hu, Q.  An NMR study of porous rock and biochar containing organic material (2013) Microporous and Mesoporous Materials 178, 94-98, doi: 10.1016/j.micromeso.2013.04.004.

Wiedemeier, D.B., S. Abiven, W.C. Hockaday, M. Keiluweit, M. Kleber, C.A. Masiello, A.V. McBeath, P.S. Nico, L.A. Pyle, M.P.W. Schneider, R.J. Smernik, G.L.B. Wiesenberg, M.W.I. Schmidt (2015) Aromaticity and the degree of aromatic condensation of chars. Organic Geochemistry, 78, 135-143, DOI: 10.1016/j.orggeochem.2014.10.002.

Brewer, C.E., Chuang, V.J., C.A. Masiello, H. Gonnermann, X. Gao, B. Dugan, L.E. Driver, P. Panzacchi, K. Zygourakis, C.A.Davies (2014) New approaches to measuring biochar density and porosity. Biomass & Bioenergy, 66, 176-185, doi: 10.1016/j.biombioe.2014.03.059.

Masiello, C.A., Dugan, B., Brewer, C.E., Spokas, K., Novak, J.M., Liu, Z., Sorrenti, G. Biochar effects on Soil Hydrology. In Biochar for Environmental Management, ed. Johannes Lehmann, published by Earthscan. in press, 2014.

Lehmann, J., M. Rillig, J. Thies, C.A. Masiello, W.C. Hockaday, and D. Crowley (2011) Biochar effects on soil biota -- a review.  Soil Biology and Biochemistry, 43, 1812-1836, doi: 10.1016/j.soilbio.2011.04.022.

Lehmann, J., M. Rillig, J. Thies, C.A. Masiello, W.C. Hockaday, and D. Crowley (in press) Biochar effects on soil biota -- a review.  Soil Biology and Biochemistry.

Sorrenti, G., C.A. Masiello, M. Toselli.  Biochar interferes with kiwifruit nutrition in calcareous soil.  In press, Geoderma.

Sorrenti, G., C.A. Masiello, B. Dugan, M. Toselli.  Biochar physico-chemical properties as affected by environmental exposure.  In press, Science of the Total Environment.

Barnes, R.T., M.E. Gallagher, C.A. Masiello, Z. Liu, B. Dugan (2014) Biochar-induced changes in hydraulic conductivity and dissolved nutrient fluxes constrained by laboratory experiments. PLOS One, DOI: 10.1371/journal.pone.0108340.

Gallagher, M.E., W.C. Hockaday, C.A. Masiello, S. Snapp, C.P. McSwiney, J.A. Baldock. (2011) Biochemical Disincentives to Fertilizing Cellulosic Ethanol Crops. Environmental Science and Technology.

Gao, X., and C.A. Masiello. ”Chapter 19: Analysis of biochar porosity by pycnometry”, in Methods of Biochar Analysis for Environmetal Applications, edited by Balwant Singh, Marta Camps, and Johannes Lehmann, in revision.

Gao, X., H.Y. Cheng, I. Del Valle, S. Liu, C.A. Masiello, J.J. Silberg.  Charcoal disrupts soil microbial communication through multiple mechanisms.  In review, Environmental Science and Technology.

Williams, E.K., B.E. Rosenheim, A.P. McNichol, C.A. Masiello (2014) Charring and non-additive chemical reactions during ramped pyrolysis: applications to the characterization of sedimentary and soil organic material.  Organic Geochemistry, 77, 106-114, DOI: 10.1016/j.orggeochem.2014.10.006.

Pyle, L. A., Hockaday, W. C., Boutton, T., Zygourakis, K., Kinney, T. J., & Masiello, C. A. (2015). Chemical and Isotopic Thresholds in Charring: Implications for the Interpretation of Charcoal Mass and Isotopic Data. Environmental Science and Technology, 49(24), 14057–14064. DOI: 10.1021/acs.est.5b03087

 Zeng, F.-W., C.A. Masiello, and W.C. Hockaday (2011)  Controls on the origin and cycling of riverine dissolved inorganic carbon in the Brazos River, Texas. Biogeochemistry. doi:10.1007/s10533-010-9501-y.

Gallagher, M.E., C.A. Masiello, W.C. Hockaday, S. Snapp, C.P. McSwiney, and J.A. Baldock (2014)  Controls on the oxidative ratio of net primary production in agricultural ecosystems. Biogeochemistry, 121(3), 581-594, DOI: 10.1007/s10533-014-0024-9.

Dong, L., *W.C. Hockaday, C.A. Masiello, P.J.J. Alvarez (2011) Earthworm avoidance of biochar can be mitigated by wetting.  Soil Biology and Biochemistry, 43, 1732-1737, doi: 10.1016/j.soilbio.2011.04.019. 

Gao, X., L.E. Driver, I. Kasin, C.A. Masiello, B. Dugan, and M. Ohlson.  Effect of environmental exposure on charcoal density and porosity in a boreal forest. In preparation.

Hockaday, W.C., M.E. Gallagher, C.A. Masiello, J.A. Baldock, C.M. Iversen, R.J. Norby.  Elevated atmospheric carbon dioxide concentrations cause an increased soil carbon oxidation state:  implications for future carbon sinks.  In revision, JGR-Biogeosciences.

Masiello, C. A., & Louchouarn, P. (2013). Fire in the Ocean. Science, 340(6130), 287–288. doi:10.1126/science.1237688.

*Kinney, T.J., C.A. Masiello, B. Dugan, *W.C. Hockaday, *M.R. Dean, K. Zygourakis, and *R.T. Barnes.  Hydrologic properties of biochars produced at different temperatures. Biomass and Bioenergy, 41, 34-43, doi: 10.1016/j.biombioe.2012.01.033.

Liu, Z., Dugan, B., Masiello, C. A., & Barnes, R. T. (2016). Impacts of biochar concentration and particle size on hydraulic conductivity and DOC leaching of biochar–sand mixtures. Journal of Hydrology, 533, 461–472. http://doi.org/10.1016/j.jhydrol.2015.12.007

Hockaday, W.C., C.A. Masiello, J.T. Randerson, R.J. Smernik, J.A. Baldock, O.A. Chadwick, J.W. Harden (2009)  The measurement of soil carbon oxidation state and oxidative ratio by nuclear magnetic resonance.  Journal of Geophysical Research-Biogeosciences, 114, G02014, doi: 10.1029/2008JG000803.

Sun, H., W.C. Hockaday, C.A. Masiello, and K. Zygourakis.  Multiple controls on the chemical and physical structure of biochars. Industrial & Engineering Chemistry Research, 51(9), 3587-3597, doi: 10.1021/ie201309r.

Koarashi, J., *W.C. Hockaday, C.A. Masiello, and S.E. Trumbore (2012) Nature and dynamics of decadally cycling carbon in subsurface soils. JGR-Biogeosciences, 117, G03033, doi:10.1029/2012JG002034.

Valdez, Z., W.C. Hockaday, C.A. Masiello, M.E. Gallagher, G.P. Robertson, Nitrogen fertilizer and harvesting intensity influence the accrual of soil carbon and nitrogen stocks in switchgrass cropping systems.  In review, Global Change Biology-Bioenergy.

LeCroy, C., C.A. Masiello, J.A. Rudgers, W.C. Hockaday, J.J. Silberg, Nitrogen, biochar, and mycorrhizae: alteration of the symbiosis and oxidation of the char surface. Soil Biol. Biochem., 58, 248-254, doi: 10.1016/j.soilbio.2012.11.023.

Sun, H., C. Brewer, C.A. Masiello, and K. Zygourakis. Nutrient Transport in Soils Amended with Biochar: A transient model with two stationary phases and intraparticle diffusion (2015) Industrial Engineering and Chemistry Research, 54(16), 4123-4135, DOI: 10.1021/ie503893t.

Gao, X., Norwood, M., Frederick, C., McKee, A., Masiello, C. A., & Louchouarn, P. (2016). Organic geochemical approaches to identifying formation processes for middens and charcoal-rich features. Organic Geochemistry, 94(C), 1–11. DOI: 10.1016/j.orggeochem.2016.01.007

Spokas, K.A., J.M. Novak, C.A. Masiello, M.G Johnson, E.C. Colosky, J.A. Ippolito, C. Trigo (2014) Physical disintegration of biochar: an overlooked process. Environmental Science and Technology Letters, 1, 326-332, doi: 10.1021/ez500199t.

 Bell-Dereske, L., X. Gao, C.A. Masiello, R. Sinsabaugh, S. Emery, J.A. Rudgers. Plant-fungal symbiosis affects litter decomposition during primary succession.  In review, Oikos.

Masiello, C.A., Y. Chen, X. Gao, S. Liu, S. Cheng, M.R. Bennett, J.A. Rudgers, D.S. Wagner, K. Zygourakis, J.J. Silberg (2013) Pyrolysis temperature determines biochar effects on microbial communication.  ES&T, 47, 11496-11503, doi: 10.1021/es401458s.

Vidonish, J.E., K. Zygourakis, C.A. Masiello, X. Gao, J. Mathieu, P.J.J. Alvarez.  Pyrolytic treatment and fertility enhancement of soils contaminated with heavy hydrocarbons.  In press, ES&T

Nguyen, B.T., J. Lehmann, W.C. Hockaday, S. Joseph, C.A. Masiello (2010) Temperature sensitivity of black carbon decomposition and oxidation.  Environmental Science and Technology, 44(9), 3324-3331, doi: 10.1021/es903016y.

Vidonish, J., K. Zygourakis, C.A. Masiello, G. Sabadell, P.J.J. Alvarez. Thermal treatment of hydrocarbon-impacted soils: A review of technology innovation for sustainable remediation.  In review, Engineering.

Kane, E.S., W.C. Hockaday, M.R. Turetsky, C.A. Masiello, D.W. Valentine, B.P. Finney, J.A. Baldock (2010) Topographic controls on black carbon accumulation in Alaskan black spruce forest soils:  implications for organic matter dynamics. Biogeochemistry, 100, 39-56. doi: 10.1007/s10533-009-9403-z.

Santin, C., Doerr, S. H., Kane, E. S., Masiello, C. A., Ohlson, M., Rosa, J. M., et al. (2016). Towards a global assessment of pyrogenic carbon from vegetation fires. Global Change Biology, 22(1), 76–91. DOI: 10.1111/gcb.12985.

Hatton, P.-J., S. Chatterjee, T. Filley, K. Dastmalchi, A.F. Plante, S. Abiven, X. Gao, C.A. Masiello, S.W. Leaveitt, K.J. Nadelhoffer, R.E. Stark, J.A. Bird. Tree taxa and pyrolysis temperature interact to control the efficacy of pyrogenic organic matter formation.  In review, Biogeochemistry Letters.

Cheng, H.-Y., C.A. Masiello, G.N. Bennett, J.J. Silberg, Using volatile gas production to report on horizontal gene transfer dynamics in soil.  In review, Environmental Science and Technology.

Schreiner, K.M., T.R. Filley, R.A. Blanchette, B.B. Bowen, R.D. Bolskar, W.C. Hockaday, C.A. Masiello, and J.W. Raebiger (2009) White-Rot Basidiomycete-mediated Decomposition of C60 Fullerol.  Environmental Science and Technology, 43(9), 3162-3168.

Worrall, F., G.D. Clay, C.A. Masiello, G. Mynheer.  Estimating the oxidative ratio of the global terrestrial biosphere carbon – the global terrestrial carbon sink has been underestimated (2013) Biogeochemistry, 115, 23-32, doi: 10.1007/s10533-013-9877-6.

Gao, Xiaodong; Masiello, Caroline A; Analysis of biochar porosity by pycnometry.  Biochar: A Guide to Analytical Methods 2017: 132

Liu, Zuolin; Dugan, Brandon; Masiello, Caroline A; Gonnermann, Helge M; Biochar particle size, shape, and porosity act together to influence soil water properties.  PloS one, 12 2017: e0179079

Santín, Cristina; Doerr, Stefan H; Merino, Agustin; Bucheli, Thomas D; Bryant, Rob; Ascough, Philippa; Gao, Xiaodong; Masiello, Caroline A; Carbon sequestration potential and physicochemical properties differ between wildfire charcoals and slow-pyrolysis biochars.  Scientific reports, 7 2017: 11233

Gao, Xiaodong; Driver, Laura E; Kasin, Isabella; Masiello, Caroline A; Pyle, Lacey A; Dugan, Brandon; Ohlson, Mikael; Effect of environmental exposure on charcoal density and porosity in a boreal forest.  Science of the Total Environment, 592 2017: 316-325

Gallagher, Morgan E; Liljestrand, Frasier L; Hockaday, William C; Masiello, Caroline A; Plant species, not climate, controls aboveground biomass O2: CO2 exchange ratios in deciduous and coniferous ecosystems.  Journal of Geophysical Research: Biogeosciences, 122 2017: 2314-2324

Bell‐Dereske, Lukas; Gao, Xiaodong; Masiello, Caroline A; Sinsabaugh, Robert L; Emery, Sarah M; Rudgers, Jennifer A; Plant–fungal symbiosis affects litter decomposition during primary succession.  Oikos, 126 2017: 801-811

Suciu, Loredana G; Griffin, Robert J; Masiello, Caroline A; Regional background O 3 and NO x in the Houston–Galveston–Brazoria (TX) region: a decadal-scale perspective.  Atmospheric Chemistry and Physics, 17 2017: 6565-6581

Pyle, Lacey A; Magee, Kate L; Gallagher, Morgan E; Hockaday, William C; Masiello, Caroline A; Short‐Term Changes in Physical and Chemical Properties of Soil Charcoal Support Enhanced Landscape Mobility.  Journal of Geophysical Research: Biogeosciences, 122 2017: 3098-3107

Valdez, Zachary P; Hockaday, William C; Masiello, Caroline A; Gallagher, Morgan E; Robertson, G Philip; Soil Carbon and Nitrogen Responses to Nitrogen Fertilizer and Harvesting Rates in Switchgrass Cropping Systems.  BioEnergy Research, 10 2017: 456-464

Pourhashem, Ghasideh; Rasool, Quazi Z; Zhang, Rui; Medlock, Kenneth B; Cohan, Daniel S; Masiello, Caroline A; Valuing the air quality effects of biochar reductions on soil NO emissions.  Environmental science & technology, 51 2017: 9856-9863

 Zeng, F.-W. and C.A. Masiello (2010) CO2 evasion from two subtropical rivers in North America.  Biogeochemistry. doi: 10.1007/s10533-010-9417-6.

 Masiello, C.A., M. E. Gallagher, J. T. Randerson, R. M. Deco, and O. A. Chadwick (2008), Evaluating two experimental approaches for measuring ecosystem carbon oxidation state and oxidative ratio, Journal Of Geophysical Research-Biogeosciences, 113, G03010, doi: 10.1029/2007JG000534.

Hammes, K., M. W. I. Schmidt, R. J. Smernik, L. A. Currie, W. P. Ball, T. H. Nguyen, P. Louchouarn, S. Houel, O. Gustafsson, M. Elmquist, G. Cornelissen, J. O. Skjemstad, C.A. Masiello, J. Song, P. Peng, S. Mitra, J. C. Dunn, P. G. Hatcher, W. C. Hockaday, D. M. Smith, C. Hartkopf-Froeder, A. Boehmer, B. Luer, B. J. Huebert, W. Amelung, S. Brodowski, L. Huang, W. Zhang, P. M. Gschwend, D. X. Flores-Cervantes, C. Largeau, J. N. Rouzaud, C. Rumpel, G. Guggenberger, K. Kaiser, A. Rodionov, F. J. Gonzalez-Vila, J. A. Gonzalez-Perez, J. M. de la Rosa, D. A. C. Manning, E. Lopez-Capel, and L. Ding (2007), Comparison of quantification methods to measure fire-derived (black/elemental) carbon in soils and sediments using reference materials from soil, water, sediment and the atmosphere, Global Biogeochemical Cycles, vol 21; doi: 10.1029/2006GB002914.

Czimczik, C. I., and C.A. Masiello (2007), Controls on black carbon storage in soils, Global Biogeochemical Cycles, 21.

Schmidt, M.W.I., and C.A. Masiello (2007), Interdisciplinary Intercomparison of Black Carbon Analysis in Soil and Sediment, Eos Trans. AGU, 88, 344, doi:10.1029/2007EO350006.

Masiello, C.A. (2007), Carbon cycle - Quick burial at sea, Nature, 450, 360-361.

Treseder, K. K., M. S. Torn, and C.A. Masiello (2006), An ecosystem-scale radiocarbon tracer to test use of litter carbon by ectomycorrhizal fungi, Soil Biology & Biochemistry, 38, 1077-1082.

Randerson, J. T., C.A. Masiello, C. J. Still, T. Rahn, H. Poorter, and C. B. Field (2006), Is carbon within the global terrestrial biosphere becoming more oxidized? Implications for trends in atmospheric O-2, Global Change Biology, 12, 260-271.

Basile-Doelsch, I., R. Amundson, W. E. E. Stone, C. A. Masiello, J. Y. Bottero, F. Colin, F. Masin, D. Borschneck, and J. D. Meunier (2005), Mineralogical control of organic carbon dynamics in a volcanic ash soil on La Reunion, European Journal of Soil Science, 56, 689-703.

Mayorga, E., A. K. Aufdenkampe, C.A. Masiello, A. V. Krusche, J. I. Hedges, P. D. Quay, J. E. Richey, and T. A. Brown (2005), Young organic matter as a source of carbon dioxide outgassing from Amazonian rivers, Nature, 436, 538-541.

 Baldock, J. A., C.A. Masiello, Y. Gélinas, and J. I. Hedges (2004), Cycling and composition of organic matter in terrestrial and marine ecosystems, Marine Chemistry, 92, 39-64, 10.1016/j.marchem.2004.06.016.

Wakeham, S. G., J. Forrest, C.A. Masiello, Y. Gelinas, C. R. Alexander, and P. R. Leavitt (2004), Hydrocarbons in Lake Washington sediments. A 25-year retrospective in an urban lake, Environmental Science & Technology, 38, 431-439.

Masiello, C. A., O. A. Chadwick, J. Southon, M. T. Torn, and J. W. Harden (2004), Weathering Controls on Mechanisms of Carbon Storage in Grassland Soils, Global Biogeochemical Cycles, 18, doi:  10.1029/2004GB002219.

 Masiello, C.A. (2004), New directions in black carbon organic geochemistry, Marine Chemistry, 92, 201-213.

Dickens, A. F., Y. Gelinas, C.A. Masiello, S. Wakeham, and J. I. Hedges (2004), Reburial of fossil organic carbon in marine sediments, Nature, 427, 336-339.

 Treseder, K. K., C.A. Masiello, J. L. Lansing, and M. F. Allen (2004), Species-specific measurements of ectomycorrhizal turnover under N-fertilization: combining isotopic and genetic approaches, Oecologia, 138, 419-425.

M.W.I. Schmidt, C.A. Masiello, J.O. Skjemstad Final recommendations for reference materials in black carbon analyses.  EOS - Transactions of the American Geophysical Union, 84 2003: 582-583

 Masiello, C.A., and E. R. M. Druffel (2003), Organic and black carbon 13C and 14C through the Santa Monica Basin oxic-anoxic transition, Geophysical Research Letters, 30, doi 10.1029/2002GL015050.

Currie, L. A., B. A. Benner, J. D. Kessler, D. B. Klinedinst, G. A. Klouda, J. V. Marolf, J. F. Slater, S. A. Wise, H. Cachier, R. Cary, J. C. Chow, J. Watson, E. R. M. Druffel, C. A. Masiello, T. I. Eglinton, A. Pearson, C. M. Reddy, O. Gustafsson, J. G. Quinn, P. C. Hartmann, J. I. Hedges, K. M. Prentice, T. W. Kirchstetter, T. Novakov, H. Puxbaum, and H. Schmid (2002), A critical evaluation of interlaboratory data on total, elemental, and isotopic carbon in the carbonaceous particle reference material, NIST SRM 1649a, Journal of Research of the National Institute of Standards and Technology, 107, 279-298.

 Masiello, C.A., E. R. M. Druffel, and L. A. Currie (2002), Radiocarbon measurements of black carbon in aerosols and ocean sediments, Geochimica Cosmochimica Acta, 66, 1025-1036.

Masiello, C.A., and E. R. M. Druffel (2001), The isotope geochemistry of the Santa Clara River, Global Biogeochemical Cycles, 15, 407-416.

Masiello, C.A., and E. R. M. Druffel (1998), Black carbon in deep-sea sediments, Science, 280, 1911-1913.

Bauer, J. E., E. R. M. Druffel, D. M. Wolgast, S. Griffin, and C.A. Masiello (1998), Distributions of dissolved organic and inorganic carbon and radiocarbon in the eastern North Pacific continental margin, Deep-Sea Res Pt Ii-Top St Oce, 45, 689-71.

Masiello, C.A., E. R. M. Druffel, and J. E. Bauer (1998), Physical controls on dissolved inorganic radiocarbon variability in the California Current, Deep-Sea Res Pt II-Top St Oce, 45, 617-642.


  • B.A. physics and mathematics (1991) Earlham College
  • M.S. Environmental Science (1993) University of North Carolina, Chapel Hill
  • Ph.D. Earth System Science (1999) University of California, Irvine
  • Center for Biological and Environmental Nanotechnology
  • Center for the Study of the Environment and Society
  • Department of BioSciences
  • Department of Chemistry
  • Environmental and Energy Systems Institute
  • Institute of Biosciences and Bioengineering
  • Shell Center for Sustainability
  • Carbon cycling, carbon sequestration, climate change, black carbon, terrestrial-river-ocean biosphere interactions
Email: masiello@rice.edu
Phone: (713) 348-5234
Office: Keith Wiess Earth Science, 206A