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Malak Tfaily
Joint Appointment

Dr. Tfaily is an ecosystem scientist in the Environmental Transformations and Interactions group and joint appointment at the University of Arizona. Her overarching research interests revolve around integrating multidisciplinary science to implement field- and laboratory-based investigations to advance understanding of how carbon responds to global change and the underlying microbial mechanisms and plant-microbe interactions that determine its response. She examines these relationships in both terrestrial and aquatic habitats and brings environmental chemistry research to collaborations with microbial ecologists and modelers in a systems approach. Her training as an analytical chemist provided her the unusual opportunity to learn and apply multi-omics techniques, including metabolomics and ultra-sensitive chemical characterization to further advance her capability to identify the molecules and mechanisms that are the correlative basis of ecosystem carbon cycling science and illuminate this dark matter. Additionally, her approaches are integrative and readily translatable across biomes, diverse ecological settings, and the agricultural/wildland interface.

Research Interests

  • Soil organic matter composition
  • Metabolomics and mass spectrometry
  • Controls on organic matter transformation and degradation
  • Biotic (microbial) and abiotic factors
  • Greenhouse gas emissions


  • PhD in Analytical Chemistry, Florida State University
  • BS in General Chemistry, Lebanese University

Awards and Recognition

  • The Team Award for Excellence, The University of Arizona (2020)
  • Certificate of Achievement, Scientist and Engineer Development Program, PNNL (2018)
  • Building Relationship Versatility, Social Styles at Work Certificate of Achievement, PNNL (2018)
  • Certificate of Achievement, Crucial Conversations Training, PNNL (2018)
  • Director’s Award for Outstanding Performance, PNNL (2015)
  • Director’s Award for Outstanding Performance, PNNL (2014)
  • The Dorothy and Russel Johnsen Dissertation Award Nominee, Florida State University (2012)
  • Outstanding Teaching Assistant Award Nominee, Florida State University (2011)
  • Best Teaching Assistant Award for Upper Classes Laboratory, Florida State University (2010)
  • Outstanding Teaching Assistant Award Nominee, Florida State University (2008)

Affiliations and Professional Service

  • American Geophysical Union (2009 – Present)
  • Peer Reviewer, Scientific reports; Geoderma; JGR-Biogeosciences; Science of the Total environment; Environmental Chemistry; Ecohydrology; Environmental Earth Sciences; Environmental Science and Technology; Water; Frontiers in Microbiology; Applied and Environmental Microbiology, Agronomy, and Journal of Agricultural and Food Chemistry (2011– Present) 
  • Soil Society of America (2019 – Present)
  • Panel Member, Student Engagement and Career Development and the Faculty Fellows Program Enterprises & Careers On-Campus: Tour of the Ecosystem Genomics Initiative, The University of Arizona (2019)
  • Panel Member, Women in STEM, COECYT-Sonora, Mexico (State Council of Sciences and Technology), The University of Arizona (2019)
  • Organizer, Professional Development Workshop for Students and Faculty, Ecosystem Genomics Initiative, The University of Arizona (2018)
  • Ad-hoc Reviewer: National Science Foundation, Geobiology and Low-Temperature Geochemistry (2019)
  • Ad-hoc Reviewer Johnson & Johnson Women in STEM2D, UA’s internal limited submission competition (2019)
  • Co-Chair, “Cross-divisional symposium: A Multiscale Approach to Identifying Abiotic and Biotic Interactions That Shape C Dynamics in the Soil-Atmosphere Continuum and across Latitudes,” Soil Society of America (2019)
  • Co-Chair, “Symposium: Linking Genes to Terrestrial Carbon and Nutrient Cycling: Experiments, Modeling, and Scaling” (2019)
  • Chair, “Symposium: From Genes to Ecosystems: Linking Structural and Functional Genomics to the Structure and Function of the Entire Ecosystem,” American Geophysical Union (2018)



Aminitabrizi R., R.M. Wilson, J.D. Fudyma, S. Hodgkins, H.M. Heyman, V. Rich, and S. Saleska, et al. 2020. "Controls on Soil Organic Matter Degradation and Subsequent Greenhouse Gas Emissions Across a Permafrost Thaw Gradient in Northern Sweden." Frontiers in Earth Science 8. PNNL-SA-156978. doi:10.3389/feart.2020.557961

Lybrand, R. A., J. Fedenko, M. Tfaily, and S. Rao. 2020. “Soil Properties and Biochemical Composition of Ground-Dwelling Bee Nests in Agricultural Settings.” Soil Science Society of America Journal 84 (4): 1139-1152.

Rue, G. P., J. P. Darling, E. Graham, M. M. Tfaily, and D. M. McKnight. 2020. “Dynamic Changes in Dissolved Organic Matter Composition in a Mountain Lake under Ice Cover and Relationships to Changes in Nutrient Cycling and Phytoplankton Community Composition.” Aquatic Sciences 82 (1).

Xu J., S. Roley, M. Tfaily, R.K. Chu, and J.M. Tiedje. 2020. "Organic amendments change soil organic C structure and microbial community but not total organic matter on sub-decadal scales." Soil Biology and Biochemistry 150. PNNL-SA-155812. doi:10.1016/j.soilbio.2020.107986

Zhao Q., S.J. Callister, A.M. Thompson, R.K. Kukkadapu, M. Tfaily, L.M. Bramer, and N. Qafoku, et al. 2020. "Strong mineralogic control of soil organic matter composition in response to nutrient addition across diverse grassland sites." Science of Total Environment 736. PNNL-SA-144529. doi:10.1016/j.scitotenv.2020.137839


Clair G., S.M. Reehl, K.G. Stratton, M.E. Monroe, M. Tfaily, C.K. Ansong, and J.E. Kyle. 2019. "Lipid Mini-On: Mining and ontology tool for enrichment analysis of lipidomic data." Bioinformatics 35, no. 21:4507-4508. PNNL-SA-142630. doi:10.1093/bioinformatics/btz250

Fudyma J.D., J.E. Lyon, R. Aminitabrizi, H. Gieschen, R.K. Chu, D.W. Hoyt, and J.E. Kyle, et al. 2019. "Untargeted metabolomic profiling of Sphagnum fallax reveals novel antimicrobial metabolites." Plant Direct 3, no. 11:Article No. e00179. PNNL-SA-146621. doi:10.1002/pld3.179

Garcia Arredondo M., C.R. Lawrence, M.S. Schulz, M.M. Tfaily, R.K. Kukkadapu, M.E. Jones, and K.E. Boye, et al. 2019. "Root-driven weathering impacts on mineral-organic associations in deep soils over pedogenic time scales." Geochimica et Cosmochimica Acta 263. PNNL-SA-137958. doi:10.1016/j.gca.2019.07.030

Hopple A.M., L. Pfeifer-Meister, C.A. Zalman, J.K. Keller, M. Tfaily, R.M. Wilson, and J. Chanton, et al. 2019. "Does dissolved organic matter or solid peat fuel anaerobic respiration in peatlands?." Geoderma 349. PNNL-SA-145430. doi:10.1016/j.geoderma.2019.04.040

Kane, E. S., T. J. Veverica, M. M. Tfaily, E. A. Lilleskov, K. M. Meingast, R. K. Kolka, A. L. Daniels, and R. A. Chimner. 2019. “Reduction-Oxidation Potential and Dissolved Organic Matter Composition in Northern Peat Soil: Interactive Controls of Water Table Position and Plant Functional Groups.” Journal of Geophysical Research: Biogeosciences 124 (11): 3600-3617.

Lacroix, R. E., M. M. Tfaily, M. McCreight, M. E. Jones, L. Spokas, and M. Keiluweit. 2019. “Shifting Mineral and Redox Controls on Carbon Cycling in Seasonally Flooded Mineral Soils.” Biogeosciences 16 (13): 2573-2589.

Nuñez, J. R., S. M. Colby, D. G. Thomas, M. M. Tfaily, N. Tolic, E. M. Ulrich, J. R. Sobus, T. O. Metz, J. G. Teeguarden, and R. S. Renslow. 2019. “Evaluation of in Silico Multifeature Libraries for Providing Evidence for the Presence of Small Molecules in Synthetic Blinded Samples.” Journal of Chemical Information and Modeling 59 (9): 4052-4060.

Rivas-Ubach A., Y. Liu, A.L. Steiner, J. Sardans, M.M. Tfaily, G.R. Kulkarni, and Y. Kim, et al. 2019. "Atmo-ecometabolomics: a novel atmospheric particle chemical characterization methodology for ecological research." Environmental Monitoring and Assessment 191, no. 2:Article No. 78. PNNL-SA-118888. doi:10.1007/s10661-019-7205-x

Saup, C. M., S. R. Bryant, A. R. Nelson, K. D. Harris, A. H. Sawyer, J. N. Christensen, M. M. Tfaily, K. H. Williams, and M. J. Wilkins. 2019. “Hyporheic Zone Microbiome Assembly Is Linked to Dynamic Water Mixing Patterns in Snowmelt-Dominated Headwater Catchments.” Journal of Geophysical Research: Biogeosciences 124 (11): 3269-3280.

Sengupta, A., J. Indivero, C. Gunn, M. M. Tfaily, R. K. Chu, J. Toyoda, V. L. Bailey, N. D. Ward, and J. C. Stegen. 2019. “Spatial Gradients in the Characteristics of Soil-Carbon Fractions Are Associated with Abiotic Features but Not Microbial Communities.” Biogeosciences 16 (19): 3911-3928.

Shen Y., R. Zhao, N. Tolic, M. Tfaily, E.W. Robinson, R.M. Boiteau, and L. Pasa Tolic, et al. 2019. "Online supercritical fluid extraction mass spectrometry (SFE-LC-FTMS) for sensitive characterization of soil organic matter." Faraday Discussions 218. PNNL-SA-141115. doi:10.1039/C9FD00011A

Tfaily M., R.M. Wilson, H.M. Brewer, R.K. Chu, H.M. Heyman, D.W. Hoyt, and J.E. Kyle, et al. 2019. "Single-throughput complementary high-resolution analytical techniques for characterizing complex natural organic matter mixtures." Journal of Visualized Experiments. PNNL-SA-138197. doi:10.3791/59035


Zhou, C., Y. Liu, C. Liu, Y. Liu, and M. M. Tfaily. 2019. “Compositional Changes of Dissolved Organic Carbon During Its Dynamic Desorption from Hyporheic Zone Sediments.” Science of the Total Environment 658: 16-23.

Bhattacharyya A., A. Campbell, M.M. Tfaily, Y. Lin, R.K. Kukkadapu, W. Silver, and P.S. Nico, et al. 2018. "Redox fluctuations control the coupled cycling of iron and carbon in tropical forest soils." Environmental Science & Technology 52, no. 24:14129-14139. PNNL-SA-135734. doi:10.1021/acs.est.8b03408

Bottos E.M., D.W. Kennedy, E.B. Romero, S.J. Fansler, J.M. Brown, L.M. Bramer, and R.K. Chu, et al. 2018. "Dispersal Limitation and Thermodynamic Constraints Govern Spatial Structure of Permafrost Microbial Communities." FEMS Microbiology Ecology 94, no. 8:fiy110. PNNL-SA-130968. doi:10.1093/femsec/fiy110

Boye K.E., A.M. Herrmann, M.V. Schaefer, M.M. Tfaily, and S. Fendorf. 2018. "Discerning Microbially Mediated Processes During Redox Transitions in Flooded Soils Using Carbon and Energy Balances." Frontiers in Environmental Science 6. PNNL-SA-134588. doi:10.3389/fenvs.2018.00015

Graham E.B., A.R. Crump, D.W. Kennedy, E.V. Arntzen, S.J. Fansler, S.O. Purvine, and C.D. Nicora, et al. 2018. "Multi 'omics comparison reveals metabolome biochemistry, not microbiome composition or gene expression, corresponds to elevated biogeochemical function in the hyporheic zone." Science of the Total Environment 642. PNNL-SA-133671. doi:10.1016/j.scitotenv.2018.05.256

Li, L., Z. L. He, M. M. Tfaily, P. Inglett, and P. J. Stoffella. 2018. “Spatial-Temporal Variations of Dissolved Organic Nitrogen Molecular Composition in Agricultural Runoff Water.” Water Research 137: 375-383.

Orton D.J., M.M. Tfaily, R.J. Moore, B.L. Lamarche, X. Zheng, T.L. Fillmore, and R.K. Chu, et al. 2018. "A Customizable Flow Injection System for Automated, High Throughput and Time Sensitive Ion Mobility Spectrometry and Mass Spectrometry Measurements." Analytical Chemistry 90, no. 1:737-744. PNNL-SA-128111. doi:10.1021/acs.analchem.7b02986

Pracht L., M.M. Tfaily, B. Ardissono, and R.B. Neumann. 2018. "Molecular characterization of organic matter mobilized from Bangladeshi aquifer sediment: tracking carbon compositional change during microbial utilization." Biogeosciences 15, no. 6:1733-1747. PNNL-SA-133552. doi:10.5194/bg-15-1733-2018

Reynolds, L. L., K. Lajtha, R. D. Bowden, M. M. Tfaily, B. R. Johnson, and S. D. Bridgham. 2018. “The Path from Litter to Soil: Insights into Soil C Cycling from Long-Term Input Manipulation and High-Resolution Mass Spectrometry.” Journal of Geophysical Research: Biogeosciences 123 (5): 1486-1497.

Stegen, J. C., T. Johnson, J. K. Fredrickson, M. J. Wilkins, A. E. Konopka, W. C. Nelson, E. V. Arntzen, W. B. Chrisler, R. K. Chu, S. J. Fansler, E. B. Graham, D. W. Kennedy, C. T. Resch, M. Tfaily, and J. Zachara. 2018. “Influences of Organic Carbon Speciation on Hyporheic Corridor Biogeochemistry and Microbial Ecology.” Nature Communications 9 (1).

Stegen, J. C., T. Johnson, J. K. Fredrickson, M. J. Wilkins, A. E. Konopka, W. C. Nelson, E. V. Arntzen, W. B. Chrisler, R. K. Chu, S. J. Fansler, E. B. Graham, D. W. Kennedy, C. T. Resch, M. Tfaily, and J. Zachara. 2018. “Publisher Correction: Influences of Organic Carbon Speciation on Hyporheic Corridor Biogeochemistry and Microbial Ecology (Nature Communications (2018) doi: 10.1038/S41467-018-02922-9).” Nature Communications 9 (1).

Tfaily, M. M., N. J. Hess, A. Koyama, and R. D. Evans. 2018. “Elevated [CO2] Changes Soil Organic Matter Composition and Substrate Diversity in an Arid Ecosystem.” Geoderma 330: 1-8.

Tfaily M.M., R.M. Wilson, W.T. Cooper, J.E. Kostka, P.J. Hanson, and J. Chanton. 2018. "Vertical Stratification of Peat Pore Water Dissolved Organic Matter composition in a peat bog in Northern Minnesota." Journal of Geophysical Research. Biogeosciences 123, no. 2:479-494. PNNL-SA-132063. doi:10.1002/2017JG004007

Wilson R.M., and M. Tfaily. 2018. "Advanced Molecular Techniques Provide New Rigorous Tools for Characterizing Organic Matter Quality in Complex Systems." Journal of Geophysical Research. Biogeosciences 123, no. 6:1790-1795. PNNL-SA-138120. doi:10.1029/2018JG004525

Wilson R.M., and M.M. Tfaily. 2018. "Advanced Molecular Techniques Provide New Rigorous Tools for Characterizing Organic Matter Quality in Complex Systems." Journal of Geophysical Research. Biogeosciences 123, no. 6:1790-1795. PNNL-SA-135802. doi:10.1029/2018JG004525

Yao Q., Z. Li, Y. Song, J. Wright, X. Guo, S.G. Tringe, and M.M. Tfaily, et al. 2018. "Community Proteogenomics Reveals the Systemic Impact of Phosphorus Availability on Microbial Functions in Tropical Soil." Nature Ecology & Evolution 2, no. 3:499-509. PNNL-SA-131384. doi:10.1038/s41559-017-0463-5


Bailey V.L., A.P. Smith, M.M. Tfaily, S.J. Fansler, and B. Bond-Lamberty. 2017. "Differences in Soluble Organic Carbon Chemistry in Pore Waters Sampled from Different Pore Size Domains." Soil Biology and Biochemistry 107. PNNL-SA-118268. doi:10.1016/j.soilbio.2016.11.025

Dalcin Martins P., D.W. Hoyt, S. Bansal, C. Mills, M.M. Tfaily, B.A. Tangen, and R.G. Fincchiaro, et al. 2017. "Abundant carbon substrates drive extremely high sulfate reduction rates and methane fluxes in Prairie Pothole Wetlands." Global Change Biology 23, no. 8:3107-3120. PNNL-SA-120033. doi:10.1111/gcb.13633

Dohnalkova A., M.M. Tfaily, A.P. Smith, R.K. Chu, A.R. Crump, C.J. Brislawn, and T. Varga, et al. 2017. "Molecular and Microscopic Insights into the Formation of Soil Organic Matter in a Red Pine Rhizosphere." Soils 1, no. 1:Article No. 4. PNNL-SA-128886. doi:10.3390/soils1010004

Fox P.M., P.S. Nico, M.M. Tfaily, K. Heckman, and J.A. Davis. 2017. "Characterization of Natural Organic Matter in Low-Carbon Environments: Extraction and Analytical Approaches." Organic Geochemistry 114. PNNL-SA-123194. doi:10.1016/j.orggeochem.2017.08.009

Graham E.B., J.C. Stegen, A.R. Crump, C.T. Resch, S.J. Fansler, E.V. Arntzen, and D.W. Kennedy, et al. 2017. "Organic carbon thermodynamics elucidate spatiotemporal mechanisms governing hyporheic zone biogeochemical cycling." In Proceedings of the Subsurface Biogeochemical Research and Terrestrial Ecosystem Science Joint Meeting April 25-26, 2017, Potomac, Maryland. Washington, District Of Columbia:US Department of Energy, Office of Biological and Environmental Research. PNNL-SA-125130.

Graham E.B., M.M. Tfaily, A.R. Crump, A.E. Goldman, L.M. Bramer, E.V. Arntzen, and E.B. Romero, et al. 2017. "Carbon inputs from riparian vegetation limit oxidation of physically bound organic carbon via biochemical and thermodynamic processes." Journal of Geophysical Research. Biogeosciences 122, no. 12:3188-3205. PNNL-SA-125144. doi:10.1002/2017JG003967

Rue G., N. Rock, R.S. Gabor, J. Pitlick, M.M. Tfaily, and D.M. Mcknight. 2017. "Concentration-discharge relationships during the recession of an extreme flood in the Boulder Creek Watershed: stability of major base cation concentrations contrasts with decreases in concentration and changes in chemical quality of dissolved organic material." Water Resources Research 53, no. 7:5276-5297. PNNL-SA-120916. doi:10.1002/2016WR019708

Staley C., A.P. Ferrieri, M.M. Tfaily, Y. Cui, R.K. Chu, P. Wang, and J.B. Shaw, et al. 2017. "Diurnal Cycling of Rhizosphere Bacterial Communities is Associated with Shifts in Carbon Metabolism." Microbiome 5. PNNL-SA-121718. doi:10.1186/s40168-017-0287-1

Tfaily M.M., R.K. Chu, J.G. Toyoda, N. Tolic, E.W. Robinson, L. Pasa Tolic, and N.J. Hess. 2017. "Sequential extraction protocol for organic matter from soils and sediments using high resolution mass spectrometry." Analytica Chimica Acta 972. PNNL-SA-125053. doi:10.1016/j.aca.2017.03.031

Tolic N., Y. Liu, A.V. Liyu, Y. Shen, M.M. Tfaily, E.B. Kujawinski, and K. Longnecker, et al. 2017. "Formularity: Software for Automated Formula Assignment of Natural and Other Organic Matter from Ultra-High Resolution Mass Spectra." Analytical Chemistry 89, no. 23:12659-12665. PNNL-SA-128094. doi:10.1021/acs.analchem.7b03318

Truex M.J., B.D. Lee, C.D. Johnson, N. Qafoku, J.E. Szecsody, J.E. Kyle, and M.M. Tfaily, et al. 2017. Conceptual Model of Iodine Behavior in the Subsurface at the Hanford Site. PNNL-24709 Rev. 2. Richland, WA: Pacific Northwest National Laboratory. Conceptual Model of Iodine Behavior in the Subsurface at the Hanford Site

Walker L.R., M.M. Tfaily, J.B. Shaw, N.J. Hess, L. Pasa Tolic, and D.W. Koppenaal. 2017. "Unambiguous Identification & Discovery of Bacterial Siderophores by Direct Injection 21 Tesla Fourier Transform Ion Cyclotron Resonance Mass Spectrometry." Metallomics 9, no. 1:82-92. PNNL-SA-121375. doi:10.1039/c6mt00201c

Wilson R.M., M.M. Tfaily, V. Rich, J.K. Keller, S.D. Bridgham, C. Medvedeff Zalman, and L. Meredith, et al. 2017. "Hydrogenation of Organic Matter as a Terminal Electron Sink Sustains High CO2:CH4 Production Ratios During Anaerobic Decomposition." Organic Geochemistry 112. PNNL-SA-127483. doi:10.1016/j.orggeochem.2017.06.011


Hodgkins S., M.M. Tfaily, D.C. Podgorski, C. McCalley, S. Saleska, P.M. Crill, and V. Rich, et al. 2016. "Elemental composition and optical properties reveal changes in dissolved organic matter along a permafrost thaw chronosequence in a subarctic peatland." Geochimica et Cosmochimica Acta 187. PNNL-SA-115139. doi:10.1016/j.gca.2016.05.015

Stegen J.C., A.H. Hurlbert, B. Bond-Lamberty, X. Chen, C.G. Anderson, R.K. Chu, and F. Dini-Andreote, et al. 2016. "Aligning the Measurement of Microbial Diversity with Macroecological Theory." Frontiers in Microbiology 7. PNNL-SA-122085. doi:10.3389/fmicb.2016.01487

Stegen J.C., J.K. Fredrickson, M.J. Wilkins, A. Konopka, W.C. Nelson, E.V. Arntzen, and W.B. Chrisler, et al. 2016. "Groundwater-Surface Water Mixing Shifts Ecological Assembly Processes and Stimulates Organic Carbon Turnover." Nature Communications 7. PNNL-SA-111962. doi:10.1038/ncomms11237

Tolic N., M.M. Tfaily, Y. Shen, R.K. Chu, T.L. Fillmore, R. Zhao, and K.J. Bloodsworth, et al. 2016. "Soil Organic Matter (SOM): Mass Spectrometry Data Analysis." In Encyclopedia of Soil Science, Third Edition, edited by R Lal. Boca Raton, Florida:CRC Press. PNNL-SA-117244. doi:10.1081/E-ESS3-120053757

Wilson R.M., A.M. Hopple, M.M. Tfaily, S. Sebestyen, C.W. Schadt, L. Pfeifer-Meister, and C. Medvedeff, et al. 2016. "Stability of a peatland carbon to rising temperatures." Nature Communications 7. PNNL-SA-118747. doi:10.1038/ncomms13723


Tfaily M.M., R.K. Chu, N. Tolic, K.M. Roscioli, C.R. Anderton, L. Pasa-Tolic, and E.W. Robinson, et al. 2015. "Advanced solvent based methods for molecular characterization of soil organic matter by high-resolution mass spectrometry." Analytical Chemistry 87, no. 10:5206-5215. PNNL-SA-107718. doi:10.1021/acs.analchem.5b00116