Seth John

• Division Postdoctoral Fellow, California Institute of Technology, 2007 – 2010

Tenure Track Appointments

• Assistant Professor, University of Southern California, 2019 – 2020
• Assistant Professor, University of South Carolina, 2010 – 2014

Research, Teaching, Practice, and Clinical Appointments

• Associate Resarch Professor, Univeristy of Southern California, 2015-2019

Summary Statement of Research Interests

Trace-metals play important roles in many Earth processes. Professor John’s Marine Trace Element Laboratory (MTEL) studies the isotope geochemistry of trace-metals in order to understand how these crucial micronutrients support life in the modern ocean, and how they can be used as proxies to understand the history of biological and geological earth processes. Current and recent work includes the analysis of trace-metal stable isotope ratios (d56Fe, d66Zn, and d114Cd) in seawater and other marine samples, laboratory studies to observe how metal isotope fractionate under different experimental conditions, numerical modeling of metal isotope biogeochemical cycles in the oceans, and analysis of metal isotopes in geological reservoirs.

Research Specialties

geobiolgy, geochemistry, oceanography, metal isotopes, virology, modeling, medical sciences

Journal Article

• Isson, T. T., Love, G. D., Dupont, C. L., Reinhard, C. T., Zumberge, A. J., Asael, D., Gueguen, B., McCrow, J., Gill, B. C., Owens, J., Rainbird, R. H., Rooney, A. D., Zhao, M. Y., Stueeken, E. E., Konhauser, K. O., John, S. G., Lyons, T. W., Planavsky, N. J. (2018). Tracking the rise of eukaryotes to ecological dominance with zinc isotopes. Geobiology / John Wiley & Sons Ltd. Vol. 16 (4)
• Marsay, C. M., Lam, P. J., Heller, M. I., Lee, J. M., John, S. G. (2018). Distribution and isotopic signature of ligand-leachable particulate iron along the Geotraces GP16 East Pacific Zonal Transect. Marine Chemistry / Elsevier. Vol. 201 PubMed Web Address
• Conway, T. M., John, S. G. (2015). Biogeochemical cycling of cadmium isotopes along a high-resolution section through the North Atlantic Ocean. GEOCHIMICA ET COSMOCHIMICA ACTA. Vol. 148, pp. 269-283.
• Revels, B. N., Ohnemus, D. C., Lam, P. J., Conway, T. M., John, S. G. (2015). The isotopic signature and distribution of particulate iron in the North Atlantic Ocean. DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY. Vol. 116, pp. 321-331.
• Revels, B. N., Zhang, R., Adkins, J. F., John, S. G. (2015). Fractionation of iron isotopes during leaching of natural particles by acidic and circumneutral leaches and development of an optimal leach for marine particulate iron isotopes. GEOCHIMICA ET COSMOCHIMICA ACTA. Vol. 166, pp. 92-104.
• Fitzsimmons, J. N., Carrasco, G. G., Wu, J., Roshan, S., Hatta, M., Measures, C. I., Conway, T. M., John, S. G., Boyle, E. A. (2015). Partitioning of dissolved iron and iron isotopes into soluble and colloidal phases along the GA03 GEOTRACES North Atlantic Transect. DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY. Vol. 116, pp. 130-151.
• Cunningham, B. R., Brum, J. R., Schwenck, S. M., Sullivan, M. B., John, S. G. (2015). An Inexpensive, Accurate, and Precise Wet-Mount Method for Enumerating Aquatic Viruses. APPLIED AND ENVIRONMENTAL MICROBIOLOGY. Vol. 81 (9), pp. 2995-3000.
• Mackey, K. R., Post, A. F., McIlvin, M. R., Cutter, G. A., John, S. G., Saito, M. A. (2015). Divergent responses of Atlantic coastal and oceanic Synechococcus to iron limitation. PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA. Vol. 112 (32), pp. 9944-9949.
• Conway, T. M., John, S. G. (2015). The cycling of iron, zinc and cadmium in the North East Pacific Ocean – Insights from stable isotopes. GEOCHIMICA ET COSMOCHIMICA ACTA. Vol. 164, pp. 262-283.
• Zhang, R., John, S. G., Zhang, J., Ren, J., Wu, Y., Zhu, Z., Liu, S., Zhu, X., Marsay, C. M., Wenger, F. (2015). Transport and reaction of iron and iron stable isotopes in glacial meltwaters on Svalbard near Kongsfjorden: From rivers to estuary to ocean. EARTH AND PLANETARY SCIENCE LETTERS. Vol. 424, pp. 201-211.
• Black, J. R., John, S. G., Kavner, A. (2014). Coupled effects of temperature and mass transport on the isotope fractionation of zinc during electroplating. GEOCHIMICA ET COSMOCHIMICA ACTA. Vol. 124, pp. 272-282.
• Janssen, D. J., Conway, T. M., John, S. G., Christian, J. R., Kramer, D. I., Pedersen, T. F., Cullen, J. T. (2014). Undocumented water column sink for cadmium in open ocean oxygen-deficient zones. PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA. Vol. 111 (19), pp. 6888-6893.
• Conway, T. M., John, S. G. (2014). The biogeochemical cycling of zinc and zinc isotopes in the North Atlantic Ocean. GLOBAL BIOGEOCHEMICAL CYCLES. Vol. 28 (10), pp. 1111-1128.
• John, S. G., Conway, T. M. (2014). A role for scavenging in the marine biogeochemical cycling of zinc and zinc isotopes. EARTH AND PLANETARY SCIENCE LETTERS. Vol. 394, pp. 159-167.
• Conway, T. M., John, S. G. (2014). Quantification of dissolved iron sources to the North Atlantic Ocean. NATURE. Vol. 511 (7508), pp. 212-+.
• Conway, T. M., Rosenberg, A. D., Adkins, J. F., John, S. G. (2013). A new method for precise determination of iron, zinc and cadmium stable isotope ratios in seawater by double-spike mass spectrometry. ANALYTICA CHIMICA ACTA. Vol. 793, pp. 44-52.
• Homoky, W. B., John, S. G., Conway, T. M., Mills, R. A. (2013). Distinct iron isotopic signatures and supply from marine sediment dissolution. NATURE COMMUNICATIONS. Vol. 4
• John, S. G., Adkins, J. (2012). The vertical distribution of iron stable isotopes in the North Atlantic near Bermuda. GLOBAL BIOGEOCHEMICAL CYCLES. Vol. 26
• Mohrig, J. R., Beyer, B. G., Fleischhacker, A. S., Ruthenburg, A. J., John, S. G., Snyder, D. A., Nyffeler, P. T., Noll, R. J., Penner, N. D., Phillips, L. A., Hurley, H. L., Jacobs, J. S., Treitel, C., James, T. L., Montgomery, M. P. (2012). Does Activation of the Anti Proton, Rather than Concertedness, Determine the Stereochemistry of Base-Catalyzed 1,2-Elimination Reactions? Anti Stereospecificity in E1cB Eliminations of beta-3-Trifluoromethylphenoxy Esters, Thioesters, and Ketones. JOURNAL OF ORGANIC CHEMISTRY. Vol. 77 (6), pp. 2819-2828.
• John, S. G. (2012). Optimizing sample and spike concentrations for isotopic analysis by double-spike ICPMS. JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY. Vol. 27 (12), pp. 2123-2131.
• Boyle, E. A., John, S., Abouchami, W., Adkins, J. F., Echegoyen-Sanz, Y., Ellwood, M., Flegal, A. R., Fornace, K., Gallon, C., Galer, S., Gault-Ringold, M., Lacan, F., Radic, A., Rehkamper, M., Rouxel, O., Sohrin, Y., Stirling, C., Thompson, C., Vance, D., Xue, Z., Zhao, Y. (2012). GEOTRACES IC1 (BATS) contamination-prone trace element isotopes Cd, Fe, Pb, Zn, Cu, and Mo intercalibration. LIMNOLOGY AND OCEANOGRAPHY-METHODS. Vol. 10, pp. 653-665.
• John, S. G., Mendez, J., Moffett, J., Adkins, J. (2012). The flux of iron and iron isotopes from San Pedro Basin sediments. GEOCHIMICA ET COSMOCHIMICA ACTA. Vol. 93, pp. 14-29.
• Sivan, O., Adler, M., Pearson, A., Gelman, F., Bar-Or, I., John, S. G., Eckert, W. (2011). Geochemical evidence for iron-mediated anaerobic oxidation of methane. LIMNOLOGY AND OCEANOGRAPHY. Vol. 56 (4), pp. 1536-1544.
• John, S. G., Mendez, C. B., Deng, L., Poulos, B., Kauffman, A. K., Kern, S., Brum, J., Polz, M. F., Boyle, E. A., Sullivan, M. B. (2011). A simple and efficient method for concentration of ocean viruses by chemical flocculation. ENVIRONMENTAL MICROBIOLOGY REPORTS. Vol. 3 (2), pp. 195-202.
• Black, J. R., Crawford, J. A., John, S., Kavner, A. (2011). Redox Driven Stable Isotope Fractionation. AQUATIC REDOX CHEMISTRY. Vol. 1071, pp. 345-359.
• John, S. G., Mendez, C. B., Deng, L., Poulos, B., Kauffman, A. K., Kern, S., Brum, J., Polz, M. F., Boyle, E. A., Sullivan, M. B. (2011). A simple and efficient method for concentration of ocean viruses by chemical flocculation (vol 3, pg 195, 2011). ENVIRONMENTAL MICROBIOLOGY REPORTS. Vol. 3 (6), pp. 809-809.
• Black, J. R., John, S., Young, E. D., Kavner, A. (2010). Effect of temperature and mass transport on transition metal isotope fractionation during electroplating. GEOCHIMICA ET COSMOCHIMICA ACTA. Vol. 74 (18), pp. 5187-5201.
• John, S. G., Adkins, J. F. (2010). Analysis of dissolved iron isotopes in seawater. MARINE CHEMISTRY. Vol. 119 (1-4), pp. 65-76.
• John, S. G., Rouxel, O. J., Craddock, P. R., Engwall, A. M., Boyle, E. A. (2008). Zinc stable isotopes in seafloor hydrothermal vent fluids and chinmeys. EARTH AND PLANETARY SCIENCE LETTERS. Vol. 269 (1-2), pp. 17-28.
• John, S. G., Park, J. G., Zhan, Z., Boyle, E. A. (2007). The isotopic composition of some common forms of anthropogenic zinc. CHEMICAL GEOLOGY. Vol. 245 (1-2), pp. 61-69.
• John, S. G., Geis, R. W., Saito, M. A., Boyle, E. A. (2007). Zinc isotope fractionation during high-affinity and low-affinity zinc transport by the marine diatom Thalassiosira oceanica. LIMNOLOGY AND OCEANOGRAPHY. Vol. 52 (6), pp. 2710-2714.
• Dhungana, S., Michalczyk, R., Boukhalfa, H., Lack, J. G., Koppisch, A. T., Fairlee, J. M., Johnson, M. T., Ruggiero, C. E., John, S. G., Cox, M. M., Browder, C. C., Forsythe, J. H., Vanderberg, L. A., Neu, M. P., Hersman, L. E. (2007). Purification and characterization of rhodobactin: a mixed ligand siderophore from Rhodococcus rhodochrous strain OFS. BIOMETALS. Vol. 20 (6), pp. 853-867.
• Repeta, D. J., Hartman, N. T., John, S., Jones, A. D., Goericke, R. (2004). Structure elucidation and characterization of polychlorinated biphenyl carboxylic acids as major constituents of chromophoric dissolved organic matter in Seawater. ENVIRONMENTAL SCIENCE & TECHNOLOGY. Vol. 38 (20), pp. 5373-5378.
• John, S. G., Ruggiero, C. E., Hersman, L. E., Tung, C. S., Neu, M. P. (2001). Siderophore mediated plutonium accumulation by Microbacterium flavescens (JG-9). ENVIRONMENTAL SCIENCE & TECHNOLOGY. Vol. 35 (14), pp. 2942-2948.