Assistant Professor, Marine Science Program and Earth and Ocean Sciences
Ph.D. Massachusetts Institute of Technology/Woods Hole Oceanographic Institution, 2007.
I study trace metals and their stable isotope ratios in the ocean. Metals are important nutrients for phytoplankton which support the food chain and remove carbon dioxide from the atmosphere. As part of the Geotraces project my lab will provide the first global-scale measurements of metal isotopes in seawater. With such measurements, we seek to understand the marine sources and sinks of these important elements, and to understand the biogeochemical cycling of metals in the water column. To better interpret natural data, our measurements are brought together with laboratory experiments on the fractionation of metal isotopes by biological and abiological processes, and simple theoretical models of metal isotope cycling in the oceans.
* denotes student or postdocs
John, S. 2012. Optimizing sample and spike concentrations for isotopic analysis by double-spike ICP-MS. Journal of Analytical Atomic Spectrometry, DOI: 10.1039/c2ja30215b.
Boyle, E., John, S., Abouchami, W., Adkins, J., Echegoyen-Sanz, Y., Flegal, A.R., Ellwood, M., 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., and Y.Zhao. 2012. GEOTRACES IC1 (BATS) contamination-prone trace element isotopes Cd, Fe, Pb, Zn, Cu, and Mo intercalibration. Limnology and Oceanography: Methods 10.
John, S.G. and J. Adkins. 2012. The vertical distribution of iron stable isotopes in the North Atlantic near Bermuda. Global Biogeochemical Cycles, 26: GB2034.
John, S.G., Mendez, J., Moffett, J., and J. Adkins. 2012. The flux of iron and iron isotopes from San Pedro Basin sediments. Geochimica et Cosmochimica Acta, 93: 14-29.
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.S., Jacobs, J.S., Treitel, C., James, T.L., and M.P. Montgomery. 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 B-3-Trifluoromethylphenoxy Esters, Thioesters, and Ketones. The Journal of Organic Chemistry, 77: 2819-2828.
Sivan, O., Adler, M., Pearson, A., Gelman, F., Bar-Or, I., John, S.G., and W. Eckert. 2011. Geochemical evidence for iron-mediated anaerobic oxidation of methane. Limnology and Oceanography, 56: 1536-1544.
John, S.G., and Adkins, J.F. (2010) Analysis of dissolved iron isotopes in seawater. Marine Chemistry, 116 65-76.
John, S.G., Mendez, C.B., Deng, L., Poulos, B., Kauffman, A.K.M., Kern, S., Brum, J., Polz, M.F., Boyle, E.A., and Sullivan, M.B. (2010) A simple and efficient method for concentration of ocean viruses by chemical ﬂocculation. Environmental Microbiology Reports.
John, S.G., Rouxel, O.J., Craddock, P.R., Engwall, A.M., and Boyle, E.A. (2008) Zinc stable isotopes in seafloor hydrothermal vent fluids and chimneys. EPSL, 269 (1-2) 17-28.
John, S.G., Geis, R.W., Saito, M.A., and Boyle, E.A. (2007). Zinc isotope fractionation during high-affinity an low-affinity zinc transport by the marine diatom Thalassiosira oceanica. Limnology and Oceanography 52: 2710-2714.
John, S.G., Park, J.G., Zhang, Z.T., and Boyle, E.A. (2007). The isotopic composition of some common forms of anthropogenic zinc. Chemical Geology, 245(1-2): 61-69.
MSCI 210: Oceans and Society
MSCI 313: The Chemistry of the Ocean
MSCI 599: Environmental Analyses of SC: Field Course