Prof. Johnson's group focuses on environmental geochemistry, isotope geochemistry, and hydrogeology. The group is working to better understand several redox-sensitive contaminant elements, including chromium, selenium, uranium, and mercury. They develop and use methods for measurement of the stable isotopes of these and other elements as indicators of key geochemical reactions, contamination sources, and past environments on Earth.
The group uses the department's multicollector ICP-MS laboratory constantly to make these measurements and often develops or improves measurement methods.
See our more detailed web pages, including opportunities for graduate students, HERE
- Ph.D., University of California at Berkeley
- GEOL 117: The Oceans
- GEOL 118: Natural Disasters
- GEOL 370/GEOG 370/ESE 320: Water Planet/Water Crisis
- GEOL 470: Hydrogeology
- GEOL 562: Isotope Geochemistry
- GEOL 579: Isotope Hydrogeology
Additional Campus Affiliations
Wang, X., Planavsky, N. J., Hofmann, A., Saupe, E. E., De Corte, B. P., Philippot, P., ... Konhauser, K. O. (2018). A Mesoarchean shift in uranium isotope systematics. Geochimica et Cosmochimica Acta, 238, 438-452. https://doi.org/10.1016/j.gca.2018.07.024
Jemison, N. E., Shiel, A. E., Johnson, T. M., Lundstrom, C. C., Long, P. E., & Williams, K. H. (2018). Field Application of 238U/235U Measurements to Detect Reoxidation and Mobilization of U(IV). Environmental Science and Technology, 52(6), 3422-3430. https://doi.org/10.1021/acs.est.7b05162
Basu, A., Schilling, K., Brown, S. T., Johnson, T. M., Christensen, J. N., Hartmann, M., ... DePaolo, D. J. (2016). Se Isotopes as Groundwater Redox Indicators: Detecting Natural Attenuation of Se at an in Situ Recovery U Mine. Environmental Science and Technology, 50(20), 10833-10842. https://doi.org/10.1021/acs.est.6b01464
Shiel, A. E., Johnson, T. M., Lundstrom, C. C., Laubach, P. G., Long, P. E., & Williams, K. H. (2016). Reactive transport of uranium in a groundwater bioreduction study: Insights from high-temporal resolution 238U/235U data. Geochimica et Cosmochimica Acta, 187, 218-236. https://doi.org/10.1016/j.gca.2016.05.020
Wang, X., Reinhard, C. T., Planavsky, N. J., Owens, J. D., Lyons, T. W., & Johnson, T. M. (2016). Sedimentary chromium isotopic compositions across the Cretaceous OAE2 at Demerara Rise Site 1258. Chemical Geology, 429, 85-92. https://doi.org/10.1016/j.chemgeo.2016.03.006