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Karen Casciotti

Title:Assistant Professor
Primary Affiliation:Department of Environmental Earth System Science
Other Affiliations:Earth Systems, E-IPER
Office Location:Y2E2 143
Phone:(650) 721-5545
E-mail:kcasciot@stanford.edu

Research

My research focuses on nitrogen cycle biogeochemistry, including how nitrate, nitrite, and nitrous oxide (N2O) are produced and consumed in ocean waters. Nitrate and nitrite are important nutrients for marine photosynthesis, and N2O is a climatically important trace gas. I take an interdisciplinary approach to these questions, applying tools from stable isotope geochemistry, geochemical modeling, microbiology and molecular biology.

Teaching

I teach Marine Chemistry (EESS 152/252), Marine Stable Isotopes (EESS 249), and co-teach Measurements in Earth Systems (EESS 212)

Professional Activities

Executive Committee AGU/Ocean Sciences Section 2013-present

Program Committee for the Ocean Sciences Meeting in 2014 and Co-Chair in 2016.

US GEOTRACES Steering Committee January 2012-present.

Associate Editor, Limnology and Oceanography: Methods, 2006-present.

Associate Editor, Marine Chemistry, 2009-present.

Intercalibration coordinator for GEOTRACES nitrate isotope measurements, 2007-present.

Attended GEOTRACES scoping workshops for the Pacific Ocean (June 25-30, 2007) and Indian Ocean (October 24-26, 2007), implementation workshops for the Atlantic Ocean (September 22-24, 2008) and Pacific Ocean (October 1-3, 2008), intercalibration workshops (December 8-9, 2007 and December 13-14, 2008), North Atlantic Section data workshop (March 11-15, 2013), Pacific Section cruise planning meeting (April 24-26, 2013).

Reviewer for NSF (OCE CO and BO, MIP/MO, ETBC, Ecosystems, Chemistry, PIRE), as well as the following journals: Science, Nature, Nature Geoscience, ISME Journal, Environmental Microbiology, PLOS Biology, Limnology and Oceanography, Limnology and Oceanography: Methods, Global Biogeochemical Cycles, Marine Chemistry, Deep Sea Research, Applied and Environmental Microbiology, Analytical Chemistry, Progress in Oceanography, Journal of Geophysical Research, Geophysical Research Letters, Rapid Communications in Mass Spectrometry, Geochimica et Cosmochimica Acta, and two chapters for the new edition of Nitrogen in the Marine Environment.

Education

  • 1995 B.S. Environmental Engineering Science, California Institute of Technology
  • 1998 M.S. Oceanography, UCSD Scripps Institution of Oceanography
  • 1999 M.S. Geosciences, Princeton Univeristy
  • 2002 PhD Geosciences, Princeton University

Professional Experience

  • 2011-Present Assistant Professor, Stanford University EESS Department
  • 2008-2010 Associate Scientist, Woods Hole Oceanographic Institution MC&G Department
  • 2004-2008 Assistant Scientist, Woods Hole Oceanographic Insitution MC&G Department
  • 2002-2004 NRC Postdoctoral Fellow, US Geological Survey, Reston VA

Honors & Awards

  • 2011                Terman Fellow Stanford University
  • 2008-2011      WHOI Coastal Ocean Institute Fellow
  • 2002                NRC Postdoctoral Research Associateship
  • 2001      Princeton University Harold W. Dodds Honorific Fellowship  

University Service

  • Geobiology Search Committee, 2011/2012
  • EESS Department Seminar Organizer Winter 2013

Professional Activities

  • Executive Committee AGU/Ocean Sciences Section 2013-present.
  • Program Committee for the Ocean Sciences Meeting in 2014 and Co-Chair in 2016, present.
  • US GEOTRACES Steering Committee Jan 2012-present
  • Associate Editor, Limnology and Oceanography Methods.
  • Associate Editor, Marine Chemistry
  • Intercalibration coordinator for GEOTRACES nitrate isotope measurements.
  • Attended GEOTRACES planning workshops for the Pacific Ocean (June 25-30, 2007) and Indian Ocean (October 24-26, 2007), Implementation workshops for the Atlantic Ocean (September 22-24, 2008) and Pacific Ocean (October 1-3, 2008) and Intercalibration workshops (December 8-9, 2007 and December 13-14, 2008).
  • Reviewer for NSF (OCE CO and BO, MIP/MO, ETBC, Ecosystems, Chemistry, PIRE), as well as the following journals: Proceedings of the National Academy of Sciences, PLOS Biology, Limnology and Oceanography, Limnology and Oceanography Methods, Global Biogeochemical Cycles, Marine Chemistry, Deep Sea Research, Applied and Environmental Microbiology, Environmental Microbiology, ISME Journal, Nature Geoscience, Analytical Chemistry, Progress in Oceanography, Journal of Geophysical Research, Geophysical Research Letters, Rapid Communications in Mass Spectrometry, Geochimica et Cosmochimica Acta, Methods in Enzymology, and Nitrogen in the Marine Environment.

Courses Taught

  • EESS 249 Marine Stable Isotopes Spring 2013
  • EESS 212 Measurements in Earth Systems (co-taught) Winter 2013
  • EESS 152/252 Marine Chemistry Winter 2013
  • EESS 249 Marine Stable Isotopes Spring 2012
  • EESS 212 Measurements in Earth Systems (co-taught) Winter 2012

Publications

  • Buchwald*, C. and K. L. Casciotti, 2013. Isotopic ratios of nitrite as tracers of the sources and age of oceanic nitrite. Nature Geoscience 6: 308-313.
  • Casciotti, K. L. and C. Buchwald*. 2012. Insights on the marine microbial nitrogen cycle from isotopic approaches to nitrification. Frontiers in Microbiology 3: 356.
  • Buchwald*, C., A. Santoro*, M. McIlvin, and K. L. Casciotti. 2012. Oxygen isotopic composition of nitrate and nitrite produced by nitrifying co-cultures and natural marine assemblages. Limnology and Oceanography 57: 1361-1375.
  • Noble, A. C. H. Lamborg, D. C. Ohnemus, P. J. Lam, T. J. Goepfert, C. I. Measures, C. H. Frame*, K. L. Casciotti, G. R. DiTullio, J. Jennings, and M. A. Saito. 2012. Basin-scale input of cobalt, iron, and manganese from the Benguela-Angola front to the South Atlantic Ocean. Limnology and Oceanography 57: 989-1010.
  • Saenz, J. P., E. C. Hopmans, D. Rogers*, P. Henderson, M. A. Charette, K. L. Casciotti, S. Shouten, J. S. Sinninghe-Damste, T. I. Eglinton. 2012. Distribution of anaerobic ammonia-oxidizing bacteria in a subterranean estuary. Marine Chemistry 136-137: 7-13.
  • Lunau, M., M. Voss, M. Erickson, C. Dziallas, K. L. Casciotti, and H. Ducklow. 2012. Excess nitrate loads to coastal waters reduces nitrate removal efficiency: mechanism and implications for coastal eutrophication. Environmental Microbiology doi: 10.1111/j.1462-2920.2012.02773.x.
  • Bernhard, J. M., K. L. Casciotti, M. R. McIlvin, D. J. Beaudoin, P. T. Visscher, and V. P. Edgcomb. 2012. Potential importance of physiologically diverse foraminifera in sedimentary nitrate storage and respiration. JGR Biogeosciences 117: G03002, doi: 10.1029/2012JG001949.
  • J. M. Bernhard, V. P. Edgcomb, K. L. Casciotti, M. R. McIlvin, and D. J. Beaudoin, 2012. Denitrification likely catalyzed by endobionts in an allogromiid foraminifer. ISME Journal doi:10.1038/ismej.2011.171.
  • A. E. Santoro*, C. Buchwald*, M. R. McIlvin, and K. L. Casciotti, 2011. Isotopic Signature of N2O Produced by Marine Ammonia-Oxidizing Archaea. Science 333: 1282-1285.
  • A. E. Santoro* and K. L. Casciotti, 2011. Enrichment and characterization of ammonia-oxidizing archaea from the open ocean: phylogeny, physiology, and stable isotope fractionation. ISME Journal 5: 1796-1808. 
  • T. J. Clough, L. E. Buckthought, K. L. Casciotti, F. M. Keliher, and P. K. Jones, 2011. Nitrous oxide dynamics in a braided river system, New Zealand. Journal of Environmental Quality 40: 1532-1541.
  • M. McIlvin and K. L. Casciotti, 2011. Technical updates to the bacterial method for nitrate isotopic analyses. Analytical Chemistry, 83: 1850-1856.
  • K. L. Casciotti, C. Buchwald*, A. E. Santoro*, and C. H. Frame*. 2010. Assessment of nitrogen and oxygen isotopic fractionation during nitrification and its expression in the marine environment. Methods in Enzymology 486: 253-280.
  • Rogers*, D. and K. L. Casciotti. 2010. Abundance and diversity of archaeal ammonia oxidizers in a coastal groundwater aquifer. Applied and Environmental Microbiology, 76: 7938-7948.
  • Frame*, C. H. and K. L. Casciotti. 2010. Biogeochemical controls and isotopic signatures of nitrous oxide production by a marine ammonia-oxidizing bacterium. Biogeosciences 7: 2695-2709.
  • Santoro*, A., K. L. Casciotti, and C. A. Francis. 2010. Activity, abundance, and diversity of nitrifying archaea and bacteria in the central California Current. Environmental Microbiology, 12: 1989-2006.
  • Banning*, E. C., K. L. Casciotti, and E. B. Kujawinski. 2010. Novel strains isolated from a coastal aquifer suggest a predatory role for flavobacteria. FEMS Microbiology Ecology 73: 254-270.
  • Buchwald*, C. and K. L. Casciotti. 2010. Oxygen isotopic exchange and fractionation during bacterial nitrite oxidation. Limnology and Oceanography, 55: 1064-1074.
  • Samarkin, V.A., M. T. Madigan, M. W. Bowles, K. L. Casciotti, J. C. Priscu, C. P. McKay, and S. B. Joye. 2010. Abiotic nitrous oxide emission from the hypersaline Don Juan Pond in Antarctica. Nature Geoscience 3: 341-344.
  • Casciotti, K. L., M. R. McIlvin, and C. Buchwald*. 2010. Oxygen isotopic exchange and fractionation during bacterial ammonia oxidation. Limnology and Oceanography, 55: 753-762.
  • McIlvin, M. R. and K. L. Casciotti. 2010. Fully automated system for stable isotopic analyses of dissolved nitrous oxide at natural abundance levels. Limnology and Oceanography: Methods, 8: 54-66.
  • Casciotti, K. L. 2009. Inverse Kinetic Isotope Fractionation During Bacterial Nitrite Oxidation. Geochimica et Cosmochimica Acta, 73: 2061-2076.
  • Higgins, M. B., R. S. Robinson, K. L. Casciotti, M. McIlvin, and A. Pearson. 2009. Determining the nitrogen isotopic composition of porphyrins by the denitrifier method. Analytical Chemistry 81(1): 184-192.
  • Priscu, J. C., B. C. Christner, J. E. Dore, M. B. Westley, B. N. Popp, K. L. Casciotti, and W. B. Lyons. 2008. Supersaturated N2O in a perennially ice-covered Antarctic lake: Molecular and stable isotopic evidence for a biogeochemical relict. Limnology and Oceanography, 53(6): 2438-2450.
  • Barnes, R. T., P. A. Raymond, and K. L. Casciotti. 2008. Dual isotope analyses indicate efficient processing of atmospheric nitrate by forested watersheds in the northeastern U.S. Biogeochemistry, 90(1): 15-27.
  • Sigman, D. M., K. L. Karsh, and K. L. Casciotti.  2008. Nitrogen Isotopes in the Ocean. In: Steele, J. H., Thorpe, S. A., and Turekian, K. K. (eds) Encyclopedia of Ocean Sciences pp. Academic Press, New York.
  • Casciotti, K. L., D. M. Glover, T. Trull, and D. Davies. 2008. Constraints on Nitrogen Cycling at the Subtropical North Pacific Station ALOHA from Isotopic Measurements of Nitrate and Particulate Nitrogen. Deep Sea Research II, 55: 1661-1672.
  • Dehairs, F., S. Jacquet, N. Savoye, J. Bishop, B. van Mooy, K. Buesseler, C. Lamborg, M. Elskens, P. Boyd, K. Casciotti, and W. Baeyens. 2008. Barium in Twilight Zone Suspended Matter as a Proxy for Particulate Organic Carbon Remineralization: Results from the North Pacific. Deep Sea Research II, 55: 1673-1683.
  • Trull, T.W., D. Davies, K. Casciotti. 2008. Insights into nutrient assimilation and export in naturally iron-fertilized waters of the Southern Ocean from nitrogen, carbon, and oxygen isotopes. Deep Sea Research II, 55: 820-840.
  • Casciotti, K. L. and M. R. McIlvin. 2007. Isotopic analyses of nitrate and nitrite from reference mixtures and application to Eastern Tropical North Pacific waters. Marine Chemistry, 107: 184-201.
  • Buesseler, K.O., C. H. Lamborg, P. W. Boyd, P. J. Lam, T. W. Trull, R. R. Bidigare, J. K. Bishop, K. L. Casciotti, F. Dehairs, M. Elskens, M. Honda, D. M. Karl, D. A. Siegel, M. W. Silver, D. K. Steinberg, J. Valdes, B. Van Mooy, S. Wilson. 2007. Revisiting Carbon Flux Through the Ocean’s Twilight Zone. Science, 316: 567-570.
  • Casciotti, K. L., J. K. Böhlke, M. R. McIlvin, S. J. Mroczkowski, J. E. Hannon. 2007. Oxygen isotopes in nitrite: analysis, calibration, and equilibration. Analytical Chemistry, 79(6): 2427-2436.
  • McIlvin, M and K. L. Casciotti. 2006. Method for the analysis of d18O in water. Analytical Chemistry, 78: 22377-2381.
  • Ward B. B., J. Granger, M. T. Maldonado, K. L. Casciotti, S. Harris, and M. L. Wells. 2005. Denitrification in the Hypolimnion of Permanently Ice-Covered Lake Bonney, Antarctica. Aquatic Microbial Ecology, 38 (3): 295-307.
  • Casciotti, K. L. and B. B. Ward. 2005. Phylogenetic analysis of nitric oxide reductase gene homologues from aerobic ammonia-oxidizing bacteria. FEMS Microbiology Ecology, 52:197-205.
  • C. C. Y. Chang, S. R. Silva, C. Kendall, G. Michalski, K. L. Casciotti, and S. Wankel, 2004. Preparation and Analysis of Nitrogen-bearing Compounds in Water for Stable Isotope Ratio Measurement. In: P.A. deGroot (ed) Handbook of Stable Isotope Analytical Techniques Volume 1, pp. 305-354.
  • Coplen, T. B., J. K. Böhlke, and K. L. Casciotti. 2004. Using dual bacterial denitrification to improve d15N determinations of nitrates containing mass independent 17O. Rapid Communications in Mass Spectrometry, 18: 245-250.
  • Casciotti, K. L., D. M. Sigman, and B. B. Ward. 2003. Linking Diversity and Stable Isotope Fractionation in Ammonia-Oxidizing Bacteria. Geomicrobiology Journal, 20(4): 335-353.
  • Casciotti, K. L., D. M. Sigman, M. Galanter Hastings, J. K. Böhlke, and A. Hilkert. 2002. Measurement of the Oxygen Isotopic Composition of Nitrate in Marine and Fresh Waters Using the Denitrifier Method. Analytical Chemistry, 74: 4905-4912.
  • Francis, C.A., K. L. Casciotti, and B. M. Tebo. 2002. Localization of Mn(II)-oxidizing activity and the putative multicopper oxidase, MnxG, to the exosporium of the marine Bacillus sp. strain SG-1. Archives of Microbiology 178: 450-456.
  • Casciotti, K. L. and B. B. Ward. 2001. Dissimilatory Nitrite Reductase Genes in Autotrophic Ammonia-Oxidizing Bacteria.  Applied and Environmental Microbiology, 67: 2213-2221.
  • Sigman, D. M., K. L. Casciotti, M. Andreani, C. Barford, M. Galanter, J. K. Böhlke. 2001. A Bacterial Method for the Nitrogen Isotopic Analysis of Nitrate in Marine and Fresh Waters.  Analytical Chemistry, 73: 4145-4153.
  • Sigman, D. M., and K. L. Casciotti.  2001. Nitrogen Isotopes in the Ocean. In: Steele, J. H., Thorpe, S. A., and Turekian, K. K. (eds) Encyclopedia of Ocean Sciences pp. 1884-1894. Academic Press, New York.
  • Landry, M. R., S. L. Brown, K. E. Selph, M. R. Abbott, R. M. Letelier, S. Christensen, R. R. Bidigare, and K. L. Casciotti. 2001. Initiation of the Spring Phytoplankton Increase in the Antarctic Polar Front Zone at 170º W. Journal of Geophysical Research-Oceans, 106 (C7): 13903-13915.

Advisee Degrees

  • Daniel Rogers, PhD. Graduated June 2010, MIT/WHOI Joint Program in Chemical Oceanogrphy
  • Erin Banning, PhD. Graduated June 2010, MIT/WHOI Joint Program in Biological Oceanography
  • Caitlin Frame, PhD. Defended February 2011, MIT/WHOI Joint Program in Chemical Oceanography
  • Carolyn Buchwald, PhD. Defended August 2012, MIT/WHOI Joint Program in Chemical Oceanography 

Advisee Publications

    noted by "*" in publication list above.

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