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J. Kirk Cochran

Cochran
Professor

Ph.D., 1979, Yale University

kirk.cochran@stonybrook.edu

Marine geo-chemistry, use of radionuclides as geochemical tracers; diagenesis of marine sediment


 

Research Interests

My research group and I are using natural radionuclides to study Earth surface processes. The fact that different chemical elements are represented in the suite of radioactive nuclides permits studies of chemical behavior, and the property of radioactivity provides a clock with which to measure rates. Much of my recent research has focused on using naturally occurring radionuclides to determine rates of particle cycling and particulate organic carbon fluxes in the open ocean. This work has as its goal an understanding of the fate of carbon in the ocean and has been carried out in the North Atlantic, Pacific and Southern Oceans, as well as the Mediterranean Sea Radionuclides such as 234Th and 210Po provide a means of determining the export of particulate organic carbon from the upper ocean and provide information on this important aspect of the carbon cycle.

In coastal waters and estuaries, naturally occurring particle-reactive radionuclides provide tracers to determine rates of removal of contaminants from the water column and the subsequent transport and deposition of sediments and associated contaminants. Radionuclides that tend to remain in solution, such as the Ra isotopes, serve as tracers of submarine groundwater discharge to the coastal ocean. These applications are part of ongoing projects in New York’s coastal lagoons (Jamaica Bay, Great South Bay) and in Long Island Sound. A related area of research in regional settings is the health and resiliency of the area’s salt marshes. Marshes are increasingly being lost and we seek to understand the causes of loss. I am applying an integrated approach to examine both the biogeochemical and physical dynamics of natural and restored salt marshes.

In addition to broad applications of natural radionuclides to recent Earth surface processes, I am collaborating with colleagues in the Stony Brook Dept. of Geosciences, the American Museum of Natural History and Brooklyn College (CUNY) to characterize the geochemical setting of the Late Cretaceous (~70 Ma) Western Interior Seaway of North America and oceanographic conditions prior to and immediately after the Cretaceous-Paleogene boundary (66 Ma). This research involves measurements of carbon, oxygen and strontium isotopes in well-preserved shells of fossil molluscs, authigenic carbonate deposits and sediment formations.


Selected Publications

Krishnaswami, S. and J. K. Cochran. 2008. U-Th Series Nuclides in Aquatic Systems, Elsevier, New York, 458 pp.

Cochran, J.K. and P. Masqué. 2003. Short-lived U/Th series radionuclides in the ocean: Tracers for scavenging rates, export fluxes and particle dynamics. In: Uranium Series Geochemistry (B.P. Bourdon, G. Henderson, C.C. Lundstrom, S.P. Turner eds.), Reviews in Mineralogy and Geochemistry, vol. 52, Mineralogical Society of America, pp. 461-492.

Cochran, J. K., J. C. Miquel, R. Armstrong, S. Fowler, P. Masqué, B. Gasser, D. Hirschberg, J. Szlosek, A. M. Rodriguez y Baena, E. Verdeny, and G. Stewart (2009) Time-series measurements of 234Th in water column and sediment trap samples from the northwestern Mediterranean Sea. Deep-Sea Research II, doi:10.1016/j.dsr2.2008.12.034.

Cochran, J. K., N. H. Landman, N. L. Larson, K. C. Meehan, M. Garb, and J. Brezina (2015) Geochemical evidence (C and Sr isotopes) for methane seeps as ammonite habitats in the Late Cretaceous (Campanian) Western Interior Seaway. Swiss J Palaeontol. doi: 10.1007/s13358-015-0087-9.

Landman, N. H., J. K. Cochran, M. Slovacek, N. L. Larson, M. P. Garb, J. Brezina, and J. D. Witts (2018) Isotope sclerochronology of ammonites (Baculites compressus) from methane seep and non-seep sites in the Late Cretaceous Western Interior Seaway, USA: Implications for ammonite habitat and mode of life. American Journal of Science 318: 603-639

Tamborski, J. J., J. K. Cochran, and H.J. Bokuniewicz (2017) Submarine groundwater discharge driven nitrogen fluxes to Long Island Sound, NY: Terrestrial vs. marine sources. Geochimica et Cosmochimica Acta 218: 40–57.


Related News Articles

SoMAS Research featured as EOS Research Spotlight

The recent publication by SoMAS alum Shaily Rahman (PhD, 2016) and her advisors, Robert Aller and J. Kirk Cochran: "The Missing Silica Sink: Revisiting the Marine Sedimentary Si Cycle Using Cosmogenic 32Si" published in Global Biogeochemical Cycles 31, 1559 - 1578, is...

Retrospective Banquet 2017

Interim Dean Larry Swanson thanks everyone who joined us at our Retrospective Event: This wonderful event brought us all together to reminisce, reflect, and look hopefully to the future." Many thanks to our colleagues who helped put the evening together....

SoMAS 2016 Retrospective Banquet

Many thanks for those that joined us on December 14, 2016 for our Holiday Retrospective with great food and people. The highlight was when Santa arrived and the little ones all got a ride with him. A special thank you to those who helped organize the event including...

SoMAS Graduate Student Helps Develop Tool to Constrain Silicon Cycle

Our understanding of the global silicon (Si) cycle has changed progressively over the past several decades. In the late 1970’s, the silica (SiO2) produced by weathering on the continents and delivered in dissolved form from the world’s rivers to the ocean was thought...

Wen Cong, URECA Researcher of the Month – February 2016

From Wen Cong, URECA Researcher of the Month, February 2016 Marine Sciences major, Class of 2016 Research Mentor: Dr.Qingzhi Zhu, School of Marine & Atmospheric Sciences   “I am very lucky to have Dr. Zhu as my mentor,” reflects Wen Cong, a Marine Sciences major. “He...

Bermuda Rise (BaRFlux)

Principal Investigators: David Black, Cindy Lee, Rob Armstrong and Kirk Cochran Funded by NSF Ocean Sciences Division Students Supported: TBA Project Description:The goal of this work is to achieve a better mechanistic understanding of the ocean’s role in the global...

LIGRI Highlights of 2009

Research Activity Seepage and Nitrogen Inputs to Manhasset, Huntington and Great South Bays in collaboration with the USGS (Woods Hole) (Ruth Coffey, Ph.D. student) Groundwater links between land use and surface waters (R. Coffey, Ph.D. student) Groundwater coastline...

Dr. Qingzhi Zhu Joins SoMAS Faculty as Assistant Professor

This semester, SoMAS welcomed Dr. Qingzhi Zhu as Assistant Professor. Dr. Zhu has been part of the SoMAS community, as a research scientist and adjunct faculty member working with Dr. Robert Aller, since 2002. Dr. Zhu, who received his doctorate in Chemistry in 1997...

Continental Area Shelf Exchange Study (CASES)

Principle Investigators: Kirk Cochran at MSRC and Louis Fortier at Univ. Laval, Canada (CASES leader) Funded by NSERC – Natural Sciences and Engineering Research Council of Canada. Student Supported: David Amiel, M.S., Ph.D. Project Description: The overarching...

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