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J. Kirk Cochran


Ph.D., 1979, Yale University

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


Research Interests

My research group and I are using natural radionuclides, as well as those produced by activities such as atomic weapons testing, 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 thorium isotopes 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, Equatorial Pacific and Southern Oceans, as well as the Mediterranean Sea The thorium isotopes 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. My group also has used natural radionuclides to characterize carbon export and transport in the Arctic in the Northeast Water and North Water Polynyas (seasonally ice free areas) and on the Mackenzie River shelf as part of the ongoing Canadian Arctic Shelf Exchange Study (CASES). We have also used natural and anthropogenic radionuclides to study the transport of sediments and associated contaminants by sea ice in the Arctic.

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) as well as the lagoon of Venice (Italy).

Selected Publications

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

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., D. J. Hirschberg and H. Feng. 2006. Reconstructing sediment chronologies in the Hudson River Estuary. In: The Hudson River Estuary (J. S. Levinton, J. R. Waldman eds.) Cambridge University Press, pp. 65-78.

Savoye, N., C. Benitez-Nelson, A. B. Burd, J. K. Cochran, M. Charette, K. O. Buesseler, G. A. Jackson, M. Roy-Barman, S. Schmidt and M. Elskens. 2006. 234Th sorption and export models in the water column: A review. Mar. Chem. 100, 224-249.

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.

Amiel, D., J.K. Cochran and D.J. Hirschberg. 2002. 234Th/238U disequilibrium as an indicator of the seasonal export flux of particulate organic carbon in the North Water. Deep-Sea Res. II, 49, 5191-5209.


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...

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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