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Cycling of Nd isotope and rare earth elements (REEs) in the Amundsen Sea near the Antarctic ice shelves: US GEOTRACES GP17-ANT cruise


This project is part of US GEOTRACES programme intended to study trace elements and their isotopes in the global ocean. This specific project will study Nd isotope and rare earth element (REE) cycling in the Amundsen Sea near the Antarctic ice-shelf, with a particular focus on understanding the influence of melting ice sheet on local to global biogeochemical cycle and ocean circulation. A unique suite of samples (seawater, particles, sediments, etc.), collected from one of the remotest areas of the global ocean onboard US GEOTRACES GP17-ANT cruise, will be available for this project. More information about GP17-ANT cruise can be found here. The student on this project will receive extensive training in chemical oceanography and isotope geochemistry. The student will also get exposed to the large collaborative network of the international GEOTRACES programme


  • Knowledge on chemical oceanography, paleoceanography, or isotope geochemistry is essential

  • Experiences on working in chemical clean labs and mass spectrometery are highly desirable


Investigating modern and ancient K cycle and its implications for the global carbon cycle


Potassium is a major element in seawater and other surface environments, but, surprisingly, its geochemical cycle is rather poorly constrained relative to many other major elements. An improved understanding of the K cycle could have important implications for our climate, because the K cycle is tightly linked to silicate weathering and clay formation – two processes essential in maintaining the long-term stability of the global carbon cycle and ocean chemistry. This project, funded through a NSF CAREER award, will focus on development of an exciting new proxy – stable K isotopes – via a combination of controlled laboratory experiments, analyses of natural samples (e.g., hydrothermal fluids, sediments, soil and plants, etc), and theoretical calculations to improve our understanding of modern and ancient K cycle.


  • Knowledge on stable isotope geochemistry, chemical oceanography, or paleoceanography is essential

  • Experiences on working in chemical clean labs and mass spectrometery are highly desirable


Other possible topics


Suggestion of other research topics relevant to the overall reserach theme of my group is welcome. In particular, we are interested in research that applies Si isotopes to study modern and past Si cycle in the ocean. If you have experience on Si isotopes, please get in touch.


Prospective postdoc and visiting students/scholars are encouraged to contact me to discuss potential opportunities

My group is specialized in low-temperature isotope geochemistry. We develop new isotopic tools and apply them to studying key surface processes that control our climate and environment. My group offers the state-of-the-art facilities for geochemistry reserach, including a collision-cell MC-ICP-MS (Sapphire, Nu Instruments), a Triple-quad ICP-MS (iCAP TQ, Thermo), a femtosecond laser ablation system (Teledyne Photon Machines), a class-100 clean lab suite, and other general chemistry labs and equipment. Additional analytical and material characterization instruments are available within the department and on UMN campus.

My group values diversity and is strive to make our group a welcoming place for every motivated student to realize their full potential.

If you are interested, please send me your CV, a brief (max. 2-pages) statement that summarises your research experiences and interests via email: zhengxy [at] umn.edu.

Annual graduate application deadline: 15 Dec. Graudate students in department receive stable financial support typically through a combination of fellowship, TA, and RA. For international applicants who come from non-English speaking countries and do not have any degree from the USA before, please refer to University English Proficiency Requirements for admission and University Englsih Language Proficiency Requirements for TA. Details on graduate application can be found from: https://cse.umn.edu/esci/graduate-program-admissions