• Login
    About WHOAS
    View Item 
    •   WHOAS Home
    • Woods Hole Oceanographic Institution
    • Academic Programs
    • WHOI Theses
    • View Item
    •   WHOAS Home
    • Woods Hole Oceanographic Institution
    • Academic Programs
    • WHOI Theses
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Browse

    All of WHOASCommunities & CollectionsBy Issue DateAuthorsTitlesKeywordsThis CollectionBy Issue DateAuthorsTitlesKeywords

    My Account

    LoginRegister

    Statistics

    View Usage Statistics

    Seasonal and interannual variability in the hydrology and geochemistry of an outlet glacier of the Greenland Ice Sheet

    Thumbnail
    View/Open
    Linhoff_thesis.pdf (14.28Mb)
    Date
    2016-02
    Author
    Linhoff, Benjamin S.  Concept link
    Metadata
    Show full item record
    Citable URI
    https://hdl.handle.net/1912/7591
    DOI
    10.1575/1912/7591
    Abstract
    In the spring and summer within the ablation zone of the Greenland Ice Sheet (GrIS), meltwater drains to the ice sheet bed through an evolving network of efficient channelized and inefficient distributed drainage systems. Distributed system drainage is a key component in stabilizing GrIS velocity on interannual time scales and controlling geochemical fluxes. During the spring and summer of 2011 and 2012, I conducted fieldwork at a large outlet glacier in southwest Greenland underlain by metamorphic silicate rocks. Data collected from a continuous 222Rn monitor in the proglacial river were used as a component of a mass balance model. I demonstrated that Jdis, the 222Rn fraction derived from the distributed system, was >90% of the 222Rn flux on average, and therefore, 222Rn can be used as a passive flow tracer of distributed system drainage. Supraglacial meltwater runoff estimated using two independent models was compared with ice velocity measurements across the glacier’s catchment. Major spikes of Jdis occurred after rapid supraglacial meltwater runoff inputs and during the expansion of the subglacial channelized system. While increases in meltwater runoff induced ice acceleration, they also resulted in the formation of efficient subglacial channels and increased drainage from the distributed system, mechanisms known to cause slower late summer to winter velocities. Sr, U, and Ra isotopes and major and trace element chemistry were used to investigate the impact of glacial hydrology on subglacial weathering. Analysis of partial and total digestions of the riverine suspended load (SSL) found that trace carbonates within the silicate watershed largely controlled the 87Sr/86Sr ratio in the dissolved load. Experiments and sampling transects downstream from the GrIS demonstrated that δ234U in the dissolved phase decreased with increasing interaction with the SSL. The (228Ra/226Ra) value of the dissolved load was significantly higher than that of the SSL and therefore, was not the result of the source rock material but of extensive mineral surface weathering and the faster ingrowth rate of 228Ra (t1/2=5.75 y) relative to 226Ra (t1/2=1600 y). In summary, extensive, repeated cycles of rapid supraglacial meltwater runoff to subglacial drainage networks leads to increased distributed system drainage and mineral weathering.
    Description
    Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution February 2016
    Collections
    • Marine Chemistry and Geochemistry (MC&G)
    • WHOI Theses
    Suggested Citation
    Thesis: Linhoff, Benjamin S., "Seasonal and interannual variability in the hydrology and geochemistry of an outlet glacier of the Greenland Ice Sheet", 2016-02, DOI:10.1575/1912/7591, https://hdl.handle.net/1912/7591
     

    Related items

    Showing items related by title, author, creator and subject.

    • Thumbnail

      Ocean circulation and dynamics on the west Antarctic Peninsula continental shelf 

      Moffat Varas, Carlos F. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2007-09)
      Observations of current velocity, temperature, salinity and pressure from a 2-year moored array deployment and four hydrographic cruises conducted by the United States Southern Ocean GLOBEC program on the western Antarctic ...
    • Thumbnail

      Testing the ancient marine redox record from oxygenic photosynthesis to photic zone euxina 

      French, Katherine L. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2015-02)
      Tracing the evolution of Earth’s redox history is one of the great challenges of geobiology and geochemistry. The accumulation of photosynthetically derived oxygen transformed the redox state of Earth’s surface environments, ...
    • Thumbnail

      Arctic Ocean circulation in an idealized numerical model 

      Sugimura, Peter Joseph (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2008-09)
      The mid-to-deep Arctic Ocean is generally characterized by a cyclonic circulation, contained along shelves and ridges. Here we analyze the general Arctic circulation using an idealized numerical model consisting of a ...
    All Items in WHOAS are protected by original copyright, with all rights reserved, unless otherwise indicated. WHOAS also supports the use of the Creative Commons licenses for original content.
    A service of the MBLWHOI Library | About WHOAS
    Contact Us | Send Feedback | Privacy Policy