Seasonal and interannual variability in the hydrology and geochemistry of an outlet glacier of the Greenland Ice Sheet
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 In the spring and summer within the ablation zone of the Greenland Ice Sheet (GrIS), meltwater drains to...
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Massachusetts Institute of Technology and Woods Hole Oceanographic Institution
2016
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ftwhoas:oai:darchive.mblwhoilibrary.org:1912/7591 2023-05-15T16:21:19+02:00 Seasonal and interannual variability in the hydrology and geochemistry of an outlet glacier of the Greenland Ice Sheet Linhoff, Benjamin S. 2016-02 application/pdf https://hdl.handle.net/1912/7591 en_US eng Massachusetts Institute of Technology and Woods Hole Oceanographic Institution WHOI Theses https://hdl.handle.net/1912/7591 doi:10.1575/1912/7591 doi:10.1575/1912/7591 Thesis 2016 ftwhoas https://doi.org/10.1575/1912/7591 2022-05-28T22:59:25Z 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 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 ... Thesis glacier Greenland Ice Sheet Woods Hole Scientific Community: WHOAS (Woods Hole Open Access Server) Greenland Woods Hole, MA |
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Open Polar |
collection |
Woods Hole Scientific Community: WHOAS (Woods Hole Open Access Server) |
op_collection_id |
ftwhoas |
language |
English |
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 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 ... |
format |
Thesis |
author |
Linhoff, Benjamin S. |
spellingShingle |
Linhoff, Benjamin S. Seasonal and interannual variability in the hydrology and geochemistry of an outlet glacier of the Greenland Ice Sheet |
author_facet |
Linhoff, Benjamin S. |
author_sort |
Linhoff, Benjamin S. |
title |
Seasonal and interannual variability in the hydrology and geochemistry of an outlet glacier of the Greenland Ice Sheet |
title_short |
Seasonal and interannual variability in the hydrology and geochemistry of an outlet glacier of the Greenland Ice Sheet |
title_full |
Seasonal and interannual variability in the hydrology and geochemistry of an outlet glacier of the Greenland Ice Sheet |
title_fullStr |
Seasonal and interannual variability in the hydrology and geochemistry of an outlet glacier of the Greenland Ice Sheet |
title_full_unstemmed |
Seasonal and interannual variability in the hydrology and geochemistry of an outlet glacier of the Greenland Ice Sheet |
title_sort |
seasonal and interannual variability in the hydrology and geochemistry of an outlet glacier of the greenland ice sheet |
publisher |
Massachusetts Institute of Technology and Woods Hole Oceanographic Institution |
publishDate |
2016 |
url |
https://hdl.handle.net/1912/7591 |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
glacier Greenland Ice Sheet |
genre_facet |
glacier Greenland Ice Sheet |
op_source |
doi:10.1575/1912/7591 |
op_relation |
WHOI Theses https://hdl.handle.net/1912/7591 doi:10.1575/1912/7591 |
op_doi |
https://doi.org/10.1575/1912/7591 |
op_publisher_place |
Woods Hole, MA |
_version_ |
1766009334139977728 |