Arctic Field Projects

Project Title: Weathering of western Greenland: Influences on oceanic fluxes of radiogenic isotopes (Award# 1203773)

PI: Martin, Jonathan Bowman (
Phone: (352) 392.6219 
Institute/Department: U of Florida, Department of Geological Sciences 
IPY Project?
Funding Agency: US\Federal\NSF\GEO\OPP\ARC\ANS
Program Manager: Dr. Henrietta Edmonds ( )
Discipline(s): | Geological Sciences | Oceanography |

Project Web Site(s):

Science Summary:
This project addresses the hypothesis that as the Greenland Ice Sheet (GrIS) retreats, increased exposure and weathering will alter fluxes of radiogenic isotopes to the oceans. Radiogenic strontium (Sr) and lead (Pb) isotopes, and non­radiogenic neodymium (Nd) are preferentially leached during initial weathering of fresh bedrock and sediments in glacial terrains. With increased duration and intensity of weathering, isotopic compositions of runoff approach parent rock values. Therefore, magnitudes of offsets for Sr, Nd and Pb isotope values between water and bedrock provide information about the extent of chemical weathering. Specific hypotheses to be tested are (1) more radiogenic Sr and Pb and less radiogenic Nd discharge in water originating from the GrIS than from deglaciated watersheds without connections to the ice sheet, (2) values of isotope ratios depend on the exposure age of the deglaciated watersheds and the intensity of weathering in each environment, and (3) the total flux of radiogenic isotopes from continental glaciers depends on the relative aerial extents of glaciated and deglaciated watersheds. These hypotheses will be tested in western Greenland near Kangerlussuaq, where retreat of the GrIS since the Last Glacial Maximum has exposed an approximately 175 km wide strip of land. Water, sediment, and moraine material will be sampled from subglacial streams discharging from the outlet portals of the Russell and Leverett Glaciers, in the proglacial watershed of the Watson River, and in four deglaciated watersheds, not connected to the GrIS that drain moraines ranging in age from about 600 to 18,000 years. Additional samples will be located from a deglaciated region near Sisimiut that has a wetter climate and older moraines. Water samples will be measured for major and trace element concentrations to model potential mineral dissolution and contributions to isotope fluxes, and for Sr, Nd, and Pb isotope ratios to assess their fluxes from subglacial, proglacial, and deglaciated watersheds. This work will link terrestrial weathering products in a continental glacier setting to oceanic fluxes of radiogenic isotopes, thereby improving our ability to interpret marine records. The work is important because of its location near the formation regions of North Atlantic Deep Water and it should contribute to planning for a proposed ocean drilling expedition off Greenland. The work will impact human resources through incorporation of 4 students from undergraduate to Ph.D. level, all of whom will participate in field work and will work collaboratively to complete laboratory and data analyses. Results of the work will be used in several graduate and undergraduate courses and will be presented at national and international scientific meetings and through publications. Outreach will include lectures at local schools, as invited speakers at colleges and universities, and in the annual open house at the Florida Museum of Natural History.

Logistics Summary:
Researchers on this one-year project will sample de-glaciated, pro-glacial and sub-glacial watersheds in the vicinity of Kangerlussuaq and Sisimiut in Greenland to test the hypothesis that these environments produce distinct fluxes of radiogenic isotopes to the oceans. During the summer of 2013, a field team of four will spend approximately 8 weeks in Greenland collecting water, sediment and rock samples from sub-glacial streams discharging from the outlet portal of the Russell Glacier in the proglacial watershed of the Watson River between its source at outlet portal and its confluence with the Søndrestrøm Fjord. Researchers will travel via the ANG logistics chain Scotia><Kangerlussuaq, with a personnel change-out around the midpoint of the season. The team also will sample around five watersheds draining moraines that range in age from about 200 to 100,000 years old. They will spend about 20 days camping at remote locations for this work, spending the remaining nights in hotels in Sisimiut or at KISS. Remote sites will be accessed via helicopter and near- town sites via truck.

CPS will provide Air National Guard (ANG) coordination for researchers and gear, helicopter support, lodging and truck rental at KISS and in Sisimiut, intra-Greenland commercial air travel and freight, and inventory from NSF/CPS Kanger stocks including camping, communications and safety gear. All other items, including meals in Sisimiut and Kangerlussuaq and field food, will be paid by the researchers from the grant.
SeasonField SiteDate InDate Out#People
2013Greenland - Aasivissuit Tasiat07 / 12 / 2013 07 / 22 / 20134
2013Greenland - Kangerlussuaq06 / 03 / 2013 08 / 02 / 20137
2013Greenland - Narumaq Base Camp06 / 24 / 2013 07 / 04 / 20134
2013Greenland - Sisimiut06 / 13 / 2013 07 / 08 / 20134

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