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Hydrological and biogeochemical cycling along the Greenland ice sheet margin

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dc.contributor.author Bhatia, Maya P.
dc.coverage.spatial Greenland
dc.date.accessioned 2012-04-19T13:13:12Z
dc.date.available 2012-04-19T13:13:12Z
dc.date.issued 2012-02
dc.identifier.uri http://hdl.handle.net/1912/5135
dc.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 2012 en_US
dc.description.abstract Global warming has led to a significant increase in Greenland ice sheet (GrIS) melt and runoff since 1990, resulting in escalated export of fresh water and associated sediment to the surrounding North Atlantic and Arctic Oceans. Similar to alpine glacial systems, surface meltwater on ice sheet surface drains to the base (subglacial) where it joins a drainage system and can become chemically enriched from its origin as dilute snow- and ice-melt. In this thesis, I examine the interdependence of glacial hydrology and biogeochemical cycling in terms of export of carbon and iron from the Greenland ice sheet. I develop a new isotope mixing-model to quantify water source contributions to the bulk meltwater discharge draining a GrIS outlet glacier. Results illustrate (a) the new application of a naturally occurring radioisotope (radon-222) as a quantitative tracer for waters stored at the glacier bed, and (b) the seasonal evolution of the subglacial drainage network from a delayed-flow to a quick-flow system. Model results also provide the necessary hydrological context to interpret and quantify glacially-derived organic carbon and iron fluxes. I combine bulk- and molecular-level studies of subglacial organic carbon to show that GrIS discharge exports old (radiocarbon depleted), labile organic matter. Similar investigations of dissolved and particulate iron reveal that GrIS discharge may be a significant flux of labile iron to the North Atlantic Ocean during the summer meltseason. Both carbon and iron are subject to proglacial processing prior to export to the marine environment, and exhibit strong seasonal variability in correlation with the subglacial drainage evolution. Low, chemically concentrated fluxes characterize the spring discharge, whereas higher, chemically dilute fluxes typify the summer discharge. Collectively, this thesis provides some of the first descriptions and flux estimates of carbon and iron, key elements in ocean biogeochemical cycles, in GrIS meltwater runoff. en_US
dc.description.sponsorship This research was supported the WHOI Arctic Research Initiative (EBK, SBD, MAC), the National Science Foundation (EBK, SBD), NASA (SBD), a National Science and Engineering Research Council of Canada Postgraduate Doctoral Fellowship (MPB), an American Geophysical Union Horton Hydrology Award (MPB), the Ocean Ventures Fund (MPB), and the WHOI Climate Change Institute (MPB). en_US
dc.format.mimetype application/pdf
dc.language.iso en_US en_US
dc.publisher Massachusetts Institute of Technology and Woods Hole Oceanographic Institution en_US
dc.relation.ispartofseries WHOI Theses en_US
dc.subject Glaciology en_US
dc.subject Biogeochemical cycles en_US
dc.title Hydrological and biogeochemical cycling along the Greenland ice sheet margin en_US
dc.type Thesis en_US
dc.identifier.doi 10.1575/1912/5135


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