Towards an understanding of the physical and biological controls on the cycling of dimethylsulfide (DMS) in Arctic and Antarctic sea ice

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dc.contributor.supervisor Papakyriakou, Timothy (Environment and Geography) en_US
dc.contributor.author Carnat, Gauthier
dc.date.accessioned 2014-08-01T17:03:55Z
dc.date.available 2014-08-01T17:03:55Z
dc.date.issued 2013-10 en_US
dc.date.issued 2014-05-01 en_US
dc.identifier.citation Carnat, G., T. Papakyriakou, N.-X. Geilfus, F. Brabant, B. Delille, M. Vancoppenolle, G. Gilson, J. Zhou, and J.-L. Tison (2013), Investigations on physical and textural properties of Arctic first-year sea ice in the Amundsen Gulf, Canada, November 2007-June 2008 (IPY-CFL system study), J. Glaciol., 59, 217, doi:10.3189/2013JoG12J148 en_US
dc.identifier.citation Carnat, G., J. Zhou, T. Papakyriakou, B. Delille, T. Goossens, T. Haskell, V. Schoemann, F. Fripiat, J.-M. Rintala, and J.-L. Tison (2014), Physical and biological controls on DMS,P dynamics in ice-shelf influenced fast ice during a winter-spring and a spring-summer transitions, J. Geophys. Res. Oceans, 119, doi:10.1002/2013JC009381 en_US
dc.identifier.uri http://hdl.handle.net/1993/23732
dc.description.abstract Little is known about the factors driving the cycle of the climate-active gas dimethylsulfide (DMS) and of its precursor the metabolite dimethylsulfoniopropionate (DMSP) in sea ice. To date, studies have focused on biotic factors, linking high DMSP concentrations to the high biomass of sympagic communities, and to physiological adaptations to the low temperatures and high salinities of the brine habitat. This thesis presents an approach integrating biotic and abiotic factors, investigating the influence of ice growth processes and brine dynamics on the DMS cycle. First, brine dynamics from growth to melt are explored based on ice temperature and salinity profiles measured in the Arctic. A strong but brief desalination phase is identified in spring. Using calculated proxies of permeability (brine volume fraction) and of the intensity of brine convection (Rayleigh number), this phase is shown to correspond to full-depth gravity drainage initiated by restored connectivity of brines on warming. Full-depth gravity drainage is crucial for the vertical transfer of DMS-compounds at the ice-ocean interface. This physical background is then used to investigate the spatio-temporal variability of DMS in Arctic sea ice during a year-round survey in Amundsen Gulf. The influence of processes such as scavenging and brine convection on the DMS cycle is shown, and the first combined measurement of DMS, DMSP, and dimethylsulfoxide (DMSO), a compound acting as source/sink for DMS through photo-chemical and bacterial processes, is presented. DMSO is shown to dominate the dimethylated sulfur pool in surface ice when the snow cover is low. Based on correlations with irradiance, it is suggested that this DMSO originates from photo-chemical oxidation of DMS trapped in impermeable ice. Finally, the spatio-temporal variability of DMS in Antarctic sea ice is investigated during another year-round survey in McMurdo Sound. Platelet crystals growth under the influence of ice-shelf waters are shown to favor the incorporation of strong DMSP producers, to increase the environmental stress on cells, and to favor the accumulation of DMS,P by reducing permeability. The increase of permeability on warming is shown to trigger strong release of DMS in the ocean and a vertical redistribution of DMSP in the ice cover. en_US
dc.publisher International Glaciological Society en_US
dc.publisher John Wiley & Sons en_US
dc.rights info:eu-repo/semantics/openAccess
dc.subject Dimethylsulfide en_US
dc.subject Sea ice en_US
dc.subject Sulfur en_US
dc.subject Arctic en_US
dc.subject Antarctic en_US
dc.title Towards an understanding of the physical and biological controls on the cycling of dimethylsulfide (DMS) in Arctic and Antarctic sea ice en_US
dc.type info:eu-repo/semantics/doctoralThesis
dc.degree.discipline Environment and Geography en_US
dc.contributor.examiningcommittee Feiyue, Wang (Environment and Geography)Tenuta, Mario (Soil Science)Ackley, Stephen (Geological Sciences, University of Texas at San Antonio) en_US
dc.degree.level Doctor of Philosophy (Ph.D.) en_US
dc.description.note October 2014 en_US

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