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INTERACTIONS ENTRE COMPOSITION CHIMIQUE ET POPULATIONS MICROBIENNES DE LA NEIGE: QUELLES SONT LES CONSEQUENCES SUR LE CYCLE DU MERCURE EN ARCTIQUE ?

Abstract : The main objective of this thesis is to characterize the interactions between seasonal snow chemistry and microbial community structure in an arctic snowpack. In order to do so, the biotic and abiotic compartments of the snowpack must be first characterized. From snow and meltwater samples obtained during a two-month field study held in Ny-Ålesund (Svalbard, Norway, 78°56'N, 11°52'E) in 2007, we showed that the sequence diversity in arctic snow and meltwater libraries is elevated. We also examined the fate of Hg in an arctic snowpack, from its deposition during atmospheric mercury depletion events up until its transfer during snow melt and reported an increase in methylmercury concentrations in the snowpack during late spring. The results from this campaign highlighted the need to improve our knowledge on mercury speciation and led to the development of a mer-lux biosensor to measure the bioavailable fraction of mercury. We deployed the biosensor during a second two-month field campaign in Ny-Ålesund in spring 2008 and the results obtained led to a novel model for mercury methylation in oxic environments. In parallel, we followed changes in microbial community structure in snow and meltwater samples using a 16S microarray. We modeled the interactions between snow chemistry and community structure and found a significant co-structure. We also explored functional community changes due to mercury contamination of snowpacks. Based on our results, methylmercury affects community structure and function at concentrations much lower than previously reported. Our results provide a basis for further studies on the interaction between chemistry and microbial community structure.
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https://tel.archives-ouvertes.fr/tel-00452028
Contributor : Catherine Larose <>
Submitted on : Monday, February 1, 2010 - 1:06:08 PM
Last modification on : Thursday, November 19, 2020 - 3:54:26 PM
Long-term archiving on: : Friday, June 18, 2010 - 5:58:43 PM

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  • HAL Id : tel-00452028, version 1

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Catherine Larose. INTERACTIONS ENTRE COMPOSITION CHIMIQUE ET POPULATIONS MICROBIENNES DE LA NEIGE: QUELLES SONT LES CONSEQUENCES SUR LE CYCLE DU MERCURE EN ARCTIQUE ?. Planète et Univers [physics]. Université Joseph-Fourier - Grenoble I, 2010. Français. ⟨tel-00452028⟩

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