Influence of short-term synoptic events and snow depth on DMS, DMSP, and DMSO dynamics in Antarctic spring sea ice - Université Pierre et Marie Curie Accéder directement au contenu
Article Dans Une Revue Elementa: Science of the Anthropocene Année : 2016

Influence of short-term synoptic events and snow depth on DMS, DMSP, and DMSO dynamics in Antarctic spring sea ice

Résumé

Temporal changes in the concentration profiles of dimethylsulfide (DMS), dimethylsulfoniopropio-nate (DMSP), and dimethylsulfoxide (DMSO) were measured in pack ice from the Bellingshausen Sea (Antarctica) during the winter-spring transition of 2007. Two sites with contrasting snow and ice thicknesses were sampled, with high concentrations of DMS, DMSP, and DMSO observed at both sites, especially in surface ice. These high concentrations were shown to correspond to the development of a surface ice microalgal community dominated by strong DMSP producers (flagellates and dinoflagel-lates) following flooding of the ice cover. Several short-term synoptic events were observed and shown to influence strongly the dynamics of sea ice DMS, DMSP, and DMSO. In particular, a cold spell event was associated with drastic changes in the environmental conditions for the sea ice microbial communities and to a remarkable increase in the production of dimethylated sulfur compounds at both sites. A good correlation between all dimethylated sulfur compounds, sea ice temperature, and brine salinity suggested that the observed increase was triggered mainly by increased thermal and osmotic stresses on microalgal cells. Atmospheric forcing, by controlling sea ice temperature and hence the connectivity and instabil-ity of the brine network, was also shown to constrain the transfer of dimethylated sulfur compounds in the ice towards the ocean via brine drainage. Analysis of the two contrasting sampling sites shed light on the key role played by the snow cover in the sea ice DMS cycle. Thicker snow cover, by insulating the underlying sea ice, reduced the amplitude of environmental changes associated with the cold spell, leading to a weaker physiological response and DMS, DMSP, and DMSO production. Thicker snow also hampered the development of steep gradients in sea ice temperature and brine salinity, thereby decreasing the potential for the release of dimethylated sulfur compounds to the ocean via brine drainage.

Dates et versions

hal-01406227 , version 1 (30-11-2016)

Identifiants

Citer

Gauthier Carnat, Frédéric Brabant, Isabelle Dumont, M. Vancoppenolle, Stephen F. Ackley, et al.. Influence of short-term synoptic events and snow depth on DMS, DMSP, and DMSO dynamics in Antarctic spring sea ice. Elementa: Science of the Anthropocene, 2016, 4, pp.000135. ⟨10.12952/journal.elementa.000135⟩. ⟨hal-01406227⟩
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