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Biogeosciences An interactive open-access journal of the European Geosciences Union
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Volume 15, issue 10 | Copyright

Special issue: NETCARE (Network on Aerosols and Climate: Addressing Key Uncertainties...

Biogeosciences, 15, 3169-3188, 2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Research article 29 May 2018

Research article | 29 May 2018

Dimethyl sulfide dynamics in first-year sea ice melt ponds in the Canadian Arctic Archipelago

Margaux Gourdal1, Martine Lizotte1, Guillaume Massé1, Michel Gosselin2, Michel Poulin3, Michael Scarratt4, Joannie Charette2, and Maurice Levasseur1 Margaux Gourdal et al.
  • 1Département de biologie, Québec-Océan and Unité Mixte Internationale 3376 TAKUVIK, CNRS-Université Laval, 1045 Avenue de la Médecine, Ville de Québec, Québec G1V 0A6, Canada
  • 2Institut des Sciences de la Mer de Rimouski (ISMER), Université du Québec à Rimouski, 310 Allée des Ursulines, Rimouski, Québec G5L 3A1, Canada
  • 3Research and Collections, Canadian Museum of Nature, P.O. Box 3443, Station D, Ottawa, Ontario K1P 6P4, Canada
  • 4Maurice Lamontagne Institute, Fisheries and Oceans Canada, P.O. Box 1000, Mont-Joli, Québec G5H 3Z4, Canada

Abstract. Melt pond formation is a seasonal pan-Arctic process. During the thawing season, melt ponds may cover up to 90% of the Arctic first-year sea ice (FYI) and 15 to 25% of the multi-year sea ice (MYI). These pools of water lying at the surface of the sea ice cover are habitats for microorganisms and represent a potential source of the biogenic gas dimethyl sulfide (DMS) for the atmosphere. Here we report on the concentrations and dynamics of DMS in nine melt ponds sampled in July 2014 in the Canadian Arctic Archipelago.  DMS concentrations were under the detection limit ( < 0.01nmolL−1) in freshwater melt ponds and increased linearly with salinity (rs = 0.84, p ≤ 0.05) from  ∼ 3 up to  ∼ 6nmolL−1 (avg. 3.7±1.6nmolL−1) in brackish melt ponds. This relationship suggests that the intrusion of seawater in melt ponds is a key physical mechanism responsible for the presence of DMS. Experiments were conducted with water from three melt ponds incubated for 24h with and without the addition of two stable isotope-labelled precursors of DMS (dimethylsulfoniopropionate), (D6-DMSP) and dimethylsulfoxide (13C-DMSO). Results show that de novo biological production of DMS can take place within brackish melt ponds through bacterial DMSP uptake and cleavage. Our data suggest that FYI melt ponds could represent a reservoir of DMS available for potential flux to the atmosphere. The importance of this ice-related source of DMS for the Arctic atmosphere is expected to increase as a response to the thinning of sea ice and the areal and temporal expansion of melt ponds on Arctic FYI.

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Melt ponds (MP) forming over first year ice (FYI) represent a potential source of the climate-relevant gas dimethylsulfide (DMS) to the atmosphere. Nine MP were sampled in the Canadian Arctic Archipelago. DMS concentrations reaching up to 6 nmol L−1, twice the world's surface oceanic mean, were measured. Seawater intrusion appeared to seed MP with DMS-producing communities. DMS flux from Arctic MP is expected to increase in response to the expanding areal and temporal trends of MP on FYI.
Melt ponds (MP) forming over first year ice (FYI) represent a potential source of the...