Upward transport of bottom-ice dimethyl sulfide during advanced melting of arctic first-year sea ice

Gourdal, Margaux, Crabeck, Odile, Lizotte, Martine, Galindo, Virginie, Gosselin, Michel, Babin, Marcel, Scarratt, Michael and Levasseur, Maurice (2019) Upward transport of bottom-ice dimethyl sulfide during advanced melting of arctic first-year sea ice. Elementa, 7 (1). ISSN 2325-1026

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Abstract

This paper presents the first empirical estimates of dimethyl sulfide (DMS) gas fluxes across permeable sea ice in the Arctic. DMS is known to act as a major potential source of aerosols that strongly influence the Earth’s radiative balance in remote marine regions during the ice-free season. Results from a sampling campaign, undertaken in 2015 between June 2 and June 28 in the ice-covered Western Baffin Bay, revealed the presence of high algal biomass in the bottom 0.1-m section of sea ice (21 to 380 µg Chl a L–1) combined with the presence of high DMS concentrations (212–840 nmol L–1). While ice algae acted as local sources of DMS in bottom sea ice, thermohaline changes within the brine network, from gravity drainage to vertical stabilization, exerted strong control on the distribution of DMS within the interior of the ice. We estimated both the mean DMS molecular diffusion coefficient in brine (5.2 × 10–5 cm2 s–1 ± 51% relative S.D., n = 10) and the mean bulk transport coefficient within sea ice (33 × 10–5 cm2 s–1 ± 41% relative S.D., n = 10). The estimated DMS fluxes ± S.D. from the bottom ice to the atmosphere ranged between 0.47 ± 0.08 µmol m–2 d–1 (n = 5, diffusion) and 0.40 ± 0.15 µmol m–2 d–1 (n = 5, bulk transport) during the vertically stable phase. These fluxes fall within the lower range of direct summer sea-to-air DMS fluxes reported in the Arctic. Our results indicate that upward transport of DMS, from the algal-rich bottom of first-year sea ice through the permeable sea ice, may represent an important pathway for this biogenic gas toward the atmosphere in ice-covered oceans in spring and summer.

Item Type: Article
Uncontrolled Keywords: arctic,biogenic gas fluxes,dms,gas exchanges,sea ice,oceanography,environmental engineering,ecology,geotechnical engineering and engineering geology,geology,atmospheric science ,/dk/atira/pure/subjectarea/asjc/1900/1910
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Depositing User: LivePure Connector
Date Deposited: 12 Sep 2019 14:34
Last Modified: 06 Jul 2020 23:52
URI: https://ueaeprints.uea.ac.uk/id/eprint/72143
DOI: 10.1525/elementa.370

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