DMS flux over the Antarctic sea ice zone

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Publication details

Trevena, A & Jones, GB 2012, 'DMS flux over the Antarctic sea ice zone', Marine Chemistry, vol. 134-135, pp. 47-58.

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This study presents concentrations of dimethylsulphide (DMS) and its precursor compound dimethylsulphoniopropionate (DMSP), and chlorophyll a in a variety of sea ice and seawater habitats from pack and fast ice in the Antarctic Sea Ice Zone (ASIZ) of the Prydz Bay-Davis-Casey region of eastern Antarctica during spring and summer. These results were used to calculate the DMS flux from ice-free ocean water and melting sea ice in this region. Estimated seawater DMS concentrations derived from sea ice DMSPt released during ice melting showed that in October, sea ice derived DMS of the order of 20-50 nM is associated with DMSPt released from melting sea ice of 0.4 m thickness. In November and December, melting of large areas of ice less than 0.6 m thick could release larger amounts of DMS around 50-80 nM and 150-270 nM, respectively. In addition, DMSPt released from 1.0-1.2 m thick ice in December could result in "hot spot" concentrations of DMS of around 100 nM. DMS fluxes measured mainly in the Prydz Bay-Davis region in November and mid to late December were highest in pack ice > fast ice > ice edge (pack ice = 54 μmol m-2 d-1; range 1-325); fast ice = 28 μmol m-2 d-1; range 0-168); ice edge = 12 and 23 μmol m-2 d-1; range 1.2-26). In ice-free seawater in the Davis area from January to February, although dissolved DMS concentrations were low, DMS fluxes were high due to high wind speeds (DMS = 3 nM; DMS flux = 27 μmol m-2 d-1umol; range 1-101). DMS concentrations and flux from a fast ice tide crack (DMS = 12 nM; DMS flux 6-81 μmol m-2 d-1), and from the Davis region 2 days following fast ice breakout (DMS 12 nM; DMS flux 45-84 μmol m-2 d-1) were also a significant source of DMS to the atmosphere of this region. In contrast DMS and DMS flux from a fast ice melt-pool was low (DMS = 1 nM; DMS flux 0.5-7 μmol m-2 d-1). These measurements support the suggestion that during sea ice melting during late spring to early summer (November - December), the ASIZ is an area of high DMS (P) production, leading to very high fluxes of DMS to the atmosphere of this region. What effect this huge pulse of atmospheric DMS has on the radiative climate of this region is unknown.