Dimethylsulphide and dimethylsulphoniopropionate in Antarctic sea ice and their release during sea ice melting |
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| Institution: | 1. Département des Sciences de la Terre et de l''Environment, Université Libre de Bruxelles, Brussels 1050, Belgium;2. School of Environmental Science and Management, Southern Cross University, Lismore, New South Wales 2480, Australia;3. Department of Environment, North West Region, PO Box 836, Karratha 6714, Australia;1. Department of Oceanography, Pusan National University, 30, Jangjeon-dong, Geumjeong-gu, Busan 609-735, Republic of Korea;2. Korea Polar Research Institute, 26 Songdomirae-ro, Yeonsu-gu, Incheon 406-840, Republic of Korea;1. V.I.Il’ichev Pacific Oceanological Institute, Far Eastern Branch, Russian Academy of Sciences (POI FEB RAS), 43 Baltiyskaya Street, Vladivostok 690041, Russia;2. International Arctic Research Center, University of Alaska, 930 Koyukuk Dr., P.O. Box 757340, Fairbanks, AK 99775, USA;3. National Research Tomsk Polytechnic University, Tomsk, Russia;1. Graduate School of Environmental and Human Sciences, Meijo University, Nagoya 468-8502, Japan;2. Research Institute, Meijo University, Nagoya 468-8502, Japan;3. Department of Microbiology, Faculty of Science, Chulalongkorn University, Patumwan, Bangkok 10330, Thailand |
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| Abstract: | This study presents concentrations of dimethylsulphide (DMS) and its precursor compound dimethylsulphoniopropionate (DMSP) in a variety of sea ice and seawater habitats in the Antarctic Sea Ice Zone (ASIZ) during spring and summer. Sixty-two sea ice cores of pack and fast ice were collected from twenty-seven sites across an area of the eastern ASIZ (64°E to 110°E; and the Antarctic coastline north to 62°S). Concentrations of DMS in 81 sections of sea ice ranged from < 0.3 to 75 nM, with an average of 12 nM. DMSP in 60 whole sea ice cores ranged from 25 to 796 nM and showed a negative relationship with ice thickness (y = 125x? 0.8). Extremely high DMSP concentrations were found in 2 cores of rafted sea ice (2910 and 1110 nM). The relationship of DMSP with ice thickness (excluding rafted ice) suggests that the release of large amounts of DMSP during sea ice melting may occur in discrete areas defined by ice thickness distribution, and may produce ‘hot spots’ of elevated seawater DMS concentration of the order of 100 nM. During early summer across a 500 km transect through melting pack ice, elevated DMS concentrations (range 21–37 nM, mean 31 nM, n = 15) were found in surface seawater. This band of elevated DMS concentration appeared to have been associated with the release of sea ice DMS and DMSP rather than in situ production by an ice edge algal bloom, as chlorophyll a concentrations were relatively low (0.09–0.42 μg l? 1). During fast ice melting in the area of Davis station, Prydz Bay, sea ice DMSP was released mostly as extracellular DMSP, since intracellular DMSP was negligible in both hyposaline brine (5 ppt) and in a melt water lens (4–5 ppt), while extracellular DMSP concentrations were as high as 149 and 54 nM, respectively in these habitats. DMS in a melt water lens was relatively high at 11 nM. During the ice-free summer in the coastal Davis area, DMS concentrations in surface seawater were highest immediately following breakout of the fast ice cover in late December (range 5–14 nM), and then remained at relatively low concentrations through to late February (< 0.3–6 nM). These measurements support the view that the melting of Antarctic sea ice produces elevated seawater DMS due to release of sea ice DMS and DMSP. |
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