Jun  NISHIOKA

Kunio T.  TAKAHASHI

Takahiro  IIDA

Tomomi R.  TAKAMURA

Tsuneo  ODATE

National Institute of Polar Research Repository

JARE Data Reports, No. 338 (Marine Biology 51), July 2015      Biogeochemical properties of seawater in Lützow-Holm Bay in February 2011 during the 52nd Japanese Antarctic Research Expedition  Kunio T. TAKAHASHI1, 2*, Tomomi R. TAKAMURA1, Takahiro IIDA1, 2,  Jun NISHIOKA3 and Tsuneo ODATE1, 2  1 National Institute of Polar Research, Research Organization of Information and Systems, 10-3 Midori-cho, Tachikawa, Tokyo 190-8518. 2 Department of Polar Science, School of Multidisciplinary Sciences, SOKENDAI (The Graduate University for Advanced Studies), 10-3 Midori-cho, Tachikawa, Tokyo 190-8518. 3 Institute of Low Temperature Science, Hokkaido University, Kita-19, Nishi-8, Kita-ku, Sapporo, Hokkaido 060-0819. *Corresponding author. E-mail: takahashi.kunio@nipr.ac.jp   1. Introduction The powerful ice-breaking capacity of the Japanese icebreaker Shirase raises the possibility of marine observations in the first-ice and/or permanent-ice zone. As part of the marine biological monitoring program of the Japanese Antarctic Research Expedition (JARE), ship-based observations of the sea-ice region of Lützow-Holm Bay, off Syowa Station, East Antarctica, began during the 52nd Japanese Antarctic Research Expedition of 2010–2011 (JARE-52). The aim of this program is to investigate biological production and mechanisms in relation to sea ice. This report presents vertical profiles of the biogeochemical properties of seawater collected in Lützow-Holm Bay during February 2011.  2. Sampling Seawater samples for vertical profiles were collected at several monitoring stations in Lützow-Holm Bay (Stations A, B, C, D, and BP; Fig. 1) in February 2011. At the time of sampling, Stations A and B were in the multi-year fast-ice zone, Station C was in the first-year fast-ice zone, —　1　—K.T. Takahashi et al.     Station D was in the pack-ice zone, and Station BP was in the open-ocean zone. Details of sampling are given in Takahashi et al. (2012). Seawater was sampled to a depth of 400 m or to the bottom depth (whichever was less) during the down cast in standard 4 L Niskin bottles (Sea-Bird Electronics, Inc., Bellevue, WA, USA). Sampling was conducted at depths of 20, 50, 75, 100, 200, and 400 m at Stations D and BP; at 20 and 50 m at Station A; at 10, 30, 50, 75, 100, and 125 m at Station B; and at 20, 50, 75, 100, 200, and 230 m at Station C. Surface seawater was collected from the deck in a 5 L polyethylene bucket. Seawater was subsampled into 10 mL polyethylene screw-cap vials and 250 mL high-density polyethylene screw-cap light-blocking bottles to analyze the concentrations of inorganic nutrients and chlorophyll a, respectively. After subsampling, seawater samples for nutrient analysis were immediately stored in an ultra-low-temperature freezer (−85°C) until analysis on land. Phytoplankton chlorophyll a was extracted with N,N-dimethylformamide (Suzuki and Ishimaru, 1990) from a glass microfiber filter (Grade GF/F; Whatman, St. Louis, MO, USA) just after filtration; the samples were stored in a freezer (−18°C) until analysis on board.  3. Analysis Vertical temperature and salinity profiles were measured to a depth of 500 m or to the bottom depth with a conductivity–temperature–depth (CTD) memory probe (SBE 19plus; Sea-Bird Electronics, Inc.) attached to a water sampler (SBE 55 ECO; Sea-Bird Electronics, Inc.). The data were downloaded from the CTD to a laptop computer immediately after each cast. The CTD sensor was calibrated by the manufacturer prior to the cruise. Note that the salinity data reported here were not corrected by bottle salinity measured by salinometer. Concentrations of chlorophyll a were determined fluorometrically (Parsons et al., 1984) using an on-board fluorometer (10AU; Turner Designs, Sunnyvale, CA, USA). The fluorometer was calibrated against a chlorophyll a standard (Wako Pure Chemical Industries, Ltd., Osaka, Japan) at a laboratory on land prior to the cruise, using a spectrophotometer and the specific absorption coefficient of chlorophyll a (Porra et al., 1989). —　2　—JARE Data Reports, No. 338 (Marine Biology 51), July 2015     The samples for the nutrient concentration analyses were frozen and transported to a laboratory at Hokkaido University, Hokkaido, Japan. The frozen samples were thawed to room temperature starting the day before the analyses. Concentrations of the nutrients NO3 + NO2, PO4, SiO2, and NO2 were determined using a continuous-flow autoanalyzer (QuAAtro 2-HR; BL-TEC K.K., Osaka, Japan), according to the Joint Global Ocean Flux Study (JGOFS) spectrophotometric method (IOC/UNESCO, 1994). The nutrient concentrations were calibrated against KANSO reference materials (BT and BG; KANSO Technos Co., Ltd., Osaka, Japan).  4. Results Monitoring station information is listed in Table 1. Vertical profiles of temperature and salinity at each monitoring station are shown in Fig. 2; water analysis data, along with CTD data at defined depths, are listed in Table 2.  5. Data archive The data presented in this report are archived and available from the online Science Database of the National Institute of Polar Research (http://scidbase.nipr.ac.jp/?ml_lang=en). Permission to use these data for publication or presentation should be obtained in writing. Inquiries about the details of the data record should be addressed to: Kunio T. Takahashi National Institute of Polar Research Research Organization of Information and Systems 10-3 Midori-cho, Tachikawa, Tokyo 190-8518, Japan Tel: +81-42-512-0742 E-mail: takahashi.kunio@nipr.ac.jp  Acknowledgments We express our heartfelt appreciation to all members of JARE-52 for their support. We also thank the officers and crew of the icebreaker Shirase. —　3　—K.T. Takahashi et al.      References IOC/UNESCO (1994): Protocols for the Joint Global Ocean Flux Study (JGOFS) Core Measurements. Paris, UNESCO, 170 p. (IOC Manual and Guide, 29). http://hdl.handle.net/1834/2795. Parsons, T.R., Maita, Y. and Lalli, C.M. (1984): A manual of chemical and biological methods for seawater analysis. Oxford, Pergamon Press, 173 p. (Pergamon International Library of Science, Technology, Engineering and Social Studies). Porra, R.J., Thompson, W.A. and Kriedemann, P.E. (1989): Determination of accurate extinction coefficients and simultaneous equations for assaying chlorophylls a and b extracted with four different solvents: verification of the concentration of chlorophyll standards by atomic absorption spectroscopy. BBA-Bioenergetics, 975, 384–394. Suzuki, R. and Ishimaru, T. (1990): An improved method for the determination of phytoplankton chlorophyll using N,N-dimethylformamide. J. Oceanogr. Soc. Jpn., 46, 190–194. Takahashi, K.T., Iida, T., Hashida, G. and Odate, T. (2012): Field test of “ice-fence” for oceanographic observation in the sea-ice zone. Nankyoku Shiryô (Antarctic Record), 56, 447–455 (in Japanese with English abstract). —　4　— Fig. 1.  Locations of sampling stations occupied during the JARE-52 cruise. Solid squares indicate hydrocast stations. SIC% indicates the sea-ice concentration on 23 February 2011. The SIC data were obtained from daily AMSR2 sea-ice maps (http://www.iup.uni-bremen.de:8084/amsr2/). —　5　— Fig. 2.  Vertical profiles of temperature and salinity at the monitoring stations. —　6　—Table 1.  Monitoring station information   Station Date Time Latitude Longitude Bottom depth Air temperature Sea surface temperature Wind speed Atmospheric pressure (UTC) (UTC) (°S) (°E) (m) (°C) (°C) (m/s) (hPa) A 2011/2/9 13:12 69-03.03 39-20.55 77 –2.5 –0.8 0.7 990.2 B 2011/2/12 13:03 68-59.04 39-11.02 138 –7.0 –1.9 1.7 991.4 C 2011/2/18 05:07 68-31.31 38-42.12 233 –0.6 –1.8 1.3 996.2 D 2011/2/23 17:17 67-41.10 38-22.15 3806 –4.3 –1.6 7.6 966.1 BP 2011/2/24 04:45 66-49.43 37-50.61 4494 0.7 –0.5 6.1 970.6 —　7　—Table 2.  CTD and water analysis data at the monitoring stations  Stn Depth CTD data  Water analysis data Temperature Salinity  Nitrate  Nitrite Phosphate Silicate Chl a (dbar) (°C)   (μmol/L) (μmol/L) (μmol/L) (μmol/L) (μg/L) A 0 (Bucket) - -  18.1  0.0  1.3  39.0  2.47   20  –1.7936  33.9786   34.1  0.0  2.4  84.1  0.21   50  –1.6674  34.1000    30.8  0.0  2.2  72.9  0.08  B 0 (Bucket) - -  35.5  0.0  2.5  83.6  0.03   10  –1.8613  ND  35.3  0.0  2.6  84.5  0.02   30  –1.7742  ND  30.5  0.0  2.2  70.0  0.01   49  –1.7065  ND  31.6  0.0  2.3  73.5  0.01   74  –1.6591  ND  29.7  0.0  2.1  68.0  0.00   99  –1.6467  ND   34.1  0.0  2.5  79.5  0.00   123  –1.6377  ND   35.0  0.0  2.6  81.9  0.01  C 0 (Bucket) - -  30.1  0.1  2.1  64.8  0.36   20  –1.8205  33.9314   29.4  0.1  2.1  64.3  0.08   50  –1.7997  34.0441   34.6  0.0  2.6  78.0  0.07   74  –1.7851  34.0931   30.3  0.1  2.2  67.2  0.05   99  –1.7917  34.1288   33.8  0.1  2.5  78.0  0.04   199  –1.8374  34.2555   29.7  0.0  2.1  63.6  0.03   229  –1.7678  34.2838    29.8  0.0  2.1  64.7  - D 0 (Bucket) - -  29.7  0.2  2.1  69.9  0.25   20  –1.5548  33.7460   ND ND ND ND ND  50  –1.2956  33.8348   30.0  0.2  2.2  72.0  0.27   75  –1.7225  34.1731   30.7  0.1  2.2  72.1  0.21   100  –1.7035  34.2795   32.3  0.0  2.3  74.7  0.11   200  0.3838  34.5931   33.5  0.0  2.4  89.1  0.02   400  0.8606  34.6846    31.7  0.0  2.3  90.2  - BP 0 (Bucket) - -  28.6  0.1  2.0  67.9  0.77   20  –0.5162  34.0737   27.8  0.1  2.0  65.5  0.77   49  –0.2568  34.2096   31.1  0.1  2.3  76.7  1.01   75  1.1796  34.6372   34.7  0.1  2.5  90.3  0.56   98  1.2977  34.6585   35.9  0.0  2.6  94.7  0.18   199  1.4514  34.6989   34.7  0.0  2.5  95.2  0.01   396  1.3078  34.7222    34.2  0.0  2.5  97.0  - ND: no data. —　8　—

Biogeochemical properties of seawater in Lützow-Holm Bay in February 2011 during the 52nd Japanese Antarctic Research Expedition

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Biogeochemical properties of seawater in Lützow-Holm Bay in February 2011 during the 52nd Japanese Antarctic Research Expedition

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