섹션 개요

    • Seawater collected on board is brought back to the laboratory for analysis. In this study, quantification will be performed using a quantification method using a Turner fluorometer (Model 10-AU, Turner designs) (Welschmeyer, 1994). Dimethylformamide (DMF), an organic solvent, is used to extract pigment from phytoplankton (Suzuki and Ishimaru, 1990).

      Principle of chlorophyll fluorescence (movie)

    • what to prepare

      　Seawater sampled by ship, graduated cylinder, filter, suction pump, vacuum gauge, glass fiber filter (GF/F, ca. 0.7 µm, diameter 25 mm), tweezers, Sarstedt tube, glass tube (10 ml), Label stickers, DMF, Turner fluorometer, lab gloves


    • Filtration procedure

      1. Using tweezers, set the filter (glass fiber) in the strainer.
      2. Pour all the seawater in the water sampling bottle into each filter, and filter the seawater under reduced pressure (0.013 MPa or less).
      3. After filtration, immediately pour filtered seawater over the rim of the filter to filter out any particles remaining on the walls.
      4. After filtering, fold the filter with tweezers and lightly pinch it with filter paper to remove moisture.
      5. Place the filter in a Sarstedt tube containing 6 ml of DMF and mix gently (Note: DMF is harmful, so be sure to wear gloves to avoid contact with the skin. If it gets on your hands, wash it off immediately).

      Measurement procedure

      1. Turn on the Turner fluorometer (the spectrometer must be turned on 30 minutes to 1 hour before sample measurement in order to stabilize the lamp light source. It is a good idea to turn on the power before the above filtration procedure).
      2. Measure the high and low fluorescence values ​​of the secondary solid standard with a Turner fluorometer to check the condition of the equipment (this is done only for the first group). If there is no problem, proceed to the next step.
      3. Transfer the solution in the Sarstedt tube to a glass tube.
      4. As a blank, DMF alone is placed in a glass tube, and the glass tube is placed in a Turner fluorometer to read the fluorescence value (BLANK) (also for the first group only).
      5. Place the glass tube in the Turner fluorometer and read the fluorescence value at that time (F).

    • Method of calculation

      ◎chlorophyll a concentration (mg/m3)

      Chlorophyll a (mg/m3) = 0.164 × (F – BLANK) × v ÷ V                                                   (1)

      　　0.164: Slope between known chlorophyll a concentration and current fluorescence value(It is obtained by making several dilution series. Note that this value is slightly different for each device. Here, the calibration value performed in March 2020 is used.)

      　　v: Amount of organic solvent used for chlorophyll-a extraction (6 ml)
      　　V:       amount of filtered water (138.5 ml)

      Figure 1