Technique of Measuring Phytoplankton Primary Production
29
attached to a syringe. Then the container is placed inside a small beaker or
short test tube 4-S cm high. The latter is transferred into the device for 14C02
distillation, placed inside a filtration flask of some O.S-l capacity, containing
SO-lOOml 0.02N KOH solution. The flask is then closed with a rubber stopper
with a funnel (Fig. 2.1). The end of this funnel is inserted right into the opened
batch container with tht: labded carbonate. The flask is then emptied down to
100-200mmHg, and drop by drop the 2% H 2S04 solution is added into the
batch until the liquid completely fills the container and more than half the
volume of the beaker in which it stands. The flask should be left for 1-2 days
for complete absorption by the alkaline of the 14C02 thus developed. After
this, the vacuum is released with the valve, and the stopper with the funnel is
carefully taken out. The alkaline solution with 14C02 absorbed is transferred
into a 2S0-ml BOD bottle and its radioactivity is roughly estimated by liquid
scintillation counting. For this, O.S ml is diluted in 100ml of O.S% Na2C03 solution +20 mg KOH. Then the glass fiber filter is placed at the bottom of the scintillation vial, and into it 0.1-0.S ml of this dilution +1 ml of methoxyethanol or
ethanol + scintillation cocktail are added. When the approximate radioactivity of the solution is thus established, it is diluted to the required radioactivity level of ca. 1-2 x 106 cpmm l-1 for work in eutrophic waters, ca. 6-10 x 10 6
cpm ml- 1 for work in mesotrophic waters, and ca. lS-2S x 10 6 cpm ml- I for work
in oceanic oligotrophic waters. Appropriately diluted solutions are then neutralized to pH 9.2-9.S with 0.1 N HCl. Into the stock thus prepared for work
in the sea, 4 g NaCl per 100ml is added. The working solution prepared with
NaCl will not float on being added to seawater samples, and will not be lost
on closing the bottles with glass stoppers. The following step is the filtration
of the working solution through a membrane filter of 0.1-0.2-).lm pore size.
'---..----+-,- -
vacuum
3
: : - - - - - - -
Fig. 2.1. Device for cleaning Na2C03 by
passage via the gas phase. 1 funnel with
5% H 2S04; 2 beaker with batch of concentrated Na214C03 (2-5mCi); 3 O.05N KOH
solution
29
attached to a syringe. Then the container is placed inside a small beaker or
short test tube 4-S cm high. The latter is transferred into the device for 14C02
distillation, placed inside a filtration flask of some O.S-l capacity, containing
SO-lOOml 0.02N KOH solution. The flask is then closed with a rubber stopper
with a funnel (Fig. 2.1). The end of this funnel is inserted right into the opened
batch container with tht: labded carbonate. The flask is then emptied down to
100-200mmHg, and drop by drop the 2% H 2S04 solution is added into the
batch until the liquid completely fills the container and more than half the
volume of the beaker in which it stands. The flask should be left for 1-2 days
for complete absorption by the alkaline of the 14C02 thus developed. After
this, the vacuum is released with the valve, and the stopper with the funnel is
carefully taken out. The alkaline solution with 14C02 absorbed is transferred
into a 2S0-ml BOD bottle and its radioactivity is roughly estimated by liquid
scintillation counting. For this, O.S ml is diluted in 100ml of O.S% Na2C03 solution +20 mg KOH. Then the glass fiber filter is placed at the bottom of the scintillation vial, and into it 0.1-0.S ml of this dilution +1 ml of methoxyethanol or
ethanol + scintillation cocktail are added. When the approximate radioactivity of the solution is thus established, it is diluted to the required radioactivity level of ca. 1-2 x 106 cpmm l-1 for work in eutrophic waters, ca. 6-10 x 10 6
cpm ml- 1 for work in mesotrophic waters, and ca. lS-2S x 10 6 cpm ml- I for work
in oceanic oligotrophic waters. Appropriately diluted solutions are then neutralized to pH 9.2-9.S with 0.1 N HCl. Into the stock thus prepared for work
in the sea, 4 g NaCl per 100ml is added. The working solution prepared with
NaCl will not float on being added to seawater samples, and will not be lost
on closing the bottles with glass stoppers. The following step is the filtration
of the working solution through a membrane filter of 0.1-0.2-).lm pore size.
'---..----+-,- -
vacuum
3
: : - - - - - - -
Fig. 2.1. Device for cleaning Na2C03 by
passage via the gas phase. 1 funnel with
5% H 2S04; 2 beaker with batch of concentrated Na214C03 (2-5mCi); 3 O.05N KOH
solution