36
The Radiocarbon Method to Estimate Primary Production
with water, leaving 1-2-cm 3 air bubble under the stoppers. One of the three
bottles will serve as the dark control, and should be placed into a black bag
made of two or three layers of black cloth or tightly wrapped over with the
aluminum foil. Before use, the bags should be controlled for light penetration
by a photometer. Two other bottles represent parallel light bottles. Equal portions of 14C-carbonatt: working solution are then injected intu the bottles and
their contents instantly mixed. Optimal volumes of working solution for the
injection are 0.2-0.3 ml, which should be inserted with the aid of an automatic
pipet and should have a radioactivity roughly corresponding to the expected
primary production in accordance with the trophical status and kind of
water body under examination. In oligotrophic waters of the tropical ocean,
it should be between 8 and 12 x 10 6 cpm, in mesotrophic temperate marine
waters 2-3 x 10 6 cpm, in eutrophic marine coastal waters and in lagoons 0.3-0.5
x 10 6 cpm; in mesotrophic freshwaters, it should be 0.6-1 x 10 6 cpm, and in
eutrophic -0.1 to 0.2 x 10 6 cpm. This is the approximate range of radioactivity
which should be added per experimental sample bottle (R;). Correspondingly,
the radioactivity of the working 14C-carbonate solution (Rw, see Sect. 2.5.3)
should be three to five times more if the amount added into the bottles is
0.2-0.3ml.
The bottles with added isotope are closed with stoppers and mixed. The
stoppers are then covered with plastic film, fixed with rubber bands, which prevents their accidental opening during exposure and protects them from contamination, which might penetrate through the ground glass stoppers. The
bottles are now ready for exposure. The conditions of exposure will depend
upon the kind of values intended and on the conditions of field work. Here
we will consider only cases when the goal of the measurements is values of
primary production per day in the surface water layer (Cps> mgCm- 3 day-I).
When working in relatively small-sized lakes of 5-6km or less or in
lagoons, the most practical way of sampling and incubation is as follows.
Surface samples are collected in the morning into 1.5-1 polycarbonate bottles.
The bottles should be filled completely with water and kept in the shade
to preserve in them at quasi in situ temperature. At the end of the mission,
the samples thus collected are rapidly driven into the coastal field laboratory
and kept in the shade, where they are distributed into the experimental bottles
to estimate photosynthesis rates. The bottles are charged with the isotopic
working solution and placed into a special incubation stand made of the transparent Plexiglas plates with holes at the bottom. It looks like a shallow aquarium with 5 cm walls divided inside in lateral sections by 2-cm plastic walls to
fix the bottles between them. The stand should be mounted in the water body
on a frame at a depth of some 15cm under the surface. To one side of the
frame, a black box should be attached for exposure of the dark bottles (cf.
below, Fig. 2.20).
During oceanographic cruises, the stations are usually sampled throughout the 24 h. In this case, the samples for Cps estimations collected late in the
afternoon later than 4h before sunset and also at night should be kept until
The Radiocarbon Method to Estimate Primary Production
with water, leaving 1-2-cm 3 air bubble under the stoppers. One of the three
bottles will serve as the dark control, and should be placed into a black bag
made of two or three layers of black cloth or tightly wrapped over with the
aluminum foil. Before use, the bags should be controlled for light penetration
by a photometer. Two other bottles represent parallel light bottles. Equal portions of 14C-carbonatt: working solution are then injected intu the bottles and
their contents instantly mixed. Optimal volumes of working solution for the
injection are 0.2-0.3 ml, which should be inserted with the aid of an automatic
pipet and should have a radioactivity roughly corresponding to the expected
primary production in accordance with the trophical status and kind of
water body under examination. In oligotrophic waters of the tropical ocean,
it should be between 8 and 12 x 10 6 cpm, in mesotrophic temperate marine
waters 2-3 x 10 6 cpm, in eutrophic marine coastal waters and in lagoons 0.3-0.5
x 10 6 cpm; in mesotrophic freshwaters, it should be 0.6-1 x 10 6 cpm, and in
eutrophic -0.1 to 0.2 x 10 6 cpm. This is the approximate range of radioactivity
which should be added per experimental sample bottle (R;). Correspondingly,
the radioactivity of the working 14C-carbonate solution (Rw, see Sect. 2.5.3)
should be three to five times more if the amount added into the bottles is
0.2-0.3ml.
The bottles with added isotope are closed with stoppers and mixed. The
stoppers are then covered with plastic film, fixed with rubber bands, which prevents their accidental opening during exposure and protects them from contamination, which might penetrate through the ground glass stoppers. The
bottles are now ready for exposure. The conditions of exposure will depend
upon the kind of values intended and on the conditions of field work. Here
we will consider only cases when the goal of the measurements is values of
primary production per day in the surface water layer (Cps> mgCm- 3 day-I).
When working in relatively small-sized lakes of 5-6km or less or in
lagoons, the most practical way of sampling and incubation is as follows.
Surface samples are collected in the morning into 1.5-1 polycarbonate bottles.
The bottles should be filled completely with water and kept in the shade
to preserve in them at quasi in situ temperature. At the end of the mission,
the samples thus collected are rapidly driven into the coastal field laboratory
and kept in the shade, where they are distributed into the experimental bottles
to estimate photosynthesis rates. The bottles are charged with the isotopic
working solution and placed into a special incubation stand made of the transparent Plexiglas plates with holes at the bottom. It looks like a shallow aquarium with 5 cm walls divided inside in lateral sections by 2-cm plastic walls to
fix the bottles between them. The stand should be mounted in the water body
on a frame at a depth of some 15cm under the surface. To one side of the
frame, a black box should be attached for exposure of the dark bottles (cf.
below, Fig. 2.20).
During oceanographic cruises, the stations are usually sampled throughout the 24 h. In this case, the samples for Cps estimations collected late in the
afternoon later than 4h before sunset and also at night should be kept until